Production of arrhythmias by elevated carboxyhemoglobin in patients with coronary artery disease.
OBJECTIVE
To assess the effects of exposure to 4% and 6% carboxyhemoglobin on ventricular arrhythmias in patients with coronary artery disease.


METHODS
Randomized, double-blind, crossover design.


METHODS
Exercise laboratory with an environmentally controlled exposure.


METHODS
Forty-one nonsmokers with documented coronary artery disease.


METHODS
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.


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.


CONCLUSIONS
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.
Sheps
D S
DS
University of North Carolina, Chapel Hill.
Herbst
M C
MC
Hinderliter
A L
AL
Adams
K F
KF
Ekelund
L G
LG
O'Neil
J J
JJ
Goldstein
G M
GM
Bromberg
P A
PA
Dalton
J L
JL
Ballenger
M N
MN
D000367:Age Factors; D000368:Aged; D000393:Air Pollutants / Q000009:adverse effects*; D001145:Arrhythmias, Cardiac / Q000097:blood / Q000000981:diagnostic imaging / Q000209:etiology*; D002248:Carbon Monoxide / Q000009:adverse effects*; D002263:Carboxyhemoglobin / Q000378:metabolism*; D002985:Clinical Protocols; D003327:Coronary Disease / Q000097:blood* / Q000150:complications / Q000000981:diagnostic imaging; D004311:Double-Blind Method; D005080:Exercise Test / Q000187:drug effects; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D015635:Radionuclide Ventriculography; D011897:Random Allocation; D013997:Time Factors
D000393:Air Pollutants; D002248:Carbon Monoxide; D002263:Carboxyhemoglobin