The pericardium is the most frequent site of metastatic involvement of the heart in primary lung cancer.3
In one study, pericardial lesions were either the immediate or contributory cause of death in 86% of patients with symptomatic pericardial effusion.4
Cardiac tamponade has previously been considered to be rare as a presenting feature of malignancy, but epidemiological evidence regarding the true incidence of this mode of presentation is lacking. Important differential diagnosis of patients presenting with cardiac failure and hypotension of unknown aetiology should include pulmonary embolism, right ventricular infarction, constrictive pericarditis and malignant cardiac tamponade secondary to tumours, uraemia, autoimmune disorders or tuberculosis. A MEDLINE search done by Balghith et al
revealed only 17 cases reported in the English medical literature where cardiac tamponade was the initial presenting symptom of lung carcinoma.1
Yalcinkaya et al
reported the 19th case of lung carcinoma presenting as malignant tamponade in 2004.2
Malignancies spread to the myocardium or the pericardium by three important routes: (i) haematogenous, (ii) lymphatic and (iii) local extension. The latter two mechanisms are rare and are seen in carcinomas of the breast and the lung. Lung tumours spread to mediastinal lymph nodes from where retrograde spread occurs to the epicardial lymphatic plexus. Slow accumulation of large volumes of fluid may then occur. Among the histological variants of lung carcinoma, squamous carcinoma of the lung is typically endobronchial and may present as cardiac tamponade as it presents earlier with symptoms of haemoptysis, cough or bronchial obstruction. This is in contrast to the adenocarcinomas of the lung, which are more usually situated distally in the pulmonary parenchyma and have a higher chance of obstructing the lymphatics.5
The most common clinical features of malignant cardiac tamponade are non-specific. Malignant tamponade usually presents clinically with features of congestive cardiac failure as it develops as an acute event superimposed on a background of a large, slowly developing, pericardial effusion. Although abnormal ECGs were reported in over 90%, the changes were all non-specific apart from electrical alternans, which occurred in only 5%. Right ventricular diastolic collapse on echocardiography or cardiac catheterisation is evident prior to the development of hypotension or pulsus paradoxus. Mean arterial pressure is maintained in the early stages of tamponade. The recommended approach in such patients includes an immediate transthoracic echocardiogram followed by therapeutic pericardiocentesis.1
The fluid should be sent for diagnostic cytology. A haemorrhagic pericardial fluid in the absence of trauma or anticoagulants is associated with pericardial metastasis. In one series, a combination of cytology and measurement of carcinoembryonic antigen in the fluid was 100% sensitive and specific for malignancy.6
The approach to treatment has to be weighed against the patient's clinical condition and the underlying malignancy. In particular, the presence of pericardial effusion in patients with non-small cell lung cancer indicates a grave prognosis. Therefore, treatment with an initial pericardiocentesis followed by indwelling pericardial catheter is often recommended since surgery, radiation treatment and systemic chemotherapy are not always helpful in controlling the pericardial effusion secondary to lung cancer.7
There are several unusual features with this case. Most of the case reports of lung carcinoma presenting as malignant cardiac tamponade in the literature have been in male patients. It is most commonly caused by breast carcinomas in women. None of the case reports that presented as cardiac tamponade were complicated by hypercoagulability and pulmonary embolism contributing to further right ventricular dysfunction. Also the mean survival for patients with cardiac tamponade secondary to carcinoma of the lung or breast was 4 months; our patient survived only 4 days after the diagnosis. We believe that the pericardial effusion was reasonably longstanding and the pre-terminal decompensation was caused by the pulmonary embolus leading to additional right heart strain and her terminal decline.
- Cardiac tamponade is a rare presentation of malignancy though pericardial effusion is a common autopsy finding in advanced malignancy.
- The pericardium is the most common site of metastasis of heart in primary lung cancer. Tumours of the breast, leukaemia and lymphoma are also implicated.
- A high degree of suspicion is vital in patients presenting with cardiac failure and hypotension of unknown aetiology.
- An echocardiogram followed by pericardiocentesis is essential for management. A combination of diagnostic cytology and carcinoembryonic antigen is highly sensitive.