Cardiac fibrosis

Overview
Cardiac fibrosis refers to an abnormal thickening of the heart valves due to inappropriate proliferation of cardiac fibroblasts.

Pathophysiology
These cells secrete collagen, and normally function to provide structural support for the heart. When over activated this process causes thickening and fibrosis, primarily on the tricuspid valve, but also occurring on the pulmonary valve, eventually leading to right-sided heart failure.

Certain diseases such as gastrointestinal carcinoid tumors, which release large amounts of serotonin into the blood, produce a characteristic pattern of mostly right sided cardiac fibrosis which can be identified at autopsy. This pathology has also been seen in certain african tribes who eat foods containing excess amounts of serotonin.

Some appetite suppressant drugs such as fenfluramine and chlorphentermine induce a similar pattern of cardiac fibrosis, by over-stimulating 5HT2B receptors on the cardiac fibroblast cells. These drugs consequently tended to cause increased risk of heart valve damage and subsequent heart failure, which eventually led to them being withdrawn from the market.

A compound found in red wine, resveratrol has been found to slow down the development of cardiac fibrosis.