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Factors affecting transthoracic impedance during electrical cardioversion
S J Sirna1, D W Ferguson, F Charbonnier
1Department of Internal Medicine, University of Iowa Hospitals, Iowa City 52242.
The American Journal of Cardiology
|November 15, 1988
Summary
Transthoracic impedance (TTI) decreases after cardioversion, with factors like energy delivered and breathing influencing it. Proper coupling agents are crucial for accurate TTI measurements during cardioversion.
Area of Science:
- Cardiology
- Biomedical Engineering
Background:
- Successful cardioversion relies on adequate electrical current delivery.
- Current is a product of delivered energy and transthoracic impedance (TTI).
Purpose of the Study:
- To investigate factors influencing transthoracic impedance (TTI) in humans undergoing cardioversion.
- To understand the impact of electrical shocks and measurement conditions on TTI.
Main Methods:
- Monitored TTI in 28 patients undergoing elective cardioversion.
- Studied 10 healthy subjects for comparison, testing different coupling agents and breathing phases.
- Assessed TTI changes up to 48 hours post-shock and correlated energy delivery with TTI decline.
Main Results:
- TTI decreased post-cardioversion and remained lower than baseline for at least 24 hours.
- Total energy delivered correlated with TTI reduction (r=0.69).
- TTI varied with respiration (lower at end-expiration) and was significantly affected by coupling agent type and presence.
Conclusions:
- Electrical shocks reduce TTI, an effect that persists post-procedure.
- Respiration and coupling agent selection significantly impact TTI measurements.
- Understanding these factors is vital for optimizing current delivery during cardioversion.