title: Changes in myocardial contraction patterns in response to regional ischemia and sympathetic nerve stimulation.
abstract: We studied the effect of inferior cardiac nerve stimulation on global and regional left ventricular function before and after circumflex coronary arterial (CFX) occlusion in 12 pentobarbital-anesthetized cats. Regional function was evaluated by orthogonal sonomicrometry in the anterior midwall of the left ventricle and by two-dimensional short-axis echocardiography. CFX occlusion provoked hypokinesis in the nonischemic free wall adjacent to the dyskinetic ischemic region (17.6 +/- 2.3 vs. 34.6 +/- 2.2% preocclusion wall thickening; P < 0.01) and gradually improved systolic wall thickening toward the contralateral remote region, where the maximal hyperkinetic response was measured (52.9 +/- 4.4 vs. 32.5 +/- 3.3% preocclusion wall thickening; P < 0.001). In the anterior wall, remote region, hyperkinesis was predominant in longitudinal segments (8.1 +/- 0.8 vs. 2.3 +/- 0.6% preocclusion ejection shortening; P < 0.001) and slight in circumferential segments (11.0 +/- 0.7 vs. 9.1 +/- 0.6% preocclusion ejection shortening; P < 0.01). The postocclusion systolic wall thickening and segment-shortening pattern were not modified by sympathetic nerve stimulation, which increased cardiac output less after coronary occlusion, although contractility (dP/dt) increased markedly. In conclusion, the myocardial contraction pattern in ischemic and nonischemic regions after CFX occlusion is not much modified by sympathetic cardiac nerve stimulation.
authors.affiliation: Surgical Research Laboratory, University of Bergen, Haukeland Hospital, Norway.
authors.forename: S
authors.initials: S
authors.lastname: Birkeland
authors.forename: J
authors.initials: J
authors.lastname: Westby
authors.forename: S
authors.initials: S
authors.lastname: Faerestrand
authors.forename: K
authors.initials: K
authors.lastname: Grong
mesh_terms: D000818:Animals; D002415:Cats; D003326:Coronary Circulation; D003327:Coronary Disease / Q000503:physiopathology*; D004452:Echocardiography; D004558:Electric Stimulation; D006439:Hemodynamics; D008297:Male; D009200:Myocardial Contraction; D012016:Reference Values; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D016277:Ventricular Function, Left