Acute Bacterial Endocarditis
The compact heart exhibits the left ventricle and related valves. The aortic valve's non-coronary cusp is ulcerated and perforated, with friable vegetations. Below this, a perforation extends into the right atrium above the tricuspid valve. The other aortic cusp is also thickened. This is an acute bacterial endocarditis with aortic cusp and atrioventricular perforations.
Rheumatic Endocarditis
The dissected heart shows a thickened mitral valve, blood, and fibrin deposits on the left atrial wall, and a clot in the left auricular appendage due to atrial fibrillation. MacCallum's plaques, irregular thickenings in the deep layers of the endocardium, are present on the atrial wall.