• 作者： 謝凱生; 胡正濤; 張嘉侃; 張國柱; 郭德盛; 陳幸一
• 作者服務機構： 國防醫學院; 三軍總醫院及高雄榮總小兒科; 台灣大學電機工程研究所; 國防醫學院及慈濟醫學院醫學研究部
• 中文摘要： 傳統上評估左心室收縮力之變化多偏重於機械性之方法，這些方法都有許多理論上及實際上之缺陷。本研究乃嘗試用熱力學原理以評估左心室之收縮力狀態，並與傳統之左心室收縮期壓力最大斜率(dP/dt)比較，本研究以八隻雜種狗為實驗動物。經麻醉後，給予氣管插管後，插入8號Millar高傳真度導管以記錄主動脈血流及壓力之波形。並(1)以逐步增加之Dobutamine (2 ug/kg/min至32 ug/kg/min)劑量改變心臟之收縮力(2)Angiotensin靜脈注射(100-300ug)增加收縮壓30-50mmHg以增加心臟之後負荷(3)以30分鐘快速靜脈輸注6 % Dextran以增加心臟之前負荷。 在穩定基礎狀態下先記錄血流及壓波形，其後並在上述三項藥物注射之後再次分別記錄血流血壓波形，經由個人電腦程式分析測量下列指數：射血期功變化率最高值(PREP)，功密度產生平均功率(ARPD)，能量均化功密度(APD），頻率校正之 ARPD（FARPD）及dP/dt.增強心收縮力時，可使ARPD, PREP, APD，FARPD及dP/dt各增加139 ± 17%，98 ± 18%，74±18%，60.0±30.4%，及44.6±10.4 %。ARPD及FARPD均受到後負荷增加之影響。PREP稍受前負荷影響而APD不受其影響，而dP/dt受到明顯後負荷之影響，對前負荷則稍受其影響(p = 0.05)。本研究結果顯示4個熱力學指數均對收縮力之改變甚為敏感，其反應較傳統之dP/dt為靈敏，而對前後負荷增加有不等之變化，其中ARPD及FARPD均明顯受前後負荷之影響。PREP僅稍受前負荷影響，而APD均不受前後負荷之影響，故各熱力學心功能指數較傳統之dP/dt為優，其中以APD為各熱力學功能指數中最佳之收縮力評估指收數。
• 英文摘要： Conventional methods to assess cardiac contractility have been focused on the mechanical propertiesof 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 andcompared these indices with the conventional index (dP/dt). A total of 8 mongrel dogs were anesthetizedand artificially ventilated. A Millar catheter with high-fidelity multiple sensors was inserted into the aortato record the simultaneous changes in aortic flow and pressure waves. Cardiac inotropy was increasedby graded doses (2-32 ug/kg/min) of dobutamine. Angiotensin injection(100-300 ug) to achieve a bloodpressure elevation of 30 mmHg was employed for afterload augmentation. Preload was increased by rapidinfusion of 6% dextran solution (20 ml/kg). Several thermodynamic parameters were calculated at steadystate during the control period and after drug interventions. These included power-averaged rate of powerdensity 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 incre-ment while FARPD, ARPD and dP/dt decreased significantly with an increase in afterload, ARPD washighly sensitive to an increased preload (p＜0.001), and PREP was also changed significantly by an increasein preload. dP/dt was boarderlinely affected by Dextran infusion (p＝0.05), and APD was independent ofpreload (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. The results suggest thatthe four thermodynamic parameters are more sensitive to the contractile status than dP/dt. While onlyAPD and PREP are insensitive to afterload changes, ARPD and FARPD were obviously affected by pre-load change. APD appears to be the best thermodynamic parameter for the evaluation of left ventricularcontractility due to its load independence and higher sensitivity to inotropic stimulation. These thermo-dynamic indices generally appear better than conventional dP/dt.
• 中文關鍵字： contractility; preload; afterload; thermodynamic indices
• 英文關鍵字： --