working heart experiments

The working heart setup from emka TECHNOLOGIES contains all you need to run working heart experiments on hearts from mice, rats, guinea-pigs or rabbits.

The main goal of the setup is to keep the heart alive and maintain constant conditions while recordings are made. The heart receives oxygen and nutrients in the perfusate and is also maintained at a constant temperature.

In functional terms, the applications can be divided into two sub-systems: one for maintaining the heart alive, the other for acquiring signals.

The mainframe is the central component. It contains the heart chamber, which has been specially designed to provide easy access to the heart. Channels cut inside the mainframe walls form two separate circuits for, respectively, perfusate and heating liquid (usually distilled water).

subsystem: heart support

Several peripheral components are required to keep the heart alive and maintain constant conditions:

heater/pump: heats and pumps heating liquid through the mainframe. The heating liquid maintains the perfusate and the heart chamber at the required temperature.

pump: to push the perfusate from the reservoirs through the mainframe, to the heart chamber.

flow/pressure regulator: The fpr controls a peristaltic pump (to maintain perfusate flow rate or pressure constant) and opening/closing of valves (to determine direction of perfusate flow).

At the start of the experiment, you can mount the heart in constant flow mode. Once cannulas are in place, you can switch instantly to working heart mode (which is in fact a constant pressure mode in which afterload pressure is maintained constant).

carbogen bottle: tubes are placed inside perfusate reservoirs.

perfusate reservoirs: can be placed in the water bath of the heater/pump to preheat the perfusate before it arrives in the mainframe.

waste tank: for collecting used perfusate.

subsystem: acquisition

At least three transducers are required for working heart experiments.

The left ventricular pressure is measured by a pressure catheter inside the left ventricle. emka TECHNOLOGIES can supply the Mikrotip pressure catheter (Millar), for this purpose, and the adapter cable for connecting it to a bridge amplifier module. The module is fitted inside a mainframe, which is connected to the interface box.

Two other pressure transducers measuring preload and afterload perfusate pressure are connected to the flow and pressure regulator. The fpr has to know the afterload pressure for working heart mode; the preload pressure is simply passed on further down the acquisition chain, to the interface box.

A single cable from the interface box carries all signals to the acquisition card of the computer.

Data acquisition and real-time analysis with the lvp analyzer can be done with iox software.

parameters

In the system described above, iox software receives 5 signals: target afterload pressure, measured afterload pressure, preload pressure, flow rate (directly proportional to the pump speed- in other words, a flowmeter is not required) and the left ventricular pressure.

Other signals may be acquired, particularly ecg. In this case, the electrodes are connected directly to other amplifier modules inside the same mainframe. For example, a 1-lead ecg module is required if three electrodes are used.

Please contact us for further information about running working heart experiments.