Drug effects on the electrocardiogram. A review of their clinical importance

It is clear that many patients are now being treated with multiple pharmacological agents which may alter membrane function and ionic fluxes across membranes. Therefore, these agents will frequently influence the electrical behavioural of all excitable tissues including the myocardial cell. The changes in the myocardial cell are often reflected by changes, some subtle, some obvious, on the body surface electrocardiogram. Thus, the electrocardiogram provides the physician with a reasonably simple and inexpensive tool for monitoring drug effects and for detecting changes that may be toxic and/or life-threatening. For this reason, an appreciation of these changes by the noncardiologist has become increasingly important.