Vrobel T R, Ring W S, Anderson R W, Emery R W, Bache R J
Am J Physiol. 1980 Nov;239(5):H621-7. doi: 10.1152/ajpheart.1980.239.5.H621.
Because of the previous suggestion that subendocardial perfusion may be inadequate in the hypertrophied heart, this study was carried out to examine the response of transmural myocardial blood flow to pacing induced tachycardia in dogs with chronic left ventricular hypertrophy. Myocardial hypertrophy, produced by banding the ascending aorta of puppies at 5-6 wk of age, resulted in an 87% average increase in relative left ventricular mass compared with the control dogs. Myocardial blood flow was examined during ventricular pacing at heart rates of 100, 200, and 250 beats/min using radionuclide-labeled microspheres. Mean blood flow per unit myocardial mass was similar in the two groups of dogs at a heart rate of 100 beats/min and increased regularly during pacing in both groups of animals. Increasing heart rates did not change the transmural pattern of myocardial blood flow in the normal dogs, but in the animals with left ventricular hypertrophy pacing at 250 beats/min resulted in a significant redistribution of perfusion away from the subendocardium, with the ratio of subendocardial/subepicardial blood flow falling from 1.03 +/- 0.08 at 100 beats/min to 0.83 +/0 0.06 at 250 beats/min (P < 0.01). This redistribution of blood flow away from the subendocardium was especially marked in the regions encompassing the papillary muscles and the intervening left ventricular lateral wall.
由于之前有观点认为肥厚心脏的心内膜下灌注可能不足，因此开展了本研究，以检测慢性左心室肥厚犬经壁心肌血流对起搏诱发心动过速的反应。通过在幼犬5 - 6周龄时结扎升主动脉产生心肌肥厚，与对照犬相比，相对左心室质量平均增加了87%。使用放射性核素标记的微球，在心室起搏心率为100、200和250次/分钟时检测心肌血流。两组犬在心率为100次/分钟时，每单位心肌质量的平均血流量相似，且两组动物在起搏过程中均有规律增加。心率增加并未改变正常犬心肌血流的经壁模式，但在左心室肥厚的动物中，以250次/分钟起搏时导致灌注从心内膜下显著重新分布，心内膜下/心外膜血流比值从100次/分钟时的1.03±0.08降至250次/分钟时的0.83±0.06（P<0.01）。这种血流从心内膜下的重新分布在包括乳头肌和其间左心室侧壁的区域尤为明显。
