[Problems of Mason-Likar lead system in treadmill exercise electrocardiography].
A Mason-Likar (M-L) leads system has been widely used in the exercise electrocardiography (ECG) using treadmill for the detection of myocardial ischemia. In routine treadmill exercise ECG using M-L lead, we often observe different patterns of ST-T forms those of II, III and aVF on bipolar leads. In this study, on 213 patients, conventional 12 lead ECG and the M-L lead placement ECG were recorded both at supine and standing positions. A careful analysis was made on all the records of patterns, durations, and amplitudes of QRS and T waves. We also evaluated the ST trendgram of patients with no ischemic changes proven exercise TI-201 myocardial single photon emission tomography (SPECT). Quantitative examination showed no significant differences between those in precordial leads of the standard and the M-L lead system in any subjects. The augmented amplitude of QRS and T waves, the disappearance of abnormal Q-waves in II, III, aVF lead, the negative inversion in QRS phase in lead aVL an left axis deviation were often recognized with M-L lead placement. In treadmill exercise ECG, ST depression more than 1 mm in II, III, aVF lead was noted 14 out of 17 patients with no ischemic changes. The all ST-T changes showed "not-decrescendo" type in ST trendgram. We concluded that rigorous evaluation for electrical axis, the configuration of ST-T waves and the existence of myocardial ischemia in leads II, III, aVF was necessary on treadmill exercise ECG using M-L lead replacement.
Murakami
K
K
Department of Central Laboratories, Iwate Medical University, Morioka.
Nakai
K
K
Ito
C
C
Ojima
T
T
Takimura
Y
Y
Toyomaki
S
S
Kobayashi
S
S
Moriai
N
N
Kamata
J
J
Hiramori
K
K
D003327:Coronary Disease / Q000175:diagnosis; D004562:Electrocardiography / Q000379:methods*; D005080:Exercise Test / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011187:Posture