Production of narrow but deep lesions suitable for ablation of atrial fibrillation using a saline‐cooled narrow beam Nd:YAG laser catheter

Abstract

Irrigated Nd:YAG laser can be used to make deep narrow myocardial lesions without crater formation. Laser ablation may be more suitable than radiofrequency ablation for intraoperative or catheter-based cure of atrial fibrillation.

Myocardial electrical conduction block induced by photosensitization reaction in exposed porcine hearts in vivo

“…The temperature increase of the myocardium is rather small with the photosensitization reaction, compared to thermal ablation therapies in which the maximum temperature of the myocardial surface during the ablation is around 80°C 32, 33. The small temperature increase in the photosensitization reaction might be due to the low input power; the input power required to create a myocardial lesion with 2–3 mm in diameter and several millimeter deep may be <1 W for the photosensitization reaction, and is reported to be 10–30 W for laser ablation 7–9, and 20–50 W for radiofrequency ablation 32. The energy consumption used for singlet oxygen generation in the photosensitization reaction with NPe6 is roughly estimated to be 1.9% of the total input energy under the experimental conditions, by considering (i) a molar absorption coefficient of NPe6, (ii) a quantum yield of singlet oxygen generation, and (iii) a NPe6 concentration in myocardium 18, 21.…”

“…However, there are several limitations of radiofrequency ablation including thermal complications (total incidence rate, 4–6%), such as thromboembolism and cardiac tamponade 4–6. Alternative energy sources for cardiac ablation have been developed such as laser ablation, in which the laser energy is absorbed by the myocardium, resulting in temperature rise of tissue 7–9. However, the laser ablation might face the same problem of the thermal complications as radiofrequency ablation.…”

Heart ablation using a planar rectangular high intensity ultrasound transducer and MRI guidance

“…Laser ablation is a promising technology that may have some advantages over other energy sources [14][15][16]. The energy is focused, unaffected by overlying fat, and uses flexible fiber optics to deliver the energy to tissue.…”

Tilted fibre gratings for sideways light delivery

“…Such requirements arise in some types of "keyhole" surgery where intravenous delivery of laser light via optical fibre is needed to treat internal organs. In a proposed treatment of cardiac arrhythmias, for example, laser light of substantial average power, ~20 W, must be directed sideways in a continuous line of 5-10 mm in length from the side of a multimode optical fibre introduced inside the heart, in order to cause deep lesions at specific positions in the heart muscle [9].…”