Clinical value of baroreflex sensitivity
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SPECIAL ARTICLE
Clinical value of baroreflex sensitivity M. T. La Rovere & G. D. Pinna & R. Maestri & P. Sleight
Published online: 27 November 2012 # Springer Media / Bohn Stafleu van Loghum 2012
Abstract The arterial baroreflex is an important determinant of the neural regulation of the cardiovascular system. It has been recognised that baroreflex-mediated sympathoexcitation contributes to the development and progression of many cardiovascular disorders. Accordingly, the quantitative estimation of the arterial baroreceptor-heart rate reflex (baroreflex sensitivity, BRS), has been regarded as a synthetic index of neural regulation at the sinus atrial node. The evaluation of BRS has been shown to provide clinical and prognostic information in a variety of cardiovascular diseases, including myocardial infarction and heart failure that are reviewed in the present article. Keywords Arterial baroreceptors . Baroreflex sensitivity . Autonomic nervous system . Prognosis . Myocardial infarction . Heart failure
Introduction While it was known by the early 1970s that hypertensive and cardiac patients had subnormal vagal baroreflex sensitivity M. T. La Rovere Department of Cardiology, Fondazione “Salvatore Maugeri”, IRCCS, Istituto Scientifico di Montescano, Montescano, Pavia, Italy G. D. Pinna : R. Maestri Department of Biomedical Engineering, Fondazione “Salvatore Maugeri”, IRCCS, Istituto Scientifico di Montescano, Montescano, Pavia, Italy P. Sleight Nuffield Department of Medicine, West Wing, level 6, John Radcliffe Hospital, Oxford OX3 9DU, UK M. T. La Rovere (*) Fondazione “Salvatore Maugeri”, IRCCS, Istituto Scientifico di Montescano, 27040, Montescano, Pavia, Italy e-mail: [email protected]
(BRS) [1, 2], the driving force for the clinical evaluation of BRS came from a series of experimental studies yielding important insights into the pathophysiological implications of baroreflex impairment related to heart disease. These studies showed a) that cardiac electrical stability can be affected by changes in autonomic flow [3, 4] and b) that baroreceptor reflexes can be modulated by cardiac afferent sympathetic activity activated by mechanical and chemical stimuli [5]. A major insight into the prognostic implication of BRS came from studies in an experimental preparation of sudden cardiac death [6]. In this model conscious dogs with a healed anterior myocardial infarction were submitted to a transient myocardial ischaemia produced during physiologically elevated sympathetic activity. It was found that the occurrence of ventricular fibrillation was much more frequent in the animals with depressed BRS and that the risk of developing ventricular fibrillation was inversely related to BRS. Importantly, the information provided by a depressed BRS was independent of left ventricular impairment [6]. Finally, it was also established that adequate baroreceptor activity was important for the response to the haemodynamic challenge of ventricular tachycardia [7].
Clinical value A wealth of clinical studies validated the ab
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