Pause-Dependent Paroxysmal Episode of Third-Degree Atrioventricular Block Triggered by Premature Atrial Contraction

BACKGROUND Paroxysmal third-degree atrioventricular block (AVB) can exhibit a vast array of symptoms, but commonly, paroxysmal AVB leads to presyncope, syncope, or possibly sudden cardiac death. We present a rare case of pause-dependent paroxysmal AVB that was triggered by a premature atrial contraction. CASE REPORT A 65-year-old man with frequent episodes of presyncope and syncope for 3 weeks was admitted to our hospital for further diagnosis. A resting 12-lead electrocardiogram showed an incomplete right bundle branch block, and a 24-h Holter recording showed multiple episodes of third-degree AVB. Intracardiac tracing revealed that the block site was distal, at the infra-His-Purkinje system. CONCLUSIONS This case highlights a rare case of pause-dependent paroxysmal AVB that was triggered by a premature atrial contraction. This type of AVB is an abrupt, unexpected, repetitive block of atrial impulses as they propagate to the ventricles. It is relatively rare, and due to its transient nature, it is often under recognized and can lead to sudden cardiac death.

Direct Oral Anticoagulants for Stroke Prevention in Patients With Device-Detected Atrial Fibrillation: A Study-Level Meta-Analysis of the NOAH-AFNET 6 and ARTESiA Trials

BACKGROUND

Device-detected atrial fibrillation (also known as subclinical atrial fibrillation or atrial high-rate episodes) is a common finding in patients with an implanted cardiac rhythm device and is associated with an increased risk of ischemic stroke. Whether oral anticoagulation is effective and safe in this patient population is unclear.

METHODS

We performed a systematic review of MEDLINE and Embase for randomized trials comparing oral anticoagulation with antiplatelet or no antithrombotic therapy in adults with device-detected atrial fibrillation recorded by a pacemaker, implantable cardioverter defibrillator, cardiac resynchronization therapy device, or implanted cardiac monitor. We used random-effects models for meta-analysis and rated the quality of evidence using the Grading of Recommendations Assessment, Development and Evaluation framework (GRADE). The review was preregistered (PROSPERO CRD42023463212).

RESULTS

From 785 citations, we identified 2 randomized trials with relevant clinical outcome data: NOAH-AFNET 6 (Non-Vitamin K Antagonist Oral Anticoagulants in Patients With Atrial High Rate Episodes; 2536 participants) evaluated edoxaban, and ARTESiA (Apixaban for the Reduction of Thrombo-Embolism in Patients With Device-Detected Sub-Clinical Atrial Fibrillation; 4012 participants) evaluated apixaban. Meta-analysis demonstrated that oral anticoagulation with these agents reduced ischemic stroke (relative risk [RR], 0.68 [95% CI, 0.50-0.92]; high-quality evidence). The results from the 2 trials were consistent (I2 statistic for heterogeneity=0%). Oral anticoagulation also reduced a composite of cardiovascular death, all-cause stroke, peripheral arterial embolism, myocardial infarction, or pulmonary embolism (RR, 0.85 [95% CI, 0.73-0.99]; I2=0%; moderate-quality evidence). There was no reduction in cardiovascular death (RR, 0.95 [95% CI, 0.76-1.17]; I2=0%; moderate-quality evidence) or all-cause mortality (RR, 1.08 [95% CI, 0.96-1.21]; I2=0%; moderate-quality evidence). Oral anticoagulation increased major bleeding (RR, 1.62 [95% CI, 1.05-2.50]; I²=61%; high-quality evidence).

CONCLUSIONS

The results of the NOAH-AFNET 6 and ARTESiA trials are consistent with each other. Meta-analysis of these 2 large randomized trials provides high-quality evidence that oral anticoagulation with edoxaban or apixaban reduces the risk of stroke in patients with device-detected atrial fibrillation and increases the risk of major bleeding.

Impact of Transjugular Intracardiac Echocardiography-Guided Self-Expandable Transcatheter Aortic Valve Implantation on Reduction of Conduction Disturbances

BACKGROUND

A high permanent pacemaker implantation (PPI) risk remains a concern of self-expandable transcatheter aortic valve implantation, despite the continued improvements in implantation methodology. We aimed to assess the impact of real-time direct visualization of the membranous septum using transjugular intracardiac echocardiography (ICE) during transcatheter aortic valve implantation on reducing the rates of conduction disturbances including the need for PPI.

METHODS

Consecutive patients treated with Evolut R and Evolut PRO/PRO+ from February 2017 to September 2022 were included in this study. We compared outcomes between the conventional implantation method using the 3-cusps view (3 cusps without ICE group), the recent method using cusp-overlap view (cusp overlap without ICE group), and our novel method using ICE (cusp overlap with ICE group).

RESULTS

Of the 446 patients eligible for analysis, 211 (47.3%) were categorized as the 3 cusps without ICE group, 129 (28.9%) were in the cusp overlap without ICE group, and 106 (23.8%) comprised the cusp overlap with ICE group. Compared with the 3 cusps without ICE group, the cusp overlap without ICE group had a smaller implantation depth (2.2 [interquartile range, 1.0-3.5] mm versus 4.3 [interquartile range, 3.3-5.4] mm; P<0.001) and lower 30-day PPI rates (7.0% versus 14.2%; P=0.035). Compared with the cusp overlap without ICE group, the cusp overlap with ICE group had lower 30-day PPI rates (0.9%; P=0.014), albeit with comparable implantation depths (1.9 [interquartile range, 0.9-2.9] mm; P=0.150). Multivariable analysis showed that our novel method using ICE with the cusp-overlap view was independently associated with a 30-day PPI rate reduction. There were no group differences in 30-day all-cause mortality (1.4% versus 1.6% versus 0%; P=0.608).

CONCLUSIONS

Our novel implantation method using transjugular ICE, which enable real-time direct visualization of the membranous septum, achieved a predictably high position of prostheses, resulting in a substantial reduction of conduction disturbances requiring PPI after transcatheter aortic valve implantation.

Transient 2:1 Atrioventricular Block with Peri-Conduction System Pacing After Leadless Pacemaker Implantation

This report discusses a case of transient 2:1 atrioventricular block with conduction system pacing 4 hours after leadless right ventricular pacemaker implantation in a 19-year-old patient with a history of cardioinhibitory syncope and asystole cardiac arrest but without preexisting atrioventricular block. The atrioventricular block was resolved spontaneously. Pacing morphology was suggestive of right bundle branch pacing. Neither 2:1 atrioventricular block nor conduction system pacing has previously been a reported outcome of right ventricular leadless pacemaker implantation. The report demonstrates that conduction system pacing with leadless devices is achievable. Further study of techniques, limitations, and complications related to intentional right ventricular leadless conduction system pacing is warranted.

His bundle pacing in nodal versus infranodal atrioventricular block: a mid-term follow-up study

INTRODUCTION

This study evaluated the feasibility of His bundle pacing (HBP) in consecutive, unselected patients with advanced atrioventricular block (AVB) over a medium-term follow-up period, comparing procedural characteristics between nodal and infranodal sites of the conduction block.

MATERIALS AND METHODS

Seventy-five consecutive patients with second-degree or third-degree AVB in which HBP was attempted were prospectively included in this study. The clinical and procedural-related characteristics of the patients were recorded at baseline and over a mid-term follow-up.

RESULTS

72% of the patients had normal QRS duration at baseline. Intracardiac electrograms revealed nodal AVB in 46 patients (61.3%). The permanent HBP procedural success was significantly higher in nodal AVB (84.8%) vs infranodal AVB (31%). There was no statistical difference between paced QRS duration, impedance, pacing and sensing thresholds and fluoroscopy time in the two groups. Infranodal block, baseline QRS duration, left bundle branch block morphology and ejection fraction were significantly associated with HBP procedural failure. The patients were followed for a period of 627.71±160.93 days. There were no significant differences in parameters at follow-up. An increase of >1 V in the His bundle (HB) capture threshold was encountered in one patient with infranodal AVB (11.1 %) and in four patients with nodal AVB (10.25%).

CONCLUSION

Permanent HBP is a feasible pacing technique in nodal AVB with a high success rate and stable thresholds in the medium term. Most infranodal blocks are located within the HB, so there is still the possibility to capture the conduction system, although with lower success rates.

Pacing induced cardiomyopathy: recognition and management

Right ventricle (RV) apex continues to remain as the standard pacing site in the ventricle due to ease of implantation, procedural safety and lack of convincing evidence of better clinical outcomes from non-apical pacing sites. Electrical dyssynchrony resulting in abnormal ventricular activation and mechanical dyssynchrony resulting in abnormal ventricular contraction during RV pacing can result in adverse LV remodelling predisposing some patients for recurrent heart failure (HF) hospitalisation, atrial arrhythmias and increased mortality. While there are significant variations in the definition of pacing induced cardiomyopathy (PIC), combining both echocardiographic and clinical features, the most acceptable definition for PIC would be left ventricular ejection fraction (LVEF) of <50%, absolute decline of LVEF by ≥10% and/or new-onset HF symptoms or atrial fibrillation (AF) after pacemaker implantation. Based on the definitions used, the prevalence of PIC varies between 6% and 25% with overall pooled prevalence of 12%. While most patients undergoing RV pacing do not develop PIC, male sex, chronic kidney disease, previous myocardial infarction, pre-existing AF, baseline LVEF, native QRS duration, RV pacing burden, and paced QRS duration are the factors associated with increased risk for PIC. While conduction system pacing (CSP) using His bundle pacing and left bundle branch pacing appear to reduce the risk for PIC compared with RV pacing, both biventricular pacing and CSP may be used to effectively reverse PIC.

Systematic review of the incidence and clinical risk predictors of atrial fibrillation and permanent pacemaker implantation for bradycardia in Fabry disease

INTRODUCTION

Fabry disease (FD) is an X-linked lysosomal storage disorder caused by enzyme deficiency, leading to glycosphingolipid accumulation. Cardiac accumulation triggers local tissue injury, electrical instability and arrhythmia. Bradyarrhythmia and atrial fibrillation (AF) incidence are reported in up to 16% and 13%, respectively.

OBJECTIVE

We conducted a systematic review evaluating AF burden and bradycardia requiring permanent pacemaker (PPM) implantation and report any predictive risk factors identified.

METHODS

We conducted a literature search on studies in adults with FD published from inception to July 2019. Study outcomes included AF or bradycardia requiring therapy. Databases included Embase, Medline, PubMed, Web of Science, CINAHL and Cochrane. The Risk of Bias Agreement tool for Non-Randomised Studies (RoBANS) was utilised to assess bias across key areas.

RESULTS

11 studies were included, eight providing data on AF incidence or PPM implantation. Weighted estimate of event rates for AF were 12.2% and 10% for PPM. Age was associated with AF (OR 1.05-1.20 per 1-year increase in age) and a risk factor for PPM implantation (composite OR 1.03). Left ventricular hypertrophy (LVH) was associated with AF and PPM implantation.

CONCLUSION

Evidence supporting AF and bradycardia requiring pacemaker implantation is limited to single-centre studies. Incidence is variable and choice of diagnostic modality plays a role in detection rate. Predictors for AF (age, LVH and atrial dilatation) and PPM (age, LVH and PR/QRS interval) were identified but strength of association was low. Incidence of AF and PPM implantation in FD are variably reported with arrhythmia burden likely much higher than previously thought.

PROSPERO DATABASE

CRD42019132045.

Modifiable risk factors for permanent pacemaker after transcatheter aortic valve implantation: CONDUCT registry

OBJECTIVE

The onset of new conduction abnormalities requiring permanent pacemaker implantation (PPI) after transcatheter aortic valve implantation (TAVI) is still a relevant adverse event. The main objective of this registry was to identify modifiable procedural risk factors for an improved outcome (lower rate of PPI) after TAVI in patients at high risk of PPI.

METHODS

Patients from four European centres receiving a balloon-expandable TAVI (Edwards SAPIEN 3/3 Ultra) and considered at high risk of PPI (pre-existing conduction disturbance, heavily calcified left ventricular outflow tract or short membranous septum) were prospectively enrolled into registry.

RESULTS

A total of 300 patients were included: 42 (14.0%) required PPI after TAVI and 258 (86.0%) did not. Patients with PPI had a longer intensive care unit plus intermediate care stay (65.7 vs 16.3 hours, p<0.001), general ward care stay (6.9 vs 5.3 days, p=0.004) and later discharge (8.6 vs 5.0 days, p<0.001). Of the baseline variables, only pre-existing right bundle branch block at baseline (OR 6.8, 95% CI 2.5 to 18.1) was significantly associated with PPI in the multivariable analysis. Among procedure-related variables, oversizing had the highest impact on the rate of PPI: higher than manufacturer-recommended sizing, mean area oversizing as well as the use of the 29 mm valve (OR 3.4, 95% CI 1.4 to 8.5, p=0.008) all were significantly associated with PPI. Rates were higher with the SAPIEN 3 (16.1%) vs SAPIEN 3 Ultra (8.5%), although not statistically significant but potentially associated with valve sizing. Implantation depth and postdelivery balloon dilatation also tended to affect PPI rates but without a statistical significance.

CONCLUSION

Valve oversizing is a strong procedure-related risk factor for PPI following TAVI. The clinical impact of the valve type (SAPIEN 3), implantation depth, and postdelivery balloon dilatation did not reach significance and may reflect already refined procedures in the participating centres, giving attention to these avoidable risk factors.

TRIAL REGISTRATION NUMBER

NCT03497611.

Remote monitoring in patients with heart failure with cardiac implantable electronic devices: a systematic review and meta-analysis

BACKGROUND

Remote monitoring (RM) of cardiac implantable electronic devices (CIEDs) is now the standard of care, but whether the demonstrated benefits of RM translate into improvements in heart failure (HF) management is controversial. This systematic review addresses the role of RM in patients with HF with a CIED.

METHODS AND RESULTS

A systematic search of the literature for randomised clinical trials in patients with HF and a CIED assessing efficacy/effectiveness of RM was performed using MEDLINE, PubMed and Embase. Meta-analysis was performed on the effects of RM of CIEDs in patients with HF on mortality and readmissions. Effects on implantable cardiac defibrillator (ICD) therapy, healthcare costs and clinic presentations were also assessed.607 articles were identified and refined to 10 studies with a total of 6579 patients. Implementation of RM was not uniform with substantial variation in methodology across the studies. There was no reduction in mortality or hospital readmission rates, while ICD therapy findings were inconsistent. There was a reduction in patient-associated healthcare costs and reduction in healthcare presentations.

CONCLUSION

RM for patients with CIEDs and HF was not uniformly performed. As currently implemented, RM does not provide a benefit on overall mortality or the key metric of HF readmission. It does provide a reduction in healthcare costs and healthcare presentations.

PROSPERO REGISTRATION NUMBER

CRD42019129270.

Individualised left anterior oblique projection for lead implantation into interventricular septum

Objective

We sought to investigate whether it is possible to obtain individualised left anterior oblique (LAO) by preprocedural electrocardiographic parameters and, if so, whether these parameters can help to improve the success rate of right ventricular (RV) lead implantation into the interventricular septum.

Methods

In this observational study, we assessed the relationship between preoperative electrocardiographic parameters and the angle of the interventricular septum obtained using thoracic CT. The participants were divided into two groups: a retrospective derivation cohort to derive the optimal formula for the individual septum axis, and a prospective internal validation cohort to which we applied the optimal formula and implanted using the new method.

Results

In the retrospective derivation cohort (n=39), the mean angle of individualised LAO assessed by thoracic CT was 53.1°±8.9°, and the preoperative ECG QRS axis was strongly correlated with the interventricular septum axis (R²=0.490). LAO projection derived from the preoperative ECG QRS axis confirmed that the RV lead was placed in the interventricular septum during the pacemaker procedure in the prospective internal validation group (n=30). The success rate for placing the RV lead into the interventricular septum was significantly improved in the internal validation cohort (93% vs 64%, p<0.05). In addition, the N-terminal pro-brain natriuretic peptide level decreased significantly after surgery in the interventricular septal indwelling group.

Conclusions

Individualised LAO angle derived from the preoperative ECG QRS axis is a new useful and simple method for RV lead implantation into the interventricular septum.

Trial registration number

UMIN000045741.

Wireless Communication Between Paired Leadless Pacemakers for Dual-Chamber Synchrony

BACKGROUND

Leadless pacemakers (LPs) can mitigate conventional pacemaker complications related to the transvenous leads and subcutaneous pocket surrounding the pulse generator. Although single-chamber leadless pacing has been established, multichamber pacing requires wireless bidirectional communication across multiple LPs to maintain synchrony. This preclinical study demonstrates the chronic performance of implant-to-implant (i2i) communication that achieves synchronous, dual-chamber pacing with 2 LPs.

METHODS

The i2i communication modality employs subthreshold electrical signals conducted between implanted LPs through the blood and myocardial tissue on a beat-by-beat basis. Right atrial and right ventricular LPs were implanted in 9 ovine subjects. The i2i transmission performance was evaluated 13 weeks after implant.

RESULTS

Right atrial and right ventricular LPs were implanted successfully and without complication in 9 ovine subjects. A total of 8715±457 right atrial-to-right ventricular and right ventricular-to-right atrial transmissions were sent per hour, with a success rate of 99.2±0.9%. Of periods with i2i communication failure when DDD pacing was not possible, 97.3±1.8% were resolved within 6 s.

CONCLUSIONS

For the first time, synchronized, dual-chamber pacing has been demonstrated in a chronic preclinical feasibility study by 2 leadless pacemakers using beat-to-beat, wireless communication, achieving a success rate of 99.2%.

Cardiac Implantable Electronic Devices in Ebstein Anomaly: Management and Outcomes

BACKGROUND

Optimal management of cardiac implantable electronic devices (CIEDs) in patients with Ebstein anomaly during tricuspid valve (TV) surgery is unknown. Thus, we aimed to characterize CIED management/outcomes in patients with Ebstein anomaly undergoing TV surgery.

METHODS

Patients at the Mayo Clinic from 1987 to 2020 with Ebstein anomaly and CIED procedure were reviewed for procedural details, complications, echocardiogram, and lead parameters. Five-year cumulative incidence of CIED complications were estimated using the Kaplan-Meier method.

RESULTS

Ninety-three patients were included; 51 were female, and mean age was 40.7±17.5 years. A new CIED was implanted in 45 patients at the time of TV surgery with the majority receiving an epicardial (n=37) CIED. Among 34 patients who had preexisting CIED (11 epicardial, 23 transvenous) at time of TV surgery, 20 had a transvenous right ventricular lead managed by externalizing the lead to the TV (n=15) or extracting the transvenous lead with epicardial lead implantation (n=5). Fourteen patients underwent CIED implantation (4 epicardial, 10 transvenous) without concurrent surgery. Placement of lead across the TV was avoided in 85% of patients. The 5-year cumulative incidence of CIED complications was 24% with no significant difference between epicardial and transvenous CIEDs (26% versus 23%, P=0.96). Performance of lead parameters was similar in epicardial and transvenous leads during median (interquartile range) follow-up of 44.5 (61.1) months.

CONCLUSIONS

In patients with Ebstein anomaly undergoing TV surgery, the use of epicardial leads and externalization of transvenous leads to the TV can avoid lead placement across the valve leaflets. Lead performance and CIED complications was similar between epicardial and transvenous CIEDs.

History and evolution of pacing and devices

Cardiac implanted electronic devices are commonplace in the modern practice of cardiology. This article reviews the history of the development of these technologies, with particular reference to the role played by UK physicians and members of the British Cardiovascular Society. Key breakthroughs in the treatment of heart block, ventricular arrhythmia and heart failure are presented in their historical and contemporary context so that the reader might look back on the incredible progress and achievements of the last 100 years and also look forward to what may be achieved in the coming decades.

Familial risk of atrioventricular block in first-degree relatives

Objective

Rare cases of genetically inherited atrioventricular block (AVB) have been reported; however, the heredity of AVB remains unknown. We aimed to assess the heredity of AVB.

Design, setting and participants

Using data from the Danish Civil Registration Registry, we established a nationwide cohort of individuals with parental links. Data were merged with information from the Danish Pacemaker and Implantable Cardioverter Defibrillator Registry, containing information on all pacemaker implantations performed in Denmark during the study period, to identify patients who received a first-time pacemaker because of AVB.

Results

A total of 4 648 204 individuals had parental links and a total of 26 880 consecutive patients received a first-time pacemaker due to AVB. Overall, the adjusted rate ratio (RR) of pacemaker implantation due to AVB was 2.1 (95% CI 1.8 to 2.5) if a father, mother or sibling had AVB compared with the risk in the general population. The adjusted RR was 2.2 (1.7–2.9) for offspring of mothers with AVB, 1.9 (1.5–2.4) for offspring of fathers with AVB and 3.5 (2.3–5.4) for siblings to a patient with AVB. The risk increased inversely proportionally with the age of the index case at the time of pacemaker implantation. The corresponding adjusted RRs were 15.8 (4.8–52.3) and 10.0 (3.3–30.4) if a mother or father, respectively, had a pacemaker implantation before 50 years.

Conclusion and relevance

First-degree relatives to a patient with AVB carry an increased risk of AVB with the risk being strongly inversely associated with the age of the index case at pacemaker implantation. These findings indicate a genetic component in the development of AVB in families with an early-onset disease.

Implementing Biological Pacemakers: Design Criteria for Successful

Each heartbeat that pumps blood throughout the body is initiated by an electrical impulse generated in the sinoatrial node (SAN). However, a number of disease conditions can hamper the ability of the SAN's pacemaker cells to generate consistent action potentials and maintain an orderly conduction path, leading to arrhythmias. For symptomatic patients, current treatments rely on implantation of an electronic pacing device. However, complications inherent to the indwelling hardware give pause to categorical use of device therapy for a subset of populations, including pediatric patients or those with temporary pacing needs. Cellular-based biological pacemakers, derived in vitro or in situ, could function as a therapeutic alternative to current electronic pacemakers. Understanding how biological pacemakers measure up to the SAN would facilitate defining and demonstrating its advantages over current treatments. In this review, we discuss recent approaches to creating biological pacemakers and delineate design criteria to guide future progress based on insights from basic biology of the SAN. We emphasize the need for long-term efficacy in vivo via maintenance of relevant proteins, source-sink balance, a niche reflective of the native SAN microenvironment, and chronotropic competence. With a focus on such criteria, combined with delivery methods tailored for disease indications, clinical implementation will be attainable.

Short-Term Outcomes of Transcatheter Versus Isolated Surgical Aortic Valve Replacement for Mediastinal Radiation-Associated Severe Aortic Stenosis

BACKGROUND

Surgical aortic valve replacement (SAVR) is associated with adverse outcomes in patients with radiation-associated aortic stenosis. Transcatheter aortic valve replacement (TAVR) may improve outcomes in this population.

METHODS

We evaluated 1668 TAVR and 2611 patients with SAVR enrolled in the Society of Thoracic Surgeons' database between 2011 and 2018. Multiple logistic regression was used to compare 30- day outcomes between TAVR and SAVR. Propensity-matched analysis was performed to confirm results of the overall cohort. Additionally, the cohort was stratified into early (2011-2014) versus contemporary (2015-2018) TAVR eras, and 30-day outcomes for TAVR and SAVR were compared. Finally, outcomes with transfemoral TAVR versus SAVR were compared.

RESULTS

In the overall cohort, TAVR was associated with significantly reduced 30-day mortality (odds ratio [OR]_TAVR/SAVR=0.60 [0.40-0.91]). Postoperative atrial fibrillation, pneumonia, pleural effusion, renal failure, and bleeding also occurred less frequently with TAVR. Stroke/transient ischemic attack (TIA; OR_TAVR/SAVR, 2.03 [1.09-3.77]) and pacemaker implantation (OR_TAVR/SAVR, 1.62 [1.21-2.17]) were higher with TAVR. Propensity-matched analysis yielded similar results as the overall cohort. Following stratification by era, TAVR versus SAVR was associated with reduced 30-day mortality in the contemporary but not early era (OR_Early, 0.78 [0.48-1.28]; OR_Contemporary, 0.31 [0.14-0.65]). Pacemaker implantation was higher with TAVR versus SAVR in both eras (OR_Early, 1.60 [1.03-2.46]; OR_Contemporary, 1.64 [1.10-2.45]). There was also a nonsignificant trend towards increased stroke/TIA with TAVR during both eras (OR_Early, 1.39 [0.58-3.36]; OR_Contemporary, 2.46 [0.99-6.10]). Finally, transfemoral TAVR (N=1369) versus SAVR revealed similar findings as the overall cohort; however, the association of TAVR with stroke/TIA was not statistically significant (OR_Stroke/TIA, 1.57 [0.79-3.09]).

CONCLUSIONS

TAVR provides an effective and evolving alternative to SAVR for radiation-associated severe aortic stenosis and was associated with lower 30-day mortality and postoperative complications. TAVR was associated with increased pacemaker implantation and a trend towards increased stroke/TIA. In this unique population with extensive valvular and vascular calcifications, the risk of stroke/TIA with TAVR requires careful consideration and further investigation.

Cardiac Implantable Electronic Device Interrogation at Forensic Autopsy: An Underestimated Resource?

BACKGROUND

Postmortem interrogations of cardiac implantable electronic devices (CIEDs), recommended at autopsy in suspected cases of sudden cardiac death, are rarely performed, and data on systematic postmortem CIED analysis in the forensic pathology are missing. The aim of the study was to determine whether nonselective postmortem CIED interrogations and data analysis are useful to the forensic pathologist to determine the cause, mechanism, and time of death and to detect potential CIED-related safety issues.

METHODS

From February 2012 to April 2017, all autopsy subjects in the department of forensic medicine at the University Hospital Charité who had a CIED underwent device removal and interrogation. Over the study period, 5368 autopsies were performed. One hundred fifty subjects had in total 151 CIEDs, including 109 pacemakers, 35 defibrillators, and 7 implantable loop recorders.

RESULTS

In 40 cases (26.7%) time of death and in 51 cases (34.0%) cause of death could not be determined by forensic autopsy. Of these, CIED interrogation facilitated the determination of time of death in 70.0% of the cases and clarified the cause of death in 60.8%. Device concerns were identified in 9 cases (6.0%), including 3 hardware, 4 programming, and 2 algorithm issues. One CIED was submitted to the manufacturer for a detailed technical analysis.

CONCLUSIONS

Our data demonstrate the necessity of systematic postmortem CIED interrogation in forensic medicine to determine the cause and timing of death more accurately. In addition, CIED analysis is an important tool to detect potential CIED-related safety issues.

Unconventional 2:1 Ventricular Pacing in a Neonate with Congenital Heart Block and Biventricular Noncompaction

Congenital complete heart block with concomitant biventricular noncompaction cardiomyopathy has been reported once previously. Although not universal, when restrictive physiology is present, impaired diastolic filling may pose a distinct challenge to pacing during the neonatal period. We present the case of a neonate with congenital complete heart block and biventricular noncompaction that resulted in severe diastolic dysfunction and atrioventricular dyssynchrony. We intentionally used 2:1 ventricular pacing to provide atrioventricular synchrony with every paced beat, and this resulted in hemodynamic and clinical improvement. This unconventional pacing technique may be beneficial in other neonates who have complete heart block and diastolic dysfunction.

Leadless Cardiac Pacemakers: The Next Evolution in Pacemaker Technology

Implantable pacemakers stand as a mainstay in our therapeutic arsenal, affording those suffering from advanced cardiac conduction system disease both an improved quality of life and reduced mortality. Annually, over 225,000 new pacemakers are implanted in the United States for bradyarrhythmias and heart block. The first implantable transvenous pacemakers appeared in 1965; they were bulky devices, hobbled by a short battery life, and a single pacing mode. Modern transvenous pacemakers have evolved considerably with significant improvements in battery life, pacing options, and lead technology but are still subject to a spectrum of complications stemming from either the subcutaneous pocket or the leads, including: hematoma, infection, wound dehiscence, pneumothorax, cardiac tamponade, lead dislodgment, upper extremity deep vein thrombosis, lead failure, venous obstruction, tricuspid valve insufficiency, and endocarditis. Single-chamber right ventricular (RV) leadless cardiac pacemakers, a concept from the past, has been revitalized to address these complications. Improvements in battery life, device miniaturization, catheter-based delivery tools, and advanced programming have made leadless cardiac pacemakers a viable option. In this review, we will discuss single-component leadless cardiac pacemaker technology, provide an overview of the two approved devices, and discuss their benefits as well as their limitations. [Full article available at http://rimed.org/rimedicaljournal-2017-11.asp].

Sinus Node and Atrial Arrhythmias

Although sinus node dysfunction (SND) and atrial arrhythmias frequently coexist and interact, the putative mechanism linking the 2 remain unclear. Although SND is accompanied by atrial myocardial structural changes in the right atrium, atrial fibrillation (AF) is a disease of variable interactions between left atrial triggers and substrate most commonly of left atrial origin. Significant advances have been made in our understanding of the genetic and pathophysiologic mechanism underlying the development and progression of SND and AF. Although some patients manifest SND as a result of electric remodeling induced by periods of AF, others develop progressive atrial structural remodeling that gives rise to both conditions together. The treatment strategy will thus vary according to the predominant disease phenotype. Although catheter ablation will benefit patients with predominantly AF and secondary SND, cardiac pacing may be the mainstay of therapy for patients with predominant fibrotic atrial cardiomyopathy. This contemporary review summarizes current knowledge on sinus node pathophysiology with the broader goal of yielding insights into the complex relationship between sinus node disease and atrial arrhythmias.

Association Between a Prolonged PR Interval and Outcomes of Cardiac Resynchronization Therapy: A Report From the National Cardiovascular Data Registry

BACKGROUND

A prolonged PR interval is common among cardiac resynchronization therapy (CRT) candidates; however, the association between PR interval and outcomes is unclear, and the data are conflicting.

METHODS

We conducted inverse probability weighted analyses of 26 451 CRT-eligible (ejection fraction ≤35, QRS ≥120 ms) patients from the National Cardiovascular Data Registry ICD Registry to assess the association between a prolonged PR interval (≥230 ms), receipt of CRT with defibrillator (CRT-D) versus implantable cardioverter defibrillator (ICD), and outcomes. We first tested the association between a prolonged PR interval and outcomes among patients stratified by device type. Next, we performed a comparative effectiveness analysis of CRT-D versus ICD among patients when stratified by PR interval. Using Medicare claims data, we followed up with patients up to 5 years for incident heart failure hospitalization or death.

RESULTS

Patients with a PR≥230 ms (15%; n=4035) were older and had more comorbidities, including coronary artery disease, atrial arrhythmias, diabetes mellitus, and chronic kidney disease. After risk adjustment, a PR≥230 ms (versus PR<230 ms) was associated with increased risk of heart failure hospitalization or death among CRT-D (hazard ratio, 1.23; 95% confidence interval, 1.14-1.31; P<0.001) but not ICD recipients (hazard ratio, 1.08; 95% confidence interval, 0.97-1.20; P=0.17) (P_interaction=0.043). CRT-D (versus ICD) was associated with lower rates of heart failure hospitalization or death among patients with PR<230 ms (hazard ratio, 0.79; 95% confidence interval, 0.73-0.85; P<0.001) but not PR≥230 ms (hazard ratio, 1.01; 95% confidence interval, 0.87-1.17; P=0.90) (P_interaction=0.0025).

CONCLUSIONS

A PR≥230 ms is associated with increased rates of heart failure hospitalization or death among CRT-D patients. The real-world comparative effectiveness of CRT-D (versus ICD) is significantly less among patients with a PR≥230 ms in comparison with patients with a PR<230 ms.

Effects of external electrical and magnetic fields on pacemakers and defibrillators: from engineering principles to clinical practice

The overall risk of clinically significant adverse events related to EMI in recipients of CIEDs is very low. Therefore, no special precautions are needed when household appliances are used. Environmental and industrial sources of EMI are relatively safe when the exposure time is limited and distance from the CIEDs is maximized. The risk of EMI-induced events is highest within the hospital environment. Physician awareness of the possible interactions and methods to minimize them is warranted.

Permanent pacemaker implantation after transcatheter aortic valve implantation: impact on late clinical outcomes and left ventricular function

BACKGROUND

Very few data exist on the clinical impact of permanent pacemaker implantation (PPI) after transcatheter aortic valve implantation. The objective of this study was to assess the impact of PPI after transcatheter aortic valve implantation on late outcomes in a large cohort of patients.

METHODS AND RESULTS

A total of 1556 consecutive patients without prior PPI undergoing transcatheter aortic valve implantation were included. Of them, 239 patients (15.4%) required a PPI within the first 30 days after transcatheter aortic valve implantation. At a mean follow-up of 22±17 months, no association was observed between the need for 30-day PPI and all-cause mortality (hazard ratio, 0.98; 95% confidence interval, 0.74-1.30; P=0.871), cardiovascular mortality (hazard ratio, 0.81; 95% confidence interval, 0.56-1.17; P=0.270), and all-cause mortality or rehospitalization for heart failure (hazard ratio, 1.00; 95% confidence interval, 0.77-1.30; P=0.980). A lower rate of unexpected (sudden or unknown) death was observed in patients with PPI (hazard ratio, 0.31; 95% confidence interval, 0.11-0.85; P=0.023). Patients with new PPI showed a poorer evolution of left ventricular ejection fraction over time (P=0.017), and new PPI was an independent predictor of left ventricular ejection fraction decrease at the 6- to 12-month follow-up (estimated coefficient, -2.26; 95% confidence interval, -4.07 to -0.44; P=0.013; R(2)=0.121).

CONCLUSIONS

The need for PPI was a frequent complication of transcatheter aortic valve implantation, but it was not associated with any increase in overall or cardiovascular death or rehospitalization for heart failure after a mean follow-up of ≈2 years. Indeed, 30-day PPI was a protective factor for the occurrence of unexpected (sudden or unknown) death. However, new PPI did have a negative effect on left ventricular function over time.

Left ventricular lead placement with over-the-wire technique for right ventricular pacing in a patient with distorted vessels

Vascular access can present a clinical challenge in the implantation of permanent pacemaker leads. We describe the case of an 81-year-old man with complete heart block in whom it was difficult to find a suitable vein for advancing a pacemaker lead. The left cephalic vein was selected for lead implantation; however, because of a 90° angle between the cephalic and axillary veins, the lead failed to advance. Because the patient was elderly and at high risk, we decided to place a left ventricular pacing lead in the right ventricle by means of an over-the-wire technique. After 1 month, the patient's pacing threshold was good, and the lead remained in the right ventricular apex. When patients have distorted vessels and lead placement seems difficult or impossible, we think that the over-the-wire placement technique can be effective.

Fistula from right internal mammary artery to superior vena cava after use of a laser sheath to extract a pacemaker lead

A 55-year-old woman presented with dyspnea on exertion due to a right internal mammary artery-to-superior vena cava arteriovenous fistula that occurred after pacemaker lead extraction with a laser sheath. The fistula was successfully repaired by placing a covered stent in the right internal mammary artery. In this unusual location, endovascular stenting is a reasonable alternative to coil embolization or surgical repair of an arteriovenous fistula resulting from laser lead extraction.

Pericardial tamponade and right-to-left shunt through patent foramen ovale after epicardial pacing-wire removal

After cardiac operations, careful management substantially reduces the risks of negative complications during or after the removal of temporary epicardial pacing wires. Herein, we report the case of a 58-year-old man who, 4 days after undergoing aortic root replacement, developed pericardial tamponade after the removal of temporary epicardial pacing wires. Consequent to the tamponade, a right-to-left shunt developed through a previously undiagnosed patent foramen ovale. The patient underwent emergency surgery to repair myocardium that had ruptured due to the removal of the wires, and he recovered uneventfully.

Severe obstructive sleep apnea syndrome with symptomatic daytime bradyarrhythmia

We report a case of severe obstructive sleep apnea (OSA) in a patient with symptomatic daytime cardiac bradyarrhythmia. Continuous positive airway pressure therapy prevented atrioventricular blocks that emerged after cardiac pacing for sick sinus syndrome. OSA could be associated with daytime bradyarrhythmia.

Cardiac resynchronization therapy in patients with heart failure: systematic review

CONTEXT AND OBJECTIVE

Cardiac resynchronization therapy (CRT) has emerged as the predominant electrical treatment strategy for patients on pharmacological therapy who present heart failure with wide QRS and low ejection fraction. The objective of this study was to investigate whether cardiac resynchronization therapy improved mortality and morbidity among patients with heart failure.

METHODS

This was a systematic review using the Cochrane Collaboration's methodology. The online search strategy included the Cochrane Library, Medline (Medical Literature Analysis and Retrieval System Online), Lilacs (Literatura Latino-Americana e do Caribe em Ciências da Saúde) and cardiology congresses from 1990 to 2006. The criteria for considering studies for this review were as follows:-types of studies: randomized controlled trials; types of interventions: cardiac resynchronization therapy compared with other therapies; types of participants: patients with heart failure with low ejection fraction and wide QRS; outcomes: death or hospitalization.

RESULTS

Seven trials met the selection criteria. The risk of death due to congestive heart failure was nonsignificant: relative risk (RR), 0.79; 95% confidence interval (CI): 0.60 to 1.03. There was an absolute risk reduction of 4% in all-cause mortality for the experimental group [RR 0.70; CI: 0.60 to 0.83; number needed to treat (NNT) 25]; sudden cardiac death showed a statistically significant difference favoring the experimental group, with absolute risk reduction of 1% (CI: 0.46 to 0.96; RR 0.67; NNT 100). There was an absolute risk reduction of 9% for hospitalization due to heart failure (RR 0.64; CI: 0.50 to 0.80; NNT 11) in the experimental group.

CONCLUSIONS

Patients receiving CRT had a significantly lower risk of hospitalization due to heart failure, but death rates due to heart failure were similar.

Transvenous biventricular pacing for cardiac resynchronization therapy in patients with persistent left superior vena cava and right superior vena cava atresia

Biventricular pacing for cardiac resynchronization therapy is an effective adjunctive therapy for the treatment of symptomatic moderate and severe congestive heart failure. However, experience with transvenous cardiac resynchronization therapy in patients who have both persistent left superior vena cava and right superior vena cava atresia is extremely limited. We successfully performed cardiac resynchronization therapy in 2 patients who had persistent left superior vena cava, right superior vena cava atresia, and congestive heart failure. Our 2 cases demonstrate the possibility of a total transvenous approach for left ventricular pacing despite the presence of serious cardiac venous anomalies. This approach enables clinicians to avoid the riskier epicardial lead placement, which requires a thoracotomy under general anesthesia.

Use of a transvenous dual-chamber ICD after a mustard operation for d-transposition of the great vessels

A 40-year-old man was admitted to our institution with mild heart failure symptoms, including palpitations and near syncope. Twenty-eight years earlier, he had undergone a Mustard operation to correct d-transposition of the great vessels. At the present admission, echocardiography revealed severe right (systemic) ventricular dysfunction. Continuous monitoring also showed sinus-node dysfunction, sinus bradycardia, and nonsustained ventricular tachycardia. The patient underwent successful transvenous placement of a dual-chamber implantable cardioverter-defibrillator for pacing of the atria and prevention of sudden cardiac death. To our knowledge, there have been no previous reports of transvenous placement of an implantable cardioverter-defibrillator after surgery for d-transposition of the great vessels in the English-language medical literature.

Transvenous right atrial and left ventricular pacing after the Fontan operation: long-term hemodynamic and electrophysiologic benefit of early atrioventricular resynchronization

We report a case of long-term, successful, endocardial atrioventricular pacing in a 32-year-old man who had severe heart failure and ascites after having undergone a Fontan procedure for tricuspid atresia 9 years earlier. The patient was referred to our hospital for Fontan revision. However, electroanatomic mapping of the right atrium revealed viable tissue at the interatrial septum above the os of the coronary sinus, and it appeared that the left ventricle could be paced from a coronary sinus branch. Therefore, instead of Fontan revision, an endocardial atrioventricular pacemaker was implanted transvenously. On 5-year follow-up, the patient remained in New York Heart Association functional class I and had not been readmitted to the hospital for congestive heart failure or arrhythmias. His atrial and ventricular leads continued to show excellent pacing and sensing results.

Pacemaker lead endocarditis caused by Achromobacter xylosoxidans

We report the case of a 35-yr-old patient who presented with high fever and chills. He had undergone a patch closure of the ventricular septal defect 18 yr before. One year later, a VVI pacemaker was implanted via the right subclavian vein because of complete heart block. Nine years after that, a new VVI pacemaker with another right ventricular electrode was inserted controlaterally and the old pacing lead was abandoned. Trans-thoracic and trans-esophageal echocardiogram identified the pacemaker lead in the right ventricle (RV) attaching hyperechoic materials and also a fluttering round hyperechoic mass with a stalk in the RV outflow tract. Cultures in blood and pus from pacemaker lead grew Achromobacter xylosoxidans. A diagnosis of pacemaker lead endocarditis due to Achromobacter xylosoxidans was made. In this regards, the best treatment is an immediate removal of the entire pacing system and antimicrobial therapy.

Pacemakers in children: medical and surgical aspects

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Indications and choices in pacemaker therapy

During their 33-year history of clinical use, cardiac pacemakers have evolved from devices primarily intended to save lives into complex systems designed to improve the cardiac patient's overall quality of life. To help physicians cope with this rapidly changing field, this review outlines current indications for pacemaker therapy and examines the wide range of options available. After describing the standard nomenclature for identifying the various systems, the author discusses pacemaker selection on the basis of cardiac rhythm alone, as well as rate-modulated therapy.

Implantation of a permanent pacemaker in a premature infant

In March 1984 we implanted a permanent, dual-chambered pacemaker in a 2.1-kg premature male infant suffering from congenital atrioventricular block, with an atrial rate of 170 beats per minute, a ventricular rate of 40 beats per minute, and ectopic ventricular escape beats. Through a left anterolateral thoracotomy, we implanted electrodes on the left atrium and left ventricle; through a second incision, in the left flank, we gained access to the retroperitoneal space by finger dissection. The electrodes were then guided through the diaphragmatic sulcus into the retroperitoneal space for attachment to a dual-chambered pacemaker permanently placed in the lumbar region. Our patient was discharged in good condition 23 days after operation and continues, despite some difficulties in establishing optimal pacemaker settings, to enjoy excellent clinical status 55 months after implantation, having moved progressively through pacemaker settings for VVI, DVI, and DDD modes, as his heart has improved. To our knowledge, this is the smallest and first-reported premature infant to be treated successfully for complete heart block with a permanent, physiologic pacemaker. In this surgical procedure, use of epicardial leads decreases the prospect of venous or intracardiac thrombosis; use of long leads situated partly in the chest and partly in the retroperitoneal cavity permits stretching as the child grows; and use of the relatively large peritoneal cavity for placement of the stimulator both protects the unit and permits unimpeded diaphragmatic movement, even in a very small infant. Implantation of this larger, permanent pacemaker, as an alternative to the usual ventricular-demand stimulating electrode, both avoids reoperation and permits flexibility in programming, to meet the changing needs of the growing patient.