Key result
Muscle nerve sympathetic activity bursts correlated closely with pulsative blood pressure changes and were initiated during heart beats with low diastolic pressure in subjects with cardiac arrhythmias.
Observational (n=11)
The study provides quantitative evidence of strong baro-reflex control of the vascular bed of skeletal muscle in humans during various cardiac arrhythmias.
Offers mechanistic insight into sympathetic control during arrhythmias; leaves open whether modulating baroreflex activity affects clinical outcomes.
Microelectrode recordings of multiunit muscle nerve sympathetic activity (MSA) and intra-arterial blood pressure were made in 11 subjects with different types of cardiac arrhythmias, including sinus arrhythmia, A-V block, extrasystolic beats, and atrial fibrillation. The MSA appeared in pulse-synchronous bursts, which, after compensation for a short reflex delay, correlated closely with the pulsative blood pressure changes. The sympathetic bursts always corresponded to diastoles and were usually initiated during heart beats with low diastolic pressure. The correlation between the diastolic pressure and the percentage occurrence of the bursts was found to be described by an inverse S-shaped curve, which became approximately linear after probit transformation. The results confirm previous findings indicating strong baro-reflex control of the vascular bed of skeletal muscle and provide a method for quantitative studies of these control mechanisms in man.
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Wallin et al. (1974) conducted an observational in Cardiac arrhythmias (n=11). Microelectrode recordings of muscle nerve sympathetic activity and intra-arterial blood pressure was evaluated on Correlation between diastolic pressure and percentage occurrence of sympathetic bursts. Muscle nerve sympathetic activity bursts correlated closely with pulsative blood pressure changes and were initiated during heart beats with low diastolic pressure in subjects with cardiac arrhythmias.