Teaching Case

7 year old boy presented with a heart murmur.He was acyanotic with normal peripheral pulses.

A seven-year-old boy was referred by a GP for investigation of a heart murmur. He was asymtomatic, not cyanosed with normal peripheral pulses. Examination of the precordium revealed a forceful parasternal impulse with a widely split second heart sound, grade 3 ejection systolic murmur at the 2nd left intercostal space and a mid diastolic murmur at the left sternal edge. An echocardiogram revealed a large ostium secundum atrial septal defect with increased right ventricular pressure. Electrocardiograph showed a right bundle branch block. Within a few months he developed breathlessness and chest pain and hence underwent surgical correction with a pericardial patch for closure of the defect, as it was large.

ASD is an acyanotic congenital heart disease with left to right intracardiac shunting. It accounts for ten percent of all congenital heart diseases. They are classified based on the site of the defect. Ostium secundum is the commonest type and the defect is situated in the region of the fossa ovalis. Ostium primum and sinus venosus are the other two types of ASDs. Most ASDs are sporadic in origin however there are reports that suggest ostium secundum defects also have genetic component. The degree of left to right shunting is dependent on the size of the defect, the compliance of the ventricles and the presure difference between the two atria. Children with ASD are usually asymptomatic and are detected on routine examination. They may have mild dyspnoea, increased exercise intolerance or increased frequency of respiratory infections. Heart failure is extremely rare. Pulses are normal. There may be cardiomegaly. The characteristic auscultatory finding is wide splitting of 2nd heart sound that does not vary with respiration. An ejection systolic murmur or mid diastolic murmur may also be heard. The chest radiograph shows (1) mild cardiomegaly (2) pulmonary plethora more evident centrally (3) a triangular cardiac silhouette due in part to right heart and main pulmonary artery enlargement and no evidence of cardiomegaly. The cardiac enlargement is often best appreciated in the lateral view because the right ventricle protrudes anteriorly as it enlarges. The differential diagnoses include AV canal defect, VSD, PDA and other L→R shunts. ECG features include right axis deviation and incomplete right bundle branch block. Cross section echocardiogram reveals the size and site of the defect and the shunt can be demonstrated by Doppler. Complications such as pulmonary hypertension, arrhythmias, myocardial infarction, Eisenmenger complex and heart failure are very rare and occur in adults with uncorrected ASD. Treatment depends on the size of the defect and local expertise. Large defects are closed surgically. However there is an increasing use of endovascular device implantation in uncomplicated cases such as those without other associated cardiovascular defects that might need surgery and a suitable anatomy for application of a closing device.