Laser Catheter Modulation of the Sinus Node in the Treatment of Inappropriate Sinus Tachycardia: Experimental and Clinical Results

Abstract

Inappropriate sinus tachycardia (IST) is a rare type of arrhythmia that is currently difficult to treat successfully. The effects of laser catheter applications aimed at the sinus nodal area were tested experimentally and the technique was used for the treatment of IST. Continuous-wave, mapping-guided 1,064 nm neodymium-doped yttrium aluminum garnet laser applications at 15 W (9.5 W/mm 2) per 15 seconds (142.5 J/mm 2) and an irrigation flow of 30 mL/min were aimed at the sinus nodal area in five dogs (three applications each) and one human patient (two applications) by use of an 8-French open-irrigated electrode-laser mapping and ablation (ELMA) catheter provided with three miniature pin electrodes (0.5 mm × 4.0 mm) with interelectrode distances of 2.0 mm arranged symmetrically and radially around the endhole of the catheter tip. Laser application was aimed at the largest and earliest atrial potentials recorded in the focused local electrograms 30 ms to 45 ms prior to the onset of the P-wave in the surface lead electrocardiogram. Lesions were evaluated morphometrically. Holter monitoring in the patient was performed prior to and after treatment. During laser application in the dogs, sinus nodal potential amplitudes dwindled gradually from a mean of 42 mm ± 24 mm to 5.0 mm ± 3.0 mm and sinus cycle lengths lengthened from 452 ms ± 35 ms to 634 ms ± 35 ms (p < 0.0001 for both). In the patient, electrical potential amplitudes in the local electrograms dwindled from 41.0 mm to 5.0 mm and, in the Holter monitor, heart rate decreased from 109 bpm ± 29 bpm to 79 bpm ± 26 bpm (p < 0.0001). IST ablation was painless and without complications. During a follow-up of 4.9 years, the patient was asymptomatic and her heart rate and chronotropic competence remained normal. In conclusion, ablation of IST was achieved by substrate mapping-guided laser application while using the open-irrigated EMLA catheter RytmoLas (LasCor GmbH-Laser Medical Devices, Taufkirchen, Germany). However, this is a proof-of-concept study and further research, preferably in the form of multicenter study trials, is needed for confirmation of the results.

Laser Modification of Sinus Node Function in Dogs

“…We would like to raise awareness about an experimental study we performed almost three decades ago, in which we too employed continuous-wave Nd:YAG laser irradiation for the modification of sinus node function in dogs. 2 There were distinct differences, however, between the study by Weber et al 1 and our study. 2 First, we employed an epicardial rather than endocardial approach.…”

“…I and my colleagues read with great interest the article by Weber et al, 1 in which the authors presented the results of laser catheter modulation of the sinus node under experimental conditions and in a patient with inappropriate sinus tachycardia. 1 In their study, continuous-wave endocardial neodymium-yttrium-aluminum garnet (Nd:YAG) laser applications were delivered to sites showing the largest and earliest atrial potentials in the vicinity of the sinoatrial node. In the canine experiments, weekly electrocardiograms performed for three months showed permanent reduced heart rates.…”

“…Our approach utilized the unique functional anatomy of the sinus node region, showing both a subepicardial location as well as widespread distribution and rate differentiation of the pacemaker complex, with predictable shifts occurring in the sites of impulse formation with changes in the autonomic tone and with certain pharmacologic interventions. 3 Clinical studies are needed to determine whether the endocardial and substrate-based method employed by Weber et al 1 or our epicardial approach of selective, graded ablation of sinus node areas responsible for fast heart rates only is more effective for the control of inappropriate sinus tachycardia.…”

Use of Light Sensor and Focused Local Atrial Electrogram Recordings for the Monitoring of Thermal Injury to the Esophagus and Lungs During Laser Catheter Ablation of the Posterior Atrial Walls: Preclinical In Vitro Porcine and In Vivo Canine Experimental Studies

“…Acute transmural atrial laser lesions of coagulation necrosis, once achieved, will result in a chronic scar that will be permanently devoid of electrical activity. 17,[21][22][23] The SLLS together with online control of electrical potential amplitudes in the focused LEG during laser application may help to protect all of the mediastinal structures from thermal injury and may substantially contribute to the safety and efficacy of the ablation procedure. The SLLS prevents further increase of the mediastinal temperature when overheating is imminent, prior to the occurrence of thermal damage to the esophagus.…”

Inappropriate Sinus Tachycardia: Current Challenges and Future Directions

“…In this issue of The Journal of Innovations in Cardiac Rhythm Management, a potential new treatment option for IST is described. 1 We took this opportunity to review the SA node anatomy and function in relation to what is currently known about IST and considered the limitations of current treatment modalities to highlight the potential role of the new treatment presented. We summarize prognostic data and existing treatment options so that we can clearly counsel our patients with IST to help alleviate their anxiety regarding issues such as left ventricular dysfunction and increased mortality and make them aware of the methods, albeit limited in number, that are available to help manage their symptoms so that they can lead normal lives.…”