Pacing For Sinus Node Dysfunction Research Articles

Non-invasive and invasive autonomic tests to facilitate cardioneuroablation and complex indications for transcutaneous lead extraction and discontinuation of permanent pacing

Abstract Funding Acknowledgements Type of funding sources: None. OnBehalf Rare-A-Care registry Background Extracardiac vagal nerve stimulation (ECANS) and cardioneuroablation (CNA) are promising methods to cure vagally mediated bradycardia and validate indications for permanent pacing for sinus node dysfunction (SND), atrioventricular blocks (AVB), tachycardia-bradycardia syndrome (TBS) and cardio-inhibitory or mixed reflex syncope (VVS). There are limited information on clinical utility of those procedures in validation of indication for continuation of permanent pacing (PM) and transcutaneous lead extraction (TLE). Methods Data were collected from prospective multicentre registry of CNA facilitated by interdisciplinary consultations, state-of-art autonomic tests, atropine/propranolol tests, electrophysiologic study as well as ECANS. Share-decision making were used by EP-HEART-TEAM to developed patient-oriented therapy. Results Between June 2018-Jan 2021 the first 102 consecutive patients underwent interdisciplinary approach before invasive EPS and/or invasive ECANS, to consider biatrial, binodal CNA, if possible to cure functional bradycardia. Eleven (10%) patients had implanted permanent PM"s due to SND/AVB/TBS/CI-VVS and were considered for TLE. In 2 out of 11 cases CNA was not performed due to: 1) structural advanced 2nd and 3rd degree AVB with indication for TLE and permanent HBP (no.1), 2) incidental severely symptomatic persistent 3rd degree AVB more than 15 year ago without any further bradycardia episodes (only TLE, no.2). In further 9 of 11 cases with PM CNA was performed, however TLE was not attempted in 2 patients [(SND + PVC ablation + indication for beta-blocker therapy due to IHD in older male. TLE had not yet been attempted to confirm long-term success therapy by patient and/or physician (no.3); two periprocedural successful CNA resulted in disappearance of CI reflex however despite pacing syncopal events persist due to mixed etiology (no.4)]. In further 7/11 cases TLE-s were performed. Three cases had TLE prior to CNA [VVS-CI + advanced functional AVB - prior 3 pacemaker reimplantations and further "rescue" CNA, (no.5); CI-VVS + pacemaker infection (no.6); TLE of PM + TBS no.7]. Finally, in 4 cases TLE was recommended after CNA [CI-VVS (no.8, no.9 and no.10); mixed etiology: TBS + VVS-CI + intermittent, recurrent pericardial efffusion due to lead perforation, PM syndrome, (no. 11)]. Conclusions Interdisciplinary and comprehensive autonomic approach with ECANS and CNA enable EP-HEART-TEAM to offer patient-oriented therapy with a complex clinical scenarios before final decision about TLE and discontinuation of permanent pacing therapy.

Feasibility and safety of adenosine cardiovascular magnetic resonance in patients with MR conditional pacemaker systems at 1.5 Tesla.

BackgroundCardiovascular Magnetic Resonance (CMR) with adenosine stress is a valuable diagnostic tool in coronary artery disease (CAD). However, despite the development of MR conditional pacemakers CMR is not yet established in clinical routine for pacemaker patients with known or suspected CAD. A possible reason is that adenosine stress perfusion for ischemia detection in CMR has not been studied in patients with cardiac conduction disease requiring pacemaker therapy. Other than under resting conditions it is unclear whether MR safe pacing modes (paused pacing or asynchronous mode) can be applied safely because the effect of adenosine on heart rate is not precisely known in this entity of patients. We investigate for the first time feasibility and safety of adenosine stress CMR in pacemaker patients in clinical routine and evaluate a pacing protocol that considers heart rate changes under adenosine.MethodsWe retrospectively analyzed CMR scans of 24 consecutive patients with MR conditional pacemakers (mean age 72.1 ± 11.0 years) who underwent CMR in clinical routine for the evaluation of known or suspected CAD. MR protocol included cine imaging, adenosine stress perfusion and late gadolinium enhancement.ResultsPacemaker indications were sinus node dysfunction (n = 18) and second or third degree AV block (n = 6). Under a pacing protocol intended to avoid competitive pacing on the one hand and bradycardia due to AV block on the other no arrhythmia occurred. Pacemaker stimulation was paused to prevent competitive pacing in sinus node dysfunction with resting heart rate >45 bpm. Sympatho-excitatory effect of adenosine led to a significant acceleration of heart rate by 12.3 ± 8.3 bpm (p < 0.001), no bradycardia occurred. On the contrary in AV block heart rate remained constant; asynchronous pacing above resting heart rate did not interfere with intrinsic rhythm.ConclusionAdenosine stress CMR appears to be feasible and safe in patients with MR conditional pacemakers. Heart rate response to adenosine has to be considered for the choice of pacing modes during CMR.

Cardiac pacing in paediatric patients with congenital heart defects: transvenous or epicardial?

Cardiac pacing is a difficult technique in children, particularly in patients with congenital heart defects (CHDs). Few studies to date have addressed this topic. We performed a retrospective analysis of the results of a single centre. Between 1982 and 2008, 287 patients with CHD, median age of 5 years (25-75%, 1-11) underwent cardiac pacing for sinus node dysfunction (SND) and atrioventricular block (AVB); 97% of patients underwent at least one heart surgery. Endocardial systems (Endo) were implanted in 117 patients, epicardial systems (Epi) in 170, with 595 leads (228 Endo, 367 Epi). Endocardial systems showed a significantly older age group with more frequent SND; Epi a younger age group, with more frequent AVB, greater number of surgical interventions. Perioperative complications were mortality 0.6% (Epi), pericardial effusion 0.6% (Epi), and haemothorax 3.4% (Endo). The median follow-up is 5 (2-10) years: the pacing system failed in 29% of patients, 13% Endo, and 40% Epi (P < 0.0001). Multivariate analysis showed a significantly higher risk of failure for Epi, a lower implant age, greater the number of leads implanted. The risk of malfunction of the leads increases significantly for Epi and the younger age when implanted. The steroid-eluting leads have a lower risk of malfunction (P = 0.05), steroid-eluting Endo leads provide significantly better outcomes than Epi. Cardiac pacing in paediatric patients with CHD shows satisfactory results in the long term. Endocardial systems show significantly better results than Epi systems. A younger age when implanted is a risk factor for complications at follow-up.

Atrial-Based Pacing for Sinus Node Dysfunction in Dogs: Initial Results

An important consideration for the treatment of sick sinus syndrome (SSS) lies in the function of the atrioventricular (AV) node because most patients with SSS retain the ability to conduct atrial impulses. This retrospective study examined the feasibility of atrial pacing (AAI) in dogs with sinus node dysfunction (SND). Sixteen dogs with SND and AAI pacing were identified. Retrospective review of medical records. Follow-up time ranged from 45 to 1,227 days (mean: 292 days). Only 1 dog developed AV block 3 days postoperatively. Complete lead dislodgment occurred in 3/16 dogs 1, 19, and 27 days postoperatively. Lead perforation into the pericardial space occurred in 2/16 dogs. Rising thresholds for pacing with possible lead microdislodgment or fibrosis were suspected in another 3/16 dogs 57, 192, and 1,016 days after implantation. None of these dogs had complete loss of capture but all required higher thresholds for pacing. Based on this small group of dogs, clinically important AV block does not appear to occur in the long-term for dogs with SND. Risks of lead perforation, complete dislodgment, and rising thresholds for pacing, possibly because of microdislodgment, may be related to the initial skill level of the operator or the leads that were used. Use of leads with reduced torque at the lead tip, higher flexibility, increased lead-tip surface of contact with the endocardium or, more likely, use of alternate locations for pacing in the small right atrium of dogs with SND may decrease the frequency of these complications.

Outcome of patients aged over 75 years who received a pacemaker to treat sinus node dysfunction

The prognosis for patients aged over 75 years who receive a pacemaker in the context of sinus node dysfunction is unclear. We sought to evaluate the incidences of atrial fibrillation, heart failure and death in such patients, and the role of the pacing mode in their prognosis. This was a retrospective study of 102 patients aged over 75 years (mean 82.2 ± 4.4 years) who received a pacemaker in the context of sinus node dysfunction. During the follow-up period (mean 806 days), 36 patients (35.3%) experienced heart failure, 47 patients (46.1%) had an episode of paroxysmal atrial fibrillation, 19 patients (18.6%) progressed to chronic atrial fibrillation and 29 (28.4%) died, the fatal event being sudden death or of cardiac origin in almost half of these patients (44.8%). Patients assigned to dual-chamber minimal ventricular pacing showed significantly lower rates of heart failure episodes (P=0.023) and all-cause mortality (P<0.001) than those assigned to conventional dual-chamber pacing. In contrast, the two groups did not differ with regard to either paroxysmal or chronic atrial fibrillation. In patients aged over 75 years, the use of dual-chamber pacemakers incorporating an algorithm minimizing ventricular pacing for sinus node dysfunction seems to decrease the number of heart failure episodes and mortality. On the basis of this finding, the implantation of such devices seems justifiable, even in this age group.

Minimizing right ventricular pacing: A new paradigm for cardiac pacing in sinus node dysfunction

Sinus node dysfunction (SND) was first described as a clinical entity in 1968, although Wenckebach reported the electrocardiographic manifestation of SND in 1923. Sinus node dysfunction refers to a broad array of abnormalities in sinus node and atrial impulse formation and propagation. These include persistent sinus bradycardia and chronotropic incompetence without identifiable causes, paroxysmal or persistent sinus arrest with replacement by subsidiary escape rhythms in the atrioventricular (AV) junction or ventricular myocardium, and paroxysmal or persistent atrial fibrillation (AF). The frequent association of paroxysmal AF and sinus bradycardia or sinus inertia, which may oscillate suddenly from one to the other, usually accompanied by symptoms, is termed btachy-bradyQ syndrome. Sinus node dysfunction is primarily a disease of the elderly and is presumed to be due to senescence of the sinus node and atrial muscle. Collected data from 28 different studies on atrial-only (AAIR) pacing for SND showed a mean annual incidence of complete AV block (AVB) of 0.6% (0%-4.5%) with a total prevalence of 2.1% (0%-11.9%). This suggests that the degenerative process also affects the specialized conduction system, although the rate of progression is slow and does not dominate the clinical course of disease. Sinus node dysfunction is typically diagnosed in the sixth and seventh decade of life, which is also the average age at enrollment in clinical trials of pacemaker therapy for SND. Sinus node dysfunction may arise at any time in life as a secondary phenomenon of any condition that results in destruction of sinus node cells, such as ischemia, inflammation, or cardiac surgery. The clinical manifestations of SND are diverse, reflecting the range of typical sinoatrial rhythm disturbances. The most dramatic presentation is syncope. The mechanism of syncope is a sudden pause in sinus impulse formation, either spontaneously or after the termination of an atrial tachyarrhythmia, causing cerebral hypoperfusion. The pause in sinus node activity is

Right ventricular apical pacing: a necessary evil?

Clinical trial evidence suggests that traditional right ventricular apical pacing may be harmful. This review summarizes the existing evidence and outlines the major avenues of ongoing research in this field. Despite theoretical advantages of dual-chamber pacing, large randomized trials found only a small advantage over single-chamber ventricular pacing. Subsequent analysis of one of these trials suggested that this was due to the tendency for dual-chamber pacemakers to produce frequent, unnecessary right ventricular pacing. This hypothesis is supported by a prospective study among defibrillator recipients, showing that dual-chamber pacing results in a very high frequency of ventricular pacing and worse clinical outcomes, compared with backup ventricular pacing. These observations have led to a renewed interest in single-chamber atrial pacing for sinus node dysfunction, the development of new dual-chamber pacemaker algorithms designed to minimize right ventricular pacing, and the search for better ways to pace the ventricles in patients who require ventricular pacing. Conventional right ventricular apical pacing should be avoided whenever possible. In patients who require ventricular pacing, ongoing research will determine if selected-site pacing or multisite pacing improves clinical outcomes compared with traditional right ventricular apical pacing.

Heart Failure During Cardiac Pacing

Right ventricular apical (RVA) pacing creates abnormal left ventricular contraction, hypertrophy, and reduced pump function. The adverse effects of ventricular desynchronization may explain the association of RVA pacing with an increased risk of heart failure hospitalization (HFH) in clinical trials. Baseline and postimplantation variables were used to predict HFH in the Mode Selection Trial, a 2010-patient, 6-year trial of dual-chamber (DDDR) versus ventricular (VVIR) pacing in sinus node dysfunction. A Cox model showed that New York Heart Association (NYHA) class at baseline and follow-up predicted HFH (hazard ratio [HR], 3.99; 95% confidence interval [CI], 2.74-5.79 for NYHA class III/IV and HR, 2.17; 95% CI, 1.54-3.04 for NYHA class II versus class I); other predictors were heart failure (HR, 2.30; 95% CI, 1.70-3.11), atrioventricular (AV) block (HR, 1.48; 95% CI, 1.11-1.97), and myocardial infarction (MI)(HR, 1.37; 95% CI, 1.00-1.86). Postimplantation predictors were VVIR cumulative percent ventricular pacing (Cum%VP) >80 (HR, 3.58; 95% CI, 1.72-7.45), DDDR Cum%VP >40 or VVIR Cum%VP < or =80 (HR, 1.81; 95% CI, 0.94-3.50) versus DDDR Cum%VP < or =40; whether QRS duration (QRSd) was paced or spontaneous (HR, 2.21; 95% CI, 1.39-3.54; spontaneous versus paced); and drugs for atrial fibrillation (HR, 1.60; 95% CI, 1.19-2.15). Low baseline ejection fraction (EF) and postimplantation RVA-paced or spontaneous QRSd predicted HFH; the increased risk with QRSd was steeper for normal versus low EF (HR, 1.18; 95% CI, 1.11-1.27; versus HR, 1.08; 95% CI, 1.01-1.15; for a 10-ms increase); at a QRSd of approximately 200 ms, normal- and low-EF patients had equivalent risk. HFH risk nearly doubled when VVIR Cum%VP was < or =80 or DDDR Cum%VP was >40 versus DDDR Cum%VP < or =40 and was additive with other risk factors. Differences in HFH risk can be explained by interactions between substrate (atrial fibrillation, AV conduction, heart failure, MI, EF) and pacing promoters (ventricular desynchronization-paced QRSd and Cum%VP, and AV desynchronization-pacing mode). Management of RVA pacing is important for reducing the risk of HFH, particularly among patients with low EF and heart failure.

Pacing delivered rate and rhythm control for atrial fibrillation

Device therapy for atrial fibrillation remains contentious despite the recognized benefit of atrial pacing in sinus node dysfunction. There are various new specialized pacing algorithms that aim to provide rhythm or rate control in atrial fibrillation. We review the various options for device therapy and the evidence available concerning their effectiveness. Randomized trials on preventative algorithms for atrial fibrillation have not shown consistent benefit. Anti-tachycardia pacing for atrial fibrillation has inherent problems illustrated in this review and has failed to demonstrate objective improvement except in the case of atrial flutter. Several large randomized trials have demonstrated an adverse outcome with right ventricular apical pacing. These studies have shown an increase in atrial fibrillation with ventricular pacing. Recent studies have emphasised the importance of right ventricular apical pacing in burden of atrial fibrillation and therefore we discuss the likely confounding effect on previous trials and speculate on future directions. The use of a device with atrial fibrillation prevention algorithms in a patient with a bradycardia indication for pacing is not unreasonable but there is no hard evidence of benefit. Patients with sinus node dysfunction should be paced in the atrium alone. There is no indication for use of a device for atrial fibrillation without a conventional indication for pacing.

Association of Prolonged QRS Duration With Death in a Clinical Trial of Pacemaker Therapy for Sinus Node Dysfunction

Prolonged QRS duration (QRSd) is an important prognostic indicator for death and heart failure hospitalization in patients with systolic heart failure. The relationship of baseline QRSd to death and heart failure hospitalization in patients with sinus node dysfunction who require pacemaker therapy is unknown. Baseline QRSd from 12-lead ECGs before pacemaker implantation were analyzed in the Mode Selection Trial (MOST), a 6-year, 2010-patient randomized trial of dual-chamber versus ventricular pacing in sinus node dysfunction. Baseline QRSd was > or =120 ms in 23.4% of patients and was associated with older age, lower ejection fraction, cardiomyopathy, and prior heart failure. Adjusted Cox models demonstrated baseline QRSd > or =120 ms was a strong independent predictor of death (hazard ratio [95% CI] 1.35 [1.07, 1.70], P=0.010) but not heart failure hospitalization. The risk of death increased with increased QRSd from 60 to 120 ms (P=0.002 and hazard ratio [95% CI] 1.14 [1.05, 1.23] for 10-ms increase in this range) after adjustment for other death predictors. Baseline QRSd > or =120 ms was associated with increased risk of death during pacemaker therapy for sinus node dysfunction.

Baseline and post-implant risk scores for predicting heart failure hospitalization during pacemaker therapy for sinus node dysfunction

Background: Heart failure (HF) is an important endpoint in clinical trials of cardiac pacing for sinus node dysfunction (SND). We developed baseline and post-implant risk scores for predicting heart failure hospitalization (HFH) in the 1st year using MOST, a 2010 pt, 6-year randomized trial of DDDR versus VVIR pacing in SND.

Atrial septal pacing to prevent atrial fibrillation in patients with sinus node dysfunction: Results of a randomized controlled study

Background In order to assess the preventive effects of right atrial septal pacing on atrial fibrillation (AF) in patients with sinus node dysfunction, we conducted a prospective randomized controlled study in patients requiring atrial pacing. Methods The inclusion criterion was the presence of a sinus node dysfunction with or without episodes of AF. Pacing sites were randomized to either the right atrial septum or appendage. Patients with permanent AF or with atrioventricular (AV) block without sinus node dysfunction were excluded. Patients were discharged at a pacing rate of 65 beats per minute after setting of the optimal AV delay. The antiarrhythmic therapy remained unchanged until the first recurrence of AF. Sequential analyses were performed with the triangular test. Results Mean baseline characteristics were not different between the septum (n = 57) and the appendage (n = 67) groups. The triangular test evidenced a lack of effect of septal pacing at the last sequential analysis. The rates of AF-free survival were not different between the septum and the appendage group (65% vs 64%, P = .28). In the subgroup of patients with at least 1 episode of AF 3 months before pacing, AF-free survival was increased by atrial septal pacing (70% vs 40%, P = .018). The mean follow-up was 16 ± 13 months (range, 1–54). Conclusions Atrial septal pacing does not have a preventive effect on the occurrence of AF in patient requiring atrial pacing for sinus node dysfunction. Subgroup analysis suggests that atrial septal pacing may benefit patients with ≥1 episode of AF in the 3 months preceding pacing.

Adverse effect of ventricular pacing on heart failure and atrial fibrillation among patients with normal baseline QRS duration in a clinical trial of pacemaker therapy for sinus node dysfunction.

Dual-chamber (DDDR) pacing preserves AV synchrony and may reduce heart failure (HF) and atrial fibrillation (AF) compared with ventricular (VVIR) pacing in sinus node dysfunction (SND). However, DDDR pacing often results in prolonged QRS durations (QRSd) as the result of right ventricular stimulation, and ventricular desynchronization may result. The effect of pacing-induced ventricular desynchronization in patients with normal baseline QRSd is unknown. Baseline QRSd was obtained from 12-lead ECGs before pacemaker implantation in MOST, a 2010-patient, 6-year, randomized trial of DDDR versus VVIR pacing in SND. Cumulative percent ventricular paced (Cum%VP) was determined from stored pacemaker data. Baseline QRSd <120 ms was observed in 1339 patients (707 DDDR, 632 VVIR). Cum%VP was greater in DDDR versus VVIR (90% versus 58%, P=0.001). Cox models demonstrated that the time-dependent covariate Cum%VP was a strong predictor of HF hospitalization in DDDR (hazard ratio [HR], 2.99 [95% CI, 1.15 to 7.75] for Cum%VP >40%) and VVIR (HR 2.56 [95% CI, 1.48 to 4.43] for Cum%VP >80%). The risk of AF increased linearly with Cum%VP from 0% to 85% in both groups (DDDR, HR 1.36 [95% CI, 1.09, 1.69]; VVIR, HR 1.21 [95% CI 1.02, 1.43], for each 25% increase in Cum%VP). Model results were unaffected by adjustment for known baseline predictors of HF hospitalization and AF. Ventricular desynchronization imposed by ventricular pacing even when AV synchrony is preserved increases the risk of HF hospitalization and AF in SND with normal baseline QRSd.

Pacemaker mode selection: the evidence from randomized trials.

The evidence base for pacing, specifically with regards to outcome-based randomized trials, is only beginning to emerge. At present, the guidelines for pacing in sinus node dysfunction (SND), atrioventricular block (AVB), and vasovagal syncope are largely based on observational, not randomized studies. The findings from observational studies that physiological pacing was associated with reduced mortality, fewer strokes, less heart failure, and less AF when compared with ventricular pacing, were not uniformly supported by the early randomized trials of a relatively small sample size. Thus, it has become increasingly clear that large scale randomized trials are necessary to measure reliably the benefit, if any, of progressively more expensive and complex pacemakers. To provide reliable answers to these important questions, three large multicenter randomized trials in Canada, the United Kingdom, and the United States have been designed and conducted. The present review analyzed the results of completed randomized trials on pacemaker mode selection. To date, > 6,000 patients requiring permanent pacing to prevent bradycardia have been randomized; among these, dual chamber pacing did not prevent stroke or improve survival when compared with ventricular pacing. However, dual chamber pacing led to a moderate reduction of incident and chronic AF, reduced symptoms of heart failure in patients with SND, prevented pacemaker syndrome, and modestly improved quality-of-life. Further, a 5-10% reduction in mortality by atrial-based pacing cannot be excluded based on the results of the analyzed trials. The availability of data from ongoing randomized trials and their meta analysis should complete the totality of evidence during the next several years.

Which Type of Pacing for Sinus-Node Dysfunction?

For patients with sinus-node dysfunction, the advantages of dual-chamber pacemakers (maintaining atrioventricular synchrony and normal physiologic

Cardiac pacemakers in the transplanted heart: short term with the biatrial anastomosis and unnecessary with the bicaval anastomosis.

Sinus node dysfunction occurs commonly after orthotopic heart transplantation and may be caused by surgical trauma, ischemia to the sinus node, rejection, drug therapy and increasing donor age. In the past, using the standard biatrial technique described originally by Lower and Shumway, many series have reported permanent pacing in more than 10% of patients. Unlike sinus node dysfunction in nontransplanted patients, which typically worsens with time, sinus node dysfunction in the transplanted heart usually improves over a period of weeks to months. Delaying the implantation of a permanent pacemaker may render it unnecessary. The development of the bicaval technique for implantation of the donor heart appears to have decreased even further or even eliminated the need for early permanent pacing. Because sinus node dysfunction in the transplanted heart does not predict subsequent development of atrioventricular (AV) node dysfunction, rate-responsive atrial pacing should be used in the majority of cases. Even after appropriate pacing for sinus node dysfunction, the sinus node may recover and permanent pacing may be discontinued. AV conduction abnormalities are far less common and generally occur late after transplantation. Dual-chamber pacing is required and permanent pacing should be continued indefinitely.

Impact of internal audit on pacemaker prescription and the immediate costs of pacing in the northern region: towards implementation of the recommendations of the British Pacing and Electrophysiology Group.

In September 1990 a working party of the British Pacing and Electrophysiology Group recommended the routine use of physiological pacing systems in patients with bradycardia. An audit of the impact of these recommendations on pacemaker prescription in the Freeman Hospital between March 1990 and August 1991 has previously been reported. This paper considers the effect of that internal audit on subsequent pacemaker prescription from September 1991 to February 1993. The records of 1228 patients who underwent first pacemaker implantation at the Freeman Hospital between March 1990 and February 1993 were audited retrospectively. The patient's age, indication for pacing, pacing mode, and cost of the generator and leads were recorded. The indications for pacing were sinus node dysfunction (24.9%) (including patients with coexistent sinus node dysfunction and atrioventricular block), atrioventricular block (57.2%), atrioventricular block and atrial fibrillation (12.2%), and carotid sinus syndrome (5.7%). There was an increase in carotid sinus syndrome (2.7% to 8.1%) between the two study periods but no other differences in the distribution of case mix or characteristics of patients. The cost of the working party's recommended optimal pacing mode was calculated from multiplication of the mean cost of the recommended unit over the second half of the study period by the number of patients who would have received that unit. Between March 1990 and August 1991 atrial pacing for sinus node dysfunction (AAI, AAIR, DDD, or DDDR) increased by 138% (from 25.0% to 59.6%), mainly because of increased use of AAI mode. Physiological pacing for atrioventricular block (DDD or VVIR) increased by 41% (from 17.0% to 24.0%), and VVIR pacing for atrioventricular block with atrial fibrillation increased by 111% (from 10.5% to 22.2%). After the internal audit (that is, between September 1991 and February 1993), physiological pacing for atrioventricular block increased by a further 126% (from 24.0% to 54.2%). Sixty three per cent of this increase was in the first six months after the internal audit. Pacemaker prescriptions in sinus node dysfunction and atrioventricular block with atrial fibrillation were unchanged (59.6% physiological pacing for sinus node dysfunction and 22.2% v 27.3% VVIR pacing for atrioventricular block with atrial fibrillation). These changes in practice were accompanied by an increase in the age of patients receiving physiological units. Costs of pacemaker hardware for the final six months of the audit (excluding carotid sinus syndrome) increased by 38% over the costs that would have accrued had pacing policy remained the same as for the initial six month period before the circulation of the recommendations of the working party. Adoption of the guidelines of the working party in full would lead to a further 66% increase in the costs of hardware. The principal effect of the recommendations of the working party alone was increased use of AAI pacing for sinus node dysfunction, with little change in the costs of hardware. The internal audit was followed by an increase in physiological pacing for atrioventricular block, and this has had important financial consequences. Internal audit was followed by closer adherence to the recommendations of the working party.

Atrial permanent pacing for sinus node dysfunction with absent right superior vena cava

In patients with sinus node dysfunction and normal atrioventricular conduction, single chamber atrial pacing (AAI or AAIR mode) represents the most physiological treatment. Sinus node dysfunction is recognised in association with an absent right superior vena cava, and we present a case in which complete resolution of symptoms was achieved with endocardial atrial permanent pacing.