Comparison of early systolic and early diastolic regional function during regional ischemia in a chronically instrumented canine model

Abstract

Depressed left ventricular function during the early part (first third) of both systole and diastole in the resting state have been reported to be sensitive indicators of coronary artery disease in patients with normal global function at rest. To evaluate the possible mechanisms of these findings, 11 dogs were chronically instrumented with segmental function sonomicrometers in the left circumflex and left anterior descending coronary artery distribution, circumflex coronary flow probes and cuff occluders, aortic flow probes and ventricular pressure transducers. Percent segmental function during the first third of systole and diastole was measured in the control state and with graded circumflex artery flow reductions. Significant decreases in early systolic function with ischemia in the circumflex artery distribution were partially offset by compensatory augmented shortening in the left anterior descending artery distribution. With ischemia in the circumflex distribution, there was prolonged contraction into diastole manifested as impaired relaxation. Simultaneously, in the left anterior descending artery distribution, there was minimal compensatory enhanced relaxation. These results suggest that early systolic dysfunction in ischemic segments may be offset by enhanced function in nonischemic segments, rendering minimal, if any, change in global systolic function. Early diastolic dysfunction in ischemic segments exceeds compensatory changes in nonischemic areas by two-to-four-fold. Hence, early diastolic functional indexes may be more sensitive indicators of ischemia at rest than early systolic functional indexes.

Perioperative Assessment of Myocardial Deformation

“…64 For example, early diastolic SR was significantly reduced in ischemic myocardial segments. 62 And substantial delays in early LV relaxation during exercise in patients with stable effort angina, measured as a radial strain diastolic index, provided a sensitive method for detection of myocardial ischemia.…”

“…Attenuated longitudinal strain measurements provide an early indication of subendocardial ischemia, 61–63 though nonischemic myocardial regions may compensate for impaired systolic function with increased shortening. 60,64 In patients with coronary artery disease, longitudinal segmental strain cutoffs of −14.1% and −6.65% detected ischemic and infarcted myocardial segments, respectively. 65 Patients with recent anterior wall myocardial infarction demonstrate reduced radial and longitudinal strain, while greater reduction in circumferential strain is seen if LVEF is reduced.…”

Myocardial Ischemia in Patients with Diastolic Dysfunction and Heart Failure

“…The second mechanism takes longer (20-30 min) and is induced by perfusion ischemia (abrupt cessation of oxygenated blood flow). These differences are likely related to the presence/ absence of pressurized coronary vasculature, and/or tissue hypoxia, which may result in increased cytosolic calcium levels, tissue acidosis, as well as availability of ischemic preconditioning and changes in diastolic filling time [27,28].…”

Differential effects of synchronized coronary sinus retroperfusion on regional myocardial function during brief occlusion of the left anterior descending and circumflex coronary arteries

“…The protocol we used for chronic sterile instrumentation of experimental animals has been described previously in detail [27,28] and conforms to the position of the American Heart Association on research animal use. In the present study, eight conditioned mongrel dogs of either sex underwent general anesthesia with nitrous oxide and methoxyflurane.…”