Transventricular non-transmural laser treatment of hypoperfused porcine myocardium acutely reduces left ventricular contractile function

Objective: Creation of non-transmural myocardial channels by lasers transmi tted through endovascular fiberoptics is a novel therapeutic option in the management of patients with coronary artery disease. The acute effect of tr ansventricular laser treatment (TvL) on coronary brood flow, myocardial met abolism and left ventricular function are not well established. Methods: In five anesthetized pigs, flow in the proximal left anterior descending coro nary artery (LAD) was reduced and maintained at 70% of baseline. A venous s hunt had previously been established draining the hypoperfused region, At 3 0 min of ischemia, non-transmural myocardial channels were created through the endocardium using a Ho:YAG laser. We measured (a) left ventricular, cen tral venous and arterial pressures, (b) ascending aortic, LAD and coronary venous blood flows, as well as (c) lactate concentration and blood gases in arterial and coronary venous blood, prior to ischemia (baseline), before a nd 30 min after TvL. Data (given as mean +/- SD) were analyzed with repeate d measures ANOVA. Results: Reduction of LAD blood flow resulted in reduced regional coronary venous blood flow and myocardial oxygen consumption, conv ersion of regional myocardial lactate uptake to release and adaptation of l eft ventricular contractility to a lower level. Following transventricular laser, the peak left ventricular systolic pressure declined from 86 +/- 12 to 77 +/- 11 mmHg (P < 0.05), its maximal first positive derivative (LV dP/ dt) declined from 900 +/- 221 to 763 +/- 127 mmHg/s (P < 0.05) and the stro ke volume decreased from 19.2 +/- 4.1 to 16.4 +/- 5.3 ml (P < 0.05), The ch anges in regional coronary venous flow, myocardial oxygen consumption and m yocardial lactate release after TvL were not significant compared to before TvL. Significant intramural hematomas and tissue destruction were found ar ound the channels at autopsy and by histologic examination. Conclusion: Tra nsventricular laser treatment of hypoperfused myocardium decreased left ven tricular contractility in the acute phase, possibly due to development of p erichannel hematomas and disruption of the wall architecture. In addition, TvL did not alter the regional myocardial oxygen supply/demand balance. The se results call for caution in the treatment of patients with coronary arte ry disease by transventricular Ho-YAG laser when there is significant impai rment of the left ventricular contractile function. (C) 1999 Elsevier Scien ce B.V. All rights reserved.