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Bilateral Carcinoid Heart Disease in Advanced Functional Small Bowel Neuroendocrine Tumor Without Intracardiac Shunt: A Clinical Conundrum Case Report
Journal article   Open access   Peer reviewed

Bilateral Carcinoid Heart Disease in Advanced Functional Small Bowel Neuroendocrine Tumor Without Intracardiac Shunt: A Clinical Conundrum Case Report

Stefano H Byer, Mashkurul Haque, Ola Abdelkarim, Christian Anderson and Udhayvir S Grewal
European heart journal : case reports, Vol.10(1), ytaf679
01/2026
DOI: 10.1093/ehjcr/ytaf679
PMCID: PMC12836417
PMID: 41608071
url
https://doi.org/10.1093/ehjcr/ytaf679View
Published (Version of record) Open Access

Abstract

Background Carcinoid heart disease (CHD) is a known complication of advanced functional neuroendocrine tumors (NETs), almost exclusively affecting right-sided cardiac valves. Left-sided involvement is rare and usually attributed to intracardiac shunting or pulmonary sources of serotonin. This case report highlights a rare presentation of CHD involving left- and right-sided valves in the absence of an anatomic shunt or bronchopulmonary NET. Case Presentation A 67-year-old woman with a longstanding, functional, small bowel Grade 1 NET and metastatic liver and peritoneal disease presented with worsening dyspnea and peripheral edema. She had a 10-year disease history, previously managed with debulking surgery, somatostatin analogs, peptide receptor radionuclide therapy (PRRT), and everolimus. Echocardiography and cardiac MRI demonstrated extensive left- and right-sided valvular involvement with severe mitral regurgitation, moderate aortic and pulmonic regurgitation, and mild tricuspid regurgitation, yet without intracardiac shunt. An elevated Qp/Qs ratio of 2.6 was attributed to severe left-sided valvular regurgitation. The patient improved on diuretic therapy and was referred for surgical evaluation of valve replacement prior to additional systemic treatment. Discussion This case illustrates an atypical presentation of bilateral carcinoid valvulopathy in the absence of intracardiac shunting, likely due to overwhelming systemic serotonin from tumor burden. Although serotonin is typically inactivated in the lungs, extensive exposure may surpass this protective mechanism. The potential role of SSRIs remains inconclusive. Multidisciplinary coordination is essential for optimizing cardiac and oncologic outcomes, especially when systemic therapy such as PRRT is considered. Conclusion Left- and right-sided CHD may develop in patients with small bowel NETs even without anatomic shunting. High tumor burden and systemic serotonin exposure may override pulmonary inactivation, leading to left-sided involvement. Early recognition and multidisciplinary care are critical for effective management.
 Carcinoid heart disease neuroendocrine tumor intracardiac shunt PRRT case report

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