By John D Day
Complications are never something we want to talk about, yet they are always in the back of our minds. Despite the latest and greatest techniques, we will never be able to completely escape the risk of a potential complication.
As I have been asked to defend a number of colleagues when things go wrong in the electrophysiology lab, it is particularly sad to watch when these unfortunate complications have turned into lawsuits. Lawsuits can chase electrophysiologists for years until they are finally resolved. No one can explain the mental torment and anguish that hang over a physician during these years unless you have experienced it yourself.
Certainly, if we can minimise the risk of a complication up front, then we can save ourselves from having to experience a bad procedural outcome. It goes without saying that we have to prepare ourselves for each and every case. This includes getting enough sleep the night before the case and minimising distractions during the procedure.
Studies have shown that sleep deprivation may be worse than alcohol intoxication on affecting our mental judgment and fine motor skills. Indeed, one study showed that surgeons were 83% more likely to experience a complication when sleep deprived (JAMA 2009; 302:1565-1572). This not only includes the attending physician, but fellows who may be participating in the procedure.
Equally important, is to reduce distractions in the electrophysiology lab. It is all too common to hear pagers going off, phones ringing, equipment alarms sounding, etc. These distractions of our modern world have already been shown to have an impact during cardiac surgery (Perfusion 2011; 26:375–80).
Once we have prepared ourselves physically and mentally for an atrial fibrillation ablation procedure, there are five basic things we can do to minimise the risk of a serious complication.
Do not ablate inside pulmonary veins
This seems simple to do but we still see this complication arise. In the past, pulmonary vein stenosis was reported to occur in three to 42% of cases. Now, fortunately, that risk is less than 1%. I have reviewed cases where young, physically active patients have become crippled following their elective ablation procedure with severe life-long shortness of breath from recurrent pulmonary stenosis despite multiple-stent procedures. Use imaging techniques that you are comfortable with, know where your ablation catheter is at all times, and do not ablate inside the pulmonary veins.
Create a phrenic nerve pace map
Fortunately, this is another rare complication and when it does occur it generally resolves with time. I personally experienced this complication once and it was devastating. My patient became horribly short of breath with any exertion. Fortunately, this resolved six months later and I swore that I would never let it happen again! I now perform phrenic nerve pacing around the right-sided pulmonary veins and carefully map out where phrenic nerve capture is obtained and then avoid ablation in those areas. Indeed, when we performed phrenic nerve pacing in 137 consecutive patients referred for atrial fibrillation ablation, we found that we could capture the phrenic nerve in 13% of the patients in the body of the left atrium outside of the pulmonary veins.
Anticoagulate, anticoagulate and anticoagulate!
Strokes can be devastating. The key to stroke prevention is simple–anticoagulate prior to the procedure (or perform a transoesophageal echocardiography [TEE]), during the procedure including full anticoagulation prior to the transseptal, and after the procedure. If proper attention is given to anticoagulation, sheath management and proper use of the ablation catheter, then the risk of stroke can be dramatically reduced.
Gentle catheter manipulation
The number one cause of death from atrial fibrillation ablation is cardiac perforation and tamponade. The key to preventing cardiac tamponade is gentle catheter manipulation. You have to have significant respect for the very thin walled left atrium. Sheaths in the left atrium increase this risk by making the catheter much stiffer. Likewise, excessive contact or prolonged ablations in the same location may cause a steam pop and tamponade. I have seen cases where patients have “crashed” within seconds-fortunately, all patients did well after tamponade was treated. Have everything you need to treat this complication ready ahead of time.
Limit energy to the posterior wall
Perhaps the most dreadful of all atrial fibrillation ablation complications is that of an oesophageal injury. Sadly, many electrophysiologists do not take the necessary precautions until they have experienced this complication.
Unfortunately, when speaking or writing on how to prevent this complication, most experts only mention limiting power to the posterior wall. Power is only one variable and alone it means nothing. The only way to minimise the risk of an oesophageal injury or peri-oesophageal nerve injury is to reduce energy delivery to the posterior wall of the left atrium. Energy is a function of power times time (E=PxT) which can be affected by catheter contact.
In addition, energy delivery to the posterior wall occurs by conductive heating which is a time dependent process. Thus, our approach has been to deliver energy at a high power setting for a very short period of time. In this way, energy can be focused to the left atrium rather than transmitting the energy deeper by conductive heating. Regardless of how you like to set the radiofrequency generator, the key is to limit energy to the posterior wall.
John D Day is medical director, Intermountain Heart Rhythm Specialists, Murray, USA