INTRODUCTION

Percutaneous epicardial access is widely used in the field of electrophysiology for the treatment of complex arrhythmias as well as for closure of the left atrial appendage.¹ Nonetheless, epicardial access into the “virtual” pericardial space requires expertise and extensive knowledge of the anatomy to prevent complications. Different techniques have emerged as well as different percutaneous approaches, including subxiphoid, parasternal, intercostal, apical,² transesophageal,³ transatrial,^4,5 and transbronchial.⁶ Among all these approaches, the subxiphoid access is the most frequently used, as multiple studies have assessed its efficacy and safety. Despite being a minimally invasive access, subxiphoid approach still carries the risk of inadvertent right ventricular perforation causing pericardial bleeding, which is the most common complication of epicardial access, having an incidence ranging from 3.7% to 10%.^7–9 Several efforts have been made to minimize complications arising from epicardial access, including use of different access needles, multimodality image integration, and evaluation of changes in pressure frequency to recognize pericardial entry.

Originally, epicardial procedures were performed using a 17- to 18-gauge Tuohy needle. However, in recent years, a modification of this approach has emerged with a 21-gauge micropuncture needle with or without a short 18-gauge needle (“needle-in-needle” technique), leading to a significant reduction of major bleeding when cardiac and vascular puncture accidentally occurs.¹¹

The pressure frequency concept is based on the variation of pressure within different tissues during the epicardial access. This strategy was first approached by Mahapatra et al. In this small study (n = 20 patients), the investigators identified a signature pressure frequency to enable easy recognition of the pericardial space and help guide access. In order to record the pressure inside the pericardium and pleural space, a 10-Fr long sheath was used. Pressures were evaluated using a fast Fourier transform to establish dominant frequencies in each chamber. The pericardium and the pleural space had very similar mean pressures (7.8 ± 0.9 mmHg vs. 7.7 ± 1.9 mmHg, respectively). Nevertheless, the pericardial space in each patient revealed two frequency peaks corresponding to both heart rate (1.16 ± 0.21 Hz) and respiratory rate (0.20 ± 0.01 Hz), while the pleural space had a single peak correlating with respiratory rate (0.20 ± 0.01 Hz).¹⁰ This finding represented the key principle, which facilitated the development of a novel access needles in order to decrease complications from epicardial access procedures.

Based on the high risk of inadvertent right ventricle (RV) puncture and the initial findings of Mahapatra et al., a novel technique for epicardial access emerged: the EpiAccess System (EpiEP, Inc., New Haven, CT).

NEEDLE DESCRIPTION

Briefly, the EpiAccess System consists of an apparatus that enables the use of the Tuohy needle along with a sensor that displays the pressure waveform, allowing electrophysiologists to confirm the location of the needle in the pericardial sac in real time. The EpiAccess System has the following key components: access needle with a fiberoptic pressure frequency sensor encased in a stainless steel tube (Figure 5.1) and a monitor with a patent software that captures the real-time pressure frequency signal from the sensor (Figure 5.2) and delivers it to a computer with a graphical user interface (Figure 5.3). The way pressure and frequency data are displayed helps in the positioning of the needle adjunctive to fluoroscopic imaging.

Figure 5.1 EpiAccess needle. The needle has a pressure frequency fiberoptic sensor contained within a stainless steel tube welded inside the lumen of the cannula and a monitor with a software that displays the real-time pressure frequency signal from the sensor.

Figure 5.2 Diagram showing the sensor at the tip of the EpiAccess needle. The EpiAccess needle has a fiberoptic sensor that transmits the pressure frequency measurements at the tip of the needle. The sensor is accessible to detect pressure frequency based on the concept of a Fabry-Perot interferometry, where the transducer membrane deflects under pressure as the needle traverses different media.

Figure 5.3 EpiAccess monitor displays the arterial blood pressure and the pressure at the tip of the needle. This tracing shows the change in needle-tip pressure once the pericardial space has been touched. An algorithm conducts a beat-to-beat evaluation of the needle-tip pressure frequency using the arterial pressure signal as a gate and graphs the pulsatility pattern within the needle-tip pressure signal.

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