Tricuspid and pulmonary valve regurgitation usually occurs as a secondary phenomenon caused by dilatation of the valve ring secondary to right ventricular failure or pulmonary hypertension, respectively. Primary diseases of the tricuspid or pulmonary valves are uncommon, but the more likely causes might include congenital abnormalities, rheumatic heart disease, or infective endocarditis. Carcinoid heart disease is a rare, but interesting and important cause of intrinsic tricuspid and pulmonary valve disease leading to significant morbidity and mortality caused by right heart failure. When treated medically, and in appropriate cases surgically, significant benefits in overall quality of life and long term survival can be achieved. We review the current literature regarding the pathophysiological basis of the disease, the cardiovascular complications, and the currently available treatment strategies.

AETIOLOGY AND PATHOPHYSIOLOGY

Carcinoid tumours are rare neuroendocrine malignancies arising from neural crest amine precursor uptake decarboxylation cells. Approximately 90% of all carcinoid tumours are located in the gastrointestinal system of which the most common sites are the appendix and terminal ileum. Other less common sites include the bronchus and gonads. The most malignant of the carcinoid tumours tend to arise from the ileum and must be invasive or metastasise to produce the carcinoid syndrome which is characterised by facial flushing, intractable secretory diarrhoea, and bronchoconstriction. The incidence of carcinoid tumours is approximately 1 in 75 000 of the population¹ of whom about 50% develop carcinoid syndrome. Once the carcinoid syndrome has developed, approximately 50% of these patients develop carcinoid heart disease which typically causes abnormalities of the right side of the heart.

Usually, only carcinoid tumours that invade the liver result in pathological changes to the heart. The cardiac manifestations are caused by the paraneoplastic effects of vasoactive substances such as 5-hydroxytryptamine (5-HT or serotonin), histamine, tachykinins, and prostaglandins released by the malignant cells rather than any …