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首页> 外文期刊>Heart rhythm: the official journal of the Heart Rhythm Society >Cardiac output and vasodilation in the vasovagal response: An analysis of the classic papers
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Cardiac output and vasodilation in the vasovagal response: An analysis of the classic papers

机译：血管迷走神经反应中的心输出量和血管舒张作用：经典论文分析

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The simple faint is secondary to hypotension and bradycardia resulting in transient loss of consciousness. According to Ohm's law applied to the circulation, BP = SVR x CO, hypotension can result from a decrease in systemic vascular resistance (SVR), cardiac output (CO), or both. It is important to understand that when blood pressure (BP) is falling, SVR and CO do not change reciprocally as they do in the steady state. In 1932, Lewis, assuming that decreased SVR alone accounted for hypotension, defined "the vasovagal response" along pathophysiologic lines to denote the association of vasodilation with vagal-induced bradycardia in simple faint. Studies performed by Barcroft and Sharpey-Schafer between 1940 and 1950 used volume based plethysmography to demonstrate major forearm vasodilation during extreme hypotension and concluded that the main mechanism for hypotension was vasodilation. Plethysmographic measurements were intermittent and not frequent enough to capture rapid changes in blood flow during progressive hypotension. However, later investigations by Weissler, Murray, and Stevens performed between 1950 and 1970 used invasive beat-to-beat BP measurements and more frequent measurements of CO using the Fick principle. They demonstrated that CO significantly fell before syncope, and little vasodilation occurred until very late in the vasovagal reaction Thus, since the 1970s, decreasing cardiac output rather than vasodilation has been regarded as the principal mechanism for the hypotension of vasovagal syncope.
机译：单纯的晕厥是继发于低血压和心动过缓，导致短暂的意识丧失。根据应用于循环的欧姆定律BP = SVR x CO，低血压可能是由于全身血管阻力（SVR），心输出量（CO）或两者均降低引起的。重要的是要了解，当血压（BP）下降时，SVR和CO不会像在稳态下那样相互变化。 1932年，Lewis假定仅SVR下降是低血压的原因，他沿病理生理学定义了“血管迷走神经反应”，以表示血管舒张与迷走神经诱发的心动过缓之间的关联。 Barcroft和Sharpey-Schafer在1940至1950年之间进行的研究使用基于体积的体积描记法显示极端低血压期间主要的前臂血管舒张，并得出低血压的主要机制是血管舒张。脉搏波描记法测量是间歇性的，不够频繁，不足以捕获进行性低血压期间血流的快速变化。但是，后来由Weissler，Murray和Stevens进行的研究在1950年至1970年之间进行了使用有创搏动式BP测量，并使用Fick原理更频繁地测量了CO。他们证明CO在晕厥之前显着下降，直到血管迷走神经反应的很晚才发生血管舒张。因此，自1970年代以来，心输出量下降而非血管舒张一直被认为是血管迷走晕晕低血压的主要机制。

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