Unusual atrial pacing induced by type II far-field p-wave sensing in a patient with complete atrioventricular block.

An 88-year-old Japanese woman underwent DDD pacemaker (MicroPort KORA 250 DR, V lead: VEGA R52) implantation for complete atrioventricular block. A 12-lead electrocardiogram for a routine examination showed atrial pacing within the intrinsic P wave, followed by inhibition of ventricular pacing. Pacemaker interrogation revealed no abnormalities in the basic parameters; however, ventricular pacing was inhibited by far-field sensing of intrinsic atrial waves before atrial events; type II far-field P-wave sensing.

Belt-type electrocardiograph for diagnosing palpitation occurring only during high-intensity exercise in athletes.

Unlabelled: Belt-type ambulatory electrocardiograph (EV-201) is an arrhythmia diagnostic device that can record an electrocardiogram (ECG) for a maximum of 2 weeks. Here, we report the novel utility of EV-201 in detecting arrhythmias in two professional athletes. Treadmill exercise test and Holter ECG failed to detect arrhythmia because of insufficient exercise, electrocardiogram noise.

Prediction of PR interval prolongation after catheter ablation of incisional atrial tachycardia.

Unlabelled: A three-dimensional (3D) mapping system is safe and effective for catheter ablation of incisional atrial tachycardia (IAT). Prolongation of the PR interval is occasionally observed after this procedure. Although a first-degree atrioventricular block is typically benign, an excessively prolonged PR interval can indicate a worse prognosis.

Relationship between Effective Refractory Period and Inducibility of Atrial Fibrillation from the Superior Vena Cava after Pulmonary Vein Isolation.

In terms of the pulmonary vein (PV), atrial fibrillation (AF) patients have a shorter effective refractory period (ERP) than those without AF and a large dispersion of the ERP. Although the frequency of AF from the superior vena cava (SVC) was the highest among non-PV foci, the characteristics of the ERP in the SVC (SVC-ERP) were unclear. The purpose of this study was to elucidate the relationship between SVC-ERP and the inducibility of AF after PV isolation (PVI).

Influence of the right ventricular septum/free-wall boundary (hinge) on differentiation of the ventricular lead implantation site.

Background: The prognosis associated with right ventricular (RV) free-wall pacing is worse than that of septal pacing. Identification of the pacing site using a 12‑lead electrocardiogram (ECG) is controversial and may be influenced by ECG changes within the same septal or free-wall area. The relationship between the diagnostic capabilities of ECG and pacing sites has previously been qualitatively evaluated.

Relationship between device displacement distance toward the caudal side during standing and pocket position laterality.

Background: The displacement of cardiac implantable electronic devices (CIEDs) toward the caudal side during standing after CIED implantation could cause lead dislodgement. This study investigated the relationship between supine pocket position and standing CIEDs' displacement distance after the implantation.

Methods: After CIED surgeries performed at 2 hospitals between 2012 and 2020, 134 patients underwent postoperative chest x-rays in the supine and standing positions during hospitalization.

Heart failure caused by iatrogenic atrial septal defect after cryoballoon ablation for atrial fibrillation.

An 83-year-old man with no structural heart disease underwent pulmonary vein isolation (PVI) for symptomatic paroxysmal atrial fibrillation (AF). The PVI was successfully performed by cryoballoon ablation with a single transseptal puncture. A 12Fr deflectable sheath and an 8.

Incidence of out-of-hospital cardiac arrests and survival rates after 1 month among the Japanese working population: a cohort study.

Objectives: The prevention and improvement of the prognosis of out-of-hospital cardiac arrests (OHCAs) are important issues especially with respect to their social and economic significance in working populations. The age distribution of the working population in Japan is expected to change continually due to its ageing society and extension of retirement; however, few reports have examined the long-term condition of OHCA in the working population, defined by age. The aim of this study was to determine the incidence of OHCAs and the survival rates after 1 month, among the Japanese working population, defined by age, considering the changing age distribution.

Large discrepancy in optimal atrioventricular delay between sensed and paced atrial events in a pacemaker patient.

A 74-year-old man experienced complete atrioventricular (AV) block 2 days after catheter ablation for right atrial (RA) macroreentrant tachycardia. We performed DDD pacemaker implantation with atrial septal pacing because other sites of pacing threshold were not acceptable. The maximum left ventricular outflow tract velocity time integral was 15.

Accessory pathway ablation during atrial fibrillation in Ebstein anomaly.

An 84-year-old woman with type B Wolff-Parkinson-White (WPW) with Ebstein anomaly was admitted with heart failure. She had rapid wide QRS tachycardia due to accessory pathway (AP) conduction associated with atrial fibrillation (AF). Since transesophageal echocardiography before catheter ablation showed a left atrial thrombus, ablation was performed using a 3D mapping system under AF.

Adenosine revives catheter-induced mechanical blocks in radiofrequency ablation.

Adenosine can hyperpolarize the atrial action potential, which helps rapidly re-establish the membrane potential in ablated sites and unmask "dormant conduction." It has been reported that pharmacological agents, including adenosine, were unable to revive traumatized tissues. We present the first case of the catheter-induced mechanical block ("bump" phenomenon) that was unmasked with adenosine administration in the working myocardium of the superior vena cava.

RR interval variability in the evaluation of ventricular tachycardia and effects of implantable cardioverter defibrillator therapy.

Background: An implantable cardioverter defibrillator (ICD) is the most reliable therapeutic device for preventing sudden cardiac death in patients with sustained ventricular tachycardia (VT). Regarding its effectiveness, targeted VT is defined based on the tachyarrhythmia cycle length. However, variations in RR interval variability of VTs may occur.

Rate-dependent pacing failure after pacemaker implantation: Novel insights into the mechanism of using adenosine.

An 82-year-old woman received pacemaker implantation for sick sinus syndrome. Two days after the implantation, electrocardiography showed 2:1 atrial pacing failure, followed by a bradycardia-dependent increase in the atrial pacing threshold during a pacemaker examination. However, transient 1:1 atrial pacing capture recovered by adenosine triphosphate (ATP) administration, which was performed to evaluate the bradycardia-dependent pacing failure mechanism.

Prevention of serious air embolism during cryoballoon ablation; risk assessment of air intrusion into the sheath by catheter selection and change in intrathoracic pressure: An ex vivo study.

Introduction: One cause of cerebral infarction during cryoballoon ablation is the entry of air into a sheath due to the use of inappropriate catheters. It is known that the left atrial pressure of patients with obstructive sleep apnea syndrome can be negative. However, the effects of catheter selection and negative pressure changes in the sheath on air intrusion are not yet well understood.

Pacing From the Right Ventricular Septum and Development of New Atrial Fibrillation in Paced Patients With Atrioventricular Block and Preserved Left Ventricular Function.

Background: Whether pacing from the right ventricular (RV) septum improves prognosis is unclear. Furthermore, the clinical characteristics of patients who develop atrial fibrillation (AF) and cardiovascular events during long-term RV septal pacing have not been described.Methods and Results:We retrospectively evaluated the incidence of AF and cardiovascular events, including cardiac death, heart failure requiring hospitalization, or stroke, for a median of 4.

Outcomes of single- or dual-chamber implantable cardioverter defibrillator systems in Japanese patients.

Background: There are no criteria for selecting single- or dual-chamber implantable cardioverter defibrillators (ICDs) in patients without a pacing indication. Recent reports showed no benefit of the dual-chamber system despite its preference in the United States. As data on ICD selection and respective outcomes in Japanese patients are scarce, we investigated trends regarding single- and dual-chamber ICD usage in Japan.

Different characteristics of heart failure due to pump failure and bradyarrhythmia.

Background: Heart failure (HF) can be caused by left ventricular (LV) pump failure as well as by bradyarrhythmias. Hemodynamic differences between HF by LV pump failure and that by bradyarrhythmia have not been fully investigated. We hypothesized that HF by LV pump failure could be associated with both reduced cardiac output (CO) and increased LV filling pressure due to associated LV diastolic dysfunction, whereas HF by bradyarrhythmia could be associated with reduced CO but only modestly increased LV filling pressure due to the absence of LV diastolic dysfunction.

Pacing and sensing interference by air bubble surrounding the non-extended helix of intact active fixation lead.

Background: Active fixation pacing leads with silicon cylinder tips have been used for their safety and flexibility. Measurement of baseline sensing/pacing characteristics before fixation of helix helps to identify the optimal pacing site, but we encountered difficulties in making these measurements despite multiple attempts with the model LPA 1200M lead. To identify the cause and overcome this complication, we compared 4 different retractable active fixation lead models, which enabled baseline sensing/pacing measurements before extension of helix.

Atrial pacing site and atrioventricular conduction in patients paced for sinus node disease.

Background: Unnecessary ventricular pacing in sinus node disease (SND) must be avoided. To test the hypothesis that in SND, with or without 1st degree atrioventricular (AV) block, cumulative percent ventricular pacing (cum%VP) can be limited by low right atrial septal (LRAS) instead of right atrial appendage (RAA) pacing.

Methods: We studied 102 dual-chamber pacemaker recipients with SND.