EFFECT OF TACHYCARDIA ON REGIONAL FUNCTION AND TRANSMURAL MYOCARDIAL PERFUSION DURING GRADED CORONARY PRESSURE REDUCTION IN CONSCIOUS DOGS

被引:50
作者
CANTY, JM
GIGLIA, J
KANDATH, D
机构
[1] SUNY BUFFALO,SCH MED & BIOMED SCI,DEPT MED,BUFFALO,NY 14260
[2] SUNY BUFFALO,SCH MED & BIOMED SCI,DEPT PHYSIOL,BUFFALO,NY 14260
关键词
autoregulation; coronary pressure-function relation; coronary stenosis; myocardial flow-function relation;
D O I
10.1161/01.CIR.82.5.1815
中图分类号
R5 [内科学];
学科分类号
1002 ; 100201 ;
摘要
The purpose of the present study was to examine subendocardial flow and function during graded coronary pressure reduction to determine the effect of tachycardia on the lower autoregulatory pressure limit (critical coronary pressure) in unanesthetized dogs. During atrial pacing at a rate of 200 beats/min, subendocardial flow measured by radioactive microspheres averaged 1.55 ± 0.34 ml/min/g and remained unchanged as pressure was reduced over the autoregulatory plateau from 84 ± 10 to 59 ± 7 mm Hg. Further reductions in coronary pressure to below a critical coronary pressure of ~ 60 mm Hg were associated with concomitant reductions in subendocardial flow and the endocardial-epicardial flow ratio during tachycardia. Although regional function remained constant over the autoregulatory plateau, there was a rightward shift of the coronary pressure-function relation during ischemia in response to a steady-state increase in rate from 100 to 200 beats/min. Reductions in regional wall thickening began when coronary pressures reached 38 ± 7 mm Hg at a heart rate of 100 beats/min and 61 ± 6 mm Hg at a heart rate of 200 beats/min (p < 0.005). Similar critical coronary pressure values were obtained for subendocardial segment shortening. Relations between subendocardial flow and myocardial function measured by both transmural wall thickening and subendocardial segment shortening were linear during pacing at a heart rate of 200 beats/min with relative reductions in wall thickening related to reductions in subendocardial flow on a nearly one-to-one basis. The results of this study demonstrate that there is a shift in the lower limit of subendocardial autoregulation during tachycardia as manifest by the onset of subendocardial ischemia at a higher distal coronary artery pressure. The shift in critical coronary pressure relates to an increase in resting flow requirements due to increased demand and diminished subendocardial vasodilator reserve at any given coronary pressure secondary to a reduction in the time available for diastolic subendocardial perfusion during tachycardia.
引用
收藏
页码:1815 / 1825
页数:11
相关论文
共 22 条
[1]   EFFECT OF MAXIMAL CORONARY VASODILATION ON TRANSMURAL MYOCARDIAL PERFUSION DURING TACHYCARDIA IN AWAKE DOG [J].
BACHE, RJ ;
COBB, FR .
CIRCULATION RESEARCH, 1977, 41 (05) :648-653
[2]   INCREASED NUMBER OF MYOCARDIAL BLOOD-FLOW MEASUREMENTS WITH RADIONUCLIDE-LABELED MICROSPHERES [J].
BAER, RW ;
PAYNE, BD ;
VERRIER, ED ;
VLAHAKES, GJ ;
MOLODOWITCH, D ;
UHLIG, PN ;
HOFFMAN, JIE .
AMERICAN JOURNAL OF PHYSIOLOGY, 1984, 246 (03) :H418-H434
[3]   CORONARY PRESSURE-FUNCTION AND STEADY-STATE PRESSURE-FLOW RELATIONS DURING AUTO-REGULATION IN THE UNANESTHETIZED DOG [J].
CANTY, JM .
CIRCULATION RESEARCH, 1988, 63 (04) :821-836
[4]   AUTOREGULATION OF THE CORONARY CIRCULATION [J].
DOLE, WP .
PROGRESS IN CARDIOVASCULAR DISEASES, 1987, 29 (04) :293-323
[5]   MYOCARDIAL OXYGEN-TENSION DETERMINES THE DEGREE AND PRESSURE RANGE OF CORONARY AUTOREGULATION [J].
DOLE, WP ;
NUNO, DW .
CIRCULATION RESEARCH, 1986, 59 (02) :202-215
[6]   REGIONAL MYOCARDIAL PERFUSION AND WALL THICKENING DURING ISCHEMIA IN CONSCIOUS DOGS [J].
GALLAGHER, KP ;
MATSUZAKI, M ;
KOZIOL, JA ;
KEMPER, WS ;
ROSS, J .
AMERICAN JOURNAL OF PHYSIOLOGY, 1984, 247 (05) :H727-H738
[7]   PHYSIOLOGIC BASIS FOR ASSESSING CRITICAL CORONARY STENOSIS - INSTANTANEOUS FLOW RESPONSE AND REGIONAL DISTRIBUTION DURING CORONARY HYPEREMIA AS MEASURES OF CORONARY FLOW RESERVE [J].
GOULD, KL ;
LIPSCOMB, K ;
HAMILTON, GW .
AMERICAN JOURNAL OF CARDIOLOGY, 1974, 33 (01) :87-94
[9]   SIGNIFICANCE OF SUBENDOCARDIAL S-T SEGMENT ELEVATION CAUSED BY CORONARY STENOSIS IN DOG - EPICARDIAL S-T SEGMENT DEPRESSION, LOCAL ISCHEMIA AND SUBSEQUENT NECROSIS [J].
GUYTON, RA ;
MCCLENATHAN, JH ;
NEWMAN, GE ;
MICHAELIS, LL .
AMERICAN JOURNAL OF CARDIOLOGY, 1977, 40 (03) :373-380
[10]   THE EFFECT OF HYPERTENSION AND LEFT-VENTRICULAR HYPERTROPHY ON THE LOWER RANGE OF CORONARY AUTO-REGULATION [J].
HARRISON, DG ;
FLORENTINE, MS ;
BROOKS, LA ;
COOPER, SM ;
MARCUS, ML .
CIRCULATION, 1988, 77 (05) :1108-1115