6. Congenital Heart Diseases

Question 1

Definition of congenital heart diseases

Answer 1

Abnormalities of the heart or great vessels that are present from birth

Question 2

Types of congenital heart diseases

Answer 2

1. Left-to-right shunt
   a. Atrial septal defect
   b. Ventricular septal defect
   c. Patent ductus arteriosus
2. Right-to-left shunt
   a. Tetralogy of Fallot
   b. Transposition of the great vessels
   c. Tricuspid atresia
   d. Persistent truncus arteriosus
3. Obstructive congenital anomalies
   a. Coarctation of aorta
   b. Pulmonary stenosis & atresia
   c. Aortic stenosis & atresia

Question 3

Definition of Left-to-Right Shunts

Answer 3

Typically acyanotic at onset, but may become cyanotic with eventual pulmonary hypertension or shunt reversal

Question 4

Atrial septal defect

Answer 4

1. Abnormal, fixed opening in the atrial septum due to
   incomplete tissue formation
2. Despite right sided volume overload, ASD is usually well totally and asymptomatic until adulthood
3. Ejection systolic murmur (due to excessive flow through the pulmonary valve) + permanent splitting of S2

Question 5

Ventricular septal defect

Answer 5

1. Incomplete closure of the ventricular septum (mostly in the membranous portion, minority in the muscular part)
2. Functional consequences depend on size of VSD
   - If small, asymptomatic until adulthood
   - If large, cause right ventricular hypertrophy &
   pulmonary hypertension virtually from birth, which may progress to irreversible pulmonary vascular disease and shunt reversal (Eisenmenger syndrome)
3. Pan-systolic murmur

Question 6

Patent ductus arteriosus

Answer 6

1. Ductus arteriosus remaining open after birth
2. Depending on diameter of PDA, may result in progressive
   obstructive changes in pulmonary vasculature (due to
   pulmonary volume overload)
3. Continuous/harsh/machinery-like murmur

Question 7

Definition of right-to-left shunts

Answer 7

Typically cyanotic

Question 8

Tetralogy of fallot

Answer 8

1. Four cardinal features that arises from an anterocephalad deviation of the anterior septum:
   - Ventricular septal defect
   - Aorta that overrides the VSD
   - Pulmonary stenosis
   - Right ventricular hypertrophy

PROVe - Pulmonary stenosis, Right ventricular hypertrophy, Overriding aorta, VSD

2. Heart is enlarged & ‘boot-shaped’

Question 9

Transposition of the great vessels

Answer 9

1. Ventriculoarterial discordance: aorta originates from RV, pulmonary trunk from LV
2. Due to abnormal formation of truncal septa
3. Right ventricular hypertrophy & left ventricular atrophy
4. Without surgical repair, patient dies within first few
   months of life

Question 10

Tricuspid atresia

Answer 10

1. Complete occlusion of the tricuspid valve orifice due to unequal division of the atrioventricular canal
2. Concomitant ASD & VSD allows maintenance of
   pulmonary & systemic circulation
3. High mortality within first few weeks or months of life

Question 11

Persistent Truncus Arteriosus

Answer 11

Single great artery receiving blood from both ventricles

due to a failure of separation of truncus arteriosus into aorta & pulmonary trunk

Question 12

Coarctation of the aorta

Answer 12

1. A narrowing/constriction of the aorta which usually
   occurs distal to the branches of the arch of aorta
2. Results in hypertension of the upper extremities and hypotension in the lower extremities (weak pulses, intermittent claudication, coldness)
3. Left ventricular hypertrophy (due to pressure overload)
4. Radiographically, notching of the undersurfaces of the ribs evident (due to dilation of intercostals arteries involved in anastomosis to bypass coarcation)
5. Ejection systolic murmur

Question 13

Pulmonary Stenosis & Atresia

Answer 13

1. May occur in isolation or as part of a more complex
   anomaly (e.g. Tetralogy of Fallot)
2. Right ventricular hypertrophy (due to pressure overload)

Question 14

Aortic Stenosis & Atresia results in?

Answer 14

Left ventricular hypertrophy (due to pressure overload)