Acute effects of delayed reperfusion on myocardial infarct shape and left ventricular volume: a potential mechanism of additional benefits from thrombolytic therapy

Department of Medicine, State University of New York, Health Sciences Center, Stony Brook 1794-8171.

The purpose of this study was to characterize the effects of late reperfusion on myocardial infarct shape and to quantitate associated changes in left ventricular volume. Reperfusion was delayed until there was no salvage of ischemic myocardium. Dogs underwent 6.5 h of left anterior descending coronary artery occlusion (n = 5) or 5.5 h of occlusion and 1 h of reperfusion (n = 5). Infarct shape was measured with pairs of ultrasonic crystals implanted circumferentially in the mid myocardium. Infarct stiffness was determined from end-diastolic pressure-segment length curves produced by aortic clamping. Left ventricular volume was measured with three pairs of endocardial ultrasonic crystals and the effect of infarct shape change on left ventricular volume was determined. Infarct size, expressed as a percent of the area at risk, was similar in reperfused (97 +/- 1%) and nonreperfused (98 +/- 1%) hearts. After coronary artery occlusion, infarct segments became akinetic and functional dilation, measured as end-diastolic ultrasonic crystal separation, increased to a similar extent in reperfused (24 +/- 7%) and nonreperfused (19 +/- 3%) hearts. In 13 additional dogs that underwent reperfusion and instrumentation with endocardial ultrasonic crystals for volume measurement, left ventricular volume increased 42 +/- 6% over the preocclusion level (p less than 0.001). Within minutes of reperfusion, the infarct stiffened, infarct dilation decreased to 1 +/- 4% over the baseline preocclusion level (p less than 0.05 vs. prereperfusion) and left ventricular volume decreased to 16 +/- 11% over the baseline level (p less than 0.01 vs. postocclusion). Thus, coronary artery reperfusion reverses initial infarct dilation. Changes in infarct dilation occur immediately after reperfusion and are accompanied by infarct stiffening and a decrease in left ventricular volume. Reperfusion can affect infarct shape and stiffness at a point in time when myocardial salvage is no longer possible.

This article has been cited by other articles:

				M. E. Khalil, A. W. Basher, E. J. Brown Jr, and I. A. Alhaddad A remarkable medical story: benefits of angiotensin-converting enzyme inhibitors in cardiac patients J. Am. Coll. Cardiol., June 1, 2001; 37(7): 1757 - 1764. [Abstract] [Full Text] [PDF]

				J. G. Webb, L. A. Sleeper, C. E. Buller, J. Boland, A. Palazzo, E. Buller, H. D. White, J. S. Hochman, and for the SHOCK Investigators Implications of the timing of onset of cardiogenic shock after acute myocardial infarction: a report from the SHOCK Trial Registry J. Am. Coll. Cardiol., September 1, 2000; 36(3_Suppl_A): 1084 - 1090. [Abstract] [Full Text] [PDF]

				Y. Ohnishi, M. C. Butterfield, J. E. Saffitz, B. E. Sobel, P. B. Corr, and J. A. Goldstein Deleterious Effects of a Systemic Lytic State on Reperfused Myocardium : Minimization of Reperfusion Injury and Enhanced Recovery of Myocardial Function by Direct Angioplasty Circulation, August 1, 1995; 92(3): 500 - 510. [Abstract] [Full Text]

				I. A. Alhaddad, L. Tkaczevski, F. Siddiqui, R. Mir, and E. J. Brown Jr Aspirin Enhances the Benefits of Late Reperfusion on Infarct Shape : A Possible Mechanism of the Beneficial Effects of Aspirin on Survival After Acute Myocardial Infarction Circulation, June 1, 1995; 91(11): 2819 - 2823. [Abstract] [Full Text]

				T. Brzostek, F. Van de Werf, I. Scheys, L. Mortelmans, A. Aubert, J. S. Dubiel, and H. De Geest Determinants of Left Ventricular Function Two Weeks and One Year After an Acute Myocardial Infarction Angiology, January 1, 1995; 46(1): 27 - 36. [Abstract] [PDF]