Pacemaker-mediated reentrant arrhythmia facilitated by an atrial-tracking leadless pacemaker.

INTRODUCTION: Pacemaker-mediated tachycardia is a known arrhythmia in patients with dual chamber pacemakers and defibrillators and intact ventriculoatrial (VA) conduction. We report a case of pacemaker-mediated reentrant arrhythmia (PMRA) in a patient with an atrioventricular (AV) synchronous leadless pacemaker. METHODS AND RESULTS: A 91-year-old female presented with 2:1 AV conduction and received an AV synchronous leadless pacemaker. She had atrial mechanical sense-ventricular paced beats between heart rates of 80-100 bpm more than 80% of the time. She was found to have a new cardiomyopathy and was referred for placement of biventricular pacemaker. At the time of device implantation, her electrocardiogram showed ventricular pacing with a short RP interval and superiorly directed P waves. Changes in the ventricular pacing rate resulted in changes in the atrial rate. Following device placement, her heart rate decreased to the lower rate limit of her pacemaker. The atrial mechanical sense impulse most likely was generated by a retrograde conducted P wave resulting in near incessant PMRA. CONCLUSION: PMRA may occur in patients who receive an AV synchronous leadless pacemaker with intact VA conduction and sinoatrial node dysfunction. Due to the lower rates of PMRA, this arrhythmia may be underrecognized. Interventions for and implications of PMRA need further investigation.

Complete pacemaker failure following lightning strike injury: A case report.

INTRODUCTION: Modern cardiovascular implantable electronic devices (CIEDs) have mechanisms that prevent damage from external electric shocks, and malfunction following accidental electrocution is rare. However, the effects of lightning injuries in patients with CIEDs are uncertain. CASE PRESENTATION: A 74-year-old man with a dual-chamber pacemaker due to complete heart block was struck by a lightning while farming. He had no serious injury at the time and sought medical evaluation 1 month later, when he presented with asymptomatic bradycardia. Device interrogation suggested major battery and lead damage, requiring extraction and subsequent placement of a new pacing system. DISCUSSION: While a previous report depicted pacing threshold elevation without extensive device impairment, our patient presented with major damage to the whole pacing system. The factors contributing to these divergent outcomes are unclear. Differences in injury mechanism, pacemaker model, and the pattern of electric current dispersion within the device may each play a part in this discrepancy.

Incidence of Fetal Arrhythmia Before and During the COVID-19 Pandemic: A Single-Center Experience.

Fetal arrhythmias are rare and carry significant morbidity and mortality without appropriate treatment. Initial reports exist of fetal arrhythmia in the setting of maternal COVID-19 infection. Our study sought to evaluate incidence of fetal arrhythmia before and during the COVID-19 pandemic at our institution. This retrospective cohort study from a tertiary care fetal cardiac center utilized the institutional REDCap database to search fetal arrhythmia diagnostic codes. Medical records of mother-fetus dyads were reviewed and data were collected on diagnoses, gestational age, treatment regimen, and postnatal outcomes. Patients were divided into pre-COVID and peri-COVID segments. 8368 total pregnancies were evaluated during the 7.3 years of study period. Forty-five patients (0.5%) had a significant fetal arrhythmia and were included in this study: 19 (42%) in the pre-COVID-19 group and 26 (58%) in the peri-COVID-19 group. No patients had associated congenital heart disease. There was a notable increase in the incidence of fetal supraventricular tachycardia (SVT) (1.82 per 1000 vs 2.65 per 1000 pregnancies) and complete heart block (1.04 per 1000 vs 1.77 per 1000 pregnancies) but no apparent change in other tachyarrhythmias during the COVID era. The proportion of antibody-mediated complete heart block increased from 50 to 87.5%. There was also an increase in the percentage of SVT patients requiring postnatal treatment during COVID-19 (53.8% vs 62.5%). Our experience shows an increased incidence of some fetal arrhythmia diagnoses during the COVID-19 pandemic. Additional multi-center studies will be necessary to fully evaluate the increased burden of fetal arrhythmias during the COVID-19 era as well as to elucidate etiology.

Oral Albuterol Treatment in Three Pediatric Patients with Bradycardia: A Novel Therapy.

Clinically significant bradycardia is an uncommon problem in children, but one that can cause significant morbidity and sometimes necessitates implantation of a pacemaker. The most common causes of bradycardia are complete heart block (CHB), which can be congenital or acquired, and sinus node dysfunction, which is rare in children with structurally normal hearts. Pacemaker is indicated as therapy for the majority of children with CHB, and while early mortality is lower in postnatally diagnosed CHB than in fetal CHB, it is still up to 16%. In young children, less invasive transvenous pacemaker systems can be technically challenging to place and carry a high risk of complications, often necessitating surgical epicardial pacemaker placement, which usually entails a median sternotomy. We report three cases of pediatric patients referred for pacemaker implantation for different types of bradycardia, treated at our institution with oral albuterol with therapeutic results that avoided the need for surgical pacemaker implantation at that time.

Transcatheter Closure of Perimembranous Ventricular Septal Defect Using KONAR-MF™: A Multicenter Experience.

Transcatheter closure of perimembranous ventricular septal defect (PmVSD) is an established procedure. However, the occurrence of complete heart block limits its scope. The newer KONAR-MF™ occluder has specific design characteristics that may improve the safety of PmVSD closure. The objective of the study was to describe the efficacy and mid-term follow-up of transcatheter closure of PmVSD using KONAR-MF™. The study was conducted prospectively in 3 Indian centers (January 2018-December 2022). PmVSD closure was done by both antegrade and retrograde methods, and patients were followed up at 1, 3, 6, 12 months, and annually after that. 121 out of 123 patients were included with the following characteristics: median age 4.4 (0.18-40) years; weight 15 (2.1-88) kg; mean Qp/Qs ratio 1.87 ± 0.52 and pulmonary artery mean pressure: 22 ± 6.9 mmHg. The procedure was successful in all but 3; the device was removed due to significant residual shunt (n = 2) and new development of aortic regurgitation (AR) (≥ mild) in 1. The median defect size was 5.2 (2.5-12) mm. Device sizes from 6/4 to 14/12 were deployed (median fluoroscopy time 13.3 min; range 3.6-47.8). Shunt occlusion rates were 90%-Immediate, 95%-pre-discharge, and 97%-1 month, with no instances of complete heart block after the procedure and during follow-up. Six had new onset AR (mild: 2, trivial 4), and one had increased tricuspid regurgitation. All patients were well during follow-up (median: 20 months; range: 6-46). The new KONAR-MF™ occluder appears to be a promising and safe alternative for the closure of the PmVSD; further long-term follow is merited.

A boy with fatigue and heart block: what's the mechanism?

When the atrioventricular node is damaged, accessory pathways can perform primary atrioventricular conduction but may spontaneously degrade during childhood. After surgical atrial septal defect repair during infancy, an adolescent male presented with fatigue due to iatrogenic complete atrioventricular node block with a degrading antegrade accessory pathway resulting in symptomatic bradyarrhythmia.

Three-dimensional electroanatomical mapping guided right bundle branch pacing in congenitally corrected transposition of great arteries.

AIMS: The ideal pacing strategy has been the Achilles' heel for patients with congenitally corrected transposition of great arteries (ccTGA) with bradycardia. Various pacing modalities were documented in the literature. This article describes a novel pacing strategy and its feasibility in ccTGA with an intact ventricular septum. METHODS AND RESULTS: We prospectively recruited three patients with ccTGA who presented with symptomatic complete heart block to our institute and were evaluated. All patients were planned for conduction system pacing. Those who had more than moderate or severe systemic atrioventricular regurgitation and systemic ventricular dysfunction were planned for conduction system pacing with an additional lead in the coronary sinus (CS) tributary, i.e. bundle branch pacing optimized cardiac resynchronization therapy with the intention to achieve incremental benefit. Since right bundle pacing is not described previously and in view of anatomical complexity in location, three-dimensional (3D) anatomical mapping was done with the EnSite system and later right bundle capture is identified conventionally as that of a left bundle in a normal heart. All three patients have stable lead positions and adequate thresholds at short-term follow-up. CONCLUSION: In this report, we demonstrated the feasibility of permanent physiological pacing of the systemic ventricle by capturing the right bundle with 3D anatomical mapping guidance, which results in physiological activation of the systemic ventricle.

Experience of treating congenital complete atrioventricular block with epicardial pacemaker in infants and young children: a retrospective study.

BACKGROUND: This article summarizes the treatment experience for congenital complete atrioventricular block (CCAVB) in newborns and infants, and discusses the necessity and feasibility of treating CCAVB with permanent pacemaker implantation in this population. METHODS: In this study, the clinical data and follow-up results of nine children admitted at our center with CCAVB from January 2005 to March 2023 were retrospectively analyzed. Among them, two children received early implantation of permanent pacemakers (within 1 year of age), two children received non-early implantation (1 year or older), and the remaining five children received no pacemaker implantation. CCAVB diagnosis was confirmed by clinical symptoms and clinical examinations, including electrocardiography and echocardiography before surgery. After surgery, the pacing and sensing functions of the pacemaker were observed using electrocardiography, echocardiography, and pacing threshold monitoring. A comprehensive assessment of the treatment efficacy was conducted, encompassing improvements in clinical symptoms, growth and development, as well as the absence of any additional potential complications. The children who did not receive pacemaker implantation were followed up. RESULTS: Among the four children who successfully received pacemaker implantation, one child who received non-early implantation died. For the remaining three children, the threshold level, amplitude, impedance, and minute ventilation sensor function of the pacemaker were good during the follow-up period, with a heart rate at the pacing rate. The growth and development of the aforementioned patients who received pacemaker implantation demonstrated adherence to the percentile curve, and their motor and cognitive development remained unaffected. However, among the children who did not undergo pacemaker implantation, two experienced death, while three were lost to follow-up, thereby limiting the evaluation of their long-term outcomes. CONCLUSIONS: Early implantation of an epicardial pacemaker at an early stage in newborns and infants diagnosed with CCAVB can significantly improve clinical symptoms without affecting their growth and development. These data are in line with current literature and suggest that early implantation of an epicardial pacemaker in newborns and infants diagnosed with CCAVB but further studies are needed.

Long-Term Follow-Up of Second-Degree Heart Block in Children.

Little is known about the outcomes of children with second-degree heart block. We aimed to determine whether children with structurally normal hearts and Mobitz 1, 2:1 block or Mobitz 2 are at increased risk for progressing to complete heart block (CHB) or requiring a pacemaker (PM) at long-term follow-up. We searched our institutional electrophysiology database for children with potentially concerning second-degree block on ambulatory rhythm monitoring between 2009 and 2021, defined as frequent episodes of Mobitz 1 or 2:1 block, episodes of Mobitz 1 or 2:1 block with additional evidence of conduction disease (i.e. first-degree heart block, bundle branch block), or episodes of Mobitz 2. Ambulatory rhythm monitor, ECG, and demographic data were reviewed. The primary composite outcome was CHB on follow-up rhythm monitor or PM placement. 20 patients were in the final analysis. Six (30%) patients either developed CHB but do not have a PM (4 = 20%) or have a PM (2 = 10%). Median follow-up was 5.8 years (IQR 4.4-7.0). Patients with CHB or PM were more likely to have second-degree block at maximum sinus rate (67% vs. 0%, p = 0.003), a below normal average heart rate (67% vs. 14%, p = 0.04), and 2:1 block on initial ECG (50% vs. 0%, p = 0.02). In this study of children with potentially concerning second-degree block, 30% of patients progressed to CHB or required a PM. Second-degree block at maximum sinus rate, a low average heart, and 2:1 block on initial ECG were associated with increased risk of disease progression.

Definitions and Pitfalls in the Diagnosis of Atrioventricular Block.

The widespread use of disparate definitions of atrioventricular block has created important diagnostic problems. Adherence to the correct definitions provides a logical and simple framework for clinical evaluation. This review focuses on the clinical importance of the definitions in the diagnosis of the various types of atrioventricular (AV) block and the associated diagnostic pitfalls.

Placement of permanent pacemaker in a low-birth-weight infant with congenital heart block: a case report.

One of the rare diseases with a high mortality rate in infants is congenital heart block (CHB) with neonatal lupus erythematosus (NLE) as the most common cause. A permanent pacemaker (PPM) is indicated for symptomatic bradycardia. The choice of PPM in the paediatric population is different from that in the adult population because of several reasons like small size, account of somatic growth, and difference in physiological changes. Here, we present a case in which a 2.6 kg and 45 days old baby with CHB secondary to NLE was successfully treated with a single-chambered adult-sized PPM with epicardial lead. According to our knowledge, this is the smallest baby in Pakistan in which PPM has been implanted.

Rate of various access sites for temporary transvenous pacing and different outcomes at Lady Reading Hospital, Peshawar Pakistan.

Objective: To evaluate the various temporary transvenous pacemaker (TPM) access sites, its indications, procedural complications, and outcomes of patients. Methods: This prospective study conducted in a tertiary care hospital of Peshawar, included 100 patients, who underwent TPM for any reasons, via the trans jugular, subclavian, or trans-femoral route. The duration of the study was from October 1st, 2021 to March 31st, 2022. The demographic, procedure -related complications, causes of complete heart block and in hospital outcomes were recorded. Results: Of the 100 patients who underwent temporary transvenous pacing, 56%were males and 44% were females, with an age range of 46-80 years. In majority of the patients, (N =54) internal jugular vein was used as the venous access site followed by the subclavian vein. (N=24). Coronary artery disease was prevalent in 42% of the patients. 50% had complete AV block, 19% had symptomatic second-degree block, and 10% had sinus nodal diseases. Seventy three percent of the patients needed TPM implantation on an emergency basis, which is statistically significant (p=0.009). Almost 40% of the patient ultimately underwent a permanent pacemaker. Out of 100 patients, 16 patients expired. The major procedure related complications were bleeding 16% overall at the puncture site and 14.8% in the internal jugular group. Other complications were local infection 13% at the insertion site followed by hemopericardium 3%, in the internal jugular group. Conclusion: Atrioventricular block is the commonest indication for temporary pacing in our study. The average time the TPM remained in place was significantly higher in the trans jugular approach group along with a higher complication rate in this group.

Cohort study of congenital complete heart block among preterm neonates: a single-center experience over a 15-year period.

Congenital complete heart block (CCHB) is a very rare condition, with high risk of mortality. Prematurity is associated with immaturity of the cardiovascular system. Morbidity related to CCHB and prematurity has never been described. We describe a tertiary perinatal center experience over a 15-year period on CCHB management and complications in preterm infants. This is a single-center observational cohort study. All neonates admitted to neonatal intensive care unit with a diagnosis of isolated CCHB between January 2006 and January 2021 were identified. All preterm neonates (< 37 weeks) were compared with a control cohort of term neonates (≥ 37 weeks). Antenatal data, complications of prematurity, medical, and surgical management of CCHB were recorded. Twenty-four neonates with isolated CCHB (16 preterm and 8 term) were born during the study period, including 5 very preterm (< 32 weeks) and 11 preterm (32 to 37 weeks). All very preterm were born via emergency caesarian section without antenatal steroid administration. They had multiple severe morbidities including chronic lung disease, necrotizing enterocolitis, grades 3-4 intraventricular hemorrhage, cystic periventricular leukomalacia, and longer periods of mechanical and non-invasive ventilatory support than preterm. Thirteen out of sixteen preterm infants had permanent pacemakers inserted, compared to 1/8 for term newborns. All babies born before 35-week gestation were either paced or died.Conclusion: Premature neonates with CCHB have high risk of mortality and morbidity especially if undiagnosed and born by unnecessary emergency caesarian section without antenatal steroids. Prematurity below 35 weeks may be associated with death or pacemaker insertion. This supports better antenatal screening to avoid induced prematurity. What is Known: • Congenital complete heart block is a very rare condition associated with high morbidity and mortality. • Antenatal risk factors for poor outcome include fetal hydrops, low ventricular rate (HR <55 beats per minute), and congenital heart defect. What is New: • Infants born <32 weeks with CCHB had no antenatal steroid administration, and sustained high burden of morbidity (chronic lung disease, intraventricular hemorrhage, and cystic periventricular leukomalacia). • Birth <35 weeks is strongly associated with requiring pacing prior to discharge or death.

Cardiogenic shock with complete heart block secondary to dengue myocarditis requiring temporary pacing.

This case illustrates acute myocarditis with complete heart block in a 13-year-old teenager as a rare complication of acute dengue illness. He required urgent temporary pacing with inotropic support and antifailure medications. Complete heart block in dengue myocarditis is an acute but reversible condition. A similar presentation in a dengue-endemic country or with a history of travelling to tropical countries warrants a suspicion of dengue infection.

Management of Complete Heart Block in a Pregnant Woman with Systemic Lupus Erythematosus-Associated Complications: Treatment Considerations and Pitfalls.

We present a case of a pregnant woman with systemic lupus erythematosus (SLE) who was diagnosed with asymptomatic complete heart block (CHB) during pregnancy. To evaluate possible risks and benefits of pacemaker (PM) implantation, a multidisciplinary counselling board was held. Its recommendation was to perform PM implantation to prevent intra-uterine growth restriction from insufficient cardiac output using a fluoroscopic protective shield. The procedure was performed without complications and established permanent pacing on onwards ECG examinations. The patient subsequently gave birth to a healthy newborn. After a retrospective clinical case evaluation and review of relevant literature, a presumptive association between CHB and the primary diagnosis was proposed. Above that, pregnant women with SLE who develop hypertension are commonly treated with methyldopa, which may cause conduction abnormalities. Clinical recommendations for young female patients expecting pregnancy are lacking in this area. Careful diagnostic and treatment approaches should be used in the management of possible SLE-related complications in women of child-bearing age, focusing on preventable events.

Complete interatrial block in a left-atrial dependent atrioventricular node.

INTRODUCTION: A middle-age woman underwent an electrophysiologic study due to recurrent atypical atrial flutter. METHODS AND RESULT: Radiofrequency ablation of cavotricuspid isthmus and anterior mitral line was performed. During energy delivery on the anterior left atrial wall, interatrial dissociation and complete block of the sinus impulse to the atrioventricular (AV) node was observed. AV node activation became dependent on a subsidiary left atrial rhythm. CONCLUSION: Anatomical location of intra and inter-atrial connections must be taken into account when performing extensive ablation procedures, specially in cases with prior cardiac surgeries.

Predicting complete heart block after alcohol septal ablation for hypertrophic cardiomyopathy using a risk stratification model and clinical tool.

BACKGROUND: Alcohol septal ablation (ASA) is a proven method of septal reduction for patients with drug refractory, symptomatic hypertrophic obstructive cardiomyopathy (HOCM). This procedure is associated with a 6.5-11% risk of complete heart block (CHB). OBJECTIVE: The aim of this study is to determine factors that predict CHB and to develop a clinical tool for risk stratification of patients. METHODS: Patients were enrolled into an ongoing ASA study. A total of 636 patient procedures were included, 527 of whom were used in the development of the prediction tool, and 109 of whom were used for independent validation. Multivariate analysis was performed with odds ratios used to develop the clinical prediction tool. This was then internally and externally validated. RESULTS: Of the 527 in the prediction cohort, 46 developed CHB. The predictors of CHB were age ≥50 years, pre-ASA left bundle branch block (LBBB), transient procedural high-grade block, post-ASA PR prolongation ≥68 ms, and new bifascicular block. An 11-point clinical prediction tool was developed to classify these factors. Internal validation using a receiver operating characteristic curve revealed an area under the curve of 0.88 for the clinical prediction tool. External validation using 109 contemporary patients revealed a 98% negative predictive value, 24% positive predictive value, 75% sensitivity, and 81% specificity in high-risk patients. CONCLUSION: Among patients undergoing ASA, the risk of CHB can be predicted with easily obtained clinical and electrocardiographic factors. This clinical prediction tool allows identification of high-risk patients who may benefit from additional monitoring and therapy.

Reversible complete heart block in a patient with coronavirus disease 2019.

Patients infected with novel coronavirus (SARS-CoV-2) can present with a variety of arrhythmias. We report an unusual case of reversible complete heart block (CHB) in the setting of acute coronavirus disease 2019 (COVID-19). A 23-year-old male with a history of Hodgkin's Lymphoma presented with dizziness and syncope. He was found to be in CHB associated with hypotension requiring a transvenous pacemaker. Methylprednisolone and remdesivir were started with rapid resolution of the CHB. Further study is needed to determine the mechanism of CHB in COVID-19. This case underscores the importance of including COVID-19 in one's differential diagnosis for acute CHB.

Pulmonary hypertensive crisis: A potential reason for right ventricle and pacemaker lead failure.

Cardiac pacemakers have improved patient survival and quality of life, although malfunctions can be seen. We present the case of a girl with Seckel syndrome and congenital complete heart block. She had a single chamber permanent pacemaker in the right ventricle. When she referred us with a pulmonary hypertensive crisis (PHC), it was seen that the device was not pacing even in maximum threshold and pulse width values. After new epicardial lead implantation into the left ventricular apex, capture could be established again. For the cases presenting with capture failure, after eliminating lead-related problems and biochemical abnormalities, PHC should be kept in mind as a reason.

Symptomatic atrial bigeminy masquerading as congenital complete heart block.

Newborn male with symptomatic bradycardia initially diagnosed with complete atrioventricular block. Isoproterenol drip was initiated, and the patient was scheduled for pacemaker implantation. During the hospital course, repeat electrocardiogram and Holter monitor revealed evidence of near continuous blocked atrial bigeminy with occasional aberrantly conducted premature atrial contractions. Flecainide was started, resulting in normal sinus rhythm, and the pacemaker implantation was cancelled.