Download PATHOPHYSIOLOGY OF CONGENITAL HEART DISEASE

PATHOPHYSIOLOGY OF CONGENITAL HEART DISEASE
OBJECTIVES:
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At the end of the lecture students will be able to
understand and describe the Pathophysiology of:
Congenital heart defects
Acyanotic heart diseases
Cyanotic heart diseases
Left to right shunts
Right to left shunts
CONGENITAL HEART
DEFECTS
 Faulty embryogenesis (week 3-8)þ
 Usually MONO-morphic (i.e., SINGLE lesion) (ASD, VSD, hypoRV, hypo-LV)
 May not be evident until adult life (Coarctation, ASD)
 Overall incidence 1% of USA births
 INCREASED simple early detection via non invasive methods,
e.g., US, MRI, CT, etc.
Incidence per Million Live
Births
%
4482
42
Atrial septal defect
Pulmonary stenosis
1043
10
836
8
Patent ductus arteriosus
781
7
Tetralogy of Fallot
577
5
Coarctation of aorta
492
5
Atrioventricular septal defect
Aortic stenosis
396
4
388
4
Transposition of great arteries
Truncus arteriosus
Total anomalous pulmonary venous connection
Tricuspid atresia
388
4
136
1
120
1
MALFORMATION
Ventricular septal defect
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GENETICS
Gene abnormalities in only 10% of CHD
Trisomies 21, 13, 15, 18, XO
Mutations of genes which encode for transcription
factorsTBX5ASD,VSD
 NKX2.5ASD
Region of chromosome 22 important in heart development,
22q11.2 deletionconotruncus, branchial arch, face
ENVIRONMENT
 RUBELLA
 TERATOGENS
CONGENITAL HEART DISEASE
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Congenital heart disease is often divided
into two types:
Cyanotic (blue discoloration caused by a relative lack of oxygen)
non-cyanotic
LR SHUNTS: all “D’s” in their names
NO cyanosis
Pulmonary hypertension
SIGNIFICANT pulmonary hypertension is IRREVERSIBLE
RL SHUNTS: all “T’s” in their names
CYANOSIS (i,.e., “blue” babies)
VENOUS EMBOLI become SYSTEMIC
OBSTRUCTIONS
LR
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ASD
VSD
ASVD
PDA
CONGENITAL HEART DISEASE
 Non-cyanotic: (left to right shunt)
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Ventricular septal defect (VSD)
Atrial septal defect (ASD)
Patent ductus arteriosus (PDA)
Aortic stenosis
Pulmonic stenosis
Coarctation of aorta
Atrioventricular canal (endocardial cushion defect)
ASD
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NOT patent foramen ovale
Usually asymptomatic until adulthood
SECUNDUM (90%): Defective fossa ovalis
PRIMUM (5%): Next to AV valves, mitral cleft
SINUS VENOSUS (5%): Next to SVC with anomalous pulmonary
veins draining to SVC or RA
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Sinus venosus defect: high in the septum.
Ostium secundum defect: midseptum.
Ostium primum defect: low in the septum.
Pathophysiology: L-R shunt-increased flow across Rt heart-RV
& PA enlargement.
 Clinical features: asymptomatic, slow wt gain,
 Diagnosis: Rt ventricular heave, systolic murmur, fixed wide
split S2.
ATRIAL SEPTAL DEFECT
ATRIAL SEPTAL DEFECT
VSD
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By far, most common CHD defect
Only 30% are isolated
Often with TETRALOGY of FALLOT
90% involve the membranous septum
If muscular septum is involved, likely to have multiple holes
SMALL ones often close spontaneously
LARGE ones progress to pulmonary hypertension.
 VENTRICULAR SEPTAL DEFECT
 Most common CHD (26%),may be single or
 multiple
 Pathophysiology: Lt-Rt shunt as long as pulmonary vascular
resistance is lower than systemic resistance, if reverse shunt
reverses
 Large defects lead to pul. hypertension-Eissenmenger
syndrome.
 Clinical features: depend on size, asymptomatic, growth failure,
recurrent LRTI, congestive heart failure,
 Diagnosis: pansystolic murmur,
 Asymptomatic if defect is small.
 Heart failure with dyspnea, frequent respiratory infections, and
poor growth if defect is large.
 Pansystolic murmur maximal at the left sternal border.
PDA
 90% isolated
 HARSH, machinery-like murmur
 LR, possibly RL as pulmonary hypertension approaches
systemic pressure
 Closing the defect may be life saving
 Keeping it open may be life saving (Prostaglandin E1). Why?
Ans: TGA, TA, TAPVC
 Connection between PA & descending aorta
 10% of CHD
 Pathophysiology: Lt-Rt shunt, reverses if pulmonary resistance
increases-RV enlargement. If PDA is large Eissenmenger
syndrome can develop
 Clinical features: depend on size & direction of flow, slow
growth
 Diagnosis: bounding pulse, continous murmur, loud S2
 Murmur usually systolic, sometimes continuous, “machinery”
 Poor feeding, respiratory distress, and frequent respiratory
infections in infants with heart failure
 Physical exam and echocardiography
AVSD
 Associated with defective, inadequate AV valves
 Can be partial, or COMPLETE (ALL 4 CHAMBERS FREELY
COMMUNICATE)þ
 COMPLETE ATRIOVENTRICULAR CANAL
RL
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Tetralogy of Fallot
Transposition of great arteries
Truncus arteriosus
Total anomalous pulmonary venous connection
Tricuspid atresia
CONGENITAL HEART DISEASE
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Cyanotic: (right to left shunt)
Tetralogy of Fallot
Transposition of the great vessels
Tricuspid atresia
Total anomolous pulmonary venous return
Truncus arteriosus
Hypoplastic left heart
Pulmonary atresia
Some forms of total anomalous pulmonary venous return
Ebstein’s anomaly
RL SHUNTS
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TETRALOGY of FALLOT most COMMON
1) VSD, large
2) OBSTRUCTION to RV flow
3) Aorta OVERRIDES the VSD
4) RVH
SURVIVAL DEPENDS on SEVERITY of SUBPULMONIC
STENOSIS
 Can be a “PINK”
tetrology if pulmonic obstruction is small, but
the greater the obstruction, the greater is the RL shunt
TETRALOGY OF FALLOT
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Pulmonary stenosis
VSD of the membranous portion
Overriding aorta
Right ventricular hypertrophy due to shunting of blood
Addition of an atrial septal defect falls in the category of
Pentalogy of Fallot.
 Hypoxic spells and squatting.
 Cyanosis and clubbing.
 Addition of an atrial septal defect falls in the category of
Pentalogy of Fallot.
 Hypoxic spells and squatting.
 Cyanosis and clubbing.
TGA (TRANSPOSITION
of GREAT ARTERIES)
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NEEDS a SHUNT for survival, obviously
PDA or PFO (65%), “unstable” shunt
VSD (35%), “stable” shunt
RV>LV in thickness
Fatal in first few months
Surgical “switching”
Aorta from right ventricle, pulmonary artery from left ventricle
Cyanosis from birth, hypoxic spells sometimes present
Heart failure often present
Cardiac enlargement and diminished pulmonary artery segment
on x-ray
 Anatomic communication must exist between pulmonary and
systemic circulation, VSD, ASD, or PDA.
 TRUNCUS ARTERIOSUS
 Single large vessel overrides the ventricular septum and
distributes all the blood ejected from the heart.
 Large VSD is present.
TRICUSPID ATRESIA
 Tricuspid valve is completely absent in about 2% of newborns
with congenital heart disease.
 Blood flows from right atrium to left atrium through foramen
ovale.
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Early cyanosis.
Hypoplastic RV
Needs a shunt,
ASD, VSD, or PDA
High mortality.
 Total Anomalous Pulmonary Venous Connection (TAPVC)
 PULMONARY VEINS do NOT go into LA, but into L. innominate
v. or coronary sinus
 Needs a PFO or a VSD
 HYPOPLASTIC LA
 Pulmonary veins do not make a direct connection with the left
atrium.
 Blood reaches the left atrium only through an atrial septal defect
or patent foramen ovale.
 Pulmonary congestion, tachypnea, cardiac failure, and variable
cyanosis.
OBSTRUCTIVE CHD
 COARCTATION of aorta
 Pulmonary stenosis/atresia
 Aortic stenosis/atresia
PULMONARY STENOSIS
 No symptoms in mild or moderately severe lesions.
 Cyanosis and right-sided heart failure in patients with severe
lesions.
 High pitched systolic ejection murmur maximal in second left
interspace.
 Ejection click often present.
COARCTATION OF AORTA
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M>F
But XO’s frequently have it
INFANTILE FORM (proximal to PDA) (SERIOUS)
ADULT FORM (CLOSED DUCTUS, i.e., NO PDA)
Bicuspid aortic valve 50% of the time
AORTIC STENOSIS/ATRESIA
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VALVULAR
If severe, hypoplastic LVfatal
SUB-valvular (subaortic)þ
Aortic wall THICK BELOW cusps
SUPRA-valvular
Aortic wall THICK ABOVE cusps in
ascending aorta
 Asymmetric Septal Hypertrophy
(Idiopathic
 Hypertrophic Subaortic Stenosis)