Related Experiment Videos
Electrophysiological study of atrio-ventricular block and ventricular conduction defects. Prognostic and
Insights
His bundle studies predict advanced atrioventricular block risk. Specific HV intervals and responses during ajmaline testing or atrial pacing identify patients with higher progression rates, regardless of syncope history.
Area of Science:
- Cardiology
- Electrophysiology
- Clinical Medicine
Background:
- His bundle studies are crucial for diagnosing conduction abnormalities.
- Previous research focused on the diagnostic accuracy of ajmaline and overdriving tests.
- The prognostic value of these electrophysiological tests requires further investigation.
Purpose of the Study:
- To evaluate the prognostic significance of His bundle study parameters in predicting advanced atrioventricular block.
- To assess the risk of developing infra-Hisian block based on baseline and provocative test findings.
Main Methods:
- A long-term follow-up (mean 42 months) of 155 patients undergoing His bundle studies.
- Exclusion criteria included sick sinus syndrome, third-degree AV block, active ischemia, and prior cardiac blocks.
- Analysis of baseline HV interval, ajmaline test response (HV interval, AV block), and atrial pacing response (HV interval prolongation, AV block).
Main Results:
- 17 patients (10.9%) developed advanced atrioventricular block during follow-up.
- A baseline HV interval >= 65 ms was associated with a significantly higher risk (33% vs 4.7%, p<0.001).
- Abnormalities during ajmaline testing (HV >= 120 ms or 2nd-3rd degree AV block) or atrial pacing (HV prolongation >10 ms or 2nd-3rd degree AV block) predicted progression (40% vs 0.85-3.4%, p<0.001).
Conclusions:
- His bundle study parameters, particularly baseline HV interval and responses to ajmaline or atrial pacing, are significant predictors of future advanced atrioventricular block.
- These electrophysiological findings hold prognostic value irrespective of a patient's history of syncope.
- Identifying high-risk patients through these tests can guide clinical management and monitoring strategies.
Abstract:
His bundle study with long term follow-up (mean 42 months) was performed in 155 patients (107 with previous syncope, 48 without or with few symptoms). The electrocardiogram showed various conduction abnormalities, but in some cases it was normal. Patients were excluded at the beginning of the study, if they showed sick sinus syndrome, recorded 3rd degree atrioventricular block, angina pectoris, recent myocardial infarction, congenital or surgical cardiac block. In previous studies the diagnostic sensibility and specificity of ajmaline (1 mg/kg/1' i.v.) and overdriving tests have been evaluated. In this study the prognostic meaning of these tests has been evaluated. During a mean 42 months follow-up, 17 patients (10.9%) developed advanced atrioventricular block. A higher risk of developing advanced atrioventricular block below the AV node was detected in patients who showed: basal HV greater than or equal to 65 ms (33% developed advanced atrioventricular block vs 4.7% of patients with basal HV less than 65 ms; p less than 0.001); HV value greater than or equal to 120 ms or 2nd-3rd degree atrioventricular block during ajmaline test (40% progressed to advanced atrio-ventricular block vs 0.85%; p less than 0.001); HV prolonged greater than 10 ms or 2nd-3rd degree atrioventricular block during atrial pacing (40% progressed to a atrioventricular block vs 3.4%; p less than 0.001) regardless of previous syncope.(ABSTRACT TRUNCATED AT 250 WORDS)