Increasing left ventricular contractility and lowering coronary resistance maximized coronary systolic flow impediment and the energy of the backward-going compression wave in open-chest dogs.
How do changes in left ventricular contractility and coronary vascular resistance affect coronary systolic flow impediment in an open-chest dog model?
Left ventricular contractility and coronary resistance influence coronary systolic flow impediment by modulating the backward-going compression wave.
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 et al. (Fri,) conducted a other in Coronary dynamics (n=10). Paired pacing and intracoronary infusions of vasodilators/vasoconstrictors was evaluated on Coronary systolic flow impediment (CSFI) and energy of the backward-going compression wave (I(W-)). Increasing left ventricular contractility and lowering coronary resistance maximized coronary systolic flow impediment and the energy of the backward-going compression wave in open-chest dogs.
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