Jason S. Bradfield, MD, on Epicardial Ablation of Ventricular Tachycardia
Epicardial ablation is needed to eliminate ventricular tachycardia (VT) in some patients. However, there are some risks to patient outcomes. A session presented at the 40th Heart Rhythm Scientific Sessions1 highlighted those risks and explored how to improve success rates.
Co-presenter Jason S. Bradfield, MD, answered our questions about his session. Dr Bradfield is an associate professor of medicine at the David Geffen School of Medicine at UCLA and director of the Specialized Program for Ventricular Tachycardia at the UCLA Cardiac Arrhythmia Center in Los Angeles, California.
CARDIOLOGY CONSULTANT: How can providers minimize risk and improve outcomes of epicardial mapping/ablation?
Jason Bradfield: Minimizing risk for epicardial procedures predominantly involves 2 issues: epicardial access itself and avoiding collateral damage during ablation. The most challenging aspect for physicians is to gain enough experience with percutaneous epicardial access to be able to perform the procedure safely. Given the limited number of high-volume centers, this can be a challenge for trainees. The technique for percutaneous access for epicardial procedures has not changed significantly since described by Eduardo Sosa and colleagues,2 and therefore volume of procedures performed and assisted with is really a key factor for safety.
A detailed understanding of cardiac/thoracic/abdominal anatomy is also essential. Many complications can be avoided by understanding the detailed anatomy of the structures you are trying to access and those you are trying to avoid. Many surgeons have moved to using a micro-puncture needle, which theoretically should result in a smaller puncture if the right ventricle is inadvertently injured during attempted access. Additionally, newer technology is being developed, including pressure sensors and tools to retract the pericardium away from the heart prior to access. These new technologies are meant to decrease risk and allow more physicians to perform the procedure safely. Whether this will be true remains to be seen. Avoiding collateral damage during ablation again really comes down to understanding anatomy. Ensuring ablation is sufficiently distant from coronary arteries and the phrenic nerve is essential
CARDIO CON: What challenges of epicardial ablation of VT do you face? How do you overcome these challenges?
JB: Current radiofrequency ablation technology was not developed for percutaneous epicardial ablation. Radiofrequency catheters were developed for endocardial ablation and can face impedance issues in the pericardial space. Further, it can be a challenge to know whether the ablation catheter is applying pressure on the epicardial surface of the heart or away from the heart against the pericardium itself.
Contact force catheters have been developed and have great utility for endocardial ablation, but in the epicardial space, they have not been validated and the pressure readings have little value. Given the epicardial location of coronary arteries, many essential locations that would benefit from ablation are limited by risk of damage to these arteries. Ultimately, technology that can deliver lesions deep to the coronary and not damage the coronary itself are needed to optimize our ability to successfully ablate epicardial and mid-myocardial substrates.
CARDIO CON: If you could pose a question to your peers what would it be?
JB: How do we do a better job of educating our colleagues in internal medicine and cardiology about ventricular tachycardia ablation and the benefits of early referral and earlier intervention?
CARDIO CON: What is the key take-home message for cardiologists?
JB: Ventricular tachycardia ablation has clear benefit for patients that either fail antiarrhythmic drugs or do not tolerate/prefer not to take antiarrhythmic drugs. VT should be treated in a similar manner to cardiomyopathy. If your patient develops cardiomyopathy, it is always best to have him seen by a cardiomyopathy/transplant physician earlier in his disease course, in case he needs more advanced intervention down the line. Waiting until your patient is in cardiogenic shock in an intensive care unit is suboptimal. Unfortunately, with ventricular tachycardia, centers capable of performing VT ablation, including epicardial ablation, are often not referred patients until patients are critically ill with VT storm and have failed multiple antiarrhythmics. Early referral improves outcomes and can decrease the acute procedural risk.
Epicardial ablation is often required for nonischemic cardiomyopathy and in patients with ischemic cardiomyopathy who have failed an endocardial approach. For these patients, referral to a center that has extensive experience with epicardial ablation should be considered to optimize outcomes and decrease procedural risk.
References:
- Shivkumar K, Bradfield JS. Epicardial sblation of VT: minimizing risks & improving success. Talk presented at: 40th Heart Rhythm Scientific Sessions; May 8-11, 2018; San Francisco, CA. https://www.abstractsonline.com/pp8/#!/5753/presentation/21378.
- Sosa E, Scanavacca M, D'avila A, Pilleggi E. A new technique to perform epicardial mapping in the electrophysiology laboratory. J Cardiovasc Electrophysiol. 1996;7(6):531-536. https://doi.org/10.1111/j.1540-8167.1996.tb00559.x.