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Pericardial access with subsequent epicardial mapping and ablation of VT is an important tool in the armamentarium of invasive electrophysiologists. Sosa and colleagues first reported the percutaneous method of accessing the pericardial space to perform epicardial ventricular mapping and ablation in 1996.1 This approach, described in detail in a previous chapter, relies on the insertion of a needle into a “virtual space” — that is, the space between the parietal and visceral pericardium. Unfortunately, adhesions related to prior cardiac surgery or pericarditis may obliterate this space, thereby complicating pericardial access and mapping after open-heart surgery. The magnitude of this problem, that is, the need for epicardial access in patients with prior cardiac surgery, is unclear but has the potential to be significant. Recent work has suggested that approximately one-third of patients with prior myocardial infarction have epicardial substrate for VT,² and a strategy of first-line endocardial and epicardial ablation results in greater freedom from recurrent VT^2,3 when compared to an endocardial approach alone. As approximately 30% of patients with VT related to coronary artery disease have had prior coronary artery bypass surgery,⁴ it is inevitable that practicing electrophysiologists at high-volume centers will be faced with obtaining epicardial access at some point in their practice. Furthermore, the need for epicardial ablation in patients with nonischemic cardiomyopathy (NICM) is well known, with some patients with NICM having undergone prior valve replacement. Additionally, in situations where both mechanical mitral and aortic valve replacement has been performed, epicardial access may be the only approach to manage VT with catheter ablation.⁵ In this chapter, we will describe our approach to obtaining epicardial access and mapping/ablation in patients who have undergone cardiac surgery. In this situation, 3 options exist for epicardial mapping and ablation: (1) limited epicardial mapping via the coronary venous system, (2) percutaneous access, and (3) surgical epicardial access.

Limited Epicardial Mapping from the Coronary Venous System

In select patients who have undergone prior cardiac surgery, mapping the coronary venous system may be beneficial given the epicardial nature of this structure. For example, Obel et al.⁶ reported on the utility of this approach for the ablation of idiopathic outflow tract VTs, whereas Doppalapudi and colleagues reported on the utility of this approach for the ablation of idiopathic VTs originating from the crux of the heart.7 While potentially valuable, this approach has significant limitations including partial access to the left ventricle based on individual variation in the CS anatomy. Moreover, even when a target is located, potential complications of ablation such venous stenosis, rupture, thrombosis, or collateral injury to an adjacent coronary artery may limit the use of this approach. Reduction of RF power applications (to 20–25 W) during ablation may improve the safety of ablation with this approach. While this approach does allow one to undertake limited epicardial mapping when all else fails, in many patients, the region of interest is not accessible with coronary venous system mapping, particularly in scar-related VT. In these circumstances, access to the pericardial space is necessary.

Percutaneous Access with Limited Epicardial Mapping

Pericardial adhesions frequently develop after cardiac surgery and limit entrance to and mapping within the pericardial space. In general, the anterior aspect of the pericardium is opened during cardiac surgery. As such, dense adhesions tend to form particularly in this anterior region. Thus, the key to obtaining pericardial access in these patients is to select an inferior approach angle with the needle in order to enter adjacent to the inferior wall of the heart⁸— a region that typically has less adhesions. Furthermore, it is our experience that fewer adhesions tend to form along the AV groove as compared to the more apical portion of the pericardial space. Thus, one should make sure the inferior puncture is guided towards the base of the heart, parallel and close to the CS catheter, which constitutes an excellent landmark to guide the puncture. Practically speaking, the use of a left anterior oblique, anteroposterior, or lateral view can aid the operator in positioning the needle inferiorly prior to entering the pericardial space (Figure 47.1A). If necessary, a RAO view should be used to confirm a basal rather than apical epicardial entrance point.

As with the traditional approach described in a previous chapter, once the pericardial space is entered, contrast is injected to confirm the location and a guidewire advanced (Figure 47.1B). In this situation, the contrast injection forms a pool of contrast along the inferior wall of the heart (Figure 47.1C) instead of quickly spreading around the heart silhouette, which typically happens when one approaches the pericardial space free of adhesions. It is also important to note that it may be impossible to advance the guidewire to encircle the entire cardiac shadow—a fluoroscopic sign that is frequently used to confirm that the pericardium is entered. As such, one must be confident that the pericardium is entered prior to advancing the sheath in order to avoid inadvertent sheath placement in the right ventricle. Thus, it is reasonable to advance a 5-Fr introducer over the wire, which will allow for further injection of small amounts of contrast in order to confirm pericardial access and/or allow for further manipulation of the guidewire. In situations where one is unable to advance a sheath over the wire due to adhesions, it may be necessary to utilize a stiff guidewire to lyse the adhesions (Figure 47.2). In this situation, concomitant use of echocardiography and fluoroscopy to ensure one is in the appropriate tissue plane and allow for early recognition of complications such as a pericardial effusion.⁹

Adhesions may be present along the inferior surface of the heart. In general, these adhesions tend to be “looser” than the dense anterior adhesions. The operator may increase the region available to map by breaking these adhesions with the ablation catheter. Deflection and extension of the ablation catheter can typically break these inferiorly located adhesions (Figure 47.1D). While one may attempt this maneuver anterolaterally, it is frequently less successful given the density of the adhesions in this location; however, it is not unreasonable to attempt this as it may increase the mappable region.

A percutaneous route is our first option for postsurgical patients requiring epicardial mapping. Despite the limited region available to map, this approach is still quite valuable as epicardial VT circuits in the setting of coronary artery disease are more prevalent in patients with prior inferior infarction,¹⁰ a region that may be accessed with this approach. Additionally, this approach is less “invasive” than the surgical approach described below.

Surgical Access with Limited Epicardial Mapping

Occasionally postsurgical adhesions may be so dense resulting in total obliteration of the “virtual space” between the visceral and parietal pericardium. In this situation a surgical approach to expose the pericardial space may be the only available option as percutaneous access will be impossible in the absence of this “virtual space.” Two approaches have been described: a subxyphoid approach and limited anterior thoracotomy.^11,12

The experience of Soejima and colleagues with the surgical subxyphoid approach is similar to ours.¹¹ This approach can be carried out in the electrophysiology laboratory employing general anesthesia and a sterile technique. We always enlist the help of our cardiac surgical colleagues when this access is required. Briefly, an incision (approximately 3 inches) is made in the midline epigastrium and carried down to the linea alba. This incision is usually made to the left of the xyphoid process, although in some cases it may be necessary to remove the xyphoid process in order to obtain improved access. Once the pericardium is identified, a pericardiotomy is performed and extended to ensure adequate visualization of the ventricle. Blunt dissection, sometimes with the surgeon’s finger, is performed under direct visualization to lyse adhesions, thereby exposing as much of the inferior and posterior epicardial surface of the ventricle. At this point, an 8-Fr sheath is then placed in the pericardial space to allow placement of the ablation catheter within this region for mapping and ablation (Figure 47.3). This approach usually adds an additional 30–40 minutes of time to the procedure.

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