The single precordial lead for ST segment monitoring: comparison with the multiple lead map

A single ECG lead in the serial monitoring of ischemic injury and necrosis in patients with acute anterior myocardial infarction: comparison with 49-lead precordial maps and standard ECGs

To evaluate the single ECG lead with the maximal ST-segment elevation on admission as a modality suitable for monitoring ischemic injury and necrosis, the author correlated the single lead from 49-lead precordial maps and that from the corresponding standard ECGs with the ECG systems from which they derived. A total of 265 pairs of studies (14 per patient) from 20 patients with acute anterior myocardial infarction were used. Serial recordings were done on admission, at 12 predetermined time intervals during hospitalization, and at discharge. The amplitudes of ST-segment elevation, R waves, and Q waves of the single lead and all of the complexes of the corresponding precordial maps or standard ECGs were measured, using the same methodology. The single ECG lead correlated well with the precordial maps and the standard ECG. Although in serial studies the originally selected single lead was not the one displaying the maximal ST-segment elevation in 29% of the studies, it was always located on a locus immediately adjacent to the new lead in the grid recording the maximal ST. Changes in the precordial map or standard ECG were always detected by the corresponding single lead. The single lead from the standard ECG reflected changes in the precordial map, indicating that a precordial map is not necessary on admission for identification of the single lead. Correlations of R waves and Q waves from the single lead and the precordial map or the single lead and the standard ECG were not as good as the ones found for ST-segment elevation, although they provided monitoring of directional changes of the QRS complexes during hospitalization. Thus, a single lead from a precordial map or standard ECG is adequate for monitoring of the magnitude of ischemic injury in patients with acute anterior myocardial infarction. The single lead also provides some information as to the evolution of changes in the precordial QRS complexes associated with infarction and maintains its traditional role of providing surveillance for arrhythmias or conduction abnormalities.

Prospective analysis of electrocardiographic variables as markers for extent and location of acute wall motion abnormalities observed during coronary angioplasty in human subjects

To assess the usefulness of different electrocardiographic variables as markers for the presence, extent and location of new wall motion abnormalities seen after sudden controlled coronary occlusion, 23 patients with isolated left anterior descending (n = 12), or right (n = 11) coronary artery disease and a normal baseline left ventriculogram were prospectively studied during transluminal coronary angioplasty. A simultaneous 12 lead electrocardiogram was recorded before passing the balloon catheter and again at 30 seconds into the fourth inflation cycle. Using a second arterial catheter, a left ventriculogram was obtained at 40 seconds into the fourth inflation cycle. The extent of wall motion abnormalities was described as the percent of left ventricular perimeter showing hypocontractility. During balloon inflation, 19 of the 23 patients developed new hypocontractility ranging from 3 to 40%. ST segment elevation in lead V2 was the most sensitive marker for anterior wall hypocontractility and ST segment elevation in lead III was the most sensitive marker for inferior wall hypocontractility. Highly significant correlations were observed between the extent of the hypocontractile perimeter and 1) the sum of ST segment elevation in all 12 leads; 2) the magnitude of ST segment elevation in either lead V2 or lead III; and 3) the total number of leads with ST elevation greater than or equal to 0.5 mV. No significant changes were seen in the sum of R wave amplitudes, but a significant prolongation of the QT interval was seen during ischemia. In conclusion, acute ST segment elevation parallels the development of new asynergy during transluminal coronary angioplasty.(ABSTRACT TRUNCATED AT 250 WORDS)

Natural course of electrocardiographic components and stages in the first twelve hours of acute myocardial infarction

Time course evolution of R, Q, T and ST components of the electrocardiogram during the first 12 hours of an acute myocardial infarction was studied. A comparison between anterior-extensive and anteroseptal wall infarctions (anterior group), and inferior-extensive and inferior wall infarction (inferior group) showed appearance of significant Q waves within two hours in both groups. R wave loss was nearly a mirror image of Q wave development in both groups. T waves became negative and ST more isoelectric earlier in the inferior than in the anterior group. When combined variations of the four electrocardiographic components were analyzed, four stages of acute infarction were delineated. Stage I--tall R, no Q, ST elevation and positive T; Stage II--significant Q wave appearance; Stage III--negativity of T waves; and Stage IV--ST isoelectric. The inferior group reached stages III-IV within 12 hours; the anterior group remained mostly in stage II. An early appearance of Q waves correlated well with rapid progression to stages III-IV within 12 hours in both infarction groups.