Propafenone for Cardiac Arrhythmias

Abstract

This chapter discusses several positive inotropic drugs and drugs used in dysrhythmias. Plasma potassium concentrations normally rise during exercise. In the study discussed in the chapter, in nine patients with atrial fibrillation during exercise at 75 W in the absence of digoxin, the peak serum potassium concentration was 4.6 mmol/L; when the serum digoxin concentration was 1.1 nmol/L, it was 4.8 mmol/L, and when the serum digoxin concentration was 2.5 nmol/L, it was 5 mmol/L. This greater increase in plasma potassium concentration during exercise in patients taking digoxin might increase its dysrhythmogenic effects. The most common presentation of digitalis toxicity in therapeutic use is with gastrointestinal adverse effects, commonly anorexia, nausea, vomiting, and diarrhea. This is also the case when poisoning occurs because of traditional medicines containing cardiac glycosides. The adverse effects of antidigoxin antibody fragments are discussed in the context of the management of digitalis toxicity. The frequency of adverse events was low (7%) and included allergic responses, possible recurrence of digitalis toxicity after treatment, and some effects attributable to the withdrawal of digitalis, such as worsening of heart failure. Amrinone can cause vasodilatation and hypotension after intravenous administration. This was reported in patients who were given intravenous amrinone rapidly during cardiopulmonary bypass. In the study discussed in the chapter, amrinone reportedly further increased intracranial pressure in a 13-year-old girl with pre-existing cerebral damage.