Introduction to LV Conductance Measurements
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This White Paper introduces the concept of the pressure-volume loop as a means to properly assess the performance of the heart as a pump.  A detailed explanation is provided as to how a “conductance catheter” measures blood conductance during the cardiac cycle.  Non-idealities of conductance measurements are introduced to help better understand some of the calibration steps required to obtain an absolute volume measurement. 

Calibration of Conductance Signals for LV Studies
(142 KB)

Conductance Catheters are an invaluable tool which allows beat-by-beat assessment of cardiac function by measuring both ventricular pressure and volume in real-time.  Furthermore, a number of pressure-volume loop derived parameters can be calculated to provide a quantitative assessment of ventricular elastance, ventricular compliance and pump performance.  It is often not necessary to know the absolute volume inside the left ventricle, however, if required, a number of calibration steps must be performed.  This White Paper introduces you to two different methods of calibrating conductance to volume – by solving for Baan’s Volume equation and by using a graduated volume cuvette.   An overview of parallel conductance is also provided and an explanation as to how this value can be determined using the saline dilution method.

Field Uniformity and Electrode Sensitivity
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This document provides an overview of the Scisense “Tunable Segment” Technology specifically used with our larger animal multi-segment conductance catheter system (Scisense GX5).  Historically, different methods have been proposed and applied to try and correct for some of the non-idealities of the conductance catheter, specifically, the non-uniformity of the electrical field.  We provide a technical explanation as to why the tunable segment technology provides a more accurate volume signal to the classical single field and dual-field approach.

Pressure System
Evaluation – Pop Test
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It has been established by researchers that in order to accurately recreate a blood pressure waveform, the sensing system must be able to measure up to the 20th harmonic of the observed waveform.  If not, the resulting signals will be greatly distorted.  An accepted method for evaluating a sensor’s dynamic response is to perform what is commonly known as a pop test.  This paper provides an introduction to the concept of a sensor damping co-efficient and why it is so important to have a sensor that is optimally damped (as it pertains to frequency response and its ability to measure the first 20 harmonics of the observed pressure waveform).

Technical Overview (Admittance)
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The revolutionary ADVantage^TM PV system from Scisense is the only turnkey system to provide absolute LV volumes in rodents without the need for cumbersome and error-prone correction of signals. The ADVantage^TM system offers significant benefits compared to traditional conductance catheter systems:

• no more hypertonic saline bolus injections to calculate parallel conductance
• no more blood cuvette calibrations
• calculation of parallel conductance as a time-varying value
• real-time output of true/absolute LV volume
• catheter position feedback
• save time, money, publish data faster
• use fewer animals

Download a technical overview of admittance volumetry.

Catheter Care & Maintenance
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This document outlines the cleaning and sterilization processes and procedures.

After cleaning and disinfecting procedure is complete, return the Scisense catheter/probe to its original packaging for storage. Store catheter/probe in a cool,
dry place until next use.

Download a copy of the Scisense Pressure and Pressure-Volume Catheter Care and Maintenance Manual