Fluoroless Techniques in the EP Lab: Update

This year marks the fourth year of utilizing zero fluoroscopy during catheter ablation at Advocate Illinois Masonic Medical Center. Is it ready for primetime?

Catheter ablation of cardiac arrhythmias has conventionally been performed with the aid of fluoroscopy to direct catheter placement. Unfortunately, the use of fluoroscopy comes with radiation risks to the patient as well as to the electrophysiology (EP) lab staff. Radiation exposure has been linked to an increased incidence of malignancies, skin injuries, genetic defects, and cataracts.

As the number of arrhythmias that have indications for catheter ablation increases, more patients are undergoing catheter ablation procedures for atrial fibrillation, atrial tachycardia, and ventricular tachycardia. These complex ablation procedures are often longer in duration and have been fraught with increased fluoroscopy times. Moreover, some patients undergo pre-procedural CT scans to define cardiac and extracardiac anatomy, while others go through multiple ablation procedures. Both factors result in substantial cumulative radiation exposure. Another concern related to traditional catheter ablation is that the EP staff participating in ablation procedures involving fluoroscopy have an increased risk of orthopedic injuries related to the protective lead garments. 

Given these radiation- and orthopedic-related concerns, a focus on developing techniques to reduce or eliminate the need for fluoroscopy during catheter ablation procedures has never been of greater importance. Over the years, a number of investigators have reported on techniques using adjunctive imaging technologies to try to reduce or eliminate the need for fluoroscopy during catheter ablation. Real-time 3D transesophageal echocardiography (TEE) and magnetic resonance imaging (MRI) have been utilized to reduce radiation time, but these techniques are invasive and not widely available. However, as most EP labs are already employing catheter-based 3D electroanatomic mapping (EAM) as well as intracardiac echocardiography (ICE), maximizing the value of these adjunctive technologies to reduce fluoroscopy should be considered a goal for all electrophysiology laboratories. With such an aim in mind, I performed my first completely fluoroless catheter ablation procedure in July 2010, in which absolutely no fluoroscopy was used during a case of atrial flutter. The technique was honed over time, and since December 2010, we have not used any fluoroscopy during any of our catheter ablation procedures. We have performed more than 300 consecutive fluoroless ablation procedures.

In 2012, my colleagues and I reported on the safety, efficacy, and feasibility of performing fluoroless catheter ablation on an unselected patient group of a variety of arrhythmias that presented to our EP laboratory. We compared 60 consecutive patients who underwent a fluoroless catheter ablation with 60 consecutive patients who underwent a conventional catheter ablation using fluoroscopy in addition to EAM and, in some cases, ICE. Based on those findings, we noted that completely fluoroless catheter ablation, which relies on intracardiac electrograms (IE), ICE, and EAM for catheter positioning and tracking, is both a safe and effective means of treating a wide variety of arrhythmias in adults. The 3D EAM allows the operator to visualize catheter positioning within the heart in multiple projections. When ICE is employed, direct visualization of most intracardiac structures can be achieved and tissue apposition during catheter ablation can be monitored. When the operator places a greater reliance on these adjunctive imaging modalities to perform the procedure, the precision and versatility of this technique may be superior to a traditional fluoroscopic approach in which ICE and EAM are sometimes used as afterthoughts.

I am pleased to see that we have been able to perform complex ablation procedures without compromising our patient outcomes or incurring complications related to the absence of fluoroscopy. We have performed nonfluoroscopic catheter ablation for ischemic ventricular tachycardia, via both retrograde aortic and transseptal approaches. Perhaps equally as important, our procedure times have dropped significantly over the past two years. For example, our average procedure times for ablation of paroxysmal AF have dropped to approximately two and a half hours, for atrial flutter to less than one hour, and for AVNRT or AVRT to one to two hours. Our procedure times for post-AF atrial tachycardia and VT have also diminished significantly; this is noteworthy, as these two arrhythmias often carry with them high fluoroscopy times and operator/staff fatigue due to the length of time the lead garments are worn. My team has performed fluoroless catheter ablation on a number of patients with cardiac pacemakers and defibrillators, including CRT devices, avoiding lead dislodgement through the use of ICE. 

The fluoroless approach is one that can be learned by any operator and lab staff with the desire and commitment to optimize their current practices. Cardiac electrophysiology fellows at our training program feel comfortable with the fluoroless catheter ablation procedure within the first month or two of their fellowships. Physicians coming from other institutions in the U.S. and from overseas to observe the fluoroless catheter ablation procedure at Advocate Illinois Masonic Medical Center often mention that they are eager to implement the same technique in their respective labs. Perhaps one of the understated advantages of the fluoroless approach is that the tools and technology required are already embedded in most EP laboratories, so no additional financial investments need to be made to get a fluoroless program off the ground. 

With the exceptions of arrhythmias of an epicardial origin, all other tachyarrhythmia types have been ablated successfully at our institution using the fluoroless approach. 

What follows is a “how to” guide for performing a fluoroless catheter ablation. It is my hope that this technique will be widely employed in the years to come. 

PREPARATION

Fluoroless catheter ablation procedures are performed in a traditional EP laboratory equipped with single-plane fluoroscopy, so that this technology is available should the need arise. Most of the procedures are performed with conscious sedation, with general anesthesia being used for some cases of atrial fibrillation ablation and ventricular tachycardia. The operator, EP lab staff, and anesthesia team do not wear protective lead garments during the procedure, thereby lessening fatigue and pain as well as decreasing the risk of orthopedic injury. Protective lead garments are readily available in the room in the event that fluoroscopy needs to be used. 

EAM is used for all fluoroless catheter ablations. ICE is used for ablation for most cases of atrial flutter, occasional cases of SVT, and atrial fibrillation and ventricular tachycardia cases. 

VASCULAR ACCESS

Percutaneous femoral venous access for placement of the introducer sheaths is performed by the modified Seldinger technique under the aid of vascular ultrasound for all patients. This same technique is utilized for femoral arterial access for ablation of left ventricular tachycardias.

CATHETER POSITIONING

For cases that involve intracardiac ultrasound, a phased-array ICE catheter is advanced through a sheath in the femoral vein. The ICE catheter is advanced through the femoral vein and into the external iliac vein. An echo clear space is maintained at the transducer’s tip during advancement of the ICE catheter toward the right atrium (Figure 1). 

For most cases, a deflectable decapolar catheter is advanced through the femoral vein and into the IVC under the guidance of the EAM system. Geometry of the IVC is collected at this time. When electrograms are first noted on the distal bipoles of the catheter, the catheter tip has reached the border of the IVC and inferior right atrium. The catheter is then advanced superiorly into the right atrium. A loss of electrogram signals noted on all but the very proximal poles of the decapolar catheter signifies that the catheter is approximating the border of the superior RA and SVC. The geometry of the SVC is collected and the decapolar catheter is then withdrawn into the right atrium and manipulated under EAM guidance to collect the geometry of the right atrium. The right atrial appendage and coronary sinus ostium are delineated. The decapolar catheter is often placed in the right ventricle and used to create geometry of the right ventricle and right ventricular outflow tract, if needed (Figure 2). If ICE is employed, it serves as an additional tool to assure the accuracy of the EAM geometry model. The decapolar catheter is usually advanced last into the coronary sinus (CS). The CS is cannulated by manipulating the catheter so that the tip is in the posteroseptal region of the right atrium under EAM guidance. When EGMs compatible with the CS ostium are noted in this region, the catheter tip is placed into the CS. 

The geometry created with the deflectable decapolar catheter serves as a shell whereby the remaining diagnostic and ablation catheters can be positioned appropriately. 

TRANSSEPTAL PUNCTURE

To perform the fluoroless transseptal puncture, a 180 cm J-wire 0.032” is inserted into the right atrium through a short introducer sheath in the femoral vein. Once the tip of the wire is confirmed to be in the right atrium under ICE, the short sheath is withdrawn and exchanged for a transseptal sheath-dilator assembly. This assembly is then advanced over the 180 cm wire approximately 4 to 8 inches, depending on patient size, aiming to have the tip of the assembly in the mid IVC. The wire and dilator are then removed and an ablation catheter is advanced through the transseptal sheath. Once the ablation catheter’s electrodes have advanced beyond the tip of the transseptal sheath, the ablation catheter becomes visible on the EAM; the ablation catheter can then be advanced into the SVC using the previously created geometry as the guide. The transseptal sheath is subsequently advanced over the ablation catheter until a deflection artifact is noted on the EAM system, thus confirming the sheath’s location in the SVC. The ablation catheter is removed and the J-wire and dilator are placed through the sheath with the J-wire tip four inches beyond the end of the dilator tip to prevent trauma to the SVC or heart by the dilator. Once the dilator has been inserted, the wire is removed and the transseptal needle is placed in the sheath-dilator assembly. The transseptal assembly is withdrawn until the tip is seen on the ICE to cause tenting of the interatrial septum in the region of the fossa ovalis. The preferred location for most transseptal punctures is one in which tenting of the interatrial septum is seen in an ICE view clearly showing both of the left-sided pulmonary veins. Such a location greatly reduces the chances of a puncture that is too anterior with attendant risk of aortic puncture or too posterior with associated risk of posterior left atrial wall puncture. The transseptal puncture is performed under ICE guidance and the needle tip is seen in the left atrium. Saline bubbles from the flush line through the transseptal needle are seen in the left atrium on ICE. Hemodynamic pressure monitoring also confirms left atrial entry. 

LEFT ATRIAL CATHETER POSITIONING

For ablation of atrial fibrillation, left-sided atrial tachycardias, and left-sided accessory pathways, a transseptal puncture is performed and geometry of the left atrium is collected by manipulating the ablation catheter or circular mapping catheter under EAM and ICE guidance. In this same fashion, a geometry of the pulmonary veins and left atrial appendage can be created. 

VENTRICULAR AND OUTFLOW TRACT CATHETER POSITIONING 

For right ventricular outflow tract tachycardias, the right ventricular and right ventricular outflow tract geometries are collected on EAM using a deflectable decapolar catheter under ICE guidance. 

For left ventricular outflow tract tachycardias, atrial and ventricular tachycardias originating from the coronary cusps of the aortic valve, as well as for some left ventricular tachycardias, femoral arterial access is obtained under ultrasound guidance. Next, an ablation catheter is advanced retrograde through the femoral artery, into the iliac system, and into the aorta, all under EAM guidance. Geometry of the arterial system is collected as the ablation catheter is advanced retrograde through the abdominal aorta, descending thoracic aorta, aortic arch, and ascending aorta. The catheter tip is flexed to create a distal U-curve, which can be confirmed by noting a reversal of sequence of the distal electrode numbers on the EAM. This U-curve is used to advance the catheter around the aortic arch and cross the aortic valve. The aortic valve is crossed by prolapsing the catheter across the valve under ICE guidance. Once across the valve, a geometry of the left ventricular outflow tract and left ventricle can be created under ICE guidance. 

For some cases of left ventricular tachycardia, a transseptal approach is used to access the left atrium. The ablation catheter can then be advanced from the left atrium into the left ventricle under ICE guidance. 

CATHETER ABLATION

Stable catheter position and adequate contact during ablation can be confirmed on EAM and/or ICE. ICE can be used for monitoring lesion formation. Critical structures such as coronary artery ostia can be clearly delineated on the ICE and marked on the EAM.

CONCLUSION

Based on our experience, we wholeheartedly feel that fluoroless catheter ablation is the correct direction for EP in the years to come, due to the significant benefits both acutely and in the long term for patients, EP lab staff, and physicians. The fluoroless approach should be considered not only for certain populations, such as pregnant, obese, or pediatric patients, but for all patients, as we know that the method is safe, effective and feasible.