Clinical

By study definition, all patients developed ST elevation in at least one anterior precordial lead during coronary occlusion. No patient developed ST depres­sion in any of the anterior precordial leads; three patients did develop ST depression in lead V5. In­creases in PW were seen in all patients (mean, 14.9 ±8.1 mm Hg; range, 4 to 29 mm Hg). Electro­cardiographic and corresponding hemodynamic data were obtained at approximately 169 ±62 s (range, 75 to 300 s) of coronary occlusion with the total occlusion being 216 ±73 s (range, 110 to 415 s). The inflations were to 6 ± 1 atm.

Elect roca rdiogra phy

Leads V, through V4: Sum of R-wave amplitude in the four precordial leads increased in 17 patients, was unchanged in ten patients, and was decreased in seven patients. Sum of S-wave amplitude decreased in 33 patients (two with complete loss of S wave) and increased in one (Fig 1). Mean R-wave change was 2.7 ± 6.2 mm (range, – 5.5 to 25 mm) and mean S-wave change was —12.9 ±9.0 mm (range, — 38 to 1 mm). The mean precordial ST elevation was 12.5 ±8.7 mm (range, 1.5 to 35 mm). R-wave change correlated directly with ST elevation, (r=.423, p = .013) while S-wave change correlated inversely (Fig 2). R- and S-wave changes were not related (r= — .164, p= .355).
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FIGURE 1. An example of an ECG demonstrating increased R waves (+ 5.5 mm), decreasing S waves (- 8.0 mm), and ST segment elevations (5.5 mm) with coronary occlusion. This case is of special interest as R waves are seen in lead V, with coronary occlusion while they appear absent at baseline.

Lead ST Maximum: The precordial lead with the most prominent ST elevations was Vj in one patient, V2 in 14 patients, V3 in 14 patients, and V4 in five patients. R wave increased in 16 patients, was un­changed in seven patients, and was decreased in 11 patients. S wave decreased in 29 patients (16 with complete loss of S wave), was unchanged in four patients (one with absent S waves on baseline ECG), and increased in one patient. Mean R-wave change was 1.0 ±3.1 mm (range, —3 to 11.5 mm), mean S- wave change was —5.1 ±3.6 mm (range, — 13 to 0.5 mm), and mean ST elevation was 5.4 ± 3.5 mm (range, 1 to 15 mm). The R-wave change correlated signifi­cantly with ST elevation (r=.518, p=.002), but the S-wave change did not (r= — .267, p= .127).

FIGURE 2. The correlation between change in S-wave amplitude and ST segment elevations in leads V, through V4. Changes are in millimeters.

Lead V5: R wave increased in 14 patients, was unchanged in nine patients, and decreased in 11 patients. S wave decreased in 17 patients (11 with complete loss of S wave), was unchanged in 13 patients (ten with absent S waves at baseline), and was in­creased in four patients (two with none at baseline). ST segment was elevated in 23 patients, was un­changed in eight patients, and was depressed in three patients. Mean R-wave change was 0.31 ±1.8 mm (range, —2.5 to 5 mm), mean S-wave change was — 0.91 ±1.6 (range, —6 to 2 mm), and mean ST elevation was 1.0 ±1.5 mm (range, —1 to 5.5 mm) (Fig 3). Changes in R wave did not correlate signifi­cantly with ST deviation (r=.256, p=.145), but changes in S wave had a significant negative correlation (r= .545, p= .001). buy antibiotics canada

FIGURE 3. Changes in R-wave and S-wave amplitudes and ST segment elevations in the entire study population.