Search

Ventricular tachyarrhythmia is a potentially fatal outcome of cardiac surgery. Abrupt changes in the hemodynamics after surgical correction of valvular heart disease (VHD) can lead to alterations in ventricular repolarization. We compared the difference between temporal changes in repolarization parameters after correction of left-sided VHD. We retrospectively analyzed the electrograms of patients who underwent surgical correction of isolated VHD between 2006 and 2015 at Asan Medical Center, including mitral stenosis (MS), mitral regurgitation (MR), aortic stenosis (AS), and aortic regurgitation (AR). Ventricular repolarization parameters were measured at pre-specified time intervals after index surgery using a custom-made ECG analysis program. We compared repolarization parameters, including QT and corrected QT intervals, T peak-to-end interval, and corrected T peak-to-end interval. Analysis of 8265 ECGs from 2110 patients (266 MS, 1059 MR, 421 AS, and 364 AR) was performed. Patients with AS were characterized by older age and more comorbidities than other VHDs. The corrected QT interval showed a peak value immediately after surgery and decreased thereafter in the AS groups. However, a gradual increase over 1 month after surgery in AR, MS, and MR groups was observed. The corrected T peak-to-end interval increased in the MS and MR groups and was unchanged in the AS and AR groups. The repolarization parameters of surgery changed dynamically after left-sided valvular surgery. Understanding differential temporal change of repolarization parameters according to the type of VHD would help clinicians avoid fatal arrhythmias related to the repolarization changes. • The QTc intervals generally increased immediately after cardiac surgery. • The repolarization changes evolved in disease- or load-specific patterns. • The corrected QT interval showed a peak value immediately after surgery and decreased thereafter in patients with aortic stenosis. • A gradual increase of QTc interval over 1 month after surgery was observed in other valve disease. [ABSTRACT FROM AUTHOR]

Background: Differentiation of supraventricular tachycardia (SVT) with a right bundle branch block (RBBB) pattern from ventricular tachycardia (VT) is difficult, particularly when the R/S ratio in lead V6 is below 1.0.Objective: We sought to investigate the electrocardiographic criteria for distinguishing between these arrhythmias.Methods: We investigated electrocardiographic parameters from 111 consecutive patients who had RBBB pattern wide QRS complex tachycardia with a reversed R/S ratio in lead V6 (72 VTs, 39 SVTs). Diagnostic criteria from the previous algorithms were compared with our new criterion, the RS/QRS ratio, which was defined as the ratio of the interval from the onset of the QRS complex to the nadir of the S wave, divided by the QRS width in lead V6. The RS/QRS ratio was further tested in a prospective population (31 fascicular VTs, 29 SVTs).Results: The diagnostic accuracy of previous criteria (Brugada algorithm, Vereckei algorithm, and R-wave peak time criterion) was only modest. However, the RS/QRS ratio in lead V6 was significantly lower in SVT than in VT (0.36 ± 0.04 vs 0.50 ± 0.08; P < .001). A cutoff value of the RS/QRS ratio >0.41 differentiated VT from SVT with a high diagnostic accuracy (sensitivity 97.2%; specificity 89.7%). When tested in a prospective population with fascicular VT, the diagnostic accuracy of the criteria was maintained (sensitivity 90.3%; specificity 86.2%).Conclusion: The RS/QRS ratio >0.41 in lead V6 is a simple and reliable index for distinguishing VT from SVT in RBBB pattern wide QRS complex tachycardia with a reversed R/S complex in lead V6. This criterion was particularly useful for the differential diagnosis of fascicular VT from RBBB pattern SVT. [ABSTRACT FROM AUTHOR]

Background: Fasciculoventricular (FV) bypass tracts (BTs) are the rarest form of ventricular preexcitation. Although they are not involved in clinically significant reentrant tachycardia, they may cause diagnostic and therapeutic confusion if not properly understood. This study aimed to assess the impact of FV BTs on the diagnosis and treatment of concomitant arrhythmias and cardiac diseases.Methods: Twenty-two patients with FV BTs who underwent electrophysiologic (EP) study were evaluated. The prevalence of concomitant arrhythmias and cardiac diseases in FV BTs was evaluated. The mechanisms of concomitant arrhythmias were determined by EP study and cardiac diseases were diagnosed by echocardiography.Results: One patient had FV BT with complete infra-Hisian atrioventricular (AV) block that mimicked a slow ventricular escape rhythm. Two patients had FV BT with atrial fibrillation or atrial flutter, which was misinterpreted as AV BT requiring emergency DC cardioversion. Eight patients had accompanying AV BTs. In 2 patients with AV BTs, unnecessary RF application was delivered after successful ablation of AV BT because conduction through a FV BT was mistaken for conduction through a residual AV BT. Five patients had no concomitant arrhythmia; however, two of them had hypertrophic cardiomyopathy with symptoms requiring beta-blocker. Patients had not been prescribed beta-blockers to avoid a proarrhythmic response before the EP study because the FV BTs mimicked AV BTs.Conclusion: FV BTs were frequently accompanied by AV BTs or other arrhythmias and cardiac diseases. They may cause misdiagnosis and inappropriate therapy and even unnecessary RF delivery when misinterpreted as AV BTs. [ABSTRACT FROM AUTHOR]

Objectives The authors aimed to evaluate the role of post-resuscitation electrocardiogram (ECG) in patients showing significant ST-segment changes on the initial ECG and to provide useful diagnostic indicators for physicians to determine in which out-of-hospital cardiac arrest (OHCA) patients brain computed tomography (CT) should be performed before emergency coronary angiography. Background The usefulness of immediate brain CT and ECG for all resuscitated patients with nontraumatic OHCA remains controversial. Methods Between January 2010 and December 2014, 1,088 consecutive adult nontraumatic patients with return of spontaneous circulation who visited the emergency department of 3 tertiary care hospitals were enrolled. After excluding 245 patients with obvious extracardiac causes, 200 patients were finally included. Results The patients were categorized into 2 groups: those with ST-segment changes with spontaneous subarachnoid hemorrhage (SAH) (n = 50) and those with OHCA of suspected cardiac origin group (n = 150). The combination of 4 ECG characteristics including narrow QRS (<120 ms), atrial fibrillation, prolonged QTc interval (≥460 ms), and ≥4 ST-segment depressions had a 66.0% sensitivity, 80.0% specificity, 52.4% positive predictive value, and 87.6% negative predictive value for predicting SAH. The area under the receiver-operating characteristic curves in the post-resuscitation ECG findings was 0.816 for SAH. Conclusions SAH was observed in a substantial number of OHCA survivors (25.0%) with significant ST-segment changes on post-resuscitation ECG. Resuscitated patients with narrow QRS complex and any 2 ECG findings of atrial fibrillation, QTc interval prolongation, or ≥4 ST-segment depressions may help identify patients who need brain CT as the next diagnostic work-up. [ABSTRACT FROM AUTHOR]

Background Predictors of torsades de pointes (TdP) in bradyarrhythmia-induced acquired long QT syndrome are not well defined. Objective The purpose of this study was to search for electrocardiographic (ECG) TdP predictors in patients with acquired atrioventricular block (AVB) and QT prolongation. Methods We analyzed 12-lead ECGs from 20 patients (15 females, age 65.9 ± 15.6 years) with TdP episodes from among 898 AVB patients (2.2%) in 3 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. Results TdP was initiated by premature ventricular complexes with a long–short sequence of activation. The average cycle length of the long sequence was 1289.9 ± 228.9 ms 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 ms vs 523.2 ± 91.3 ms, P = .001), mean T peak to end interval (334.2 ± 59.1 ms vs 144.0 ± 73.7 ms, P = .001) and a higher T peak to end interval/QT ratio (0.49 ± 0.09 vs 0.27 ± 0.11, P = .001) compared with non-TdP controls. TdP patients showed a higher prevalence of notched T waves in which T 2 was at least 3 mm taller than T 1 (45.0% vs 1.3%, P = .001), triphasic T waves (30.0% vs 1.3%, P = .001), reversed asymmetry (20.0% vs 0%, P = .001), and T-wave alternans (35.0% vs 0%, P = .001). An algorithm combining these morphologic 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 for identifying patients with AVB who are at risk for developing TdP. [ABSTRACT FROM AUTHOR]

Background Idiopathic ventricular tachycardia (VT) originating from the outflow tract (OT) usually is considered a benign condition. In rare cases, patients with OT-VT suffer from syncope or even sudden cardiac death. OT-VT is frequently preceded by nonsustained VT (NSVT). Objective The purpose of this study was to clarify if the ECG parameters of NSVTs could differentiate malignant from benign OT-VT. Methods We retrospectively evaluated patients without structural heart disease who had documented OT-NSVT on ECG. ECG parameters were compared between patients with syncope, aborted sudden cardiac death, or ventricular fibrillation (malignant group, n = 36) and patients without syncope (benign group, n = 40). Results There were no differences with regard to age and gender between the malignant and benign groups. On analysis of NSVT, the first coupling interval (CI) of NSVT was comparable between the 2 groups (458 ± 87 ms vs 485 ± 95 ms, P = .212). However, the second CI of NSVT beats was significantly shorter in the malignant group (313 ± 58 ms vs 385 ± 83 ms, P < .0001). During 48-month follow-up, the benign group had a significantly lower recurrence of clinical VT than the malignant group ( P = .046). The malignant group frequently had more than 1 focus of VT, whereas the benign group showed only a single focus (1.82 vs 1.09, P = .023). Conclusion The second CI of NSVT in the malignant group was significantly shorter than that of the benign OT-VT group. Careful measurement of the second CI of NSVT may help identify the malignant form of OT-VT, enabling early treatment to prevent future cardiac events. [ABSTRACT FROM AUTHOR]

Background: L-type calcium channel (LTCC) mutations have been associated with Brugada syndrome (BrS), short QT (SQT) syndrome, and Timothy syndrome (LQT8). Little is known about the extent to which LTCC mutations contribute to the J-wave syndromes associated with sudden cardiac death. Objective: The purpose of this study was to identify mutations in the α1, β2, and α2δ subunits of LTCC (Cav1.2) among 205 probands diagnosed with BrS, idiopathic ventricular fibrillation (IVF), and early repolarization syndrome (ERS). CACNA1C, CACNB2b, and CACNA2D1 genes of 162 probands with BrS and BrS+SQT, 19 with IVF, and 24 with ERS were screened by direct sequencing. Methods/Results: Overall, 23 distinct mutations were identified. A total of 12.3%, 5.2%, and 16% of BrS/BrS+SQT, IVF, and ERS probands displayed mutations in α1, β2, and α2δ subunits of LTCC, respectively. When rare polymorphisms were included, the yield increased to 17.9%, 21%, and 29.1% for BrS/BrS+SQT, IVF, and ERS probands, respectively. Functional expression of two CACNA1C mutations associated with BrS and BrS+SQT led to loss of function in calcium channel current. BrS probands displaying a normal QTc had additional variations known to prolong the QT interval. Conclusion: The study results indicate that mutations in the LTCCs are detected in a high percentage of probands with J-wave syndromes associated with inherited cardiac arrhythmias, suggesting that genetic screening of Cav genes may be a valuable diagnostic tool in identifying individuals at risk. These results are the first to identify CACNA2D1 as a novel BrS susceptibility gene and CACNA1C, CACNB2, and CACNA2D1 as possible novel ERS susceptibility genes. [ABSTRACT FROM AUTHOR]

This study devised an automatic monophasic action potential (MAP) measurement program, and compared the computer-measured MAP durations with those measured manually by two independent observers in order to facilitate the analysis of MAP data obtained during a clinical electrophysiology study. The results were compared at various cycle lengths and during pharmacologic or physiologic interventions. This program identified the onset, plateau, and baseline accurately using the MAP data. The automatically measured MAP durations at the 90% repolarization level (MAPd) strongly correlated with those measured manually (r=0.99). The MAPd shortened in parallel as the pacing cycle length was progressively shortened from 800 to 600, 400 and 300 ms. [Copyright &y& Elsevier]

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. 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 (83.2% 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 2.58; 95% confidential interval = 1.48–4.51, 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 mm3 vs. 44.2 ± 13.6 mm3, p < 0.001, respectively). 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. • The shape of LLR is significantly associated with long-term outcome of AF ablation. • There were more AF recurrences after RF ablation in the patients with narrow LLR. • In vitro study supported that tissue-catheter contact is related to RF lesion size during ablation • MDCT is a feasible and reliable imaging method for assessing the shape of LLR. [ABSTRACT FROM AUTHOR]

Objective Conduction disturbances are common in patients with aortic stenosis. We investigated the incidence, reversibility, and prognosis of conduction disorders requiring permanent pacemaker implantation in patients with degenerative aortic stenosis after isolated aortic valve replacement. Methods This was a retrospective study conducted at a tertiary care center. We evaluated the incidence of conduction disturbances in patients who underwent isolated surgical aortic valve replacement for aortic stenosis between January 2005 and May 2015. Relevant clinical information was obtained from the patients' medical records. Results We reviewed results of 663 patients with pathologically proven degenerative aortic stenosis (bicuspid aortic valve, n = 285 [43.0%]) who underwent isolated aortic valve replacement (mechanical valve, n = 310 [46.8%]). Patients' mean age was 67.1 ± 8.1 years, and 362 were male (54.6%). Immediate postoperative intraventricular conduction disorders occurred in 56 patients (8.4%), and atrioventricular block occurred in 68 patients (10.3%). Ten patients with symptomatic second-degree or third-degree atrioventricular block underwent permanent pacemaker implantation within 30 days of aortic valve replacement. During the mean follow-up period of 1288 ± 1122 days, 64 patients (9.7%) developed irreversible conduction disorders (bundle branch block n = 24 and first-degree atrioventricular block n = 42). Of the 10 patients requiring permanent pacemakers, 4 remained depend on the permanent pacemaker during follow-up. Beyond 30 days after aortic valve replacement, 1 patient underwent permanent pacemaker implantation for de novo conduction disturbance 44 months postoperatively. Conclusions After isolated aortic valve replacement, permanent pacemaker implantation for conduction disturbance is rare (n = 10/663, 1.5%). Isolated aortic valve replacement for degenerative aortic stenosis has a low risk of conduction disturbances during long-term follow-up. [ABSTRACT FROM AUTHOR]

To demonstrate systolic and diastolic asynchrony in patients with left bundle branch block (LBBB), tissue Doppler imaging (TDI) of 4 different walls was performed in 27 normal controls, 29 patients with right ventricular pacing and normal left ventricular (LV) ejection fraction (EF; pacing LBBB), and 35 patients with idiopathic LBBB. Patients with idiopathic LBBB were further classified into those with LVEF >50% and those with LVEF <35%. Asynchrony was calculated as the coefficient of variation of the time intervals from the QRS complex to the peak systolic velocity and to the peak of early diastolic relaxation. Patients with pacing and idiopathic LBBB had significantly longer QRS durations (162 ± 20 vs 92 ± 7 ms, p <0.001) and larger systolic (15.9 ± 5.0% vs 4.1 ± 2.1%, p <0.001) and diastolic (3.7 ± 2.0% vs 1.4 ± 0.6%, p <0.001) asynchrony than controls. Those with idiopathic LBBB and low EF had significantly larger diastolic asynchrony (5.7 ± 2.1%) than those with pacing LBBB (2.9 ± 1.1%) and those with idiopathic LBBB and normal EF (2.0 ± 0.6%). Diastolic asynchrony was the only independent factor that correlated with LVEF (r = -0.64, p <0.001). Thus, idiopathic LBBB with LV dysfunction is characterized not only by systolic but also by diastolic asynchrony. [Copyright &y& Elsevier]