Skip to content

EP 101: Catheter Placement By April Felton

Where are the following catheters located?

What signals are displayed on each channel?

What is the rhythm?


The first three channels displayed are surface ECG leads. A full 12-lead ECG was placed on the patient, but only a few were displayed. Also of note, the sweep speed is approximately 150 mm/sec vs. the standard 25 mm/sec that is seen in electrocardiograms, patient monitoring areas, and in cathlab procedures. This is due to the complexity of the intracardiac signals. The sweep speed is “spread out” to observe the subtle difference in waveforms and activation patterns.

Next is the first displayed intracardiac channel.  The HRA catheter placed near the SA node, recording only atrial activation.

The three yellow channels are from the His catheter. This catheter is positioned just past the tricuspid valve, partially in the atrium and ventricle; therefore, displaying an A and V signals. The His signal is the sharp signal in-between when the impulse zips down the His-Purkinje system.

All standard (not high-density) catheters begin the numbering system at the distal tip. So, in this example the CS 1,2 is on the far-left side of the heart and CS 9,10 is at the CS ostium.

Lastly is the RV channel. This catheter in the current position will only display ventricular activation.

This patient is in sinus rhythm as seen by the high-to-low and right-to-left activation pattern.

Picture 2