High Frequency Jet Ventilation in AF Ablation

Atrial fibrillation (AF) is a cardiac condition that results in patients experiencing an irregular heart beat resulting in symptoms including palpitations and breathlessness. It is known that in most cases, AF is caused by abnormal electrical activity from the top of the left side of the heart (left atrium) which overrides the heart natural pacemaker in the right atrium. Treatment options include tablets which suppress this abnormal electrical activity, but in some patients these are not sufficient and a procedure is carried out where the areas of abnormal electrical activity are disconnected or 'ablated' to prevent AF from occurring. This treatment is well established and performed worldwide, often under general anaesthetic (GA). The heart and lungs sit close together in the chest, and when the lungs are inflated and deflated during the procedure, the heart also moves. This movement is then transmitted to the special wires or 'catheters' that are placed inside the heart to deliver the ablation treatment. Instability during the treatment can result in ineffective areas of ablation which may later contribute to reduced success of the procedure. Previous research has shown that by reducing the movement of the heart under anaesthesia using alternative techniques can improve catheter stability and improve procedural results. Once such technique is called high frequency jet ventilation (HFJV) which allows the lungs to filled with air using fast and shallow breaths resulting in normal blood oxygen levels with little movement in the heart. This technique has been shown to be safe and effective for this procedure but a direct comparison with conventional ventilation has not been done. The investigators wish to test this and determine if using HFJV improves outcomes during the procedure (i.e. can investigators do the treatment faster and more effectively) and if this translates to better outcomes long term.

Study Overview

• Status: Completed
• Conditions: Atrial Fibrillation
• Intervention / Treatment: Device: Conventional ventilation; Device: High frequency jet ventilation

Detailed Description

Catheter ablation for the treatment of the symptoms of fibrillation is now a well-established technique. The technique is complex and commonly undertaken under general anaesthesia. Catheters are introduced into the circulation from the veins at the top of the leg and advanced to the right side of the heart. Using x-ray and ultrasound guidance, the catheters are passed to the left atrium by puncturing the muscle that divides left and right atria (septum). A model of the left atrium is created and this used to guide the movement of an ablation catheter across the tissue and create ablation lesions that lead to electrical isolation of target sites.

Under general anaesthesia, the lungs are inflated and deflated via the ventilator circuit. The expansion of the lungs results in movement of the heart with each respiratory cycle. This leads to catheter instability as the tissue is moved towards and away from a catheter positioned in the left atrium. This movement is particularly marked at the back of the left atrium. This instability can lead to real time variation in the delivery of energy which can result in ineffective lesions. These will then translate acutely to incomplete isolation and the need for further ablation (thereby increasing procedure time) and later into reconnection of tissue which can result in repeated procedures being needed to achieve an effective outcome. Each procedure carries risk of minor and major complications therefore measures to improve first time success are critical.

Current research supports the use of steerable catheter sheaths (tubes through which the catheters travel to the atria) and 3 dimensional mapping in improving ablation parameters. Data also exists demonstrating significant variation in catheter contact despite these measures. In order to improve catheter stability further, changes to the mode of ventilation has been studied. Small studies have shown that by stopping cardiac movement altogether by transiently stopping ventilation (apnoea) catheter stability is improved and ablation is more effective. However, intermittent apnoea is not an effective method of ventilation in long cases. An alternative is high frequency jet ventilation. This is where the lungs are ventilated with low volume, high speed and high pressure breaths. This technique is well established and has safety data in upper airway surgery and liver radiology procedures where movement of airways and diaphragm needs to be minimized. In view of this, this technique has been studied in AF ablation and has been shown to improve catheter stability and energy delivery with no increase in complications related to the mode of ventilation. However, existing studies have focused mainly in paroxysmal AF patients (where less ablation is needed) and conducted in a non randomized trial design.

The investigators wish to research the use of HFJV in patients undergoing ablation for persistent AF in a prospective and randomised trial to answer the primary and secondary questions shown below.

• Study Type: Interventional
• Enrollment (Actual): 30
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United Kingdom
  • Oxfordshire
    • Oxford, Oxfordshire, United Kingdom, OX3 9DU
      • John Radcliffe Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 85 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Participant is willing and able to give informed consent for participation in the study.
• Male or Female, aged 18 years or above.
• Indication for left atrial catheter ablation for persistent atrial fibrillation
• Patients may be enrolled in other atrial fibrillation trials at Oxford University Hospitals Foundation Trust (unless directly related to ventilation or ablation strategy)

Exclusion Criteria:

• Age<18 and >85
• Left ventricular ejection fraction <35%
• Severe lung disease - chronic obstructive pulmonary disease or asthma requiring home oxygen therapy or >3 admissions in preceding 12 months
• Previously failed high frequency jet ventilation due to hypercapnia
• Previous catheter ablation for atrial fibrillation

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Conventional ventilation; Catheter ablation for persistent atrial fibrillation with general anesthesia and conventional ventilation	Device: Conventional ventilation; General anaesthesia and ventilation with a conventional Phillips intermittent positive pressure ventilator system
Experimental: Jet ventilation; Catheter ablation for persistent atrial fibrillation with general anesthesia and high frequency jet ventilation	Device: High frequency jet ventilation; General anaesthesia and ventilation with the Acutronic Monsoon III Jet ventilator system

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of patients with improved catheter contact force during AF ablation under high frequency jet ventilation	Data will be extracted from the St Jude Medical Velocity/Tacticath system to determine average force (grams/sec) for each applied lesion.	12 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of patients with improved lesion power delivery during AF ablation under high frequency jet ventilation	Data will be extracted from the St Jude Medical Velocity/Tacticath system to determine power delivery (force time integral) for each applied lesion.	12 months
Number of patients with improved lesion creation during AF ablation under high frequency jet ventilation	Data will be extracted from the St Jude Medical Velocity/Tacticath system to determine power delivery (lesion size index) for each applied lesion.	12 months
Number of patients with improved catheter stability during AF ablation under high frequency jet ventilation	Data will be extracted from the St Jude Medical Velocity/Tacticath system to determine catheter movement (mm movement during ablation) for each applied lesion.	12 months

Collaborators and Investigators

• Sponsor: Oxford University Hospitals NHS Trust
• Investigators: Study Chair: Yaver Bashir, MA,DM,FRCP, Clinical Director, Consultant Electrophysiologist

Study record dates

Study Major Dates

• Study Start (Actual): April 7, 2017
• Primary Completion (Actual): November 7, 2017
• Study Completion (Actual): May 31, 2019

Study Registration Dates

• First Submitted: February 1, 2016
• First Submitted That Met QC Criteria: November 15, 2016
• First Posted (Estimate): November 18, 2016

Study Record Updates

• Last Update Posted (Actual): June 1, 2021
• Last Update Submitted That Met QC Criteria: May 27, 2021
• Last Verified: November 1, 2016

More Information

Terms related to this study

• Keywords: general anaesthesia; atrial fibrillation; catheter ablation
• Additional Relevant MeSH Terms: Pathologic Processes; Heart Diseases; Cardiovascular Diseases; Arrhythmias, Cardiac; Atrial Fibrillation
• Other Study ID Numbers: PID11559

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No