Monday, February 7, 2005

The world of cardiac care has come a long way since the first open-heart surgery, says Dr. Vincent Gott, professor of cardiac surgery at Johns Hopkins Hospital in Baltimore. As an intern at the University of Minnesota in March 1954, Dr. Gott witnessed one of the original groundbreaking procedures.

“One hundred years ago, doctors thought it would never happen,” Dr. Gott says. “In late 1953, no one ever thought that open-heart surgery for complicated defects might be successfully accomplished.”

Since his days as an intern, Dr. Gott has performed nearly 4,000 heart operations. He is excited about the ongoing developments in cardiology.

Gone are the days of simply solving most major heart problems by opening the patient’s chest. Advancements continue to make surgery safer, while some research aims to eliminate invasive procedures.

Various cardiac operations can be performed by using a robotic arm without spreading the patient’s ribs, says Dr. David Yuh, director of cardiac surgical research at Hopkins Hospital.

The robotic arm is run by a surgeon at a remote computer station. The computer transmits the surgeon’s movements while reducing the tremors of human hands.

The technology is used for procedures such as repairing mitral valves, performing limited coronary bypass operations, closing atrial septal defects and placing pacemaker leads.

“You don’t have to make a big cut to poke the robotic hands in there,” Dr. Yuh says. “Because you’re not making a large incision, you’ll have quicker patient recovery.”

Aside from robotic surgery, cellular regeneration therapy could change the future of cardiology, says Dr. Joshua Hare, director of the cardiovascular section of the Institute for Cell Engineering at Johns Hopkins Hospital.

Dr. Hare recently repaired pig hearts damaged by heart attacks. He injected stem cells from pig bone marrow into the damaged hearts. Within two months of the therapy, the pigs’ heart function was completely normal.

Dr. Hare plans to start a clinical trial using the procedure in humans during the next year.

“Heart attacks are the number one medical problem in the United States,” Dr. Hare says. “One day, cellular regeneration may be an outpatient procedure to treat them.”

Along with bone marrow, the heart itself may provide stem cells that aid in healing a damaged heart, says Dr. Eduardo Marban, Hopkins’ chief of cardiology. He has grown stem cells in the laboratory from a tiny piece of human heart tissue taken during a routine biopsy. Dr. Marban plans to run a clinical trial in pigs and mice to see if injecting human heart stem cells into the hearts of pigs or mice can aid in repairing the animals’ scarred organs.

“This is going to revolutionize the way we take care of heart patients,” Dr. Marban says. “It’s the idea that we can isolate stem cells from a patient’s own heart and reintroduce them. It’s a once-radical notion that we are about to reduce to practice.”

It is hoped that within the next two years, patients routinely will be receiving cellular regeneration therapy, says Dr. Richard Lange, chief of clinical cardiology at Hopkins. He anticipates putting stem cells from bone marrow or heart tissue into patients during bypass surgery. The cells also could be given to a person through catheters.

“Since nine out of 10 transplant patients die waiting for transplants, we are set on changing the way cardiology is practiced,” Dr. Lange says. “We hope this will replace heart transplants.”

Even when heart surgeries are performed, many of them have become more efficient, says Dr. Paul Corso, chief of cardiac surgery at Washington Hospital Center in Northwest. According to the Society of Thoracic Surgeons in Chicago, during the past 10 years, the mortality rate after coronary bypass surgery has been reduced from 3.5 percent to 2.5 percent.

Completing coronary bypass surgery without using a heart-lung machine is one of the recent advances, Dr. Corso says. He performs about 60 percent of bypass surgeries without the device, which shunts blood away from the heart during surgery, oxygenates it and returns it to the body.

“Some of the risk of the coronary bypass surgery comes from the machine,” Dr. Corso says. “Without the machine, there is an improvement in mortality, stroke, length of stay in the hospital and the number of blood transfusions because of surgery.”

In addition to advances with coronary bypass surgeries, stents containing medication and placed in the arteries have proved effective on a long-term basis, says Dr. Augusto Pichard, director of the cardiac catheterization lab at Washington Hospital Center.

The medicated stents are so helpful that they often eliminate the need for bypass surgery, he says. Drugs such as Paxil and Rapamycin can be delivered in the highest concentration to the place with the most blockage.

“The drug is infiltrated into a gel in the stent,” Dr. Pichard says. “The use of the newer stents allows us to treat more complicated blockages, which we often see in patients who have diabetes.”

While procedures with medicated stents are being done now, nanotechnology is likely to help cardiac patients in the future, says Denis Buxton, associate director of the heart research program at the National Heart, Lung and Blood Institute in Bethesda. Mr. Buxton holds a doctorate in biochemistry.

For instance, he expects that nanotechnology will deliver drugs exactly where they are needed in the body by targeting the medication to a specific site. He also anticipates that nanotechnology will be used in molecular imaging, which will better identify diseases.

Very small particles called nanoparticles would carry drugs and imaging agents, Mr. Buxton says. The particles also carry surface-bound antibodies that direct the particles to where they should attach.

For instance, antibodies might target plaque in the arteries and bind to it. The imaging agent would image the plaque while the nanoparticle delivered a drug to it. Because plaque rupture causes most heart attacks, if the plaque is stabilized with drugs, the patient would be less likely to have a heart attack.

The procedure also would allow new medicines to be used that previously might have been systemically toxic. If the drug is targeted to a certain place in the body, systemic toxicity will be reduced.

“It looks very promising with mice, rabbits and rats,” Mr. Buxton says. “We are about to fund an initiative to carry it forward to humans.”

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