Morita K, Koyanagi K, Sakamoto Y, Wakabayashi K, Tanaka K, Sasaki T, Horikoshi S, Matsui M, Arai T
Department of Cardiac Surgery, Jikei University School of Medicine, Tokyo, Japan.
Nihon Kyobu Geka Gakkai Zasshi. 1991 Mar;39(3):266-75.
This 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.
本研究旨在评估在8只成年犬中，将游离的、经血管重建的背阔肌（LD）移植物置于左心室运动障碍节段，以增强左心室局部功能的能力。预先处理30天的背阔肌用胸廓内动脉和右心耳进行血管重建。游离移植物缝合在因结扎左前降支冠状动脉而产生的左心室前外侧壁缺血区域。以25和50Hz的猝发频率、1:1、2:1和3:1的同步率对移植物进行起搏。通过在缺血区域放置超声晶体和测量血流动力学参数，评估同步起搏的LD移植物对局部心肌功能和血流动力学的影响。在移植物同步起搏期间测量血管重建的胸背动脉血流速度（TDA血流）。在未对移植物进行起搏时，缺血区域出现收缩期膨出：缩短百分比（%S）=-9.5±3.6%。以25和50Hz的猝发频率对移植物进行起搏，导致缺血的左心室心肌被动节段缩短：%S分别为+3.9±1.9%（p<0.01，与未起搏值相比）和+5.5±1.9%（p<0.01，与未起搏值相比）。以50Hz的猝发频率对移植物进行起搏时，左心室压力从74±14mmHg增加到83±15mmHg（p<0.01）。在起搏心动周期中，主动脉峰值血流也平均增加了30±6%。与未对移植物进行起搏的模式不同，在1:1同步起搏期间，TDA血流模式在舒张期占主导。然而，起搏开始后TDA血流速度值增加，达到对照值的270±38%。总之，本研究表明，经血管重建的游离LD移植物有能力在收缩期对抗左心室壁应力进行收缩，并增强运动障碍节段的左心室局部功能。并且在心脏收缩期对移植物进行同步起搏期间，可以维持对移植物的充分血液灌注。
