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Description of the strength-interval relation with external noninvasive pacing
J C Luck1, B P Grubb, M L Markel
1Cardiology Division, University Hospital, Pennsylvania State University, Hershey 17033.
Pacing and Clinical Electrophysiology : PACE
|December 1, 1990
Summary
External pacing (EXP) effectively mimics endocardial pacing for ventricular refractory period assessment. This method provides reliable coupling intervals for programmed ventricular stimulation in most patients.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Devices
Background:
- Assessing ventricular refractory periods is crucial for understanding cardiac arrhythmias.
- Endocardial pacing is a standard method, but external pacing (EXP) offers an alternative.
Purpose of the Study:
- To compare the strength-interval relationship of ventricular refractory periods obtained by external pacing (EXP) versus endocardial pacing.
- To evaluate the efficacy of EXP for programmed ventricular stimulation.
Main Methods:
- Seventeen patients underwent ventricular pacing using both endocardial and external methods.
- Effective and functional ventricular refractory periods (ERP, FRP) were measured at various current thresholds.
- Strength-interval curves were generated for both pacing techniques.
Main Results:
- External pacing (EXP) generated ventricular ERP values significantly longer than endocardial ERP at twice threshold (276 ± 29 ms vs. 235 ± 32 ms).
- EXP ventricular FRP at twice threshold was similar to endocardial ERP but significantly longer than endocardial FRP.
- Strength-interval curves from EXP and endocardial pacing were similar in 82% of patients.
Conclusions:
- External pacing (EXP) can provide critically coupled extrastimuli comparable to endocardial pacing.
- EXP is a viable alternative for programmed ventricular stimulation, offering similar strength-interval relationships in most patients.