Atrial fibrillation (AF) is the most common cardiac arrhythmia in the United States today. Its incidence increases with age, and the prevalence approaches 10% in patients over 80 years old. Atrial fibrillation increases the risk of strokes, and in some patients is associated with worsened congestive heart failure and quality of life.
Catheter based radiofrequency ablation for atrial fibrillation is an evolving and promising technology, and provides increased freedom from AF and improved quality of life compared with pharmacologic therapy. The technique involves placing catheters through the femoral veins into the heart, including the left atrium. Access to the left atrium is performed by transseptal puncture. Ablation of atrial fibrillation is performed by delivery of radiofrequency energy around the pulmonary veins in order to electrically dissociate them from the atria. This is thought to eliminate common triggers for atrial fibrillation, and therefore reduces the recurrence of AF in some patients.
The ablation procedure is done under general anesthesia and takes 4-8 hours. The first part of the procedure involves creating a computer generated three dimensional model of the left atrium. Once this model is created any patient movement will disrupt its accuracy and interfere with the physician's ability to accurately locate the catheter within the atrium.
The success of AF ablation is dependent upon the creation of an accurate three dimensional model, as well as physicians ability to perform durable lesions and achieve effective isolation of the pulmonary veins. Among the barriers to technical success are the patient's respiratory movement, which impairs catheter stability and the ability to maintain a stable catheter position against the atrium of the heart during ablation. Thus, minimizing respiratory movement during the procedure is critical to procedural outcome.
High frequency jet ventilation (HFJV) is a newer mode of ventilation that relies on very small tidal volumes delivered at high frequency (approximately 80-120 breaths/minute). Initially developed in the critical care setting, HFJV produces less respiratory motion due the small tidal volumes delivered. HFJV has been used successfully in procedures requiring increased stability of the field of interest, such as lithotripsy and percutaneous hepatic and renal radiofrequency ablation as well as stereotactic high single-dose irradiation of stage I non-small cell lung cancer and lung metastases. The initial report of the use of HFJV in radiofrequency catheter ablation (RFCA) of atrial fibrillation was by Goode et al in 2006. In that retrospective analysis, the use of HFJV was associated with a decrease in the number of ablation lesions, due to decreased number of attempts aborted by catheter dislodgement, as well as decreased variation in the size of the left atrium (LA) due to changes in pulmonary pressures associated with conventional ventilation. The incidence of complications was not significantly different between the HFJV and conventionally ventilated patients. More recently, Elkassabany et al. retrospectively reviewed their institutional experience with Jet ventilation, and found that the procedure could be performed safely.
HFJV is increasingly used and may improve procedure efficacy and safety, and may be cost effective. Data however are limited to small series and retrospective reviews. In order to better compare the efficacy and safety of HFJV to conventional ventilation, the investigators propose to conduct a prospective randomized study comparing the use of HJFV and conventional ventilation in patients undergoing pulmonary vein isolation (PVI) at our institution. Our hypothesis is that HFJV, by allowing greater catheter stability and more accurate mapping of the left atrium will allow more effective radiofrequency lesion creation, leading to a quicker procedure, requiring fewer lesions and less ablation and fluoroscopy time with more effective isolation of the pulmonary veins with better short and long term control of AF.
