Production of arrhythmias by elevated carboxyhemoglobin in patients with coronary artery disease
Sheps, D. S., Herbst, M. C., Hinderliter, A. L., Adams, K. F., Ekelund, L. G., O'Neil, J. J., Goldstein, G. M., Bromberg, P. A., Dalton, J. L., Ballenger, M. N., Thomas, S. M., & Koch, G. (1990). Production of arrhythmias by elevated carboxyhemoglobin in patients with coronary artery disease. Annals of Internal Medicine, 113(5), 343-351.
OBJECTIVE: To assess the effects of exposure to 4% and 6% carboxyhemoglobin on ventricular arrhythmias in patients with coronary artery disease.
DESIGN: Randomized, double-blind, crossover design.
SETTING: Exercise laboratory with an environmentally controlled exposure.
PATIENTS: Forty-one nonsmokers with documented coronary artery disease.
INTERVENTION: On day 1, a training session with no exposure, the baseline carboxyhemoglobin level was measured, and a supine bicycle exercise test was done. On days 2 to 4, patients were exposed to room air, 100 ppm carbon monoxide (target, 4% carboxyhemoglobin) or 200 ppm carbon monoxide (target, 6% carboxyhemoglobin), and they then did supine bicycle exercise with radionuclide ventriculography. Ambulatory electrocardiogram recordings were made during the 4 consecutive days to determine the frequency of ventricular premature depolarization (VPD) at various intervals.
MEASUREMENTS AND MAIN RESULTS: The frequency of single VPD/h was significantly greater on the 6% carboxyhemoglobin day than on the room air day during the exercise period (167.72 +/- 37.99 for 6% carboxyhemoglobin compared with 127.32 +/- 28.22 for room air, P = 0.03). During exercise, the frequency of multiple VPD/h was greater on the 6% carboxyhemoglobin day compared with room air (9.59 +/- 3.70 on the 6% carboxyhemoglobin compared with 3.18 +/- 1.67 on room air, P = 0.02). Patients who developed increased single VPD during exercise on the 6% carboxyhemoglobin day were significantly older than those who had no increased arrhythmia, whereas patients who developed complex arrhythmias were also older and, in addition, exercised longer and had a higher peak workload during exercise.
CONCLUSION: The number and complexity of ventricular arrhythmias increases significantly during exercise after carbon monoxide exposure producing 6% carboxyhemoglobin compared with room air but not after exposure producing 4% carboxyhemoglobin.