Vol. 38, No. 18

3-1-2006
By: Holly Wagner

Hamlin takes envy to heart during Distinguished Lecture

If the Tin Man had heard Robert Hamlin's University Distinguished Lecture Feb. 15, perhaps he would have included a few extra details in his request for a heart.

Many animals possess amazing physical and physiological abilities. If humans had these same attributes, no one would suffer from heart failure, Hamlin said. Physicians could forgo fancy machines and instead emit their own high-frequency sound waves to detect abnormalities in heart function. And fighter pilots could tolerate enormous rates of acceleration without fainting during flight.

Hamlin, a professor of veterinary biosciences and a heart expert, explained to a rapt audience at the Wexner Center Film/Video Theater why, if "slightly" modified, giraffes would make great fighter pilots and bats would make excellent cardiologists. He also divulged the reasons behind his own desire for a heart that is part guinea pig, part spider and part goat.

"It's lucky we're so smart," said Hamlin, suggesting that humanity's technological prowess has, to some extent, given us the capability to act, well, like animals.

Take the fighter pilot. During flight, he wears a G-suit, or antigravity suit, to sustain extremely high gravitational forces when turning sharply or coming out of a dive. If the pilot didn't wear the tight, inflatable suit, blood would pool in the legs and buttocks and wouldn't be returned as quickly to the heart or pumped to the brain, causing him to faint.

In contrast, a drinking giraffe can lifts its head some 17 feet in a matter of seconds without fainting. Tight, thick skin covering its legs and neck prevents blood from pooling in the animal's legs and instead keeps the blood flowing to the heart and brain.
"What a great fighter pilot he would be," Hamlin mused. "Of course, the giraffe could never hold his head up under that kind of gravitational force. And he's just a little too tall for the cockpit."

Bats as heart specialists
The bat's aptitude for identifying even the smallest structural features and motions is far better than the capabilities of even the most sophisticated echocardiography, or ECG, machine, which uses ultrasound waves to make images of and measure blood flow in the heart.

"Physicians can't see what's wrong with a heart, so they use a big, expensive and time-consuming piece of equipment to do the job," Hamlin said. "The bat, however, would make an excellent cardiographer, but it would probably scare patients."

The ideal heart
Heart disease causes about 60 percent of all deaths in the United States. Coronary artery disease - when the arteries that nourish the heart with oxygenated blood become clogged and prevent blood flow to a region of the heart - is the most common form.

But the heart of a guinea pig has an enormous intersecting grid of arteries. Even if two or three of its major arteries become obstructed, the flow from nearby vessels is more than adequate to sustain the heart perfectly, Hamlin said.

One of the most common causes of heart failure is that the heart becomes stiff and, as a result, doesn't fill well. The human heart fills passively, relying on the weight of blood pushing in from the lungs. But a spider has muscles that actively pull open the ventricles, the chambers that fill with blood during a heartbeat.
"These muscles actually pull the heart open after a contraction," Hamlin said.

Finally, human hearts are stimulated by a slight electrical shock wave that travels across the cardiac muscle. But if part of the pathway that carries this signal becomes blocked, the heart won't contract properly. Yet if the same thing happened inside a goat's heart, it wouldn't skip a beat because the goat heart has a rapid-fire conduction system that sends the electrical signal along the heart at a much faster rate than the human heart. And in the goat heart, this electrical signal will work around the blocked area.

While we don't have the advantages of some animals, Hamlin said it's our smarts that keep us going and going. We have access to excellent health care, we have minimized the risk of death from infection and most of us are no longer prey for hungry four-legged predators.

And - take this as you will - it may not be too far-fetched, or too far off, to consider that humans may be genetically engineered to have such attributes as some animals, Hamlin said.

The University Distinguished Lectureship recognizes outstanding faculty at Ohio State, giving recipients the chance to discuss their work with the community and a $5,000 award to support an academic program or project of the lecturer's choice. Hamlin is using his award in support of graduate studies in veterinary biosciences.

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