Transcatheter closure of patent foramen ovale (PFO) has recently gained acceptance as a form of therapy for patients with cryptogenic stroke.1–3 The standard approach involves passage of a large delivery sheath from the femoral vein into the inferior vena cava and right atrium. The delivery sheath is then positioned across the PFO, and the septal occlusion device is deployed under both fluoroscopic and transesophageal echo (TEE) guidance. The approach as previously described is often straightforward; however, previous placement of an inferior vena cava (IVC) filter can preclude the performance of right heart catheterization through the femoral venous system, for fear of dislodging the IVC filter.4,5 We describe a novel approach to prevent or minimize the risk of displacement/dislodgement of a previously implanted IVC filter in a patient with cryptogenic stroke who underwent transcatheter closure of a PFO. Case Report. A 36-year-old woman previously diagnosed with multiple cerebellar infarcts and possible pulmonary embolism and who had prior placement of an IVC filter (Greenfield Filter) was referred for transcatheter closure of patent foramen ovale. The patient had previously undergone work-up to rule out the presence of a hypercoagulable state. Transesophageal echocardiography demonstrated the presence of paradoxical (right to left) flow across the PFO. After discussing the risks and benefits of cardiac catheterization and transcatheter closure of PFO, consent was obtained and the decision was made to proceed with cardiac catheterization. A 7 French (Fr) sheath was positioned in the right femoral vein and a 4 Fr sheath was positioned in the left femoral artery (to monitor arterial blood pressure). After obtaining both venous and arterial access, the patient received a 3,000 unit bolus of heparin. Angiography was then performed through a 7 Fr NIH Cardiomarker catheter (Medtronic AVE, Santa Rosa, California) positioned in the inferior vena cava directly below the Greenfield filter (Meditech, Watertown, Massachusetts) (Figure 1). Angiography was performed in the IVC to make sure that there was no clot or thrombus present in either the IVC or the Greenfield filter. The Cardiomarker catheter was then exchanged for a 7 Fr Goodale Lubin (GL) end-hole catheter (Medtronic AVE), which was positioned directly below the IVC filter. A 0.035´´ Amplatz super-stiff guidewire with a 1 cm, soft straight tip (Boston Scientific/Scimed, Inc., Maple Grove, Minnesota) was then advanced through the GL catheter and across the IVC filter into the right atrium. Both the GL catheter and 7 Fr sheath were then removed and exchanged over the super-stiff wire for a 10 Fr Mullins transseptal sheath (Cook Incorporated, Bloomington, Indiana). Under both PA and lateral fluoroscopy, the transseptal sheath (TSS) was carefully advanced over the super-stiff wire through the IVC filter. The TSS was then positioned in the IVC/right atrial junction. The dilator and super-stiff wire were then slowly withdrawn and the sheath was bled back to clear it of any bubbles. A slow flush was then attached to the back-bleed device at the end of the TSS. A 7 Fr Multipurpose (MP) catheter (Cordis Corporation, Miami Lakes, Florida) was then advanced through the transseptal sheath positioned in the IVC/right atrial junction. Right heart catheterization was performed, after which agitated saline was injected through the MP catheter in the right atrium to demonstrate paradoxical right to left flow [demonstrated by transesophageal echocardiography (TEE)]. The MP catheter was advanced across the patent foramen ovale into the left atrium. Left atrial pressure and saturation measurements where then obtained. The PA camera was positioned in left anterior oblique/cranial angulation, and left atrial angiography was performed (Figure 2). The MP catheter was then positioned in the left upper pulmonary vein. A 0.035´´ Amplatz super-stiff wire was advanced through the MP catheter into the left upper pulmonary vein. The MP catheter was then exchanged over the super-stiff wire for a 20 mm NuMED sizing balloon (NuMED, Hopkinton, New York). Balloon sizing of the PFO was performed. The PFO was measured both fluoroscopically and by TEE. The sizing balloon was removed over the super-stiff wire and the TSS was then bled back to clear it of any bubbles. After making sure that the sheath was adequately flushed, the TSS was advanced over the super-stiff wire into the left atrium. After confirming proper position of the TSS in the left atrium, the super-stiff wire was removed. A 28 mm CardioSeal septal occlusion device (NMT Medical, Boston, Massachusetts) was then safely deployed across the atrial septum (Figure 3). The TSS was positioned in the IVC/RA junction. The delivery catheter was then removed from the TSS, bled back and cleared of bubbles. The 7 Fr MP catheter was advanced through the TSS and positioned in the right atrium. Repeat bubble study through the MP catheter was then performed, confirming complete occlusion of the foramen ovale (absence of paradoxical flow by TEE evaluation). The MP catheter was removed and exchanged for the super-stiff wire, which was positioned in the IVC/RA junction. The TSS was then carefully withdrawn over the super-stiff wire under fluoroscopic guidance. The super-stiff wire was carefully withdrawn out of the body under fluoroscopic guidance. Discussion. In the past, the presence of an IVC filter was considered a contraindication to the performance of right heart catheterization from the femoral venous system. Patients who had prior placement of an IVC filter could, however, undergo right heart catheterization through the internal jugular veins, subclavian veins or via the transhepatic approach. Recent reports have shown that right heart catheterization through a previously implanted IVC filter is technically feasible and can be safely performed without complications.6 We describe a technique that allows for the performance of both right heart catheterization and device closure of a PFO through a previously implanted IVC filter. The technique described is able to minimize displacement of the previously implanted IVC filter by limiting the number of catheter and sheath exchanges through the previously implanted IVC filter. Utilizing this technique, the IVC filter is only traversed once with the TSS. Once the TSS is positioned in the IVC/RA junction, right heart catheterization, angiography, balloon sizing of the PFO and device deployment can be safely performed with the appropriate catheters through the TSS. There are several important technical points. The performance of angiography in the IVC prior to passage of a guidewire or catheter is important to make sure that there are no clots or thrombi that could be dislodged during guidewire or sheath advancement through the IVC filter. The use of a straight guidewire to traverse the Greenfield filter is also important. There have been previous reports of J-tipped guidewires becoming trapped within the arms of the Greenfield filter.4,5 The choice of wire is important because it must also be stiff enough so that the natural curve of the TSS does not distort the arms of the Greenfield filter as it is advanced into the IVC/RA junction. This is true for both the initial phase of the catheterization when the IVC filter is first traversed and at the end of the case when it is time to remove the TSS. Both PA and lateral fluoroscopy are essential so that the operator can follow the course of both the guidewire and TSS as they are advanced (initially) and withdrawn (at the end of the case) through the IVC filter. Because of the length of the TSS, it is absolutely essential to clear the sheath of any bubbles that might be trapped within the sheath. This must be performed after each catheter exchange to prevent trapping of air bubbles or clot formation within the sheath. We have also found it beneficial to attach a slow, continuous heparinized flush to the back-bleed device at the end of the sheath prior to the introduction of any catheter or device into the sheath. This is important because catheter and sheath mismatch can lead to clot formation within the TSS. The device used to close the PFO in this patient was a CardioSeal septal occlusion device. As of this writing, this is the only Food and Drug Administration (FDA)-approved device for PFO closure in the US. In the past, this device could only be delivered through an 11 or 12 Fr sheath. Since the redesign of its loading mechanism, the device can now be delivered through a 10 Fr sheath. While this is an improvement compared to the earlier design, it still requires a relatively large sheath when compared to some of the newer septal occlusion devices (Amplatzer, Helex, etc.), which can be delivered through smaller sheaths. Because these newer devices can be delivered through smaller sheaths, traversing previously implanted IVC filters could be potentially safer. Another alternative would have been to obtain transhepatic access. The transhepatic approach has previously been described to close atrial septal defects and perform other interventional procedures;7 however, this approach is not without risk, and intraperitoneal hemorrhage has been described.8 In the future, once the other septal occlusion devices that use smaller delivery sheaths receive FDA approval for PFO closure, the transhepatic approach may become a safer option. In the interim, if one utilizes the aforementioned technique, the performance of cardiac catheterization, angiography, balloon sizing and device closure of PFO can be performed with minimal risk of dislodgement of the IVC filter. In summary, we describe a novel technique to prevent displacement of a previously implanted IVC filter in a patient with cryptogenic stroke who underwent transcatheter closure of a patent foramen ovale. We believe that this technique can minimize the number of catheters/sheaths that need to traverse the IVC filter, thereby decreasing the risk of displacement/dislodgement of the IVC filter.
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