The late sequalae of pulmonary hypertension

Clinical History

A 52-year-old woman was investigated for symptoms suggestive of right-sided heart failure (shortness of breath, lower limb oedema, oligura) shortly after she started taking NSAIDs for ankle pain. Plain radiography, electrocardiography, echocardiography, cardiac catheterisation and cross-sectional imaging revealed a right-to-left shunt secondary to an ostium secundum atrial septal defect.

Imaging Findings

We present the case of a 52 year old female which was being investigated for shortness of breath, lower limb oedema, oliguria, and tiredness. No chronic medical or surgical history of note was available at the time of assessment. The patient had been complaining of right ankle pain following minor trauma, and has been on Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) for three weeks.

The patient was noted to be tachycardic. Auscultation of the chest revealed bi-basal crepitations. Symmetrical pitting lower limb oedema was also evident. Atrial flutter, incomplete right bundle branch block and right axis deviation were seen on electrocardiography. Plain chest radiography (Fig. 1) showed a prominent pulmonary trunk, prominent main pulmonary arteries, a 3 cm peripheral pulmonary nodule in the mid-zone of the right lung, and moderate cardiomegaly. A CT was performed in order to characterise the peripheral pulmonary nodule further, and the findings were very suggestive of a hamartoma (Fig. 2-3).

She was therefore examined by a cardiologist. Echocardiogram showed a large atrial septal defect (3.2 cm in diameter) with a left to right shunt, a grossly distended pulmonary artery, a grossly dilated right and hypertrophied right ventricle, a grossly dilated right atrium and very high pulmonary pressures.

Formal cardiac catheterisation studies confirmed the echocardiographic findings. Left atrial oxygen saturation was measured at 85.5%, pulmonary artery systolic pressure at 120 mmHg (normally 18-25 mmHg), mean pulmonary pressure at 80 mmHg (normally 12-16 mmHg), and aortic pressure 140/90 mmHg. The coronary arteries were normal.

Discussion

Pulmonary arterial hypertension (PAH) has been defined as a mean pulmonary arterial pressure above 25 mmHg at rest [1]. Our patient had a mean pulmonary pressure of 80 mmHg secondary to pulmonary hypertension as a complication of a large atrial septal defect (ASD).

Three types of ASD are recognised - ostium secundum defects (the commonest), ostium primum defects, and sinus venosus defects. ASDs can go undiagnosed for decades, as in this case, due to initial subtle symptoms and signs. Symptoms often develop gradually, and are related to the defect itself (cardiac arrhythmias, valvular disease) or to the resultant pulmonary hypertension. In our case, administration of NSAIDs precipitated the symptoms and signs of right heart failure due to the fluid overload associated with such agents.

Pulmonary hypertension can be classified using the WHO classification [2] (Fig. 4). Causes can be divided into precapillary and postcapillary. Precapillary causes include primary PAH, pulmonary thromboembolic disease, pulmonary emphysema, and chronic interstitial lung disease. Postcapillary causes include cardiac septal defects, left atrial myxoma/thrombus, left ventricular failure, constrictive pericarditis, pulmonary veno-occlusive disease, pulmonary vein stenosis, anomalous drainage of the pulmonary veins and fibrosing mediastinitis [3].

The radiological features of PAH are similar, regardless of the cause. Plain radiography may demonstrate enlargement of the central pulmonary arteries with 'pruning' of the peripheral branches. A dilated right ventricle would be reflected by apposition of more than one third of the anterior heart border to the sternum, on the lateral chest radiograph. Another feature suggestive of PAH would be increase in diameter of the right interlobar artery (> 15 mm). The left interlobar artery is difficult to appreciate on frontal chest radiographs. A normal chest radiograph does not rule out PAH [3].

Contrast enhanced CT is much more useful in depicting the pulmonary vasculature. PAH can be also defined as the pulmonary trunk exceeding 29 mm in diameter on CT. The widest portion of the main pulmonary artery within 3 cm of the bifurcation was used to determine the value [4,5]. In chronic PAH the enlarged central pulmonary arteries may develop thrombus and peripheral calcification. The right ventricle is often dilated.

The role of cardiac MRI in the evaluation of pulmonary hypertension is comparable to that of echocardiography. The cardiac output, pulmonary arterial pressure and right ventricular thickness/mass can be accurately determined on MRI. These parameters can be used to assess the severity of PAH [6].

Formal pulmonary angiography is often reported as being the 'gold standard' in imaging of the pulmonary vasculature. The role of this technique in PAH has been recently questioned, due to the wide availability of modern less invasive cross sectional imaging modalities. Inter-observer variability can reach 10-15%. Complications (2-5%) following pulmonary angiography seem to be related to direct cannulation of the right heart and pulmonary artery, and these vary from cardiac arrhythmias to cardiac perforation leading to tamponade. Patients with high pulmonary pressures are at a higher risk for tamponade [7].

Differential Diagnosis List

Final Diagnosis

Pulmonary hypertension secondary to a secundum atrial septal defect

URL:	https://eurorad.org/case/8571
DOI:	10.1594/EURORAD/CASE.8571
ISSN:	1563-4086