Carbon monoxide and lethal arrhythmias
- Univ. of Oklahoma Health Sciences Center, Oklahoma City (USA)
The effect of acute exposure to carbon monoxide on ventricular arrhythmias was studied in a previously described chronically maintained animal model of sudden cardiac death. In 60 percent of dogs with a healed anterior myocardial infarction, the combination of mild exercise and acute myocardial ischemia induces ventricular fibrillation. The events in this model are highly reproducible, thus allowing study by internal control analysis. Dogs that develop ventricular fibrillation during the test of exercise and acute myocardial ischemia are considered at high risk for sudden death and are defined as 'susceptible'; dogs that survive the test without a fatal arrhythmia are considered at low risk for sudden death and are defined as 'resistant.' In the current study, the effects of carboxyhemoglobin levels ranging from 5 to 15 percent were tested in resistant and susceptible dogs. A trend toward higher heart rates was observed at all levels of carboxyhemoglobin, although significant differences were observed only with 15 percent carboxyhemoglobin. This trend was observed at rest and during exercise in both resistant and susceptible dogs. In resistant animals, in which acute myocardial ischemia is typically associated with bradycardia even under the control condition, this reflex response occurred earlier and was augmented after exposure to carbon monoxide. This effect may depend on the increased hypoxic challenge caused by carbon monoxide, and thus on an augmentation of the neural reflex activation or a sensitization of the sinus node to acetylcholine induced by hypoxia. In both resistant and susceptible dogs, carbon monoxide exposure induced a worsening of ventricular arrhythmias in a minority of cases. This worsening was not reproducible in subsequent trials. These data indicate that acute exposure to carbon monoxide is seldom arrhythmogenic in dogs that have survived myocardial infarction. (Abstract Truncated)
- OSTI ID:
- 5472535
- Journal Information:
- Research Report Health Effects Institue; (USA), Vol. 36; ISSN 1041-5505
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CARBON MONOXIDE
TOXICITY
HEART
SENSITIVITY
ACUTE EXPOSURE
BLOOD PRESSURE
CARBOXYHEMOGLOBIN
DOGS
EXERCISE
MAXIMUM PERMISSIBLE EXPOSURE
MYOCARDIAL INFARCTION
ANIMALS
BODY
CARBON COMPOUNDS
CARBON OXIDES
CARDIOVASCULAR DISEASES
CARDIOVASCULAR SYSTEM
CHALCOGENIDES
DISEASES
MAMMALS
ORGANS
OXIDES
OXYGEN COMPOUNDS
SAFETY STANDARDS
STANDARDS
VERTEBRATES
560300* - Chemicals Metabolism & Toxicology