Permanent cardiac pacing as primary therapy for neurocardiogenic (reflex) syncope

Abstract

Recurrent reflex (or neurocardiogenic) syncope is a common clinical problem. Pacemaker therapy has been advocated as a potential therapy in severe or drug refractory cases of reflex syncope, while others have suggested that it may provide a benefit if employed as a primary therapeutic modality. The following paper reviews the concepts behind pacemaker therapy for reflex syncope and the results of various clinical trials that have evaluated its potential utility as a primary therapeutic modality.

Closed‐looped stimulation cardiac pacing for recurrent vasovagal syncope: A systematic review and meta‐analysis

“…25 Rate drop algorithm is more complicated as it introduces rapid dual chamber pacing if the device detects a rapid reduction in heart rate. 8 Ammirati et al 27 suggested that dual chamber pacing with a rate-drop algorithm was more effective than dual chamber pacing with hysteresis algorithm. However, a recent study showed that the conventional pacemaker algorithm does not significantly reduce syncopal episodes 7 and the rate-only sensing algorithm of conventional pacemaker results in sensing the VVS process when it is well underway and provides the behind time pacing.…”

“…Hysteresis algorithm allows the pacing rate to surpass the lower limit of heart rate for a programmable period of time . Rate drop algorithm is more complicated as it introduces rapid dual chamber pacing if the device detects a rapid reduction in heart rate . Ammirati et al suggested that dual chamber pacing with a rate‐drop algorithm was more effective than dual chamber pacing with hysteresis algorithm.…”

“…Permanent DDI pacing with rate‐drop and rate hysteresis algorithm were reported to be effective in selected patients who presented with cardioinhibitory VVS . However, a recent study showed that the conventional pacemaker algorithm does not significantly reduce syncopal episodes and might act “too late” in the VVS process since patients develop decrease in blood pressure before bradycardia which is picked up by the conventional pacemaker …”

“…6 However, a recent study showed that the conventional pacemaker algorithm does not significantly reduce syncopal episodes 7 and might act "too late" in the VVS process since patients develop decrease in blood pressure before bradycardia which is picked up by the conventional pacemaker. 8 Closed-loop stimulation (CLS) is a pacemaker system with a developed impedance censor in the right ventricle which reflects contractility and responds with rapid atrioventricular pacing. CLS is a rate-adaptive pacing which detects increased myocardial contractility by measuring the right ventricular intracardiac impedance and activates a high-rate atrioventricular sequential pacing that may anticipate withdrawal of sympathetic tone and may counterbalance the increase in vagal tone.…”

Role of closed loop stimulation pacing (CLS) in vasovagal syncope

“…In patients with neurocardiogenic syncope, an increase in cardiac contractility may precede fall in blood pressure and heart rate, leading to syncope. 11,12 Conventional pacing systems can only detect changes in heart rate; thus it senses the occurrence of syncope only TA B L E 1 Classification of VVS based on response to HUTT…”