Different Ways of Aproaching the Normal Pericardial Space
To the Editor:
We have read with great interest the article by Verrier et al1 on transatrial access to the pericardial space, surely an attractive idea. Exploration of the pericardial space has long been a medical challenge, because it has been suggested that pericardial puncture could only be possible in the presence of a sizable pericardial effusion. However, this concept should no longer be sustained as a definite fact. It is clear from our clinical experience that entering the pericardial space does not require the presence of 200 mL of pericardial fluid, as stated by the authors.
In 1996, our group introduced a novel nonsurgical transthoracic technique to perform epicardial mapping and ablation in the electrophysiology laboratory.2 3 4 It consists of the introduction of a regular ablation catheter into the pericardial space by a transthoracic pericardial puncture similar to that described by Krikorian and Hancock.5 The main difference is that our patients do not have pericardial effusions.
According to our technique, pericardial puncture is performed via a subxiphoid approach. An epidural needle (Tuohy 17 gauge, effective length 79.4 mm, overall 101.6 mm, OD 1.5 mm; Abbott) used to perform epidural anesthesia is gently advanced under fluoroscopy toward the cardiac silhouette until a slight negative pressure is felt. When the needle tip is inside the pericardial space, contrast medium is injected, which can be seen surrounding the cardiac silhouette, indicating that the needle tip is in the pericardial space. Then, a soft, floppy-tip guidewire is passed through the hollow needle, an 8F introducer is advanced into the pericardial space, and the guidewire is removed. Finally, a 7F catheter is introduced into the pericardial space. As electrophysiologists, our purpose is to perform epicardial mapping and ablation with this technique. However, the technique could be used for the same objectives proposed by Verrier et al.1
Thus far, the transthoracic approach to the pericardial space has been used in 42 patients. Echocardiograms obtained in each patient 1 week after the procedure showed no effusion. No long-term follow-up complications were detected. Three patients complained of mild chest pain, which was controlled with regular anti-inflammatory drugs. Because Verrier et al1 reported that only 2 dogs were observed for 24 hours, more information is necessary on survival studies before transatrial access is clinically admissible.
- Copyright © 1999 by American Heart Association
We appreciate Drs Sosa, Scanavacca, and d’Avila’s interest in our recent article.R1 There, we stated that the subxiphoid method generally requires the presence of substantial (>200 mL) pericardial fluid to minimize the risk of coronary laceration and myocardial puncture. Dr Sosa and colleagues cite their own recent experience to suggest that the pericardial space may be safely accessed by the subxiphoid route in patients who do not have effusion. This claim is based on 42 patients who had undergone this procedure for epicardial mapping and ablation.
Since Dr Sosa and colleagues appear to use components and methods that are standard in the subxiphoid approach for pericardiocentesis, it implies that their success may relate in part to their extensive experience and skill. However, it is noted that even in their hands (their Reference 3), 1 of 10 patients experienced hemopericardium requiring drainage. In their letter, no comment is made regarding this or other acute complications of transthoracic pericardial access.
We have simplified our technique, now introducing only a 0.038-in infusion wire across the atrial wall and obviating the need for the needle catheter, and have significantly extended our experience with an additional 20 large animals, demonstrating the safety of this approach at 24 hours and 2 weeks after the procedure.R2 There were no hemodynamic or ECG changes during or after the procedure, and there was no evidence of fluid accumulation or hemopericardium at either period. In 6 additional pigs, we found that aspirin use was not associated with increased risk (unpublished data). Pericardial access was successful in all attempts, was obtained within 3 to 5 minutes after right heart catheterization, and did not require injection of contrast material.
From a broader perspective, the development of these methods, with their relative advantages and disadvantages, serves an important goal of drawing attention to the potential opportunities of using the pericardial space for diagnostic sampling and therapeutic interventions. Indeed, there is mounting evidence to support this concept, as experimental studies of intrapericardial therapy have demonstrated salvage of infarcted myocardium and treatment of ischemia by angiogenesis,R3 inhibition of restenosis,R4 and antiarrhythmic action.R5
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Waxman S, Pulerwitz TC, Rowe KA, Quist WC, Verrier RL. Preclinical safety testing of percutaneous transatrial access to the normal pericardial space for local cardiac drug delivery and diagnostic sampling. Catheter Cardiovasc Interv. In press.
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