Biomedical Engineering Reference
In-Depth Information
inflow tracts (atria), and the outflow tracts were lined with a special fabric that promoted the
formation of a smooth cellular surface (pseudoneointima-forming surface). The flexible
inflow and outflow tracts were made of Dacron fabric, and the pump chambers were made
of a combination of Dacron fabric and Silastic.
The pumps were connected to the external power unit with Silastic tubing covered by
Dacron. The console, also a major engineering accomplishment at the time, was about the
size of a large washing machine. Two pneumatic power units generated the pumping and
vacuum actions needed to move blood through the artificial heart. An adjacent control panel
could be used to adjust pumping rate and pumping pressure (Cooley, Liotta et al., 1969).
Although Karp died of kidney failure 3 days after receiving a real heart, the procedure
demonstrated the viability of artificial hearts as a bridge to transplant (BTT) in cardiac
patients. However, some criticized the surgery as unethical because it was performed
without formal review by the medical community.
Karp was the only person ever to have a Liotta-Cooley heart implanted, and even
though it was a success at sustaining the patient until transplantation, many scientists con-
sidered this step of technology too risky. As a result, enough controversy ensued to post-
pone the use of artificial hearts for the next 20 years. During this hiatus, the development of
LVADs was pursued aggressively, and it was only in 1981 that Cooley again demonstrated
the potential of a TAH when an Akutsu-III was implanted to provide temporary support
until a suitable donor could be located.
8.4.1.2 The Jarvik-7 Artificial Heart
In 1967, Kolff left Cleveland Clinic with engineer Thomas Kessler and surgeon Clifford
Kwan-Gett to start the Division of Artificial Organs at the University of Utah. Initial
animal trials were not very successful. Even as late as 1970 the best he had managed was
a sheep that lived 50 hours with an artificial heart, and it could hardly even lift its head.
The Jarvik-3, developed in 1972, was the first of the range developed as a human implant.
Cows implanted with these devices lived for up to 4 months with little or no medical
intervention. By 1976 the design had been further improved, and the Jarvik-7 had kept a
calf alive for 268 days (Hajar, 2005). Three years later, when surgeon William DeVries
returned to Utah, animals were walking around, and, according to DeVries, they looked
normal except that they were connected to a machine. He was certain that the time was
ripe to initiate human transplants.
DeVries spoke to the technician who had made hundreds of excellent artificial hearts
for animals, but he was reluctant to move on to human trials, saying, “My God, I can't do
that; these are just for animals. I can't do that. I mean, I can't make one good enough.”
However, in the end he was persuaded, and in 1982 he and Lyle Joyce implanted the
Jarvik-7 in implanted in Barney Clark, a Seattle dentist (Hajar 2005).
Clark, who due to his age and severe emphysema had not been a candidate for a
transplant operation, was never able to leave the hospital. The system was open to infection,
so Clark and subsequent Jarvik-7 recipients got sick. Patients had to be kept on blood
thinners to prevent clots and strokes. Although Clark was reported to be in stable condition
48 hours after the implant, his subsequent postoperative condition was not good (Hajar,
2005):
•
Day 3: He underwent thoracic exploratory surgery because of subcutaneous
emphysema.
•
Day 6: He had generalized seizures that left him in a coma.
