Search

Adrenergic beta receptor blocking agents, or beta blockers, are routinely used in the treatment of patients with chronic obstruction of the arteries that supply blood to the heart muscle (coronary arteries). The use of this class of drugs in patients suffering acute bouts of coronary artery blockage (myocardial ischemia) is less well established. Although preliminary results indicate that beta blocker treatment may be beneficial in some cases, the drugs' side effects are poorly characterized, and more studies are required to fully evaluate the effects of beta blockers in acute ischemia. Percutaneous transluminal coronary angioplasty (PTCA), a technique of opening blocked coronary arteries by means of an inflatable balloon at the end of a catheter inserted into the artery, offers a model of temporary coronary artery blockage (which happens when the arterial balloon is inflated). This model was therefore used to evaluate the effects of the ultrashort-acting beta blocker esmolol in 16 patients (11 men and 5 women, ranging in age from 39 to 67 years). Ultrasound and electrocardiographic monitoring of heart function were performed continuously before, during, and after balloon inflation in patients during both drug-free and esmolol-treated conditions. An indicator of myocardial ischemia visible on an electrocardiogram, which is a graphic record of the heart's electrical conduction, is a prolongation and exaggeration of part of the wave known as the ST segment. This was seen in both control and drug-treated condition, but the change was greatly reduced (both in magnitude and duration) by drug treatment. Similarly, the decrease in ejection fraction (the percent of blood ejected from the ventricle during maximal contraction) seen during balloon occlusion was moderated by esmolol treatment, and the abnormalities of cardiac wall motion were delayed. Hence, treatment with esmolol diminishes the extent and delays the onset of myocardial ischemia during acute occlusion of the coronary arteries. (Consumer Summary produced by Reliance Medical Information, Inc.)

The coronary arteries supply blood to the heart, and when they become occluded or narrowed, the diminished blood supply to the heart (myocardial ischemia) can cause pain (angina), heart damage, and sometimes death. In the condition known as unstable angina, myocardial ischemia has progressed to the point where worsening chest pain sometimes signals an impending myocardial infarction (heart attack). A class of drugs known as beta-adrenergic blocking agents, or beta blockers, has been shown to be useful in the treatment of myocardial ischemia. However, in patients with unstable angina, administration of long-lasting beta blockers can sometimes lead to adverse side effects. The development of the ultra short-acting cardioselective beta blocker esmolol has provided a drug that can be administered by continuous intravenous infusion, allowing a minute-by-minute titration of the dose level. To provide data on the use of esmolol in patients with acute myocardial ischemia, 21 patients who had persistent angina despite conventional medical therapy were given this drug. The dose was adjusted on an individual basis to provide a predetermined alteration in cardiovascular function (20 percent decrease in the rate-pressure product). Esmolol administration was effective in alleviating chest pain in 18 of the 21 subjects (86 percent). Seven patients eventually underwent percutaneous transluminal coronary angioplasty (reopening the narrowed segments of the coronary arteries with an inflatable balloon-tipped catheter), eight underwent coronary bypass surgery, and the remainder were discharged and received drug therapy, which included beta blockers. Other than a transient hypotension (excessively low blood pressure), which was corrected with decreased drug dose, there were no significant side effects related to esmolol administration. (Consumer Summary produced by Reliance Medical Information, Inc.)