Carbon monoxide poisoning causes cardiotoxicity
By Megan Rauscher
NEW YORK (Reuters Health) - Exposure to carbon monoxide gas decreases the heart's ability to contract in a way that is distinct from the effects of oxygen deprivation, and this persists even after all of the carbon monoxide is removed from the system, according to experiments conducted in rats.
"While the exact physiological or biochemical mechanism remains elusive, our results and prior human studies suggest that carbon monoxide has a long-lasting deleterious effect on the cardiac muscle," said lead investigator Dr. Selim Suner of Rhode Island Hospital and Brown University in Providence.
In Academic Emergency Medicine, Suner, and co-author Dr. Gregory Jay, describe the results of their rat heart model, which they used to examine the effects of external perfusion with a saline solution aerated with carbon monoxide on the heart.
They divided 15 rats into three equal groups: a control group (saline and 100 percent oxygen); a nitrogen control group (saline and 70 percent oxygen, 30 percent nitrogen), designed to induce oxygen deprivation; and a carbon monoxide group (saline plus 70 percent oxygen, 30 percent carbon monoxide), designed to simulate carbon monoxide poisoning.
"The design of the study allowed us to eliminate nearly all other variables and look at the effect of carbon monoxide," Suner explained.
Left-ventricular-generated pressure, as an indicator of cardiac function, decreased in the nitrogen and carbon monoxide groups compared with the control group, the researchers report.
The carbon monoxide group did not return to normal cardiac function, including blood pressure, to the extent that the nitrogen control group did upon delivery of 100-percent oxygen during the recovery phase of the experiment.
"While it is difficult and perhaps premature to extrapolate these results obtained in an animal model to clinical practice," Suner said, "our results are consistent with results published earlier in the Journal of the American Medical Association."
These findings indicated that patients with a history of moderate-to-severe carbon monoxide toxicity (requiring treatment in a hyperbaric chamber) had higher rates of illness and death from heart disease years after carbon monoxide exposure.
SOURCE: Academic Emergency Medicine, January 2008.