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.

POPDC1 Variants Cause Atrioventricular Node Dysfunction and Arrhythmogenic Changes in Cardiac Electrophysiology and Intracellular Calcium Handling in Zebrafish.

Popeye domain-containing (POPDC) proteins selectively bind cAMP and mediate cellular responses to sympathetic nervous system (SNS) stimulation. The first discovered human genetic variant (POPDC1S201F) is associated with atrioventricular (AV) block, which is exacerbated by increased SNS activity. Zebrafish carrying the homologous mutation (popdc1S191F) display a similar phenotype to humans. To investigate the impact of POPDC1 dysfunction on cardiac electrophysiology and intracellular calcium handling, homozygous popdc1S191F and popdc1 knock-out (popdc1KO) zebrafish larvae and adult isolated popdc1S191F hearts were studied by functional fluorescent analysis. It was found that in popdc1S191F and popdc1KO larvae, heart rate (HR), AV delay, action potential (AP) and calcium transient (CaT) upstroke speed, and AP duration were less than in wild-type larvae, whereas CaT duration was greater. SNS stress by ß-adrenergic receptor stimulation with isoproterenol increased HR, lengthened AV delay, slowed AP and CaT upstroke speed, and shortened AP and CaT duration, yet did not result in arrhythmias. In adult popdc1S191F zebrafish hearts, there was a higher incidence of AV block, slower AP upstroke speed, and longer AP duration compared to wild-type hearts, with no differences in CaT. SNS stress increased AV delay and led to further AV block in popdc1S191F hearts while decreasing AP and CaT duration. Overall, we have revealed that arrhythmogenic effects of POPDC1 dysfunction on cardiac electrophysiology and intracellular calcium handling in zebrafish are varied, but already present in early development, and that AV node dysfunction may underlie SNS-induced arrhythmogenesis associated with popdc1 mutation in adults.

Diagnosis and treatment of recurrent syncope in a middle-aged women.

A 50-year-old female patient, presented with repeated syncope for more than 2 years. Prior assessments were conducted at different hospitals, but no definite abnormalities were found. The patient's fear and anxiety about possible future attacks were escalating. Through a Head-up tilt test, the cause was finally identified as vasovagal syncope. Following a 5-min administration of nitroglycerin, the patient reported palpitations, nausea, and deep, rapid breathing. The electrocardiogram initially showed a first-degree atrioventricular block, progressing swiftly to a second-degree type I atrioventricular block-high atrioventricular block. Immediate intervention was undertaken, but blood pressure was not instantly ascertainable, coinciding with an abrupt loss of consciousness. Subsequent electrocardiographic findings included paroxysmal third-degree atrioventricular block, sinus arrest, and complete cardiac arrest, prompting the initiation of external cardiac compressions. The longest recorded ventricular arrest approximated 15 s, with sinus rhythm resuming post 10 s of cardiac compressions and the patient regaining consciousness. The patient underwent vagal ablation and no longer experienced syncope.

Pembrolizumab-induced myocarditis with complete atrioventricular block and concomitant myositis in a metastatic bladder cancer patient: a case report and review of the literature.

BACKGROUND: The cardiovascular system is among the least systems affected by immune-related adverse events. We report a rare life-threatening case of pembrolizumab-induced myocarditis with complete atrioventricular block and concomitant myositis in a metastatic bladder cancer patient. CASE PRESENTATION: An 82-year-old Caucasian female with invasive urothelial carcinoma, started on first-line pembrolizumab, was admitted four days after receiving her second dose for severe asthenia, diffuse muscle aches, neck pain, and lethargy. In the emergency department, she had several episodes of bradycardia reaching 40 beats per minute associated with general discomfort and fatigue. Electrocardiography showed a third-degree atrioventricular heart block, while the patient remained normotensive. Cardiac damage parameters were altered with elevated levels of creatine phosphokinase of 8930 U/L, suggestive of immune checkpoint inhibitor-induced myositis, and troponin T of 1.060 ng/mL. Transthoracic echocardiography showed a preserved ejection fraction. Pembrolizumab-induced myocarditis was suspected. Therefore, treatment was initiated with high-dose glucocorticoids for 5 days, followed by a long oral steroid taper. A pacemaker was also implanted. Treatment resulted in the resolution of heart block and a decrease in creatine phosphokinase to the normal range. CONCLUSION: Life-threatening cardiac adverse events in the form of myocarditis may occur with pembrolizumab use, warranting vigilant cardiac monitoring. Troponin monitoring in high-risk patients, along with baseline echocardiography may help identify this complication promptly to prevent life-threatening consequences.

BRASH syndrome with a complete heart block- a case report.

INTRODUCTION: BRASH syndrome (Bradycardia, Renal failure, Atrioventricular (AV) nodal blocking agent, Shock and Hyperkalemia) is a recently emerging diagnosis that describes the profound bradycardia seen in patients on AV nodal blockers who present with acute kidney injury (AKI) and hyperkalemia. CASE PRESENTATION: We present a case of a 68 years old female patient with past history of hypertension taking atenolol and Enalapril presented to emergency department with the complaint of loss of consciousness of 02 hours duration. She had 03 days history of fatigue, poor oral intake, decreased urine output, appetite loss, vertigo and global headache. Her vital signs were blood pressure of 60/40 mmHg, absent radial pulse and temperature of 36.4 °C. Her systemic examination was remarkable for dry buccal mucosa; apical heart rate was 22 beats per minute. Glasgow Coma Scale was 13/15. Her laboratory tests showed creatinine of 1.83 mg/dL, blood urea nitrogen of 89 mg/dL and potassium elevated to the level of 6.39 mEq/dL. ECG revealed complete heart block with a normal QT interval and T waves and no U waves with ventricular rate of 22 beats per minute. Her previous medications were discontinued and the patient was resuscitated with intravenous (IV) fluids. She was given 03 doses of 1 mg atropine every 5 minutes but there was no increment in heart rate. She was given 50% dextrose with 10 international units of regular insulin, 1 g of calcium gluconate and Intravenous perfusion of norepinephrine and dopamine. Subsequently, after 14 hours of ICU admission the patient had a cardiac arrest with asystole and resuscitation was attempted but she couldn't survive. CONCLUSION: BRASH syndrome is largely an under-recognized life threatening clinical diagnosis. Physicians should have high index of suspicion for BRASH when they encounter patients with bradycardia, hyperkalemia, and renal failure, as timely diagnosis is crucial in the management.

Atrioventricular block in patients with hyperthyroidism: a narrative review.

Atrioventricular block (AVB) is a rare cardiac manifestation of hyperthyroidism (HTH). The scientific literature contains multiple reports of AVB in patients with HTH, ranging from subclinical to overt HTH and even thyroid storm. However, much remains unknown about the true prevalence, clinical course, optimal management, and outcomes of AVB in patients with HTH. Such patients are possibly overtreated with pacemakers because of a lack of understanding that AVB might be secondary to the hyperthyroid state and thus reversible. This narrative review discusses the pathophysiology of AVB in patients with HTH in the context of the available evidence.

Diagnostic Dilemma of Syncope: Esophageal Hiatal Hernia and High-risk Bundle-branch Block.

We herein report a complicated case of recurrent syncope accompanying bundle branch block and hiatal hernia of the esophagus. An 83-year-old woman presented with syncope. Echocardiography visualized the left atrium compressed by an esophageal hiatal hernia, which had potential to decrease the cardiac output. Although she underwent esophageal repair surgery, two months after the surgery, she presented to the emergency department again with complaints of syncope. At the return visit, her face was pale and her pulse rate was 30 beats per minute. Electrocardiography showed complete atrioventricular block. On reviewing the patient's previous electrocardiography findings, we found a record of trifascicular block. This case illustrates the importance of predicting atrioventricular blocks in patients with high-risk bundle-branch blocks. Keeping in mind high-risk bundle-branch blocks will help clinicians avoid anchoring bias due to a striking image masquerading as the true diagnosis.

Cardiovascular Adverse Events Associated With Second-generation Bruton Tyrosine Kinase Inhibitor Therapy: A Systematic Review and Meta-analysis.

PURPOSE: Cardiovascular adverse events (CVAEs) are common adverse effects of first-generation Bruton tyrosine kinase inhibitors (BTKis) and limit their use considerably. This led to the development of second-generation BTKis-acalabrutinib and zanubrutinib-which are more selective, potent, and presumed to have better safety profiles than the previous group of medications. However, there have been sporadic reports of CVAEs associated with second-generation BTKis in clinical practice. To address this issue, a comprehensive meta-analysis to pool the documented CVAEs was performed, including major hemorrhage, any bleeding, atrioventricular block, atrial fibrillation/flutter, pericardial effusion, pericarditis, heart failure, cardiac arrest, myocardial infarction, hypertension, hypotension, and stroke. This meta-analysis incorporated 8 studies. Among these, 6 were Phase III trials and 2 were Phase II trials. These studies collectively enrolled a total of 2938 patients. METHODS: Multiple databases, including PubMed, MEDLINE, Cochrane Library, Scopus, and EMBASE, were systematically searched for relevant clinical trials from inception through January 14, 2023. The effect measure used was odds ratio (OR) and 95% CI. FINDINGS: Of a total of 1774 studies identified during the initial database search, 8 were included in the meta-analysis. The incidence of overall and cardiovascular mortality was comparable between the 2 groups. There were no significant differences observed for cardiovascular mortality (OR = 0.36; 95% CI, 0.08-1.65; n = 2588; I2 = 45%; P = 0.19). Similar results were found for all-cause mortality (OR = 0.85; 95% CI, 0.67-1.07), any bleeding (OR = 1.90; 95% CI, 0.88-4.09), major bleeding (OR = 1.07; 95% CI, 0.65-1.76), atrioventricular block (OR = 0.74; 95% CI, 0.15-3.68), atrial fibrillation/flutter (OR = 0.74; 95% CI, 0.37-1.50), and other CVAEs associated with second-generation BTKis. IMPLICATIONS: Based on the available evidence, there is no indication of worse cardiovascular outcomes or superiority of second-generation BTKis compared with standard treatments in terms of safety profile. However, additional large-scale controlled trials are needed to provide robust support for the superior tolerability of new-generation BTKis.

An Unusual Case of Lyme Carditis With Persistent Third-Degree Heart Block.

Lyme's carditis and neuroborreliosis are common manifestation of disseminated Lyme disease. However, third-degree atrioventricular blocks with Lyme's carditis requiring permanent pacemaker with neuroborreliosis and Lyme's disease-associated immunodeficiency are uncommon. Here we present a case of 64-year-old female presenting with neurological symptoms and electrocardiogram changes suggestive of complete heart block with no improvement in the degree of heart block with intravenous antibiotics, requiring permanent pacemaker implantation and course complicated by fungemia.

An unmet need: arrhythmia detection by implantable loop recorder in the systemic right ventricle.

AIMS: Patients with systemic right ventricles are at high risk of sudden cardiac death. Arrhythmia is a significant risk factor. Routine Holter monitoring is opportunistic with poor adherence. The aim of this study was to determine if continuous rhythm monitoring with an implantable loop recorder (ILR) could allow early detection of clinically important arrhythmias. METHODS AND RESULTS: Implantable loop recorder implantation was offered to patients with atrial switch repair for transposition of the great arteries. Recordings were made with symptoms or, automatically for pauses, significant bradycardia or tachycardia and reviewed by the multi-disciplinary team. Twenty-four out of 36 eligible patients underwent ILR implantation with no complication. Forty-two per cent had preserved ventricular function, 75% were NYHA functional class I, 88% had low sudden cardiac death risk, 33% had previous intra-atrial re-entrant tachycardia (IART), and none had known conduction disease. Eighteen out of 24 (75%) patients made 52 recordings (52% automated) over 39.5 months (1.6-72.5). Thirty-two out of 52 (62%) recordings in 15/24 (63%) of the cohort were clinically significant and included sinus node disease (two patients), atrioventricular block (two patients), IART (seven patients), and IART with sinus node disease or atrioventricular block (four patients). Implantable loop recorder recordings prompted medication change in 11 patients [beta-blockers (n = 9), anti-coagulation (n = 5), and stopping anti-coagulation (n = 1)] and device therapy recommendation in seven patients [five pacemakers (three: atrioventricular block) and two defibrillators]. Two patients declined intervention; one suffered an arrhythmic death. Intra-atrial re-entrant tachycardia and clinically relevant conduction disease were detected in patients irrespective of sudden cardiac death risk. CONCLUSION: Continuous monitoring with an ILR in patients with systemic right ventricle following atrial switch detects clinically relevant arrhythmias that impact decision-making. In this cohort, clinically relevant arrhythmias did not correlate with sudden cardiac death risk.

Strong independent association between third-degree AV-block and diabetes mellitus using a large database.

BACKGROUND: Recent data suggests an association between DM and third-degree AV- Block. The goal of this study was to evaluate the independent association between diabetes and third-degree AV-Block using a very large database. METHOD: We used ICD-9 Codes for DM and third-degree AV-block from the Nationwide Inpatient Sample (NIS) database. We randomly selected the 1992 and 2002 databases which are 10 years apart as two independent samples. We used uni- and multi-variate analysis to evaluate this association. RESULTS: 1992 database contained a total of 6,195,744 patients. Diabetes occurred in (0.5 %) of patients with third-degree AV-block vs. (0.2 %) of the control (OR: 2.15, CI 2.06-2.25, p < 0.0001). 2002 database contained a total of 7,853,982 patients. Diabetes occurred in (0.4 %) of patients with third-degree AV-block vs. (0.2 %) of the control (OR: 1.86, CI: 1.80-1.93, p < 0.0001). Using Multivariate analysis adjusting for age, congestive heart failure, and coronary artery disease, DM remained independently associated with third-degree AV block in both databases. (for 1999: OR: 2.54, CI 2.51-2.57, p < 0.0001 and for 2002 OR: 1.56, CI 1.55-1.57, p < 0.0001). CONCLUSION: DM is independently associated with third-degree AV-block with persistent association over a period of 10 years. The cause of this association warrants further investigation.

Failure of diltiazem to prevent 1:1 conduction of atrial flutter: a case report.

BACKGROUND: Atrial flutter with 1:1 conduction to the ventricles is a dangerous cardiac arrhythmia. Contemporary guidelines recommend atrioventricular nodal blocking agents should be co-administered with class 1C anti-arrhythmics, as prophylaxis against 1:1 flutter. No guidance is provided on the type or strength of atrioventricular nodal blockade required, and in practice, these agents are frequently prescribed at low dose, or even omitted, due to their side effect profile. CASE PRESENTATION: A 62 year old Caucasian man with a history of paroxysmal atrial fibrillation treated with flecainide, presented with atrial flutter with 1:1 conduction to the ventricles and was cardioverted. Diltiazem was added to prevent this complication and he again presented with atrial flutter with 1:1 conduction to the ventricles, despite prophylaxis with coadministration of diltiazem. CONCLUSIONS: This case report demonstrates failure of diltiazem to prevent 1:1 flutter in a patient chronically treated with flecainide for paroxysmal atrial fibrillation.

Delayed Right Ventricular Pacemaker Lead Perforation 9 Years After Implantation.

BACKGROUND Cardiac perforation is a rare complication of cardiac implantable electronic devices, with a reported incidence ranging from 0.1% to 5.2%. Delayed perforation, defined as perforation occurring more than 1 month after implantation, is more uncommon. In this report, we present a case of cardiac perforation involving the right ventricle wall that occurred 9 years after pacemaker implantation. CASE REPORT A 79-year-old woman presented with symptoms of dyspnea and was subsequently admitted to a hospital. She had undergone pacemaker implantation for a complete atrioventricular block 9 years prior to the presentation. The patient had right ventricular failure to capture and a resultant complete atrioventricular block. Computed tomography imaging revealed that the right ventricular lead had clearly protruded outside the heart; however, no pericardial effusion was observed. When the patient underwent open surgical repair, the ventricular tined lead was noted to be traversing the right ventricular apex. Device interrogation revealed a sudden increase followed by a gradual decrease in the right ventricular pacing threshold over the course of 2 months, indicating that the lead had slowly traversed the right ventricular muscle before ultimately rupturing through it. CONCLUSIONS This study described the case of a delayed right ventricular pacemaker lead perforation that occurred 9 years after implantation, which was managed via open surgical repair.

A mix of aminophylline and heparin plus nitroglycerin can reduce bradycardia during rotational atherectomy on the right coronary artery and dominant circumflex artery.

BACKGROUND: Rotational atherectomy (RA) may cause bradyarrhythmias and transitory atrioventricular block when performed in the right coronary artery (RCA) or a dominant circumflex (CX) coronary artery. However, there are no studies of a solution that can prevent coronary flow deterioration and bradycardia complications that may occur during RA. We aimed to create an alternative rota-flush solution to minimize the risk of bradycardia and complete atrioventricular block (AVB) that can occur during RA. MATERIALS AND METHODS: The study comprised 60 patients who were randomly divided into two groups: 30 received rotaphylline (= 240 mg aminophylline, 10,000 U unfractionated heparin, and 2000 mcg nitroglycerin to 1000 mL saline), and 30 received the traditional rota-flush (= 10,000 U unfractionated heparin, 2000 mcg nitroglycerin, and 1000 mL saline). The incidence of bradycardia or high-grade AVB (HAVB) during RA, coronary slow-flow phenomenon or no-reflow phenomenon, and coronary spasm were the primary endpoints of the study. Procedure success and RA-related procedural complications were secondary endpoints. RESULTS: The use of rotaphylline was an independent predictor of bradycardia and HAVB after accounting for all other factors (OR: 0.47, 95% CI: 0.24-0.79, p < 0.001). Lesion length (OR: 2.17, 95% CI: 1.24-3.04, p < 0.001), burr-to-artery ratio (OR: 0.59, 95% CI: 0.39-1.68, p < 0.001), and total run duration (OR: 0.79, 95% CI: 0.35-1.43, p < 0.001) were additional independent predictors. CONCLUSION: Bradycardia and the development of HAVB may be avoided by rotaphylline intracoronary infusion during RA applied to the RCA and dominant CX lesions. Multicenter studies including sizable patient populations should be conducted to validate the present findings.

Congenitally Corrected Transposition of the Great Arteries: Fetal Diagnosis, Associations, and Postnatal Outcome: A Fetal Heart Society Research Collaborative Study.

Background Fetal diagnosis of congenitally corrected transposition of the great arteries (ccTGA) has been increasingly reported; however, predictors of clinical outcomes remain underexplored. We undertook a multicenter, retrospective study to investigate natural history, associated anomalies, and outcomes of fetal ccTGA. Methods and Results Fetuses with ccTGA diagnosed from January 2004 to July 2020 within 20 North American programs were included. Fetuses with severe ventricular hypoplasia thought to definitively preclude biventricular repair were excluded. We included 205 fetuses diagnosed with ccTGA at a median gestational age of 23 (interquartile range, 21-27) weeks. Genetic abnormalities were found in 5.9% tested, with extracardiac anomalies in 6.3%. Associated cardiac defects were diagnosed in 161 (78.5%), with atrioventricular block in 23 (11.3%). On serial fetal echocardiogram, 39% demonstrated a functional or anatomic change, most commonly increased tricuspid regurgitation (6.7%) or pulmonary outflow obstruction (11.1%). Of 194 fetuses with follow-up, 26 were terminated, 3 experienced fetal death (2 with atrioventricular block), and 165 were live-born. Of 158 with postnatal data (median follow-up 3.7 years), 10 (6.6%) had death/transplant before 1 year. On univariable analysis, fetal factors associated with fetal death or death/transplant by 1 year included ≥ mild tricuspid regurgitation, pulmonary atresia, aortic obstruction, fetal arrhythmia, and worsening hemodynamics on serial fetal echocardiogram (defined as worse right ventricular function, tricuspid regurgitation, or effusion). Conclusions Associated cardiac lesions and arrhythmias are common in fetal ccTGA, and functional changes commonly occur through gestation. Worse outcomes are associated with fetal tricuspid regurgitation (≥mild), any arrhythmia, pulmonary atresia, aortic obstruction, and worsening hemodynamics on serial echocardiograms. These findings can inform prenatal counseling and perinatal management planning.

Outcomes Associated With Early vs. Delayed Invasive Strategy in NSTEMI Complicated by High Degree AV Block: A Nationwide Analysis.

Background: High degree atrioventricular block (HDAVB) is an uncommon complication of non-ST-segment elevation myocardial infarction (NSTEMI) that frequently necessitates pacemaker implantation. This contemporary analysis compares need for pacemaker implantation based on the timing of intervention in acute NSTEMI complicated by HDAVB.Methods: We used 2016-2017 National Inpatient Sample database to identify admissions with NSTEMI and HDAVB. Time to coronary intervention from initial admission was used to segregate the admissions into two groups: early invasive strategy (EIS) (<24 hours) and delayed invasive strategy (DIS) (>24 hours). Multivariable linear and logistic regression analysis was performed to compare in-hospital outcomes among the two groups.Results: Out of 949,984 NSTEMI related admissions, coexistent HDAVB was present in 0.7% (n=6725) patients. Amongst those, 55.61% (n=3740) hospitalizations included invasive intervention (EIS=1320, DIS=2420). Patients treated with EIS were younger (69.95 years vs. 72.38 years, P<0.05) and had concomitant cardiogenic shock. Contrarily, prevalence of chronic kidney disease, heart failure, and pulmonary hypertension was higher in DIS group. EIS was associated with lower length of stay and total hospitalization cost. In-hospital mortality and pacemaker implantation rates were not significantly different between patients in the EIS and DIS groups.Conclusion: HDAVB is a rare complication of NSTEMI and often associated with right coronary artery disease. The timing of revascularization does not appear to influence the rate of pacemaker placement in NSTEMI complicated by HDAVB. Further studies are needed to assess if early invasive strategy can benefit all patients with NSTEMI and HDAVB.

Unusual manifestation of atypical type I second degree atrioventricular block.

A 25 year-old woman exhibited atypical type I second degree atrioventricular block characterized by constant PR intervals except the PR interval of the beat after the block. This was attributed to vagally induced AV block with failure of the vagal effect to depress the sinus node.

Third-degree atrioventricular block associated with severe acute hyponatraemia.

Severe acute hyponatraemia, defined as a sodium concentration of less than 120 mEq/L, typically manifests with neurological manifestations, resulting in obtundation, coma, seizures, respiratory arrest and death. It very rarely is arrhythmogenic, with a literature review revealing seven cases of hyponatraemia-associated atrioventricular (AV) block of various degrees, of which only three were described as having third-degree AV block. The higher-degree AV blocks typically occurred at sodium levels closer to 115 mEq/L. We present a case of severe acute hypo-osmolar hyponatraemia-induced third-degree AV block in a patient without any other risk factors or aetiologies who initially presented with subdural haematoma and developed refractory bradycardia during his admission. The patient's third-degree AV block completely resolved after correction of his sodium. This case highlights the importance of working up the cause of new-onset third-degree AV block and the consideration of rarer electrolyte derangements such as hyponatraemia as a potential cause.