The MPVS Ultra system has a useful function that allows users to record either:
- a surface ECG (external ECG) via an ECG cable and appropriate electrodes (electrodes are not available from Millar), OR
- an internal ECG (iECG) signal acquired using a standard PV catheter.
Note that in the case of internal ECG, the catheter acquires the ECG signal while also acquiring the volume data. The input to the internal ECG signal are the electrodes that are also used to produce the primary excitation field. This ensures that the distance between the ECG electrodes is as wide as possible for a maximal signal.
Because the catheter electrodes are placed within a ventricle, the source of the R wave, R waves recorded via iECG are much larger than the other aspects of the ECG signal. While this may not provide all of the detailed waveform information required for an ECG analysis (depending on the study), the iECG signal is ideal for timing calculations (such as heart rate variability etc.).
The ECG output on the MPVS Ultra is a single channel BNC connector located on the front panel. Because there is only one ECG output and one ECG amplifier circuit, it is possible only to record either the internal or external ECG signal at one time. The option as to which ECG signal (if any) is acquired can be selected through the MPVS Ultra control software.