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Model-7 ALVAD
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Model-7 ALVAD
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This device is described here for historical purposes. It is no longer in use.

Between 1975 and 1978, Dr. John Norman and Dr. Denton A. Cooley performed a series of implantations of a pneumatic (air-driven) abdominal left ventricular assist device (ALVAD). The Model-7 ALVAD was used to support post-cardiotomy patients (those whose hearts had failed after heart surgery). The device was evaluated in 22 patients at the Texas Heart Institute.

In February 1978, Drs. Cooley and Norman implanted a Model-7 ALVAD in a 21-year-old man whose left ventricle deteriorated after he had double heart-valve replacement. The Model-7 ALVAD kept this patient alive until he underwent heart transplantation 5 days later. Unfortunately, he died of infection after his transplant.

This clinical trial at THI was the first sponsored by the National Institutes of Health to determine the effectiveness of support with a  left ventricular assist device. These and other trials of the ALVAD demonstrated that patients' hearts could be supported with the use of a left ventricular assist device and led to the development of  more sophisticated pumps.

Diagram of the Model-7 Abdominal Left Ventricular Assist Device (ALVAD)The Pump

The Model-7 ALVAD is a pneumatic, single-chambered implantable blood pump that was placed in the abdomen and connected to the left  ventricle by a Dacron™ tube.  Blood from the left ventricle flows through the tube and fills a polyurethane bladder. When air from the drive-line fills the space between the bladder and the titanium pump housing, the blood is pumped through a disc-type valve into the aorta and to the  body. Polyester fibers coat all of the blood-contacting surfaces, except the valve discs and the inflow and outflow grafts. The fibers promote  the development of a cellular lining, which helps prevent blood clots and infection.

The Console

The console provides variable settings of pump chamber pressurization, pump chamber filling,  and pulse duration. The two modes of operation include EKG-triggered pumping (synchronized with the resting and pumping phases of the left ventricle) or variable fixed-rate asynchronous pumping. Four fail-safe functions are also available in cases of EKG interruption; mechanical or electrical failure; loss of external pneumatic power; or loss of AC line power. The internal power supplies allow for portable operation for up to 50 minutes.

For more information, you can read an article entitled, "Intracorporeal (Abdominal) Left Ventricular Assist Devices or Partial Artificial Hearts: A Five-year Clinical Experience," which appears in Volume 116 (1981) of the Archives of Surgery (pp. 1441-1445).

 

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