Novel algorithm for identifying T-wave current density alternans using synthesized 187-channel vector-projected body surface mapping.

The noninvasive evaluation of ventricular T-wave alternans (TWA) in patients with lethal ventricular arrhythmias is an important issue. In this study, we propose a novel algorithm to identify T-wave current density alternans (TWCA) using synthesized 187-channel vector-projected body surface mapping (187-ch SAVP-ECG). We recorded 10 min of 187-ch SAVP-ECG using a Mason-Likar lead system in the supine position. A recovery time (RT) dispersion map was obtained by averaging the 187-ch SAVP-ECG. The TWCA value was determined from the relative changes in the averaged current density in the T-wave zone (Tpeak ± 50 ms) for two T-wave types. We registered 20 ECG recordings from normal controls and 11 ECG recordings from nine subjects with long QT syndrome (LQT). We divided LQT syndrome subjects into two groups: group 1 provided 9 ECG recordings without visually apparent TWAs, and group 2 provided 2 ECG recordings with visually apparent TWAs. The QTc interval values in the LQT groups were higher than those in the control (515 ± 60 ms in LQT G-1, 600 ± 27 ms in LQT G-2 vs. 415 ± 19 ms in control, P < 0.001). The RTendc dispersion values among the LQT subjects were higher than those of the control subjects (48 ± 19 ms in LQT G-1, 65 ± 30 ms in LQT G-2 vs. 24 ± 10 ms in control, P < 0.01). The mean TWCA value was significantly higher in the LQT G-2 group with visually apparent TWCAs (0.5 ± 0.2% in control, 2.1 ± 1.2% in LQT G-1, and 32.3 ± 6.9% in LQT G-2). Interestingly, the two-dimensional distribution of TWCA in LQT was inhomogeneous and correlated with the distribution of increased RT dispersion. We conclude that a novel algorithm using 187-ch SAVP-ECG might provide new insights into body surface TWCA.

Interlead difference between T-peak to T-end intervals in resynchronization patients with an implantable cardioverter-defibrillator.

BACKGROUND: The effectiveness of cardiac resynchronization therapy (CRT) in preventing sudden cardiac death is controversial. Epicardial left ventricular pacing reverses the direction of activation of the left ventricular wall from the epicardium to the endocardium. We evaluated whether the interlead difference between T-peak to T-end (Tp-e) intervals determined by a 187-channel repolarization interval-difference mapping electrocardiograph (187-ch RIDM-ECG) is related to the occurrence of ventricular tachyarrhythmia requiring implantable cardioverter-defibrillator (ICD) therapy in heart failure patients receiving CRT with a defibrillator (CRT-D). METHODS AND RESULTS: Repolarization interval-difference mapping electrocardiograph (187-channel) was performed on 61 patients who received CRT-D. Twenty-one patients experienced appropriate ICD therapy. The interlead difference between corrected recovery time intervals was not significantly different between patients with and without appropriate ICD therapy (98 ± 24 milliseconds versus 88 ± 24 milliseconds). The interlead difference between corrected Tp-e intervals was significantly higher in patients with appropriate ICD therapy than in those without (88 ± 22 milliseconds versus 59 ± 23 milliseconds, P < .001). CONCLUSION: The interlead difference between corrected Tp-e intervals determined by 187-ch RIDM-ECG may be related to appropriate ICD therapy in heart failure patients receiving CRT-D.

Image integration of three-dimensional cone-beam computed tomography angiogram into electroanatomical mapping system to guide catheter ablation of atrial fibrillation.

AIMS: To evaluate the feasibility of integrating three-dimensional images created by intra-procedural cone-beam computed tomography (CBCT) into three-dimensional electroanatomical maps (EAM) and compare its accuracy with that of pre-procedural multi-slice CT (MSCT). METHODS AND RESULTS: In 24 patients with drug-refractory atrial fibrillation (AF), atriography using CBCT with pulmonary arterial contrast injection was performed at the beginning of the AF ablation procedure. Intra-procedural CBCT images and pre-procedural MSCT images were individually imported into the EAM system and compared their integration accuracy (point-to-surface distance) of each image and EAM just before ablation. The CBCT images were assessed qualitatively and quantitatively in comparison with MSCT images. All CBCT images were graded as optimal or useful in delineating the left atrium-pulmonary vein anatomy and were successfully integrated with the EAM. Overall, integration accuracy was similar for CBCT and MSCT. However, in 11 patients, the MSCT was performed 5 or more days prior to EAM, resulting in significantly shorter surface-to-point distance in CBCT than that in MSCT (P = 0.047). Radiation exposure with CBCT was significantly reduced compared with MSCT (P < 0.001). CONCLUSION: It is feasible to integrate CBCT image into EAM, and the integration is relatively accurate. Intra-procedural atriography by CBCT may replace pre-procedural MSCT as the imaging source for image integration.

Transverse shifting of the esophagus according to the patient's position helped achieve a safe and successful pulmonary vein isolation procedure.

Although the incidence of causing an atrioesophageal fistula during pulmonary vein isolation is very low, this type of injury results in a very high mortality rate. To prevent this complication, keeping a safe distance from the esophagus to the ablation lesion is a simple but safe method. We report a case in which we were able to shift the position of the esophagus by positioning the patient in a lateral posture in order to keep the esophagus at a safe distance from the pulmonary vein antrum, resulting in performance of a safe and successful pulmonary vein antrum isolation.

Newly developed signal-averaged vector-projected 187-channel electrocardiogram can evaluate the spatial distribution of repolarization heterogeneity.

The purpose of this study was to verify the spatial distribution of myocardial repolarization heterogeneity using a newly developed 187-channel signal-averaged vector-projected ECG (187-ch SAVP-ECG). We constructed corrected recovery time (RTc) and Tpeak-end (corrected Tp-e) dispersion maps using a 187-ch SAVP-ECG based on vector-projection theory using a Mason-Likar lead system. We compared the spatial distribution and quantitative values of dispersion maps by 187-ch SAVP-ECG with those by 64-ch magnetocardiography (MCG) in 27 normal controls (control) and 16 patients (12 myocardial infarction (MI), and 4 dilated cardiomyopathy (DCM)). The wave pattern of the 187-ch SAVP-ECG in the representative cases was similar to those in 64-ch MCG. Spatial distribution increased RTc and corrected Tp-e dispersion maps defined by 187-ch SAVP-ECG were in agreement with those by 64-ch MCG. The value of RTc dispersion in MI was higher than that in control (41 +/- 21 ms in MI versus 30 +/- 12 ms in control, P < 0.05). The value of corrected Tp-e dispersion in DCM was higher than that in control (58 +/- 12 ms in DCM versus 30 +/- 13 ms in control, P < 0.001). There was a good correlation between RTc and corrected Tp-e dispersion values determined by 187-ch SAVP-ECG and 64-ch MCG modalities (y = 0.46x + 18, r = 0.62, P = 0.02 for RTc dispersion; y = 0.52x + 15, r = 0.63, P = 0.01 for corrected Tp-e dispersion). RTc and corrected Tp-e dispersion maps by 187-ch SAVP-ECG based on vector-projection theory can evaluate the spatial distribution of myocardial repolarization heterogeneity.

Chest pain and ST segment depression caused by expansion of gastric tube used for esophageal reconstruction.

We describe a 76-year-old man in whom a gastric tube was used for esophageal reconstruction via the anterior mediastinum after esophagectomy for esophageal cancer. Stenosis of the tube resulted in fluid accumulation, which directly compressed the heart and caused angina-like chest pain associated with ST-segment depression in lead V(2-3) on the electrocardiogram (ECG). Coronary angiography revealed no stenosis. Drainage of the fluid in the gastric tube resulted in immediate relief of symptoms and normalization of ECG. Angina-like chest pain associated with ST segment changes were caused by expansion of the gastric tube and compression of the heart.

The use of a hydrophilic-coated catheter during transradial cardiac catheterization is associated with a low incidence of radial artery spasm.

BACKGROUND: Radial artery spasm (RAS) is a common complication of transradial approach (TRA) to percutaneous coronary angiography (CAG) and coronary intervention. Lower friction resistance between catheter and RA wall may reduce RAS upon insertion, manipulation, and withdrawal of the catheter. The aim of this study was to investigate whether the use of a hydrophilic-coated (HC) catheter, which has lower friction coefficient, could reduce the incidence of RAS compared with a non-hydrophilic-coated (NHC) catheter. METHODS: A total 250 patients attempted diagnostic CAG using 5-French catheters via the TRA between September 2000 and April 2002. Two hundred thirty-four (93.6%) patients who achieved successful coronary cannulation were selected for the study. NHC catheters were used in 149 patients (63.7%), and HC catheters were used in 85 patients (36.3%). We compared the incidence of RAS between NHC and HC catheters. RESULTS: RAS occurred in 17 (7%) patients totally. RAS was less likely to occur in HC group (one patient, 1%) than in the NHC group (16 patients, 11%, P = 0.007). CONCLUSIONS: We conclude that the use of HC catheters can reduce RAS upon insertion, manipulation, and withdrawal of the catheter compared with NHC catheters.