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Vagus nerve stimulation decreases left ventricular contractility in vivo in the human and pig heart
Author(s) -
Lewis M. E.,
AlKhalidi A. H.,
Bonser R. S.,
CluttonBrock T.,
Morton D.,
Paterson D.,
Townend J. N.,
Coote J. H.
Publication year - 2001
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.2001.00547.x
Subject(s) - vagus nerve stimulation , contractility , ventricle , vagus nerve , medicine , stimulation , heart rate , cardiology , anesthesia , esmolol , inotrope , blood pressure
1 Studies of the effect of vagus nerve stimulation on ventricular myocardial function in mammals are limited, particularly in the human. 2 The present study was designed to determine the effect of direct electrical stimulation of the left vagus nerve on left ventricular contractile state in hearts paced at 10 % above the natural rate, in anaesthetised pigs and anaesthetised human subjects undergoing open chest surgery for coronary artery bypass grafting. 3 Contractility of the left ventricle was determined from a series of pressure‐volume loops obtained from a combined pressure and conductance (volume) catheter placed in the left ventricle. From the measurements a regression slope of the end‐systolic pressure‐volume relationship was determined to give end‐systolic elastance (Ees), a load‐independent measure of contractility. 4 In six anaesthetised open chest pigs, stimulation of the peripheral cut end of the left cervical vagus nerve induced a significant decrease in Ees of 26 ± 14 %. 5 In nine patients electrical stimulation of the left thoracic vagus nerve close to its cardiac branch resulted in a significant drop in Ees of 38 ± 16 %. 6 The effects of vagal stimulation were blocked by the muscarinic antagonist glycopyrronium (5 mg kg −1 ). 7 Administration of the β‐adrenoreceptor antagonist esmolol (1 mg kg −1 ) also attenuated the effect of vagal stimulation, indicating a degree of interaction of vagal and sympathetic influences on contractility. 8 These studies show that in the human and pig heart the left vagus nerve can profoundly decrease the inotropic state of the left ventricular myocardium independent of its bradycardic effect.