Thermoplasty: A New Treatment for Resistant Asthmaby Eli Hendel, M.D. Medical Reviewer
Asthma Can Be Treated
Asthma is usually a reversible disease. By that I mean that whether it’s caused by spasm of the airways or thickening of the inner mucosal layer (due to inflammation), once treated, the airway reverts to its normal anatomy and there are no permanent changes (unlike COPD). When a patient is diagnosed as a severe asthmatic, the clinician is referring to the number of attacks or exacerbations, but even in that scenario, ultimately all patients should have normal bronchial anatomy, once treated.
National guidelines have been devised to help achieve consistency in treatment and utilization of specific and appropriate treatments in asthma. These guidelines are called The National Asthma Education and Prevention Program Expert Panel Report, or NAEPP. It sets the stepwise approach for adding medications to the treatment regimen, based on the measurable symptoms present. All doctors who treat asthma should be familiar with this stepwise framework.
Understanding Resistant Asthma
There are, however, a number of people who suffer with asthma, that in spite of receiving appropriate treatment, do not respond well. Their diagnosis would then be classified as resistant asthma and they experience persistent narrowing of the airways (and symptoms). These patients run the risk of having permanent changes in the anatomy of their airways which will cause permanent narrowing. This happens due to the thickening of the muscle layer in the airways that cause the airway spasms, resulting in asthma. In this specific instance, the change is permanent. This is a process that is known as “remodeling.” When remodeling occurs, standard medications will not work. What can modern medicine do to help these patients?
Treating Resistant Asthma
A new technology has been developed called thermoplasty. It consists of introducing radiofrequency energy to the airway wall, which heats the tissue and reduces the amount of muscle, literally thinning it out. The technology is not quite so new, having been used regularly as ablation treatment for cardiac arrhythmias like atrial fibrillation, and also in lung cancer.
The specialist performs a bronchoscopy, using a fiber-optic instrument that is introduced through the nasal passage of the nose into the lung airways. For 10 seconds, specific temperature-controlled bursts of radio frequency energy heat the lining of the lungs. Other tissues in the surrounding area are also destroyed as well, but it is specifically the muscle cells that do not have the ability to regenerate. So, by reducing the amount of muscle cells with this technique, you reduce the chance of contraction of the airways that induce the spasm, and the asthma attacks.
Ideal Candidates for Thermoplasty
The selection of ideal candidates for this procedure is not clear-cut. On one hand, they are the asthmatics who cannot be controlled with medications. On the other hand, they should not have hyper-reactive airways at the time of the procedure, since they may react adversely to the heat administered. These patients must not have had a severe exacerbation of asthma in the previous four weeks prior to thermoplasty. They should not have an implantable electronic device, such as a cardiac pacemaker, and they should not have co-morbid conditions, such as those associated with morbid obesity.
Thermoplasty cannot be taken lightly. It is a serious procedure when your target is to destroy muscle cells (which will not regenerate). The candidates for the procedure must be carefully selected. Maybe that’s why the recent literature has shown good results and relatively few adverse events. I personally think that being highly selective is a prudent approach as I reflect on other procedures that use radiofrequency that were done more liberally in the past and resulted in negative outcomes. Thermoplasty does give hope to a group of asthma patients who need an alternative to the traditional medications.