Effects of left ventricular contractility and coronary vascular resistance on coronary dynamics.
Wave-intensity analysis, which separates upstream from downstream events and defines their interaction, has been used to study the effects of changes in left ventricular (LV) contractility (E(max)) and left circumflex coronary artery resistance (R(LCx)) on the coronary systolic flow impediment (CSFI). In 10 anesthetized, open-chest dogs, we measured coronary, aortic, and LV pressures, coronary velocity (Flowire), and flow. E(max) was increased by paired pacing and R(LCx) was modulated by intracoronary infusions of vasodilators (adenosine and nitroglycerin) and a vasoconstrictor (phenylephrine). When both E(max) and R(LCx) were varied, CSFI and the energy of the backward-going compression wave (I(W-)) were greatest at the highest levels of E(max) and the lowest levels of R(LCx). I(W-) was proportional to the CSFI. We conclude that contractility and coronary resistance change CSFI by modulating the backward-going compression wave.
Sun
Yi-Hui
YH
Department of Medicine, University of Calgary Health Sciences Centre, Calgary, Alberta, Canada T2N 4N1.
Anderson
Todd J
TJ
Parker
Kim H
KH
Tyberg
John V
JV
D000465:Algorithms; D000818:Animals; D003326:Coronary Circulation / Q000187:drug effects / Q000502:physiology*; D004285:Dogs; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects / Q000502:physiology*; D014655:Vascular Resistance / Q000187:drug effects / Q000502:physiology*; D014661:Vasoconstriction / Q000502:physiology; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014664:Vasodilation / Q000502:physiology; D014665:Vasodilator Agents / Q000494:pharmacology; D016277:Ventricular Function, Left / Q000187:drug effects / Q000502:physiology*
D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents