Download Cong.heart_desiases.docx

Cong.heart_desiases.docx
Олена Костянтинівна Редько
2015
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Зміст
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Acyanotic Congenital Heart Disease
Heart and Main Vessels
Atrioventricular Septal Defects (Ostium Primum and Atrioventricular Canal or
Endocardial Cushion Defects)
Cyanotic Congenital Heart Disease
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Acyanotic Congenital Heart Disease
Heart and Main Vessels
Atrioventricular Septal Defects (Ostium Primum and Atrioventricular Canal or Endocardial Cushion
Defects)
Cyanotic Congenital Heart Disease
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Atrial Septal Defect, Atrioventricular Septal Defects (Ostium Primum and Atrioventricular Canal or
Endocardial Cushion Defects), Coarctation of the aorta, Ebstein anomaly, Hypoplastic left heart
syndrome, PATHOPHYSIOLOGY, Questions, Teaching Points:, Tetralogy of Fallot, The EKG, The
chest radiograph, The clinical features, Total anomalous pulmonary venous return (TAPVR),
Transposition of the great vessels, Treatment, Tricuspid atresia, Truncus arteriosus, Ventricular
septal defects (VSD), atrial septal defects (ASD), and patent ductus arteriosus (PDA), patent
ductus arteriosus (PDA)
Acyanotic Congenital Heart
Disease
Heart and Main Vessels
A 4 year old male presents in the office for a preschool physical examination. In the course of the
interview, his mother mentions that he seems to get short of breath with exercise recently. It is
especially noticeable during his swimming lessons when he tires before the other children do in his class.
He has otherwise been in good health since his last physical exam in the previous year. His records for
the past year show 3 office visits for minor upper respiratory illnesses, and no emergency room visits.
He has never had wheezing during his colds.
Exam: T37.5, P92, R25, BP right arm 97/70, oxygen saturation 98% in room air. Height and weight are
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Exam: T37.5, P92, R25, BP right arm 97/70, oxygen saturation 98% in room air. Height and weight are
at the 25th percentile. He is cooperative and well nourished in no distress. HEENT and neck exams are
normal. His chest is symmetrical. Heart: No palpable thrill, normal 1st and 2nd heart sounds; no clicks or
rubs; grade 1/6 ejection systolic murmur heard along the left sternal border with radiation to the back
between the scapulae; no diastolic murmur. Lungs are clear to auscultation. Abdomen without no
organomegaly or masses palpable. Genitalia: normal male. Extremities: Femoral pulses are slightly
diminished to palpation; no peripheral edema, clubbing or cyanosis of the nail beds. His neurological is
normal.
He receives his immunizations, and tuberculin skin test, and because of the new onset heart murmur,
a chest x-ray and EKG are ordered. He returns in 3 days to have his skin test read and to review his
cardiac tests. Before entering the exam room the nurse remeasures his vital signs and records in his
chart: BP left arm 127/86, P88, R24. His chest x-ray shows a cardiac/thoracic ratio of 0.55, normal
cardiac configuration, and normal pulmonary vasculature. His EKG has tall R waves of 40 mm in lead V5,
and 35 mm in lead V6. An echocardiogram is performed the following day and demonstrates a
coarctation of the aorta, and bicuspid aortic valve. A MRI shows a discrete narrowing of the distal aortic
arch just beyond the origin of the left subclavian artery and also reveals an aberrant right subclavian
artery originating from the proximal descending aorta below the coarctation.
Coarctation of the aorta
Coarctation of the aorta is classified as an acyanotic congenital heart defect and belongs to that group
of cardiac anomalies that is the result of abnormal fetal cardiac formation, that does NOT cause shunting
of blood from the venous to the systemic side of the heart (i.e., it does NOT cause right to left shunting),
and that may be manifested and clinically detectable some time after birth. With the advent of fetal
echocardiography, these lesions are sometimes detected before birth.
A list of the acyanotic lesions can be made by enumerating the structures encountered by the flow of
blood through the different parts of the heart beginning with the venous side. The most common
anomalies would thus include: tricuspid valve stenosis/regurgitation, Ebstein's anomaly of the tricuspid
valve (can be cyanotic in infants), pulmonic valve stenosis/regurgitation, subvalvular and supravalvular
pulmonic stenosis, partial anomalous pulmonary venous drainage to the right side of the heart, atrial
septal defect (secundum, primum, sinus venosus), mitral valve stenosis/regurgitation, ventricular septal
defect, aortic valve stenosis/regurgitation, subvalvular and supravalvular aortic stenosis, patent ductus
arteriosus, and coarctation of the aorta.
Acyanotic congenital lesions account for 70% of all congenital heart disease, the most common of
which, as isolated lesions, are ventricular septal defects (most common), patent ductus arteriosus, atrial
septal defect and pulmonic stenosis. Coarctation of the aorta accounts for (6%) of all congenital heart
disease. Patients with Turner syndrome have coarctation more commonly than the general population.
Coarctation of the aorta results from constriction of the tissue of the distal aortic arch at the junction
with the descending aorta and near the insertion of the ductus arteriosus. Various theories have been
proposed to explain this maldevelopment. One popular theory associates the presence of ductal tissue
encircling the aorta at the site of the coarctation suggesting a constrictive effect of the ductile tissue .
Although present at birth, coarctation of the aorta may not cause symptoms until early childhood and
sometimes not until late childhood, depending on the severity of the coarctation, and the presence of
associated cardiac lesions. If a ventricular septal defect is also present and is large, the coarctation of
the aorta will cause increased left to right shunting across the defect, producing congestive heart failure
within the first few months of life as the pulmonary resistance decreases after birth. A patent ductus
arteriosus located proximal to the coarctation would likewise increase pulmonary shunting through the
ductus resulting in congestive heart failure. If the ductus is located distal to the coarctation, signs and
symptoms may be delayed.
Other anomalies associated with aortic coarctation include a bicuspid aortic valve (85%) that may
obstruct left ventricular output, and an aberrant origin of the right subclavian artery distal to the
coarctation (1%). The latter will cause the blood pressure of the right arm to be equal to the leg, and may
mislead one from the correct diagnosis. It is important to measure the blood pressure in both arms and
at least one leg in order to detect the blood pressure differential caused by an aortic coarctation.
If coarctation of the aorta is an isolated lesion, the typical symptoms may include: shortness of breath
with exertion, leg pain with exercise, and rarely, chest pain with exercise. Physical findings include: upper
extremity hypertension with a blood pressure differential between arm and leg (obtain BP in both arms
and one leg), a systolic murmur heard along the left sternal border and especially well over the back
between the scapulae, and diminished and delayed pulses in the lower extremities when compared with
the upper extremities. A chest x-ray may display cardiomegaly with a left ventricular hypertrophy
configuration. In long standing cases, rib notching due to erosion of the lower anterior portion of the rib
by dilated collateral arteries can be appreciated. The echocardiogram demonstrates narrowing of the
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distal aortic arch with increased velocities on pulsed and color Doppler. The pulsed Doppler waveform has
a typical prolonged systolic phase extending throughout systole. The MRI produces a static but clearer
picture, than the echocardiogram, of the anatomy of the coarctation. An angiogram is sometimes
necessary to clarify associated cardiac lesions.
There are several surgical techniques used to repair a coarctation of the aorta. Each technique has
had its own proponents at one time or another. If the coarcted segment is short and discrete, resection
and end to end anastomosis of the proximal and distal ends is possible. If the coarctation is a long
tubular obstruction, resection with interposition of a tube graft would be necessary. Some surgeons favor
a longitudinal incision with insertion of a synthetic graft to enlarge the diameter. In the young infant,
sacrificing the left subclavian artery, and using the transected blood vessel as a graft by turning it down
and sewing it into the aortic wall was popular at one time.
Catheter balloon dilatation of native coarctations has not been as successful as dilatation of
postoperative restenosis of a coarctation. The former technique has resulted in late appearance of
aneurysms. The use of stents to reinforce the arterial wall is now preferred to balloon dilation alone.
Balloon Angioplasty
A postoperative complication that is now rare is the syndrome of mesenteric arteritis, caused by reflex
spasm of mesenteric arteries that are suddenly exposed to higher pressures after the coarctation is
removed. The spasm can be severe enough to result in bowel ischemia. Patients are being operated on
at a younger age now so that the mesenteric arteries do not have as long a period of exposure to low
pressures and are therefore less reactive.
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Ventricular septal defects (VSD), atrial septal defects (ASD), and patent ductus arteriosus (PDA)
account for a large percentage of all congenital heart defects. They share common physiologic
hemodynamics and will be discussed together.
Ventricular septal defects (VSD)
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These defects represent abnormal communications between the high pressure left side of the heart
and the low pressure right side of the heart. The pressure differential results in a left-to-right shunting of
blood through the defect. The consequences of this shunting of blood are: turbulence of abnormal blood
flow producing a heart murmur in systole and sometimes in diastole; excessive blood flow into the lungs
causing shortness of breath and increased pulmonary vascularity on a chest x-ray; and increased volume
overload of the myocardium resulting in hypertrophy of myocardium and chamber dilatation.
The murmur of a VSD is located at the lower left sternal border and is dictated by the anatomic
location of the defect in relation to the chest wall. Since flow across the VSD occurs as long as there is a
pressure differential between left and right ventricles, the timing of the murmur in this lesion is
pansystolic. The high pressure turbulence of the shunted blood produces a harsh quality to the murmur.
When the pulmonic flow exceeds the systemic flow by a ratio of 2:1, an apical diastolic murmur is
produced due to excessive flow during recirculation across the mitral valve. Frequently, a VSD murmur is
not heard at birth (day 1 of life) since pulmonary vascular resistance and pulmonary pressure may still be
high, limiting left to right shunting through the VSD. As pulmonary vascular resistance drops further,
more left to right shunting through the VSD occurs, making the murmur audible on day 2 or day 3 of life.
The murmur of an ASD is produced by excessive flow across the pulmonic and tricuspid valves
resulting in a systolic murmur at the second left intercostal space and a mid-diastolic murmur over the
lower right sternal area. Note that this is a flow murmur and NOT a murmur due to turbulent flow across
the ASD. Flow across the ASD is low velocity and not turbulent and therefore produces no audible
murmur itself.
The flow through a PDA is continuous due to the existence of a constant pressure differential between
aorta and pulmonary artery in both systole and diastole. The machinery quality of the murmur results
from the rhythmic variation of the pressure differentiation during the cardiac cycle. The location of the
murmur is at the upper left sternal border.
A small shunt produces only a murmur but no symptoms. With increasing defect size and pulmonary
flow, signs and symptoms of congestive heart failure occur: shortness of breath with exertion and in
severe cases, also at rest; cough and susceptibility to pulmonary infections; hepatomegaly,
splenomegaly, and lower extremity edema result from retrograde extension of the systemic venous
congestion into the liver, spleen and legs.
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The chest x-ray in a left-to-right shunt lesion will demonstrate congested pulmonary vessels.
Enlargement of specific cardiac chambers is due to excessive volume overload. The left atrium and
ventricle are dilated in VSD and PDA, and the right heart chamber is dilated in ASD. The EKG reveals
hypertrophy of the corresponding cardiac chambers.
patent ductus arteriosus (PDA)
Untreated defects with large shunts will eventually result in injury to the pulmonary arterioles, vascular
obstruction, and pulmonary hypertension. The development of permanent injury to the pulmonary
vessels is a function of the duration of the exposure to excessive blood flow and the anatomy, occurring
more rapidly in VSD and PDA than in ASD. If this process is not reversed, Eisenmenger's complex of right
to left shunting may occur as the right sided pressures (pulmonary hypertension) exceeds left sided
pressures.
Intracardiac repair of a VSD and ASD require cardiopulmonary bypass. Repair of a PDA is extracardiac
and is achieved without cardiopulmonary bypass. The intracardiac defects can be closed by primary
suturing of the edges of the defect if small, or by covering with a patch material if large. The PDA is
usually tied off and divided.
Complete heart block secondary to injury to the conduction system during repair of a VSD may require
a pacemaker in the postoperative period. The knowledge of the location of the conduction system in
relationship to the defect now makes this a rare complication. The mortality rate in experienced hands
should be less than 5% if all ages are considered, with infants carrying a higher mortality rate especially if
pulmonary hypertension is present.
Questions
1. 1. True/False: Congenital heart disease is always detectable at birth.
2. 2. True/False: Equal blood pressures in the right arm and left leg rule out the diagnosis of
coarctation of the aorta.
3. 3. Which are the three most common acyanotic congenital heart lesions?
4. 4. True/False: The presence of palpable femoral pulses rules out the diagnosis of aortic coarctation.
5. 5. True/False: Surgical repair of PDA does not require cardiopulmonary bypass.
6. 6. Explain how a child with an isolated VSD (classified as an acyanotic lesion) could become
cyanotic?
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7. 7. True/False: Medical students and residents will typically not hear the murmur of a VSD during
the initial newborn assessment in the nursery because the murmur of a VSD is subtle and low
pitched.
Answers to questions
1. 1. False. The physiologic pulmonary hypertension present in a newborn can prevent blood flow
across a septal defect or PDA. These can be detected several hours after birth or several days
after birth. Other congenital heart disease lesions may remain occult for longer period of time.
2. 2. False. An aberrant right subclavian artery originating below a coarctation will produce equal
pressures in the right arm and leg.
3. 3. VSD, ASD, PDA. Of these, VSD is the most common.
4. 4. False. Development of collateral vessels to the lower body can produce palpable femoral
pulses.
5. 5. True.
6. 6. Congestive heart failure and pulmonary edema may cause hypoxia. If the hypoxia is severe
enough, visible cyanosis will result, although this can be overcome with oxygen and other
treatments for pulmonary edema and congestive heart failure. Long standing excessive
pulmonary blood flow leads to pulmonary hypertension and Eisenmenger's complex, right to left
shunting and cyanosis.
7. 7. False. They cannot hear the murmur of a VSD on day 1 because on day 1, pulmonary vascular
resistance is still high, which restricts left to right flow through the VSD. On day 2, pulmonary
vascular resistance is lower, so left to right shunting through the VSD increases making the
murmur louder.
This is a 7 week old term female infant who presented with wheezing, coughing, and two episodes of nonbilious emesis. She was seen by her pediatrician, who suspected that she had bronchiolitis, and she was
treated with oral albuterol syrup. An RSV (Respiratory Syncytial Virus) nasal prep
was done, and this was negative; however, the patient's condition worsened, and she was brought to
the Emergency Department later that evening.
Exam: VS T37.2R, P168, R70, BP126/86, oxygen saturation 96% on room air. The infant was fussy,
though consolable, with moderate respiratory distress. She was non-toxic in appearance. The anterior
fontanelle was soft and flat. The pupils were equal and reactive and the mucus membranes were moist.
The neck was supple. The lungs had diffuse wheezes and crackles bilaterally with intercostal retractions.
Heart sounds were difficult to auscultate due to the noisy breathing, but no obvious loud pathologic
murmur was heard. The abdomen was soft and nontender with active bowel sounds. The liver edge was
palpated 3-4 cm below the right costal margin. Capillary refill time in the extremities was 3 seconds.
The patient was placed on supplemental oxygen and a CXR was obtained.
View CXR image.
The CXR showed cardiomegaly and possibly increased pulmonary vascular markings consistent with
congestive heart failure (CHF). The femoral pulses were difficult to palpate. Measurement of blood
pressures in the four extremities showed 126/86 (left arm), 132/92 (right arm), 69/41 (left leg), and 63/59
(right leg).
An EKG was done.
View EKG.
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It is not easy to see the tracing of some of the precordial leads ecause they are very large. R2 (R wave
of V2) extends into the tracing of V1. R4 is off the scale. Suffice it to say that all the R and S waves in
V1-V6 are large. The axis of QRS is 90 degrees (roughly isoelectric in I and positive in AVF). This is a
rightward axis. The large QRS's in V1-V6 meet voltage criteria for both LVH and RVH. This EKG shows
biventricular hypertrophy.
The patient was treated with furosemide, 1 mg/kg IV, and dobutamine, 5 mcg/kg/min as a continuous
infusion, with marked improvement in respiratory status.
The infant was admitted to the Pediatric Intensive Care Unit, and a cardiology consultation was
obtained.
An echocardiogram showed severe coarctation of the aorta, with a tight posterior shelf distal to the
left subclavian artery. The left ventricle was dilated with markedly decreased function. The patient
subsequently underwent operative repair of the coarctation, with an uneventful postoperative course.
Teaching Points:
1. Wheezing and respiratory distress are a common presentation of CHF in infants. Tachypnea alone
may be the earliest sign. Even in the midst of the busy winter bronchiolitis season, the clinician must be
careful to consider that the infant with wheezing and tachypnea may be a presentation of CHF, rather
than bronchiolitis. Physical exam findings of hepatomegaly or a gallop rhythm may aid in making the
proper diagnosis. Parents may also give a history of poor feeding, slow weight gain, and increased
sweating. A CXR showing cardiomegaly and increased pulmonary vascular markings will help to confirm
the diagnosis.
2. Coarctation of the aorta may present at an early age, as in this case, with progressive CHF. More
than 80% of infants with preductal COA develop CHF by 3 months of age. Coarctation of the aorta may
also present in the first one or two weeks of life with a sudden state of shock with CHF and
cardiovascular collapse when the ductus arteriosus closes (duct-dependent lesion). This is also the
typical presentation of the hypoplastic left heart syndrome.
Other types of congenital heart disease which may present early in infancy with CHF include large
ventricular septal defects, a large patent ductus
arteriosus, anomalous left coronary artery, and critical aortic or pulmonary stenosis. Acquired causes
of CHF in young infants include viral myocarditis and supraventricular tachycardia.
3. COA can range in severity from very slight with minimal physiologic consequence to severe aortic
coarctation or hypoplasia. More severe COA tends to present in infancy while less severe COA may
present in later childhood or adolescence. The CXR of the young infant presenting with severe COA
typically demonstrates cardiomegaly and increased pulmonary vascular markings (CHF). This is in
contrast to the CXR of COA presenting later in childhood, which typically shows a normal or only slightly
enlarged heart,
and normal pulmonary vascular markings. Rib notching, although pathognomonic for COA, is rarely
seen in children younger than 9 years of age. The aorta may develop dilation pre and post coarctation
resembling a "3" (3 sign) when viewing the right side of the aorta on an overpenetrated film. If a barium
swallow is performed the pre and post coarctation dilation of the aorta impinges upon the esophagus
to it giving an "E" appearance to this area of the esophagus (E sign). These signs are not generally seen
on routine views that would be ordered in the E.D.
4 . Treatment of CHF in infancy requires attention to the cardinal ABCs of emergency medicine
(Airway, Breathing, Circulation). Administration of supplemental oxygen should be considered as a firstline therapy. If
the patient is unstable, intubation with positive-pressure ventilation may be required. To improve
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the patient is unstable,
intubation with positive-pressure ventilation may be required. To improve
cardiac contractility, inotropes such as digoxin or dobutamine may be needed. Dobutamine also has the
advantage of decreasing afterload. Diuretics such as furosemide aid by decreasing preload. In severe
cases, other vasoactive or inotropic agents such as sodium nitroprusside and amrinone may be
considered. These agents should be used in the intensive care unit, using invasive hemodynamic
monitoring. If a duct-dependent lesion is suspected, prostaglandin E1 should be started
as a continuous infusion at 0.1 mcg/kg/min.
This is 2-month old male who presents to the emergency department with a five day history of funny
breathing. He was well until 5 days prior when his mother noted noisy, rapid breathing and a tactile
temperature. Four days prior, he was taken to his private physician and was started on amoxicillin for
otitis media. His lung exam at that time was normal. Two days prior he was taken to the emergency
department and was noted to be wheezing. He was given an albuterol aerosol and was discharged on
oral albuterol. He continued to have breathing problems at home and now returns to the emergency
department since his condition has not improved. His birth history is unremarkable, and he has shown
adequate weight gain since birth. There are no reported feeding problems according to his mother. His
family history is significant for two siblings with asthma.
Exam: T36.9, P168, BP 98/60. His respiratory rate varies between 60 and 80 per minute. His oxygen
saturation is 97% in room air. His oxygen saturation improves to 100% on oxygen by nasal cannula at
2 liters per minute. He is a fussy infant with modest achypnea. Despite this, he does not appear to be in
significant distress. He is not toxic. He is noted to have mild retractions when crying, with bilaterally
coarse breath sounds without wheezes. Heart regular
without murmurs or gallops. Abdomen: Liver edge palpable 3 cm below the right costal margin.
A chest X-ray was obtained.
View CXR: AP view.
View CXR: Lateral view.
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Do you think this represents a pneumonia? The emergency department physician reads this as mild
perihilar infiltrates. A diagnostic impression of a viral pneumonia is made, and the infant is hospitalized
because of his young age and persistent tachypnea. The following morning, the radiologist reads the
chest radiograph as showing borderline cardiomegaly with prominence of the right atrium and increased
pulmonary vascularity. The right heart border appears to be prominent, but this initially was thought to
be due to rotational artifact. The diffuse reticular markings fanning out from the hilum suggest pulmonary
venous congestion but are difficult to distinguish from perihilar infiltrates. These findings are suggestive
of congenital heart disease. This radiographic information prompts a
cardiac work-up. The most important point here is to realize that a cardiac defect may be responsible
for the infant's respiratory symptoms. Scrutinizing the chest radiograph for subtle signs of cardiac
disease is
important since, once cardiac disease is suspected, it is a simple matter of obtaining an
echocardiogram.
After admission to the wards, the infant develops worsening respiratory distress. A blood gas is
obtained. On room air, an arterial blood gas shows pH 7.27, pCO2 35, pO2 76, HCO3 of 16. With 100%
O2, the pO2 increases to 138. An EKG shows right atrial enlargement with right axis deviation and right
ventricular hypertrophy. An echocardiogram shows a membranous structure in the left atrium, a high
atrial septal defect, and dilation of the right atrium and right ventricle. The right ventricular systolic
pressure is elevated to 103 mm Hg. The diagnosis of cor triatriatum with secondary congestive heart
failure is made, and the infant is started on digoxin and diuretics. He is referred to a cardiac surgeon for
corrective surgery and does well postoperatively.
A follow up chest radiograph taken a few months later shows a decrease in heart size and decreased
pulmonary congestion.
View follow-up CXR.
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Also present are surgical wires and metal clips in the area of the left atrium. There is some residual
prominence of the pulmonary vasculature.
Cor triatriatum is a rare congenital cardiac anomaly where the pulmonary veins enter an accessory
chamber that joins the left atrium through a narrow opening. This accessory chamber may also directly
communicate with the right atrium. In classical cor triatriatum, a membranous partition exists in the left
atrium in the shape of a wind sock.
View Cor Triatriatum diagram.
The upper chamber (XC) of this partition receives blood from the pulmonary veins, and the distal
chamber communicates with the mitral valve.
The orifice diameter of the windsock ranges from less than 3 mm
to about 1 cm. In a minority of cases, a patent foramen ovale or an atrial septal defect allows
communication with the right atrium. Right ventricular hypertrophy and dilation are almost always
present, and right atrial
dilation occurs 25% of the time. Current theories suggest that the defect occurs because the common
pulmonary vein fails to incorporate into the left atrium during cardiac embryogenesis.
The clinical features of this anomaly are related to the pulmonary congestion and hypertension
created by the membranous left atrial structure. When pulmonary venous blood flow becomes
obstructed, the lungs reflect varying degrees of pulmonary edema and intraalveolar hemorrhage.
Patients usually present within the first few years of life with a history of
shortness of breath and frequent pulmonary infections and audible rales. Signs of pulmonary
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hypertension, including a loud pulmonic component of the second heart sound, right ventricular heave
and pulmonary systolic ejection clicks are often present. The usual heart murmur is a soft,
blowing,systolic murmur heard best at the left sternal border.
The EKG usually reveals signs of right-sided heart overload such as right ventricular hypertrophy and
right atrial enlargement.
The chest radiograph often reveals pulmonary venous obstruction. Diffuse reticular pulmonary
markings fan out from the hilum to involve the lower lung fields. Kerley B lines may also be present. The
right heart border may reveal a double density suggestive of left atrial enlargement. Other findings
include enlargement of the main pulmonary artery and
right ventricular hypertrophy.
Treatment of this disease involves management of congestive heart failure. Once patients reach this
stage, they usually deteriorate fairly quickly despite medical management. Surgical intervention should
be planned as soon as possible in symptomatic patients once the diagnosis is made. The operation of
choice is usually correction under direct vision with cardiopulmonary bypass. The prognosis of cor
triatriatum is related to the size of the orifice in the obstructing membrane. Without surgical correction,
the average survival is about 3 months when the opening is less than 3 mm, and 16 years when the
opening is greater than 3 mm. In those patients surviving operative correction, the prognosis is excellent.
Acyanotic Congenital Heart Disease
The Left-to-Right Shunt Lesions
Atrial Septal Defect
Atrial septal defects (ASDs) can occur in any portion of the atrial septum (secundum, primum, or sinus
venosus), depending on which embryonic septal structure has failed to develop normally. Less
commonly, the atrial septum may be nearly absent, with the creation of a functional single atrium.
Isolated secundum ASDs account for ≈7% of congenital heart defects. The majority of cases of ASD are
sporadic; autosomal dominant inheritance does occur as part of the Holt-Oram syndrome (hypoplastic or
absent radii, 1st-degree heart block, ASD) or in families with secundum ASD and heart block.
An isolated valve-incompetent patent foramen ovale (PFO) is a common echocardiographic finding
during infancy. It is usually of no hemodynamic significance and is not considered an ASD; a PFO may
play an important role if other structural heart defects are present. If another cardiac anomaly is causing
increased right atrial pressure (pulmonary stenosis or atresia, tricuspid valve abnormalities, right
ventricular dysfunction), venous blood may shunt across the PFO into the left atrium with resultant
cyanosis. Because of the anatomic structure of the PFO, left-to-right shunting is unusual outside the
immediate newborn period. In the presence of a large volume load or a hypertensive left atrium
(secondary to mitral stenosis), the foramen ovale may be sufficiently dilated to result in a significant
atrial left-to-right shunt. A valve-competent but probe-patent foramen ovale may be present in 15–30%
of adults. An isolated PFO does not require surgical treatment, although it may be a risk for paradoxical
(right to left) systemic embolization. Device closure of these defects is considered in adults with a history
of thromboembolic stroke.
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Ostium Secundum Defect
An ostium secundum defect in the region of the fossa ovalis is the most common form of ASD and is
associated with structurally normal atrioventricular (AV) valves. Mitral valve prolapse has been described
in association with this defect but is rarely an important clinical consideration. Secundum ASDs may be
single or multiple (fenestrated atrial septum), and openings ≥2 cm in diameter are common in
symptomatic older children. Large defects may extend inferiorly toward the inferior vena cava and ostium
of the coronary sinus, superiorly toward the superior vena cava, or posteriorly. Females outnumber
males 3:1 in incidence. Partial anomalous pulmonary venous return, most commonly of the right upper
pulmonary vein, may be an associated lesion.
PATHOPHYSIOLOGY
The degree of left-to-right shunting is dependent on the size of the defect, the relative compliance of
the right and left ventricles, and the relative vascular resistance in the pulmonary and systemic
circulations. In large defects, a considerable shunt of oxygenated blood flows from the left to the right
atrium. This blood is added to the usual venous return to the right atrium and is pumped by the right
ventricle to the lungs. With large defects, the ratio of pulmonary to systemic blood flow (Qp : Qs) is
usually between 2 : 1 and 4 : 1. The paucity of symptoms in infants with ASDs is related to the
structure of the right ventricle in early life when its muscular wall is thick and less compliant, thus
limiting the left-to-right shunt. As the infant becomes older and pulmonary vascular resistance drops,
the right ventricular wall becomes thinner and the left-to-right shunt across the ASD increases. The
large blood flow through the right side of the heart results in enlargement of the right atrium and
ventricle and dilatation of the pulmonary artery. The left atrium may be enlarged, the left ventricle and
aorta normal in size. Despite the large pulmonary blood flow, pulmonary arterial pressure is usually
normal because of the absence of a high-pressure communication between the pulmonary and
systemic circulations. Pulmonary vascular resistance remains low throughout childhood, although it
may begin to increase in adulthood and may eventually result in reversal of the shunt and clinical
cyanosis.
19
Atrioventricular Septal Defects (Ostium Primum and Atrioventricular Canal or Endocardial Cushion Defects)
CLINICAL MANIFESTATIONS.
A child with an ostium secundum ASD is most often asymptomatic; the lesion may be discovered
inadvertently during physical examination. Even an extremely large secundum ASD rarely produces
clinically evident heart failure in childhood. In younger children, subtle failure to thrive may be present; in
older children, varying degrees of exercise intolerance may be noted. Often, the degree of limitation may
go unnoticed by the family until after surgical repair, when the child's growth or activity level increases
markedly.
The physical findings of an ASD are usually characteristic but fairly subtle and require careful
examination of the heart, with special attention to the heart sounds. Examination of the chest may
reveal a mild left precordial bulge. A right ventricular systolic lift is generally palpable at the left sternal
border. A loud 1st heart sound and sometimes a pulmonic ejection click can be heard. In most patients,
the 2nd heart sound is characteristically widely split and fixed in its splitting in all phases of
respiration. Normally, the duration of right ventricular ejection varies with respiration, with inspiration
increasing right ventricular volume and delaying closure of the pulmonary valve. With an ASD, right
ventricular diastolic volume is constantly increased and the ejection time is prolonged throughout all
phases of respiration. A systolic ejection murmur is heard; it is medium pitched, without harsh qualities,
seldom accompanied by a thrill, and best heard at the left middle and upper sternal border. It is
produced by the increased flow across the right ventricular outflow tract into the pulmonary artery, not by
low-pressure flow across the ASD. A short, rumbling mid-diastolic murmur produced by the increased
volume of blood flow across the tricuspid valve is often audible at the lower left sternal border. This
finding, which may be subtle and is heard best with the bell of the stethoscope, usually indicates a Qp :
Qs ratio of at least 2 : 1.
DIAGNOSIS.
The chest roentgenogram shows varying degrees of enlargement of the right ventricle and atrium,
depending on the size of the shunt. The pulmonary artery is large, and pulmonary vascularity is
increased. These signs vary and may not be conspicuous in mild cases. Cardiac enlargement is often
best appreciated on the lateral view because the right ventricle protrudes anteriorly as its volume
increases. The electrocardiogram shows volume overload of the right ventricle; the QRS axis may be
normal or exhibit right axis deviation, and a minor right ventricular conduction delay (rsR pattern in the
right precordial leads) may be present.
The echocardiogram shows findings characteristic of right ventricular volume overload, including an
increased right ventricular end-diastolic dimension and flattening and abnormal motion of the ventricular
septum. A normal septum moves posteriorly during systole and anteriorly during diastole. With right
ventricular overload and normal pulmonary vascular resistance, septal motion is reversed—that is,
anterior movement in systole—or the motion may be intermediate so that the septum remains straight.
The location and size of the atrial defect are readily appreciated by two-dimensional scanning, with a
characteristic brightening of the echo image seen at the edge of the defect (T-artifact). The shunt is
confirmed by pulsed and color flow Doppler. Patients with the classic features of a hemodynamically
significant ASD on physical examination and chest radiography, in whom echocardiographic identification
of an isolated secundum ASD is made, need not be catheterized before surgical closure, with the
exception of an older patient, in whom pulmonary vascular resistance may be a concern. If pulmonary
vascular disease is suspected, cardiac catheterization confirms the presence of the defect and allows
measurement of the shunt ratio and pulmonary pressure.
At catheterization, the oxygen content of blood from the right atrium will be much higher than that
from the superior vena cava. This feature is not specifically diagnostic because it may occur with partial
anomalous pulmonary venous return to the right atrium, with a ventricular septal defect (VSD) in the
20
Atrioventricular Septal Defects (Ostium Primum and Atrioventricular Canal or Endocardial Cushion Defects)
presence of tricuspid insufficiency, with AV septal defects associated with left ventricular to right atrial
shunts, and with aorta to right atrial communications (ruptured sinus of Valsalva aneurysm). Pressure in
the right side of the heart is usually normal, but small to moderate pressure gradients (<25 mm Hg)
may be measured across the right ventricular outflow tract because of functional stenosis related to
excessive blood flow. In children and adolescents, the pulmonary vascular resistance is almost always
normal. The shunt is variable and depends on the size of the defect, but it may be of considerable
volume (as high as 20 L/min/m 2). Cineangiography, performed with the catheter through the defect and
in the right upper pulmonary vein, demonstrates the defect and the location of the right upper
pulmonary venous drainage. Alternatively, pulmonary angiography demonstrates the defect on the
levophase (return of contrast to the left side of the heart after passing through the lungs).
COMPLICATIONS.
Secundum ASDs are usually isolated, although they may be associated with partial anomalous
pulmonary venous return, pulmonary valvular stenosis, VSD, pulmonary artery branch stenosis, and
persistent left superior vena cava, as well as mitral valve prolapse and insufficiency. Secundum ASDs are
associated with the autosomal dominant Holt-Oram syndrome. The gene responsible for this syndrome,
situated in the region 12q21–q22 of chromosome 12, is TBX5, a member of the T-box transcriptional
family. A familial form of secundum ASD associated with AV conduction delay has been linked to
mutations in another transcription factor, Nkx2.5. Patients with familial ASD without heart block may
carry a mutation in the transcription factor GATA4, located on chromosome 8p22–23.
TREATMENT.
Surgical or transcatheter device closure is advised for all symptomatic patients and also for
asymptomatic patients with a Qp : Qs ratio of at least 2 : 1. The timing for elective closure is usually after
the 1st yr and before entry into school. Closure carried out at open heart surgery is associated with a
mortality rate of <1%. Repair is preferred during early childhood because surgical mortality and morbidity
are significantly greater in adulthood; the long-term risk of arrhythmia is also greater after ASD repair in
adults. Atrial septal occlusion devices are implanted transvenously in the cardiac catheterization
laboratory ( Fig. 426-3 ). The results are excellent and patients are discharged the following day. With the
latest generation of devices, the incidence of serious complications such as device erosion is 0.1% and
can be decreased by identifying high-risk patients such as those with a deficient rim of septum around
the device. In patients with small secundum ASDs and minimal left-to-right shunts, the consensus is that
closure is not required. It is unclear at present whether the persistence of a small ASD into adulthood
increases the risk for stroke enough to warrant prophylactic closure of all these defects.
PROGNOSIS.
ASDs detected in term infants may close spontaneously. Secundum ASDs are well tolerated during
childhood, and symptoms do not usually appear until the 3rd decade or later. Pulmonary hypertension,
atrial dysrhythmias, tricuspid or mitral insufficiency, and heart failure are late manifestations; these
symptoms may initially appear during the increased volume load of pregnancy. Infective endocarditis is
extremely rare, and antibiotic prophylaxis for isolated secundum ASDs is not recommended.
The results after surgical or device closure in children with moderate to large shunts are excellent.
Symptoms disappear rapidly, and growth is frequently enhanced. Heart size decreases to normal, and
the electrocardiogram shows decreased right ventricular forces. Late right heart failure and arrhythmias
are less frequent in patients who have had early surgical repair, becoming more common in patients who
undergo surgery after 20 yr of age. Although early and midterm results with device closure are excellent,
the long-term effects are not yet known. Reports of resolution of migraine headaches in patients after
device closure of ASD or PFO are intriguing, suggesting a possible thromboembolic etiology; however,
there are also paradoxical reports of patients whose migraines began or worsened after placement of
one of these devices.
Atrioventricular Septal Defects
(Ostium Primum and
Atrioventricular Canal or
21
Cyanotic Congenital Heart Disease
Endocardial Cushion Defects)
The abnormalities encompassed by AV septal defects are grouped together because they represent a
spectrum of a basic embryologic abnormality, a deficiency of the AV septum. An ostium primum defect
is situated in the lower portion of the atrial septum and overlies the mitral and tricuspid valves. In most
instances, a cleft in the anterior leaflet of the mitral valve is also noted. The tricuspid valve is usually
functionally normal, although some anatomic abnormality of the septal leaflet is generally present. The
ventricular septum is intact.
An AV septal defect, also known as an AV canal defect or an endocardial cushion defect, consists
of contiguous atrial and ventricular septal defects with markedly abnormal AV valves. The severity of the
valve abnormalities varies considerably; in the complete form of AV septal defect, a single AV valve is
common to both ventricles and consists of an anterior and a posterior bridging leaflet related to the
ventricular septum, with a lateral leaflet in each ventricle. The lesion is common in children with Down
syndrome and may occasionally occur with pulmonary stenosis.
Transitional varieties of these defects also occur and include ostium primum defects with clefts in the
anterior mitral and septal tricuspid valve leaflets, minor ventricular septal deficiencies, and, less
commonly, ostium primum defects with normal AV valves. In some patients, the atrial septum is intact,
but the inlet VSD simulates that found in the full AV septal defect. These defects are also commonly
associated with deformities of the AV valves. Sometimes AV septal defects are associated with varying
degrees of hypoplasia of one of the ventricles, known as either left- or right-dominant AVSD. If the
affected ventricular chamber is too small, then surgical palliation, aiming for an eventual Fontan
procedure, is similar to that for hypoplastic left or right heart syndromes.
PATHOPHYSIOLOGY.
The basic abnormality in patients with ostium primum defects is the combination of a left-to-right
shunt across the atrial defect and mitral (or occasionally tricuspid) insufficiency. The shunt is usually
moderate to large, the degree of mitral insufficiency is generally mild to moderate, and pulmonary
arterial pressure is typically normal or only mildly increased. The physiology of this lesion is therefore
similar to that of an ostium secundum ASD.
In AV septal defects, the left-to-right shunt occurs at both the atrial and ventricular levels. Additional
shunting may occur directly from the left ventricle to the right atrium because of absence of the AV
septum. Pulmonary hypertension and an early tendency to increase pulmonary vascular resistance are
common. AV valvular insufficiency increases the volume load on one or both ventricles. Some right-toleft shunting may also occur at both the atrial and ventricular levels and lead to mild but significant
arterial desaturation. With time, progressive pulmonary vascular disease increases the right-to-left shunt
so that clinical cyanosis develops.
CLINICAL MANIFESTATIONS.
Many children with ostium primum defects are asymptomatic, and the anomaly is discovered during a
general physical examination. In patients with moderate shunts and mild mitral insufficiency, the physical
signs are similar to those of the secundum ASD, but with an additional apical murmur caused by mitral
insufficiency.
A history of exercise intolerance, easy fatigability, and recurrent pneumonia may be obtained,
especially in infants with large left-to-right shunts and severe mitral insufficiency. In these patients,
cardiac enlargement is moderate or marked, and the precordium is hyperdynamic. Auscultatory signs
produced by the left-to-right shunt include a normal or accentuated 1st sound; wide, fixed splitting of the
2nd sound; a pulmonary systolic ejection murmur sometimes preceded by a click; and a low-pitched,
mid-diastolic rumbling murmur at the lower left sternal edge or apex, or both, as a result of increased
flow through the AV valves. Mitral insufficiency may be manifested by a harsh (occasionally very high
pitched) apical holosystolic murmur that radiates to the left axilla.
With complete AV septal defects, heart failure and intercurrent pulmonary infection usually appear in
infancy. During these episodes, minimal cyanosis may be evident. The liver is enlarged and the infant
shows signs of failure to thrive. Cardiac enlargement is moderate to marked, and a systolic thrill is
frequently palpable at the lower left sternal border. A precordial bulge and lift may be present as well. The
1st heart sound is normal or accentuated. The 2nd heart sound is widely split if the pulmonary flow is
massive. A low-pitched, mid-diastolic rumbling murmur is audible at the lower left sternal border, and a
pulmonary systolic ejection murmur is produced by the large pulmonary flow. The harsh apical
holosystolic murmur of mitral insufficiency may also be present.
DIAGNOSIS.
Chest radiographs of children with complete AV septal defects often show moderate to severe cardiac
enlargement caused by the prominence of both ventricles and atria. The pulmonary artery is large, and
pulmonary vascularity is increased.
The electrocardiogram in patients with a complete AV septal defect is distinctive. The principal
abnormalities are (1) superior orientation of the mean frontal QRS axis with left axis deviation to the left
upper or right upper quadrant, (2) counterclockwise inscription of the superiorly oriented QRS vector loop,
(3) signs of biventricular hypertrophy or isolated right ventricular hypertrophy, (4) right ventricular
conduction delay (RSR′ pattern in leads V3R and V1), (5) normal or tall P waves, and (6) occasional
prolongation of the P-R interval. shows signs of right ventricular enlargement with encroachment of the
mitral valve echo on the left ventricular outflow tract; the abnormally low position of the AV valves results
in a “gooseneck” deformity of the left ventricular outflow tract on both echocardiography and
angiography. In normal hearts, the tricuspid valve inserts slightly more toward the apex than the mitral
valve does. In AV septal defects, both valves insert at the same level because of absence of the AV
septum. In complete AV septal defects, the ventricular septal echo is also deficient and the common AV
valve is readily appreciated. Pulsed and color flow Doppler echocardiography will demonstrate left-to-right
shunting at the atrial, ventricular, or ventricular to atrial levels and semiquantitate the degree of AV valve
22
Cyanotic Congenital Heart Disease
insufficiency. Echocardiography is useful for determining the insertion points of the chordae of the
common AV valve and for evaluating the presence of associated lesions such as patent ductus
arteriosus (PDA) or coarctation of the aorta.
Selective left ventriculography will demonstrate deformity of the mitral or common AV valve and the
distortion of the left ventricular outflow tract caused by this valve (“gooseneck” deformity). The abnormal
anterior leaflet of the mitral valve is serrated, and mitral insufficiency is noted, usually with regurgitation
of blood into both the left and right atria. Direct shunting of blood from the left ventricle to the right
atrium may also be demonstrated.
TREATMENT.
Ostium primum defects are approached surgically from an incision in the right atrium. The cleft in the
mitral valve is located through the atrial defect and is repaired by direct suture. The defect in the atrial
septum is usually closed by insertion of a patch prosthesis. The surgical mortality rate for ostium primum
defects is very low. Surgical treatment of complete AV septal defects is more difficult, especially in
infants with cardiac failure and pulmonary hypertension. Because of the risk of pulmonary vascular
disease developing as early as 6–12 mo of age, surgical intervention must be performed during infancy.
Correction of these defects can be accomplished in infancy, and palliation with pulmonary arterial
banding is reserved for the subset of patients who have other associated lesions that make early
corrective surgery too risky. The atrial and ventricular defects are patched and the AV valves
reconstructed. Complications include surgically induced heart block requiring placement of a permanent
pacemaker, excessive narrowing of the left ventricular outflow tract requiring surgical revision, and
eventual worsening of mitral regurgitation requiring replacement with a prosthetic valve.
PROGNOSIS.
The prognosis for unrepaired complete AV septal defects depends on the magnitude of the left-toright shunt, the degree of elevation of pulmonary vascular resistance, and the severity of AV valve
insufficiency. Death from cardiac failure during infancy used to be frequent before the advent of early
corrective surgery. In patients who survived without surgery, pulmonary vascular obstructive disease or,
more rarely, pulmonic stenosis usually developed. Most patients with ostium primum defects and
minimal AV valve involvement are asymptomatic or have only minor, nonprogressive symptoms until
they reach the 3rd–4th decade of life, similar to the course of patients with secundum ASDs. Late
postoperative complications include atrial arrhythmias and heart block, progressive narrowing of the left
ventricular outflow tract requiring surgical revision, and eventual worsening of atrioventricular valve
regurgitation (usually on the left side) requiring replacement with a prosthetic valve.
Cyanotic Congenital Heart Disease
This is a 3 month old male infant who presents to the emergency department with a history of having
episodes of excessive crying followed by limpness, cyanosis and fainting. He was born at 41 weeks of
gestation by C-section because of failure to progress to a 23 year old mother G1P0. Apgar scores of 7
and 8 at 1 and 5 minutes, respectively. He had a two vessel cord and acrocyanosis. His cyanosis
increased with crying and he had a grade 3/6 ejection systolic murmur along the upper left sternal
border (ULSB). His oxygen saturations were 95% and stable. He was discharged from the hospital and
followed in the office until this episode. He is now being hospitalized.
Exam: VS T 37, P164, RR 64, oxygen saturation 83% on oxygen by nasal prongs. Weight 50th
percentile. He is alert and active in mild respiratory distress, with visible cyanosis. HEENT exam is
negative. His heart rhythm is tachycardic. He has a mild right precordial heave with a grade 3/6 ejection
murmur at ULSB and a diminished 2nd heart sound. His lungs are clear. Liver and spleen are not
enlarged. He has normal peripheral pulses with cyanotic nail beds and mucous membranes.
An echocardiogram is obtained which identifies cyanotic congenital heart disease. This is confirmed at
cardiac catheterization. He subsequently undergoes palliative surgery with improved oxygenation and
appearance of a continuous murmur. He is discharged in stable condition to be followed on an outpatient
basis and to undergo further corrective surgery at a later date.
23
Cyanotic Congenital Heart Disease
This diagram of the adult heart illustrates the structures that are affected by congenital heart
diseases, with the estimated incidence of each disease per 1,000 live births indicated in parentheses. AC,
aortic coarctation; AS, aortic stenosis; ASD, atrial septal defect; AVSD, atrioventricular septal defect;
BAV, bicuspid aortic valve; DORV, double outlet right ventricle; Ebstein's, Ebstein's anomaly of the
tricuspid valve; HLHS, hypoplastic left heart syndrome; HRHS, hypoplastic right heart; IAA, interrupted
aortic arch; MA, mitral atresia; MS, mitral stenosis; PDA, patent ductus arteriosus; PS, pulmonary artery
stenosis; PTA, persistent truncus arteriosus; TA, tricuspid atresia; TAPVR, total anomalous pulmonary
venous return; TGA, transposition of the great arteries; TOF, tetralogy of Fallot; VSD, ventricular septal
defect. (Image courtesy of F. Yeung, University of Toronto, Canada.)
Cyanosis is a bluish discoloration of skin and mucous membranes. It results from reduced hemoglobin
in blood of at least 3-5 gm/dL. Cyanosis can be secondary to cardiac, respiratory, hematologic and
metabolic causes. Methemoglobinemia, decreased alveolar hypoventilation secondary to depressed
respiratory center or obstruction of the respiratory passages, polycythemia, and hypoglycemia, shock,
and sepsis may also cause cyanosis, or at least something that resembles cyanosis. It can be central or
peripheral. Peripheral cyanosis is secondary to low cardiac output, in which acrocyanosis usually occurs
with cool extremities and small pulse volume with bluish discoloration at the tip of the nose and fingers,
and less in the mucous membranes. It is often difficult to differentiate pulmonary from cardiac causes of
cyanosis in the newborn. A hyperoxy test may be helpful, whereby an arterial pO2 is measured in room
air, which is then compared to a arterial pO2 measured in an FiO2 of about 90%-100% for about 10-15
minutes. Respiratory problems with alveolar hypoventilation usually improve with paO2 measurements
well above 100-150 mmHg, whereas in right-to-left shunt cardiac lesions, the improvement in arterial
pO2 is very minimal. Echocardiogram and chest x-ray are useful in differentiating these causes.
The above mentioned case represents a diagnostic and management problem. Classifying cyanotic
congenital heart defects into those with increased vascularity with an accentuated second heart sound
and those with decreased blood flow with a diminished second heart sound, can simplify the differential
diagnosis to an extent. Chest x-ray findings and attention to the second heart sound may help. Lesions
with increased or normal blood flow with accentuated second heart sounds include transposition of the
great vessels, truncus arteriosis, total anomalous pulmonary venous return, single ventricle, single
atrium, and hypoplastic left heart. Eisenmenger syndrome also falls into this category, but this is an
acquired condition in which a patient with a left-to-right shunt and chronic CHF develops pulmonary
hypertension and a subsequent right-to-left shunt. Those lesions with decreased blood flow and
diminished second heart sound include tetralogy of Fallot or tetralogy of Fallot-like lesions, pulmonary
atresia, tricuspid atresia, and Ebstein's malformation.
24
Cyanotic Congenital Heart Disease
In the diagram above, transposition of the great vessels is shown. This occurs when the trunco-conal
septum does not spiral down. Instead, it descends straight down. As a result, the outflow of right ventricle
is into the aorta and the outflow from the left ventricle is into the pulmonic trunk.In order for this system
to work, there must be a connection between the system and pulmonic circulations. Sometimes this is
through a ventricular septal defect or an atrial septal defect. In the diagram at the left, this is through a
patent ductus arteriosus.
Transposition of the great vessels is the most common cyanotic congenital heart disease in the
newborn infant (tetralogy of Fallot is more common overall, but many tetralogy of Fallot cases present
after the newborn period). Transposition represents 4%-5% of all congenital heart defects. The aorta
arises from the right ventricle and pulmonary artery from the left ventricle, with the aorta positioned
anterior and to the right of the pulmonary artery. It is incompatible with life unless a communication
exists between systemic and pulmonary circulation, as the two circulations are in parallel (and
independent). During the newborn period, the PDA and patent foramen ovale (PFO) maintain this
communication. As the PDA starts to close and the PFO by itself is inadequate in size, the patient
develops intense cyanosis, and the patient becomes tachypneic. On auscultation, the second heart
sound is greater in intensity, as the aortic valve is anterior. A heart murmur may not be present unless
other associated lesions are present. An electrocardiogram may show right ventricular hypertrophy, but
this is non-specific since RVH is present in normal newborns. Chest x-ray shows increased pulmonary
vascular markings and a narrow mediastinal shadow secondary to a small thymus, sometimes giving the
appearance of "egg on side" or "apple on a string" appearance. Echocardiography confirms the diagnosis
and delineates the other associated lesions. Inadequate mixing between systemic and pulmonary circuits
represents a medical emergency and a prostaglandin E1 infusion which maintains ductus arteriosus
patency (to preserve mixing) may be lifesaving, followed by balloon atrial septostomy (Rashkind
procedure). Surgical management consists of an arterial switch procedure (aorta and pulmonary artery
are anastomosed to the correct ventricle), which is the operation of choice. The atrial switch (atrial
baffling) such as Senning or Mustard procedures are no longer done because of the development of later
complications. Survival without surgery is unlikely. The arterial switch procedure offers the best prognosis
with a mortality of about 5%.
25
Cyanotic Congenital Heart Disease
This diagram depicts the features of Tetralogy of Fallot:1. Ventricular septal defect; 2. Overriding aorta;
3. Pulmonic stenosis; 4. Right ventricular hypertrophy. The obstruction to right ventricular outflow creates
a right-to-left shunt that leads to cyanosis.
Tetralogy of Fallot constitutes 4%-9% of congenital heart disease and is the most common cyanotic
congenital heart disease when considering all age groups together. Tetralogy of Fallot and pulmonary
atresia with ventricular septal defect consist of: a) ventricular septal defect, b) pulmonary stenosis, c)
overriding of the aorta, and d) right ventricular hypertrophy. Approximately 25% have a right-sided aortic
arch, and about 4% have a coronary artery anomaly. The degree of cyanosis depends on the degree of
pulmonic outflow obstruction. This is quite variable, from a slight obstruction, to severe obstruction with
pulmonary atresia. Pulmonary atresia constitutes about 18% of the children with tetralogy of Fallot . The
major right ventricular outflow obstruction in tetralogy of Fallot is infundibular stenosis. With mild stenosis,
there may be congestive heart failure in infancy, also known as "pink tetralogy of Fallot." As infundibular
stenosis increases, progressive cyanosis develops (due to less pulmonary blood flow), and infants and
children may develop cyanotic or hypoxic spells, which consist of sudden onset of increased cyanosis,
excessive crying, hypoxemia, acidosis, dyspnea, fainting, rarely seizures, and occasionally death if
untreated. During these episodes (called "Tet" spells), there is increased right-to-left shunting (with less
pulmonary flow), and decreased systemic vascular resistance. Older infants and children may assume a
squatting position during playtime or long walks which increases systemic vascular resistance and
decreases right to left shunting, increasing their oxygenation.
Clinical examination shows a loud systolic ejection murmur from the right ventricular outflow
obstruction at the left sternal border conducted to the upper sternal border towards the suprasternal
notch. The second pulmonary sound may be diminished, but the aortic component may be loud, as the
aorta is anterior.
26
Cyanotic Congenital Heart Disease
The electrocardiogram shows the non-specific right ventricular hypertrophy. Chest x-ray shows
decreased pulmonary vascular markings (reduced pulmonary perfusion) and right ventricular
hypertrophy with a leftward apex. There is an absence or decreased main pulmonary artery segment,
which may give the appearance of a "boot shaped heart." Echocardiography demonstrates a ventricular
septal defect with an overriding of the aorta, pulmonic stenosis, right ventricular hypertrophy, and in
about 25% of cases, a right aortic arch (i.e., the aorta goes over the right mainstem bronchus instead of
the left) is also present. Cardiac catheterization is done in cases in which the anatomy of the defect is
not clear on echocardiogram.
Management during the newborn period consists of administration of prostaglandin E1 when the infant
is markedly cyanotic and pulmonary blood flow is ductus dependent. This is followed by a systemic artery
to pulmonary artery shunt (Blalock-Taussig shunt). Treatment of hypercyanotic spells is directed towards
improving pulmonary blood flow. These include oxygen, knee/chest position, morphine, intravenous fluids,
sodium bicarbonate, propranolol (beta-blocker), or increasing systemic vascular resistance by
administration of drugs, such as phenylephrine. Total surgical correction of the defect is performed under
cardiopulmonary bypass, and it can now be performed in young infants from 3-6 months of age or
earlier. Prognosis is good with total correction. However, the majority of them still have residual defects
and some of them may need reoperation and life long medical follow up.
Truncus arteriosus consists of a single arterial vessel arising from the heart, positioned over a
ventricular septal defect, supplying systemic, coronary and pulmonary circulations. It accounts for about
1%-4% of the congenital heart defects. Associated anomalies are common, such as DiGeorge syndrome.
Symptomatology depends upon the amount of pulmonary blood flow. With increased blood flow,
symptoms of congestive heart failure such as tachypnea, cyanosis, retractions, etc., develop. There may
be a systolic murmur at the left sternal border or an apical aortic ejection click. A diastolic murmur of
truncal insufficiency may be heard along the left sternal border. The electrocardiogram may show right or
left or combined ventricular hypertrophy. Chest x-ray shows an enlarged heart and increased pulmonary
vasculature. There may be a right aortic arch (25%). The echocardiogram shows a truncal root overriding
VSD, and pulmonary arteries arising from the trunk. Cardiac catheterization may be indicated when the
anatomic features are not clear on echocardiography. Management consists of treatment of congestive
heart failure followed by surgery. Surgical correction consists of closure of the VSD, separation of the
pulmonary arteries from the trunk and anastomosing them through a conduit from the right ventricle
(Rastelli procedure). The prognosis is poor in untreated cases. After surgery, they will need long term
follow up as they will eventually need to have the conduit graft replaced.
27
Cyanotic Congenital Heart Disease
Total anomalous pulmonary venous return (TAPVR) occurs in about 1%-2% of patients with congential
heart disease. There are four types of TAPVR causing left-to-right shunt: Supracardiac, cardiac,
infracardiac, and mixed. In the supracardiac type, pulmonary veins join to form a common vein which
drains into the SVC. In the cardiac type, the common pulmonary veins drain into the right atrium directly
or via the coronary sinus. In the infracardiac type, the common pulmonary vein courses downward
through the diaphragm into the portal vein, which then drains via hepatic veins into the inferior vena
cava.
Total Anomalous Pulmonary Venous Return
TAPVR and PAPVR
Must have ASD for survival
All have anatomical L to R shunt at atrial level
All have functional R to L shunt of oxygenated blood to right side of heart
Two Types
l Partial (PAPVR)
l Mild physiologic abnormality
l Usually asymptomatic
l Total (TAPVR)
l Serious physiologic abnormalities
Partial Anomalous Pulmonary Venous Drainage (PAPVR)
General
l One of the four pulmonary veins may drain into right atrium
l Mild or no physiologic consequence
l Associated with ASD
l Sinus venosus or ostium secundum types
Total Anomalous Pulmonary Venous Drainage (TAPVR)
l All have shunt through lungs to R side of heart
l All must also have R to L shunt for survival
l Obligatory ASD to return blood to the systemic side
l All are cyanotic
l Identical oxygenation in all four chambers
l Types
l Supracardiac
l Cardiac
l Infracardiac
l Mixed
l Supracardiac Type—Type I
l Most common (52%)
l Pulmonary veins drain into vertical vein (behind left pulmonary artery) to left brachiocephalic vein to
SVC
l DDx: VSD with large thymus
l Supracardiac Type 1—X-ray Findings
l Snowman heart = dilated SVC+ left vertical vein
l Shunt vasculature 2° increased return to right heart
28
Cyanotic Congenital Heart Disease
l Enlargement of right heart 2° volume overload
l Cardiac Type—Type II
l Second most common: 30%
l Drains into coronary sinus or RA
l Coronary sinus more common
l Increased pulmonary vasculature
l Overload of RV leads to CHF after birth
l 20% of I’s and II’s survive to adulthood
l Remainder expire in first year
l Infracardiac Type—Type III
l Percent of total: 12%
l Long pulmonary veins course down along esophagus
l Empty into IVC or portal vein (more common)
l Vein constricted by diaphragm as it passes through esophageal hiatus
l Severe CHF (90%) 2° obstruction to venous return
l Cyanotic 2° right to left shunt through ASD
l Associated with asplenia (80%), or polysplenia
l Prognosis = death within a few days
l Mixed Type—Type IV
l Percent of total: 6%
l Mixtures of types I – III
Anomalous pulmonary venous return could be total or partial. An atrial septal defect is necessary for
survival, since the oxygenated blood (from the pulmonary veins) must somehow reach the left side of the
heart. Symptomatology depends on the amount of mixing and whether or not the pulmonary veins are
obstructed. Cyanosis and signs and symptoms of congestive heart failure develop and progress rapidly.
There may be a grade 2/6 systolic ejection flow murmur heard along the left sternal border, or it may be
absent. The electrocardiogram shows right ventricular hypertrophy and right atrial hypertrophy. Chest xray shows increased pulmonary vascular markings or even edema, and the heart may be normal in size
or minimally enlarged.
The echocardiogram may show right ventricular volume overload, and a color-flow Doppler study may
help in locating the common pulmonary venous channel and its drainage. If the resolution is poor,
cardiac catheterization and angiocardiography may help in delineating the anomaly further. Treatment
consists of correction of the defect by surgery. If surgery is delayed and there is inadequate mixing,
palliative balloon septostomy may be performed. Prognosis is good after surgery. Prognosis is poor in
neonates with obstructive TAPVR. Long term follow up is needed to assess restenosis and late
arrhythmias.
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Cyanotic Congenital Heart Disease
Tricuspid atresia consists of an absence or atretic tricuspid valve and a hypoplastic right ventricle.
Blood from the right atrium enters the left atrium through an atrial septal defect or foramen ovale. They
may have associated lesions such as TGA, VSD, PDA, right aortic arch, pulmonic stenosis or atresia.
Communication between right and left circulation is essential to sustain life. Symptomatology depends
on the amount of pulmonary blood flow. In the absence of a VSD, as the PDA closes, patients may
develop intense cyanosis, tachypnea and tachycardia. The electrocardiogram usually shows left axis
deviation (very unlike the RVH seen in normal newborns) and right atrial hypertrophy and left-ventricular
hypertrophy. Chest x-ray may show increased or decreased pulmonary blood flow depending on the
shunt and a normal or mildly increased heart size. Echocardiography usually delineates these
abnormalities and very rarely a cardiac catheterization may be needed. Prostaglandin E1 may be life
saving in infants with low oxygen saturation with duct dependent pulmonary blood flow. This is followed by
a modified Blalock Taussig anastomosis. If the interatrial communication is narrow (small PFO/ASD) then
a balloon or blade atrial septostomy is performed. Surgical correction initially consists of a bilateral Glenn
procedure (superior vena cava to right pulmonary artery shunt) followed by an inferior vena cava
anastomosis to the right pulmonary artery through an intra or extra cardiac baffle (modified Fontan
procedure). Prognosis is good after surgery but patients will need multiple surgeries with associated
morbidity such as pleural effusion, ascites, arrhythmia and mortality.
Ebstein anomaly is characterized by downward displacement of the septal and posterior leaflets of the
tricuspid valve which are attached to the right ventricular septum. The anterior leaflet is elongated and is
displaced downward within the right ventricular cavity causing "atrialization of the right ventricle" (i.e., the
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Cyanotic
Congenital Heart Disease
displaced downward within the right ventricular cavity causing "atrialization of the right ventricle" (i.e., the
right ventricle is small).
There is usually a PFO or an ASD or PS (pulmonic stenosis). Cyanosis depends up on the right to left
shunt. Auscultation may reveal a triple or quadruple gallop rhythm and a split second heart sound. A
pansystolic murmur of tricuspid insufficiency or an ejection murmur of PS may be heard. The
electrocardiogram shows a right bundle branch block pattern, giant P waves and sometimes first degree
AV block or WPW syndrome (delta wave). Chest x-ray shows a huge right atrium and gross cardiomegaly.
Echocardiography reveals the lesions of Ebstein anomaly and only rarely is cardiac catheterization
needed. Treatment is mainly palliative and there are no good surgical options. In older patients, tricuspid
annuloplasty and rarely tricuspid valve replacement may be performed. Prognosis depends on the
severity of the lesion. Prognosis is good with mild lesions and poor with severe lesions with other
associated anomalies/malformations.
Hypoplastic left heart syndrome consists of a combination of mitral stenosis or atresia, severe aortic
stenosis or atresia, and a small left ventricle. Systemic circulation depends on the patency of the ductus.
These infants may appear reasonably well at birth until either the pulmonary vascular resistance drops or
the PDA closes. They then present with shock, variable cyanosis, poor pulses, poor perfusion and CHF. A
systolic murmur may or may not be present. Chest x-ray shows increase vascularity and EKG may show
RV hypertrophy. Echocardiography is diagnostic. Early management consists of administration of PGE1
and treatment of CHF. Surgery consists the Norwood surgical procedure and a few centers perform
cardiac transplantation for this lesion. Prognosis is guarded.
Questions
1. A two day old cyanotic infant with a grade 3/6 ejection systolic murmur is noted to have decreased
pulmonary vascular markings on chest x-ray and left axis deviation on EKG. The most likely diagnosis is:
a. Tetralogy of Fallot
b. Transposition of Great Vessels
c. Truncus Arteriosus
d. Tricuspid Atresia
2. A 2 year old infant is noted to have mild cyanosis who assumes a squatting position during long
walking. He is noted to have increasing fussiness followed by increasing cyanosis, limpness and
unresponsiveness. The most likely underlying lesion is:
a. Hypoplastic left heart
b. Transposition of the Great Vessels
c. Anomalous Pulmonary Venous Return
d. Tetralogy of Fallot
e. Aspiration with obstruction to air passages
3 . An infant with a marked cyanotic congenital heart defect with decreased pulmonary vascularity
should be treated with:
a. Digoxin
b. Indomethacin
c. Prostaglandin E1
d. Epinephrine
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Cyanotic Congenital Heart Disease
1.
2.
3.
4.
5.
4. Cyanosis is produced by the presence of deoxygenated hemoglobin of at least:
a. 1-2 gm/dL
b. 3-5 gm/dL
c. 6-8 gm/dL
d. 9-10 gm/dL
5. A "tet spell" or "blue" spell of tetralogy of Fallot is treated with all of the following except:
a. oxygen
b. knee chest position
c. morphine
d. digoxin
e. propranolol
f. phenylephrine
g. sodium bicarbonate
6. Pulmonary vascularity is increased in all of the following except:
a. TAPVR
b. Tricuspid atresia
c. TGV
d. Hypoplastic left heart
7. Pulmonary vascularity is decreased in all of the following except:
a. Tetralogy of Fallot
b. Pulmonary atresia
c. TAPVR
d. Tricuspid atresia
Answers to questions
1.d, 2.d, 3.c, 4.b, 5.d, 6.b, 7.c
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