1. Field
The present invention relates to apparatus and methods for driving a pneumatically operated implantable device, such as an artificial heart.
2. Discussion of Related Art
Artificial hearts are typically constructed with right and left ventricles that function generally like and may replace the right and left ventricles of a native heart. The right ventricle receives oxygen-poor blood from the subject's body and delivers this blood to the lungs for oxygenation. The left ventricle receives oxygen-rich blood from the lungs of a subject and delivers this blood throughout the subject's body.
Each ventricle of the artificial heart 100, like that shown in FIG. 1, includes a movable diaphragm 102 that is positioned between an air chamber 104 and a blood chamber 106 within the ventricle. The air chamber includes a single inlet/outlet 108 that is in fluid communication with a pneumatic driver. A blood inlet valve 110 provides a one-way entrance into the blood chamber 106 from the circulatory system of a subject and a blood outlet valve 112 provides a one-way outlet from the blood chamber.
To replicate the systole of a native heart, pressurized air is provided to the air chamber in each ventricle of the artificial heart. The pressurized air displaces the diaphragm within the ventricle, reducing the volume of the blood chamber and causing blood to be ejected through the outlet valve and into the circulatory system of the subject. To replicate the diastole of a native heart, pressure is relieved from the air chamber of the ventricle, which allows blood to enter the blood chamber from the circulatory system of the subject.
One example of an artificial heart is the CARDIOWEST Total Artificial Heart (TAH-t), as illustrated in FIG. 1. The TAH-t has left 114 and right 116 ventricles with a displacement of 70 cubic centimeters each. The TAH-t is used as a bridge-to-transplant type device, whereby the TAH-t is configured to replace a diseased heart on a temporary basis until a subject receives a transplanted human heart. The TAH-t may potentially, however, also be used as a permanent replacement for a native heart.