[Show abstract][Hide abstract] ABSTRACT: Background and objectives:
Identifying the critical isthmus of slow conduction is crucial for successful treatment of scar-related ventricular tachycardia. Current 3D mapping is not designed for tracking the critical isthmus and may lead to a risk of extensive ablation. We edited the algorithm to track the delayed potential in order to visualize the isthmus and compared the edited map with a conventional map.
Subjects and methods:
We marked every point that showed delayed potential with blue color. After substrate mapping, we edited to reset the annotation from true ventricular potential to delayed potential and then changed the window of interest from the conventional zone (early, 50-60%; late, 40-50% from peak of QRS) to the edited zone (early, 80-90%; late, 10-20%) for every blue point. Finally, we compared the propagation maps before and after editing.
We analyzed five scar-related ventricular tachycardia cases. In the propagation maps, the resetting map showed the critical isthmus and entrance and exit sites of tachycardia that showed figure 8 reentry. However, conventional maps only showed the earliest ventricular activation sites and searched for focal tachycardia. All of the tachycardia cases were terminated by ablating the area around the isthmus.
Identifying the channel and direction of the critical isthmus by a new editing method to track delayed potential is essential in scar-related tachycardia.
Preview · Article · Jan 2016 · Korean Circulation Journal
[Show abstract][Hide abstract] ABSTRACT: We hypothesized that continuous heparin infusions would be favorable for maintaining heparin concentrations during radiofrequency catheter ablation (RFCA) of atrial fibrillation (AF).
No preview · Article · Dec 2015 · JACC Clinical Electrophysiology
[Show abstract][Hide abstract] ABSTRACT: Background:
-Early recurrence (ER) of atrial tachyarrhythmias during the first three months (blanking period) after atrial fibrillation (AF) ablation can be highly symptomatic, often requiring emergency treatment. Short-term steroid therapy may suppress ER during the blanking period.
Methods and results:
-We prospectively enrolled 138 patients who were randomly assigned to two groups (steroid group and control group). An IV bolus of 0.5mg/kg of methylprednisolone for two days followed by 12mg daily of oral methylprednisolone for four days was given to the steroid group patients. The primary endpoint was ER during the blanking period (three months post-ablation). During the blanking period, 51 of the 138 (37.0%) patients experienced ER after AF ablation. The steroid group had a lower rate of ER than the control group (15/64 [23.4%] vs. 36/74 [48.6%], P=0.003). There was no difference between the two groups regarding late recurrence over a 24-month follow up (log rank test, P=0.918). In a multivariate analysis, short-term steroid therapy was independently associated with a lower rate of ER during the blanking period (adjusted OR 0.45, 95% CI 0.25-0.83, P=0.01).
-Periprocedural short-term moderate intensity steroid therapy reduces ER (~3 months) after catheter ablation of AF. It is not effective in preventing late (3~24m) AF recurrence.
Clinical trial registration:
-www.who.int/ictrp; Unique identifier:KCT0000107.
No preview · Article · Nov 2015 · Circulation Arrhythmia and Electrophysiology
[Show abstract][Hide abstract] ABSTRACT: Purpose
Although several studies have reported the morphological and electrical characteristics in patients with hypertrophic cardiomyopathy (HCM), comparison between asymmetric and apical HCM has not been investigated in a reasonably sized cohort.
Materials and Methods
Echocardiography and electrocardiography were quantitatively analyzed in patients with HCM in a Korean tertiary referral center.
Of 864 patients (mean age 55.4±14.2 years, 68.9% men), 255 (29.5%) patients had apical HCM, 553 (64.0%) patients asymmetric HCM, and 56 (6.4%) patients mixed type HCM. In echocardiographic evaluations, about three quarters of patients (75.8%) had left atrial enlargement. Left ventricular (LV) dilatations and systolic dysfunction were observed in 6.1% and 2.4%, respectively. QRS widening, PR prolongation, and pathologic Q wave are frequent in patients with asymmetric HCM, while LV strain is frequent in patient with apical HCM. The prevalence of J-point elevations (9.4% in inferior, 2.2% in lateral leads) were substantially higher than that in general population. Giant negative T wave was observed in 15.0% of total patients (32.2% in apical, 6.2% in asymmetric, 25% in mixed type). There was no significant correlation between the thickness of the apical wall and the amplitude of T wave inversion (r=-0.005, p=0.71).
In a large cohort of HCM including apical type, repolarization abnormalities, including early repolarization and QT prolongation as well as LV strain, were significantly observed. T wave inversion was not appropriate for screening of HCM and not correlated with apical wall thickness.
Preview · Article · Nov 2015 · Yonsei Medical Journal
[Show abstract][Hide abstract] ABSTRACT: Little is known about the long-term outcomes of catheter ablation of supraventricular tachycardia (SVT) using remote magnetic navigation system (RMN).
One hundred twenty patients underwent catheter ablation of SVTs with RMN (Niobe, Stereotaxis, USA): atrioventricular nodal re-entrant tachycardia (AVNRT; n = 59), atrioventricular re-entrant tachycardia (AVRT; n = 45), and focal atrial tachycardia (AT, n = 16). The outcome of AVRT with right free wall accessory pathway was compared with those of a group of 26 consecutive patients undergoing manual ablation.
Mean follow-up period was 2.2 ± 1.4 years. Overall arrhythmia-free survival was 86 %; AVRT (77 %), AVNRT (96 %), and focal AT (71 %). After the learning period (initial 50 cases), procedural outcomes had improved for AVRT and AVNRT (91 % in overall group, 90 % in AVRT group, 100 % in AVNRT group, and 68 % in focal AT group). The recurrence-free rate was higher for the free wall accessory pathways than those of the other sites (92 vs. 73 %, log-rank P = 0.06). Furthermore, when it is confined for the right free wall accessory pathway, RMN showed excellent long-term outcome (7/7, 100 %) compared to the results of manual approach (18/26, 69.2 %, log-rank P = 0.07).
RMN showed favorable long-term outcomes for the ablation of SVT. In our experience, RMN-guided ablation may be associated with a higher success rate as compared to manual ablation when treating right-sided free wall pathways.
No preview · Article · Mar 2015 · Journal of Interventional Cardiac Electrophysiology
[Show abstract][Hide abstract] ABSTRACT: Predictors of Torsades de Pointes (TdP) in bradyarrhythmia-induced acquired long QT syndrome (LQTS) are not well defined.Objective
This study looked for electrocardiographic TdP predictors in patients with acquired atrioventricular block (AVB) and QT prolongation.Methods
We analyzed 12-lead electrocardiograms(ECGs) from 20 patients (2.2%, 15 females, 65.9±15.6 years old) with TdP episodes out of 898 AVB patients in three tertiary hospitals. The ECG repolarization parameters in TdP patients were compared with those of 80 age- and sex-matched control AVB patients with no TdP episodes.ResultsTdP was initiated by premature ventricular complexes (PVCs) with a long-short sequence of activation. The average cycle length of the long sequence was 1289.9±228.9ms, and was 2.3±0.6 times longer than the cycle length of the short sequence. TdP patients had a significantly longer mean QT interval (716.4±98.9 vs. 523.2±91.3ms, p=0.001), mean T peak-to-end interval (334.2±59.1 vs. 144.0±73.7ms, p=0.001) and a higher Tpe/QT ratio (0.49±0.09 vs. 0.27±0.11, p=0.001) compared with non-TdP controls. TdP patients showed a higher prevalence of notched T waves in which T2 was at least 3mm taller than T1 (45.0% vs. 1.3%, p=0.001), triphasic T waves (30.0% vs. 1.3%, p=0.001), reversed asymmetry (20.0% vs. 0%, p=0.001), and T wave alternans (35.0% vs. 0%, p=0.001). An algorithm combining these morphological parameters was able to differentiate TdP patients from non-TdP patients with high sensitivity (85.0%) and specificity (97.5%).Conclusion
An algorithm combining specific T wave morphologies was useful to identify patients with AVB who are at risk of developing TdP.
[Show abstract][Hide abstract] ABSTRACT: Purpose
The selection of the optimal right ventricular (RV) pacing site remains unclear. We hypothesized that a normal paced QRS axis would provide a physiological ventricular activation and lead to a better long-term outcome.
We evaluated 187 patients who underwent a permanent pacemaker implantation and were dependent on RV pacing. The pacing sites were classified as the apex and non-apex according to the chest radiography. A paced QRS axis was defined as that between −30° and 90°. Preservation of the left ventricular (LV) systolic function was defined as that with a
No preview · Article · Nov 2014 · Journal of Interventional Cardiac Electrophysiology
[Show abstract][Hide abstract] ABSTRACT: Electrocardiographic markers identifying malignant forms of early repolarisation (ER) from ER of normal variants are of prime clinical importance. We compared the ECG parameters of ER patterns in patients with early repolarisation syndrome (ERS) proximate to the ventricular fibrillation (VF) episodes, remote from the events and those with normal controls with ER.
A retrospective, case-control study.
This study included 12 patients with ERS and 36 age-matched, gender-matched controls with ER.
Dynamic change of J-wave.
The highest amplitude of J-wave, sum of the J-wave amplitudes or the number of leads with ER showed a dramatic change during the perievent period. J-wave amplitudes (2.0±1.3 vs 4.0±1.7, p=0.004) and the number of leads with ER (3.3±1.7 vs 5.3±2.0, p=0.021) were significantly higher around the time of VF. In particular, the characteristic morphology of 'giant' (wide, >80 ms) J-waves were observed during the perievent period in 5/12 patients with ERS. However, there were no significant differences in the electrocardiographic parameters of ER pattern remote from VF events between the patients with ERS and normal control subjects with ER.
Although the extent of and amplitude of J-wave or ST segment elevation (STE) increased significantly around VF episodes, the electrocardiographic parameters of ER remote from VF episodes were not significantly different from those of normal controls. The narrow time window of these ECG changes limits early detection of ER patients at risk of developing VF or sudden cardiac death.
No preview · Article · Oct 2013 · Heart (British Cardiac Society)
[Show abstract][Hide abstract] ABSTRACT: Left anterior line (LAL) has been used as a substitute for mitral isthmus line for catheter ablation of chronic atrial fibrillation (AF). However, it results in left anterolateral conduction delay and might affect left atrial (LA) contractility. We aimed to investigate whether LAL decreases LA appendage function.
This study included 46 patients (30 men, mean age 58 ± 9 years, group 1) with persistent AF who underwent catheter ablation including LAL. Thirty patients with paroxysmal AF who received no additional LA ablation were compared as control group (21 males, mean age 56 ± 8 years, group 2). Transthoracic and transesophageal echocardiography with Doppler tissue imaging was performed in sinus rhythm before and after the ablation. We compared the following variables: (1) E/A ratio of the mitral flow velocity, (2) ratio of early mitral inflow and mitral septal annulus velocity (E/Em), (3) peak velocity of appendage outflow (ApVmax), and (4) time delay from QRS onset to appendage outflow (TDqa).
LA diameter was significantly reduced after ablation in both groups. In group 1, parameters for diastolic function (E/A ratio, 1.7 ± 0.5 vs 2.0 ± 0.6, P = 0.197; E/Em, 11.7 ± 4.8 vs 11.6 ± 5.1, P = 0.883) and appendage flow (ApVmax, 55.2 ± 19.9 cm/s vs 50.3 ± 19.3 cm/s, P = 0.203; TDqa, -77.3 ± 30.1 ms vs -66.1 ± 60.8 ms, P = 0.265) did not change significantly after ablation. Changes of ApVmax and TDqa after ablation were not significantly different between two groups (P = 0.409 and P = 0.195, respectively).
LAL ablation did not aggravate mitral flow pattern or change appendage outflow. LAL could be used without concern over worsening LA diastolic and appendage function.
No preview · Article · Sep 2013 · Pacing and Clinical Electrophysiology
[Show abstract][Hide abstract] ABSTRACT: Although apical hypertrophic cardiomyopathy (HCM) has been considered to be more benign than asymmetric HCM, few studies have directly compared their clinical features. We compared the electrocardiographic data and longterm outcomes between patients with apical HCM versus asymmetric HCM. This retrospective study enrolled 796 patients (243 apical HCM and 553 asymmetric HCM). We assessed long-term all-cause and cardiac mortalities using an inverse probability of treatment weighted (IPTW) method and propensity score matched (PSM) analysis. In patients with asymmetric HCM, QT prolongation, QRS widening, PR prolongation, and pathologic Q wave were significantly more frequent. The incidences of early repolarization were similar (11% in apical and 12% in asymmetric HCM, P = 0.19). The median follow-up duration was 6.5 years. There was a borderline significant difference in overall survival rates between the apical and asymmetric HCM groups (73% versus 69%, log rank P = 0.38, IPTW: P = 0.05, PSM: P = 0.05). Regarding cardiac death, asymmetric HCM was more hazardous than apical HCM (89% versus 77%, log rank P = 0.04, IPTW: P = 0.03, PSM: P = 0.03). There was no electrocardiographic predictor for the long-term outcomes, although beta-blocker use was significantly associated with lower overall death (HR = 0.58, 95% CI = 0.41-0.81) and slightly lower cardiac death (HR = 0.86, 95% CI = 0.55-1.33). The overall survival rate of apical HCM was as high as that of asymmetric HCM, but the cardiac survival rate was significantly lower in patients with asymmetric HCM. Beta-blocker use was associated with better long-term outcomes.
Preview · Article · Aug 2013 · International Heart Journal
[Show abstract][Hide abstract] ABSTRACT: Background:
Prompt diagnosis and management of atrial tachyarrhythmias (ATAs) during catheter ablation of atrial fibrillation (AF) is still challenging.
Methods and results:
In 88 patients undergoing catheter ablation of AF, 128 regular ATAs were induced or converted from AF. The coronary sinus activation time (CSAT) around the mitral annulus (MA) was measured as the difference in activation time between the most proximal and distal poles of the coronary sinus (CS) electrodes. Entrainment pacing was performed around the MA, roof area, or cavotricuspid isthmus (CTI) depending on the CSAT result. Mechanisms of tachycardias included macro-reentry around the MA (perimitral atrial flutter [PM-AFL], n=63), roof-dependent AFL (Roof-AFL, n=14), CTI-dependent AFL (CTI-AFL, n=25), and atrial tachycardia (AT, n=26). When the CSAT was ≥ 45 ms, the MA activation sequence was sequential, either proximal to distal or distal to proximal. When the CSAT was <45 ms, the MA activation sequence was mainly non-sequential with converging or diverging patterns. CSAT <45 ms was highly sensitive in ruling out PM-AFL from other left ATAs. When combined with PPI data from the MA, roof area or CTI, PM-, Roof-, CTI-AFL and AT was successfully differentiated with a high predictive accuracy.
A diagnostic algorithm combining CSAT and entrainment pacing is helpful to assess the mechanism of ATAs during catheter ablation of AF.
No preview · Article · Nov 2012 · Circulation Journal
[Show abstract][Hide abstract] ABSTRACT: To date, drug-eluting stent (DES) implantation has not been compared with coronary artery bypass grafting (CABG) for ostial left main coronary artery (LMCA) lesions.
Of the 263 patients in the MAIN-COMPARE registry with ostial LMCA stenosis, 123 were treated with percutaneous coronary intervention (PCI) with DES and 140 with CABG. We compared their 5-year overall survival, composite outcomes of death, Q-wave myocardial infarction (MI) or stroke, and target vessel revascularization (TVR) rates.
Unadjusted analysis showed no significant differences between CABG and DES in overall survival rates (95% confidence interval (CI) for hazard ratio (HR): 0.44 to 1.77, P = 0.71), composite outcomes (death, Q-wave MI, or stroke)-free survival rates (95% CI for HR: 0.41-1.63, P = 0.56), and TVR-free survival rates (95% CI for HR: 0.79-5.03, P = 0.14). Multivariate adjusted Cox regression analysis also showed no significant between-group differences in TVR (95% CI for HR: 0.52-3.79, P = 0.49), death (95% CI for HR: 0.79-2.82, P = 0.22) and the composite of death, Q-wave MI, or stroke (95% CI for HR: 0.65-2.57, P = 0.46). These results were sustained after propensity score adjustment and propensity score matching analysis.
DES implantation for ostial LMCA lesions showed similar 5-year outcomes of death, major adverse events, and TVR compared with CABG. Although meticulous adjustments decreased baseline difference between the two treatments, the absence of statistical significance could be attributable to the size of the study sample and hidden bias.
No preview · Article · Aug 2012 · Catheterization and Cardiovascular Interventions
[Show abstract][Hide abstract] ABSTRACT: Catheter ablation of atrial fibrillation that targets complex fractionated electrogram sites has been widely applied in the management of persistent atrial fibrillation. The clinical outcomes of pulmonary vein isolation alone and pulmonary vein isolation plus the use of complex fractionated electrogram-guided ablation (CFEA) have not been fully compared in patients with paroxysmal atrial fibrillation.This prospective study included 70 patients with symptomatic paroxysmal atrial fibrillation that remained inducible after pulmonary vein isolation. For radio-frequency catheter ablation, patients were nonrandomly assigned to a control group (pulmonary vein isolation alone, Group 1, n=35) or a CFEA group (pulmonary vein isolation plus additional CFEA, Group 2, n=35). The times to first recurrence of atrial tachyarrhythmias were compared between the 2 groups.In Group 2, CFEA rendered atrial fibrillation noninducible in 16 patients (45.7%) and converted inducible atrial fibrillation into inducible atrial flutters in 12 patients (34.3%). Atrial fibrillation remained inducible in 7 patients (20%) after the combined ablation procedures. After a mean follow-up of 23 months, freedom from recurrence of atrial tachyarrhythmias was significantly higher in Group 2 than in Group 1 (P=0.037). In Group 1, all of the recurrent tachyarrhythmias were atrial fibrillation, whereas regular tachycardia was the major mechanism of recurrent arrhythmias in Group 2 (atrial tachycardia or atrial flutter in 5 of 6 patients and atrial fibrillation in 1 patient).We found that CFEA after pulmonary vein isolation significantly reduced recurrent atrial tachyarrhythmia and might modify the pattern of arrhythmia recurrence in patients with paroxysmal atrial fibrillation.
Preview · Article · Jun 2012 · Texas Heart Institute journal / from the Texas Heart Institute of St. Luke's Episcopal Hospital, Texas Children's Hospital
[Show abstract][Hide abstract] ABSTRACT: Carbon nanotubes have emerged as a promising material for multifaceted applications, such as composited nanofiber, field effect transistors, field emitters, gas sensors due to their extraordinary electrical and physical properties. In particular, synthesis of vertically aligned carbon nanotubes with a high aspect ratio has recently attracted attention for many applications. However, mass production of high-quality single-walled carbon nanotubes is still remain elusive. In this study, an effect of chemical vapor deposition conditions, including catalyst thickness, feedstock flow rate, and growth temperature, on synthesis of carbon nanotube was systematically investigated.
[Show abstract][Hide abstract] ABSTRACT: The circadian and seasonal patterns of ventricular tachyarrhythmia (VTA) in patients with early repolarization syndrome (ERS) have not been determined. We compared the timing of VTAs in patients with ERS and Brugada syndrome (BS).
We enrolled patients with ERS (n = 14) and BS (n = 53) who underwent implantable cardioverter defibrillator (ICD) implantation. The timing of VTAs, including cardiac arrest and appropriate shocks, was determined. During follow up of 6.4 ± 3.6 years in the ERS group and 5.0 ± 3.3 years in the BS group, 5 of 14 (36%) ERS and 10 of 53 (19%) BS patients experienced appropriate shocks (P = 0.37). Cardiac arrest showed a trend of nocturnal distribution peaking from midnight to early morning (P = 0.14 in ERS, P = 0.16 in BS). Circadian distribution of appropriate shocks showed a significant nocturnal peak in patients with ERS (P < 0.0001) but a trend toward a nocturnal peak in patients with BS (P = 0.08). There were no seasonal differences in cardiac arrest in patients with ERS and BS. However, patients with ERS showed a seasonal peak in appropriate shocks from spring to summer (P < 0.0001). There was no significant seasonal peak in patients with BS. The timing of VTAs (cardiac arrest plus appropriate shock) showed significant nocturnal distributions in patients with ERS and BS (P < 0.01, respectively). A significant clustering of VTAs was noted from spring to summer (P < 0.01) in patients with ERS, but not in patients with BS (P = 0.42).
Incidence of VTAs showed marked circadian variations with night-time peaks in patients with ERS and BS.
No preview · Article · Feb 2012 · Journal of Cardiovascular Electrophysiology
[Show abstract][Hide abstract] ABSTRACT: Lead-associated endocarditis is a serious complication due to device implantation. The present article reports on a case involving a 57-year-old man with microbiologically and pathologically confirmed lead-associated endocarditis caused by Staphylococcus capitis. Transesophageal echocardiography is essential for diagnosis, and treatment usually requires appropriate antibiotics and removal of the lead.
Preview · Article · Dec 2011 · The Canadian journal of infectious diseases & medical microbiology = Journal canadien des maladies infectieuses et de la microbiologie medicale / AMMI Canada
[Show abstract][Hide abstract] ABSTRACT: We report on the entrapment of an ablation catheter by chordae tendineae in the mitral valve during radiofrequency (RF) ablation of ventricular tachycardia. The entrapped tip had to be removed via open surgery. Great care must be taken when performing radiofrequency ablation around the mitral valve apparatus.
No preview · Article · Nov 2011 · Journal of Cardiovascular Electrophysiology
[Show abstract][Hide abstract] ABSTRACT: In this study, single-walled carbon nanotubes (SWCNTs) were synthesized on a Fe//Si layer by thermal chemical vapor deposition. Metallic SWCNTs were selectively removed by microwave irradiation. Electrical and structural characterizations of the SWCNTs clearly revealed that the metallic SWCNTs were almost removed by microwave irradiation for 120 sec. The remained semiconducting SWCNTs with a high crystalline structure were obtained over 95%. This method would provide useful information for applications to SWCNTs-based field effect transistors and multifaceted nanoelectronics.
[Show abstract][Hide abstract] ABSTRACT: Background
Catheter ablation (CA) is reported to improve left ventricular (LV) function in patients with atrial fibrillation (AF). This study compared the effects of CA and antiarrhythmic drug treatment (AT) on LV remodeling and other echocardiography parameters in AF.
We performed a non-randomized prospective study involving 72 drug-resistant AF patients who were treated with either CA (n = 42) or who declined CA and continued on AT (n = 30). Baseline and follow-up (mean 20.7 ± 7.5 months) echocardiography was performed in all patients. The maintenance of sinus rhythm was determined based on clinical interview, electrocardiography, and 24-h Holter and event recording.
There were no significant differences between the two groups in regard to demographic features, blood pressure, and medication. CA was superior to AT with respect to sinus rhythm maintenance, LV ejection fraction, left atrium (LA) diameter, and LA volume index. In addition, CA resulted in decreases in the LV mass [from 190.5 ± 36.1 to 179.3 ± 32.4 g (p = 0.02)] and the LV mass index [from 104.2 ± 20.5 to 98.2 ± 18.3 g/m2 (p = 0.03)]. No parameter improved in AT patients. These improved echocardiographic parameters were observed in both groups with maintained sinus rhythm.
Reverse LV remodeling after CA may include a reduction in the LV mass index, which appears to be associated with sinus rhythm maintenance.
No preview · Article · Jun 2011 · Journal of Echocardiography