Influence of mild hypothermia on myocardial contractility and circulatory function

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• 作者：Jutta Weisser ; Jürgen Martin ; Egbert Bisping ; Lars S. Maier ; Friedhelm Beyersdorf ; Gerd Hasenfuss and Burkert Pieske
• 关键词：Key words Calcium – contractile function – heart failure – hemodynamics – ventricular function
• 刊名：Basic Research in Cardiology
• 出版年：2001
• 出版时间：March 2001
• 年：2001
• 卷：96
• 期：2
• 页码：198-205
• 全文大小：379 KB
• 刊物类别：Medicine
• 刊物主题：Medicine & Public Health
  Cardiology
  
• 出版者：Springer Berlin / Heidelberg
• ISSN：1435-1803

文摘

Myocardial contractility depends on temperature. We investigated the influence of mild hypothermia (37–31°) on isometric twitch force, sarcoplasmic reticulum (SR) Ca2+-content and intracellular Ca2+-transients in ventricular muscle strips from human and porcine myocardium, and on in vivo hemodynamic parameters in pigs. In vitro experiments: muscle strips from 5 nonfailing human and 8 pig hearts. Electrical stimulation (1 Hz), simultaneous recording of isometric force and rapid cooling contractures (RCCs) as an indicator of SR Ca2+-content, or intracellular Ca2+-transients (aequorin method). In vivo experiments: 8 pigs were monitored with Millar-Tip (left ventricular) and Swan-Ganz catheter (pulmonary artery). Hemodynamics parameters were assessed at baseline conditions (37°), and after stepwise cooling on cardiopulmonary bypass to 35, 33, and 31°C. Hypothermia increase isometric twitch force significantly by 91 ± 16% in human and by 50 ± 9% in pig myocardium (31 vs. 37°C; p < 0.05, respectively). RCCs or aequorin light emission did not change significantly. In anesthetized pigs, mild hypothermia resulted in an increase in hemodynamic paramters of myocardial contractility. While heart rate decreased from 111 ± 3 to 73 ± 1 min?1, cardiac output increased from 2.4 ± 0.1 to 3.1 ± 0.3 l/min, and stroke volume increased from 21 ± 1 to 41 ± 3 ml. +dP/dt_max increased by 25 ± 8% (37 vs. 31°C; p < 0.05 for all values). Systemic and pulmonary vascular resistance did not change significantly during cooling. Mild hypothermia exerts significant positive inotropic effects in human and porcine myocardium without increasing intracellular Ca2+-transients or SR Ca2+-content. These effects translate into improved hemodynamics parameters of left ventricular function.