麻醉开胸狗左室收缩末期压力直径关系及其对正变力因素的敏感性

LEFT VENTRICULAR END-SYSTOLIC PRESSURE-DIMENSION RELATION AND ITS SENSITILITY TO THE POSITIVE INOTROPIC FACTOR IN THE ANESTHETIZED OPEN-CHEST DOGS

心室收缩末期压力容积关系和压力直径关系(ESPVR和ESPDR),是评定心室收缩能力的较好指标。本工作记录13只麻醉开胸狗左室内压,并用超声晶体植入法记录左室前后径。将阻截下腔静脉回流(IVC)降低前负荷以及狭缩胸主动脉(AO)增加后负荷两种情况下所获得的一系列连续心跳的收缩末期压力(Pes)和直径(Des),经最小二乘法求得IVC和AO时的ESPDR。结果表明:(1) IVC或AO情况下获得的Pes与Des均高度线性相关(r值分别为0.9505±0.0578和0.9298±0.0581,P均<0.001);(2) 注入多巴酚丁胺(dob)后,IVC和AO时的ESPDR直径轴截距(Do)均无改变,斜率(E_(max))则明显增大,且IVC时的增加(174.4±23.5％)大于AO时(78.7±22.6％);(3) 对照和dob两种情况下,AO时ESPDR的D_0均小于IVC时。提示麻醉开胸狗左室ESPDR的斜率对变力状态的变化敏感,但其敏感性以及ESPDR的直径轴截距受获得ESPDR所采用的改变负荷的方式的影响,其原因可能是不同方式改变负荷时引起的Pes和Ves变动范围有所不同的缘故。

Left ventricular end-systolic pressure-dimension relation (ESPDR) was generated by the transient occlusion of the inferior vena cava (IVC) or thoracic aorta (AO) in 13 anesthetized open-chest dogs, while the left ventricular pressure was measured by a TP-200T pressure transducer and the anterior-posterior dimension was measured by a pair of ultrasonic crystal implanted in the endocardium and recorded by a Sonomicrometer.The results showed that: (1) the ESPDR was shown to be linear, unaltered by preload or afterload changes; (2) dobutamine produced a significant increase in the slope (Emax) of the ESPDR-IVC and ESPDR-AO relations, without remarkable effect on the dimension-axis intercept (Do). However, the change in Emax was more significant for ESPDR-IVC (174.43±23.48%, n=18), as compared with that for the ESPDR-AO (71.02±12.46%, n=12); (3) Do of the ESPDR-AO relation was smaller than that of the ESPDR-IVC both under control and during dobulamine infusion.We conclude that the linear ESPDR can be derived in the anesthetized openchest dogs either by caval occlusion or by aortic occlusion, and the slope appears to reflect left ventricular contractility. However, techniques used to generate the ESPDR may influence results, including the Do and the sensitivity of Emax to the inotropic state.