Transient Complete Atrioventricular Block Associated With Herbal Supplement Use.

INTRODUCTION: Increasing and easy availability of so-called natural/herbal supplements pose the unique challenge of identifying associated side effects, including arrhythmias in otherwise-healthy individuals. CASE PRESENTATION: A 25-year-old female patient presented to the emergency department with fatigue and lightheadedness. The electrocardiogram showed complete AV block with a junctional escape rhythm at 55 beats per minute with QT prolongation (542ms). One week ago, she started to use a herbal medication (Muscle Eze Advanced) for muscle cramps after workouts. Extensive cardiac testing, including complete blood count, complete metabolic panel, TSH, transthoracic echocardiography, urine drug analysis, Lyme antibody were negative. Normal sinus rhythm was restored spontaneously within 1 day of discontinuing the herbal medication. PR and corrected QT intervals returned to baseline over the next two weeks. CONCLUSION: Muscle Eze Advanced consists of seven ingredients, including Melissa officinalis and Valeriana officinalis that have negative chronotropic, negative dromotrophic and QT prolonging effects. Recognizing the association between certain over-the-counter supplements and brady-arrhythmias may circumvent need for permanent pacemakers - an important consideration especially in the young.

Septal versus apical pacing sites in permanent right ventricular pacing: The multicentre prospective SEPTAL-PM study.

BACKGROUND: The optimal right ventricular pacing site for patients requiring pacemaker implantation for permanent atrioventricular block is a matter of debate. Long-term right ventricular apical pacing has been associated with left ventricular ejection fraction impairment and heart failure. Right ventricular septal pacing has been proposed as an alternative. AIM: The aim of this randomized prospective multicentre trial was to compare left ventricular remodelling and outcomes between right ventricular apical and septal pacing after mid-term follow-up. METHODS: Patients requiring pacemaker implantation for high-degree atrioventricular block were enrolled and randomized in a 1:1 fashion to receive a right ventricular apical or septal lead. RESULTS: A total of 141 patients were included, 69 in the septal group and 72 in the apical group. Both groups exhibited similar left ventricular ejection fractions after 18 months of follow-up (septal 57.1±11.9% vs. apical 57.4±13.4%), and left ventricular ejection fraction variation was similar in the two groups at the end of follow-up (septal -1.5±13.2% vs. apical 0.3±13.3%). Additionally, left ventricular volume, quality of life and 6-minute walk distance were similar in the two groups. However, patients in the septal group were more likely to be asymptomatic, with a significantly lower concentration of N-terminal prohormone of brain natriuretic peptide. Lastly, lead position did not impact 18-month survival. CONCLUSION: Pacing from the right ventricular apex does not have any detrimental effect on left ventricular systolic function compared with septal pacing over an 18-month period.

Mobitz Type II Atrioventricular Heart Block After Candlenut Ingestion.

The candlenut is a highly accessible seed marketed as a natural weight-loss supplement. However, there is little known about the exact mechanism of action for weight loss nor for the many adverse symptoms it causes, such as nausea, vomiting, fatigue, cardiac dysrhythmias, and even death. In this case report, the authors present a 44-year-old woman who developed a second-degree, Mobitz type II atrioventricular block after consumption of a candlenut supplement. She presented to the emergency department with syncope and her cardiac rhythm indicated a second-degree heart block soon after ingesting candlenuts recommended by her treating physician. Interestingly, a detectable digoxin concentration obtained on hospital day 2 was measured but of unclear significance given no obvious exposure to a cardioactive glycoside. The patient's rhythm normalized on hospital day 2 and she was discharged uneventfully.

The Utility of Rapid Atrial Pacing Immediately Post-TAVR to Predict the Need for Pacemaker Implantation.

OBJECTIVES: The aim of this study was to determine the utility of rapid atrial pacing immediately after transcatheter aortic valve replacement (TAVR) to predict the need for permanent pacemaker implantation (PPI). BACKGROUND: Risk stratification for patients without high-grade atrioventricular block (AVB) after TAVR is imprecise and based on anatomic considerations, electrocardiographic characteristics, and clinical suspicion. A more reliable assessment is necessary to minimize inpatient rhythm monitoring and/or reduce unnecessary PPI. METHODS: Consecutive patients undergoing TAVR at 2 centers were included. After valve implantation in patients without pacemakers who did not have complete heart block or atrial fibrillation, the temporary pacemaker was withdrawn from the right ventricle and placed in the right atrium. Rapid atrial pacing was performed from 70 to 120 beats/min, and patients were assessed for the development of Wenckebach AVB. Patients were then followed for clinical outcomes, including PPI. RESULTS: A total of 284 patients were included. Of these, 130 (45.8%) developed Wenckebach AVB. There was a higher rate of PPI within 30 days of TAVR among the patients who developed Wenckebach AVB (13.1% vs. 1.3%; p < 0.001), with a negative predictive value for PPI in the group without Wenckebach AVB of 98.7%. A greater percentage of patients receiving self-expanding valves required PPI than those receiving a balloon-expandable valves (15.9% vs. 3.7%; p = 0.001), though these rates were still relatively low among patients who did not develop Wenckebach AVB (2.9% and 0.8%). CONCLUSIONS: Atrial pacing post-TAVR is easily performed and can help identify patients who may benefit from extended rhythm monitoring. Patients who did not develop pacing-induced Wenckebach AVB demonstrated an extremely low likelihood of PPI.

Treatment of atypical pacemaker-mediated tachycardia with ablation of the retrograde atrioventricular nodal pathway.

A 25-year-old runner received a single-lead, VDD pacemaker after ablation of AV nodal reentrant tachycardia complicated by intermittent AV block. The rate-adaptive AV delay algorithm (RAAV), which shortens the sensed AV interval (SAV) at faster atrial rates, was programmed to provide a physiologic SAV with exercise. She developed repetitive, atypical, long-RP pacemaker-mediated tachycardia (PMT) because the RAAV shortened the antegrade SAV and retrograde conduction occurred over the slow AV nodal pathway. PMT was refractory to usual programming solutions. Using high-density electroanatomic mapping, we were able to ablate the retrograde limb of PMT without further damaging AV conduction.

Electrophysiology Testing to Stratify Patients With Left Bundle Branch Block After Transcatheter Aortic Valve Implantation.

Background Left bundle branch block (LBBB) is common after transcatheter aortic valve implantation (TAVI) and is an indicator of subsequent high-grade atrioventricular block (HAVB). No standardized protocol is available to identify LBBB patients at risk for HAVB. The aim of the current study was to evaluate the safety and efficacy of an electrophysiology study tailored strategy in patients with LBBB after TAVI. Methods and Results We prospectively analyzed consecutive patients with LBBB after TAVI. An electrophysiology study was performed to measure the HV-interval the day following TAVI. In patients with normal His-ventricular (HV)-interval ≤55 ms, a loop recorder was implanted (ILR-group), whereas pacemaker implantation was performed in patients with prolonged HV-interval >55 ms (PM-group). The primary end point was occurrence of HAVB during a follow-up of 12 months. Secondary end points were symptoms, hospitalizations, adverse events because of device implantation or electrophysiology study, and death. Of 373 patients screened after TAVI, 56 patients (82±6 years, 41% male) with LBBB were included. HAVB occurred in 4 of 41 patients (10%) in the ILR-group and in 8 of 15 patients (53%) in the PM-group (P<0.001). We did not identify other predictors for HAVB than the HV interval. The negative predictive value for the cut-off of HV 55 ms to detect HAVB was 90%. No HAVB-related syncope occurred in the 2 groups. Conclusions An electrophysiology study tailored strategy to LBBB after TAVI with a cut-off of HV >55 ms is a feasible and safe approach to stratify patients with regard to developing HAVB during a follow-up of 12 months.

An unusual case of AV block.

Nerium oleander is an evergreen small tree, very used in some countries such as India and in Sri Lanka as a self-medication method. We report a case of a 55 year-old man with intermittent, advanced AV block secondary to oleander intoxication.

Fragmented endocardial signals and early afterdepolarizations during torsades de pointes tachycardia.

BACKGROUND: Bradycardia-induced torsade de pointes (TdP) tachycardia in patients with spontaneous high-degree atrioventricular block (AVB) is common. The aim of this study was to analyze endocardial recordings during TdP in spontaneous high-degree AVB in humans to better understand the electrophysiological mechanisms underlying this phenomenon. METHODS: The study group consisted of 5 patients with typical episodes of TdP during spontaneous high-degree AVB. A standard (USCI) temporary bipolar endocardial catheter positioned at the apex of the right ventricle (RV) and bipolar chest leads from two precordial leads V1 and V4 were used to record the tracings during TdP. RESULTS: The presence of a wide spectrum of fragmentations was noted on endocardial electrograms (EGMs), which were invisible on the surface electrocardiogram (ECG) tracing. Endocardial signals indicated that TdP started in the proximity of the RV apex, since the local EGM began prior to the QRS complex on the surface ECG. Early afterdepolarizations (EADs) were observed in 2 out of 5 cases confirming a common opinion about the mechanism of TdP. However, this phenomenon was not observed in 3 other patients suggesting that the arrhythmia was the result of a different mechanism originating in proximity to the RV apex. CONCLUSIONS: This work demonstrated early endocardial signals in the RV apex during TdP associated with high-degree AVB in humans, and exhibits a spectrum of fragmented signals in this area occurring on a single or multiple beats. These fragmentations indicate areas of poor conduction and various degrees of intramyocardial block, and therefore a new mechanism of TdP tachycardia in some patients with spontaneous high-degree AVB.

Point of View: Electrophysiological Endpoints Differ When Comparing the Mode of Action of Highly Successful Anti-arrhythmic Drugs in the CAVB Dog Model With TdP.

In the anaesthetized, chronic atrioventricular block (CAVB) dog, ventricular ectopic beats and Torsade de pointes arrhythmias (TdP) are believed to ensue from an abrupt prolongation of ventricular repolarization and increased temporal dispersion of repolarization, quantified as short-term variability (STV). These TdP stop spontaneously or, when supported by substantial spatial dispersion of repolarization (SDR), degenerate into ventricular fibrillation. However, most studies involving ventricular arrhythmias do not quantify SDR by means of an electrophysiological parameter. Therefore, we reviewed the effects of 4 highly effective anti-arrhythmic drugs (flunarizine, verapamil, SEA-0400, and GS-458967) on the repolarization duration and associated STV. All drugs were tested as anti-arrhythmic strategies against TdP in CAVB dogs, their high anti-arrhythmic efficacy was defined as suppressing drug-induced TdP in 100% of the experiments. This comparison demonstrates that even though the anti-arrhythmic outcome was similar for all drugs, distinct responses of repolarization duration and associated STV were observed. Moreover, the aforementioned and commonly adopted electrophysiological parameters were not always sufficient in predicting TdP susceptibility, and additional quantification of the SDR proved to be of added value in these studies. The variability in electrophysiological responses to the different anti-arrhythmic drugs and their inconsistent adequacy in reflecting TdP susceptibility, can be explained by distinct modes of interference with TdP development. As such, this overview establishes the separate involvement of temporal and spatial dispersion in ventricular arrhythmogenesis in the CAVB dog model and proposes SDR as an additional parameter to be included in future fundamental and/or pharmaceutical studies regarding TdP arrhythmogenesis.

Left bundle branch pacing utilizing three dimensional mapping.

INTRODUCTION: Permanent His bundle pacing is feasible and effective in patients with atrioventricular block or left bundle branch block. However, pacing thresholds to capture the distal His bundle is often higher. Recently left bundle branch area pacing (LBBP) has been shown to be feasible by advancing the lead transvenously, deep into the interventricular septum to reach the left ventricular endocardial surface. In this article we describe the utility of three dimensional (3D) mapping to achieve LBBP. METHODS: Ensite Precision (Abbott) mapping system was used to perform LBBP. A decapolar catheter was used to create 3D map of right atrium and right ventricle (RV). Regions of interest (His bundle, potential LBBP sites of interest in RV) were tagged in the 3D map. The LBBP lead was implanted utilizing the 3D map. The lead depth in the septum was assessed in the 3D map. RESULTS: LBBP was performed in three patients: chronic LBBB and intermittent 2:1 atrioventricular block; atrioventricular (AV) node ablation and conduction system pacing; and bifascicular block and intermittent AV block in a patient with severe left ventricular hypertrophy. LBBP was successful in all three patients. The lead depth in the interventricular septum was 12, 11, and 21 mm, respectively as assessed by 3D mapping. CONCLUSIONS: Three-dimensional mapping was helpful in achieving LBBP in patients with LBBB, severe left ventricular hypertrophy or during AV node ablation. 3D mapping also facilitated easy assessment of lead depth during and after lead fixation. 3D mapping techniques may be a valuable tool to reduce the learning curve of implanters with minimal experience in LBBP.

Carditis in Acute Rheumatic Fever in a High-Income and Moderate-Risk Country.

OBJECTIVE: To describe clinical presentation, electrocardiographic, and echocardiographic characteristics of carditis at the time of diagnosis of acute rheumatic fever (ARF) over a 13-year period. STUDY DESIGN: A single-center retrospective chart analysis was conducted involving all consecutive patients diagnosed with ARF between 2003 and 2015. Patient age, sex, clinical characteristics, recent medical history for group A streptococcal pharyngotonsillitis and antibiotic treatment, and laboratory, echocardiographic, and electrocardiographic findings were recorded. RESULTS: Of 98 patients (62 boys, mean age 8.81 ± 3.04 years), 59 (60.2%) reported a positive history of pharyngotonsillitis; 48 (49%) had received antibiotic (mean duration of treatment of 5.9 ± 3.1 days), and, among these, 28 (58.3%) had carditis. Carditis was the second most frequent finding, subclinical in 27% of patients. Mitral regurgitation was present in 49 of 56 patients (87.5%) and aortic regurgitation in 36/56 (64.3%) no stenosis was documented. CONCLUSIONS: ARF is still present in high-income countries and can develop despite primary prophylaxis, especially when given for a short course. Our findings highlight the need for 10 days of antistreptococcal treatment to prevent ARF. Echocardiography is important because 27% of cases with carditis were subclinical.

Deep Negative Deflection in Unipolar His-Bundle Electrogram as a Predictor of Excellent His-Bundle Pacing Threshold Postimplant.

Background His-bundle pacing (HBP) is a physiological form of pacing. Although high capture thresholds are common, few predictors of low HBP threshold have been determined. We aimed to identify electrophysiological predictors. Methods Fifty-one patients (53% with atrioventricular block) underwent HBP for bradycardia with an intrinsic QRS duration of <120 ms. Attempts to anchor the HBP lead were guided by unipolar His-bundle electrograms (HB EGMs) recorded with an electrophysiology recording system. Patients were followed-up for >6 months. Results In total, 153 attempts at anchoring the HBP lead were made, of which, 45 achieved acceptable HBP thresholds (≤2.5 V at 1 ms). The amplitude of negative deflection in HB EGM and the selective HBP form at fixation were independently associated with achieving an acceptable threshold. A negative amplitude of ≥0.060 mV in HB EGM was determined as the optimal value for identifying the acceptable threshold. This deep negative HB EGM was recorded with an HBP threshold of 1.4±1.3 V (in 34 attempts), significantly lower than that of positive HB EGM without deep negative deflection (2.8±1.3 V, in 31 trials; or >5 V, in 38 trials). The permanent HBP lead remained with deep negative (≥0.060 mV) or positive HB EGMs in 28 and 14 patients, respectively, and with positive or negative HB injury current in 19 and 23 patients, respectively. During follow-up, increased HBP threshold of >1 V was significantly more prevalent in the positive HB EGM group. The HBP thresholds of deep negative HB EGM and HB injury current, but not of the selective HBP group, were significantly lower than the other subgroups during follow-up. Conclusions Deep negative HB EGM at fixation was associated with an excellent short-term HBP threshold, similar to HB injury current. Analysis of unipolar HB EGM postfixation may enable prediction of permanent HBP threshold.

The characteristics of the electrocardiogram and the intracardiac electrogram in left bundle branch pacing.

INTRODUCTION: Left bundle branch pacing (LBBP) has recently been reported to maintain left ventricular electrical synchrony with a low and stable threshold. However, the electrocardiogram (ECG) definitions of LBBP have not been well established. We report four cases to show the characteristics of the ECG and the intracardiac electrogram (EGM) in LBBP. METHODS AND RESULTS: Four patients, two with an atrioventricular block (AVB) and two with left bundle branch block (LBBB), were included in the study. LBBP was performed and the ECGs and EGMs were collected and compared at different pacing outputs. Selective LBBP (S-LBBP) was defined as only capturing the LBB with a typical RBBB morphology and a discrete component between the pacing stimulus and ventricular activation in the EGMs. While nonselective LBBP (NS-LBBP) captured both the LBB and the local myocardium, resulting in a narrow right bundle branch block (RBBB) morphology without the discrete component. The left bundle branch (LBB) potential was recorded in two cases during narrow QRS complex or LBBB correction by selective His bundle pacing and SLBBP (n = 3) was achieved. A constant and shortest stimulus to left ventricular activation time (LVAT) in LBBP was obtained at different pacing outputs. CONCLUSION: The ECG and EGM characteristics of LBBP can be summarized as: 1) RBBB pattern; 2) usually with the LBB potential; 3) SLBBP with specific ECG changes and a discrete component in EGM; and 4) with a constant and shortest stimulus to LVAT at different pacing outputs. Further studies are necessary to confirm these observations.