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Effects of hyperkalemia on the electrocardiogram of patients receiving digitalis
Insights
Hyperkalemia affects electrocardiograms (ECGs) differently in patients taking digoxin. Digitalis-treated patients showed more frequent atrioventricular junctional rhythms during hyperkalemia.
Area of Science:
- Cardiology
- Clinical Electrophysiology
- Pharmacology
Background:
- Hyperkalemia can significantly alter cardiac electrical activity.
- Digoxin, a cardiac glycoside, affects myocardial contractility and electrical conduction.
- Understanding drug-herb interactions is crucial for patient safety.
Purpose of the Study:
- To investigate the impact of hyperkalemia on electrocardiograms (ECGs) in patients treated with digoxin.
- To compare these ECG effects with those observed in non-digitalis-treated patients experiencing hyperkalemia.
Main Methods:
- Combined prospective and retrospective studies.
- Included patients treated with and without digitalis, with serum potassium (Ks) and ECGs recorded.
- Analyzed serum digoxin concentrations in a subset of patients.
Main Results:
- Hyperkalemia in digitalis-treated patients showed a higher incidence of atrioventricular (AV) junctional rhythm (15/45 vs. 2/76, p < 0.001).
- Longer PR intervals were observed in digitalis-treated patients with Ks > 6.6 mEq/L.
- No patient developed greater than first-degree AV block or required a pacemaker.
Conclusions:
- Hyperkalemia in patients on maintenance digoxin doses can lead to specific ECG changes, notably AV junctional rhythm.
- The presence of digoxin does not appear to exacerbate hyperkalemia-induced conduction delays beyond first-degree AV block.
- Close monitoring of ECGs in digitalis-treated patients with hyperkalemia is warranted.
Abstract:
In a prospective and a retrospective study, the effects of hyperkalemia on the electrocardiogram (ECG) of patients treated with customary maintenance doses of digoxin were examined and the results were compared with the effects of hyperkalemia in patients not receiving digitalis. The prospective study included 11 patients treated and 11 not treated with digitalis, and the retrospective study 27 patients treated and 61 not treated with digitalis. In all patients serum potassium concentrations (Ks) were determined within 1 hour of the recorded electrocardiogram. Serum digoxin concentrations, measured in 11 patients in the prospective and in 4 in the retrospective study, ranged from 0.7 to 5.0 ng/ml, and exceeded 2.0 ng/ml in 10 of 15 patients. Since the results of the prospective and of the retrospective study were similar, they were combined. In patients treated with digitalis, Ks ranged from 5.5 to 6.6 mEq/liter in 21 patients, from 6.7 to 7.5 mEq/liter in 17 and from 7.6 to 8.5 mEq/liter in 6; the Ks was 9.1 mEq/liter in 1 patient. The ventricular rate in patients treated with digitalis ranged from 48 to 140 beats/min, and was not significantly different from that in untreated patients within each range of Ks. Atrioventricular (AV) junctional rhythm occurred more frequently in the electrocardiograms of digitalis-treated patients (15 of 45 vs 2 of 76, p less than 0.001). The average PR intervals were longer in patients treated with digitalis who had Ks greater than 6.6 mEq/liter, but no patient in the study had greater than first-degree AV block, and no patient required a pacemaker.(ABSTRACT TRUNCATED AT 250 WORDS)