By EurekAlert
Monday, September 14, 2009
BETHESDA, Md. (September 14, 2009) – Fifty-one years ago
the average American home cost $30,000, Elvis Presley wooed
listeners with Hard Headed Woman, and the hula hoop was introduced.
That same year, 1958, a team comprised of a groundbreaking engineer
-- Dean Franklin -- in concert with two exceptional physicians --
Drs. Robert Rushmer and Robert Van Citters – was laying the
foundation for what would eventually become a radical new approach
to health care: the noninvasive imaging and treatment of the heart.
The discoveries of these pioneers would eventually lead to a
doctor's ability to see the heart without cutting open the body;
allow patients to have their hearts monitored despite being miles
away; and provide reassurance to parents that a fetus' heart was
normal rather than waiting until the offspring was born.
The details of these efforts are chronicled in a new article,
"Standing on the Shoulders of Giants: Dean Franklin and His
Remarkable Contributions to Physiological Measurements in Animals,"
by R. Dustan Sarazan and Karl T.R. Schweitz. The article appears in
the September 2009 edition of Advances in Physiological
Education (http://advan.physiology.org/cgi/content/full/33/3/144).
The American Physiological Society (APS; www.the-aps.org)
publishes the quarterly journal. The APS has been an integral part
of the scientific discovery process since it was founded in
1887.
Dean Franklin: Ultrasound, Ultrasonic Transit Flow Meter, and
Doppler Flow
Dean Franklin was a teenager during World War II, but was
drafted in 1950 and selected for training in radar. He subsequently
became chief instructor in the U.S. Army's advanced radar school.
In 1952, he was recruited by Boeing to work on the BOMARC missile
project and was later hired as an electronics technician in the
laboratory of Robert Rushmer at the University of Washington
Medical School.
Initially, Franklin's role was limited to fabricating the
Whitney gauge, a relatively crude device that could be attached to
a dog's heart tissue to measure cardiac dimensions. At the time,
Rushmer was pioneering the concept of collecting cardiovascular
data from conscious animals with implanted instrumentation, instead
of the unconscious, open-heart animals that were the standard.
While working in Rushmer's laboratory Franklin melded what he
learned about the cardiovascular system with what he had learned
about radar during his military service. With the support of Dr.
Rushmer, a pediatrician and physiologist with a great interest in
the heart, they were able to develop ultrasound instruments to
measure blood flow, despite the prevailing view of the late 1950s
that ultrasonic measurements of blood flow were impossible.
Franklin's device was successful enough to be among the first
breakthroughs to use ultrasound for physiologic measurements. It
was used, for the first time, on conscious animals and eventually
humans.
By 1962, Franklin and a colleague had invented the first fully
functional ultrasonic transit time flow meter, which measures blood
flow in intact arteries; the sonocardiometer, which measures the
dimensions of the heart; and the ultrasonic Doppler flow meter,
which measures the velocity of liquids containing suspended
particles such as red blood cells. As a result of these
developments, a new generation of scientists launched the first
noninvasive ultrasound imaging devices, which are now the industry
standard in human medical technology. These devices are descended
directly from Franklin's first flowmeter and sonocardiometer.
Scripps Clinic and the San Diego Zoo
That same year, Franklin joined Robert L. Van Citters at the
Scripps Clinic in San Diego and established a relationship with the
San Diego Zoo. Through this arrangement, the researchers had their
first opportunity to work with animals other than dogs. While at
Scripps, Franklin designed and built the first telemetry device for
remote monitoring of physiologic signals (other than temperature).
It was first tested on an exercising boxer dog at the Zoo hospital
and subsequently was used for telemetry experiments in baboons and
a variety of other animal species across the globe. The telemetry
widely used in hospitals that we know today evolved from these
experiments.
Out of Africa, Into Alaska
After three years at Scripps, Franklin and Van Citters conducted
telemetered experiments in Kenya for the purpose of understanding
the effects of exercise in baboons in their natural habitat and the
unusual hemodynamic issues confronted by giraffes with the large
hydrostatic pressure gradient between their heads, their hearts and
their feet. The pair was successful in developing and implanting
tiny devices in the heart that the animals could wear for long
periods. The devices, small implantable blood pressure transducers,
Doppler flowmeters and a radio telemetry system, were surgically
implanted, the animals recovered and the experimenters were able to
carry out long distance monitoring of blood pressure in the
animals.
Franklin and Van Citters continued to focus more sharply on the
physiology of exercise, especially the distribution of blood flow
to various organs during extreme exercise. Classic physiology
predicted a reduction in renal flow during a fright reaction,
though in one of the African experiments, a baboon was threatened
by a giraffe but its renal flow did not change. Nor did it change
among treadmill-exercising dogs in experiments previously conducted
in Rushmer's laboratory.
Ultimately, Franklin and Van Citters used their telemetery
systems to study Alaskan sled dogs, similar to those in the famous
Iditarod race. They traveled to Alaska and instrumented several
dogs, surgically inserting flowmeters and pressure gauges. After
the dogs recovered from surgery and were reconditioned to their
previous exercise capacity, their performance was tested. They were
able to run 20 consecutive 4-minute miles without showing any sign
of exhaustion and no evidence of blood flow deficit to visceral
organs, even during extreme exercise.
SOURCE