INTRODUCTION

Percutaneous epicardial access is now widely used to mapping and ablation for ventricular tachycardia (VT), especially in idiopathic dilated cardiomyopathy, arrhythmogenic right ventricular dysplasia, sarcoidosis, and Brugada syndrome. It is increasingly used in ischemic VT substrates and, occasionally, epicardial atrioventricular accessory pathways. The ability to access the pericardium also offers the potential for alternative means of ablation of atrial fibrillation, esophageal protection during endocardial atrial fibrillation, for targeting epicardial structures during atrial fibrillation ablation, phrenic nerve protection in ventricular or atrial tachycardias, and for left atrial appendage closure.

Since Sosa and colleagues described the use of an 18-gauge Tuohy needle for entering epicardial space,¹ efforts have been made to improve the safety and ease of epicardial access. One such technique is the use of a micropuncture, “needle-in-needle” approach.^2,3 This chapter will describe the rationale for micropuncture access, outline the technical aspects of the micropuncture needle-in-needle approach, and describe outcomes of this approach, as published in the literature.

RATIONALE FOR MICROPUNCTURE ACCESS

The traditional method of epicardial access, described in the previous chapter, uses an 18-gauge, 6-inch Tuohy needle (Figure 4.1). This needle has a side-facing, bevelled lumen that facilitates access to potential spaces, such as the epidural space. A subxiphoid percutaneous approach is used, similar to the traditional subxiphoid access used for pericardiocentesis. During routine pericardiocentesis, a supraphysiological volume of pericardial fluid expands the pericardial space and provides a buffer between the parietal and visceral pericardium protecting the heart from injury. In comparison, only the physiologic amount of serous fluid (20 to 60 mL) that lubricates the movement of the visceral on parietal pericardium is present during epicardial access. Consequently, the feared complication of access into this dry space is puncture or laceration of the right ventricle or coronary arteries causing hemopericardium and/or cardiac tamponade.

Figure 4.1 Tools for epicardial access. Panel A: Standard 18-gauge Tuohy needle with bevelled edge. Panel B: Green 21-gauge micropuncture (MP) needle, which can be inserted inside the pink 18-gauge guiding Cook needle. (Figure 4.1, Panel B obtained from Kumar et al., with permission.)

The gauge of the needle used is an important consideration when obtaining epicardial access. In theory, compared to a smaller needle, a larger-bore needle will require higher force to penetrate the tough parietal pericardium. When the parietal pericardium gives way, the forward force may propel the needle into contact with the epicardial surface. In addition, with cardiac and respiratory motion present as the needle is moving forward with force, there may be higher shearing force that could result in a laceration rather than a simple puncture. Compared to the traditionally used 18-gauge needle, a 21-gauge micropuncture needle has 58% less surface area and hence exerts less shearing force as it enters the pericardium (Table 4.1).

Table 4.1 Comparison of 18-Gauge Tuohy and 21-Gauge Micropuncture Needle Sizes

Studies have demonstrated a substantial risk of right ventricular puncture with standard percutaneous epicardial access approaches, which can occur in 17% of cases.⁴ Despite this relatively high rate of injury, only 3.5% to 5% of patients develop major epicardial bleeding.^4,5 This difference may be due to “auto-seal” of the puncture site.² We suggest that inadvertent myocardial puncture with a smaller-bore micropuncture needle, compared to relatively larger-bore needles, will cause less injury and allow more opportunity for an auto-seal to form without hemodynamically significant bleeding.

TECHNIQUE OF NEEDLE-IN-NEEDLE MICROPUNCTURE EPICARDIAL ACCESS

We found that there is a tendency for a long 21-gauge micropuncture needle to flex during the course of insertion through the tissue beneath the sternum as it approaches the pericardium. This made it difficult to maintain the needle on a straight path, crucial for safe epicardial access. Additionally, tactile perception of force and cardiac motion was also limited. To improve control and tactile feel with the micropuncture needle, a “needle-in-needle” approach was developed.³

In this method, an 18-gauge Cook needle (percutaneous entry thin wall needle, 18-gauge, 7 cm, Cook Medical, Bloomington, IN) is inserted in the subxiphoid space well outside the pericardium. Subsequently either a 21-gauge micropuncture needle (Cook medical) or 21-gauge long spinal needle (Chiba Biopsy needle, Cook Medical) is inserted to telescope through the larger needle. This improves the stability of the micropuncture needle and the tactile feedback. The technique is an extension of the Sosa technique with some important variations.

Step 1: Insertion of the Cook Needle

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