Carcinoid Heart Disease

Carcinoid heart disease is a genuinely distinctive entity in this section — a systemic, hormone-driven process that produces an almost exclusively right-sided valvular pattern, with a Doppler signature specific enough to recognize on its own, and a prognosis sobering enough that its onset is itself treated as a major clinical turning point.

What Carcinoid Heart Disease Is

Carcinoid tumors are rare neuroendocrine tumors that secrete vasoactive compounds, including serotonin, with an estimated incidence of 1.0 to 8.4 per 100,000. They’re classified by embryologic site of origin — foregut (bronchus, stomach, proximal duodenum), midgut (distal duodenum, jejunum, ileum, appendix, ascending colon), and hindgut (transverse and descending colon, rectum) — with midgut tumors, particularly from the ileum and appendix, the most common.

Carcinoid syndrome — flushing, diarrhea, bronchospasm, and hypotension from vasoactive compounds entering the systemic circulation — occurs in 30% to 40% of patients. Up to two-thirds of patients with carcinoid syndrome go on to develop carcinoid heart disease, and carcinoid heart disease can itself be the presenting problem in up to 20% of carcinoid tumor patients. The onset of carcinoid heart disease is a marker of sharply increased mortality, with a median survival of only 14 months once it develops — worth holding in mind as the reason this diagnosis is treated with real urgency rather than as an incidental valvular finding.

Why the Right Side, Almost Exclusively

This is genuinely mechanistic, not coincidental. The vasoactive compounds responsible for the cardiac damage — serotonin, prostaglandins, histamine, and bradykinin — are normally inactivated in the lungs. Most patients with carcinoid heart disease have liver metastases, and compounds released from those metastases reach the right-sided valves at full concentration via the hepatic vein, before ever passing through the lungs for clearance — explaining why right-sided lesions predominate so strongly.

Left-sided lesions occur in up to 15% of patients, and are specifically associated with:

• A right-to-left intracardiac shunt (allowing compounds to bypass the lungs entirely)
• A bronchial carcinoid (bypassing hepatic filtering altogether)
• Very high circulating vasoactive compound levels, overwhelming pulmonary clearance capacity

A genuinely important exception worth knowing: primary ovarian carcinoid can produce cardiac involvement without any liver metastases at all, since its vasoactive compounds drain directly into the inferior vena cava rather than through the portal/hepatic circulation — a route that reaches the right heart just as directly as the more typical hepatic metastasis pathway.

Laboratory correlation: plasma serotonin and urine levels of its primary metabolite, 5-hydroxyindoleacetic acid (5-HIAA), are higher in patients with carcinoid heart disease. A urine 5-HIAA level of 300 µmol/24 hours or greater is an independent predictor of carcinoid heart disease development or progression — a specific laboratory threshold worth knowing alongside the echocardiographic findings themselves, since it identifies exactly which patients warrant closer cardiac surveillance.

The Underlying Pathology

Typical lesions are fibrous, plaque-like areas of endocardial thickening, depositing most commonly on the surface of valve leaflets but also capable of affecting the subvalvular apparatus and cardiac chambers directly. This produces leaflet thickening from tip to base, with resulting straightening and stiffening; the chordae and papillary muscles can become thickened, shortened, or fused. The combined effect is retraction and impaired coaptation, producing a genuine combination of both regurgitation and stenosis together — not simply one or the other, which is worth keeping in mind when characterizing the valve’s overall dysfunction.

Echocardiographic Findings by Valve

Tricuspid Valve — Most Commonly Affected

Tricuspid regurgitation is the most common abnormality. In severe cases, the leaflets become genuinely “frozen,” with limited motion in both systole and diastole — producing severe TR with a distinctive “dagger-shaped” continuous-wave Doppler profile, reflecting rapid pressure equilibration between the right atrium and right ventricle. See Tricuspid Regurgitation for the general severity-grading framework this specific pattern fits into.

• Mild or moderate tricuspid stenosis may coexist — see Tricuspid Stenosis for the standard assessment approach.
• RA and RV dilation are commonly seen, a consequence of the chronic severe regurgitation — see Evaluation of the Right Ventricle for the standard assessment approach this finding feeds directly into, particularly for tracking replacement timing.
• Isolated leaflet involvement has also been described, producing an eccentric TR jet rather than the more typical central, laminar jet of diffuse leaflet disease.

Pulmonary Valve — Second Most Commonly Affected

Both pulmonary regurgitation and pulmonary stenosis may be present — see Pulmonary Regurgitation and Pulmonary Valve Stenosis for the standard grading approaches each follows. Plaque deposition at the pulmonary root can restrict orifice size, with associated post-stenotic dilation of the pulmonary artery. Doppler imaging genuinely enhances detection of pulmonary valve involvement, particularly when the valve itself is poorly visualized on 2D imaging.

A genuine technical pitfall worth knowing explicitly: pulmonary stenosis severity can be underestimated when significant tricuspid regurgitation coexists, since the resulting low cardiac output across the pulmonary valve reduces the transpulmonary gradient independent of the valve’s true anatomic severity. Tricuspid and pulmonary stenosis and regurgitation are otherwise graded using the same standard criteria applied to any other cause.

Left-Sided Valves — Rare, and Worth Investigating When Present

Left-sided lesions are far less frequent, and when present are often associated with a patent foramen ovale — worth actively screening for whenever left-sided valvular findings are seen in a patient with known carcinoid disease, given how directly this connects to the right-to-left shunting mechanism described above.

Myocardial Metastases

Occur in approximately 4% of carcinoid heart disease patients, and can be seen with or without accompanying valvular involvement — worth a deliberate look at the myocardium itself, not just the valves, in a comprehensive carcinoid assessment.

When to Image, and How Often

Current recommendations encourage baseline transthoracic echocardiography for all carcinoid syndrome patients with any of the following: clinical features suggesting cardiac involvement, increased B-type natriuretic peptide, or increased 5-HIAA levels — followed by regular echocardiographic monitoring thereafter. This is a genuinely proactive screening approach, directly motivated by how sharply prognosis worsens once carcinoid heart disease is established, rather than waiting for overt symptoms to prompt imaging.

Valvular Intervention

Valve replacement is recommended when severe valvular dysfunction is associated with symptoms, or with progressive RV dilation or dysfunction. Survival in carcinoid heart disease has genuinely improved over recent decades with earlier valve replacement — worth knowing as a reason not to delay intervention once criteria are met.

Prosthesis choice has a genuinely evolving evidence base worth knowing honestly: early concern that carcinoid disease would directly affect bioprosthetic valve tissue led to greater use of mechanical prostheses. However, a large series found similar reoperation rates and survival between bioprosthetic and mechanical valves over roughly 4.5 years of follow-up — a finding attributed in part to improvements in the medical management of the underlying carcinoid disease itself, rather than the prosthesis type being irrelevant on its own. See Prosthetic Heart Valves for the general surveillance approach that applies regardless of which prosthesis type is chosen.

Postoperative surveillance: early TEE to establish baseline valvular function, followed by echocardiography every 3 to 12 months, depending on the specific clinical scenario.

Transcatheter options are increasingly used in patients at high surgical risk, including transcatheter pulmonary valve replacement and valve-in-valve replacement (pulmonary or tricuspid) for bioprosthetic degeneration. Balloon valvuloplasty has been reported successful in a limited number of cases for patients with symptomatic pulmonic stenosis and elevated right-sided pressures, aiming to palliate symptoms and reduce right-sided pressures rather than serve as definitive therapy.

How to Approach the Suspected Carcinoid Heart Disease Patient: A Practical Sequence

1. Image proactively in any carcinoid syndrome patient with cardiac symptoms, elevated BNP, or elevated 5-HIAA — don’t wait for overt valvular symptoms to prompt the first study.
2. Assess the tricuspid valve first and most carefully, given its predominant involvement — look specifically for leaflet thickening, retraction, and the characteristic “frozen” appearance in severe disease, and confirm severe TR with the dagger-shaped CW Doppler signature when present.
3. Evaluate the pulmonary valve with particular attention to Doppler, since 2D visualization is often limited — and reassess pulmonary stenosis severity with the knowledge that coexisting severe TR can cause genuine underestimation.
4. Actively look for both stenosis and regurgitation together at each affected valve, rather than characterizing the lesion as purely one or the other.
5. Screen for a PFO whenever left-sided valvular findings are present, given the shunt-mediated mechanism that explains most left-sided disease.
6. Assess the myocardium directly, not just the valves, given the real incidence of myocardial metastases.
7. Establish regular surveillance intervals once carcinoid heart disease is confirmed, and reassess valve replacement criteria as RV size and function evolve over time.
8. Following valve replacement, obtain early postoperative TEE for a baseline, then continue structured echocardiographic follow-up at 3- to 12-month intervals.

Clinical Importance

Carcinoid heart disease rewards understanding the actual biology behind the echo pattern, not just memorizing “right-sided valves, dagger-shaped Doppler” as isolated facts — the lung’s role in inactivating these vasoactive compounds is what explains nearly everything else on this page, from why the right side predominates almost exclusively to why a bronchial carcinoid or a right-to-left shunt can break that rule. Given how sharply prognosis changes once this diagnosis is established, recognizing the pattern early — and recognizing when pulmonary stenosis severity might be masked by coexisting tricuspid disease — is where echocardiography makes a genuine difference for these patients.