CVSim: a cardiovascular simulator

Please cite reference 1 below as well as PhysioNet in any publication for which you have used this software. If you teach using CVSim, please tell us about your course. The CVSim software was developed between 1983 and 2007, and four versions of it are available from PhysioNet: XCVSim (1991-1998), a 6-compartment model with an X11 GUI RCVSim (2000-2003), a 6-compartment model with a scriptable command-line interface CVSim-6 (2002-2007), a 6-compartment model with a Java GUI (described below) CVSim-21 (2002-2007), a 21-compartment model with an enhanced Java GUI (also described below)

CVSim is a lumped-parameter model of the human cardiovascular system that has been developed and used for research and for teaching quantitative physiology courses at MIT and Harvard Medical School since 1984. The versions presented here have a graphical user interface implemented in Java, with computational components in C. The portable C code has been compiled for popular platforms, and users of Linux (x86), Mac OS X (PPC and x86), and MS Windows (x86) should be able to use the links below to run CVsim.

CVSim requires the 32-bit Sun/Oracle Java Runtime Environment (JRE 6), running on a 32- or 64-bit version of Linux, Mac OS X, or MS-Windows. CVSim is not currently supported by 64-bit versions of the JRE, by any version of OpenJDK (IcedTea), or on Solaris.

CVSim has been tested successfully using JRE 6 on Windows XP (32), Windows 7 (32 and 64), Mac OS X (PPC, x86, and x86_64, 32-bit versions 10.4 and 10.5, and 64-bit 10.6), and many versions of 32- and 64-bit Linux including Fedora (4 through 14), Red Hat Enterprise Linux 4, and Ubuntu 8.04.

Prerequisites for the Educational Version of CVSim (CVSim-6)

In order to run the educational version of CVSim, Java Web Start must be installed on your computer. Since it is included in all recent versions of the Java Runtime Engine (JRE), this may have been done already. If not:

Linux: Install a 32-bit version of JRE 6 (or JDK 6, which includes JRE 6) from oracle.com or java.sun.com, then follow the instructions on oracle.com or java.sun.com to install the Java plugin in your web browser.
Mac OS X: Run Software Update from System Preferences. Install Java for Mac OS X. (If 64-bit versions become available, you will need to select a 32-bit version.)
Windows: Install a 32-bit version of JRE 6 (or JDK 6, which includes JRE 6) from oracle.com or java.sun.com.

Some 64-bit browsers (such as 64-bit versions of IE 8) are incompatible with 32-bit versions of Java. If this is the case for your browser, install and use a 32-bit browser in order to install the 32-bit JRE and launch CVSim. You do not need to change your OS or remove your 64-bit browser in order to do so.

You need to do this at most once on any computer on which you will use CVSim. Restart your browser after installing or updating Java.

Launching the Educational Version of CVSim

Once Java Web Start has been installed on your computer, one of the two links below can be used to start CVSim.

Launch CVSim [physionet.org]      Launch CVSim [alternate]

PhysioNet mirror users: Try the alternate link first. If it doesn't work, the first link can be used to launch CVSim from the master PhysioNet server.

The first time you run CVSim, a warning will appear. (Internet Explorer users: The security warning may be displayed behind your browser.)

Click Run. (To avoid the warning in the future, first check Always trust content from this publisher).

IcedTea Web Start: On Linux (and perhaps on other platforms), your browser may suggest launching CVSim using the IcedTea Web Start application. Try it if you wish, and please let us know if you are successful; as of this writing, we have not had success using IcedTea Web Start and we have not heard from anyone else who has. As noted in the previous section, the Sun (now Oracle) JRE 6, its Java plugin, and its Web Start application are known to work and are recommended. The Sun/Oracle Java Web Start application, javaws, is installed in /usr/java/jre1.6.n_nn/bin/javaws on Fedora Linux; this may vary on other platforms.

Research version of CVSIM (CVSim-21)

Sources for the research version of CVSim, which includes the six-compartment teaching model available above as well as a more detailed model containing 21 compartments, are available as a gzip-compressed tar archive, or you may get individual files from the source tree.

Precompiled binaries of the research version of CVSim are also available for GNU/Linux and Windows. (These binaries must be downloaded and unpacked before they can be run. Instructions for using them are included in each package.)

For reference, you may also wish to study an older implementation (see RCVSIM or XCVSim).

Using CVSim

The notes below apply to both the educational and the research versions of CVSim.

CVSim Window Components

The CVSim window is divided into four sections ("panes") and a toolbar:

These components are briefly described here, and demonstrated in short Flash animations (click on the links below to see them).

Simulation Control Toolbar

The Simulation Control Toolbar includes six controls to stop and start the simulation and turn the control systems on and off:

	Start the simulation
	Stop the simulation
	Turn on the arterial baroreflex control system
	Turn off the arterial baroreflex control system
	Turn on the cardiopulmonary reflex control system
	Turn off the cardiopulmonary reflex control system

Simulation Parameters Pane

The Simulation Parameters Pane displays the simulation variables and outputs. (The Simulation Outputs Pane, which is located on a separate tab behind the Simulation Parameters Pane, is not functional in the current version of CVSim. In a future version, it will be used to select outputs to be recorded in a log file.)

Graphics Pane

The Graphics Pane displays anatomical and circuit representations of the simulation model.

Click and drag the vertical bar between the Simulation Parameters and Graphics panes to resize them.

Strip Chart and Plot Panes

The Strip Chart behaves like a chart recorder, plotting simulation outputs versus time and scrolling from right to left. The Plot Pane behaves like a flatbed XY plotter, plotting simulation outputs versus one another. Watch the Strip Chart and Plot demo.

Strip Chart and Plot panes can be undocked using the arrow icon at the upper right corner of the pane. Once undocked, they can be moved and resized, and it is possible to view more than one of each simultaneously. (Select New Strip Chart or New Plot from the main window's Plot menu to create additional strip charts or plots.)

Printing

There is no built-in facility for printing. Linux users can take a snapshot of the screen using the PrintScreen key, or of a single window (such as an undocked strip chart pane) using Alt+PrintScreen. Most image viewers (such as eog, gimp, gqview. or kview) can display and print these snapshots. Similar facilities may be available on other platforms.

Differences Between the Educational and Research Versions

The educational version includes the six-compartment model only, and there are minor user-interface differences with respect to the research version. Notably, the menu bar of the educational version includes a Patient menu; selecting a patient allows a student to explore what perturbations of cardiovascular parameters might account for a given set of symptoms, and what interventions might be effective in improving the CV state of the virtual patient. The research version includes both 6- and 21-compartment models (you must choose one of these at the beginning of the simulation), and offers greater flexibility in performing experiments using the model. The current research version allows the user to perform virtual tilt tests, for example.

Acknowledgments

This implementation of CVSim is the work of Catherine Dunn and Thomas Heldt, with contributions from Ali Saeed and Brandon Pierquet.

Previous implementations were written by Bob Sah (1983), George Moody (1985), Tim Davis (1989), Rama Mukkamala (2001), Thomas Heldt (2002), and by Eun Bo Shim and his students (2003). The circulatory model used in CVSim was created by Roger Mark, based on an analog model of JG Defares and colleagues [2]. The CVSim model was elaborated by Thomas Heldt, Eun Bo Shim, Roger Kamm, and Roger Mark [3].

Development of CVSim was supported in part through the National Aeronautics and Space Administration (NASA) Cooperative Agreement NCC 9-58 with the National Space Biomedical Research Institute (grants CA00106, CA00205, and CA00403).

References

[1] T Heldt, R Mukkamala, GB Moody, and RG Mark. CVSim: An Open-Source Cardiovascular Simulator for Teaching and Research. Open Pacing, Electrophysiol & Ther J 3:45-54 (2010).

[2] JG Defares, JJ Osborne, and HH Hara. Theoretical synthesis of the cardiovascular system. Study I: The controlled system. Acta Physiol Pharmacol Neerl 12:189-265 (1963).

[3] T Heldt, EB Shim, RD Kamm, and RG Mark. Computational modeling of cardiovascular response to orthostatic stress. J Appl Physiol 92(3):1239-1254 (2002 March 1).

Related Links

• A Cardiovascular Simulator for Research. RCVSIM is Rama Mukkamala's 2001 version of the CVSim model, and was developed using MATLAB. MATLAB is not required to run RCVSIM under Linux. The output of RCVSIM can be read and manipulated further using the WFDB software package.
• XCVSim. Sources and Linux binaries for Tim Davis's 1989 implementation of CVSim for X10 on MIT's Project Athena, with revisions by George Moody for X11 on GNU/Linux and other Unix platforms.
• Quantitative Physiology: Organ Transport Systems. This MIT OpenCourseWare course is based on Roger Mark's spring 2004 course, which used XCVSim. CVSim-6 was first used in this course in spring 2007.