DIAGNOSTIC METHODS ELECTROPHYSIOLOGY Detection of local abnormalities in ventricular activation sequence by body surface isochrone mapping in patients with previous myocardial infarction

Body surface isochrone mapping was performed in 36 normal subjects and in 85 patients with previous myocardial infarction. Eighty-seven unipolar electrocardiograms distributed over the anterior chest and the back were recorded simultaneously. For each lead, activation time was measured as the time from the onset of QRS to the peak of the R wave. The lead points where R waves were not observed were designated the "no R wave area" (NR area). Isochrone maps of normal subjects had a consistent pattern, with isochrone lines extending from the right upper anterior chest to the left anterior chest and then to the back. NR area was small and was located only on the right upper chest or the upper back. On the isochrone maps of patients with myocardial infarction, abnormal findings were observed; NR area was found in 26 of 28 patients with anterior infarction on the upper to middle anterior chest, in 13 of 22 patients with inferior infarction on the lower chest, and in 24 of 25 patients with anterior and inferior infarction on the upper to lower anterior chest. Activation time was delayed near the NR area (peri-NR area delay) in 37 patients. In patients with apical infarction, an islandlike zone of delayed activation was typically found on the left precordium. These abnormal patterns are considered to indicate local abnormalities in the activation of infarcted myocardium; the NR area indicates dead unexcitable scar, and the peri-NR area delay and islandlike zone of delayed activation indicate partially infarcted myocardium of slow activation. Patients with NR area had greater degree of left ventricular asynergy and lower ejection fraction than those without. Patients with peri-NR area delay had higher incidence of ventricular arrhythmia than those without. Body surface isochrone mapping provides new evidence of myocardial infarction that is not available by the conventional analysis of the electrocardiogram. Circulation 72, No. 4, 801-809, 1985. BODY SURFACE potential mapping has been used increasingly for the diagnosis of myocardial infarction. 1-7 In the analysis of mapping data, the most conventionally used technique is the instant-by-instant observation of the isopotential maps. Isopotential display has the advantage of presenting simultaneous comparisons of potential at many body surface sites and can demonstrate abnormal potential distribution in patients with myocardial infarction who had no classical diagnostic Q wave in standard 12-lead electrocardiograms (ECGs).3 7 However, detection of subtle disorders in the activation sequence may not always be easy in From the First Department of Internal Medicine, Yamagata University School of Medicine, Yamagata, Japan. Address for correspondence: Kozue Ikeda, M.D., The First Department of Internal Medicine, Yamagata University School of Medicine, Zao-Iida, Yamagata 990-23, Japan. Received Feb. 28, 1985; revision accepted June 20, 1985. Vol. 72, No. 4, October 1985 isopotential mapping because it is very time consuming to analyze many isopotential maps of various times. Comparison of time factors such as local activation time between different leads is difficult in the isopotential map display. Flowers et al. 1, 2 analyzed isopotential maps of anterior and inferoposterior myocardial infarction by departure map technique and found areas of abnormal positivity at the mid and late QRS period. They proposed that the mid and late activation changes detected by the departure map were related to ischemically induced alterations in the temporal sequence of ventricular activation. In this study we attempted to detect the local abnormalities in ventricular activation sequence directly by body surface isochrone mapping. The isochrone map is a display of the distribution of ventricular activation time, and many investigators 801 by gest on A ril 6, 2017 http://ciajournals.org/ D ow nladed from