pressure-volume (pv) analyzer

The pv analyzer displays pv loops in real time. The analyzer requires two up to seven inputs (depending on the number of segments on the conductance catheter): pressure signal; total volume signal; and up tofive segment volume signals.

output
Two types of outputs are generated:

1- loop parameters

These are calculated in real time for every single loop. They are as follows:

• maximum and minimum pressure
  
• begin- and end-diastolic pressure
  
• end-systolic pressure
  
• developed pressure
  
• systolic ejection period
  
• diastolic filling period
  
• mean systolic pressure, mean diastolic pressure
  
• contraction time, Relaxation time
  
• min/max dPdt
  
• contractility index
  
• time constant of relaxation (tau) (five Tau parameters are calculated, using five different methods)
  
• average rate of pressure fall
  
• dPdt at P, where P is a user-defined pressure (two parameters calculated, for the rising and falling part of the curve)
  
• minimum and maximum volume
  
• end-diastolic and end-systolic volumes
  
• stroke volume
  
• cardiac output
  
• ejection fraction
  
• stroke work
  
• effective arterial elastance
  
• maximum ventriculer power
  
• preload-adjusted maximal power
  
• potential energy
  
• efficiency
  

2 - series data

Series data are calculated after the acquisition, for series of loopsthat the user selects. The user defines the type of series and then theanalyzer calculates the appropriate data, e.g. (i) time-varyingelastance graphs for occlusion series or (ii) correction volume forsaline dilution series.

end-diastolic pressure-volume relationship (EDPVR) and end-systolicpressure-volume relationship (ESPVR), which are both load-independentindices of LV performance

• time-varying elastance
  
• end-systolic elastance (Ees) also called maximal elastance (Emax)
  
• preload recruitable stroke work (PRSW)
  
• preload adjusted dP/dtmax
  
• dP/dtmax vs end-diastolic volume (EDV)
  

features

• α is entered manually or computed from a reference CO value.
• exclude from analysis individual beats from the series
• print graphs directly to the printer or create JPG images to clipboard
• create a text file, including options for compatibility with PVAN (Millar Instruments’ software for processing pv loops).

setups

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 signalconditioning 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 modulespecifically designed for processing left ventricular PV loop data.