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Cor pulmonale: a variation on a theme

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Q1: What investigations would help to identify the underlying cause of cardiac failure in this patient?

All patients with heart failure require identification of the underlying cause, so that treatment can be focused appropriately. In the present instance, electrocardiographic stigmata such as right bundle branch block, and a change in mean axis from its previous value of −15 degrees to its present value of +121 degrees (fig 1), suggested a diagnosis of pulmonary embolism, possibly recurrent, with consequent cor pulmonale. The coexistence of type 1 respiratory failure, with arterial oxygen and carbon dioxide partial pressures of 7.3 kPa and 3.0 kPa, respectively, appeared to support this provisional diagnosis.

Figure 1

Electrocardiogram showing atrial fibrillation and right bundle branch block.

Q2: Could there be a link between the atrial fibrillation and evolution of the changes in the QRS axis?

When cor pulmonale complicates pulmonary thromboembolism it is typically characterised by type 1 respiratory failure, as in the present case.1 Atrial fibrillation, though more commonly complicated by systemic embolism (as a result of thrombus formation in the left atrial appendage), can occasionally be complicated by thrombosis within the right appendage, as in six of 90 patients with atrial fibrillation who had evaluable echocardiograms in the study reported by de Divitiis et al,2pulmonary embolism being a potential complication. In the present instance, this was one of the potential aetiopathogenetic pathways for cor pulmonale.

Treatment and progress

She was anticoagulated and also treated with diuretics and continuous administration of oxygen. However, despite a good diuretic response, characterised by a 8 kg fall in body weight, she deteriorated, and died on day 54.

Postmortem findings

Severe coronary heart disease was documented, and the right ventricle was shown to contain a myxoid tumour measuring 11 × 10 × 7 cm (see fig 2). The lungs were infiltrated by multiple nodules, up to 1.5 cm in diameter, composed of similar material. Histologically, the right ventricular tumour was composed of malignant glandular epithelium (see fig 3) with large, pleomorphic, and vesicular nuclei characterised by moderate mitotic activity. There had obviously been secretion of vast amounts of mucinous material. An acute inflammatory infiltrate also extended throughout the tumour. Tumour emboli were identified within the lumen of pulmonary blood vessels (see fig 4). Extrathoracic primary or secondary tumour could not be identified in the gastrointestinal tract, pancreas, ovary, uterus, thyroid, or elsewhere.

Figure 2

Necropsy specimen showing myxomatous tumour in the right ventricular cavity (arrowed).      

Figure 3

Histology of the right ventricular tumour showing papillary glands (arrowed) on the endocardial surface (haematoxylin and eosin; magnification × 200).

Figure 4

Histology of the metastatic tumour (arrowed) in the lumen of a pulmonary blood vessel (haematoxylin and eosin; magnification × 100).

Discussion

On the basis of antemortem chest radiography, and antemortem echocardiography, this patient already had a provisional diagnosis of cor pulmonale attributable to pulmonary metastatic disease,3 with associated intracardiac mass of unknown origin. At necropsy, the crucial distinction was between primary and secondary cardiac neoplastic disease, the latter being by far the more common entity.4 Within the heart itself, malignant infiltration of the endocardium is much less likely than involvement of either the myocardium or the pericardium.5 The right ventricular endocardium is the logical site for metastases originating from the systemic circulation, as in colonic carcinoma,6while blood borne metastases originating from the pulmonary circulation would first have to be seeded to a systemic location (for example, the adrenal gland), before metastasising to the right side of the heart.7 Exceptionally, as in the case reported by Ragle, a primary tumour in the right lung can spread to the right atrium, the carcinoma cells having been “carried by the systemic circulation, and not by the pulmonary circulation”.8 Assuming that our patient, also, had a primary pulmonary tumour, a similar mode of spread could have accounted for secondary deposits in the right ventricle, with subsequent tumour embolisation to the rest of the lung. Although primary myxoma of the right ventricle9 seemed a plausible alternative diagnosis, with tumour embolism as a complication,10 the histological appearances were not typical, and the presence of mitotic activity also appeared to mitigate against this diagnosis.9

Final diagnosis

Cor pulmonale resulting from pulmonary tumour metabolism.

References

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