The catheter system, which is being commercialized by CryoCor of San Diego, Calif., is designed to selectively freeze cardiac tissue in order to block the abnormal electrical signals that cause arrhythmia, thereby returning the heart to its normal rhythm. On June 29 the company announced Food and Drug Administration (FDA) approval for clinical trials to evaluate the system's safety and efficacy in treating atrial fibrillation, an irregular heart rhythm that affects about 2.3 million Americans and increases the risk of stroke and death. Clinical trials are already under way to treat atrial flutter, or rapid heart rate.
International clinical trials had a 98 percent overall treatment success rate, and the company has approval to sell the system in Europe. The technology offers a potential cure for arrhythmia, whereas current treatments, including drug therapy and implantable devices such as pacemakers, are management strategies.
The system consists of a catheter about 3 mm in diameter, a sheath for introducing the catheter into pulmonary veins, and a console for controlling the temperature of refrigerant inside the catheter and thus the size of the tissue area to be frozen. Inside the heart, the catheter can achieve temperatures below minus 80 degrees Celsius (minus 112 degrees Fahrenheit).
CryoCor is a spin-off of CryoGen Inc. of San Diego, Calif., which originally worked with NIST researchers through a cooperative research and development agreement to develop the ultracold catheter. CryoGen has used some of the same technology to develop a way to treat abnormal uterine bleeding. Approved for clinical use in 2001, the procedure is an alternative to a hysterectomy and has a one-day recovery period instead of up to 6 weeks. CryoGen was purchased by American Medical Systems in 2002.