Carcinoid heart disease. A cardiologist's viewpoint

Cardiac Roles of Serotonin (5-HT) and 5-HT-Receptors in Health and Disease

Serotonin acts solely via 5-HT₄-receptors to control human cardiac contractile function. The effects of serotonin via 5-HT₄-receptors lead to positive inotropic and chronotropic effects, as well as arrhythmias, in the human heart. In addition, 5-HT₄-receptors may play a role in sepsis, ischaemia, and reperfusion. These presumptive effects of 5-HT₄-receptors are the focus of the present review. We also discuss the formation and inactivation of serotonin in the body, namely, in the heart. We identify cardiovascular diseases where serotonin might play a causative or additional role. We address the mechanisms which 5-HT₄-receptors can use for cardiac signal transduction and their possible roles in cardiac diseases. We define areas where further research in this regard should be directed in the future, and identify animal models that might be generated to this end. Finally, we discuss in what regard 5-HT₄-receptor agonists or antagonists might be useful drugs that could enter clinical practice. Serotonin has been the target of many studies for decades; thus, we found it timely to summarise our current knowledge here.

Quadruple Valve Involvement in a Patient With Severe Carcinoid Heart Disease

We report on the case of a 48-year-old male patient suffering from a severe carcinoid heart disease with involvement of the four valves. The primary carcinoid tumor was diagnosed in the ileum. The patient developed a moderate stenosis and severe insufficiency of the tricuspid valve, a severe insufficiency of the pulmonary valve, and a moderate insufficiency of the mitral and aortic valves. Ultimately, a stentless pulmonary valve replacement was performed, as well as a tricuspid valve replacement with a pericardial prosthesis and aortic and mitral valve plasty. The patient recovered well and he was discharged from hospital on day 10.

Carcinoid heart disease: an update

BACKGROUND

Carcinoid tumours are a poorly defined collection of lesions, histopathologically indistinguishable from gastroentero-pancreatic neuroendocrine tumours. In this report, we discuss epidemiology and survival, clinical presentation, carcinoid valvular heart disease (CVHD), histopathological considerations and treatment options.

METHODS

Review and update of the literature.

RESULTS

The term carcinoid suggests a disease entity, but with increasing knowledge it becomes progressively confusing. To avoid further confusion, it is advisable to define these tumours using differentiation, stage, primary site, known tumour products and an associated clinical syndrome. Incidence varies between 0.8 and 1.9/100,000 population. About 20% present with metastases, with a 5-year survival varying between 15% and 35%. Metastatic disease frequently accompanies the carcinoid syndrome (flushing, diarrhoea, wheezing and CVHD). CVHD incidence is about 50%, and seems unrelated to disease duration and tumour mass. An aetiological relation of CVHD with urinary 5-HIAA remains to be confirmed. Resection is the only curative option. Surgery can also offer prolonged palliation and is needed to restore bowel transit in obstructive/ischaemic bowel problems. Adequate palliation of hormone-related symptoms can also be achieved by somatostatin analogues, meta-iodo-benzyl-guanidine preparations and interferon-alpha formulations, all with a 70% response rate. Embolization of liver metastases has led to objective responses in about 50% of patients, but is accompanied by significant side effects.

CONCLUSIONS

Most patients are cured by surgery. Symptom relief is the main target in metastatic disease and can be achieved by a range of equally potent biologically active medications, debulking surgery and hepatic embolization.

Carcinoid Heart Disease

Carcinoid syndrome originates from metastatic carcinoid tumors localized in the gastrointestinal system, pancreas, biliary vessels, bronchi, ovaries, and testes; it is characterized by flushing, telangiectasias, diarrhea, bronchoconstriction, and fibrous endocardial plaques in the heart. Cardiac involvement is detected by echocardiography in over 50% of patients with this syndrome. Right-sided valvular heart disease occurs frequently in patients with carcinoid syndrome, involving most commonly the tricuspid and pulmonary valves. Involvement of the left-sided valves rarely occurs. Medical therapy for carcinoid heart disease includes digitalis and diuretics for congestive heart failure symptoms; the effects of carcinoid syndrome can be treated with the use of somatostatin analogues. Conventional chemotherapy has been of little beneficial value, with response rates of only 10% to 30%. The use of octreotide, a long-acting and potent somatostatin analogue, is a major advance in the management of carcinoid tumors. In addition to providing effective symptom relief in malignant carcinoid syndrome, octreotide can also be used for diagnostic purposes. Despite its expense, octreotide is the current agent of choice for the treatment of this condition. Analogues with different receptor specificities and pharmacokinetics hold promise for the future. Valve surgery is the only definitive treatment for intractable right-sided heart failure. Although cardiac surgery carries high perioperative mortality, marked symptomatic improvement occurs in survivors. Surgical intervention therefore should be considered in the appropriate patients when cardiac symptoms become severe. Balloon valvulotomy in patients with severe pulmonary artery stenosis often results in palliation of symptoms; however, surgery still is required often in these patients.

Gastrointestinal carcinoid tumors: current management strategies

BACKGROUND

Carcinoid or neuroendocrine tumors of the gastrointestinal tract, although characteristically indolent, are also quite heterogeneous both with respect to histologic and endocrine features and with respect to clinical presentation and behavior.

PURPOSE

This study was undertaken to review and summarize the current literature on classification controversies, site-specific carcinoid presentation and behavior, and diagnostic and management strategies for primary and advanced carcinoid tumors and the carcinoid syndrome.

RESULTS

For carcinoid tumors, oncologic results depend on the location of the primary tumor, extent of locoregional and metastatic disease, functioning status of the tumor, and the feasibility of complete surgical extirpation. Whereas favorable survival rates are typically observed for appendiceal and rectal primaries, less favorable rates are often observed for colonic and ileal tumors. A search for additional tumors is generally advised because multiple carcinoids and second neoplasms are not uncommon. Because of the indolent nature of the tumor and because these therapies have been shown to improve quality and quantity of life, otherwise fit patients with advanced carcinoid disease should be treated with aggressive medical and surgical therapies. Development of a malignant carcinoid syndrome indicates the presence of a functionally active carcinoid tumor and portends a poor prognosis.

CONCLUSION

Gastrointestinal carcinoids, although malignant, behave differently from other carcinomas. Results are highly variable and must be individualized according to the site of the primary tumor, extent of spread, and general condition of the patient. A prolongation of quality life can often be accomplished through aggressive medical and surgical therapies.

Carcinoid tumours

The use of long-acting and potent somatostatin analogues is a major advance in the management of carcinoid tumours. In addition to providing effective symptom relief in malignant carcinoid syndrome, octreotide can also be used for diagnostic purposes. Despite its expense, octreotide is the current agent of choice for the treatment of this condition while analogues with different receptor specificities and pharmacokinetics hold promise for the future. Gastric carcinoids have aroused interest because of their experimental association with chronic hypergastrinaemia, a condition now commonplace because of the widespread use of H2-blockers and proton-pump inhibitors. This subject is reviewed. The slow evolution of many tumours demands prolonged follow-up and the active use of a variety of palliative interventions. These include measures such as hepatic and cardiac surgery, which might be deemed inappropriate for patients with other types of metastatic malignancy. Interferons may have a role when first-line treatments have failed. Chemotherapy is, generally, of limited value.

Carcinoid heart disease. Correlation of high serotonin levels with valvular abnormalities detected by cardiac catheterization and echocardiography

BACKGROUND

Although serotonin has been postulated as an etiologic agent in the development of carcinoid heart disease, no direct evidence for different ambient serotonin levels in cardiac and noncardiac patients has been reported to date.

METHODS AND RESULTS

The present study reviews our experience with 604 patients in the Duke Carcinoid Database. Nineteen patients with proven carcinoid heart disease (by cardiac catheterization and/or echocardiogram) were compared with the remaining 585 noncardiac patients in the database with regard to circulating serotonin and its principal metabolite, 5-hydroxyindole acetic acid (5-HIAA). No significant demographic differences existed between the cardiac and noncardiac groups; however, typical carcinoid syndrome symptoms (ie, flushing and diarrhea) were almost threefold more common in the cardiac group (P < .001). Compared with the noncardiac group, heart disease patients demonstrated strikingly higher (P < .0001) mean serum serotonin (9750 versus 4350 pmol/mL), plasma serotonin (1130 versus 426 pmol/mL), platelet serotonin (6240 versus 2700 pmol/mg protein), and urine 5-HIAA (219 versus 55.3 mg/24 h) levels. The spectrum of heart disease among the 19 patients showed a strong right-sided valvular predominance, with tricuspid regurgitation being the most common valvular dysfunction (92% by cardiac catheterization; 100% by echocardiogram).

CONCLUSIONS

These data suggest that serotonin plays a major role in the pathogenesis of the cardiac plaque formation observed in carcinoid patients.

Carcinoid heart disease: early failure of an allograft valve replacement

A woman who had carcinoid syndrome and carcinoid heart disease underwent tricuspid and pulmonary valve replacements with a xenograft and a cryopreserved allograft, respectively. Within 3 months of the operation severe pulmonary regurgitation and pulmonary hypertension refractory to medical therapy developed. Autopsy found the biomechanical tricuspid valve to be free of disease but the allograft in the pulmonary position was involved by carcinoid heart disease in a fashion similar to the excised native pulmonary valve.

Successful balloon dilatation of the pulmonary valve in carcinoid heart disease

Percutaneous balloon dilatation of the pulmonary valve resulted in long lasting benefit in a 40-year-old patient with carcinoid heart disease. Concomitant aggressive therapy for her metastatic carcinoid tumour may explain why the clinical outcome was better than previous reports.