In December, the new device earned approval from the U.S. Food and Drug Administration. Stanford Hospital is one of the few California hospitals now offering it for the treatment of paroxysmal atrial fibrillation that does not respond to drug therapy. It is the first catheter in the United States specifically designed and approved for treating this disease. Its freezing technology was invented by Wang and two other medical scientists in the late 1980s. Wang is now a consultant for Medtronic.
Atrial fibrillation affects some 2.2 million Americans. Risk factors include old age, high blood pressure, sleep apnea and heart disease. The problem stems from chaotic electrical impulses in the upper chambers—the atria—of the heart. A normal heart contraction begins with an electrical signal from the sinoatrial node, a group of cells in the right atrium. In atrial fibrillation, however, signals are sent from other parts of the atria, disrupting the regular cardiac rhythm. These abnormal signals tend to originate where the pulmonary veins empty into the left atrium.
If you observe the heart when the disease is acting up, it looks like a quivering bowl of Jell-O. Symptoms can be subtle and painless, as they were in Tsuji's case, or include shortness of breath, fatigue, lightheadedness and chest pain. In any case, the condition can lead to serious complications: The chaotic rhythm may cause blood to pool in the atria, forming clots. If a clot dislodges, it may travel to the brain and block a blood vessel, causing a stroke. Untreated paroxysmal atrial fibrillation can become chronic, resulting in persistent heartbeat irregularities.
"A-fib tends to aggravate itself, meaning the longer you remain in it, the harder it is to get rid of it," Wang said.
There are several common ways to treat the disease: For patients with the persistent form, in which the rhythm does not go back to normal by itself, doctors can administer an electrical shock to the heart (cardioversion), which resets the rhythm. Medication can also be prescribed to help maintain a normal heartbeat, but many patients do not respond to drug therapy. This was Tsuji's experience and why he was allowed to participate in the clinical trial. Another option is radiofrequency catheter ablation, which heats and kills the tissue responsible for sending out the erratic impulses.