2:1 Intrahisian block with Wenckebach phenomenon during his bundle pacing.

BACKGROUND: Intrahisian blocks with split His bundle (HB) potentials are occasionally observed in practice with intrahisian Wenckebach phenomenon being rare. CASE PRESENTATION: We report a case of an 85c and third-degree atrioventricular block. Some electrophysiological phenomena were recorded which serve as evidence of second-degree block intrahisian within the HB. During HB pacing (HBP) lead deployment, widening and splitting of HB potential and intrahisian Wenckebach phenomenon were recorded in intracardiac electrogram. Then, we began unipolar HBP at 2 V/0.5 ms. The paced QRS exhibited morphology identical to that during intrinsic rhythm, indicating selective capture of the HB. Notably, pacing the H1 potential at 750 ms results in 2:1 intrahisian block with intrahisian Wenckebach phenomenon. CONCLUSION: The case highlights the interesting finding of second-degree block intrahisian block in the HBP.

Prediction of atrioventricular conduction disturbance after ablation of persistent atrial fibrillation.

The prevalence of atrioventricular conduction disturbance (AVCD) in patients with persistent atrial fibrillation (AF) has not yet been fully investigated. We sought to identify the predictors of AVCD in patients with AF by analyzing the relationship between pre-ablation heart rate during AF and the PR interval in sinus rhythm after ablation. We analyzed pre-ablation 24-h Holter electrocardiogram (ECG) and 12 lead ECG 12 months after ablation of 121 consecutive patients with persistent AF who underwent their first ablation procedure and maintained sinus rhythm at 12 months. AVCD was defined as a first-degree atrioventricular block (AVB), second-degree AVB, high-degree AVB, or third-degree AVB observed on ECG at 12 months after ablation. Seventeen out of 121 patients (14.0%) had AVCD at 12 months. In the group with AVCD, total heartbeat (THB) and maximum heart rate (Max HR) were significantly lower, and the prevalence of concomitant Cavo-tricuspid isthmus-dependent atrial flutter before ablation and the appearance of macro reentrant atrial tachycardia (AT) during the procedure were significantly higher than those in the group without AVCD. Multiple regression analysis revealed that maximum HR and macro reentrant AT were significant predictors of AVCD. Receiver operating characteristic curve analysis revealed that Max HR of <165.0 bpm predicts AVCD with a sensitivity of 76.47% and a specificity of 74.00%. In patients with persistent AF, low Max HR and the presence of macro reentrant AT during the ablation procedure were predictors of AVCD.

Atrioventricular and intraventricular blocks in the setting of acute coronary syndromes: a narrative review.

Acute coronary syndromes (ACS) might be complicated by atrioventricular (AV) and intraventricular (IV) blocks in a significant number of cases, and often represent a diagnostic and a therapeutic challenge. These conduction disturbances are predictors of adverse prognosis, with complete AV blocks presenting the most severe outcomes, showing an increased in-hospital mortality. With the advent of emergency percutaneous coronary intervention (PCI) and the end of the thrombolysis era, the incidence of both AV and IV blocks has surely decreased, but their prognosis in this setting still remains a matter of debate. The aim of this review is to evaluate the current knowledge on AV and IV blocks in the AMI setting with or without ST segment elevation.

Dual atrioventricular nodal pathways physiology and high-grade heart block.

We report of case of an 87 year old lady with preexisting RBBB who developed LBBB after transcatheter aortic valve replacement (TAVR) for the treatment of severe aortic stenosis. She underwent pacemaker implantation, and subsequently developed high-grade atrioventricular (AV) block. Dual chamber pacing in the setting of complete heart block with a long programmed AV delay showed retrograde P waves. Ventricular pacing showed intact retrograde conduction. Shortening the programmed AV delay resulted in loss of retrograde P waves during dual chamber pacing. These findings are discussed.

Immune-Mediated Fetal Complete Atrioventricular Block: Can Dexamethasone Therapy Revert the Process?

BACKGROUND: Fetal complete atrioventricular block (CAVB) is usually autoimmune mediated. The risk of developing CAVB is 2% to 3% in anti-Ro/SS-A seropositive pregnancies and it increases 10 times after previous CAVB in siblings. Despite being a rare complication, CAVB carries a 20% mortality rate and substantial morbidity, as about 65% of newborns will eventually need life-long pacing. Once found, fetal CAVB is almost always irreversible, despite aggressive immunotherapy. This poor outcome prompted some research groups to address this situation. All groups followed anti-Ro/SS-A seropositive pregnancies on a weekly basis during the second trimester of pregnancy and tried to detect first degree atrioventricular block (AVB) using accurate echocardiographic tools, assuming they may characterize the initiation of the immune damage to the A-V conduction system, at which point the process might still be reversible. Some of the groups treated fetuses with first degree AVB with maternal oral fluorinated steroids. We summarized the results of all groups, including our group. We describe a case of a fetus that developed CAVB 6 days after normal sinus rhythm (NSR), who under aggressive dexamethasone therapy gradually reverted to NSR. This fetus had a previous sibling with CAVB. We assumed the immune damage to the conduction system in this small group of fetuses with a previous CAVB sibling may have occurred more quickly than usual. We therefore recommend a twice-weekly follow-up with these fetuses.

Syncope caused by complete heart block and ventricular arrhythmia as early manifestation of systemic lupus erythematosus in a pregnant patient: a case report.

Systemic lupus erythematosus (SLE) can affect all heart structures including the conduction system, with either reversible or permanent derangement. However, only a few cases of adult SLE and complete atrioventricular (AV) block have been reported. We describe a young pregnant woman who initially presented with complete AV block on electrocardiography before the diagnosis of SLE. Syncope subsequently developed during the postpartum period due to frequent nonsustained polymorphic ventricular tachycardia, suggesting lupus myocarditis. The ventricular arrhythmia was successfully treated by intravenous corticosteroids, lidocaine and implantation of a permanent pacemaker. This may represent the first report of complete AV block with polymorphic ventricular tachycardia, which was identified before the other clinical features of SLE fully manifested. SLE should be considered if a patient presents with complete AV block without other clinical features. It may warn for early diagnosis and appropriate treatment of SLE including lupus-related heart disease.

A 1-year-old boy with long pauses caused by paroxysmal atrioventricular block and sinus arrest: Vagal reflex and effect of pacing.

Paroxysmal atrioventricular block (PAVB) is rare in children. A 1-year-old boy presented with PAVB and sinus arrest that resulted in refractory life-threatening symptomatic long pauses. Continuous heart rate variability analysis with high time resolution (wavelet analysis) revealed an abrupt increase in parasympathetic activity just before a long pause, which indicated a vagal reflex. Although a pacemaker is not always effective because of a concomitant vasodepressive response in such cases, the complete stabilization after pacemaker implantation in this case supports the necessity and usefulness of pacemaker implantation in patients with reflex-induced highly symptomatic bradycardia.

Simplified Cardioneuroablation in the Treatment of Reflex Syncope, Functional AV Block, and Sinus Node Dysfunction.

BACKGROUND: Cardio neuroablation (CNA) is a lesser-known technique for management of patients with excessive vagal activation on the basis of radiofrequency catheter ablation (RFCA) of the areas related to the three main autonomic ganglia around the heart. We investigated the effectiveness of selective and/or stepwise RFCA of these areas via right atrium (RA) and/or left atrium (LA) in the patients with recurrent syncope due to excessive vagal activity. METHODS: Twenty-two patients presenting symptomatic functional bradyarrhythmias, neurally mediated reflex syncope (NMS), symptomatic atrioventricular (AV) block, and symptomatic sinus node dysfunction (SND; number = 8, 7, 7, respectively) were enrolled. The three main paracardiac ganglia were targeted via RA and LA in the patients with NMS and SND. The procedure was performed via RA in the patients with AV block, followed by RFCA of all ganglia via LA, if AV conduction disorder persists. The sites showing fragmented potentials were identified by electrical mapping and verified by high-frequency stimulation and ablated until atrial electrical potential was completely eliminated (<0.1 mV). RESULTS: The patients with NMS and SND were free from new syncopal episode at a mean 12.3 ± 3.4 months and 9.5 ± 3.1 months follow-up, respectively. Ablation from RA was successful in six of seven patients with AV block. Despite the increased heart rate, the resolution of AV block after the RFCA could not be achieved in one patient who had partial resolution with atropine infusion on admission. CONCLUSION: CNA may be an alternative and safe strategy to reduce NMS episodes, and to treat functional AV block and symptomatic SND, especially in young patients.

A case of reversible third-degree AV block due to Lyme carditis.

The most common manifestation of Lyme carditis is a varying degree of atrioventricular (AV) conduction block. This case describes a 45-year-old male with third-degree AV block due to Lyme carditis. Treatment with intravenous antibiotics resulted in complete normalization of AV conduction, thereby averting permanent pacemaker implantation.

[A series of cases--too old for a pacemaker?]. / Eine Case Serie--Zu alt für einen Schrittmacher?

We report three patients with an age above 90 years presented with symptomatic bradycardia and higher grade AV block in our clinic. The oldest patient was 100 years. All three patients could be supplied safely and without complications with a dual chamber pacemaker. Our case series shows that a dual chamber pacemaker implantation is safe and feasible in patients in very advanced age. A surgical management with local anesthetic (lidocaine), fentanyl and midazolam in individual cases is possible. This and a short hospital stay reduce the risk of delirium. It is a group of patients, which will increase in the future and requires more intensive care than the standard pacemaker patient.

Recovery of Ventriculo-Atrial Conduction after Adrenaline in Patients Implanted with Pacemakers.

BACKGROUND: Ventriculo-atrial (VA) conduction can have negative consequences for patients with implanted pacemakers and defibrillators. There is concern whether impaired VA conduction could recover during stressful situations. Although the influence of isoproterenol and atropine are well established, the effect of adrenaline has not been studied systematically. The objective of this study was to determine if adrenaline can facilitate recovery of VA conduction in patients implanted with pacemakers. METHODS: A prospective study was conducted on 61 consecutive patients during a 4-month period (April-July 2014). The presence of VA conduction was assessed during the pacemaker implantation procedure. In case of an impaired VA conduction, adrenaline infusio was used as a stress surrogate to test conduction recovery. RESULTS: The indications for pacemaker implantation were: sinus node dysfunction in 18 patients, atrioventricular (AV) block in 40 patients, binodal dysfunction (sinus node+ AV node) in two patients and other (carotid sinus syndrome) in one patient. In the basal state, 15/61 (24.6%) presented spontaneous VA conduction and 46/61 (75.4%) had no VA conduction. After administration of adrenaline, there was VA conduction recovery in 5/46 (10.9%) patients. CONCLUSIONS: Adrenaline infusion produced recovery of VA conduction in 10.9% of patients with absent VA conduction in a basal state. Recovery of VA conduction during physiological or pathological stresses could be responsible for the pacemaker syndrome, PMT episodes, or certain implantable cardiac defibrillator detection issues.

Cardiac memory during rather than after termination of left bundle branch block.

An 83-year-old woman with chronic left bundle branch block and remote history of pacemaker implantation for intermittent AV block was hospitalized for fatigue and leg swelling. She had no cardiac complaints. Routine 12-lead electrocardiogram showed sinus rhythm with left bundle branch block. There were diffuse negative T waves in the inferior and anterolateral leads that were concordant with the QRS complexes. Echocardiogram was normal and nuclear perfusion heart scan showed no abnormality. It was noted that the negative T waves during left bundle branch block were in the exact same leads as were the deep negative QRS complexes during ventricular pacing. The electrocardiographic changes were consistent with cardiac memory. This case is unique because cardiac memory in patients with intermittent left bundle branch block typically occurs when the QRS complexes normalize and not during left bundle branch block itself. Our findings indicate that memory Ts can develop not only after normalization of wide complex rhythms but also with alternating wide complex rhythms as in the presented case where a ventricular paced rhythm was replaced by left bundle branch block.

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.

Phase 4 paroxysmal AV block in a patient with scleroderma.

A 72-year-old man with limited cutaneous systemic scleroderma was hospitalized for two episodes of witnessed syncope. The baseline 12-lead electrocardiogram was normal but on telemetry there were numerous episodes of paroxysmal AV block with asystolic periods of up to 7.5 s duration. Analysis of the rhythm strips revealed phase 4 intra-His bundle block characterized by critical P-P intervals that triggered the AV block, and a narrow range of junctional escape to subsequent P wave intervals that were required to release the AV block. A dual chamber pacemaker was implanted.

Regular tachycardia terminated by ventricular anti-tachycardia pacing in an ICD recipient. What is the mechanism?

This is the case of a misdiagnosed atrioventricular nodal reentry tachycardia (AVNRT) with occasionally 2:1 atrioventricular block terminated by delivery of an inappropriate ventricular antitachycardia pacing scheme, in an ICD recipient. The detailed analysis of stored electrograms facilitated the revelation of the arrhythmic mechanism.