Feasibility of a novel atrial mechanical sensing method for leadless atrioventricular synchronous pacing.

INTRODUCTION: Few studies have demonstrated a high degree of atrioventricular (AV) synchrony with a new leadless pacemaker called Micra AV. Our group previously reported a new and unique sensing method. We believe that this novel sensing method, "Simplified A3 method," might facilitate better AV synchrony than a conventional sensing method in almost all cases with Micra AV implantation. METHODS: We conducted a non-randomized retrospective study comparing the two pacing methods at two centers. From December 1, 2021 to October 31, 2022, Micra AV was implanted for 32 patients at the two centers. Twenty of the 32 patients with sinus rhythm and complete AV block were included in this study. In Group 1, the conventional setting was programmed as follows: auto A3 threshold, auto A3 window-end (WE), and auto A4 threshold turned on during hospitalization. In Group 2, the "Simplified A3 method" was programmed as follows: auto A3 threshold and auto A3WE turned off. Instead, an intentionally prolonged A3WE (850-1000 ms) and low A3 threshold (A3 signal amplitude + 0.5-1.0 m/s2) were programmed. RESULTS: Twenty patients were analyzed. In Group 2, AV synchrony (%AMVp) was significantly higher at the first outpatient clinic (63.0 ± 5.7% vs 81.0 ± 4.2%, p = .03). A3 threshold was significantly lower in Group 2 (5.9 ± 0.7 m/s2, p < .05 vs 2.3 ± 0.5 m/s2, p < .05). CONCLUSION: Our novel sensing method might be a more feasible sensing method for obtaining higher AV synchrony than the conventional algorithm.

Second Micra leadless pacemaker implantation by using intracardiac echocardiography.

The strategy after battery depletion was not established in Micra leadless pacemaker system (Micra). There are still some concerns in the 2nd Micra implantation, such as the mechanical interaction between both devices. The position of the 2nd Micra should be placed apart from the 1st Micra. We present a case of 1st Micra battery depletion who successfully underwent the 2nd Micra implantation under the intracardiac echo guidance. In our case, intracardiac echo was a very effective tool for confirming the location of Micra implantation.

A case of short-coupled variant of Torsade de Pointes with bystander early repolarization in inferior leads.

The presence of J waves in cases of ventricular fibrillation (VF) is known to be a risk for sudden cardiac death. Recently, the effectiveness of radiofrequency catheter ablation (RFCA) for early repolarization syndrome (ERS) has been reported.The patient is a 30-year-old male with elevated J waves of 0.1 mV in the inferior leads, who had previously developed VF and undergone implantable cardioverter defibrillator (ICD) implantation. Because the VF from short coupled premature ventricular contraction (PVC) was presented, the RFCA of the triggered PVC was attempted. But it was unsuccessful due to no inducibility of the triggered PVC. After that, despite anti-arrythmia drug treatment, appropriate ICD shock for VF was observed. Although we decided to do a second ablation and evaluated epicardial arrhythmia substrate, no specific findings of early repolarization syndrome were found in the electrophysiological study. Finally, we considered that the cause of VF was short-coupled variant of Torsade de Pointes, and PVC ablation was performed. VF has not occurred since. We consider that this is a rare case to evaluate the epicardial arrhythmogenic substrate of J wave. Learning objective: Ablation of the epicardial arrhythmogenic substrate in patients with early repolarization syndrome (ERS) has been shown to be effective, but the relationship between abnormal epicardial potentials and the pathophysiology is unclear. In this case, J-wave and epicardial delayed potentials were not considered to represent obvious arrhythmogenic substrates. Ablation of the triggered premature ventricular contraction may be effective in ERS without apparent abnormal potentials.

Primary Cardiac Lymphoma: A Lesson Learned from an Unsuccessful Experience.

A 79-year-old man was admitted because of complete heart block. Echocardiograms showed an abnormal mass adjacent to the sinus of Valsalva. Subsequent surgical resection was not successful. Despite chemotherapy, the patient died from multiple organ failure. It is important to recognize that approximately 80% of cases of cardiac lymphoma are diffuse large B-cell lymphoma, which is the only malignant neoplasm that may respond well to chemotherapy with rituximab. In order to save patients' lives, the early implementation of chemotherapy with rituximab is critical and should be considered as a therapeutic diagnostic option in select patients.

Right ventricular mobile thrombus in end-stage hypertrophic cardiomyopathy.

We report the first case of a mobile right ventricular apical thrombus in hypertrophic cardiomyopathy in the absence of right ventricular apical aneurysm. An 87-year-old man who had been diagnosed as having hypertrophic cardiomyopathy presented with gross peripheral edema and exertional dyspnea. He had been on warfarin, ß-blockade, and diuretics. Electrocardiograms indicated progression of the disease with atrial fibrillation, low voltage and prominent Q waves in the left precordial leads. Echocardiograms revealed ventricular septal and apical hypertrophy, hypokinetic distal left ventricle, and dilated and severely hypokinetic right ventricle. A mobile thrombus (18 mm × 18 mm) was detected in the right ventricular apex. Cardiac computed tomography and magnetic resonance imaging confirmed a large thrombus in the right ventricular apex. Late gadolinium enhancement was present in the interventricular septum and distal segments of both ventricles, indicating myocardial fibrosis and scar. A dilated and poorly contracting right ventricle, particularly right ventricular apex, in end-stage hypertrophic cardiomyopathy, associated with stagnant blood flow in the apex, was hypothesized as being responsible for right ventricular apical thrombus formation in the absence of right ventricular aneurysm. .