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New device at Overlake Hospital helps cure atrial fibrillation | With good technique surgeons have an 80- to 90-percent rate of non-recurrence in patients
Overlake Hospital Medical Center's electrophysiology program is using new pressure feedback technology to increase success in a procedure to cure atrial fibrillation.
Dr. Derek Rodrigues says to think of atrial fibrillation — Afib — like an electrical storm in the heart. And, in a sense, it is. To understand what's happening, you have to understand the layout of the organ at the center of the circulatory system. There are four chambers: two atria and two ventricles, working together as the human body's blood pump.
"But I like to think of the heart as two pumps joined together," says Rodrigues, a cardiologist and the founder of Overlake Hospital's electrophysiology program. "There's a left pump and a right pump. The way the circulatory system works, blood enters into the right side atrium, then travels into the right ventricle. The ventricle pumps blood out of the heart to the lungs where it becomes oxygenated, and back to the left side of the heart into the atrium, through the pulmonary veins."
The movement of blood is made possible by the electrical system prompting the heart to contract into beats, at a rate of 60 to 100 per minute. These signals originate in a cluster of cells known as the sinus node. The electrical impulse prompts the atria to beat, then moves to another group of cells known as the atrioventricular node, which relays the signal to the ventricles to beat.
That's what occurs in a healthy heart. But in a heart suffering from atrial fibrillation, the most common heart arrhythmia, irregular electrical signals are produced elsewhere in the heart, creating a fast or irregular heartbeat. Though some Afib patients don't show symptoms, the condition can debilitate others with dizziness and shortness of breath. Symptoms are more likely to show as patients grow older.
Electrical signals from the pulmonary veins were pinpointed as the source of atrial fibrillation by the team of doctor Michel Haïssaguerre in the 1990s.
Haïssaguerre pioneered the technique of isolating signals from the pulmonary veins to cure Afib. Afib ablation is now commonly achieved surgically by a catheter device snaked up an artery in the leg. After mapping the interior of the heart, the surgeon will use radiofrequency to create lesions around the pulmonary vein, creating a barrier to unwanted electrical signals. The procedure is minimally invasive and provides an alternative to the open-heart "maze" procedure.
Rodrigues estimates that, exercising good technique, surgeons with Overlake had been able to achieve an 80- to 90 percent rate of non-recurrence in patients — the fibrillation was cured and symptoms did not reappear.
So what about the remainder? Proper ablation requires surgeons to hit a sweet spot in terms of the pressure the tip of the catheter puts on the walls of the heart. Too little and lesions wouldn't form effectively. Too much and the tissue could be perforated.
The problem with the ablation procedure as it was being accomplished previously, was that it had to be done somewhat blind in terms of pressure. And surgeons erring on the side of caution would, 10- to 20-percent of the time, apply too little pressure to complete the scarring.
"Because you're applying pressure on this end of the tool, but you're operating it all the way from the other end, it's not easy to feel the pressure being made," Rodrigues says.
Today, Overlake is the first hospital to use the ThermoCool SmartTouch, a catheter that provides computer feedback to the amount of pressure being applied during ablation procedures.
An additional benefit of the new catheter is the ability to create 3D maps of the interior of the heart, verified and completed by ultrasound. The mapping process has been cut by more than half using the new tech.
Atrial fibrillation affects more than 2.5 million American adults. As many as 12 million people in the country will have the condition by 2050, according to the American Heart Association.
Catheter provides computer feedback to the amount of pressure being applied during ablation procedures. Below: catheter also provides 3D maps of the interior of the heart, verified and completed by ultrasound. COURTESY PHOTOS