Digitalis Toxicity

Digitalis toxicity must be considered a serious cardiac emergency when it causes ectopic arrhythmias, conduction defects, and suppression of sinus pacemaking function. It has been estimated that 6% to 20% of patients receiving the glycosides develop digitalis toxicity1,2because of the narrow range that exists between the therapeutic and toxic dose. The therapeutic dose is approximately 60% of the toxic dose.3 There are a number of factors which precipitate digitalis toxicity: (1) overdose, (2) individual idiosyncracy, (3) electrolyte imbalance following potassium loss due to diarrhea or gastric intubation, etc, and (4) calcium administration to the digitalized patient causing a sudden potassium exodus from cardiac muscle.4,5At present, a common precipitating cause of digitalis toxicity is hypokalemia resulting from the use of saluretic drugs in conjunction with digitalis.3,6-9 There is no specific arrhythmia due to digitalis toxicity. When the glycosides are used in excess, or if there is an associated loss