Final answer:
A true ventricular aneurysm is composed of scar tissue with collagenous and smooth fibers, potentially including some residual smooth muscle fibers and vasculature. This scar tissue replaces the contractile myocardium, leading to reduced heart function.
Step-by-step explanation:
The composition of the tissue in a true ventricular aneurysm primarily consists of a layer of scar tissue made up of collagenous and smooth fibers, with the possible presence of some smooth muscle fibers, nervi vasorum, and vasa vasorum. The myocardium, which is the thickest layer of the heart composed of cardiac muscle cells, is typically weakened or replaced by this scar tissue in an aneurysm. While healthy myocardial tissue is rich in contractile cardiac muscle cells and supported by a framework of collagenous fibers and blood vessels, with an outer layer known as the epicardium and an inner lining called the endocardium, the aneurysmal tissue does not effectively contribute to the contractile force of the heart. This alteration in structure can lead to reduced cardiac function and compromised blood flow, with potential implications for heart contractility, known as negative inotropic factors.