We have completed a prospective, multi-center, non-randomized 20 patient pilot trial to determine the accuracy and reliability of CardioVol™ in measuring ventricular volumes using an RV shocking lead. The trial was conducted in patients during a routine CRT-D or ICD generator replacement procedure.
The trial steps were as follows.
- Remove the old generator and disconnect leads
- Connect RV leads to CardioVol and RA leads to an external pacemaker
- Make simultaneous CardioVol and 3D trans-thoracic echo measurements during rapid atrial pacing (to reduce SV) and dobutamine infusion (to increase SV)
- Disconnect CardioVol from the leads and continue with generator replacement
Clinical Results and Analysis
CardioVol follows expected physiological trends
- Rapid atrial pacing in the heart is known to decrease both the EDV and SV due to decreased filling times. CardioVol detected a drop in EDV and SV, as indicated in the graphs below.
- Dobutamine is a positive ionotrope and causes an increase in cardiac output by increasing SV. CardioVol detected an increase in SV during dobutamine infusion when compared to both baseline and rapid pacing, as shown in the graph below.
CardioVol exhibits high repeatibility and reliability
- Repeatability can be quantified using the Within-Subject Coefficient of Variation (wCV), which is defined as the standard deviation divided by the mean.
- wCV is commonly referred to as the “error rate”, with 0% indicating perfect repeatability and 10% or higher indicating poor repeatability.
- CardioVol is much more repeatable than 3D echo, as shown by the graph below.
Agreement Statistics of CardioVol with 3D Echo
- CardioVol exhibits good agreement with 3D echo for volume measurements in the ventricle.