Atrial fibrillation (AF) is the most common sustained cardiac rhythm disturbance, increasing in prevalence with age. AF is often associated with structural heart disease, although a substantial proportion of patients with AF have no detectable heart disease. Hemodynamic impairment and thromboembolic events related to AF result in significant morbidity, mortality, and cost. Catheter ablation therapy is widely recognized as a useful modality for patients with fibrillation that are refractory to medical and ICD treatment, and is increasingly used earlier in treatment.
Physicians specializing in Interventional Cardiology (IC) and/or Electrophysiology (EP) are often confronted by the need to precisely place and control a variety of therapeutic and non-therapeutic catheters in the cardiovascular space. A variety of shapeable and steerable sheaths and guide catheters have been developed to meet this need. These manually controlled catheters traditionally rely upon the ability of the experienced physician to apply varying amounts of curvature via pull wires of a steerable catheter. This tip curvature is then used in combination with insertion and torque to manipulate the distal tip of the catheter in a desired fashion. The manual control over the fine movements of the catheter's distal tip typically has limitations for performing complex mapping, ablation and other therapeutic procedures. Maintaining stable tissue contact at the point of ablation is important in achieving efficient heat transfer to tissues without increasing the power requirement, but micro-movement can be difficult to assess. Therefore, stable tissue contact relies on operator skill to exert forces at cardiac tissue that is constantly shifting due to cardio-respiratory movement. Robotic catheter manipulation may be one way to overcome or improve the problem of catheter stability.
In minimally invasive surgery, robotic assisted control of the surgical instruments has helped physicians perform difficult dexterous surgical tasks safely and efficaciously. Robotic remote control of catheters has recently been introduced to assist physicians in the safe, accurate placement of the distal catheter tip during percutaneous cardiac procedures. In ablative procedures it is not known whether improving catheter tip stability has a significant effect on lesion quality compared to the manual approach, but some recent publications of both animal and human studies comparing the Hansen Sensei Robotic System and Artisan guide catheter to manual delivery of the ablation catheter suggest that contact pressure conferred by the robotic system results in improved lesion delivery compared to a manual approach and that the use of robotic manipulation during ablation procedures has a event rate similar to manual manipulation. It has been convention to deliver energy for up to sixty seconds for slow pathway modification and accessory pathways to produce irreversible tissue necrosis. One study suggested that by 30 seconds, robotic ablation appears to exceed the manual ablation signal attenuation at 60 seconds. The study confirmed that transmural lesions were produced at 30 seconds of robotic ablation. Therefore, it may be possible to use shorter ablation times or lower power settings for robotic approaches. This may in turn reduce the likelihood of complications for example, the risk of damage to contiguous structures and the risk of steam pop which is most likely to occur after 30s at temperatures greater than 400C.
Subjects who satisfy the inclusion and exclusion criteria shall be randomized 2:1 between the robotic arm and the manual control arm of the trial. Those in the manual control arm will receive treatment for their arrhythmia per the investigators standard practice and the labeling for the Navistar ThermoCool. Subjects in the robotic arm will be treated according to the following parameters:
- Place ablative lesions 1-2 cm outside of the pulmonary veins in order to minimize the risk of pulmonary vein stenosis.
- Target IntelliSense readings of 10-20g, with a maximum of 40g, during lesion creation.
- Target lesion creation at RF power settings of 20-25W with a nominal maximum power of 30W. Starting at 20-25W in an anatomical region, RF power may be increased after 15 seconds in 5W increments to achieve a transmural lesion as shown by local atrial electrogram attenuation or splitting. Ablation duration at a single anatomical lesion location is recommended to be no longer than 30 seconds. If ablation output time for the RF generator is set for longer than 30 seconds, the ablation catheter should be moved so that the ablation catheter duration in a particular location doesn't exceed 30 seconds. Remember that stable contact between the catheter tip and the tissue increases the efficiency of RF power transfer to the tissue.
- For power levels up to 30W, a flow rate of 17 ml/min should be used.
- If the temperature increases to greater than 50°C or the impedance rises 20Ω or more, the RF application should be terminated immediately, the catheter removed and the coagulum removed (if present), and irrigation flow confirmed before the catheter is used again.
After the index procedure, subjects will receive follow-up monitoring as follows:
7 Day: A phone call will be made to the subject to inquire regarding any adverse events and to assess any change in NYHA classification since discharge.
30 day: Subjects will be asked to return for a follow-up visit at 30 days. At this follow-up visit, subjects will undergo an evaluation for changes in medications (anti-arrhythmic, anti-platelet or anti-coagulation) and adverse events, and receive a physical examination and 12L EKG.
90 day:Subjects will be asked to return for a follow-up visit at 90 days. At this follow-up visit, subjects will undergo the same evaluation as at 30 days. An event recorder issued to patient at this visit to be used through day 365 (1 year) to document symptomatic recurrence of AF.
180 day: Subjects will be asked to return for a follow-up visit at 180 days. At this follow-up visit, subjects will undergo the same evaluation as at 30 days. In addition a 24 hour Holter monitor recording and a Cardiac CT or MR will be obtained.
365 day: Subjects will be asked to return for a follow-up visit at 365. At this follow-up visit, subjects will undergo the same evaluation as at 30 days. In addition a 24 hour Holter monitor recording and a potentially a Cardiac CT or MR will be obtained.
1. Patients with paroxysmal atrial fibrillation who have had two or more spontaneously terminating episodes of atrial fibrillation, that last longer than 30 seconds and shorter than 7 days, in the nine months prior to enrollment. At least one episode must be documented with EKG, TTM, Holter monitor, or telemetry.
2. Failure of at least one Class I - IV anti-arrhythmic drug (AAD) for PAF as evidenced by recurrent symptomatic PAF, or intolerable side effects due to AAD. AADs are defined in Appendix B.
3. Signed informed consent.
4. Age 18 years or older
5. Able and willing to comply with all pre-, post-, and follow-up testing and requirements.
1. Atrial fibrillation secondary to electrolyte imbalance, thyroid disease, or reversible or non-cardiac cause.
2. Previous ablation for atrial fibrillation.
3. Atrial fibrillation episodes that last less than 7 days and are terminated by cardioversion.
4. Previous valvular cardiac surgery procedure.
5. Cardiac artery bypass graft procedure within the previous 180 days.
6. Previous septal defect repair.
7. Expecting cardiac transplantation or other cardiac surgery within the next 180 days.
8. Coronary PTCA/stenting within the previous 180 days.
9. Documented left atrial thrombus on ultrasound imaging (TEE).
10. Documented history of a thrombo-embolic event within the previous year.
11. Diagnosed atrial myxoma.
12. Presence of an implanted ICD.
13. Presence of permanent pacing leads.
14. Significant restrictive, constrictive, or chronic obstructive pulmonary disease or any other disease or malfunction of the lungs or respiratory system with chronic symptoms.
15. Significant congenital anomaly or medical problem that in the opinion of the investigator would preclude enrollment in this study.
16. Women who are pregnant.
17. Acute illness or active infection at time of index procedure documented by either pain, fever, drainage, positive culture and/or leukocytosis (WBC > 11.000 mm3) for which antibiotics have been or will be prescribed.
18. Creatinine > 2.5 mg/dl (or > 221 µmol/L).
19. Unstable angina.
20. Myocardial infarction within the previous 60 days.
21. Left ventricular ejection fraction less than 40%
22. History of blood clotting or bleeding abnormalities.
23. Contraindication to anticoagulation.
24. Contraindication to computed tomography or magnetic resonance imaging procedures.
25. Life expectancy less than 1 year.
26. Enrollment in another investigational study.
27. Uncontrolled heart failure (NYHA class III or IV heart failure).
28. Presence of an intramural thrombus, tumor, or other abnormality that precludes catheter introduction or positioning.
29. Presence of a condition that precludes vascular access.
30. Left Atrial size ≥ 50mm.
31. INR greater than 3.0 within 24 hours of procedure.
Last updated: 08/22/2012