Heart-lung machines can be used for another purpose: After snowmobilers fall through the ice, they may arrive at a hospital with a body temperatures in the teens (Celsius). Surprisingly, due to a little-understood phenomenon called the "mammalian diving reflex," they do not die, even though their hearts have stopped beating. The fastest way to warm up the body is to route blood from a vein into the heart-lung machine, and back to an artery. "Sometimes," the heart-lung machine's operator says, "they seem to do fine" after the ordeal.

The aorta at the top center of this double-bypass operation is connected to two grafts. One graft supplies the anterior descending branch of the left coronary artery. The other supplies the right coronary artery. © 1996 University of Wisconsin-Madison Medical School, Joan Kozel, illustrator. 11:01The transducers (defined) that measure arterial and venous blood pressure are reading erratically, and Love instructs the anesthesiologist to flush them out by running a solution through them. Love adds ice to the chest. 11:13A low-tech moment in a high-tech operating room: The anesthesiologist checks Smith's pupils, and finds them small and of equal size. That's reassuring -- anything else can indicate brain damage, or bad circulation.

11:20 The surgeons have finally started the heart of the operation -- connecting the grafts. As they work, blood that leaks into the cavity around the heart is sucked into the heart-lung machine and returned to circulation.

11:25 The first graft to a difficult-to-reach artery on the right side of the heart, is connected.

11:35 "We don't have much vein," Love observes, and he stretches it out to figure how to use it most efficiently. He watches the surgical fellow delicately sew the second graft to the circumflex artery.

12:01 With the operation moving into its fifth hour, the surgeons are searching for the left anterior descending artery, which supplies the essential left ventricle -- that's the chamber that pumps blood out for its long trip through the estimated 100,000 miles of blood vessels in the body.

The heart is padded with fat -- showing on its surface what is likely harming it from the inside. In fact, the whole operation is starting to look like a long advertisement for the kind of low-fat eating that can often prevent artery damage in the first place. The fat makes it hard for these two surgeons to locate the artery, and they momentarily resemble baffled medical students in their first anatomy class.

12:05 The artery located, Love starts cleaning up the end of the internal mammary artery which will feed it. Unlike the veins they've been using until now, this artery can remain connected at its supply end, thus simplifying the operation somewhat.

12:21 "That was a pain," Love mutters, as they finish sewing the mammary artery. They turn to connecting the vein grafts to the aorta, which normally supplies the heart's arteries. That, he says, will be "more challenging than usual" because the heart has been enlarged after years of heart disease and the aorta is calcified and brittle due to the patient's kidney failure. Here's a great drawing of the heart's arteries and veins.

By now, the job is almost sewn up.

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