The Characteristics of spontaneous action potential of cardiac myocyte in rabbit pulmonary vein

학위논문(박사)--서울대학교 대학원 :의학과 내과학전공,2000.Docto

Radiofrequency induced lesion characteristics according to force-time integral in experimental model.

Contact force (CF)-sensing technology has enabled accurate real-time CF measurement in tissue. Average CF, which is quantified by the force?time integral (FTI), correlates with lesion volume. Little is known about which of the time and force factors that compose FTI plays a more important role and which is a better index for predicting lesion size, FTI, or force?power?time index (FPTI). Investigators sought to identify a better index for predicting radiofrequency ablation lesion formation with experimental model. Radiofrequency current was delivered to the swine skeletal muscle at radiofrequency energy current was delivered at 4 fixed power settings (15, 25, 30, and 40 W) for 6 variable time durations (5, 10, 20, 30, 40, and 50 s) with 6 variable CF settings (5, 10, 20, 30, 40, and 50 g). At each setting, the following parameters were evaluated: (1) transmural lesion depth, (2) lesion width, and (3) lesion volume. Between FTI factors, the time factor was more important than the force factor for lesion formation. The area under the curve was greater for FPTI (0.943) than for FTI (0.870). On univariate linear regression analysis, the explanatory power of the linear regression model was better explained by FPTI (56.4%) than FTI (32.1%). Under the same FTI condition, the time factor had a greater effect on lesion formation. When power was included, the power factor had a greater effect on lesion formation and steam pop

The shape of the left lateral ridge as a predictor of long-term outcome of catheter ablation for atrial fibrillation based on clinical and experimental data

Background: The left lateral ridge (LLR) is an important structure for ablation of atrial fibrillation (AF). This study assessed how the LLR shape is associated with the long-term outcomes of AF ablation and investigated the relationship with radiofrequency (RF) lesion formation. Methods and results: Clinical study - we assessed multi-detector computed tomography (MDCT) images in 247 patients who underwent AF ablation. Patients were classified into two groups according to the shape of the LLR: Narrow LLR group (n = 116; 47%) and Wide LLR group (n = 131; 53%). After a follow-up period 475 +/- 245 days, the AF-free rate was significantly higher in the wide LLR than Narrow LLR group (832% vs. 62.9%, p = 0.0004). A multivariate analysis showed that the shape of the LLR was an independent predictor of AF recurrence after ablation (hazard ratio 258; 95% confidential interval= 1.48-451, p = 0.001). Experimental study - Two types of the ridge models were made with porcine atrial tissues: "Narrow ridge(4.2 +/- 0.9 mm)" and "Wide ridge(9.7 = 1.8 mm)" RF ablation was performed on each ridge model using a contact force (CF)-sensing catheter. The mean CF and the RF lesion volume of the narrow ridge were significantly less than those of the wide ridge model (5.42 +/- 3.13 g vs. 10.37 +/- 3.98 g, p = 0.001; 19.8 +/- 9.9 mm(3) vs. 44.2 +/- 13.6 mm(3), p <0.001, respectively). Conclusions: AF recurrence after ablation was more frequent in patients with a narrow LLR. LLR shape as assessed using MDCT is associated with long-term outcomes after AF ablation. CF and lesion formation data using the porcine atrial tissue model support our clinical results. (C) 2020 Elsevier B.V. All rights reserved

Relation of Left Atrial Enlargement to Subsequent Thromboembolic Events in Nonvalvular Atrial Fibrillation Patients With Low to Borderline Embolic Risk

The current thromboembolic risk stratification of non-valvular atrial fibrillation (NVAF) does not include parameters from transthoracic echocardiography (TTE). We hypothesized that left atrial enlargement (LAE) on TTE could discriminate who require anticoagulation therapy among NVAF patients with low/borderline clinical embolic risk. This single-center cohort study included 6,602 patients with NVAF (median age, 56 years, 70.0% male) with a low to borderline clinical embolic risk (CHA(2)DS(2)-VASc score: 0 to 1 in males, 1 to 2 in females). LAE was classified as mild (>= 41 mm in males; >= 39 mm in females) or moderate-severe (>= 47 mm in males; >= 43 mm in females). The main study outcome was thromboembolic event (ischemic stroke and systemic embolism). Mild and moderate-severe LAE was diagnosed in 26.1% and 32.9% of the cohort, respectively. The patients with moderate-severe LAE showed a higher prevalence of baseline comorbidities and valvular heart disease and had a higher incidence of thromboembolic events than patients with mild or no LAE at 2 years of follow-up (2.5% vs 1.3% vs 1.1%, respectively, p < 0.001). After multivariable adjustment, patients with moderate-severe LAE were at a higher risk of thromboembolic event (hazard ratio, 2.54; 95% CI, 1.65 to 3.90; p < 0.001) compared to those with no LAE. This result persisted in a subgroup analysis of anticoagulant-nayve patients. The rate of thromboembolic events in patients with low clinical embolic risk and moderate-severe LAE was not different to those with high clinical embolic risk without LAE. In conclusion, Moderate-severe LAE on TTE was a significant predictor of thromboembolic events in NVAF patients at low/borderline clinical embolic risk. (C) 2020 Elsevier Inc. All rights reserved

Esophageal Thermal Injury after Catheter Ablation for Atrial Fibrillation with High-Power (50 Watts) Radiofrequency Energy

Background and Objectives: Data regarding the safety of atrial fibrillation (AF) ablation using high-power (50 W) radiofrequency (RF) energy in Asian populations are limited. This study was conducted to evaluate the incidence and pattern of esophageal injury after high-power AF ablation in an Asian cohort. Methods: We searched the prospective AF ablation registry to identify patients who underwent AF ablation with 50 W RF energy using the smart touch surround flow catheter (Biosense Webster, Diamond Bar, CA, USA). Visitag (TM) (Biosense Webster) was used for lesion annotation with predefined settings of catheter stability (3 mm for 5 seconds) and minimum contact force (50% of time >5 g). All patients underwent upper gastrointestinal endoscopy at 1 or 3 days after the ablation. Results: A total of 159 patients (mean age: 63 +/- 9 years, male: 69%, paroxysmal AF: 45.3%, persistent AF: 27.7%, long-standing persistent AF: 27.0%) were analyzed. Initially, 26 patients underwent pulmonary vein isolation with 50 W for 5 seconds at each point. The remaining 133 patients underwent prolonged RF duration (anterior 10 seconds and posterior 6 seconds). The incidence rates of esophageal erythema/erosion and superficial ulceration were 1.3% for each type of the lesion. Food stasis, a suggestive finding of gastroparesis, was observed in 25 (15.7%) patients. There were no cases of cardiac tamponade, stroke, or death. Conclusions: In Asian patients, AF ablations using 50 W resulted in very low rates of mild esophageal complications

Pacemaker dependency after transcatheter aortic valve replacement compared to surgical aortic valve replacement

Transcatheter aortic valve replacement (TAVR) is a standard treatment indicated for severe aortic stenosis in high-risk patients. The objective of this study was to evaluate the incidence of pacemaker dependency after permanent pacemaker implantation (PPI) following TAVR or surgical aortic valve replacement (SAVR) and the risk of mortality at a tertiary center in Korea. In this retrospective study conducted at a single tertiary center, clinical outcomes related to pacemaker dependency were evaluated for patients implanted with pacemakers after TAVR from January 2012 to November 2018 and post-SAVR from January 2005 to May 2015. Investigators reviewed patients' electrocardiograms and baseline rhythms as well as conduction abnormalities. Pacemaker dependency was defined as a ventricular pacing rate > 90% with an intrinsic rate of <40 bpm during interrogation. Of 511 patients who underwent TAVR for severe AS, 37(7.3%) underwent PPI after a median duration of 6 (3-7) days, whereas pacemakers were implanted after a median interval of 13 (8-28) days post-SAVR in 10 of 663 patients (P < .001). Pacemaker dependency was observed in 36 (97.3%) patients during 7 days immediately post-TAVR and in 25 (64.9%) patients between 8 and 180 days post-TAVR. Pacemaker dependency occurred after 180 days in 17 (50%) patients with TAVR and in 4 (44.4%) patients with SAVR. Twelve (41.4%) patients were pacemaker-dependent after 365 days post-TAVR. Pacemaker dependency did not differ at 6 months after TAVR vs SAVR. In patients undergoing post-TAVR PPI, 58.6% were not pacemaker-dependent at 1 year after the TAVR procedure