These instruments provide a means for applying extravascular pressures (EvP) to excised, cannulated and pressurized vessels mounted in a sealed chamber. In particular, for cardiac, skeletal muscle and other vessels subjected to sustained or pulsatile pressures from the muscular tissue in which they are embedded. Studies can be carried out on these vessels to determine whether the functional changes that often occur may have local or distal significance in cardiovascular disease, and for analyzing underlying mechanisms.

The pressure control unit (EV-1) produces selectable, sustained EvP when used alone, and acts as an intermediate link allowing the signal generator (SG-1) to create sinusoidal and pulsatile extravascular pressure waveshapes. The sealed vessel chamber with or without the self-heating capability (CH-1-AU), is a key component of this system.

The fundamental source of system pressure is a laboratory compressed gas tank with a regulating valve (user supplied) for reducing the pressure to 6–8 psi. It is then modified by signals received from the EV-1 via the electronic servo valve to create the desired steady or non-steady extravascular chamber pressures. The servo valve is included with the EV-1.