Week 4: congenital heart disease

Question 1

Describe the classification of congenital heart defects

Answer 1

1. Acyanotic (shunt) lesions: atrial septal defect, ventricular septal defect, patent ductus arteriosus
2. Obstructive lesion: pulmonic stenosis, aortic stenosis, coarctation of the aorta
3. Cyanotic lesions: transposition of the great arteries, tetralogy of fallot, tricuspid atresia, total anomalous pulmonary venous return, truncus arterioles, pulmonary atresia

Question 2

Describe atrial septal defect.

Answer 2

• left to right shunt: RV compliance greater than LV compliance, leads to right heart volume overload
• symptoms: prominent RV impulse, systolic ejection murmur (pulmonic), split 2nd heart sound.
• increased work of RV, can dilate and hypertrophy, b/c pulmonary return can go from LA to RA to RV back to pulmonary circulation.
• 6-10% of CHD, may be asymptomatic or close spontaneously for small detects
• late risks: paradoxic embolism, arrhythmias

Question 3

Describe 2 types of ventricular septal defect.

Answer 3

1. pressure restrictive
   - small defect and can maintain pressure differential for a long time
2. non-restrictive
   - large defect, pressure in RV and LV equalize, 5x as much circulation to lungs than to body

Question 4

Descrive the physiology of VSD.

Answer 4

• based on size of defect
• harsh systolic murmur in small VSD -pressure restrictive
• in large VSD: LV=RV pressure, and have L to right shunt, leading to LV volume overload, CHF and diastolic murmur
• pulmonary HTN: LV=RV pressure and PVR>SVR, right to left shunt, get cyanosis, Loud p2, decreased shunt volume

Question 5

Describe patent ductus arteriosus.

Answer 5

• failure of DA to close at birth, common in premature infants
• normal closure due to increased O2 pressure in arteries, and decrease in prostaglandins
• shunt volume: depends on diameter of PDA, SVR and PVR,
• normal closure is normally in first 24 hrs
• get a circulatory continuous heart murmur because continuous pressure gradient in systole and diastole: aortic is greater than pulmonary pressure, so blood goes from aorta to pulmonary artery
• Rx: surgery ligation in infant, coil/device embolization in child
• risks of CHF, resp failure in newborn, and endocarditis in child

Question 6

Describe pulmonary valve stenosis.

Answer 6

• pressure in RV has to increase, leading to hypertrophy and hyperplasia of RV (up till 1st year of life, can have myocyte proliferation)
• PA dilates
• harsh systolic murmur and ejection click
• rx: balloon catheter dilation

Question 7

Describe aortic stenosis in congenital heart defects.

Answer 7

• dysplasia/fusion of aortic leaflets limits motion
• obstruction to LV systolic ejection leads to LVH
• harsh murmur, ejection click, suprasternal thrill
• rx: balloon catheter dilation/surgery

Question 8

Describe hypoplastic left heart syndrome.

Answer 8

• left heart is underdeveloped and ascending aorta doesn’t develop since LV doesn’t pump blood into it
• Rx: norwood procedure, ascending aorta is connected to the right ventricle, then a shunt connection from another artery such as the subclavian to pulmonary artery to send blood to the lungs.

Question 9

Describe coarctation of the aorta.

Answer 9

• narrowing of aorta, there’s a pressure gradient between ascending and descending aorta.
• in newborn coarctation: differential cyanosis: upper body has aortic flow, lower body has PDA flow
• in post-neonatal: blood pressure gradient where arms> legs, upper extremity HTN and collateral arterial flow
• Rx: in severe obstruction in neonates, prostaglandin infusion to keep DA patent to maintain blood flow to descending aorta before surgery.

Question 10

Describe tetralogy of Fallot

Answer 10

-there’s unequal division of RV/LV outflow tracts, aorta lies partly over right ventricle. Less blood is going to pulmonary artery. Deoxygenated blood may move across VSD to aorta, will have cyanosis.
FEATURES
1. VSD
2. Pulmonary stenosis
3. RVH
4. Overriding aorta
CLINICAL
-harsh systolic murmur due to PS
-decreased pulm. markings on CXR, boot shaped heart on CXR
-Rx: surgical, patch to close VSD, and patch to enlarge PA

Question 11

Describe transposition of the great arteries.

Answer 11

-pulmonary artery over LV and aorta over RV. Circulation of oxygenated blood in lungs and of blue blood in systemic circulation.
-usually PDA remains patent so that there is some oxygenated blood to body, only viable for a few days.
-due to failure of AP septum to rotate
CLINICAL
-cyanosis at birth
-murmur not always present
-increased pulm. markings on CXR
-Rx: balloon atrial septosotomy to allow mixing, surgical switch with coronary translocation.