Brief coronary (C) occlusions (O) to (<15 min) are thought not to cause myocardial necrosis, but result in prolonged depression of regional mechanical function. This could be due to prolonged local ischemia. To analyze this problem, 8 conscious dogs were studied 2-4 wk after implantation of Doppler flow (F) probes and occluders on left (L) circumflex C artery, L atrial catheters, L ventricular pressure gauges and ultrasonic dimension transducers to measure segment length and wall thickness. During CO, ischemic zone (IZ) F fell by 70 ± 2% from .90 ± .05 ml/min/g, while IZ function showed paradoxical motion and absence of systolic wall thickening. Reperfusion was characterized by reactive hyperemia, subsiding by 12 min, and a parallel increase in end-diastolic wall thickness, subsiding by 15 min. At 30 min after reperfusion systolic wall thickening was depressed by .89 ± .25 mm from a control of 11.39 ± .78 mm. At this time IZ F was reduced by 19 ± 3%, ENDO F was depressed more than EPI F resulting in an abnormal ENDO/EPI ratio of 1.07 ± .06 (control = 1.24 ± .06). Systolic wall thickenig remained depressed for over 3 hr. Thus, following release of transient CO, abnormal regional perfusion in particular in the endocardium, may explain prolonged depression of reginal function, as refleted by impaired systolic wall thickening.
|Original language||English (US)|
|Pages (from-to)||No. 1472|
|State||Published - 1977|
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