Changes in Cardiac Contractility in Burn Shock
Based on the evidence obtained from experiments on myocardial mechanics, some investigators1 have proposed taking the following indices as measures for the contractility of the intact heart, since these may be relatively less influenced by the factors before and after load on the heart: (1) the maximum rate of change in the left intraventricular pressure (expressed as dp/dt max.), (2) the ratio of dp/dt to the value of the instantaneous left intraventricular pressure (as (dp/dt)/p) and (3) the left intraventricular pressure-rate of pressure change loop (p-(dp/dt) loop, or simply ‘cardiac force loop’). These indices have been used widely in the investigation of hemonhagic, toxic as well as traumatic, shock2 and also in acute hypoxic tolerance of the heart3 to measure the condition of cardiac involvement. But in burn shock, most of the investigators evaluated the functional condition of the heart by determining the cardiac output and calculating the heart work4–6, and few of them approached this problem through direct measurement of the cardiac contractility on the basis of myocardial mechanics. In the work reported in this chapter, the cardiac contractility of dogs during the course of their Burn shock was estimated by measuring and calculating their first derivatives of the left intraventricular pressure, the velocity of shortening of the contractile elements of the myocardium (VCE) and the left intraventricular pressure — the rate of pressure change loop (p — (dp/dt) loop).
KeywordsMyocardial Contractility Cardiac Involvement Ventricular Pressure Cardiac Contractility Contractile Element
Unable to display preview. Download preview PDF.
- 2.Brückner, J. B. Kreislaufschock. pp. 275–84, 359-72. (Berlin, Heidelberg, New York: Springer)Google Scholar
- 3.Hu Xu-chu, Ning Xue-han etal. (1978). Studies on acute hypoxic tolerance of the heart. Acta Physiol., 30(1), 29–39. (In Chinese)Google Scholar
- 5.Fang Zhi-yang, Ge Sheng-de etal. (1979). Hemodynamics, hemorrheologic changes and disseminated intravascular coagulation at the shock stage in burned dogs. In The Treatment and Research in Burns. Proceedings of The National Burns Seminar. pp. 227–31. (In Chinese)Google Scholar
- 6.Yuan Shu-nan, Jiang Kun-yuan, Li Ao etal. Effects of some drugs on hemodynamics in severely burned patients at the early stage. Symposium on Burns. The Third Military Medical College of the PLA, Chongqing. pp. 178–88. (In Chinese)Google Scholar
- 7.Shtykhno, Y. M. and Markovskaya, G. I. (1973). Effect of thermal injury on the contractile function of rabbit heart. Patho-Physiol. Exp. Ther., 3, 64–6Google Scholar
- 8.Vornovitsky, E. G., Lenkova, N. A. and Vasilets, L. A. (1979). Changes in the contractile activity of the rabbit myocardium during burn shock. Bull. Exp. Biol. Med., 87 (1), 6–8Google Scholar
- 9.Andrew, G., Wallace, N., Skinner, S. Jr. and Mitchell, J. H. (1963). Hemodynamic determinants of the max. dp/dt of the left ventricular pressure. Am. J. Physiol., 205, 30–6Google Scholar