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Abstract
Objectives: We examined the relationship between atherosclerosis and provocation of coronary spasm as well as influence of coronary spasm on the onset of acute ischemic myocardial disease. Methods and Results: Coronary spasm was provoked in anesthetized normal Japanese white (JW) rabbits and WHHLMI rabbits, an animal model for coronary atherosclerosis and myocardial infarction, by injecting ergonovine during the infusion of norepinephrine through a marginal ear vein. A decrease in contrast flow in the left circumflex artery was observed on coronary angiograms. Ischemic changes were observed on the electrocardiogram of 29% (2/7) of JW and 79% (27/34) of WHHLMI rabbits. The frequency of coronary spasm was significantly high in rabbits with severe coronary plaques showing diffuse lesions. In addition, the degree of contraction of coronary strips with atherosclerotic plaques was higher than that of normal coronary strips excised from JW rabbits stimulated by a combination of ergonovine and norepinephrine. Left ventricle motility in these vasospasm-positive rabbits, which was evaluated with echocardiograms was decreased by 29% following the ergonovine injection (P<0.001), and every serum ischemic marker examined markedly increased 4 hours after the provocation of vasospasm. Conclusions: The results of the present study demonstrated that atherosclerotic coronary arteries were positively related to the provocation of vasospasm, and vasospasm in severe atherosclerotic coronary segments evoked angina pectoris and/or non-fatal myocardial infarction.
Highlights
The impact of coronary spasm on the onset of acute ischemic coronary events remains controversial
The results of the present study demonstrated that atherosclerotic coronary arteries were positively related to the provocation of vasospasm, and vasospasm in severe atherosclerotic coronary segments evoked angina pectoris and/or non-fatal myocardial infarction
Previous studies demonstrated that the degree of coronary plaques on angiography was a predictor of vasospasm [7] and intravascular ultrasound studies revealed that atherosclerosis was present at sites with coronary spasm even in the absence of angiographically significant coronary artery disease [8]
Summary
The impact of coronary spasm on the onset of acute ischemic coronary events remains controversial. The relationship between coronary spasm and acute ischemic coronary events as well as that coronary spasm and the degree of atherosclerotic lesions have not been elucidated in detail. Previous studies demonstrated that the degree of coronary plaques on angiography was a predictor of vasospasm [7] and intravascular ultrasound studies revealed that atherosclerosis was present at sites with coronary spasm even in the absence of angiographically significant coronary artery disease [8]. Since difficulties are associated with determining the relationship between coronary plaques and vasospasm as well as that between coronary spasm and angina pectoris in clinical studies because of ethical problems, suitable animal models needed to be developed to more clearly understand coronary spasm and angina pectoris
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