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Closure of the Patent Foramen Ovale

The End of the Sound and Vision Era Approaching^_*

Cardiovascular Department, University Hospital, Bern, Switzerland.

Key Words: patent foramen ovale closure • intracardiac echocardiography • percutaneous closure • transesophageal echocardiography

The act of percutaneously closing a patent foramen ovale (PFO) may be accomplished in as little as 10 min from the needle puncture of the femoral vein to the patient putting his finger on the groin while the sheath is removed and then walking out of the catheterization laboratory, as would happen after donating a pint of blood at a Red Cross station. Complications are exceedingly rare with the belt (fluoroscopy) alone (1–3). The paper of Hildick-Smith et al. (4) in this issue of JACC: Cardiovascular Interventions deals with the question whether and when suspenders (echocardiographic guidance) might still be needed or recommended. And then again, it does not. It convincingly shows that, in the majority of consecutive patients, the omission of ultrasound guidance did not impair the result of PFO closure. However, it does not provide evidence about whether ultrasound guidance did improve the results in the minority in whom it was used.

Arguments in favor or disfavor of using intraoperative ultrasound during PFO closures are depicted in Table 1. Although not all of the arguments in favor can be discarded lightly, it can be foretold that the more common PFO closure will become, the more the procedure will have to be simplified. The risk of suboptimal placement or device embolization is extremely small if the fluoroscopic assessment is exploited in the correct projection using contrast medium (Fig. 1).

View larger version (76K): [in this window] [in a new window] [Download PPT slide]   Figure 1 Angiographic Aspect of a 25-mm Amplatzer PFO Occluder Before and After Release Provided a correct view is chosen depicting the 2 disks in perfect profile without any overlap (usually a left oblique projection with cranial tilt), the correct position of the device can be unequivocally ascertained before (left) and documented after (right) release. The left halves of the disks are separated by the muscular septum secundum (SS), whereas the septum primum (SP) is thin, wraps around the inferior rim of the device before release (device position tilted by the stiff pusher cable), and extends from the lower rim after release. The dashed arrow indicates the actual PFO tunnel. The fact that the interdisk connector is not passing the PFO at its very top (top of arrow) is explained by the fact that the PFO slit has to be pictured as a sad mouth with a device connector typically hanging low in either mouth angle. PFO = patent foramen ovale.

The use of a few milliliters of contrast medium should not pose a problem in any patient. A rare circumstance, such as an urgent need for PFO closure in early pregnancy, may impose PFO closure exclusively (5) or almost exclusively (6) guided by ultrasound.

The sharing of responsibility at the crucial moment of device release from the implantation gear is an important feature in the beginning of the learning curve of an operator. However, the second opinion from the echocardiographer is of little value, if he or she is also inexperienced, which is usually the case in an institution embarking on PFO closure. For a rookie operator in an experienced institution, the advice of a PFO-savvy interventional cardiologist is usually available.

The arguments against using ultrasound guidance appear more compelling. To avoid undue inconvenience and risk to the patient, intubation and general anesthesia is usually considered a prerequisite for TEE guidance. This more than triples the time of the intervention and generally requires a third physician in addition to the echocardiographer. Using TEE under simple sedation and local anesthesia is overshadowed by the risk of bronchial aspiration of saliva due to the patient being in the supine position.

The use of intracardiac echocardiography (ICE) also prolongs the procedure significantly but it does not necessarily require an additional physician. However, introducing the ICE probe (not wire-guided) is a fairly rough act with at least a doubled risk of puncture site problems and cardiac perforation. A single operator gets distracted by trying to keep the ICE probe properly directed while also handling the device closure equipment. Moreover, the additional expense of approximately U.S. $2,000 is to be considered.

There are 2 major prerequisites to turn PFO closure into what could come close to a mechanical vaccination acceptable for all people with a PFO (approximately 25% of the general population) or at least those with a dangerous variation of it (approximately 4%), in whom the 2 septa are barely touching and the septum primum is extremely mobile and flimsy, which is usually referred to as atrial septal aneurysm.

First, it has to be efficient and safe. A complete closure rate of 100% will never be achieved but, with the current technology of choice (3), a significant and "unfiltered" (unimpeded by the implanted device) residual shunt persists in <5% of patients. A second device can remedy those 5% with a second intervention even more swiftly than the initial one. Safety is at least comparable with what is usually accepted for a vaccine. The only procedure complication, occurring at a rate approaching 1%, is an arteriovenous fistula at the groin. This is clinically benign but may need local surgery. The dreaded bacterial infection of the device has been reported, but only in a couple of isolated cases in the world literature. Even assuming underreporting, these cases have to be seen against the background of devices having been implanted for PFO closure worldwide in more than 100,000 people. The same holds true for erosion of a free atrial wall by the device. This has been reported in only 2 of more than 50,000 people having been fitted with an Amplatzer PFO occluder (AGA Medical, North Plymouth, Minnesota). Such an incidence of an admittedly severe side effect is indeed comparable with the severe side effects of recommended vaccinations against childhood diseases. The second prerequisite is that the intervention is simple and this forfeits the use of ultrasound guidance.

Before we can convince people that the general population might need vaccination against a disease, they have to be convinced that the disease needs prevention. The current misclassification of strokes mediated by the PFO as an entity only to be considered after excluding all other ischemic stroke causes (after the establishment of the diagnosis of cryptogenic [unexplained] stroke) needs to be revised. The PFO can be the cause of an ischemic stroke with and without the presence of other acknowledged ischemic stroke reasons (Table 2). The term cryptogenic has to be pushed beyond the PFO and perhaps even beyond the embolism from a clot originating form the pulmonary venous bed, a mystic medical black box, the discussion of which is beyond the scope of these remarks.

	Footnotes

 
Dr. Meier has received research grants and is on the Speakers' Bureau of AGA Medical.

^_* Editorials published in JACC: Cardiovascular Interventions reflect the views of the authors and do not necessarily represent the views of JACC: Cardiovascular Intervention or the American College of Cardiology.

^_* Reprint requests and correspondence: Dr. Bernhard Meier, Professor and Chairman of Cardiology, Cardiovascular Department, University Hospital, 3010 Bern, Switzerland. (Email: bernhard.meier{at}insel.ch).

	REFERENCES

Top REFERENCES

 

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3. Wahl A, Praz F, Stirnimann J, et al. Safety and feasibility of percutaneous closure of patent foramen ovale without intra-procedural echocardiography in 825 patients. Swiss Med Wkly. In Press.
4. Hildick-Smith D, Behan M, Haworth P, Rana B, Thomas M. Patent foramen ovale closure without echocardiographic control: use of "standby" intracardiac ultrasound J Am Coll Cardiol Intv 2008;1:387-391.[Abstract/Free Full Text]
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This article has been cited by other articles:

				J. D. Newton, A. R.J. Mitchell, N. Wilson, and O. J. Ormerod Intracardiac Echocardiography for Patent Foramen Ovale Closure: Justification of Routine Use J. Am. Coll. Cardiol. Intv., April 1, 2009; 2(4): 369 - 369. [Full Text] [PDF]

				B. Meier Reply J. Am. Coll. Cardiol. Intv., April 1, 2009; 2(4): 369 - 370. [Full Text] [PDF]

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