hardware and software solutions for pressure-volume loop studies in small rodents to large animals

emka TECHNOLOGIES provides complete hardware and software solutions for pressure-volume (pv) loop studies in a wide range of species, from small rodents to large animals.

The systems use the conductance catheter technique for the volume signal. The catheter has several ring electrodes along its length and is positioned in the left ventricle. Conductance between pairs of electrodes is measured. iox2 software uses these measurements to calculate up to 5 segmental volumes, and in turn total left ventricular volume.

Pressure changes within the left ventricle are measured and combined with the volume data in real time to create PV loops.

emka TECHNOLOGIES provides full setups for left ventricular PV loop studies for all species.

Several models of catheters are made by Millar Inc, including the Ultra-Miniature Pressure-Volume Catheters for rodents.

The pressure and volume signals travel from the catheter, to the signal conditioning unit (model MPVS-300 from Millar) then to a strain-gauge amplifier board in the amplifier mainframe.

The outputs from the amplifier mainframe go to the acquisition card of the PC via the interface box.

The PC must be running iox2 for the acquisition. The pressure-volume analyzer is an add-on module specifically designed for processing left ventricular PV loop data.

The dedicated PV loops analyzer (iox2 data acquisition software) performs complete analysis on loops during steady-state and changing conditions (e.g. vena cava occlusion or saline bolus injection for calculating parallel conductance correction factor)

features

The practical and powerful software allows you to:

• generate, enter or re-use existing parallel conductance correction
• generate or enter alpha correction factor
• select pv loops for analysis
• fit curves using linear or nonlinear regression
• invalidate specific beats in a series (to increase the accuracy of the regression)
• display several series on the same graph (to compare different occlusions)
• display loops from single or multiple subjects simultaneously
• review and export results to Excel
• do all this in full compliance with 21 cfr part 11 & glp requirements

parameters

The PV loops analyzer generates several parameters including:

• End-Systolic Pressure-Volume Relationship (ESPVR)
• End-Diastolic Pressure-Volume Relationship (EDPVR)
• preload recruitable stroke work relationship (PRSW)
• arterial elastance (Ea)
• stroke work

Real-time volume signals may also be obtained using sonomicrometry.

Another way of assessing cardiac contractility is to analyze pressure-distance loops, in which the distance is typically myocardial segment length or wall thickness measured by sonomicrometry transducers. A dedicated iox analyzer is available for this purpose.