Production of arrhythmias by elevated carboxyhemoglobin in patients with coronary artery disease

Article Abstract:

Disease of the coronary arteries, the major blood vessels supplying the heart, frequently results in sudden death. Ventricular arrhythmias, or abnormal heart rhythms arising in the ventricles, are a common cause of sudden death, and may be the only symptom of coronary artery disease. Exposure to carbon monoxide, a common environmental pollutant, may cause ventricular arrhythmias and, thereby, contribute to the occurrence of sudden death in patients with coronary artery disease. Exposure to carbon monoxide leads to elevated blood levels of carboxyhemoglobin, the product of the interaction between carbon monoxide and hemoglobin, the oxygen-carrying pigment of the blood. Whether or not carbon monoxide-induced elevations in carboxyhemoglobin cause ventricular arrhythmias was assessed in 41 patients with coronary artery disease. Patients were exposed to room air, and to carbon monoxide levels which produced four and six percent carboxyhemoglobin. They were then required to perform exercise on a bicycle. The heart ventricles were X-rayed during exercise, and the electrical activity of the heart was recorded throughout the procedure to detect the occurrence of ventricular arrhythmias. During the exercise period, the frequency of single or multiple ventricular arrhythmias was greater after the patients were exposed to carbon monoxide producing six percent carboxyhemoglobin. This result did not occur at levels of four percent carboxyhemoglobin. The results also revealed that the patients who developed more frequent ventricular arrhythmias were older. In addition, patients who developed multiple or complex ventricular arrhythmias exercised longer and under greater workloads. These findings demonstrate that, during exercise, the number and complexity of ventricular arrhythmias increase in patients with coronary artery disease who achieve six percent carboxyhemoglobin after carbon monoxide exposure. (Consumer Summary produced by Reliance Medical Information, Inc.)

Physiological aspects, Environmental aspects, Coronary heart disease, Carbon monoxide poisoning, Arrhythmia, Urban health, Carboxyhemoglobin

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Diuretics, beta-blockers, and the risk for sudden cardiac death in hypertensive patients

Article Abstract:

The risk of sudden death may be higher for patients with high blood pressure treated with non-potassium-sparing diuretics. Non-potassium-sparing diuretics are a group of drugs that reduce blood pressure by increasing urine output but do not regulate potassium output. Researchers evaluated diuretics, beta-blocking medications, and health characteristics as sudden death risk factors in 257 patients with high blood pressure who died a sudden death (case-patients). They compared these factors in 257 living patients with similar characteristics who were also taking drugs for high blood pressure (controls). Risk for sudden death was higher in case-patients taking non-potassium-sparing diuretics with or without the addition of beta-blocking medication as compared to case-patients taking potassium-sparing diuretics. Risk for sudden death was lower in case-patients taking both non-potassium-sparing diuretics and beta-blocking medication as compared to case-patients taking only non-potassium-sparing diuretics. More case-patients had a history of heart disease, took more combination medications for high blood pressure, and were more likely to smoke cigarettes than the controls.

Hypertension, Complications and side effects, Drug therapy, Adrenergic beta blockers, Adrenergic beta-antagonists, Diuretics

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A perioperative cardiac risk guideline confirms earlier risk stratification and management recommendations

Article Abstract:

The 1996 practice guideline for perioperative cardiac risk management recommends clinical predictors, functional capacity and surgery-specific risk. Advances in perioperative prophylactic medical therapies with the strongest evidence indicating that Beta-blockers reduce perioperative ischemia and infraction and death in high-risk patients is summarized by the guidelines.

United States, Care and treatment, Practice guidelines (Medicine)

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