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.
The incidence of carcinoid tumours is approximately 1 in 75 000 of the population1 of whom about 50% develop carcinoid syndrome.
approximately 50% of these patients develop carcinoid heart disease which typically causes abnormalities of the right side of 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 direct metastatic involvement of the heart.
The characteristic pathological findings are endocardial plaques of fibrous tissue that may involve the tricuspid valve, pulmonary valve, cardiac chambers, venae cavae, pulmonary artery, and coronary sinus.
The fibrous reaction may involve not only the valve leaflets, but also the subvalvar apparatus including the tendinous chords and papillary muscles of the tricuspid valve, and more rarely the mitral valve in cases with left sided involvement.
The preferential right heart involvement is most likely related to inactivation of the vasoactive substances by the lungs. In the 5?10% of cases with left sided valvar pathology, one should suspect either extensive liver metastases, bronchial carcinoid, or a patent foramen ovale.
Carcinoid symptoms typically occur between the fifth and seventh decades of life with a mean age of 55?60 years.
Echocardiography plays a central role in the diagnostic and prognostic evaluation of this condition.
In patients with carcinoid heart disease, right atrial and right ventricular enlargement is present in up to 90% of cases and ventricular septal wall motion abnormalities are seen in almost half of the cases.?The tricuspid valve leaflets and subvalvar structures are often thickened, shortened and retracted, leading to incomplete coaptation and usually moderate or severe tricuspid regurgitation.
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Carcinoid tumours are rare neuroendocrine malignancies mostly arising within the gastrointestinal system, particularly the ileum and appendix
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The carcinoid syndrome, characterised by cutaneous flushing, secretory diarrhoea, and bronchospasm, occurs secondary to the paraneoplastic effects of vasoactive tumour products such as serotonin and only occurs in the presence of metastatic spread
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Raised mean 24 hour urinary excretion of 5-hydroxyindole acetic acid (5-HIAA), an end product of serotonin metabolism, is a key diagnostic finding
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Carcinoid heart disease occurs in approximately 50% of patients with the carcinoid syndrome and usually heralds a worsening prognosis
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The vast majority of patients with carcinoid heart disease develop right heart failure caused by severe dysfunction of the tricuspid and pulmonary valves
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Palliation of symptoms and prolonged survival can be achieved with appropriate medical treatment and valvar surgery in selected patients with carcinoid heart disease