Differential effects of a segment of slow conduction on reentrant ventricular tachycardia in the rabbit heart

Article

关键词: EPICARDIAL BORDER ZONE;    RESETTING RESPONSE PATTERNS;    INFARCTED HUMAN HEART;    MYOCARDIAL-INFARCTION;    EXCITABLE GAP;    EXTRACELLULAR POTASSIUM;    CANINE INFARCTS;    FIXED OBSTACLE;    PURKINJE-CELLS;    PORCINE HEART;   

DOI  :  10.1161/01.CIR.99.7.949

来源: SCIE

【 摘 要 】

Background-The purpose of this study was to compare differential effects of a segment of slow conduction during ventricular tachycardia (VT) due to depression of the action potential and electrical uncoupling. Methods and Results-In 33 Langendorff-perfused rabbit hearts, a ring of anisotropic left ventricular subepicardium was created by a cryoprocedure. Reentrant VT was produced by incremental pacing. Slow conduction in a segment of the ring was created by selective perfusion of the LAD with 10 mmol/L potassium or 0.75 mmol/L heptanol. As a result, VT cycle length increased from 193+/-34 to 235+/-37 ms (potassium) and 227+/-42 ms (heptanol). Reset curves were made by applying premature stimuli proximal to the area of depressed conduction. Tn a ring of uniform anisotropic tissue, the reset curve was almost completely flat. Electrical uncoupling of part of the ring (nonuniform anisotropy) resulted in a mixed reset curve. In both substrates, early premature beats failed to terminate VT. Depression of part of the ring by increasing K+ resulted in a completely sloped reset curve, indicating a gap of partial excitability. Under these conditions, in 19 of 24 hearts, premature beats terminated VT by conduction block in the high K+ area. Conclusions-The nature of the area of slow conduction determines the type of reset response and the ability to terminate VT.

【 授权许可】

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