More than just a big heart

A young man's routine chest x-ray shows an enlarged heart shadow.

CLINICAL SCENARIO

A 22-YEAR-OLD graphic designer from the UK applied for a permanent residency visa and at his medical assessment an enlarged heart shadow was picked up on a routine chest x-ray.

He is generally well and asymptomatic with no history of cardiac problems and no risk factors. There is no family history of heart disease.

Clinical examination reveals a soft systolic ejection murmur over the pulmonary area and the impression of a split second heart sound which is relatively fixed.

Inspection of the chest x-ray confirms a large cardiac shadow, but the lung fields are relatively clear other than slightly more prominent vascular markings in the hilar areas.

This patient subsequently had an ECG (below).

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Figure 1: ECG of the 22-year-old male

DIAGNOSIS

Question: Based on the ECG above, the clinical presentation and examination, which of the following is the likely diagnosis?

1. Pulmonary valve stenosis
2. Aortic stenosis
3. Atrial septal defect
4. Ventricular septal defect
5. Patent ductus arteriosus

DISCUSSION

This patient underwent echocardiography for further investigation, and a large atrial septal defect (ASD) was discovered (answer no. 3 is correct).

The ECG findings that support this diagnosis are partial right bundle branch block and a rightish axis. Right axis deviation is usually present with an ostium secundum ASD, whereas left axis deviation is usually present with an ostium primum defect.

The echo also demonstrated quite markedly enlarged right-sided heart chambers, and this finding is usually indicative of a haemodynamically significant ASD with a significant left to right shunt.

The clinical findings of a pulmonary systolic murmur and a fixed second heart sound are fairly classical findings in this condition.
A small ASD would not necessarily cause any chest x-ray abnormality, but the large flow across this defect has resulted in an enlarged right atrium and right ventricle leading to an enlarged cardiac shadow.

This patient will be referred for closure of his ASD utilising a percutaneous closure device.