This is the external appearance of a normal heart.The This is the external appearance of a normal heart.The epicardial surface is smooth and glistening.The amount of epicardial surface is smooth and glistening.The amount of

epicardial fat is usual. The left anterior descending coronary epicardial fat is usual. The left anterior descending coronary artery extends down from the aortic root to the apex. artery extends down from the aortic root to the apex.

This is the normal appearance of myocardial fibers in This is the normal appearance of myocardial fibers in longitudinal section. Note the central nuclei and the longitudinal section. Note the central nuclei and the syncytial arrangement of the fibers, some of which syncytial arrangement of the fibers, some of which

have pale pink intercalated disks. have pale pink intercalated disks.

This distal portion of coronary artery shows This distal portion of coronary artery shows significant narrowing. Such distal involvement significant narrowing. Such distal involvement is typical of severe coronary atherosclerosisis typical of severe coronary atherosclerosis

This is a high magnification of the This is a high magnification of the aortic atheroma with foam cells and aortic atheroma with foam cells and

cholesterol clefts. cholesterol clefts.

A coronary artery has been opened longitudinally. The A coronary artery has been opened longitudinally. The coronary extends from left to right across the middle of coronary extends from left to right across the middle of

the picture and is surrounded by epicardial fat. the picture and is surrounded by epicardial fat. Increased epicardial fat correlates with increasing total Increased epicardial fat correlates with increasing total body fat. There is a lot of fat here, suggesting one risk body fat. There is a lot of fat here, suggesting one risk

factor for atherosclerosis. factor for atherosclerosis.

This is the left coronary artery from the aortic root on the left. This is the left coronary artery from the aortic root on the left. Extending across the middle of the picture to the right is the Extending across the middle of the picture to the right is the

anterior descending branch. This coronary shows severe anterior descending branch. This coronary shows severe atherosclerosis with extensive calcification. At the far right, atherosclerosis with extensive calcification. At the far right,

there is an area of significant narrowing. there is an area of significant narrowing.

This is coronary atherosclerosis with the complication This is coronary atherosclerosis with the complication of hemorrhage into atheromatous plaque, seen here in of hemorrhage into atheromatous plaque, seen here in

the center of the photograph. Such hemorrhage the center of the photograph. Such hemorrhage acutely may narrow the arterial lumen. acutely may narrow the arterial lumen.

Cross sections of this anterior descending coronary Cross sections of this anterior descending coronary artery demonstrate marked atherosclerosis with artery demonstrate marked atherosclerosis with

narrowing. This is most pronounced at the left in the narrowing. This is most pronounced at the left in the more proximal portion of this artery. In general, the more proximal portion of this artery. In general, the

worst atherosclerosis is proximal, worst atherosclerosis is proximal,

The anterior surface of the heart demonstrates an The anterior surface of the heart demonstrates an opened left anterior descending coronary artery.Within opened left anterior descending coronary artery.Within

the lumen of the coronary can be seen a dark red the lumen of the coronary can be seen a dark red recent coronary thrombosis. recent coronary thrombosis.

At high magnification, the dark red thrombus is apparent in At high magnification, the dark red thrombus is apparent in the lumen of the coronary. The yellow tan plaques of the lumen of the coronary. The yellow tan plaques of atheroma narrow this coronary significantly, and the atheroma narrow this coronary significantly, and the

thrombus occludes it completely. thrombus occludes it completely.

A thrombosis of a coronary artery is shown here in A thrombosis of a coronary artery is shown here in cross section. This acute thrombosis diminishes blood cross section. This acute thrombosis diminishes blood flow and leads to ischemia and/or infarction, marked flow and leads to ischemia and/or infarction, marked

clinically by the sudden onset of chest pain. clinically by the sudden onset of chest pain.

This myocardial infarction is about 3 to 4 days old. There is This myocardial infarction is about 3 to 4 days old. There is an extensive acute inflammatory cell infiltrate and the an extensive acute inflammatory cell infiltrate and the

myocardial fibers are so necrotic that the outlines of them are myocardial fibers are so necrotic that the outlines of them are only barely visible. only barely visible.

This is an intermediate myocardial infarction of 1 to 2 This is an intermediate myocardial infarction of 1 to 2 weeks in age. Note that there are remaining normal weeks in age. Note that there are remaining normal myocardial fibers at the top. Below these fibers are myocardial fibers at the top. Below these fibers are

many macrophages along with numerous capillaries many macrophages along with numerous capillaries and little collagenization. and little collagenization.

The myocardium beneath the endocardial surface at the top The myocardium beneath the endocardial surface at the top demonstrates pale fibrosis with collagenization following demonstrates pale fibrosis with collagenization following

healing of a subendocardial myocardial infarction. healing of a subendocardial myocardial infarction.

An aortic dissection may lead to hemopericardium when An aortic dissection may lead to hemopericardium when blood dissects through the media proximally. Such a massive blood dissects through the media proximally. Such a massive

amount of hemorrhage can lead to cardiac tamponade. amount of hemorrhage can lead to cardiac tamponade.

This is infective endocarditis. The aortic valve demonstrates This is infective endocarditis. The aortic valve demonstrates a large, irregular, reddish tan vegetation.Virulent organisms, a large, irregular, reddish tan vegetation.Virulent organisms,

such as Staphylococcus aureus, produce an "acute" bacterial such as Staphylococcus aureus, produce an "acute" bacterial endocarditis, while some organisms such as Streptococcus endocarditis, while some organisms such as Streptococcus

viridans produce a "subacute" bacterial endocarditis. viridans produce a "subacute" bacterial endocarditis.