Related Experiment Videos
Atrioventricular block during adenosine thallium imaging
J Lee1, J Heo, J D Ogilby
1Philadelphia Heart Institute, Presbyterian Medical Center of Philadelphia, PA 19104.
Insights
Transient atrioventricular (AV) block during adenosine thallium imaging is common and usually well-tolerated. This temporary block typically occurs early in the infusion and resolves without intervention, even in patients with normal thallium scan results.
Area of Science:
- Cardiology
- Nuclear Cardiology
- Pharmacology
Background:
- Transient atrioventricular (AV) block is a known potential side effect of adenosine administration during myocardial perfusion imaging.
- Understanding the predictors and clinical significance of this transient AV block is crucial for patient safety and accurate interpretation of imaging results.
Purpose of the Study:
- To investigate the predictors and hemodynamic implications of transient second- or third-degree atrioventricular (AV) block during adenosine thallium imaging.
- To compare the characteristics and outcomes of patients experiencing AV block with those who did not.
Main Methods:
- Retrospective analysis of 858 patients undergoing adenosine thallium imaging.
- Comparison of 55 patients with second- or third-degree AV block (group 1) against 803 patients without AV block (group 2).
- Evaluation of baseline characteristics, clinical symptoms, medication use, and thallium imaging results.
Main Results:
- No significant differences in age, sex, baseline heart rate, pre-existing conduction abnormalities, or use of digitalis and beta-blockers between groups.
- AV block occurred within the first two minutes of adenosine infusion in 73% of affected patients and resolved despite continued infusion in 78%.
- Hemodynamic parameters during AV block (heart rate 79±18 bpm, systolic blood pressure 127±27 mm Hg) were generally stable, with premature termination required in only 2%.
Conclusions:
- Transient AV block during adenosine thallium imaging is common, typically occurs early, and is often well-tolerated with no significant hemodynamic compromise.
- The occurrence of AV block is not associated with specific patient demographics, baseline conduction abnormalities, or common cardiac medications like digitalis or beta-blockers.
- Adenosine-induced AV block can occur even in patients with normal myocardial perfusion imaging results and does not necessitate routine aminophylline administration.
Abstract:
Transient atrioventricular (AV) block has been reported during adenosine thallium imaging. This study examined the predictors and hemodynamic implications in 55 patients who had second- or third-degree AV block (group 1) and compared the results with those in 803 patients who did not have AV block (group 2). There were no significant differences in age, sex, or heart rate at baseline between the two groups. ST segment depression was observed in 25% of patients in group 1 and 16% in group 2 (p = NS). Chest pain occurred in 56% in group 1 and 44% in group 2 (p = NS). Preexisting conduction abnormalities (17% vs 16%) and treatment with digitalis (15% vs 15%) and beta-blockers (31% vs 36%) were similar in the two groups. The results of thallium imaging were abnormal in 66% in group 1 and 67% in group 2 (p = NS). Reversible thallium defects were seen in 51% in group 1 and 52% in group 2 (p = NS). The AV block appeared during the first 2 minutes of infusion in 40 patients (73%) and disappeared despite continuation of infusion in 43 (78%). The heart rate during AV block was 79 +/- 18 beats/min, and the systolic blood pressure was 127 +/- 27 mm Hg. Premature termination of adenosine infusion was required in one patient (2%). Aminophylline was used in 5% in group 1 and 2% in group 2 (p = NS). Thus AV block is transient, occurs during the early minutes of infusion, is not aggravated by digitalis or beta-blocker therapy, can be seen in patients with normal perfusion images, and is often well tolerated.