Open-irrigated laser catheter ablation: relationship between the level of energy, myocardial thickness, and collateral damages in a dog model

To evaluate laser lesion formation in the beating hearts of dogs by using an open-irrigated electrode-laser mapping and ablation heart catheter.

A total of 50 laser applications at 15 W (n = 31) and 20 W (n = 19) for 10–50 s, with an irrigation flow of 35 mL/min were aimed at the right (n = 15) and left (n = 9) atrial, right (n = 15) and left (n = 11) ventricular walls in five dogs (6–16/dog), by using an open-irrigated laser ablation catheter. The 1064 nm diode laser was provided with a light control system, a Flowmeter, and a transoesophageal laser sensor. Lesions were measured and were evaluated morphometrically. Transmural lesions were achieved in seconds regardless of the level of energy applied. Laser applications at 15 W > 10 s aimed at the atrial walls produced collateral lesions to the lung or to the oesophagus. Laser applications at 20 W > 30 s aimed at the ventricular walls may result in steam pop with intramural cavitations and arrhythmias. Collateral damages to the oesophagus occurred only when the transoesophageal light sensor was deactivated.

To avoid unwanted effects during laser catheter ablation by using an open-irrigated laser catheter energy delivery must be adapted to the thickness of the myocardial wall. Light control system and a transoesophageal light sensor may help reduce the risks of myocardial and collateral damages.