Using an inferior vena cava anode for unipolar His-bundle electrograms yields a better signal-to-noise ratio than a chest skin patch, while a 50-500 Hz filter decreases His bundle amplitude (0.32 vs 0.38 mV; P<0.01).
Does anode location and filter setting affect the amplitude, duration, morphology, and signal-to-noise ratio of unipolar His-bundle electrograms in patients undergoing EP studies?
Using an electrode catheter in the inferior vena cava as the anode provides the optimal signal-to-noise ratio for recording unipolar His-bundle electrograms.
Absolute Event Rate: 0.32% vs 0.38%
p-value: p=<0.01
Although "unipolar electrograms" recorded from the His-bundle position have been used to help position catheters for His-bundle ablation, the techniques used to record such electrograms have not been standardized. The effects of five anode locations (right chest wall, anterior chest wall, left chest wall, posterior chest wall, and inferior vena cava) on unipolar atrial, His bundle and ventricular electrograms recorded from the His-bundle position were examined in ten patients undergoing clinical electrophysiology studies. Electrograms were recorded at filter settings of 50-500 as well as 0.05-1000 Hz. The location of the anode had no consistent effect on the amplitude, duration or morphology of any of the electrograms at either filter setting, but signals recorded with the inferior vena cava anode had the highest signal-to-noise ratio. A filter setting of 50-500 Hz decreased the amplitude of atrial (0.72 to 0.33 mV-P less than 0.01), His bundle (0.38 vs 0.32 mV-P less than 0.01) and ventricular electrograms (3.71 vs 2.01 mV-P less than 0.001) compared to a filter setting of 0.05-1,000 Hz. The filter setting did not affect electrogram duration. We concluded that the use of an electrode catheter in the inferior vena cava as the anode when recording "unipolar electrograms" from the His-bundle position yields a better signal-to-noise ratio than a skin patch on the chest and appears to be the optimal method for recording unipolar electrograms.
Kadish et al. (Fri,) conducted a other in Undergoing clinical electrophysiology studies (n=10). Inferior vena cava anode and 50-500 Hz filter setting vs. Chest wall anode and 0.05-1000 Hz filter setting was evaluated on His bundle electrogram amplitude (mV) (p=<0.01). Using an inferior vena cava anode for unipolar His-bundle electrograms yields a better signal-to-noise ratio than a chest skin patch, while a 50-500 Hz filter decreases His bundle amplitude (0.32 vs 0.38 mV; P<0.01).