A case of repeated rate-dependent pacing threshold elevation after leadless pacemaker implantation.

The pacing threshold is important for leadless pacemakers, as the pacing output has a significant impact on battery longevity. Acute pacing rate-dependent threshold increases have also been reported with leadless pacemakers. In the present case, we experienced a case in which the threshold, which had been raised in the acute phase, once showed a tendency to improve, but then worsened again. And, as in previous reports, thresholds improved completely in the chronic phase. Repeated retrieval and reimplantation of leadless pacemakers increases the likelihood of fatal complications, so being aware of such phenomenon may prevent unnecessary procedure and complications.

Effective ablation of atrial tachycardia with an epicardial circuit-insights from endocardial scars sites: a case study.

A previous study reported primary macroreentrant atrial tachycardia (AT) in the left atrium (LA), including the epicardial circuit on a left atrial anterior wall (LAAW) scar, without any prior cardiac intervention (Miyazawa et al. in J Cardiovasc Electrophysiol 2019; 30: 263-264). However, determining the target for terminating macroreentrant ATs is challenging. The mapping revealed a centrifugal pattern but did not fully elucidate the AT circuit. The reentrant mechanism of these ATs was confirmed using entrainment pacing. The earliest excitation site (EES) was traditionally selected as the ablation site, typically located in healthy tissue. However, our two cases provide new insights into AT termination, including the epicardial bridge across the endocardial LAAW scar, using minimum ablation points, without the need to ablate the healthy EES.

Acute impact of atrial fibrillation on pacemaker lead-induced tricuspid regurgitation: Case report.

We report a case of worsening lead-induced tricuspid regurgitation (TR) after new-onset atrial fibrillation (AF) evaluated using three-dimensional (3D) transthoracic echocardiography (TTE) from admission through TR improvement. An 84-year-old man experienced worsening lead-induced TR with new-onset AF, acutely resulting in low output syndrome. Less invasive interventions, such as rhythm control therapy and diuretics administration worked effectively. However, 3DTTE revealed consistent restricted motion of the septal leaflet with lead impingement. Right heart dilatation due to AF and worsened TR led to incomplete closure of other leaflets and tricuspid annular dilatation, which caused further deterioration of the TR. According to the course of our case, new-onset AF can cause acute worsening of lead-induced TR and low output syndrome in patients with cardiac implantable electronic devices (CIED). Our findings emphasize the importance of understanding the TR etiology in patients with CIED, which may prevent unnecessary CIED lead extraction. Learning objective: Lead-induced tricuspid regurgitation (TR) can acutely deteriorate after new onset of atrial fibrillation (AF). AF-induced deterioration of TR may not depend on restricted motion of a leaflet with lead impingement but on incomplete closure of other leaflets caused by right heart and tricuspid annular dilatation. Rhythm control therapy and diuretics administration may improve AF-induced deterioration of lead-induced TR, and should be considered before performing invasive lead extractions.

Is narrowest QRS the best? A case of cardiac resynchronization therapy in a patient with left anterior fascicular block.

The efficacy of cardiac resynchronization therapy (CRT) in patients with a narrow QRS duration has not been established. We present a patient with a narrow QRS duration and left anterior fascicular block in which CRT was effective. Left ventricular lead implantation at the optimal site and appropriately-timed left ventricular pacing (LVP) resulted in left ventricle reverse remodeling. Left ventricular dyssynchrony did not improve with LVP at a timing that resulted in narrower QRS than an intrinsic QRS duration. The optimization of LVP timing in CRT for patients with a narrow QRS duration is discussed.

Achievement rate and learning curve of left bundle branch capture in left bundle branch area pacing procedure performed to demonstrate output-dependent QRS transition.

INTRODUCTION: Recently, output-dependent QRS transition was reported to be required to confirm left bundle branch (LBB) capture in LBB area pacing (LBBAP) procedure. This study aimed to evaluate the achievement rate and the learning curve of LBB capture in LBBAP procedure performed with the goal of demonstrating output-dependent QRS transition, and investigate predictors of LBB capture. METHODS AND RESULTS: The LBBAP procedure was performed in 126 patients with bradyarrhythmia. LBB capture was defined as a demonstration of output-dependent QRS transition. The following pacing definitions were used for evaluation: (1) LBBAP, which met the previously reported LBBAP criteria, (2) LBB pacing (LBBP), LBB capture was confirmed, and (3) available LBBP, LBB threshold was clinically usable (<3 V at 0.4 ms). The learning curve was evaluated by division into three time-periods. The achievement rates of LBBAP, LBBP, and available LBBP were 88.1%, 41.2%, and 35.7%, respectively. The achievement rates of all three pacing definitions significantly increased with experience (p < .01), but the achievement rate of available LBBP was still 50% in the third period. As predictors of LBB capture, the interval between LBB-Purkinje potential and QRS onset ≥22 ms had high specificity of 98.3%, while R wave peak time in V6 < 68 ms had insufficient sensitivity of 79% and specificity of 68%. CONCLUSION: Even if LBB capture was aimed in LBBAP procedure, it was not easy to achieve, and there was a clear learning curve. Much of LBBAP may be left ventricular septal pacing that does not capture LBB.

Severe sphincter of Oddi spasm after cryoballoon ablation: a case report of an unusual complication after atrial fibrillation ablation.

BACKGROUND: Perioesophageal vagal nerve (VN) injury after atrial fibrillation (AF) ablation remains an important complication. The VN provides parasympathetic innervation to the majority of the abdominal organs-including the stomach and the sphincter of Oddi (SO)-and regulates smooth muscle contraction. We present an unusual case of SO spasm induced by VN injury after cryoballoon ablation (CBA). CASE SUMMARY: A 71-year-old woman presented to our institution with paroxysmal AF. The patient had a history of cholecystectomy and SO dysfunction. She had undergone CBA for AF. Immediately after the procedure, the patient developed epigastric pain. Computed tomography showed dilation of the intra- and extrahepatic bile ducts, with the diameter of the common bile duct measuring ∼15.6 mm. Blood tests on postoperative Day 1 revealed severely elevated aminotransferase levels (aspartate aminotransferase, 3156 U/L; alanine aminotransferase, 2084 U/L; lactate dehydrogenase, 2279 U/L; total bilirubin 1.7 mg/dL). DISCUSSION: It is known that VN denervation induces SO spasms. The right and left vagal trunks descend alongside the oesophagus, forming a perioesophageal plexus and innervating most of the gastrointestinal organs. In our case, SO spasm was induced as a result of the perioesophageal plexus injury caused by CBA. Underlying SO dysfunction and post-cholecystectomy also played an important role. Coupled with the absence of the gallbladder, which is the reservoir of bile juice and coordinator of SO, SO spasm caused severe elevation of the bile duct pressure. Care should be taken when performing AF ablation with regards to the stomach and the SO.

Differences in the durability of left atrial posterior wall isolation based on the isolation process.

PURPOSE: The best strategy for durable left atrial posterior wall isolation (PWI) after completion of pulmonary vein isolation (PVI) is not yet determined. This study aimed to examine the differences in the durability of PWI based on the isolation process and the predictors of the reconduction of PWI. METHODS: Among the 221 patients (mean age, 65 ± 11 years) with consecutive non-paroxysmal atrial fibrillation (AF) who completed PVI and PWI, 50 patients undergoing repeat AF ablation were enrolled and divided into the following groups based on how PWI was achieved at the initial procedure: by only the first line on the roof and floor line (group A), by additional gap ablation to the first line or second liner ablation next to the first line (group B), and by adjunct ablation inside the PW revealing the earliest activation (group C). RESULTS: Reconduction of PWI occurred in 24 of the 50 patients (48%). The durability of PWI in groups A, B, and C was 81% (17 of 21 patients), 75% (6 of 8 patients), and 14% (3 of 21 patients), respectively (p < 0.01). In a multivariate analysis, the ablation inside the PW for PWI was the independent predictor of the reconduction of PWI (p < 0.001). CONCLUSION: PWI achieved by the ablation inside the PW resulted in a high rate of reconduction. It may be necessary to aim to achieve the PWI without ablating the inside of the PW to prevent reconduction.

Bachmann's bundle-ridge related biatrial tachycardia with a long epicardial circuit.

Biatrial tachycardia (BiAT), involving Bachmann's bundle in the circuit, has sometimes been observed after mitral anterior line ablation. In this article, we present a case of BiAT, involving a long epicardial circuit, composed of Bachmann's bundle and the left atrial ridge (LAR). We discuss the optimal ablation technique for this tachycardia based on our experience in addition to the relationship between Bachmann's bundle and the LAR. Furthermore, the evaluation method for the mitral anterior block line is also discussed.

Characteristics and proposed mechanisms of QRS morphology observed during the left bundle branch pacing procedure.

BACKGROUND: In performing left bundle branch pacing (LBBP), various QRS morphologies are observed as the lead penetrates the ventricular septum (VS). This study aimed to evaluate these characteristics and infer the mechanism underlying each QRS morphology. METHODS: In 19 patients who met the strict criteria for LBB capture, we classified the QRS morphologies observed during the LBBP procedure into seven patterns, the first five of which were determined by the depth of penetration: right ventricular septal pacing (RVSP), intraventricular septal pacing (IVSP1 and IVSP2), endocardial side of left ventricular septal pacing (LVSeP), nonselective LBBP (NS-LBBP), selective LBBP (S-LBBP), and NS-LBBP with anodal capture. The parameters of the QRS morphologies in these seven patterns were evaluated. RESULTS: Among the first five patterns, stimulus-QRSend duration (s-QRSend) was the narrowest in IVSP1 rather than in NS-LBBP, and stimulus-to-peak of R wave in V6 (s-LVAT) was significantly shortened in two steps, from RVSP to IVSP1 (96 ± 11; 82 ± 8 ms, p < .01) and from LVSeP to NS-LBBP (76 ± 7; 60 ± 4 ms, p < .01). The late-R duration in V1 was significantly prolonged in the order of LVSeP, NS-LBBP, and S-LBBP (45 ± 7; 53 ± 10; 71 ± 15 ms, respectively, p < .01). CONCLUSIONS: s-QRSend was the narrowest in IVSP1 rather than in NS-LBBP among the QRS morphologies observed during lead penetration through the VS. The prolonged late-R duration in V1 and abrupt shortening of the s-LVAT in V6 may help determine LBB capture during lead penetration.

Absence of shock therapy related to improper sensing of noise on the defibrillation test during subcutaneous implantable cardioverter-defibrillator implantation: a case report.

BACKGROUND: Subcutaneous implantable cardioverter-defibrillator (S-ICD) represents an efficient alternative to transvenous ICD in patients who do not require pacing. The intraoperative defibrillation test (DFT) is recommended during S-ICD implantation to confirm appropriate sensing and successful 65-J termination of induced ventricular fibrillation (VF). However, few cases of oversensing of noise inhibiting therapies have been reported. CASE SUMMARY: We report the case of a 50-year-old man who underwent S-ICD implantation for secondary prevention of sudden cardiac death. Immediately after S-ICD implantation, VF was induced using a 50-Hz burst; however, shock was not delivered owing to sustained noise on the electrogram in the primary vector. Therefore, an external rescue shock was needed at 150 J. We changed the sensing vector from primary to secondary and performed a second DFT. The S-ICD could deliver an appropriate shock and was able to successfully terminate VF without noise markers in the secondary vector. During the second DFT, one back-up pacing was delivered after the shock; the sensing vector then automatically switched from the secondary to the alternate vector. However, noise was observed in the alternate vector despite sinus rhythm restoration. DISCUSSION: The present case demonstrated that noise was recorded in two different vectors during DFT, possibly supporting the hypothesis that the muscle spasm of the diaphragm induced by the 50-Hz burst causes oversensing of noise by the S-ICD.

Synthesis of Pd-Ru solid-solution nanoparticles by pulsed plasma in liquid method.

We have synthesized solid-solution nanoparticles (Pd : Ru = 1 : 3, 1 : 1 and 3 : 1) in an immiscible Pd-Ru system by the pulsed plasma in liquid method using Pd-Ru mixture bulk electrodes. The particle sizes of the floated and sedimented samples were measured to be <10 and <20 nm, respectively, via high-resolution transmission electron microscopy (HR-TEM). The lattice parameters of nanoparticles followed the Vegard's law, and the energy-dispersive X-ray spectroscopy (EDX) results almost coincided with those obtained for the starting bulk mixtures. The solid-solution structures and local structure were confirmed via HR-TEM, X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure spectroscopy (XAFS).

Successful catheter ablation improves exercise tolerance in persistent atrial fibrillation patients, especially those with reduced ventricular contraction, preserved atrial function, or a high CHADS2 score.

BACKGROUND: It has been reported that rhythm control for persistent atrial fibrillation (per-AF) patients by catheter ablation improves their exercise tolerance, subjective symptoms, and quality of life (QoL). However, clinical factors that can predict future improvement of exercise capacity after successful catheter ablation in per-AF patients are unclear. METHODS: This study consisted of 62 patients (mean age 65.6 ±â€¯8.7 years, 77% males) with per-AF who underwent catheter ablation from June 2017 to May 2018. All patients were subjected to extended pulmonary vein isolation. Exercise tolerance was evaluated using a symptom-limited cardiopulmonary exercise test before and 3 months after catheter ablation. Primary endpoints were QoL measurements using an original questionnaire and functional assessments performed at 3 months. RESULTS: The questionnaire revealed significant improvement in QoL after catheter ablation (minimal metabolic equivalents occurring symptoms: from 5.48 ±â€¯1.14 to 5.64 ±â€¯1.06; p = 0.01). Endurance exercise characteristics improved significantly after catheter ablation, demonstrated by a shift in anaerobic threshold (from 13.3 ±â€¯3.0 to 15.2 ±â€¯3.3 ml/kg/min; p < 0.001), peak oxygen uptake (from 19.1 ±â€¯4.6 to 22.5 ±â€¯5.0 ml/kg/min; p < 0.001), and minute ventilation vs carbon dioxide production slope (from 28.3 ±â€¯6.1 to 25.7 ±â€¯3.8; p < 0.001). Multivariate Cox regression analysis revealed that a decreased left ventricular ejection fraction, high left atrial appendage velocity, and high CHADS2 score were identified as independent predictors of anaerobic threshold and a peak value of oxygen uptake with more than 20% improvement. CONCLUSIONS: Catheter ablation for per-AF patients improves QoL and exercise tolerance. The effect was especially remarkable in patients with reduced ventricular function, those who had a preserved atrial function, or those at high risk of thromboembolism.

Prognostic value of high-sensitive troponin T for predicting cardiovascular events after atrial fibrillation ablation.

BACKGROUND AND OBJECTIVES: This study aimed to evaluate the utility of high-sensitive troponin T (hs-TnT) for predicting AF recurrence and major adverse cardiovascular events (MACE) after AF ablation. METHODS AND RESULTS: A total of 227 consecutive patients with AF (mean age, 66 ± 10 years; persistent AF, n = 98) who underwent an initial ablation were enrolled. We measured hs-TnT before AF ablation and divided the patients into three groups according to the hs-TnT level: low, lesser than or equal to 0.005 µg/L (n = 54); medium, 0.006-0.013 µg/L (n = 127); and high, greater than or equal to0.014 µg/L (n = 46). We evaluated the composite endpoint of AF recurrence or MACE (including death, stroke, acute coronary syndrome, and heart failure hospitalization) after the ablation. The median hs-TnT level was 0.008 µg/L. The values of chronic kidney disease prevalence, CHA2 DS2 -VASc score, B-type natriuretic peptide level, and left atrial diameter were the highest in the high hs-TnT group among the three groups. During a mean follow-up of 15 ± 8 months, AF recurrence and MACE occurred in 56 (25%) and 9 (4%) patients, respectively. The high hs-TnT group had the highest incidence of AF recurrence and MACE among the three groups (high: 39% and 15%, medium: 22% and 2%, and low: 19% and 0%, respectively; log-rank P < .05). In multivariate analysis, hs-TnT greater than or equal to 0.014 µg/L and persistent AF were independent predictors of the composite endpoint. CONCLUSION: Hs-TnT may be a useful marker for predicting AF recurrence or MACE after AF ablation.

Synthesis of Pd-Fe System Alloy Nanoparticles by Pulsed Plasma in Liquid.

We synthesized Pd-Fe series nanoparticles in solid solution using pulsed plasma in liquid with Pd-Fe bulk mixture electrodes. The Pd-Fe atomic percent ratios were 1:3, 1:1, and 3:1, and the particle size was measured to be less than 10 nm by high-resolution transmission electron microscopy (HR-TEM). The nanoparticles showed face-centered cubic structure. The lattice parameter increased with increasing Pd content and followed Vegard's law, and energy-dispersive X-ray spectra were consistent with the ratios of the starting samples, which showed a solid solution state. The solid solution structure and local structure were confirmed by HR-TEM and X-ray absorption fine structure.