Hemodynamic and Humoral factors in Coronary Collateral Development

点击翻译按钮获取中文摘要

The effects of pre-existing collateral and the perfusion size on the ischemia-induced collateral development were studied in a canine model. The dogs were instrumented under sterile surgery with pairs of ultrasonic crystals to measure regional wall motion in the territory of the left circumflex(LCX) and left anterior descending coronary arteries. An implantable miniature micromanometer was used to measure left ventricular (LV) pressure. Two to 3weeks after surgery, 2min coronary occlusion (CO) of the LCX was repeated every 32 min automatically using an AM/AM telemetry command system. Regional wall motion and LV pressure were monitored via a FM/FM telemetry system consecutively day and night. The functional state of pre-existing collaterals which estimated by the level of % reduction of regional wall motion at the end of the first 2min CO, ranged from-11 to -141%. The perfusion size of the LCX ranged from 35 to 54%. Number of coronary occlusion needed for collateral development was exponentially related to the functional state of pre-existing collaterals(r=0.77, P<0.01), but not to the perfusion size.When the collateral function was functionally matured in the same model as above, an episode of 2 min coronary occlusion was stopped. After 24 hours'interruption of occlusion stimuli, the functional state of collaterals remained deteriorated. Thus, the presence of ischemic stimuli is important to maintein the developed state of collateral function.To elucidate how the diseased state such as hyperlipidemia(WHHL rabbits) modulates the speed of collateral development, we adopted rabbit for an experimental model.We successfully devised miniaturized sensors for assessing instantaneous coronary bood flow or ventricular pump function. Thus, we are able to study not only regional wall motion, but also humoral factors related to collateral function in purely-bred animal models.