Bronchial thermoplasty reduces asthma symptoms

Earlier this year the US Food and Drug Administration approved the first medical device that uses heat to treat severe asthma. This treatment, known as "bronchial thermoplasty", is designed to prevent the airway constriction that is a hallmark of asthma by eliminating some of the smooth muscle that surrounds the breathing passages.

When irritated or inflamed, this airway smooth muscle contracts, narrowing the breathing passages. This causes wheezing and reduced breathing capacity that can be severe and even life threatening.

Performed as an outpatient procedure, physicians insert a thin flexible tube through the nose or mouth, down the throat and into the major airways of the lungs. Then they pass a narrow catheter, with a small expandable heat source at the tip, through that tube.

"This is an entirely novel and quite exciting approach to treating asthma, unlike anything else available," said pulmonologist Kyle Hogarth, MD, assistant professor of medicine and medical director of the Pulmonary Rehabilitation Program.

The smooth muscle that lines the human airway "is a lot like the appendix, it serves no known purpose," Hogarth said, "other than to cause serious medical problems." There is no disease or deficit caused by the loss of airway smooth muscle.

In people with asthma, however, this vestigial tissue can become hypersensitive and contracts when irritated. Fortunately, smooth muscle is uniquely heat sensitive. It can be eliminated without lasting damage to the epithelial cell layers that line the inner surface of the airways. After thermoplasty, epithelial re-growth is quick and complete. The smooth muscle at the treatment site is replaced by loose connective tissue.

The FDA based its approval on data from a clinical trial of 297 patients. The trial showed a reduction of severe asthma attacks after treatment. The University of Chicago Medical Center was one of about 30 centers around the world, and the only one in Illinois, that participated in the Asthma Interventional Research 2 (AIR2) clinical trial.

The Bronchial Thermoplasty System is intended for patients 18 and older whose severe and persistent asthma is not well-controlled with inhaled corticosteroids and long-acting beta-agonist medications.

(Source: University of Chicago)