Hsieh K S, Hu C T, Chang C K, Chang K C, Kuo T S, Chen H I
Department of Pediatrics, Veterans General Hospital-Kaohsiung, Taipei, Taiwan.
Proc Natl Sci Counc Repub China B. 1993 Oct;17(4):131-7.
Conventional methods to assess cardiac contractility have been focused on the mechanical properties of the myocardium. Many of these have suffered from theoretical and practical drawbacks. In this study, we have attempted to evaluate the left ventricular contractile status using the thermodynamic principle and compared these indices with the conventional index (dP/dt). A total of 8 mongrel dogs were anesthetized and artificially ventilated. A Millar catheter with high-fidelity multiple sensors was inserted into the aorta to record the simultaneous changes in aortic flow and pressure waves. Cardiac inotropy was increased by graded doses (2-32 micrograms/kg/min) of dobutamine. Angiotensin injection (100-300 micrograms) to achieve a blood pressure elevation of 30 mmHg was employed for afterload augmentation. Preload was increased by rapid infusion of 6% dextran solution (20 ml/kg). Several thermodynamic parameters were calculated at steady state during the control period and after drug interventions. These included power-averaged rate of power density generation (ARPD), peak ejection rate of change of power (PREP), energy-averaged power density (APD) and frequency-normalized ARPD (FARPD). PREP and APD were unchanged by afterload increment while FARPD, ARPD and dP/dt decreased significantly with an increase in afterload, ARPD was highly sensitive to an increased preload (p < 0.001), and PREP was also changed significantly by an increase in preload. dP/dt was boarderlinely affected by Dextran infusion (p = 0.05), and APD was independent of preload (P > 0.05). Inotropic stimulation increased ARPD, PREP, APD, FARPD and dP/dt by 139.0 +/- 48.0%, 98.0 +/- 51.4%, 74.0 +/- 49.7%, 60.0 +/- 30.4% and 44.6 +/- 10.4%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
评估心脏收缩力的传统方法一直聚焦于心肌的机械特性。其中许多方法存在理论和实际的缺陷。在本研究中，我们尝试运用热力学原理评估左心室收缩状态，并将这些指标与传统指标（dP/dt）进行比较。总共8只杂种犬被麻醉并进行人工通气。将带有高保真多传感器的Millar导管插入主动脉，以记录主动脉血流和压力波的同步变化。通过递增剂量（2 - 32微克/千克/分钟）的多巴酚丁胺增加心肌收缩力。注射血管紧张素（100 - 300微克）使血压升高30 mmHg以增加后负荷。通过快速输注6%右旋糖酐溶液（20毫升/千克）增加前负荷。在对照期和药物干预后，在稳态下计算了几个热力学参数。这些参数包括功率平均功率密度产生率（ARPD）、功率变化的峰值射血率（PREP）、能量平均功率密度（APD）和频率归一化ARPD（FARPD）。后负荷增加时，PREP和APD不变，而FARPD、ARPD和dP/dt随后负荷增加显著降低，ARPD对前负荷增加高度敏感（p < 0.001），前负荷增加也使PREP发生显著变化。右旋糖酐输注对dP/dt有临界影响（p = 0.05），APD与前负荷无关（P > 0.05）。变力刺激使ARPD、PREP、APD、FARPD和dP/dt分别增加了139.0 +/- 48.0%、98.0 +/- （摘要截断于250字） 51.4%、74.0 +/- 49.7%、60.0 +/- 30.4%和44.6 +/- 10.4%。
