P129 | ENDOCARDIAL LASER TREATMENT REDUCES LEFT VENTRICULAR CONTRACTILITY IN AN ACUTE PORCINE MODEL OF REGIONAL HYPOPERFUSION |
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| Ullevaal Hospital, Oslo, Norway | |
Objective: Creation of non-transmural myocardial channels by lasers transmitted through endovascular fiberoptics is being developed as a therapeutic option for patients with severe coronary artery disease. There have been no reports in the literature describing the acute effects of laser treatment by the endoventricular approach on the coronary blood flow, the myocardial metabolism and the left ventricular function.
Methods: In five anesthetized pigs, the flow in the proximal left anterior descending (LAD) artery was reduced and maintained at 70% of baseline. A venous shunt exclusively draining the hypoperfused region had previously been established from the anterior interventricular vein to the right atrium. At thirty minutes of ischemia, non-transmural channels were created in the ischemic myocardium from the endocardial to the epicardial direction using a pulsed Ho:YAG laser. We measured left ventricular pressure (LVP), central venous and arterial pressures, blood flow in the ascending aorta, the LAD and the venous shunt, lactate concentration and blood gases in the arterial and coronary venous blood, at baseline (prior to ischemia), before and 30 minutes after laser treatment.
Results:
| baseline | ischemia | ||
| before laser | after laser | ||
| LAD blood flow, ml·min-1 | 26.7 ± 8 | 18.2 ± 5.8 | 17.9 ± 6.1 |
| Coronary venous shunt blood flow, ml·min-1 | 18.2 ± 7.8 | 13.4 ± 6.2 | 14.5 ± 8.5 |
| Arterial pressure, mm Hg | |||
| systolic | 106 ± 17 | 98 ± 15 | 86 ± 13* |
| diastolic | 62 ± 13 | 55 ± 9 | 48 ± 6* |
| Aortic blood flow, l·min-1 | 2.15 ± 0.40 | 1.97 ± 0.36 | 1.67 ± 0.47* |
| Peak systolic LVP, mm Hg | 95 ± 15 | 86 ± 12 | 77 ± 11* |
| Maximal (+) dP/dt, mm Hg·sec-1 | 1038 ± 311 | 900 ± 221 | 763 ± 127* |
| Maximal (-) dP/dt, mm Hg·sec-1 | -1268 ± 265 | -1094 ± 210 | -900 ± 191* |
| Regional myocardial lactate production# | -6.38 ± 9.13 | 0.18 ± 7.42 | -1.90 ± 6.51 |
| Regional myocardial oxygen consumption# | 8754 ± 4682 | 7038 ± 3590 | 6927 ± 4281 |
values are mean ± SD; *, p < 0.05, vs. before laser, by two-tail paired t-test; #, in µmol·min-1; , myocardial lactate extraction.
The differences in heart rate, central venous pressure and systemic vascular resistance between the three time points were not statistically significant. Tissue swelling and hematoma were found in the treated region by inspection of the external heart surface in-vivo and by histologic examination.
Conclusions: Laser treatment of the hypoperfused myocardium using the endoventricular approach resulted in deterioration of left ventricular contractile function and development of regional tissue swelling and hematomas, but did not worsen the myocardial oxygen supply/demand balance. These results may have important implications for the selection of patients for the endovascular approach.
