The corrected Q-T interval in the elderly with urban hypothermia.

During winter time in the period from 1993 to 1998, 18 elderly patients: 11 female and 7 male aged 65-88 years, were treated because of hypothermia. Rectal temperature on admission was 20-34.5 degrees C. Ten patients suffered from moderate hypothermia (35-32 degrees C), and eight suffered of severe hypothermia (< 32 degrees C). Arterial hypotension was recorded in 7, and shock in 11 patients. In all of them, and in 18 controls, an electrocardiogram was analyzed with the special reference to the corrected Q-T interval. Decompensated metabolic acidosis was observed in 7/8 patients with severe hypothermia and in 4/10 with moderate hypothermia. Among patients with moderate hypothermia, sinus tachycardia was present in 2, sinus bradycardia in 2, idioventricular rhythm in 2 and atrial fibrillation in 4/10 patients. In patients with severe hypothermia, sinus tachycardia was present in 2, sinus bradycardia in 3, idioventricular rhythm in one, and atrial fibrillation in 2/8 patients. In moderate hypothermia Osborn's or Tomaszewski's J wave was present in 7/10, and it only appeared in 3/10 patients; in severe hypothermia it was present in 6/8 and only appeared in 2/8 patients. The corrected Q-T interval in the group with hypothermia ranged 0.450-0.688 s, in the control group 0.343-0.444 s. The X minimum (s) in the group with hypothermia was 0.508 +/- 0.079, in the control group it was 0.371-0-139 s, and the difference was statistically significant (p < 0.001). The X maximum (s) in the group with hypothermia was 0.576 +/- 0.067 s, in the control group 0.390 +/- 0.019 s, and the difference was also statistically significant (p < 0.0001). In both groups the most significant prolongation of the corrected Q-T interval in the majority of patients was found in anteroseptal leads. The dispersion of the corrected Q-T interval in the group with hypothermia was 87.19 +/- 28.44 ms, in the control group it was 32.06 +/- 8.94 ms, and the difference was statistically significant (p < 0.001).