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The Catalyst

Hybrid procedure offers positive benefits for persistent AF in patients

By Mikie Hayes
Public Relations


In what is considered to be a best–of–both worlds approach, an innovative collaboration among two heart surgeons and an electrophysiologist has resulted in MUSC performing its first thoracoscopic MAZE procedure with a novel technology to treat atrial fibrillation.

Mario Castillo-Sang, M.D.

The Maze procedure was created in the late 1980s by James Cox. According to Mario Castillo–Sang, M.D., assistant professor of surgery, MUSC Division of Cardiothoracic Surgery, it was the first surgical procedure to treat atrial fibrillation and has since undergone several iterations. Today, for instance, energy sources are used instead of cutting and sewing the heart. “The efficacy is very good even long–term, but it does require a full cardiopulmonary bypass run and cardioplegic arrest of the heart to perform all the lesion set. That is where the hybrid approach comes in,” he said.

The 62–year old patient, who underwent the hybrid procedure, had suffered with long–term, persistent atrial fibrillation, also known as AF or Afib, and had not benefitted previously from typical treatments. Touted as being less invasive with a shorter recovery, the hybrid surgery was conducted on a Tuesday and the patient was home on Sunday. According to Minoo Kavarana, M.D., associate professor in Pediatric Cardiothoracic Surgery, who was involved in both the surgery as well as initially bringing the surgery to MUSC, the stay can be as short as three days.

Kavarana is extremely optimistic about the prospects of offering this type of surgery to his patients. “In three to four hours, we can minimize time, risks associated with invasive surgery, trips to the EP lab, not to mention the risk of stroke.”

AF is the most common cardiac arrhythmia — or rhythm disturbance — and occurs when the electrical impulses controlling the heartbeat become disorganized, causing an irregular, fast heartbeat. It currently affects over 5 million Americans and is projected to reach a prevalence of approximately 12 million people by the year 2050.  

AF is a serious cardiac condition. It increases the risk of stroke by five times. The chance of developing atrial fibrillation increases with age, and people 40 years of age or older have a 1–in–4 chance of developing it in their lifetime.

Cardiac ablation is the common technique used in the treatment of AF. Ablation works by scarring or destroying tissue in the area of the heart that triggers an abnormal heart rhythm. In some cases, ablation prevents abnormal electrical signals from traveling through the heart thereby stopping the arrhythmia.

Cardiac ablation is typically done in an EP lab where the electrophysiologist, a cardiologist who specializes in heart rhythms, threads long, flexible tubes, known as catheters, through a vein in the groin and up to the heart and corrects the structural problems that are responsible for the arrhythmia.

Other times, typically in cases of long–standing persistent AF, open-heart surgery may be necessary. During this surgery, the breastbone is separated to allow access to the chest, the heart is stopped and a heart-lung machine is used. Scissors are used to open the pericardium to gain access to the heart. This procedure is considered the most invasive.

Now, there is a third option – hybrid ablation – for these persistent cases. Using a thorascopic approach, the minimally invasive surgery is performed through small keyhole incisions made between the ribs, through which a tiny camera and video-guided instruments are inserted. A cardiac surgeon makes epicardial lesions outside the heart, where catheter manipulation can be difficult. Subsequently, during a separate procedure, an electrophysiologist ablates endocardial tissue inside the heart.

This procedure eliminates the need for separating the breastbone, the heart to be stopped or heart-lung machine to be used, resulting in faster recovery time and a lower risk of infection associated with open-heart surgery. The combined approach is said to increase the likelihood of blocking irregular electrical circuits and improve success rates for patients with certain types of persistent AF who want a minimally invasive treatment option.  

Those who have symptomatic AF and have been in AF for a long period of time or have a large left atrium or have failed multiple catheter ablations are appropriate candidates for this procedure.
 

Frank Cuoco, M.D.

Frank Cuoco, M.D., assistant professor in the Division of Cardiology, and the electrophysiologist who was involved in this first procedure, explained, “Atrial fibrillation is an irregular rhythm from the top of the heart that is similar to a rippling pond.Typically, pebbles, or triggers, start the rippling. Most normal hearts will stop rippling on their own after a while if the pebbles — or triggers — stop hitting the electrical ‘pond’ of the heart muscle. We call this paroxysmal AF. However, in patients with persistent AF — that is, it does not stop rippling on its own without shocking the heart back into rhythm —  there are electrical abnormalities in the substrate or pond of the heart that promote ongoing rippling and cause the AF to persist indefinitely.”  

Catheter–based procedures are usually very good at targeting the triggers for AF, as these triggers or pebbles most often originate from the pulmonary veins, which bring back the blood from the lungs to the heart. Electrically insulating or isolating these pulmonary veins is the primary goal of AF ablation, but in patients with persistent AF, there are often many more abnormalities in the substrate of the heart that need to be modified in order to achieve long-term rhythm control. Cuoco said, “The catheter–based ablation approaches these triggers and substrate from the inside of the heart, but often it is difficult to achieve full thickness and or permanent ablation of the heart tissue from the inside alone.”

The hybrid procedure has the advantage of allowing the physicians to better target the triggers, but even more importantly, it targets the areas in the heart that promotes the continued AF. 

“This combined approach, said Cuoco, “optimizes the best of both procedures, as each is good at targeting particular areas in the heart that serve as triggers or substrate for AF, but not as good as the other in other areas. This is similar to using a ‘George Foreman Grill’ approach to effectively burn or ablate the heart tissue from both sides; as with a well done steak, you need to cook it all the way through in order to make permanent burns that will interrupt the electrical signals that initiate and sustain atrial fibrillation.”

This tailored approach plays an important role in the treatment of patients with persistent AF. Castillo–Sang said, “Right now this procedure is not widely disseminated. We are the only center in the Tri-county area offering a hybrid approach. We know it has huge potential for patients as it offers a very good success rates in the way of AF — freedom of 83 percent at three years in some of the larger more recent series.  This compares favorably to multiple endocardial ablations and open heart surgery.”

He continued, “This is a safe and effective approach to cure patients from atrial fibrillation that also allows for quicker recovery and less trauma from surgery. It has huge benefits for the patient. A more comprehensive approach in which some of the lesions that are very difficult to create endocardially are performed epicardially with minimally invasive surgery and vice versa.”

Kavarana agreed, “Hybrid ablation makes sense because it combines the most effective aspects of AF surgery and catheter ablation. We can achieve higher success rates and fewer complications because cardiac surgeons and EPs can both ablate areas of the heart that are best suited to their specialties’ particular approaches.”

Minoo Kavarana, M.D.

MUSC has installed a hybrid suite with surgical and EP equipment. This area will eventually house everything necessary to both perform the hybrid procedure as well as incorporating electrophysiological testing to confirm that the erratic electrical signals have been blocked. According to Castillo–Sang, the hybrid suite offers the availability of immediate radiographic fluoroscopic imaging, which allows for real–time visualization needed for the catheter ablation procedure in the same operating suite where the surgical part of the procedure is performed.

Only a handful of centers around the U.S. are performing hybrid ablations currently. Previously, some thought this procedure might generate a turf war between cardiac surgeons and EPs. At MUSC that is not the case; this procedure represented a true collaboration that ensured the patient received the best treatment possible for his particular condition.

Kavarana, Cuoco and Castillo–Sang all believe the hybrid procedure holds great promise and opportunities to offer patients a procedure than may be better suited for their particular condition.

MUSC will also be involved in the landmark Dual Epicardial Endocardial Persistent Atrial Fibrillation trial, known as DEEP AF, that should begin within the next six to 12 months. This pivotal study will look at the potential benefits of the hybrid approach to AF ablation compared to standard therapies.

October 30, 2014

 

 
 
 

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