In a canine model, the development of collateral vessels during progressive coronary stenosis attenuated regional ischemia and hypokinesia, with full recovery of regional shortening at 25 +/- 4 days.
We studied the relationships among collateral flow, regional myocardial shortening and the grade of coronary stenosis during ameroid-induced chronic coronary constriction in 22 conscious dogs. A radiolucent ameroid, a Doppler flow probe and a cuff occluder were placed on the left circumflex coronary artery (LCx). Regional myocardial shortening and regional myocardial blood flow were assessed simultaneously using ultrasonic dimension gauges and the tracer microsphere technique, respectively, during temporary occlusion of the LCx. Regional hypokinesia and ischemia were attenuated as a function of time during progressive coronary stenosis. Fifty percent recovery and full recovery of regional shortening during occlusion were observed 19 +/- 3 and 25 +/- 4 days after instrumentation, respectively, when the endocardial blood flow recovered from 0.42 +/- 0.07 ml/min/g at 7 days to 0.56 +/- 0.07 and 0.80 +/- 0.05 ml/min/g, respectively. Greater than 75% coronary stenosis coincided with collateral development, as estimated from regional shortening rate and the appearance of angiographically opacified collaterals. Our study confirms that the development of collateral vessels reduces regional ischemia and hypokinesia induced during abrupt coronary occlusion in a canine model.
Tomoike et al. (1983) studied Ameroid-induced chronic coronary constriction (n=22). Ameroid-induced progressive coronary stenosis was evaluated on Regional myocardial shortening and regional myocardial blood flow during temporary occlusion. In a canine model, the development of collateral vessels during progressive coronary stenosis attenuated regional ischemia and hypokinesia, with full recovery of regional shortening at 25 +/- 4 days.