[Digitalis intoxication: specifity and significance of cardiac and extracardiac symptoms. part I: Patients with digitalis-induced arrhythmias (author's transl)].

In 1164 cases clinical and electrocardiographical findings were correlated with serum digoxin concentrations (SDC). The diagnosis of digitalis intoxication was based on rhythm disturbances which disappeared on withdrawel of the drug. The mean SDC for patients with digitalis-induced arrhythmias was 3.07 ng/ml compared to 1.02 ng/ml for patients with normal Ecg's and 1.01 ng/ml for patients with rhythm disturbances of other origin. Taking 2.0 ng/ml as the lower limit of digitalis intoxication a more than 85% coincidence was found between the diagnosis based on serial Ecg's and on SDC levels. No signs of cardiac toxicity were found in patients with SDC's less than 1.6 ng/ml, some patients, however, showed normal Ecg's despite SDC's up to 4.5 ng/ml. Patients with SDC's greater than 1.9 ng/ml and normal Ecg's were significantly younger than patients with digitalis-induced arrhythmias at comparable SDC's. Although no definite diagnosis of cardiac toxicity could be established in 327 cases, the clinical data of patients with SDC's of 2.0 ng/ml and greater resemble closely those with digitalis-induced arrhythmias while patients with SDC's less than 2.0 ng/ml showed close resemblance to patients with no cardiac evidence of toxicity with regard to: mean age, kidney function, mean digoxin dosage and mean body weight. Patients with elevated SDC's showed a 45% incidence of severely impaired kidney function in contrast to 28% of the patients with SDC's less than 2.0 ng/ml. Even in patients with normal kidney function the correlation between the orally administered digoxin dosage and SDC levels was poor. The correlation was significantly better when dogoxin was administered intravenously. Therefore knowing the amount of digoxin taken (according to the patient's statement) seems of little benefit in the evaluation of digitalis toxicity. In patients with digitalis-induced arrhythmias mean age and mean body weight were significantly lower, mean creatinine concentration and the incidence of severe cardiac insufficency and of typical ST-T-changes were significantly higher. There was no significant difference in mean potassium concentration and incidence of coronary artery disease compared to nontoxic patients. Compared to patients with cardiac arrhythmias of other origin there were no significant differences in mean age, mean potassium and creatinine concentrations and cardiac insufficiency while the incidence of coronary artery disease was significantly higher among patients with rhythm disturbances of other origin. Every type of rhythm disturbance can be digitalis-induced. Among our patients the incidence of digitalis-induced second-degree atrioventricular block (Wenckebach), ventricular bigeminy, nonparoxysmal nodal tachycardia and PAT with block was significantly higher while patients with rhythm disturbances of other origin showed an equally high incidence of PVB's and prolongation of PQ interval...