Education
The conductance catheter is an invaluable tool used to measure real-time changes in cardiac chamber volume. Paired with a solid-state pressure sensor, the combination pressure-volume catheter provides researchers the opportunity to study ventricular pressure-volume relationships. The characteristic pressure-volume (PV) loop can be used to assess baseline hemodynamics like stroke volume, ejection fraction and cardiac output as well as load-independent measures of function including the end-systolic pressure volume relationship (ESPVR) and the end-diastolic pressure volume relationship (EDPVR). These two variables are considered by many to be the only way to study contractility of the heart.
The concept of correlating changes in conductance, or impedance, to cardiac volume has been explored since the beginning of 20th century. It wasn’t until the early 1980’s that a catheter was proposed to measure LV volume in the intact beating heart (Baan et. al, Cardiovasc. Res. 1981: 15, 328-34). Dr. Baan developed a catheter with pairs of excitation and recording electrodes to measure instantaneous changes in blood conductance and proposed a formula (appropriately termed Baan’s Volume Equation) to correlate measured conductance to volume.
Until recently, the conductance catheter technique for measuring ventricular volume has been limited to larger animal models and to the human cardiac catheterization lab. The challenge for technology companies has been to miniaturize such a powerful technology such that conductance volumetry could be applied to small rodents – clearly the predominant species in the world of basic cardiovascular science research. In 2002, Scisense introduced the world’s smallest conductance catheter for use in mice at only 1.2 F in diameter. Today, our line of products include single segment conductance catheters for use in mice and rats (1.2 F – 1.9 F), Variable Segment Length catheters for use in rats and rabbits (1.9 F – 3.0 F) and multi-segment conductance catheters suitable for larger animal models (5.0 F – 7.0 F).
Most recently, Scisense introduced the world's first and only admittance-based PV loop system which accurately, reliably and repeatedly measures absolute ventricular volumes in real-time. Our ADVantageTM PV loop system offers significant advantages over classical consuctance systems which include:
- no hypertonic saline bolus required
- no blood-cuvette calibrations necessary
- catheter position feedback
- calculation of time-varying changes of parallel conductance
The conductance catheter has been extensively validated in a variety of animal models against angiography, echocardiography, magnetic resonance imaging, dimension crystals and ventricular casts.
Scisense also offers innovative hardware and software solutions and acts as a sole source for an integrated PV setup.