The PentaRay^® NAV (Biosense Webster, Inc., a Johnson & Johnson company) (Figure 1) became available in 2012 and was recommended for use in cases of atrial tachycardia, ventricular tachycardia, and complex fractionated electrograms in atrial fibrillation (AF). One of the main advantages with this mapping catheter is the atraumatic splaying of all five spines against the endocardial surface, providing a high-density map from its 1-mm electrodes covering a surface diameter of 3.5 cm.

AF ablation is frequently performed with a circular shaped catheter, which is positioned within the pulmonary veins to assess for entrance and exit block. While this shape facilitates acquiring electrogram signals circumferentially in a pulmonary vein, some veins are too small to enter. 

In this article we discuss the advantages and disadvantages of using a PentaRay catheter during AF ablation, as well as describe techniques in mapping. 

Case Study

The patient is a 62-year-old male with hypertension and persistent atrial fibrillation. Due to the large atrial diameter of 5.5 cm, a Convergent approach was utilized to treat his atrial fibrillation. Through a subxiphoid approach, the nContact EPi-Sense^™ AF Guided Coagulation System was used to ablate the posterior wall and the left atrium anterior to the right and left pulmonary veins from an epicardial approach. Following the surgical portion of the procedure, transseptal access was obtained and a PentaRay catheter and ablation catheter were placed into the left atrium. The PentaRay catheter was used to obtain geometry and voltage of the left atrium and pulmonary veins. As expected, the posterior wall had a large area of scar from the epicardial ablation lesion set. Ablation was performed around the superior portions of the left and right pulmonary veins and outside the right inferior pulmonary vein to obtain bidirectional block across the pulmonary veins. The patient continued to be in atrial fibrillation; therefore, complex fractionated atrial electrograms were targeted and ablated. A right atrial cavotricuspid isthmus line was then created, and the arrhythmia organized into a focal atrial tachycardia. The PentaRay catheter was used to map the tachycardia, which was localized to the base of the left atrial appendage where radiofrequency energy was applied. The tachycardia terminated and normal sinus rhythm was restored. 

Fast Anatomical Mapping and Construction of the Left Atrial 3D Anatomy

A circular mapping catheter such as the Biosense Webster Lasso^® NAV catheter may be used to quickly acquire 3D anatomy during AF ablation; however, the PentaRay provides a higher density map of the left atrium. This is particularly useful in ablations in which a scar map is desired. For example, in Convergent AF ablations using the nContact EPi-Sense^™ AF Guided Coagulation System, ablation lesions are created across the posterior wall. A detailed map to delineate scar is useful to plan where to create the endocardial lesions to connect these scars (Figure 2). While a circular mapping catheter can quickly acquire anatomical and electrogram data, it may slightly overestimate left atrial geometry since the catheter generally appears the same whether it is floating, pressed lightly against atrial tissue, or pressed with enough force to stretch the atrial wall outward. There may be less deformation of the left atrium during shell acquisition, since the splines of the PentaRay provide a visual indication as to tissue contact because it takes on a flat shape as the catheter is pressed up against the atrial wall. Importantly, the geometry created at the ridge between the left superior pulmonary vein and the left atrial appendage is excellent using a PentaRay catheter. Additionally, the PentaRay catheter is able to enter and create detailed geometry for smaller pulmonary veins that a circular mapping catheter may have difficulty entering. (Figure 3) Another feature of the PentaRay design during mapping is that catheter entrapment by the mitral valve apparatus is much less of a concern, since there is no loop in the PentaRay as opposed to a circular mapping catheter.

Assessing for Gaps in PVI

Placement of a circular mapping catheter with the bipoles circumferentially located allows the operator to quickly assess the location of the earliest breakthrough into a pulmonary vein. This is certainly an advantage of the Lasso catheter shape; however, there are a number of techniques that may be employed when a PentaRay catheter is used instead for AF ablation. In certain sized pulmonary veins, the PentaRay catheter may be inserted into the vein, the five splines may sit circumferentially, and the earliest point of breakthrough can be determined. However, if the splines easily prolapse forward deeper into the vein, the spatial separation between the splines may be lost and identification of the relative earliest electrogram signal is not possible. One technique to try and keep the splines spread apart in the vein ostia or antrum is to first place an ablation catheter into the vein and then advance the PentaRay catheter on top of it at the vein ostium. If one cannot place the PentaRay at the ostium with good separation between the splines, activation mapping can identify the breakthrough in the PVI line. Pacing can be performed from, for example, the mid-coronary sinus during sinus rhythm and an activation map may be acquired with points taken at multiple areas inside the ablation line, at the pulmonary vein ostia and in the pulmonary veins (Figure 4). Playing a propagation map will easily identify the gap in ablation (Figure 5). 

Another method of assessing for gaps in PVI lines is to drag the ablation catheter over the ablation line and look for split double potentials during either sinus rhythm or atrial pacing from the mid-coronary sinus. As you approach the gap with your mapping catheter, the time between the split potentials will decrease. The gap in ablation may have a continuous or fractionated signal. The PentaRay catheter can also be used to map for the double potentials and for the gap in line of block. This technique is possible if there is atrial tissue on both sides of the ablation line, and is more useful in ablation lines that are placed antrally away from the pulmonary vein ostia (i.e., for wide antral circumferential ablation). If the ablation lesions are placed at the vein ostium/antrum, then double potentials will likely not be seen. 

Post PVI Atrial Tachycardia Mapping

Due to the dense spacing of the electrodes, the PentaRay catheter is particularly useful in mapping focal atrial tachycardias that may be seen during an AF ablation case. The radial construction of the PentaRay allows one to quickly and accurately identify a focal point source. This may also prove very useful when mapping for triggers that initiate AF. 

PentaRay and Adenosine Testing

The administration of adenosine after achievement of pulmonary vein isolation has been used to identify partially ablated, viable tissue. It is hypothesized that adenosine causes hyperpolarization of the cell membrane, shortening of the action potential and thus recovery of dormant conduction.¹ When using adenosine to check for pulmonary vein isolation, a Lasso catheter positioned circumferentially at a pulmonary vein ostium may be able to identify the region of recovered conduction more readily if reconnection is transient. Since the PentaRay catheter splines tend not to lay circumferentially across a vein ostium, one may need to employ other techniques. One is to place the PentaRay at the earliest site of activation just prior to achievement of block since this may be a likely site for reconnection. Another option is to place the PentaRay at the carina of one set of veins (Figure 6). Splines of the PentaRay would therefore reach into both veins. One could try and perform an activation map in the vein of most likely reconnection as the adenosine is used; however, if the reconnection is transient, this may be difficult. Additional administrations of adenosine may be used to hone in on the site of reconnection; however, we have noticed that not infrequently, reconnections may last for a significant period of time after adenosine administration. Once it is determined that a certain vein has reconnected, other catheters such as the ablation catheter may be placed into that vein to aid in targeting the region of reconnection. 

Summary

The PentaRay NAV mapping catheter is a versatile tool in the ablation of AF. Its ability to create a detailed and accurate 3D anatomical and scar map of the left atrium and pulmonary veins, map focal atrial tachycardia sources, and allow worry-free manipulation (i.e., from catheter entrapment) have made it a preferred catheter of ours. 

Disclosures: The authors have no conflicts of interests to report regarding the content herein. 

Editor’s Note: This article underwent peer review by one or more members of EP Lab Digest^®’s editorial board.

Reference

1. Arentz T, Macle L, Kalusche D, et al. ‘Dormant’ pulmonary vein conduction revealed by adenosine after ostial radiofrequency catheter ablation. J Cardiovasc Electrophysiol. 2004;15:1041-1047.