EVOLUTION has favoured cockroaches above human beings, at least when it comes to the functioning of the heart. A cockroach's heart will continue to beat even when one of its chambers has failed; in similar circumstances, a man will die. Now a team led by Sujoy Guha of the Indian Institute of Technology, Kharagpur, has created an artificial human heart based on a cockroach's, which they believe will be unusually robust and affordable.
A cockroach's heart is a tube that runs the length of its body. It has 13 chambers, linked like a string of sausages. As each chamber contracts, the blood within is pumped to a higher pressure. Each successive chamber increases the pressure. A human heart, by contrast, has four chambers. Two of these pump blood to the lungs, where it picks up oxygen, then the other two pump this oxygenated blood throughout the body. One of these four chambers—the left ventricle—contracts most strongly to pressurise the blood.
The artificial hearts developed so far have mostly mimicked human ones. The first devices, developed in the 1950s and 1960s, were large machines placed on trolleys next to the patient and attached by tubes. Modern artificial hearts are less cumbersome, but they are still rather unwieldy because they use compressed air to pump the blood and are powered by heavy batteries. They are used temporarily, usually for a few days or weeks, until a real heart is available for transplant.
Instead of trying to mimic the action of the left ventricle, Dr Guha's design uses a multi-step approach borrowed from the cockroach. His device, made from plastic and titanium, is the same size as a human heart but with five chambers arranged like the layers of an onion. Each chamber acts in succession to increase the pressure of the blood. The contraction of each chamber is controlled by a motor driven by bulky batteries. The artificial heart is being tested on goats, with human trials scheduled for next year. If these are successful, the device could be on the market in three to five years.
The multi-step approach makes this artificial heart much cheaper to build than those that use compressed air to pump the blood. Dr Guha says it would cost $2,000-2,500. Peter Weissberg, medical director of the British Heart Foundation, says one reason clinical trials of artificial hearts are so difficult to conduct is that the devices are so expensive, typically costing over $50,000. Dr Guha's cockroach-inspired artificial heart promises to provide an affordable option for cardiac care in emerging economies such as India, where heart disease is on the rise.