Before any of the many forms of cardiac dissection is applied (1-14), coronary arteries should be inspected for calcification and tortuosity. If angiography is indicated, the procedure must be performed before dissection of the coronary vessels and preferably before fixation of the heart.
POSTMORTEM CORONARY ANGIOGRAPHY This important method is described in detail in Chapter 12.
DISSECTION OF CORONARY ARTERIES In subjects younger than 30 yr, in whom the cause of death is noncardiac, the coronary arteries may be opened longitudinally. Otherwise, the vessels should be cut in cross-section at 3-5 mm intervals. Calcified vessels that cannot be readily cut with a scalpel should be stripped off the heart and decalcified for at least 24 h before cutting.
GRADING OF CORONARY OBSTRUCTION A four-point system is applied, by 25% increments of narrowing in cross-sectional area (15). A grade-4 lesion indicates stenosis of at least 75% and is considered severe, whereas a grade-4 lesion of 90% represents critical stenosis. As a rule, grade-4 lesions should be documented microscopically. Depending on the number of major epicardial vessels with grade-4 lesions, a heart may have severe 1-vessel, 2-vessel, or 3-vessel disease. Severe left main disease is equivalent to 2-vessel disease, and its coexistence with grade-4 disease in the other three coronary arteries represents severe 4-vessel disease.
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