Mechanical hyperventilation could streamline cardiac ablation

A medical technique that involves safely hyperventilating conscious, unmedicated patients could facilitate the use of radiotherapy for cardiac ablation, according to research published in Frontiers in Physiology

The technique, called mechanical hyperventilation, was first proposed by Michael J. Parkes, MA, DPhil, and colleagues as a means for diagnosing ischemic heart disease earlier. The team was looking to explore whether the effect of hyperventilation on vascular function—hypocapnia which leads to a temporary constriction in the coronary arteries—could function as an early red flag for CVD.

Mechanical hyperventilation involves a mechanical ventilator that delivers air to a patient via a face mask. Parkes et al. found during the course of their research that both the technique and hypocapnia were well-tolerated in patients with angina, suggesting physicians could safely induce breath-holds of over five minutes.

Those prolonged periods of stillness could be particularly useful in supporting radiotherapy, the authors said, an emerging technique that offers an alternative to radiofrequency or freezing for cardiac ablation. When a patient with an arrhythmia undergoes ablation, targeted radiotherapy is delivered from outside the chest to destroy tissue that might be causing that patient’s abnormalities. Breathing during the process is an issue because, with each breath, the patient’s heart moves within their chest.

“Stopping breathing with a safe breath-hold of over five minutes, using mechanically induced hypocapnia and now with oxygen-enriched air, could allow surgeons to target the radiotherapy for cardiac ablation much more precisely,” Parkes, of the University of Birmingham in the U.K., said in a release. “The advantage of radiotherapy over radiofrequency or freezing is that radiotherapy is completely noninvasive and is applied from outside the chest.”

Radiofrequency and freezing require a catheter, he said, which is passed through a vein in the groin or an artery in the neck to reach the atria. Right now, radiotherapy is only considered when all other ablation techniques have failed.

“There is still little awareness of the simplicity, availability and safety of noninvasive mechanical hyperventilation,” he said. “We have already shown that patients with breast cancer can breath-hold safely for over five minutes using this technique. The fact that patients with angina were able to tolerate mechanical hyperventilation so well confirms its potential to improve the newly emerging procedure or using radiotherapy for cardiac ablation.”

Parkes said his team’s next step is to test the approach in patients with cardiac arrhythmias.

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