The Millar MPVS Duo can be used with compatible Millar single-segment, tetrapolar catheter models for small animals or compatible Millar Ventri-Cath Variable Segment Length (VSL) catheter models for large animals. Single-Segment catheters have 4 electrodes at a fixed distance, staggering the catheter pressure sensor, as shown in the figure below.
VSL catheters offers four different selections of electrode segments to suit various ventricular sizes. The various segment lengths are user selectable within the Millar MPVS Duo interface. The segment being used will be displayed on the “New PV Loop Protocol: Optimize Catheter Position” screen shown below.
A Ventri-Cath catheter contains seven electrodes, five of which are situated proximal to the pressure sensor and two positioned distally. There are four different selectable segment lengths to accommodate variations in left ventricular volume length. This provides versatility and flexibility when studying hearts of different sizes. The figure below details the different segment selections that span different ventricular scenarios.
If you see an odd shape in your PV loops, the most likely reason is if the volume sensing segment is not placed entirely in the ventricle. During catheter positioning, use LabChart’s XY-View to view the loops from the latest data streaming into LabChart. The goal is to acquire the widest PV loop/stroke volume possible. To achieve this, rotate (clockwise or counter-clockwise), advance, or withdraw the catheter slowly, while monitoring stroke volume/loop width until a stable/optimum loop has been achieved. Additionally, you can monitor the magnitude and phase angle parameters to ensure proper placement. Please see the table below for typical signal ranges.
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