Paul A. Gould

Outcome of advisory implantable cardioverter-defibrillator replacement: one-year follow-up.

BACKGROUND Implantable cardioverter defibrillator (ICD) generator advisories present management dilemmas for physicians regarding competing risks of ICD failure and replacement-related complications. There is currently a paucity of long-term data concerning the complications associated with advisory ICD replacement. OBJECTIVE In a large multicenter advisory ICD generator replacement cohort followed for 12 months, we aimed to assess replacement-related complications by performing a case-control determination of complication risk factors to identify characteristics that could assist with advisory ICD replacement decision making. METHODS Twelve large ICD implanting centers reviewed the 1-year follow-up outcome of advisory ICDs replaced between October 2004 and October 2005. The complication cohort was characterized and compared in a nested case-control analysis with age- and gender-matched controls without complications from the same replacement population. RESULTS At the 12 participating institutions, 451 of 2635 advisory ICD devices were replaced (17.1%). Over 355 +/- 204 days of follow-up, there were 41 (9.1%) complications; 27 (5.9%) required reoperation and included two deaths. There were 14 minor complications (3.1%). Multivariate analysis demonstrated that the number of previous pocket procedures was associated with an increase in complications and that combined consultant and fellow operators was associated with a decrease in complications compared with a single operator alone. CONCLUSIONS Complications from advisory ICD generator replacement are frequent and include infection and, rarely, death. The risk of replacement is increased in patients with multiple previous pocket procedures.

Evidence for increased atrial sympathetic innervation in persistent human atrial fibrillation

Objective: In this study, we aimed to compare the level of atrial sympathetic innervation in human atrial fibrillation (AF) to that in sinus rhythm (SR).

Progression of atrial remodeling in patients with high-burden atrial fibrillation: Implications for early ablative intervention.

BACKGROUND Advanced atrial remodeling predicts poor clinical outcomes in human atrial fibrillation (AF). OBJECTIVE The purpose of this study was to define the magnitude and predictors of change in left atrial (LA) structural remodeling over 12 months of AF. METHODS Thirty-eight patients with paroxysmal AF managed medically (group 1), 20 undergoing AF ablation (group 2), and 25 control patients with no AF history (group 3) prospectively underwent echocardiographic assessment of strain variables of LA reservoir function at baseline and at 4, 8, and 12 months. In addition, P-wave duration (Pmax,, Pmean) and dispersion (Pdis) were measured. AF burden was quantified by implanted recorders. Twenty patients undergoing ablation underwent electroanatomic mapping (mean 333 ± 40 points) for correlation with LA strain. RESULT Group 1 demonstrated significant deterioration in total LA strain (26.3% ± 1.2% to 21.7% ± 1.2%, P < .05) and increases in Pmax (132 ± 3 ms to 138 ± 3 ms, P < .05) and Pdis (37 ± 2 ms to 42 ± 2 ms, P < .05). AF burden ≥10% was specifically associated with decline in strain and with P-wave prolongation. Conversely, group 2 manifest improvement in total LA strain (21.3% ± 1.7% to 28.6% ± 1.7%, P <.05) and reductions in Pmax (136 ± 4 ms to 119 ± 4 ms, P < .05) and Pdis (47 ± 3 ms to 32 ± 3 ms, P < .05). Change was not significant in group 3. LA mean voltage (r = 0.71, P = .0005), percent low voltage electrograms (r = -0.59, P = .006), percent complex electrograms (r = -0.68, P = .0009), and LA activation time (r = -0.69, P = .001) correlated with total strain as a measure of LA reservoir function. CONCLUSION High-burden AF is associated with progressive LA structural remodeling. In contrast, AF ablation results in significant reverse remodeling. These data may have implications for timing of ablative intervention.

Characteristics of slow pathway conduction after successful AVNRT ablation

Background: AV node slow pathway conduction can persist following successful ablation for AV node reentrant tachycardia (AVNRT). We hypothesized that careful examination of AV nodal conduction curves before and after effective AVNRT ablation in patients with persistent slow pathway conduction could shed light on this apparent paradox.

Chronic atrial fibrillation does not influence the magnitude of sympathetic overactivity in patients with heart failure

AIMS In this study we sought to assess the influence of atrial fibrillation (AF) on sympathetic nervous system overactivity in congestive heart failure (CHF) patients. METHODS AND RESULTS We studied 133 consecutive patients with moderate to severe CHF. Subjects underwent haemodynamic assessment (right heart catheterization) and assessment of total systemic and cardiac sympathetic activity by the norepinephrine (NE) spillover method. The study population included 108 patients in sinus rhythm (SR) and 25 in AF. While AF patients had a lower cardiac output (CO) (SR vs AF: 4.2+/-0.1 vs 3.7+/-0.2l/min, P<0.05), the groups were otherwise matched for systemic blood pressure (BP), heart rate and filling pressures. In conjunction, total body NE spillover (SR vs AF: 5.8+/-0.4 vs 4.9+/-0.5 nmol/min, P>0.05) and cardiac NE spillover (SR vs AF: 339+/-21 vs 393+/-49 pmol/min, P>0.05) were not significantly different between the two groups, while the systemic clearance rate for NE was lower in the AF group (SR vs AF: 2.2+/-0.1 vs 1.6+/-0.1l/min, P<0.05). CONCLUSION Congestive heart failure patients in AF do not appear to have heightened sympathetic tone compared to CHF patients in SR.

Atrial Fibrillation Is Associated with Decreased Cardiac Sympathetic Response to Isometric Exercise in CHF in Comparison to Sinus Rhythm

Background: The presence of atrial fibrillation (AF) in congestive heart failure (CHF) is accompanied by increased mortality, although the exact mechanism is unclear. In previous studies, we have demonstrated cardiac baroreceptor abnormalities in association with AF and CHF. In this study, we sought to examine the effect of cardiac rhythm on the cardiac sympathetic response to exercise in CHF.

Investigating syncope: a review

Purpose of review This review focuses on recent literature on the cardiovascular investigation of syncope. Recent findings Syncope is a common and complex clinical entity with many varied etiologies, the diagnosis of which can often be elusive. Recent advances in the area of investigation in syncope include improvements in technologies for arrhythmia event monitoring and an increase in applicability and efficacy of traditional investigations. These advances have increased our ability to manage syncope. Summary A better understanding of the etiology of syncope in certain cohorts has allowed tailoring of investigations and management of syncope. This is evident when syncope occurs in the presence of structural heart disease, which is associated with a higher incidence of arrhythmias and an increased 1-year mortality. Patients with left-ventricular dysfunction should be considered candidates for an implantable cardioverter defibrillator based on heart function and syncopal presentation. In the absence of significant heart disease, investigations need to be tailored to diagnose neurally mediated causes for syncope and detection of intermittent bradycardia. The improved understanding of syncope has arisen from studies using improved investigational tools for syncope, in particular loop recorders, which are able to monitor cardiac rhythm over long periods. In those without structural heart disease and undifferentiated syncope, neurally mediated causes should be pursed initially. Tilt testing and loop recorders are employed most often in this cohort. Electrophysiological studies have largely been supplanted by implantable cardioverter defibrillator use in structural heart disease, with a low yield in patients with preserved heart function.

Seven years experience of a nurse-led elective cardioversion service in a tertiary referral centre: an observational study

BACKGROUND Traditionally the provision of elective external direct current cardioversion (EDCCV) for patients with atrial arrhythmias has been doctor-led. Increasing demands on hospital beds and time pressures for doctors has driven the desire for an alternative approach. We established a nurse-led cardioversion service in 2006 and present our experience. METHODS A prospective database of patients undergoing elective EDCCV between July 2006 and July 2013 was collected. Demographic data, arrhythmia, success and immediate complications of cardioversion were recorded. RESULTS A total of 974 EDCCV were performed on 772 patients. The mean patient age was 62.7 years, 564 (73.1%) were male. In 530 patients (69.0%) AF was the primary arrhythmia, in 242 (31.0%) atrial flutter. All EDCCVs were performed in a high dependency unit. Sinus rhythm was obtained in 692 patients (89.6%). Of 640 outpatients, 629 (98.3%) were discharged on the same day of their procedure. Eleven patients (1.7%) required admission to hospital. No patients required urgent temporary transvenous or permanent pacing, and there were no deaths in association with this procedure. CONCLUSIONS Nurse-led elective EDCCV is a safe and effective way of restoring sinus rhythm in patients with AF or atrial flutter, with additional benefits to resource provision.

Cardiovascular implantable electrophysiological device-related infections: a review.

Purpose of review The use of cardiac implantable electrophysiological device (CIED) therapy in the management of cardiac disease is increasing with the improvements in technology of permanent pacemaker and implantable cardioverter defibrillators. Accordingly CIED-related infections are increasing and have become an important clinical problem. The purpose of this review is to summarize current literature on the epidemiology, risk factors, pathophysiology, diagnosis and management of CIED-related infections. Recent findings The diagnosis and management of CIED-related infections can be difficult. Recent research would suggest extraction of all CIED components, and concomitant appropriate antibiotic therapy is the principal management modality of CIED component and pocket infection. The exact duration of antibiotic therapy and timing of re-implantation still require further delineation in the absence of comparative evidence; however, improvements in technologies such as the excimer laser have enabled percutaneous extraction to be performed effectively and safely in the vast majority of patients. Differentiating CIED-related infection from noninfected mechanical issues that may not require extraction or antibiotics can be very difficult. Research is continuing into better methods to diagnose and treat infection. Summary CIED-related infections are an important clinical problem with ongoing research to improve diagnosis and treatment. Currently, percutaneous CIED extraction and antibiotic therapy are the mainstay of treatment.

Characterization of Cardiac Brain Natriuretic Peptide Release in Patients With Paroxysmal Atrial Fibrillation Undergoing Left Atrial Ablation

Background—Paroxysmal atrial fibrillation (PAF) is associated with elevated levels of brain natriuretic peptide (BNP). The exact cardiac source and implications of this are currently unknown, as are the effects of left atrial ablation on cardiac BNP release. We sought to investigate BNP levels at different cardiac sites in PAF patients before and after left atrial ablation and compare these with a non–atrial fibrillation control cohort. Methods and Results—Twenty PAF patients (52±10 years, 70% men; left ventricular ejection fraction, 55±3%) undergoing ablation were studied, BNP levels were measured at different cardiac sites before and after ablation and compared with a control cohort undergoing ablation for left lateral accessory pathways (10 patients, 41±11 years; left ventricular ejection fraction, 55±4%). In both cohorts, the coronary sinus BNP levels were the greatest. The PAF cohort had significantly greater BNP levels than the control cohort at all sites before and after ablation. Ablation of the left atrium was associated with a significant decrease in coronary sinus BNP levels (P=0.05) and transcardiac BNP gradient (P=0.03). This was not observed in the control cohort. Conclusions—BNP levels are elevated in PAF, with the highest levels in the coronary sinus. Ablation of the left atrium was associated with an immediate decrease of BNP levels, implicating this as the source.