Atrial Fibrillation

Atrial fibrillation (AF), the most common cardiac arrhythmia, is estimated to affect five million patients in the U.S. and 30 million globally. Atrial fibrillation is the rapid and uncontrolled beating of the atria, the upper chambers of the heart. Irregular signals from the pulmonary veins are a source of AF, particularly in the disorder’s early stages. Atrial fibrillation is associated with other disorders such as congestive heart failure, myocardial infarction, valve disease, hypertension, infection and sleep apnea. Patients with AF can have palpitations, chest discomfort, weakness, fainting, breathlessness and sometimes, no symptoms at all. The burden of AF can significantly affect the quality of life for these patients by limiting their ability to work and play.

A current treatment for atrial fibrillation is called ablation. One ablation method uses radio-frequency (RF) energy to burn and destroy the tissue around the pulmonary veins to isolate the irregular signals causing AF. There are many limitations to current RF ablation procedures for AF. On average, only 60% of the current 150,000 ablations performed for AF in the US annually are effective. Thirty percent of the cases are repeated one or two additional times due to recurring AF, resulting in patient discomfort and increased costs.  Why is this occurring?

There are several limitations that contribute to unsuccessful ablation treatments.

Poor ablator-tissue contact
Gaps or inflammation in the ablated tissue, may allow electrical signals to leak passed the lesion. This may contribute to the recurrence of AF during the ablation procedure or even months later. Anatomical variation of the pulmonary veins observed in many patients can be a cause of poor ablator-tissue contact as well, also contributing to recurrence.

Difficulties performing ablation with current technology
Often taking between four and eight hours, catheter ablation procedures are tedious and difficult to perform because the heart is beating during the procedure, making it difficult to place and hold the electrode at the precise location for the duration of the ablation cycle.  Also, because the physician has to locate and navigate the catheter to multiple discrete positions within the tight confines of the heart’s left atrium, fluoroscopy is often used for extended periods. This presents a hazard to clinical staff and patients exposed to radiation emitted by the fluoroscope.

Long learning curve for physicians performing ablation procedures
The learning curve for physicians to develop the skills for successful ablation with current ablation catheters is as many as 25 to 50 cases.

Poor economics
Physicians and hospitals are reimbursed for ablations regardless of the amount of time it takes or the resources required to completing them.

In order to treat many untreated and under-treated patients, electrophysiologists (EPs) are looking for ablation catheters that will make procedures easier-to-perform, provide continuous ablator-tissue contact and result in effective and reliable patient outcome the first time. The challenge for clinicians is to provide safe and effective procedures in which durable lesions are created reliably.

For more information
Video presentations on Atrial Fibrillation and Atrial Fibrillation Ablation are presented by at their site.

   “Stroke Severity in Atrial fibrillation”; The Framingham Study, AHA, 1996.
   “Atrial fibrillation is associated with severe acute ischemic stroke.”; Neuroepidemiology. Mar-Apr 2003; 22(2):118-23.
   Leerink Swann; “Medical Devices – Cardiology”, 13 Sep 2013.
HJGM Crijns, et al. “Why is atrial fibrillation bad for you?” from Nonpharmacological Management of Atrial Fibrillation 1997

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