Selected one of Popular Sciences 50 Best of the Web.
Get Email Updates
Write to us and we will send you an email when a new feature appears on the site.
3D Heart (video)
August 14, 2001
Also on ScienCentral News
Mending Broken Hearts (video) - Scientists say experiments in mice show that a special sort of cell that we all carry around in our blood and bone marrow can rebuild damaged hearts, and probably other organs as well. (3/30/01)
Saving Hearts - Finding people at risk of heart attacks may soon be possible with a simple blood test. (12/21/00)
Virtual Surgeon - Some high-tech firms have partnered with medical schools in an attempt to revolutionize surgery training with virtual reality technology. (7/6/00)
Elsewhere on the web
American Heart Association
Watch Coronary Bypass Surgery
Heart Health from the Centers for Disease Control
The Cardiothoracic Surgery Network
Cut to the Heart - Nova Online
Women and Heart Disease - WebMD
Coronary heart disease is the number one health threat in America, with a variety of different heart surgeries performed every day.
As this ScienCentral News video reports, researchers are working on a system that could show surgeons the results of an operation without their ever lifting a scalpel.
When asked to list the leading causes of death, lots of people tend to go with whats in the news: AIDS, breast or lung cancer, even murder. But across all ages, races, and genders, heart disease actually kills the most Americans each year. While the second-leading cause of death (all types of cancer combined) only claimed 200 lives out of each 100,000 in 1999, heart disease killed 267.
One form of heart disease, congestive heart failure, describes the reduced ability of the heart to pump as much blood as the body needs to function. It results from weakened heart muscle, which can be a consequence of blocked blood vessels, high blood pressure, or diseases of the heart muscle itself. The heart initially becomes enlarged as the muscles grow, working harder to pump the necessary blood. However, the muscles cant maintain such a workload and become overstretched and ineffective, but leaving the heart distended.
Heart failure leads to weakness, shortness of breath and swelling (edema) in patients with the mildest, most treatable cases. The most severe cases require a transplant, and the number of potential recipients far exceeds the number of available replacement organs each year. For those who cant get a donated heart, surgery to improve the hearts function is the next best option.
"We know that the size of the heart is directly related to patient mortalitythe longer they have the large heart with heart failure, the higher the chance that theyre going to succumb to the disease," says Dr. Mark Ratcliffe, chief of cardiac surgery at the San Francisco Veterans Administration Hospital and a professor at the University of California at San Francisco.
Since the patient has a heart chamber too big for the strength of its pump, the solution could be either to reduce the demands on the pump or increase its strength. Strengthening the pump would require replacing weakened muscle, which would in turn mean rewiring nerves, which even the most skilled surgeons cant yet do. So they must reduce the stress on the muscles, either by completely removing parts of the heart wall to make it smaller or by reshaping the heart, changing the directions of stress.
Recently, Dr. Ratcliffe and his collaborator, Dr. Julius Guccione, assistant professor of surgery in residence at the University of California at San Francisco, studied the surgical removal of part of the heart wall and muscle to reduce the size of the heart. Using a modeling system to simulate the heart and its pumping capabilities, they found that no amount of wall volume reduction improved the hearts performance after heart failure. A December 2000 report in the Journal of the American College of Cardiology confirmed these results with a clinical study of the Batista procedure (named after its inventor, Brazilian surgeon Dr. Randas Batista) in patients.
But procedures and devices that reshape the left ventricle, the most commonly affected of the four chambers in heart failure, proved to be much more effective in the simulations. The Myocore Myosplint procedure puts three tension rods through the ventricle that can be lengthened or shortened, much like a shower curtain rod. Surgeons shorten the rods, shrinking the ventricle and constricting it in the middle, "like a dumbbell," Dr. Guccione says. The heart ends up smaller and the new shape changes the forces on the muscles.
Another option, aptly named the Acorn Cardiac Support Device, encases the heart in a mesh sleeve much like an acorn jacket encases its seed. The mesh restricts the heart from enlarging further in moderate cases of heart failure, and potentially even reduces chamber size. This device also performed better than the tissue removal forms of heart volume reduction surgery in Guccione and Ratcliffes tests.
Every individual has slight variations in heart size and shape to begin with, and these differences can become exaggerated with enlargement and disease. Finding what shapes and sizes respond best to which of these and other proposed devices and procedures will be the next step in customizing treatment for each patient.