NONOBSTRUCTIVE CAUSES OF ISCHEMIC HEART DISEASE



Situations associated with increased left ven­tricular pressure and wall tension, a decrease in diastolic perfusion pressure, and/or an increase in left ventricular mass (for example, aortic stenosis) may cause myocardial ischemia by altering the balance of oxygen supply and demand. In addi­tion, conditions in which substrate delivery is de­creased (for example, hypotension, anemia, and carbon monoxide poisoning) may cause myocar­dial ischemia, especially if preexisting coronary lesions are present.

A syndrome of myocardial infarction with an-giographically normal coronary arteries exists. Approximately 2 per cent of patients with my­ocardial infarction demonstrate no obstructive le­sions on coronary arteriography. These patients tend to be young, have a low incidence of coro­nary risk factors, and often have no history of an­gina pectoris prior to infarction. The prognosis for survival after the acute event is usually good. The cause is unknown, but possible etiologies include coronary emboli, coronary artery spasm, coronary artery disease in smaller vessels beyond the res­olution of coronary arteriography, and coronary arterial thrombosis with recanalization.