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Electrophysiologic changes after tiapamil in coronary and noncoronary patients
Insights
Tiapamil administration prolonged the P-R interval, indicating a delay in atrioventricular conduction. These effects were more pronounced in patients with coronary artery disease and at higher doses.
Area of Science:
- Cardiology
- Pharmacology
- Electrophysiology
Background:
- Right heart catheterization is a diagnostic procedure.
- Coronary artery disease (CAD) affects cardiac function.
- Atrioventricular (AV) conduction is crucial for heart rhythm.
Purpose of the Study:
- To investigate the electrophysiological effects of tiapamil.
- To assess the impact of tiapamil on AV conduction and hemodynamics.
- To explore dose-dependent effects and influence of CAD.
Main Methods:
- 26 patients underwent right heart catheterization.
- His bundle recordings and atrial pacing were performed.
- Measurements included P-R interval, A-H time, heart rate, and blood pressure before and after tiapamil administration (1 or 1.5 mg/kg IV).
- Selective coronary angiography was used to identify CAD.
Main Results:
- Tiapamil significantly increased the P-R interval (153 to 168 ms) and A-H time (88 to 97 ms).
- Arterial blood pressure and heart rate decreased significantly post-administration.
- Effects were more pronounced in patients with coronary artery disease.
- Higher tiapamil dosage (1.5 mg/kg) resulted in greater changes compared to 1.0 mg/kg.
- Sinus node recovery time showed a non-significant trend toward increase.
Conclusions:
- Tiapamil demonstrably slows atrioventricular conduction.
- Hemodynamic effects include decreased heart rate and blood pressure.
- Coronary artery disease may potentiate the electrophysiological effects of tiapamil.
- Dose-response relationship observed, with higher doses yielding more significant effects.
Abstract:
26 patients who had undergone right heart catheterization were enrolled in the study. The average age was 51.7 +/- 15 years. Half the patients showed coronary artery disease at selective coronary angiography. His bundle recordings and atrial pacing were performed before and 10 min after 1 or 1.5 mg/kg i.v. tiapamil. In addition, arterial blood pressure was recorded. P-R interval increased from a mean value of 153 +/- 36 to 168 +/- 49 ms (p less than 0.05) due to an increase in the A-H time from 88 +/- 19 to 97 +/- 23 ms (p less than 0.05). Arterial blood pressure and heart rate decreased significantly. These changes were more pronounced in patients with coronary artery disease. In the groups with the higher dosage, the differences from the control values were greater than in the patient groups receiving 1.0 mg/kg. Sinus node recovery time tended to increase in all groups but the differences did not reach significance. Patients with the 'sick sinus syndrome' were not studied.