Chapter 20: Cardiovascular Toxicology

INTRODUCTION

Heart disease and stroke cause the majority of deaths in the United States. The major risk factors for coronary heart disease—family history, hypertension, diabetes, lipid abnormalities, and cigarette smoking—explain only a minority of the cases. Other factors, such as stress and exposure to occupational or environmental toxic agents, are believed to contribute to the development of heart disease, although the magnitude of the risk is unknown.

CAUSATION IN TOXIC CARDIOVASCULAR DISEASE

Table 20–1 lists the types and possible toxic causes of cardiovascular disease. Massive exposure may occur (eg, in acute carbon monoxide poisoning), but toxic cardiovascular disease usually is the result of chronic low-level exposures.

Problems in establishing the cause of cardiovascular disease include the following:

• Cardiovascular disease is common even in the absence of toxic exposures.

• There is usually nothing specific, either clinically or pathologically, to point to toxic cardiovascular disease.

• It is rarely possible to document high tissue levels of suspected toxic substances.

• It is difficult to establish occupational exposure levels over the 20 or more years it may take to develop cardiovascular disease.

• Cardiovascular toxic substances are likely to interact with other risk factors in causing or manifesting cardiovascular disease.

With these limitations in mind, this chapter discusses current information concerning toxic cardiovascular disease.

EVALUATION OF PATIENTS

Evaluation of patients with suspected toxic cardiovascular disease should include the following steps:

1. Take a detailed occupational history with attention to the temporal relationship between cardiovascular symptoms and exposure to toxic substances in the workplace.

2. Attempt to document exposure to suspected toxic substances by obtaining industrial hygiene data and, if possible, monitoring worker exposure directly.

3. Evaluate other cardiovascular risk factors.

4. Perform a complete physical examination.

5. Perform appropriate diagnostic studies such as exercise stress testing and coronary angiography to establish the presence and extent of coronary artery disease; echocardiography or radionuclide angiography to establish myocardial disease and the presence of cardiomyopathy; and ambulatory electrocardiographic recordings taken on workdays and at other times to document work-related arrhythmias, paying particular attention to variations in intervals such as PR, QT, and QRS.

CARDIOVASCULAR ABNORMALITIES CAUSED BY CARBON DISULFIDE

Chronic exposure to carbon disulfide appears to accelerate atherosclerosis and/or precipitate acute coronary ...