Ventricular Pressure-Volume

Overview:

Changes in ventricular function can be visualized through the use of ventricular pressure-volume (PV) loops, typically recorded using a single pressure-volume (or conductance) catheter inserted directly into the left ventricle. To generate a PV loop for the left ventricle, instantaneous left ventricular pressure (y-axis) is plotted against left ventricular volume (x-axis) during a complete cardiac cycle.

An example left ventricular PV loop is shown below:

Hemodynamic parameters such as stroke volume, cardiac output, ejection fraction, stroke work, end-systolic pressure-volume relationship (ESPVR), end-diastolic pressure-volume relationship (EDPVR), and many other industry-standard parameters can be derived from PV loops. Typical PV analysis applications include:

  • Baseline PV studies
  • Occlusion PV studies
  • Phenotyping gene manipulations
  • Cardiac hypertrophy
  • Cardiac failure
  • Cardiovascular remodeling
  • Toxicology
  • Pharmacology (rapid drug screening)
  • Cardiac resynchronization therapy
  • Surgical interventions

 

 

Method:

Ventricular Pressure-Volume

ADInstruments and Millar Instruments provide researchers with the world's first system for simultaneous pressure-volume recordings in small to large animals using a single catheter. The systems are specifically designed for beat-to-beat monitoring of cardiac performance in animals ranging in size from mice to sheep. A single catheter with a high-fidelity pressure sensor and conductance electrodes is used to simultaneously measure left ventricular pressure and volume. PV catheters connect to PowerLab data acquisition systems via the MPVS Ultra Pressure-Volume Unit.

Surgical Techniques

Pressure-volume catheters may be inserted into the left ventricle by either a closed chest carotid artery catheter insertion or an open chest apical stab catheter insertion (protocols by Pacher et al, 2008, Nat Protoc. 2008; 3(9): 1422–1434).

Impedence/Conductance Technique

The impedance/conductance technique is based on Ohm’s Law (V=I·R ) where V is equal to the voltage potential between the sensing electrodes, I is equal to a low excitation constant current, and R is the resistance of the left ventricular blood pool. Since conductance is equal to the inverse of resistance, we can derive the following relationship between volume and conductance:

Vp = I·R

C =1/R, ∴ R=1/C
Vp =1/C, ∴ C =1/Vp

C = Volume = 1/Vp

 
The volume of the left ventricular blood pool is high during diastole. Therefore, resistance of the blood pool is low and conductance of the blood pool is high. The voltage drop across the sensing electrodes is low during diastole. During systole the volume of the left ventricular blood pool is low. Therefore, resistance is high and conductance of the blood pool is low. The voltage drop across the sensing electrodes is high during systole.

Pressure Calibration

A Pressure Gauge can be used to calibrate both conventional fluid-filled pressure transducers and Millar Mikro-Tip pressure catheters into units of mmHg. For information on Pressure Transducer Calibration, refer to the Pressure Transducer Calibration (64 KB) technique note.

Volume Calibration

Volume calibration is used to convert the data generated by the conductance (pressure-volume) catheter from units of conductance (RVU, μmho, μS) or resistance (ohms) to units of volume (μL). There are three methods for volume sensor calibration:

  • RVU Calibration (relative volume units) can be used when researchers are only interested in relative ventricular volume changes.
  • Cuvette Calibration can be used if absolute volumes are required. An actual blood sample from the animal is used and added to an insulated calibration cuvette with different size wells.
  • Saline Calibration should be used if correction for parallel conductance or parallel volume (Vp) is required. Saline is injected into the heart while it is still beating in order to calculate Vp.

Recording Settings

For information on recommended pressure-volume sampling rates and filtering options, refer to the Signal Filtering (199 KB) technique note.

Related Areas of Interest:

Software:

The LabChart Advantage:

(may require additional Modules and Extensions)

  • The Units Conversion feature can be used to convert signals into relevant units e.g. mmHg, RVU, μl
  • Using LabChart features such as Cyclic Measurements, Arithmetic and Data Pad, ventricular parameters such as maximum, minimum and mean pressure can be easily recorded and displayed in real-time.
  • Macros can automate many tedious and repetitive analysis tasks.
  • The XY View feature can be used to generate PV loops.
  • The PV Loop Module enables graphical display of the pressure-volume relationship and extraction of hemodynamic parameters including pressure volume area, stroke work, and cardiac output.
  • The Blood Pressure Module enables beat-by-beat or signal-averaged analyses of arterial and ventricular waveforms.
  • Extracted parameters in the Data Pad, BP or Hemodynamics Table View can be easily exported for further analysis, e.g. in Excel or Matlab.

LabChart

LabChart software (for Windows and Macintosh) together with a PowerLab data acquisition system offers up to 32 channels of real-time data acquisition, data integrity, easy selection of hardware settings, powerful online and offline analysis, procedure automation, seamless extraction of experimental data and flexible display options. Additional acquisition and analysis functionality is provided with the use of specialized LabChart Extensions and LabChart Modules. Modules are available as part of LabChart Pro while Extensions are free for download from the website for existing LabChart users.

PV Loop Module

The PV Loop Module (Windows) records and analyzes left ventricular pressure and volume data for hemodynamic research in animals. Analyses can be conducted in real-time or offline.
 

It features:

  • Loop View- plots and displays the key cardiac parameters and allows individual loops to be reviewed and selected for inclusion/exclusion in analyses. Parameters include;
    • ESPVR (End Systolic Pressure-Volume Relationship). The slope of the ESPVR curve is an index of myocardial contractility; the steeper the ESPVR curve, the greater the cardiac contractility.
    • EDPVR (End Diastolic Pressure-Volume Relationship). The slope of the EDPVR curve is an indicator of ventricular compliance; the steeper the curve, the greater the ventricular stiffness.
  • Haemodynamics Table- reports parameters for each individual loop including:
    • Stroke Work
    • Cardiac Output
    • Ejection Fraction
    • Tau (the Isovolumic Relaxation Constant)
  • Analysis Plots
    • PRSW Plot: Displays Preload-Recruitable Stroke Work which is used as an index of contractility
    • dP/dt Max vs. EDV Plot: Shows the steepest slope during the upstroke of the pressure curve versus the end diastolic volume and is used as an index of contractility
    • PVA vs. EDV Plot: Shows pressure volume area versus the end diastolic volume which represents the mechanical energy generated by contraction of the ventricle
    • PVA vs. ESP Plot: Shows pressure volume area versus the end systolic pressure which represents the mechanical energy generated by contraction of the ventricle
    • Note: What the PVA vs. EDV, and PVA vs. ESP plots provide is a way of fitting a straight line to the data and obtaining an estimate of the slope parameter. This slope parameter can then be used a measure of contractility.
  • Automated Calibration
    • Cuvette calibration - for calculating absolute volume units using calibration cuvettes
    • Saline calibration - for determining parallel conductance of the ventricular wall (Vp)


Blood Pressure Module
The Blood Pressure Module (Windows) automatically detects, analyzes and reports cardiovascular parameters from arterial or ventricular pressure signals.

It provides:

  • Real-time analysis and data extraction of pressure parameters
    • Max and min pressures
    • Max and min dP/dt
  • Analysis of blood and cardiac pressure in real-time or offline
  • Automated detection of pressure cycles
  • Automated tabulation and data extraction of pressure parameters
  • Analysis View
    • Averaging of pressure waveforms
    • Automated pressure parameter labelling

Calculated ventricular parameters include:

  • Maximum Pressure
  • Maximum dP/dt
  • Isovolumic Relaxation
  • Minimum Pressure
  • Minimum dP/dt
  • Mean Pressure
  • End Diastolic Pressure (EDP)
  • Maximum-Minimum Pressure
  • Contractility Index


GLP and 21 CFR Part 11
For those researchers working within a laboratory requiring GLP and 21 CFR Part 11 compliance, the GLP Client and GLP Server are available for use with LabChart (Windows only) and PowerLab data acquisition systems. For more information, visit the Good Laboratory Practice application page or contact your nearest ADInstruments representative.

Hardware:

PowerLab Data Acquisition Systems

The PowerLab is a high-performance data acquisition unit capable of recording at speeds of up to 400,000 samples per second continuously to disk (aggregate). PowerLab units are compatible with instruments, signal conditioners and transducers supplied by ADInstruments, as well as many other third-party companies. In addition to standard single-ended BNC inputs, 4 differential Pod ports are also available for direct connection of Pod signal conditioners and appropriate transducers. Research PowerLab units include:

Research Systems

Mikro-Tip Pressure-Volume Systems

Instruments

Transducers and Accessories

Mikro-Tip Single Segment PV Catheters

Single Pressure:

Dual Pressure:

Mikro-Tip Multi Segment PV Catheters (dog/pig/sheep):

Mikro-Tip Multi Segment PV Catheters (rabbits/cats):

Other Accessories (purchased separately):

 

Microsomal Prostaglandin E2 Synthase-1 Deletion Leads to Adverse Left Ventricular Remodeling After Myocardial Infarction
Degousee N, Fazel S, Angoulvant D, Stefanski E, Pawelzik S-C, Korotkova M, Arab S, Liu P, Lindsay T F, Zhuo S, Butany J, Li R-K, Audoly L, Schmidt R, Angioni C, Geisslinger G, Jakobsson P-J, Rubin B B, Circulation, 1701-1710, 2008

Prevention of Dystrophin-Deficient Cardiomyopathy in Twenty One-Month-Old Carrier Mice by Mosaic Dystrophin Expression or Complementary Dystrophin/Utrophin Expression
Bostick B, Yue Y, Long C and Duan D, Circulation Research, 121-130, 2008

Measurement of cardiac function using pressure–volume conductance catheter technique in mice and rats
Pacher P, Nagayama T, Mukhopadhyay P, Batkai S and Kass D A, Nature Protocol, 1422-1434, 2008

Long-term cardiovascular effects of neonatal dexamethasone treatment: hemodynamic follow-up by left ventricular pressure volume loops in rats
Bal M P, de Vries W B, van Oosterhout M F, Baan J, van der Wall E E, van Bel F, Steendijk P, Journal of Applied Physiology, 446 - 450, 2008

Citations Database


The material on this page is provided in good faith and believed accurate at the time of writing. No responsibility will be taken, or liability accepted, for damages arising from the use of information herein. Readers are urged to check with respective manufacturers the accuracy of all product related information.

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