Impedance Drop
A decrease in electrical resistance between catheter electrode and tissue during radiofrequency ablation. Indicates effective tissue heating and lesion formation.
Full Definition
Impedance drop refers to the characteristic decrease in electrical resistance observed during radiofrequency catheter ablation when effective heating occurs at the catheter-tissue interface. As tissue temperature increases, cellular proteins denature and tissue impedance decreases, typically by 10-30 ohms from baseline values. This parameter serves as a real-time indicator of effective energy delivery and lesion formation. Inadequate impedance drop may suggest poor catheter contact, insufficient power delivery, or tissue characteristics that resist heating. Conversely, precipitous impedance drops may indicate excessive heating or steam formation. Modern ablation systems monitor impedance continuously and may automatically adjust power delivery based on impedance feedback to optimize lesion creation while minimizing complications.
Usage
Usage note: Critical parameter for assessing effective ablation. Monitored in real-time during procedures.
In Context
- "A 15-ohm impedance drop was observed within 10 seconds of radiofrequency delivery." — ablation report
- "The lack of impedance drop suggested inadequate catheter-tissue contact." — procedural assessment