Effect of Atrial Fibrillation and an Irregular Ventricular Response on Sympathetic Nerve Activity in Human Subjects

Abstract

Background— Although the hemodynamic changes associated with atrial fibrillation (AF) have been extensively studied, the neural changes remain unclear. We hypothesized that AF is associated with an increase in sympathetic nerve activity (SNA) and that the irregular ventricular response contributes to this state of sympathoexcitation. Methods and Results— In 8 patients referred for an electrophysiological study, SNA, blood pressure (BP), central venous pressure (CVP), and heart rate were recorded during 3 minutes of normal sinus rhythm (NSR) and 3 minutes of induced AF. In 5 of 8 patients who converted to NSR, right atrial (RA) pacing was performed for 3 minutes in atrial pacing triggered by ventricular sensing mode triggered by playback of an FM tape previously recorded from the right ventricle during AF (RA-irregular) and atrial pacing inhibited by atrial sensing mode at a rate equal to the mean heart rate obtained during AF (RA-regular). SNA data were expressed as percentage of baseline during NSR. SNA increased in all 8 patients during induced AF compared with NSR (171±40% versus 100%, respectively; P <0.01). This was associated with a trend for a decrease in BP and an increase in CVP ( P =0.02). Similarly, SNA was significantly higher during RA-irregular pacing compared with RA-regular pacing (124±24% versus 91±20%, respectively; P =0.03). BP and CVP were not significantly different between the 2 pacing modes. Conclusions— Induced AF results in a significant increase in SNA, which is in part attributable to the irregular ventricular response. Our findings suggest that restoring NSR or regularity might be beneficial, particularly in patients with heart failure.

Age-related regional differences in cardiac nerve growth factor expression

“…In parallel, NGF has been identified as a pro-survival factor for cardiomyocytes by developing anti-apoptotic effects via tyrosine kinase A (TrkA) receptor downstream signaling (Caporali et al 2008). With regard to its pivotal role in the integrity of cellular and subcellular systems, the autonomic nervous system has been further shown to be involved in heart rate, rhythm, and contractility (Wasmund et al 2003;Meyer et al 2010).…”

Restoring Sinus Rhythm Improves Baroreflex Function in Patients With Persistent Atrial Fibrillation

“…In the acute setting, we had previously shown that induced AF was associated with a 71% increase in sympathetic nerve activity (SNA) and that the variability in RR intervals played a major role in mediating the reflex sympathoexcitation 4. Interestingly, the increase in SNA was seen despite an increase in central venous pressure and absence of a significant decrease in BP, suggesting minimal contribution of the cardiopulmonary baroreflex and a presumed arterial baroreflex–mediated mechanism independent of mean BP.…”

“…On the one hand, changes in autonomic tone have been shown to play a major role in the genesis of AF 1, 2. On the other hand, AF has been shown to have an effect on autonomic function through its hemodynamic changes 3, 4. While several studies have suggested that patients with AF have impairment in the baroreflex, it is not clear whether these findings are the result of the associated comorbid conditions or the arrhythmia itself.…”

Hypertension and paroxysmal atrial fibrillation: a novel predictive role of high sensitivity C-reactive protein in cardioversion and long-term recurrence

“…However, any such conclusion regarding the aforementioned relations would be precarious, as AF with high ventricular response, observed commonly in PAF and in our study cohort, may significantly alter sympathetic nerve activity and thus affect blood pressure and heart rate levels. 39 Inflammation in atrial fibrillation due to hypertension I Rizos et al…”