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[Use of digitalis glycosides in severe disorders of intra-ventricular conduction]
Insights
Digitalis can be safely administered to patients with severe intra-ventricular conduction defects. Studies show no worsening of conduction or increased risk of atrio-ventricular block with digitalis use.
Area of Science:
- Cardiology
- Electrophysiology
Context:
- Severe intra-ventricular conduction defects, such as bilateral bundle branch block and complete right bundle branch block with left antero-superior hemiblock, present challenges for digitalis therapy.
- Previous concerns suggested digitalis might be contraindicated in these conditions due to theoretical risks of worsening conduction defects.
Purpose:
- To evaluate the safety and efficacy of digitalis administration in patients with severe intra-ventricular conduction defects.
- To assess the impact of digitalis on the HV interval in patients with bilateral bundle branch block.
- To determine the incidence of complete atrio-ventricular block in patients with complete right bundle branch block and left antero-superior hemiblock treated with digitalis.
Summary:
- Intracavitary recordings in nine patients with bilateral bundle branch block showed no increase in the HV interval after lanatoside C administration.
- In thirty-four patients with complete right bundle branch block and left antero-superior hemiblock, digitalis treatment resulted in only 5.9% incidence of complete atrio-ventricular block over 16 months.
- The incidence of complete atrio-ventricular block in digitalized patients did not significantly differ from a non-digitalized control group, and therapeutic overdose did not worsen existing blocks.
Impact:
- This study challenges the contraindication of digitalis in severe intra-ventricular conduction defects.
- Findings suggest that digitalis can be safely used in patients with these conduction abnormalities.
- Provides evidence to guide clinical decision-making regarding digitalis therapy in complex cardiac conditions.
Abstract:
The use of digitalis in severe disorders of intra-ventricular conduction is debatable, and some consider it contra-indicated. Once it had been shown that the latter attitude is at best based on contraversial theoretical arguments, two types of study were undertaken: 1. Nine patients with bilateral bundle branch block had intracavitary recordings made of the HV interval both before and for one hour after the administration of lanatoside C (0.8 to 1.6 mg). In no case was this interval found to be increased, indicating that there was no increase in the original conduction defect. 2. Thirty four patients with complete right bundle branch block and associated left antero-superior hemiblock were digitalised, and followed up for an average of 16 months; only 2 complete atrio-ventricular blocks occurred (5.9%). The risk of complete atrio-ventribular block occurring within a year (4.5% in our series) does not differ significantly from that in an identical control group of 38 patients with the same conduction defect, but who were not digitalised (6%). Three patients had a therapeutic overdose of digitalis with no observed increase in their atrio-ventricular block. The authors conclude that it is perfectly in order to digitalise a patient with a severe intra-ventricular conduction defect.