29 October 2008
Smoking, cigarette, Sympathetic stimulation, Linearly corrected, Parabolically corrected, QTc, Repolarization, ventricular, Coronary artery disease, Dinitrophenol, Electrocardiogram, orthogonal, Exercise test, Heart rate, Nicotine, Parasympathetic stimulation, Q-T interval:
30 healthy individuals and 20 patients suffering from coronary artery disease had orthogonal electrocardiograms taken at rest, after moderate exercise and during smoking. The heart rate increased during smoking to approximately the same level as after exercise. The unadjusted Q-T interval did not change significantly during smoking, but it significantly decreased after exercise when its value was compared with that at rest. The linearly corrected Q-T (Q-T/R-R) increased significantly after exercise and even more during smoking. The parabolically corrected Q-T (QTc) increased significantly only during smoking, suggesting that this was not a heart rate dependent phenomenon. The factors responsible for the prolongation of the corrected Q-Ts during smoking could include increased sympathetic tone, slight myocardial ischemia, slight heart decompensation, substances interfering with metabolic processes in the myocardial cell and myocardial strain due to increased cardiac work.