Doctor’s Orders: TAVR catheter system revolutionizing heart procedure

“Every once in a while, a new technology, an old problem, and a big idea turn into an innovation” — Dean Kamen (renaissance man, inventor of the Segway and the insulin pump)

The fields of artificial intelligence, computer science, machine learning, cryptography and robotics are frantically trying to discover new ways to answer old problems. Or better yet, to create completely new paradigms of science and technology.

One old problem that medicine and surgery have been trying to tackle has been heart disease. The 20th century witnessed an explosion in our ability to diagnose and treat various heart ailments.

Thousands of coronary angiograms are performed in the United States each year. This is the procedure in which a catheter is inserted into a patient’s leg or wrist and guided under x-ray technology to the patient’s heart arteries. A contrast dye is safely injected to the heart arteries and pictures are taken in order to determine whether or not there are blockages.

There is an interesting story about the first catheterization performed on a living human being: A German physician named Werner Forssmann inserted a catheter into himself! He then walked to the x-ray department and took his own x-rays. In 1956, Dr. Forssmann later shared the Nobel Prize with Andre Cournand and Dickinson Richards for “discoveries concerning heart catheterization and pathological changes in the circulatory system.”

In the 1970s, another breakthrough was done by a Swiss physician, Dr. Andreas Gruentzig, who performed the first coronary angioplasty on a human. An angioplasty is a technique that involves inserting a catheter with a small inflatable balloon to open heart artery blockages.

This technology has grown exponentially and now most patients now receive a permanent stent across a blockage.

One of the benefits that occurred with these catheter-based interventions was the reduction in coronary bypass or open-heart operations. The catheter-based interventions reduce hospital stays and recovery time as well as procedure time. And, there is no need for the heart-lung machine in a catheter-based procedure.

Because of the success of coronary interventions, cardiologists began to explore other uses for this technology.

Balloons have been successfully used to open up tight mitral valves. However, after some initial optimism about using balloons to open up tight aortic valves, the high complication rate all but killed the use of balloon “valvuloplasty” for aortic valve stenosis or tightness.

Aortic stenosis or tightness remains a serious problem and thousands of open-heart operations are performed every year to implant artificial heart valves, especially in the elderly. These operations can take several hours to perform and require prolonged hospitalization and rehabilitation stays.

One wonderful new catheter-based system is now available to tackle the problem of aortic stenosis. It is called transcatheter aortic valve replacement or TAVR for short. Dr. Alain Cribier of France who had first used a balloon catheter to treat tight aortic valves in the elderly, did not get discouraged by the disappointing result with the balloon. He developed a stent-based valve that could be inserted into the heart without opening the chest.

In this procedure, a catheter is inserted into the patient’s leg artery and guided to the patient’s heart. The collapsed new valve that is inserted through the catheter is expanded across the patient’s tight valve. The new valve in a sense “pushes the old valve out of the way”.

This new replacement valve will remain permanently in the correct position. This procedure takes about two hours and patients routinely go home in two to three days.

Right now, only a specified subgroup of patients is eligible for the TAVR procedure. I suspect that as our experience with this procedure grows so will its use.

Oh, Brave New World!

Dr. Alan Jackson is an assistant professor of medicine at Rush University. He is also a member of the board of directors of the Chicago Sun-Times.