Quick answer: carcinoid heart disease is damage to the heart valves caused by hormones released by a neuroendocrine tumour, usually once it has spread to the liver. It characteristically affects the right side of the heart — the tricuspid and pulmonary valves — because the lungs break down the responsible hormones before they reach the left side. It develops in a substantial minority of people with carcinoid syndrome, and it is the main cause of illness and death in that group. Valve surgery is the only treatment that repairs the damage, and it measurably improves survival.
This is general information for patients and families, not medical advice about a specific case. Carcinoid heart disease is rare and complex, and it is managed by specialist neuroendocrine tumour and cardiology teams. Use this to understand the terms and ask better questions.
When to Seek Medical Help
Contact your specialist team promptly if you have carcinoid syndrome and develop:
- New or worsening breathlessness, particularly on exertion or lying flat
- Swelling of the ankles, legs or abdomen, or rapid weight gain over days
- Increasing fatigue or reduced exercise tolerance
- Palpitations, or fainting
Seek emergency care for severe breathlessness at rest, chest pain, or collapse.
One critical thing to tell every doctor, dentist and surgeon you see: that you have a carcinoid tumour. Anaesthesia, surgery and some procedures can trigger a carcinoid crisis — a sudden, dangerous release of tumour hormones causing severe flushing, blood pressure collapse and bronchospasm. It is preventable with somatostatin analogue cover given beforehand, but only if the team knows. Carry documentation of your diagnosis.
What It Is, and Why the Right Side
Carcinoid tumours are a type of neuroendocrine tumour, most often arising in the small bowel or appendix, and less commonly in the lung, stomach or elsewhere. They secrete hormone-like substances, principally serotonin.
Normally the liver breaks these substances down before they reach the general circulation, so a localised tumour causes no systemic symptoms. Once the tumour spreads to the liver, that filtering is bypassed and the hormones enter the bloodstream. The resulting flushing, diarrhoea and wheezing is carcinoid syndrome.
Over time, those circulating hormones drive fibrous, plaque-like deposits onto the heart valve leaflets and the chordae that anchor them. The leaflets thicken, stiffen and retract, so they no longer close or open properly.
Here is the elegant part, and the answer to the question most patients ask: blood returning from the body passes through the right side of the heart, then the lungs, then the left side. The lungs inactivate serotonin. So the right-sided valves are exposed to high hormone concentrations and the left-sided valves are largely protected. That is why carcinoid heart disease is a right-sided disease.
Left-sided involvement does occasionally occur — most often when there is a hole between the upper chambers (a patent foramen ovale) allowing blood to bypass the lungs, or with a lung carcinoid tumour releasing hormones downstream of the lungs.
What happens to each valve
| Valve | Typical problem | Consequence |
|---|---|---|
| Tricuspid | Regurgitation — the leaflets retract and cannot close, so blood leaks backwards | The most common finding. Causes right heart enlargement and congestion |
| Pulmonary | Stenosis, regurgitation, or both | Obstructs outflow to the lungs and adds strain |
| Mitral and aortic | Usually spared | Involvement suggests a shunt or a lung primary tumour |
The end result is right-sided heart failure: the right ventricle enlarges and weakens, pressure backs up into the veins, and fluid accumulates in the legs, abdomen and liver.
How Common Is It?
- Carcinoid tumours themselves are uncommon, though incidence has risen, partly through better detection.
- Roughly a fifth to a half of people with carcinoid syndrome develop cardiac involvement, depending on the population studied and how carefully it is looked for. Rates have fallen since somatostatin analogues came into wide use.
- Diagnosis is typically in the fifth to seventh decade, and often delayed by two to three years, because early valve disease produces no symptoms and later symptoms — fatigue, breathlessness, swelling — are easily attributed to the cancer or its treatment.
That delay is exactly why screening rather than waiting for symptoms is the standard approach.
Symptoms
Carcinoid syndrome symptoms — flushing of the face and upper body, persistent watery diarrhoea, wheezing, abdominal cramping.
Cardiac symptoms, which appear later — breathlessness on exertion, fatigue and reduced exercise capacity, ankle and leg swelling, abdominal swelling from fluid, and sometimes a pulsation felt in the neck or an enlarged tender liver.
Important: significant valve damage is often present before any cardiac symptoms appear at all. Absence of symptoms does not mean absence of disease.
Diagnosis and Monitoring
- Echocardiogram. The definitive test, showing the thickened retracted leaflets and measuring severity and right ventricular function. Guidelines recommend a baseline echo for anyone with carcinoid syndrome, repeated periodically.
- NT-proBNP. A blood marker of cardiac strain, now widely used to screen and decide who needs echocardiography and how often. A normal level makes significant carcinoid heart disease unlikely.
- 24-hour urinary 5-HIAA. Measures the main breakdown product of serotonin. Higher levels are associated with greater risk of cardiac involvement. Certain foods and medicines interfere with the test, so follow the preparation instructions carefully.
- Cardiac MRI, where echo images are limited or before surgical planning.
- Imaging of the tumour itself, typically CT, MRI and specialised nuclear scans.
A reasonable question at your next appointment: when was my last echocardiogram, and when is the next one due?
Treatment
Care runs on three tracks at once, and understanding the split explains why controlling the syndrome does not fix the heart.
1. Controlling the tumour and its hormones
- Somatostatin analogues such as octreotide and lanreotide, the mainstay. They reduce hormone secretion, control flushing and diarrhoea, and slow tumour growth.
- Surgical removal or debulking of the primary tumour, potentially curative if caught before spread.
- Liver-directed treatments including embolisation or ablation of liver metastases.
- Peptide receptor radionuclide therapy (PRRT), targeted radiotherapy delivered to tumour cells.
- Telotristat, which reduces serotonin production, for diarrhoea not controlled by somatostatin analogues.
The key limitation: these control the hormone load and may prevent further valve damage, but they do not reverse damage already done. Fibrosed valve leaflets do not recover.
2. Managing right heart failure
Diuretics reduce fluid overload and relieve swelling and breathlessness, and salt and fluid intake may be adjusted. This is symptom control — it makes people more comfortable but does not alter the valve disease.
3. Valve replacement surgery
The only treatment that corrects the underlying problem, and the one with the clearest survival benefit. Damaged tricuspid and pulmonary valves are replaced, usually with tissue (bioprosthetic) valves. Studies from centres including Mayo Clinic have found valve replacement improves both symptoms and survival in carcinoid heart disease.
Timing is a genuine balance, weighing valve severity and right ventricular function against how well the cancer is controlled and overall fitness — which is why these decisions are made by multidisciplinary teams combining cardiology, cardiac surgery and neuroendocrine oncology. Operating before the right ventricle deteriorates gives better outcomes, so being referred early matters. Perioperative somatostatin analogue cover is used to prevent carcinoid crisis.
Outlook
Honestly stated: cardiac involvement worsens the outlook in carcinoid syndrome, and historically it was the leading cause of death in this group.
That picture has improved substantially. Somatostatin analogues, better imaging, earlier screening and valve surgery have all changed outcomes, and many people now live for years with well-managed disease. The factors that most affect prognosis are how well the tumour is controlled, the severity of valve disease at diagnosis, right ventricular function, and whether valve surgery is performed at the right time.
Because this is rare, care at a specialist neuroendocrine tumour centre with cardiology experience in it is associated with better outcomes. Asking for referral to such a centre is reasonable and worth doing.
Frequently Asked Questions
It is damage to the heart valves caused by hormones, principally serotonin, released by a neuroendocrine tumour once it has spread to the liver. Fibrous plaque-like deposits build up on the valve leaflets, which thicken, stiffen and retract so they no longer close or open properly. It characteristically affects the tricuspid and pulmonary valves and leads to right-sided heart failure.
Because the lungs inactivate serotonin. Blood returning from the body passes through the right side of the heart, then the lungs, then the left side — so the right-sided tricuspid and pulmonary valves are exposed to high hormone concentrations while the left-sided valves are largely protected. Left-sided involvement does occur occasionally, usually when a hole between the upper chambers lets blood bypass the lungs, or with a lung carcinoid tumour releasing hormones downstream.
Cardiac symptoms include breathlessness on exertion, fatigue and reduced exercise capacity, swelling of the ankles and legs, abdominal swelling from fluid, and sometimes a pulsation in the neck or an enlarged tender liver. These appear alongside carcinoid syndrome symptoms of flushing, watery diarrhoea and wheezing. Crucially, significant valve damage is often present before any cardiac symptoms appear, so absence of symptoms does not mean absence of disease.
Echocardiography is the definitive test, showing thickened retracted leaflets and measuring severity and right ventricular function. Guidelines recommend a baseline echo for anyone with carcinoid syndrome, repeated periodically. NT-proBNP, a blood marker of cardiac strain, is widely used to decide who needs an echo and how often, and a normal level makes significant disease unlikely. A 24-hour urinary 5-HIAA test measures serotonin breakdown products, with higher levels associated with greater cardiac risk.
No. Somatostatin analogues such as octreotide and lanreotide control hormone secretion, relieve flushing and diarrhoea, slow tumour growth and may prevent further valve damage — but they cannot reverse damage already done, because fibrosed valve leaflets do not recover. Diuretics relieve fluid overload and breathlessness but likewise do not alter the valve disease. Valve replacement surgery is the only treatment that corrects the underlying problem.
It is the treatment with the clearest survival benefit in carcinoid heart disease, and studies from specialist centres have found it improves both symptoms and survival. Damaged tricuspid and pulmonary valves are usually replaced with tissue valves. Timing balances valve severity and right ventricular function against how well the cancer is controlled, so decisions are made by multidisciplinary teams. Operating before the right ventricle deteriorates gives better outcomes, which is why early referral matters.
A sudden dangerous release of tumour hormones causing severe flushing, collapse in blood pressure and bronchospasm. It can be triggered by anaesthesia, surgery and some procedures. It is preventable with somatostatin analogue cover given beforehand, but only if the medical team knows about your tumour. Tell every doctor, dentist and surgeon you see that you have a carcinoid tumour, and carry documentation of your diagnosis.
Cardiac involvement worsens the outlook in carcinoid syndrome and was historically the leading cause of death in this group, but the picture has improved substantially. Somatostatin analogues, better imaging, earlier screening and valve surgery have all changed outcomes, and many people now live for years with well-managed disease. Prognosis depends most on tumour control, valve severity at diagnosis, right ventricular function and whether surgery happens at the right time. Care at a specialist neuroendocrine centre is associated with better outcomes.
Sources
- StatPearls — Carcinoid Heart Disease, NCBI Bookshelf.
- National Cancer Institute — Gastrointestinal carcinoid tumours.
- NIH Genetic and Rare Diseases Information Center — Carcinoid syndrome.
- MedlinePlus — Carcinoid syndrome.
- NHS — Neuroendocrine tumours.
- MedlinePlus — Heart valve surgery.
Last updated: August 2026. Written by Maja Zayeri, who covers cardiovascular topics and is not a clinician. Reviewed for accuracy by our editorial team; not reviewed by a named clinician. This article is general information about a rare condition and is not medical advice, a diagnosis or a treatment plan. Carcinoid heart disease is managed by specialist neuroendocrine tumour and cardiology teams, and all decisions about testing, medication, monitoring and surgery belong with them.
