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
"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.