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Fetal circulation
EMBRYONIC
PERIOD:
Placenta serves as the exchange
organ
for
respiration
and
metabolismus. Oxygenated blood
(80%) passes from the placenta
through the umbilical vein to the
heart. As the flows toward the heart,
it mixes with blood from the inferior
vena cava and from hepatic veins, so
that blood entering the right atrium is
approximately 65% saturated. A
considerable amount of this blood is
shunted across the foramen ovale
into the left atrium. The venous blood
from upper part is much less
saturated - 30% and most of it enters
the right ventricule through tricuspid
valve. Thus, the blood in right
ventricle is a mixture of both
relatively highly saturated blood from
the umbilical vein and desaturated
blood from venae cavae. This mixture
result in saturation 50% in the right
ventricle.
The blood in the left atrium is
derived from the blood shunting
across the foramen ovale and the
blood returning from pulmonary
veins. Saturation is 60%. A great deal
of the left ventricular output goes to
the head, the lower portion of the
body is supplied by blood both from
right ventricle, through the patent
ductus arterious, and from the left
ventricle.
- till 8 weeks of
gestation
- foundation of all
organs - all have
developed
- the most
vulnerable by
exogenic
influences viral, chemical,
physical ...
FETAL PERIOD:
- since week 9th of
gestation till birth
- growth
- remodeling
- functional development
Transient neonatal circulation
Basic Principles
Cardiovascular diseases are a significant cause of
death and chronic illness in pediatric population.
Frequency, incidency: about 1% of newborns have
congenital heart disease.
Note ! The most important clues to the presence of
heart disease requiring prompt attention, diagnosis
and managment is congestive heart failure and/or
cyanosis.
(Cyanosis = more than 5g of reduced Hb/l)
The cardiologist and neotologist use for this situation
a therm: „critical heart disease“.
The presence of a heart murmur is not a significant
sign of heart disease. The murmur may suggest the
possibility of heart disease in an infant, or the
murmur can be a functional or innocent murmur. On
ohter hand not all serious heart diseases are
accompanied by a murmur.
Etiology of Congenital Heart Defects
With incidence about 1% the CHD are the most
common structural malformation.
- cca 8% of all CHD are know to be associated with
gene or chromosome abnormalities - M.Down, Turner
syndrome, DiGeorge syndrome.
- multiple enviromental factors: diabetes mellitus,
alcohol consumption, progesteron use, and other
teratogenes.
- congenital - embryo and fetus infections, certain
viruses. Typicall example is rubella syndrom (Gregg
syndrom - CHD, pulmonary stenosis + cataracta,
microphtalmia + deafness, hearing loss)
In dealing with families of children with CHD the
physician must often answer the question of risk for
feature pregnancies. For siblings is cca 2-5%. More
higher is the risk for child of affected mother - 1015%.
The division of CHD: (and incidence, % of all CHD)
a) with left-right shunt - NONCYANOTIC
- ventricular septal defect 20%
- patent ductus arteriosus 12%
- atrial septal defect 10%
- atrioventricular septal defect - AV canal 4%
The division of CHD: (and incidence, % of all CHD)
b) with right-left shunt - CYANOTIC
- tetralogy of Fallot 10-15%
- complete transposition of the great arteries 10-12%
- pulmonary atresia 3 %
- tricuspid atresia 1%
- hypoplastic left heart 1%
- persistent truncus arteriosus 1%
- origin of both great vessels from the right ventricule
rare
- total anomalous pulmonary venous return rare
The division of CHD: (and incidence, % of all CHD)
c) without shunt
1) Malformations associated with obstruction to blood flow on
the right side of the heart:
- valvular pulmonary stenosis with intact vent. septum 10%
- infundibular pulmonary stenosis with intact v.s.
- distal pulmonary stenosis
2) Malformations associated with obstruction to blood flow on
the left side of the heart:
- coarctation of the aorta 6%
- aortic stenosis 0.2%
- mitral valve prolaps rare
- congenital mitral stenosis rare
- cor triatriatum extrem rare
- Ebstein´s malformation of the tricuspid valve rare
- congenital mitral regurgitation rare
- congenital aortic regurgitation - bicuspidal aortic valve
3) Congenital myocardial diseases: all are very rare
- glycogen storage disease - glykogenosis type II. Pompe
- anomalous origin of the left coronary artery
- endocardial fibroelastosis
LR shunt
Ventricular septal defect:
VSD
most common CHD - 25%
Essential for dg.: - signs depandent on the size of the defect
- „ hemodynamic significance“
LR shunt
VSD
Clinic: depands on size of the defect. History of frequent
respiratory infections, pansystolic murmur, children are early
sick in infancy. Failure to thrive. Dyspnea, exercise intolerance.
Congestive heart failure may develop between 1-6 months of
age.
Danger: In hemodynamic significant defect can develop
pulmonary hypertension and the shunt can revert to rightleft with cyanosis = Eisenmenger syndrome.
a. Pharmac. treatment: When signs of congestive heart failure treatment this (Digoxin, Furosemid).
b. Surgical treatment: patch
1) 30-50% of all ventricular septal defects close spontaneously
and half of the defects that not close become functionally and
anatomically smaller. So asymptomatic patients with hearts
normal size and without pulmonary hypertension are not
indicated for surgical patch.
2) Patients with the ratio of pulmonary to systemic blood flow
more than 2:1 or with congestive heart failure and without
pulmonary hypertension are indicated for surgical repair in age
2-5 years.
3) In age less than 2 years, when pulmonary hypertension is
begining to develop (before reaching of inoperable levels !!!) is
surgical repair - patch indicated or in centers which are not
capability of doing total correction a palliative procedure pulmonary artery bandage.
LR shunt
Patent ductus arteriosus:
Essential of diagnosis: - variable murmur with active
precordium and full pulses in newborns
- continuous murmur and full pulses in older infants.
DAP
LR shunt
DAP
PDA is the persistence of the normal fetal vessel that joint
pulmonary arteria to the descendet aorta. It closes normally
during first 4 days of life. Very common problem in intensive
care premature nurseries. The frequency in newborns
weighing less than 1500 g is to 60%.
Clinics: The pulses are bounding and pulse pressure is
widened (Psys-Pdia > 1/2 of Psys). Very rough „machinery“
continuous murmur at the 2.intercostal space left, inferioir the
clavicule. If the shunt is large, congestive heart failure
becomes important.
Danger: pulmonary hypertension, subacuta bacterial
endocarditis, congestive heart failure.
Treatment: Surgical ligature or resection of ductus.
Premature newborns are a specific problem. Ligature is rarely
done. The pharmacology closure be using of indomethacin
the most frequent intervation.
Atrial septal defect of the ostium secundum:
10% CHD
Essential for dg.: - visualisation of defect by Echo
- S2 widely split and fixed
- ejection systolic murmur 1-3/6 at the left sternal border pulmonary area, widely radiating - can mimick peripheral
pulmonary artery stenosis
- diastolic flow murmur at lower left sternal border if shunt is
significant in size
- ECG with rsR´ in lead V1, right axis deviation.
LR shunt
ASD
LR shunt
ASD
Clinic: Children with this defect often have no
problems. Some patient remain asymptomatic
throughtout life, but others can failure to thrive and
may be with congestive heart failure and pulmonary
hypertension late in life, typically in third decade.
When pulmonary hypertension develops the
previously left-right shunt revers to right-left shunt and
cyanosis appears.
Treatment: Surgical closure (patch) is recommended
when the ratio of pulmonary to systemic blood flow is
greater than 2:1. Operation is performed in age 2-4
years. Early operation is indicated in infants presenting
with congestive heart failure and/or pulmonary
hypertension.
LR shunt
AVC
Atrioventricular septal defect - AV canal:
Essential of diagnosis: - murmur often inaudible in
neonates, - loud pulmonary component of S2
- common in infants with Down´s syndrome
- ECG with left axis deviation, first-degree heart
block in 50% of cases, R, L or combined ventricular
hypertrophy
High ventricular septal defect, low atrium septal defect
of ostium primum and cleft of both valves - septal leaflet of the
tricuspid and the arterior leaflet of the mitral valve.
Marked left to right shunt at atrial and
ventricular levels and regurgitation of both valves.
Marked pulmonary hypertension. Incomplete forms are . possible.
Clinics: Incomplete form may be indistinguishable from
atrial septal defect type ostium secundum. On other
hand infants with complete form are severe sick with
recurent pneumonia and early congestive heart failure.
Treatment: complete anatomic correction as soon as possible
RL shunt
Tetralogy of Fallot:
1.Ventricular septal defect + 2.Severe infundibular pulm.
stenosis - obstruction to right ventricular outflow +
3.Overriding of the aorta (dextroposition) + 4.Right ventricul.
hypertrophy ... + other: right sided aortic arch (25%), atrial
septal defect (15%)
Essential of diagnosis: - cyanosis after the neonatal peridod,
- hypoxemic spells during infancy, - systolic ejection murmur
at upper left sternal border
TOF
RL shunt
TOF
RL shunt
TOF
Clinics: The degree of R-L shunt and cyanosis is dependent
upon the degree of right ventricular outflow obstruction.
Failure to thrive. Clubbing of fingers. Quite all children with
cyanosis have a mikrocytic, hypochromic polyglobulia with
very high hematocrit.
Hypoxemic spells: are characteristic signs for Fallot tetralogy.:
- 1.sudden onset of cyanosis or deeping of preexisting
cyanosis + 2. sudden onset of dyspnea + 3.alteration of
consciousness (syncope) + 4.decrease in intesity of murmur.
Treatment: Oxygen and placing in knee-chest position +
propanolol i.v. - NO Digoxin.
Treatment: Total surgical correction as soon as possible.
Paliative op „Blalock-Taussig shunt“.
RL shunt
TGA
Complete transposition of the great arteries:
Essential of diagnosis:-cyan.newborn-more common in males.
The aorta is located anterior to the pulmonary artery and is
outgoing from right ventricule, pulmonary artery from left. In
most cases associated intracardiac abnormalities are present:
v. and a. septal def., pulm. stenosis, patent ductus. Life is
possible thanks a shunt via one of these defects.
RL shunt
TGA
Clinics: Deep cyanosis in newborns age. Without emergency
treatment can only occasionaly live - cyanosis progress most
severe, failure to thrive. Murmurs are not characteristic,
dependent on associated defects.
Treatment: First help: Continual infusion with prostaglandin
E2 to decrease pulmonary hypertension and achieve opened
ductus arteriousus.
In newborns cathetrization with Rashkind baloon
atrioseptostomy - to shunting at atria level.
Previously was a paliative operation done - an insertion of an
intra-atrial baffle to redirect systemic and pulmonary blood
flow to the appropriate artery (Op Mustard, Senning). Now is
an anatomic correction - switch of great artery avaible.
RL shunt
PA
Pulmonary atresia:
1) With ventricular septal defect: it is an extreme form of Fallot
tetralogy, the pulmonary blood flow is derived via patent
ductus arteriousus from aorta. Suddenly death may occurs
with postnatal closure of ductus. Treatment is an urgent
systemic - pulmonary anastomosis (Blalock-Taussig).
2) With intact ventricular septum:
Essential of diagnosis: - cyanosis at birth, - continuous
murmur (PDA), - x-ray with concave pulmonary artery and apex
tilted upward.
Patient´s life depends upon patency of the ductus.
Clinic: Severe cyanosis, severe dyspnea. Patient can died
suddenly with ductus closure.
Treatment: First: maintaining patency of ductus by use of
prostaglandin E2. Paliative intervation to achieve the mixing
of blood at level of atrias - Rashking baloon atrioseptostomy
during cathetrization and paliative shunt.
Anatomic correction - definitive reconstruction of the right
ventricular outflow tract is in some cases possible at a later
age.
RL shunt
Tricuspid atresia:
Hemodynamic is very complex, depends upon concomitant
defects: transposition of the great artery, ventricular septal
defect, patent ductus arterious, pulmonary stenosis or
atresia, hypoplastic pulmonary arteria. Atrial septum
defect is life saving.
Essential of diagnosis: - marked cyanosis present from
birth, - ECG with left axis deviation, right atrial enlargment
and left ventricular hypertrophy.
Clinic: Because there is no direct communication between
the right atrium and right ventricule, the systemic venous
return must flow through the atrial septum defect. Filling
of the right ventricle depends upon ventricular septal
defect. Complete mixing of blood and the degree of the
cyanosis - arterial desaturation depends upon other defects
/ transposition, PDA, pulmonary hypoplasia.
Treatment: Fontan procedure - connection of right atrium to
right ventricule or pulmonary artery (without valve).
TA
RL shunt
Hypoplastic left heart syndrome:
is present by mitral and aortic atresia. Prognosis poor.
During the past years a palliative surgical approach is
done with the aim of heart transplantation in the later
age.
RL shunt
Total anomalous pulmonary venous return:
Essential of diagnosis: - mild cyanosis, - systolic ejection
murmur with left sternal border, - right atrial and right
ventricular hypertrophy.
The pulmonary venous blood does not drain into left atrium
but entry into right atrium or into vena cava or portal vena.
A right - left shunt is always present at the atrial level via a
defect of the septum.
Clinic: Complete mixing of venous and arterial blood.
Patients are relatively good when the pulmonary resistance
and flow are good. In case of increased pulmonary
resistance and hypertension the patients are being worst
and the cyanosis markedly and develop severe right heart
failure. Frequent respiratory infects. Failure to thrive.
Treatment: Rashkind. Surgical anatomic correction is
possible in some cases.
RL shunt
without shunt
Malformations associated with obstruction to blood flow
on the right side of the heart:
Valvular pulmonary stenosis with intact
vent.septum:
Essential of diagnosis: - NO SYMPTOMS with mild and
moderately severe cases, - righ-sided congestive heart
failure in very severe cases, - systolic ejection murmur,
- widely split S2, - right ventricular lift, - dilated
pulmonary artery „poststenotic“.
Clinic: Cyanosis only in very severe cases - right-left
shunt at the atrail level via a septal defect. Patients with
a mild or moderate degree of valvular pulmonary
stenosis are asymptomatic during childhood. On other
hand severe stenosis may produce cyanosis and
congestive right heart failure even in neonatal period.
Treatment: Balloon valvuloplasty via cathetrization.
Surgical valvotomy is possible too.
Malformations associated with obstruction to blood flow
on the left side of the heart:
Coarctation of the aorta:
occurs in thoracic portion of the descending aorta., usually
in the juxtaductal portion, rather then pre- or postductal
postition. Males 3times affected.
Essential of diagnosis: - pulse lag in lower extremities, blood pressure of 20 mm Hg greater in upper than in lower
extremities, - systolic murmur in the left axilla.
without shunt
without shunt
Coarctation of aorta syndrome: + patent ductus,
hypoplasia of aorta isthmus, ventricular septal defect and
bicuspid aorta valve.
Clinic: Is depended on the hemodynamic significance,
mass of the stenosis. Patients may not have symptoms
during whole childhood, or only a decreased exercise
tolerance and fatigability. In severe cases may congestive
left heart failure develop. The most important physical
finding is a diminution or abscence of femoral pulses. The
pathognomic murmur of coarctation is heard in the
interscapular area of the back.
Treatment: Resection of the coarctation and end to end
anastomosis at the optimal age - as late as possible.
Anticongestive measure when left sided congestive heart
failure is present. In cases of systemic hypertension systemic resistance decreasing by using of nitroprussid,
betablocators - propranolol, trimepranol ...
Percutaneous baloon angioplasty is avaible.
without shunt
Aortic stenosis:
is an obstruction to the outflow from the left ventricule at or
near the aortic valve: - valvular (75%), - discrete membranous
subvalvular (20%), - supravalvular, - idiopathic hypertrophic
subaortic stenosis.
Essential of diagnosis: - systolic ejection murmur at upper
right sternal border, - thrill in carotid arteries, - systolic clic at
the apex, - dilatation of the ascending aorta on chest X-ray, left ventricular hypertrophy on ECG
Clinic: Most patients may be asymptomatic until the
congestive left heart failure develop in the third-fifth decade of
life. Although some patients have exercise intolerance and
fatigability. Syncope and sudden death are uncommon but
possible.
Treatment: Surgical repair should be considered only in
patient with great gradient (80 mmHg) across the stenosis.
Percutanous baloon valvuloplasty is the first choice.
without shunt
without shunt
Mitral valve prolaps:
Essential of diagnosis: - midsystolic click best heard with
patient in standing position, - late systolic murmur.
Clinic: Asymptomatic. Chest pain, palpitation.
It is a benign entity.
Treatment: No. Betablocators may be usefull in chest pain.
Rarely may be complicated by mitral insuficiency.
without shunt
Ebstein´s malformation of the tricuspid valve:
consist of downward displacement of the tricuspid valve
such that the greater portion of the valve is attached to the
ventricular wall. The upper portion of right ventricule is in
the right atrium. Functionally small capacity of right
ventricule.
Prophylactic Regimens for Dental, Oral, Respiratory Tract, or Esophageal
Procedures. (Follow-up dose no longer recommended.) Total children's dose
should not exceed adult dose.
Standard general prophylaxis for patients at risk:
Amoxicillin: Adults, 2.0 g (children, 50 mg/kg) given orally one hour before
procedure.
Unable to take oral medications:
Ampicillin: Adults, 2.0 g (children 50 mg/kg) given IM or IV within 30 minutes
before procedure.
Prophylactic Regimens for Genitourinary/Gastrointestinal Procedures:
High-risk patients:
Ampicillin plus gentamicin: Ampicillin (adults, 2.0 g; children
50 mg/kg) plus gentamicin 1.5 mg/kg (for both adults and
children, not to exceed 120 mg) IM or IV within 30 minutes
before starting procedure. 6 hours later, ampicillin (adults, 1.0
g; children, 25 mg/kg) IM or IV, or amoxicillin (adults, 1.0 g;
children, 25 mg/kg) orally.