Mass H, Ali I, Velez W, Santiago O
Department of Physiology, Ponce School of Medicine, Puerto Rico 00732.
Ann N Y Acad Sci. 1992 Jun 16;653:206-10. doi: 10.1111/j.1749-6632.1992.tb19648.x.
To determine the hemodynamic responsiveness of dogs testing positive for heartworms (direct blood smear), we compared the response of control and heartworm-infected animals to stellate stimulation (SS). Using the anesthetized, open-chest model, twenty dogs (10 control and 10 heartworm-positive) were instrumented to measure left ventricular pressure (LVP), arterial pressure (AP), and coronary flow velocity (CFV) of the left circumflex coronary artery. CFV was converted to flow per gram tissue (CBFG) by weighing the perfusion area of the circumflex artery. The average wet weight of the worm mass infecting the dogs was 1.0 +/- 0.1 g, which represented an average of 5% of the right ventricular free wall weight. Overall heart size and right ventricular weights were greater in the heartworm-positive animals, as well as heart weight to body weight ratios. Prior to SS, LVP was the same for both groups. However, dP/dt and CBFG were 21% and 19% lower, respectively, in the heartworm-positive animals. Stellate stimulation sufficient to produce a 30-mmHg rise in AP led to 25%, 13%, and 40% increases in LVP, dP/dt, and CBFG, respectively, in the control animals. Increases of 22%, 10%, and 52% in the same parameters were observed in the heartworm-positive animals. Although control dP/dt and CBFG in the heartworm-positive animals were lower than in the heartworm-negative animals, heartworm infection at this level did not hinder myocardial responsiveness to SS.
为了确定经心丝虫检测呈阳性（直接血涂片）的犬的血流动力学反应性，我们比较了对照动物和感染心丝虫的动物对星状神经节刺激（SS）的反应。使用麻醉开胸模型，对20只犬（10只对照犬和10只心丝虫阳性犬）进行仪器安装，以测量左心室压力（LVP）、动脉压（AP）和左旋支冠状动脉的冠状动脉血流速度（CFV）。通过称量左旋支动脉的灌注面积，将CFV转换为每克组织的血流量（CBFG）。感染犬的心丝虫团块的平均湿重为1.0±0.1 g，占右心室游离壁重量的平均比例为5%。心丝虫阳性动物的总体心脏大小和右心室重量更大，心脏重量与体重的比值也更高。在进行星状神经节刺激之前，两组的左心室压力相同。然而，心丝虫阳性动物的dP/dt和CBFG分别低21%和19%。足以使动脉压升高30 mmHg的星状神经节刺激导致对照动物的左心室压力、dP/dt和CBFG分别增加25%、13%和40%。在心丝虫阳性动物中，相同参数分别增加了22%、10%和52%。尽管心丝虫阳性动物的对照dP/dt和CBFG低于心丝虫阴性动物，但这种程度的心丝虫感染并未妨碍心肌对星状神经节刺激的反应性。
