• K Morita, K Koyanagi, Y Sakamoto, K Wakabayashi, K Tanaka, T Sasaki, S Horikoshi, M Matsui, and T Arai.
• Department of Cardiac Surgery, Jikei University School of Medicine, Tokyo, Japan.
• Nihon Kyobu Geka Gakkai Zasshi. 1991 Mar 1; 39 (3): 266-75.

AbstractThis study was performed to evaluate the ability of a free revascularized Latissimus Dorsi (LD) graft placed on dyskinetic segments of the left ventricle to augment regional left ventricular performance in 8 adult dogs. LD muscles preconditioned for 30 days were revascularized with the internal mammary artery and right atrial appendage. The free graft was sutured on the ischemic area of the left ventricular anterolateral wall, produced by ligation of the left anterior descending coronary artery. Grafts were paced at a burst frequency of 25 and 50 Hz, at a synchronization ratio of 1:1, 2:1, and 3:1. Effects of synchronously paced LD grafts on regional myocardial performance and hemodynamics were evaluated by placing ultrasonic crystals on the ischemic area and hemodynamic parameters. The flow rate of revascularized thoracodorsal artery (TDA flow) was measured during synchronously pacing of the grafts. Systolic bulging was shown in the ischemic area without graft pacing: %shortening (%S) = -9.5 +/- 3.6%. Graft pacing at a burst frequency of 25 and 50 Hz resulted passive segmental shortening of the ischemic left ventricular myocardium: %S = +3.9 +/- 1.9% (p less than 0.01, vs values without pacing) and +5.5 +/- 1.9% (p less than 0.01, vs values without pacing), respectively. The left ventricular pressure increased from 74 +/- 14 mmHg to 83 +/- 15 mmHg (p less than 0.01) with graft pacing at a burst frequency of 50 Hz. The peak aortic flow also was augmented by an average of 30 +/- 6% at paced cardiac cycles. The pattern of TDA flow during 1:1 synchronous pacing was changed to be dominant in diastolic, unlike the pattern without graft pacing. Values of TDA flow rate, however, increased after the initiation of pacing and reached 270 +/- 38% of control values. In conclusions, this study shows that a revascularized free LD graft has an ability to contract in systole against the left ventricular wall stress, and to augment regional left ventricular performance in dyskinetic segments. And sufficient blood perfusion to the grafts can be maintained during synchronously pacing of the grafts in cardiac systole.

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