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.
Department of Internal Medicine of Dentistry, Iwate Medical University, 19-1 Uchimaru, Morioka, Iwate, 020-8505, Japan. knakai@iwate-med.ac.jp
Kenji
K
Nakai
Shin
S
Takahashi
Atsushi
A
Suzuki
Nobuhisa
N
Hagiwara
Keisuke
K
Futagawa
Morio
M
Shoda
Tsuyoshi
T
Shiga
Ken
K
Takahashi
Hitoshi
H
Okabayashi
Manabu
M
Itoh
Hiroshi
H
Kasanuki
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D018780:Body Surface Potential Mapping; D016022:Case-Control Studies; D002675:Child, Preschool; D005260:Female; D006352:Heart Ventricles / Q000503:physiopathology*; D006801:Humans; D007564:Japan; D008133:Long QT Syndrome / Q000175:diagnosis* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D056888:Patient Positioning; D011237:Predictive Value of Tests; D012815:Signal Processing, Computer-Assisted; D016683:Supine Position; D013997:Time Factors; D055815:Young Adult