PASADENA, Calif.--If you're a squid, your typical day consists of leisurely squirting water behind you to move forward, and occasionally squirting larger quantities of water behind you to stay off someone else's lunch menu. If you're a human with heart disease, your day consists of pumping blood through your heart valves much more forcefully than you did when you were young and healthy.
Is there any fundamental connection between these two seemingly dissimilar events? The answer is turning out to be yes, and moreover that a better understanding of what they have in common could lead to a new and improved diagnostic tool for heart disease.
In a new paper in the Proceedings of the Royal Society, California Institute of Technology engineers John Dabiri and Mory Gharib report on their work in understanding the fundamental nature of biological fluid transport. Specifically, they look at the way that vortex formation is optimized and controlled by various organisms, and how jets of fluid can be manipulated to affect energy transport and system efficiency.
"Heart disease typically manifests itself in problems with fluid transport, so if we can learn general principles of effective fluid transport from other animal systems, then we can potentially identify new strategies to diagnose and treat heart failure," says Dabiri, who recently joined the Caltech faculty as an assistant professor of bioengineering and aeronautics. Gharib, who was Dabiri's graduate adviser at Caltech, is the Liepmann Professor of Aeronautics and Bioengineering.
The researchers' strategy is to apply the same principles that have gone into the refinement of airplane and spacecraft designs to matters of biomedical concern. The landing of a space shuttle and the operation of a human heart may seem unrelated, but the fluid flow involved in both cases obeys the same general physical laws. Therefore in both instances one can apply "reverse engineering," in which one looks at a complex system already in existence and tries to understand its fundamentals.
In the case of biological fluid flow, scientists know that a number of animals regularly manipulate jet flows for their survival. Therefore, trying to understand precisely how these jet flows function can lead to a new way of understanding how to fix the individual parts that are broken.
"If you can figure out the basic design principles that allow the left ventricle to function well in terms of fluid transport, then creating therapies for disease may not be much different from redesigning an airplane wing for improved performance using the appropriate aerodynamic principles," Dabiri says.
Since many kinds of heart disease are known to be reflected in blood flow near the heart valves, Dabiri, Gharib, and Dr. Arash Kheradvar, an MD who is working for his Ph.D. in Gharib's group, hope to be able to determine the overall health of the heart by viewing this smaller subsection. The diagnostic procedure might turn out to be as simple as taking an echocardiogram of a patient's heart-in much the same way that a sonogram is currently taken of a pregnant woman's abdomen to monitor the health of a fetus.
Then, if a problem with the jet flow through the valve were to be identified, the discovered design principles could be used to direct surgeons on how to correct the malfunction.
Further laboratory and clinical research is needed before the current results will translate into such a practical diagnostic tool, Dabiri says. However, this study takes an important step toward this goal by developing the paradigm under which future research will proceed.
