Akio Chikata

Optimal Force-Time Integral for Pulmonary Vein Isolation According to Anatomical Wall Thickness Under the Ablation Line.

Background Low contact force and force–time integral (FTI) during catheter ablation are associated with ineffective lesion formation, whereas excessively high contact force and FTI may increase the risk of complications. We sought to evaluate the optimal FTI for pulmonary vein (PV) isolation based on atrial wall thickness under the ablation line. Methods and Results Contact force parameters and FTI during anatomical ipsilateral PV isolation for atrial fibrillation and atrial wall thickness were assessed retrospectively in 59 consecutive patients for their first PV isolation procedure. The PV antrum was divided into 8 segments, and the wall thickness of each segment under the ablation line was determined using multidetector computed tomography. The FTI for each ablation point was divided by the wall thickness of the PV antrum segment where each point was located to obtain FTI/wall thickness. In total, 5335 radiofrequency applications were delivered, and 85 gaps in PV isolation ablation lines and 15 dormant conductions induced by adenosine were detected. The gaps or dormant conductions were significantly associated with low contact force, radiofrequency duration, FTI, and FTI/wall thickness. Among them, FTI/wall thickness had the best prediction value for gaps or dormant conductions by receiver operating characteristic curve analysis. FTI/wall thickness of <76.4 gram‐seconds per millimeter (gs/mm) predicted gaps or dormant conductions with sensitivity (88.0%) and specificity (83.6%), and FTI/wall thickness of <101.1 gs/mm was highly predictive (sensitivity 97.0%; specificity 69.6%). Conclusions FTI/wall thickness is a strong predictor of gap and dormant conduction formation in PV isolation. An FTI/wall thickness ≈100 gs/mm could be a suitable target for effective ablation.

Chronic Ischemia Induced by Woven Coronary Artery Anomaly with Typical Atrial Flutter: Insights from Multiple Imaging Devices

A 75-year-old man with a 120-bpm tachycardia and typical atrial flutter was admitted. Echocardiography showed a dilated left ventricle with anterior and apical wall akinesia. Tachycardia was terminated with cavotricuspid isthmus ablation. Multiple imaging findings revealed a woven coronary artery anomaly (WCAA) in the left anterior descending artery. Stress myocardial perfusion imaging was performed after ablation in the sinus rhythm and revealed stress-induced ischemia and a fixed low uptake in the WCAA territory. WCAA is generally regarded as a benign condition; however, compromised blood flow within the anomaly, caused by tachycardia-related diastolic shortening, may induce ischemia.

Impact of left atrial size on isolation area in the acute phase of pulmonary vein isolation using 28 mm cryoballoon

The impact of left atrial (LA) size on isolation area (ISA) using a 28‐mm second‐generation cryoballoon (CB) in the acute phase after pulmonary vein isolation (PVI) and the differences of CB from contact force‐guided radiofrequency (RF) ablation have not been fully investigated.

Optimal lesion size index to prevent conduction gap during pulmonary vein isolation: KANAMORI et al.

A novel real‐time lesion size index (LSI) that incorporates contact force (CF), time, and power has been developed for safe and effective catheter ablation. The optimal LSI was evaluated to eliminate gap formation during pulmonary vein isolation (PVI).

Adaptive cardiac resynchronization therapy for dilated cardiomyopathy with functional mitral regurgitation

We report the case of a man in his 60s who had dilated cardiomyopathy with severe functional mitral regurgitation. Four years after a cardiac resynchronization therapy (CRT) device with an implantable cardioverter defibrillator was implanted, this device was replaced with an adaptive CRT device because of battery consumption. Seven months after replacement of this device, the left ventricular pacing to right ventricular activation and the atrioventricular delay from automatic adjustments contributed to less functional mitral regurgitation. The findings from our case suggest that optimal CRT, by measuring intracardiac conduction parameters, is effective for functional mitral regurgitation.

Separated right and left ventricular excitation during right ventricular septal pacing in a patient with narrow QRS wave: a case report.

IntroductionRight ventricular septal pacing is thought to be better than right ventricular apical pacing for shortening the QRS duration and for preserving left ventricular function. However, right ventricular septal pacing may not be effective in all cases. In this case report, we present a rare case in which right ventricular septal pacing induced thoroughly separated right and left ventricular excitation despite the presence of a relatively narrow QRS wave during atrium-only pacing.Case presentationWe report a case of 63-year-old Japanese man with cardiomyopathy with an implantable cardioverter defibrillator placement for ventricular tachycardia. Three years after implantation, he developed second-degree atrio-ventricular block. Therefore, atrio-ventricular sequential pacing was started; then his heart failure was much worsened. His electrocardiogram showed a dissociated biphasic QRS wave during right ventricular high-septal pacing, despite the presence of a non-fragmented QRS morphology during atrium-only pacing. An activation map during right ventricular high-septal pacing showed that right ventricular conduction started at the pacing site and ended at the right ventricular basal inferior site. Subsequently after a 10ms interval, left ventricular conduction started at the left ventricular posteroseptum and ended at the left ventricular lateral wall. These data indicate that during right ventricular high-septal pacing, the first component of the QRS wave supposedly reflects only right ventricular excitation and the second component only left ventricular excitation. Also due to the intracardiac electrograms, it was assumed that this phenomenon was caused by transversely limited severe transseptal conduction disturbance.ConclusionIt should be noted that even ventricular septal pacing could evoke harmful interventricular dyssynchrony due to transversely limited severe septal conduction disturbance, despite the presence of a relatively narrow QRS wave.

Magnetic resonance imaging in a patient with an implantable cardiac defibrillator

A 58‐year‐old man, in whom an implantable cardiac defibrillator (ICD) had been implanted for Brugada syndrome, suffered rapidly progressive general paralysis. Various diagnostic imaging techniques were performed, but the cause could not be determined. Magnetic resonance imaging (MRI) scanning was performed. A 1.5‐Tesla MRI system was used, and the ICD was programmed to ODO mode and all tachycardia detection was turned off. MRI was performed safely under electrocardiogram and pulse oximeter monitoring, and appropriate precautions were taken in preparation for an emergency. ICD parameters did not change in post‐imaging investigations. MRI revealed an apparent tumor in the patients medulla and upper cervical spinal cord, which was diagnosed as high‐grade astrocytoma. When performing MRI procedures in patients with an ICD under urgent conditions, it is necessary to have complete knowledge of the procedure and to make careful preparations.