CHAPTER 28 Atrial septal defect occlusion 749 When satisfied with the configuration and the position on the septum by both fluoroscopy and by TEE or ICE, the security of the fixation in the septum is “tested” by means of a moderately vigorous, to and fro, push–pull on the delivery cable/devicea the so called “Minnesota wiggle”. When both disks are positioned properly on and fixed securely in the septum and as traction is applied to the cable and the device, which is fixed securely in the sep- tum, the right and left atrial disks separate from each other with each pull. As the disks are separated, the rim of septal tissue that is between the disks is seen even more clearly on the TEE or ICE. As the cable is pushed during the “wiggle”, the right and left atrial disks are pushed together, but still should have some distance between the opposing edges of the disks and should not push through and/or away from the septal defect. The entire circumfer- ence of the device is scrutinized with the TEE or ICE during the “wiggle” to verify that the septal rim is “sand- wiched” between the two disks all of the way round the device. A small hand angiogram, with an injection through the separate catheter positioned close to or against the right sided disk of the device demonstrates the alignment of the device relative to the septum and helps to demonstrate if part of either disk is on the wrong side of the septum. Rarely, as the left atrial disk and the central hub are extruded from the sheath, the left atrial side does not form a “disk”, but rather extrudes in an elongated, spiral or “cobra” configuration. This abnormal configuration usu- ally persists even after the hub and right disk are com- pletely out of the delivery sheath. The exact etiology of this deformation probably is related to how the “wires” of the Nitinol™ weave expand from their elongated configuration relative to each other and/or may be related to excessive torquing of the device and cable while they were still within the sheath. Usually patience is all that is necessary and the device gradually resumes its normal configuration. If the abnormal configuration persists, the device and sheath are moved forward slightly and/or the device is withdrawn into the sheath and the deployment repeated. Rarely, even with repeated withdrawal and redeployment, the deformity persists. In that case the sheath is advanced back into the left atrium over the device and the device is withdrawn out of the body. If the device still has the deformed configuration after it is withdrawn from the sheath, the device is manually elon- gated by traction on both hubs and then released to allow it to re-form its “resting”, flat configuration. In this oper- ator’s experience, the device always has resumed its nor- mal configuration with this maneuver outside of the body. Once it returns to its normal shape, the same device can be reloaded and redeployed successfully. A major advantage of the Amplatzer™ ASD device is that any time before it is released purposefully, it very easily can be withdrawn back into the delivery sheath. If the device is not sized accurately, if it is malpositioned in the defect, or if it pulls through the defect at any stage of the delivery, the device easily can be withdrawn back into the sheath. The sheath then can be repositioned through the defect where the same device can be reimplanted or the original device is removed completely and a new device delivered through the same sheath. If necessary for any reason, the withdrawal into the sheath and redeployment can be accomplished multiple times. However, the more times a device is pulled into the sheath and redeployed, the more likely the sheath is to be distorted, the delivery cable unwound from the device and/or the device dis- torted permanently. Once the device is fixed securely within the septum with a satisfactory position of the device in the septal defect and there is no significant residual leak, the device/cable is prepared for release. The torquing hub is attached firmly to the proximal end of the delivery cable by introducing the end of the delivery cable as far as pos- sible into the open hole in the torquing hub, and then tightening the small set screw that is on the side of the torquing hub onto the cable. The device is uncoupled from the delivery cable by many, rapid, counterclockwise turns of the delivery cable using the torquing device. It usually takes 6 to 7 complete counterclockwise turns of the cable to unscrew the delivery cable from the proximal hub of the device. During all of the time when the device is being unscrewed, the device/cable should be observed on fluoroscopy or, preferably, recorded on biplane stored fluoroscopy to be sure that the device is not bound abnor- mally to the cable and/or is not being distorted in the septum during the unscrewing process. As the device unscrews completely and becomes free of the cable, it usu- ally moves away from the cable and realigns its position significantly, as it reorients itself more properly into the plane of the septum (Figure 28.11). This movement can be quite extensive and sudden. After the device is released and reoriented on the septum, the position of the device and the presence of any residual leaks are scrutinized by TEE or ICE. In order to offset the pressure effects of the shunt vol- ume, which has become “trapped” suddenly in the left heart (and left atrium in particular) and until the total cir- culation has had time to “redistribute this volume”, patients with very large defects and/or minimal circum- ferential rims are given 0.25–0.5 mg/kg of furosemide intravenously immediately prior to the implant of the device. The heparin given during the case is not reversed at the end of the case. All patients are given an intra- venous dose of a cephalosporin at the time of the implant of the device and two or three more intravenous doses at intervals of 6 or 8 hours before discharge from the CHAPTER 28 Atrial septal defect occlusion 750 hospital. The patients are discharged on aspirin, 81 mg/day, which is to be continued for 6 months and with instruc- tions to utilize bacterial endocarditis prophylaxis at times of high risk to bacteremia during that same 6 months. In the United States, the Amplatzer ASD™ device underwent a regulated FDA, IDE clinical trial and com- pleted a one-year follow-up of the implanted devices in early 2001. The Amplatzer™ ASD occlusion devices received FDA approval for the elective transcatheter occlusion of the secundum ASD in the US in September of 2001, and the final notification of approval was received in December 2001. This is the first implantable intracar- diac device ever approved by the FDA for elective clinical use specifically in a congenital heart lesion and in pedi- atric patients. Excessive Eustachian valve and the Amplatzer™ device Although the Amplatzer™ ASD device has no legs that can spring open into the right atrium and that, in turn, could catch on a redundant Eustachian valve, there still are potential problems with the delivery of the Amplatzer™ ASD devices in the presence of excessive Eustachian valve tissue. The redundant Eustachian valve tissue usually is seen as a very flexible structure, which flops in and out of the echo field adjacent to the atrial sep- tum and atrial septal defect. The most common problem with the Amplatzer™ ASD device and the Eustachian tissues occurs as the delivery cable is being unscrewed during the release of the cable from the device. The mod- erately rough surface of the rotating, exposed cable can tangle with the Eustachian tissue and, when it does, it winds the redundant tissue around the delivery cable. When the cable becomes entangled during the release of the device, the Eustachian tissue sometimes can be untangled by rotating the cable in a clockwise direction after the release of the device, although this can wind the Eustachian tissue even tighter around the cable and wind it in both directions. When the Eustachian tissue becomes entangled around the cable, the sheath is advanced over the cable and the cable is withdrawn forcefully into the delivery sheath along with part of the Eustachian valve. As with most complications, prevention of the problem is preferable. When the Eustachian tissue is noticed in close proximity to the device and cable and after the secure deployment of the device, the long sheath is re-advanced carefully over the cable and back against the surface of the right atrial disk before the cable is unscrewed from the device. The sheath covers the cable, “separates” the rotat- ing cable from the Eustachian valve tissues and prevents cable entrapment. Very extensive, redundant Eustachian tissue also can become entangled in the mesh of the central hub and/or proximal (right atrial) disk of the device, particularly as the device is rotated and/or as the open mesh of the right atrial disk is extruded. If the Eustachian tissue remains entangled on the device and is unrecognized, it creates a partial “diaphragm” across the entrance of the inferior vena cava. The amount of obstruction from this tissue depends upon the density and extent of the Eustachian tissue. When the Eustachian tissue remains attached to the device after the release of the device, the entangled Eustachian tissue can be separated from the device using a large angioplasty or static sizing balloon. The balloon catheter is maneuvered between the Eustachian tissue and device using TEE or ICE guidance and once positioned between the tissues, the balloon is inflated. This maneu- ver may have to be repeated several times to free the Figure 28.11 Amplatzer™ ASD device fully deployed and released. Torsion from cable is released. Device flattens and aligns exactly on septum with the central hub opened fully and fixing the device in the septal defect. CHAPTER 28 Atrial septal defect occlusion 751 Eustachian tissues totally. It always is prudent to avoid the entanglement when Eustachian tissue is present. In every case of a potential occlusion of an ASD with a catheter-delivered device, the right atrium should be scrutinized thoroughly for long and/or redundant Eustachian valve tissue by TEE or ICE. When encoun- tered, the Eustachian valve tissue can be trapped and “moved away” from the defect with a deflector catheter as described later in this chapter in the discussion of the CardioSEAL™ and STARFlex™ devices, where the Eustachian valve is even more of a problem. Retrieval of the Amplatzer™ ASD device One of the major advantages of the Amplatzer ASD Device™ is the ability to be withdrawn back into the delivery sheath, easily, and at any time, before the purpose- ful release of the device from the delivery cable. This withdrawal back into the sheath and redeployment of the device can be repeated many times if necessary. This of course holds true, not only for repositioning the device on the septum, but for removing the device completely if a perfect implant on the septum is not achieved or if the device pulls completely through the septum. The with- drawal is accomplished by placing tension on the delivery cable while the sheath is advanced simultaneously over the device and while withdrawing the device. These maneuvers re-elongate the device similar to the procedure for its loading. Occasionally, the distal end of the delivery sheath becomes distorted (accordioned) with repeated with- drawal and redeployment of the device and eventually even the still attached, but deployed and malpositioned Amplatzer™ device cannot be withdrawn into the ori- ginal, distorted sheath. The Amplatzer™ system has a unique recovery wire/sheath/dilator exchange system for just such an occurrence. The proximal end of every standard Amplatzer™ delivery cable has a small hub with a female screw socket in the hub, which is identical to the socket in the hub on the device. This screw socket allows a second delivery cable to be attached to the proximal end of the original cable, which, in turn, produces an “exchange length” delivery cable! The dilator of the recovery sheath/ dilator has an extra large lumen and distal opening, which accommodates the diameter of the delivery cable. The “exchange length” cable allows the original dam- aged sheath to be withdrawn over the “exchange cable” and completely out of the body while the device still is open and attached to the original part of the cable within the heart. Once the damaged sheath is removed, the “recovery” sheath/dilator with the larger lumen of the special dilator is advanced over the “exchange cable” to a position adjacent to the still attached device. The dilator is removed from the new sheath over the cable and the system is cleared meticulously of air and/or clot by allow- ing free back-flow from the sheath. The back-bleed/flush valve is reintroduced over the “exchange” cable, attached to the new sheath and the system is flushed. With the new sheath in place, the still attached Amplatzer™ occlusion device is readily withdrawn into the new, undamaged sheath. Once the device has been released from the cable, retrieval of the Amplatzer™ device still is possible, but not as easily, nor as predictably, as before its release 15 . The possibility of a device embolization should always be included in the “pre-catheterization” discussion with the patient/parents. Along with the potential for emboliza- tion, the possible need for surgical retrieval should always be presented to the patient/parents. The key element to retrieval of an embolized Amplatzer™ ASD occluder is to re-catch the device by the central metal attachment “post” on the right atrial disk of the device. This is accomplished using a 10 mm Microvena™ snare and snare catheter passed through a very large diameter long sheath. The long sheath that is used for the retrieval of an Amplatzer™ ASD occluder should be at least two French sizes larger than the original delivery sheath and the retrieval sheath should be as stiff as pos- sible. A long sheath that is even larger than two French sizes larger than the original delivery sheath is even more advantageous. If the fully released device is not still on the septum or, at least, is not in an orientation within the heart and/or great artery with the right atrial “hub” facing the retrieval catheter, the errant device must be reoriented in the vessel or chamber using another catheter and/or wire in order to make the central “post” accessible to the loop of the snare. This reorientation is performed with a separate catheter, often approaching the device from the superior vena cava or even an artery when the device is lodged on the left side of the septum. The orientation of the device can be changed using an active deflector wire and/or a bioptome forceps to grasp an edge of the device in order to turn and/or hold it while the right sided post is grasped by the snare, which has been introduced through the large, long recovery sheath. Once the device has been turned to an appropriate orientation, it is helpful to “impale” the device with a straight, stiff, guide wire passed through and through the mesh of the device in order to fix the device in the particular more favorable location and orientation. When an Amplatzer™ atrial septal occluder has embolized into, or is lodged in, either ventricle, a very gentle attempt is made to grasp any part of the device with a bioptome in order to withdraw the device out of the ven- tricle with “teasing” maneuvers. Absolutely no force must be used in this attempt. If the device cannot be withdrawn gently through the atrioventricular valve, it may be pos- sible to manipulate it in the ventricle until it moves through, CHAPTER 28 Atrial septal defect occlusion 752 or can be drawn through, the semilunar valve and into the great vessel off the ventricle. In the great artery the device still must be turned/reoriented until the right- sided “post” is accessible to the snare catheter and the long sheath. The ASD occluder always should be with- drawn into the long sheath before attempting to withdraw it through a ventricle. Once the metal post has been grasped securely with the snare, the device is withdrawn to the tip of the long sheath and withdrawn into the sheath. When the snare loop tightens on the attachment post of the device, the central “post” on the device becomes positioned next to, and par- allel to the tip of the snare catheter. This creates a distinct “offset” of the small hub (post) on the device next to the tip of the snare catheter. This small offset frequently requires significant extra manipulations of the snare catheter and sheath together in order to maneuver the “shelf” created by the offset of the snare along with the grasped “post” of the device into the sheath. Making a small longitudinal slit in the tip of the long sheath before its introduction into the body has been suggested as beneficial for this maneuver. Occasionally, because of a curve on the sheath and/or the curved course through the body to approach the errant device, the grasped, offset post on the device cannot be centered enough to be withdrawn into the sheath alone even with very extensive manipulations. When this prob- lem is anticipated, it is avoided by first introducing the snare catheter into and through the dilator of the new large, long “recovery” sheath after first modifying the tip of the dilator. The distal tip of the standard, large French sized, long dilator, which comes with the sheath, is excised in small increments until the lumen of the excised tip of the dilator at its distal end just will accommodate the snare catheter. The snare catheter is passed through this modified dilator and the combined snare catheter/dilator is introduced into the large, long sheath. An alternative to modifying the tip of the dilator of the recovery sheath is to use the dilator from one of the larger AGA™ “replace- ment” long sheath/dilator sets, which already have a large central opening. Passing the snare catheter through the dilator serves two functions. First it “centers” the snare catheter within the lumen of the large sheath and allows the offset of the snared hub of the device to be drawn into the sheath without catching on the edge of the tip of the sheath. The dilator within the sheath also adds significant additional support to the long sheath and prevents or reduces the accordion effect on the shaft of the sheath when strong traction is necessary to withdraw the device into the sheath. Once the “attaching post” on the device is manip- ulated into the tip of the long sheath, the device can be withdrawn and folded into the larger sheath much like it was when it still was attached to the delivery cable. Once within the sheath, it is withdrawn out of the body. If the right sided central post of the errant device cannot be grasped, the device is grasped by an edge of one of the disks with a bioptome catheter and re-manipulated/re- orientated until the “post” becomes accessible to the snare. Trying to withdraw the device when it has been grasped anywhere except by the central hub, markedly distorts the device and makes the narrowest profile of the collapsed device significantly larger and unreasonable to be with- drawn into any sheath, even if it is 4 or 5 French sizes larger than the original delivery sheath. This type of retrieval of an Amplatzer™ device probably should not be attempted, in which case surgical retrieval is the most reasonable option. As with any other device that embolizes to a pulmonary artery, the retrieval sheath must be advanced into at least the main pulmonary artery before attempting to capture the device and the errant device must be withdrawn com- pletely into the sheath before it is withdrawn out of the pulmonary artery. A partially (or fully!) opened device should not be dragged through the right ventricle (and tricuspid valve). Unless the operators are extremely skilled at foreign body removal and extremely patient, when the device embolizes to the right ventricle, left vent- ricle or pulmonary artery it is judicious to have the device removed surgically. There have been several very rare occurrences of pre- mature release of the Amplatzer™ ASD device related to inadvertent unscrewing of the device while manipulating the delivery cable and sheath and/or due to a “defect” in the attaching screw at the end of the delivery cable. The premature release resulted in the embolization of several devices, but no permanent complications. The screw has been changed and this should eliminate this problem when the device is used properly. The delivery cable has been “unwound” during unusually vigorous use, but this does not occur with standard use. There are several pending modifications of the Amplatzer™ ASD delivery systems which should im- prove the delivery and make the delivery and implant of the Amplatzer™ ASD device even easier and safer. A new, reinforced sheath has been developed, which can be torqued and advanced without kinking, and presumably will not “accordion” as readily when devices are withdrawn into it. The new sheath is available with an angled distal tip to orient the device and to align it better with the septum as it is extruded from the sheath. The use of the Hausdorf ™ modification of the RB-MTS™ sheaths was mentioned earlier under delivery techniques and certainly obviates many of the problems of the current AGA™ sheaths. CardioSEAL™ and STARFlex™ ASD Occluders The CardioSEAL™ and STARFlex™ Septal Occluders (NMT Medical Inc., Boston, MA) are second and third CHAPTER 28 Atrial septal defect occlusion 753 generation, respectively, double-umbrella, ASD occlud- ing devices modeled after the original Clamshell™ ASD Device (USCI BARD, Glens Falls, NY). Each umbrella frame still has four legs and the umbrella material of both devices is a smooth, woven dacron fabric. Otherwise, these two devices represent extensive modifications of the original Clamshell™ in both materials and design 16 . The metal frame of both the CardioSEAL™ and STARFlex™ umbrellas is manufactured from a cobalt-based alloy, MP35n, which, compared to stainless steel, is less corros- ive, more flexible and is a non-ferrous metal. In order to provide even more flexibility to the legs and, at the same time, greater “compression” against the septum, each leg of both the CardioSEAL™ and the STARFlex™ devices is manufactured of a slightly thinner wire and each leg has two hinges, or joints, compared to the single joint on the legs of the Clamshell™ device. The combination of mater- ial and/or the leg changes eliminated the early leg frac- tures and markedly reduced the number of leg fractures altogether. Similar to the earlier Clamshell™ device, the two umbrellas of both the CardioSEAL™ and STARFlex™ devices are attached at the center and fold away from each other into a narrow profile for delivery. The only difference between the CardioSEAL™ and the STARFlex™ devices is the addition of four very fine Nitinol™ spring “centering” wires on the STARFlex™ devices. Each fine Nitinol™ centering wire extends from the tip of a leg on one umbrella to the tip of the nearest leg on the opposite umbrella. CardioSEAL™ and STARFlex™ devices are available in 17, 23, 28 and 33 mm sizes. Originally there was a 40 mm device, however, the legs at that length did not have sufficient strength to compress them securely against the septum, and its use has been discontinued. The “size” of the devices represents the maximum diameter, tangen- tially from the tip of one leg to the tip of the opposite leg, measured across the center of the device. The original CardioSEAL™ devices all required an 11-French long sheath for delivery. The newer “front-loading” adaptation of both the CardioSEAL™ and STARFlex™ devices allows a downsizing to a 10-French delivery sheath for the 17–28 mm devices. The larger sized devices can be intro- duced into a 10-French sheath, but the devices are very tight within a 10-French sheath and advancing the devices through a 10-French sheath is very difficult, if not impos- sible. As a consequence, an 11-French sheath is recom- mended for the delivery of all of the 28 & 33 mm devices. Like the earlier Clamshell™ device, the CardioSEAL™ device has no specific centering mechanism so that a ratio of the device diameter to the defect diameter of 2:1 is rec- ommended for ASD occlusion with the CardioSEAL™ device. The STARFlex™ device has extra Nitinol™ spring centering wires. These centering wires, however, are more useful for centering after, as opposed to during, implant, and as a consequence, the 2:1 ratio for the device to defect diameter still is recommended for the STARFlex™ device. With their increased flexibility and the extra joints in the legs, which tend to fold the legs even more toward the septum during the deployment, the sizing of the ASD for an occlusion with either the CardioSEAL™ or the STARFlex™ device is even more critical. The CardioSEAL™ and the STARFlex™ devices under- went a regulated, multicenter, FDA clinical IDE trial for ASD closure. The CardioSEAL™ device also underwent a high-risk, protocol trial for closure of other intracardiac defects. The CardioSEAL™ was replaced by the newer designed STARFlex™ modification for ASD occlusions. The CardioSEAL™ device received FDA, Humanitarian Device Exemption (HDE) approval in the United States for the closure of a patent foramen ovale associated with systemic embolic events (and which have failed medical management!), and a standard use approval for the clo- sure of surgical fenestrations which are created purpose- fully during “Fontan” type intracardiac repairs and for the closure of muscular interventricular septal defects. The use of the CardioSEAL™ device for the closure of the patent foramen ovale requires notification of the local Institutional Review Board (IRB). At the same time, the HDE approval is an approval for human use and does not require an IDE protocol for these uses. The procedures for each of the “approved uses” of the CardioSEAL™ device are covered in detail in other chapters (29 & 30) under each one of the particular defects, while its use in the secundum ASD is discussed in this chapter in conjunction with the implant techniques for the STARFlex™ device. Currently, the STARFlex™ device is not available in the United States. It was used in one controlled, clinical trial for post- infarct VSD occlusions but apparently this has been aban- doned. Both the CardioSEAL™ and the STARFlex™ devices have CE mark approval for occlusion of the ASD as well as other intracardiac defects, and are in clinical use for ASD occlusions throughout much of the world except the United States 17 . Technique for CardioSEAL™ and STARFlex™ ASD implants Similar to the implant of the Amplatzer™ ASD device and most other atrial septal occlusion devices, the delivery and implant of the device is guided using fluoroscopy with the concomitant use of either transesophageal echo (TEE) or intracardiac echo (ICE). All procedures per- formed with TEE are performed under general, endotra- cheal anesthesia while, when ICE is used to guide the implant of the device, some cases can be performed under deep sedation. If the procedure is expected to be at all long and/or complicated, an indwelling Foley™ catheter is placed the patient’s urinary bladder at the onset of the CHAPTER 28 Atrial septal defect occlusion 754 procedure. In the patient undergoing an ASD occlusion with a CardioSEAL™ and/or a STARFlex™ device, a 9–11-French short sheath is introduced into the right femoral vein, a 6- or 7-French sheath is introduced into the left femoral vein, and a Quick-Cath™ or a blunt tipped, 5-French dilator introduced into a femoral artery. If ICE is used to control the implant, an 11-French, 30 cm long sheath is introduced (instead of, or in addition to, the 6- or 7-French sheath!) into the left femoral vein. An end-hole catheter is introduced into the sheath in the right femoral vein and an angiographic “marker” catheter introduced into the sheath in the left femoral vein. The “right heart” pressures and the right heart saturation “sweep” are acquired with either one or a combination of these catheters. The atrial septum and the atrial defect(s) are interrogated with the TEE or ICE, and preliminary echo measurements of the defect and the rims around the defect are recorded before the catheters are advanced through the defect. When an angiographic “visualization” of the atrial septum is desired, the angiographic catheter then is manipulated through the ASD and into the right upper pulmonary vein. The end-hole catheter is advanced through the ASD and well into a left upper pulmonary vein. One of the X-ray tubes is angled into an approximate 45° LAO–45° Cranial angulation and an angiogram is recorded with injection into the right upper pulmonary vein. The angiogram with this angulation should “cut” the atrial septum on edge on the angiogram and provide an angiographic picture of the size and approximate loca- tion of the ASD. Often, this angle of the X-ray tube does not profile the ASD adequately, in which case the X-ray tube angle is changed appropriately and the angiogram repeated. Once the optimal angiogram has been recorded and the measurements of the atrial defect have been recorded by echo (and angiogram if performed), an exchange length, 0.035″ Super Stiff™ guide wire with a short floppy tip is introduced into the end-hole catheter through a wire back-bleed/flush valve and wedged into a left upper pul- monary vein. The end-hole catheter is maintained over the wire and on a continuous flush until immediately before the sizing balloon is introduced. Once a NuMED™ sizing balloon (NuMED Inc., Hopkinton, NY) with a maximum diameter of approximately twice the measured diameter of the ASD as determined by TEE/ICE and/or angiogra- phy, has been prepared, the end-hole catheter is with- drawn off the wire and the sizing balloon is introduced through the short sheath and over the Super Stiff™ wire. The sizing balloon is maintained on a flush over the wire through a wire back-bleed/flush device and advanced until it straddles the ASD. A static, non-stretched balloon sizing of the ASD is performed in order to obtain the diameter of the defect for occlusion with either the CardioSEAL™ or the STARFlex™ device. The balloon is inflated partially and at “zero pressure” until a malleable, circumferential waist appears around the balloon. If necessary, the angle of the X-ray tube is adjusted to “cut” this waist and the atrial septum more precisely on edge. This waist on the partially inflated balloon is measured angiographically and by TEE or ICE as the non-stretched diameter of the ASD. When using either the CardioSEAL™ or the STARFlex™ devices, the device chosen for an ASD occlu- sion should be at least twice the non-stretched, static balloon sized diameter of the atrial septal defect. The CardioSEAL™ and STARFlex™ devices both require at least 6–7 mm (measured by TEE or ICE) of atrial septal rim circumferentially around most of the atrial defect, in order to provide the legs some tissue to attach to and to hold the device in place. Inferior–caudally, the rim above both of the atrioventricular valves must be at least the length of the radius of the particular device being used in order to accommodate the maximum length of a leg of the device (which corresponds to the radius of the device) without touching either atrioventricular valve. If a CardioSEAL™ or STARFlex™ device is positioned eccentrically, a leg can extend the full length of that leg past the rim or edge of the ASD. When the defect is otherwise fairly central and there is sufficient rim everywhere else, the aortic (anterior– superior) rim can be deficient for 10–15° of the circumfer- ence of the rim of the atrial septal defect. Once the defect is accurately measured and the device is chosen for the particular defect, an appropriate French sized, long sheath is chosen for the delivery of the CardioSEAL™ or STARFlex™ device. A 10-French long sheath is used for the 17 and 23 mm devices while an 11- French long sheath is used for the delivery of the 28 and 33 mm CardioSEAL™ and STARFlex™ devices. A long, large (10–11-French) delivery sheath/dilator set is pre- pared especially for the delivery of an ASD device. Most of the long sheath/dilator sets that are supplied from the manufacturers either are absolutely straight or have a 180° “transseptal” curve on them. These curves on the sheaths/dilators should be re-formed to more appropri- ate curves for the delivery of any ASD device. The pre- ferred curve for the delivery of either a CardioSEAL™ or STARFlex™ device to an ASD is a gentle 45° curve just proximal to the distal end of the sheath, with a second “third-dimensional”, fairly tight, 45° posterior-superior- leftward curve (as the tip of the sheath faces away from the operator) superimposed distally on the first curve at the very end of the sheath. The more proximal curve directs the sheath from the IVC, leftward, through the ASD and toward the lateral wall of the left atrium, while the distal and posterior curve at the tip of the sheath directs the tip toward the right posterior-superior left atrium. CHAPTER 28 Atrial septal defect occlusion 755 This particular combination of curves now is a vailable commercially preformed as the Hausdorf-Lock™ mod- ification of the RB-MTS™ sheaths (Cook Inc., Bloomington, IN). It is available in 85 cm lengths and in 10–12-French diameters. Unfortunately, the manufactured Hausdorf™ curves all have the same fixed distance between the more proximal and the very distal curves on the end of the sheath. The specificity of this complex curve for a particu- lar ASD depends on the lengths of the curves correspond- ing to the lengths in the particular heart. As mentioned above, the curves on the sheath/dilator can be formed/ changed after heating and with experience and/or trial and error can be formed to fit the specific patient. Delivery sheaths with the “Hausdorf™” curve frequently are used for the delivery of all ASD occlusions devices, but are particularly important for delivery of the CardioSEAL™ and STARFlex™ devices. Before the long sheath/dilator for the delivery of the device is introduced into the vein, the long delivery sheath/dilator is passed through a short, stiff, 14+-French, “recovery”, sheath while outside of the patient. A short, thin-walled, 14+-French, metal cannula makes the ideal recovery sheath. The 14+-French, short sheath (or metal cannula) is withdrawn over the long sheath, and posi- tioned back against the hub of the long sheath. The short “recovery” sheath remains there throughout the proced- ure and is not advanced over the long sheath nor intro- duced into the skin during a normal ASD device delivery. This larger diameter, short, pre-placed, “recovery” sheath is introduced into the skin and vessel only for the event that it is necessary to remove an incompletely folded CardioSEAL™ or STARFlex™ device from the femoral vein. Otherwise, the larger diameter, short “recovery sheath” remains back at the proximal hub of the long sheath and completely out of the skin/vessel. After the waist on the static balloon has been measured angiographically and by TEE or ICE, to determine the diameter of the defect, and once the long sheath has been prepared for the device delivery, the sizing balloon is withdrawn carefully from the ASD over the Super Stiff™ wire, which remains positioned in a left upper pulmonary vein. The original short sheath in the right femoral vein is withdrawn over the wire along with the sizing balloon catheter. The long delivery sheath is flushed through the side port of the back-bleed valve and then the stopcock of the side port on the long sheath is turned off. The wire back- bleed/flush valve from the sizing catheter is attached to the dilator of the long sheath/dilator set and the side port of the wire back-bleed device, which is on the dilator is maintained on a continuous flush while the sheath/dila- tor set is introduced over the wire and advanced into the skin and the vein. With the dilator maintained on continuous flush and the valve of the side port of the sheath closed and not on a flush, the long sheath/dilator set is advanced over the wire until the tip of the dilator is visualized on fluoroscopy just at the area of the inferior vena cava–right atrial junction. As mentioned earlier in the discussion of the Amplatzer™ ASD Occluder, the next few steps potentially are the most dangerous in the entire procedure. If the proper steps are not taken for removing all air and/or clot from the deliv- ery system, the patient is very likely to experience a sys- temic embolic event during the subsequent exchanges of catheters and wires and/or the introduction of the device through the long sheath. With the tip of the Hausdorf™ dilator (and sheath) still in the right atrium and the dilator still on continuous flush, the dilator is withdrawn slowly and carefully until the tip of the dilator is within 10 centimeters of the proximal end (and hub) of the long delivery sheath. The tip of the dila- tor, still within the sheath, easily is palpated within the sheath as the dilator is being withdrawn out of the subcut- aneous tissues and past the surface of the skin. When the tip of the dilator reaches a position outside of the skin but still within the sheath, the flush on the dilator is stopped. With the flush on each part of the system stopped, the di- lator is withdrawn very slowly over the wire out of the last 10 centimeters of the sheath and completely out of the back-bleed valve of the sheath. If there is any, even slight obstruction at the tip of the sheath and/or if the dilator is withdrawn too fast even with the wire passing through a back-bleed/flush valve, air usually will be sucked around the tip of the dilator and, in turn, into the lumen of the sheath around the wire as the dilator is withdrawn! When there is no back-bleed valve on the dilator, air easily can be sucked into the dilator (and sheath) around the wire dur- ing the entire time as the dilator is being withdrawn from the sheath. Once the dilator is withdrawn completely out of the sheath over the wire, the sheath again, meticulously and passively, is cleared of air and/or clot. While watching the fluid column within the tubing on the side port of the long sheath very closely, the stopcock of the side port is opened very carefully and allowed to bleed back passively to empty all potential air and/or clots from within the long sheath and the valve chamber of the sheath. Extreme care is taken as the stopcock initially is opened just barely to ensure that fluid and/or air are flowing out of, and are not being sucked into the sheath by negative intrathoracic pres- sure. Realizing that a 10- or 11-French sheath can hold 10–12 ml of air and/or clot, the sheath is allowed to bleed back passively until a column of blood with no air bubbles mixed in it flows freely out of the side port. During the clearing of the sheath, the hub of the sheath is rotated around, elevated (off the table top if possible) and tapped briskly to dislodge air bubbles which always will be lodged within the chamber of the back-bleed valve regardless of how well it was cleared and/or how CHAPTER 28 Atrial septal defect occlusion 756 thoroughly the sheath and dilator were flushed originally before the dilator was introduced into the sheath! If fluid and/or blood do not flow freely out of the side port of the sheath, the stopcock is turned off immediately. Suction never is applied to the side port at any time when there is a wire and/or catheter passing through the back-bleed valve of a sheath. If suction is applied to the side port, a vacuum is created in the sheath and chamber of the back-bleed valve. When there is a wire/catheter passing through the valve, the path of least resistance to the vac- uum is through the back-bleed valve around the wire and any suction results in more air being sucked into the sheath around the wire! If fluid and/or blood do not flow pas- sively out of the side port of the sheath, deep hand pres- sure is applied over the patient’s upper abdomen and/or the anesthesiologist provides positive airway pressure as the closely observed stopcock is carefully reopened. Both maneuvers increase intra-abdominal and intrathoracic pressures and usually result in air, fluid and/or blood flow out of the side arm of the sheath. If there still is no passive back flow from the sheath, possibly because of low venous pressure and/or an obstructed tip of the sheath, first the sheath is withdrawn slightly and the side port is again opened carefully under close observation. If passive back bleed is not obtained with any of these maneuvers, the sheath is removed com- pletely out of the body over the wire leaving the wire in place. The removed sheath is inspected outside of the body for kinks and/or clots, flushed thoroughly outside of the body, the introduction of the sheath/dilator restarted and the clearing of the sheath repeated until successful. Once absolutely sure that the sheath with the tip of the sheath still in the right atrium has been cleared completely of air and/or clot, the sheath is placed on a continuous flush through the side port of the back-bleed valve. The sheath alone is then advanced carefully over the wire through the atrial defect and deep into the left atrium. Occasionally there is a slight resistance or “catch” as the wide, blunt tip of the sheath catches on the rim of the defect, especially with a small atrial septal defect. In the event of any resis- tance, the sheath is moved to and fro and rotated very slightly as it is advanced. The sheath never should be pushed forward forcibly. If the sheath cannot be advanced into the left atrium easily, the dilator with a back-bleed valve on full flush is reinserted over the wire and into the sheath. The sheath/dilator combination is advanced into the left atrium, the dilator removed and the sheath cleared of air even more meticulously than just described. When the sheath is well within the left atrium as visual- ized on fluoroscopy and/or by TEE/ICE, the wire is with- drawn slowly. Again, when the wire is completely out of the sheath, the sheath is allowed to bleed back passively as described above and again cleared of any potential air and/or clot. If there is no passive back flow from the side arm of the sheath after the wire is withdrawn completely, the back-bleed valve on the hub of the sheath is covered firmly with a gloved finger in order to “seal” the valve very tightly. With the valve sealed tightly with the finger, gentle suction is applied to the side port until there is a good, free flow of only blood from the side arm. Once the sheath is full of blood, after suction is stopped and before flushing, it is a good idea to “vent” the back-bleed valve by introducing the tip of a dilator or the tip of a small for- ceps into the “leaflets” of the back-bleed valve to partially “open” it while letting it bleed back passively and to con- tinue the venting while beginning the flush into the side port of the sheath. If none of these techniques results in a good flow of fluid/blood from the side port of the sheath, a new wire is introduced and advanced very carefully through the sheath to the level of the inferior vena cava, the wire is fixed in this position, the sheath is removed over the wire and replaced, starting from the very begin- ning of the procedure. Once cleared in the left atrium, the sheath is flushed thoroughly and maintained on a slow flush, remembering that a long 10- or 11-French sheath has a capacity of 12+ ml of fluid, air and/or clot! Placing the valve and the side port of the sheath under “water” in a basin of fluid during the entire loading and introduction procedure has been advocated to prevent air from entering the sheath through the valve and around the wire. This does prevent air from being sucked into the valve and sheath from outside, but does not eliminate any air which alreadyaand almost alwaysais trapped within the valve “chamber” of the sheath after the dilator is removed, it does not eliminate air introduced through the dilator and/or delivery catheter, nor does it prevent any air which already is present in the sheath from being flushed into the left heart! This “under-water” technique only instills a sense of false security. The location of the tip of the sheath in the left atrium is confirmed on fluoroscopy and by TEE/ICE. If there still is any question about the location of the tip of the sheath and particularly when there is concern that it is trapped in the atrial appendage or in a pulmonary vein, a slow hand injection of 5–10 ml of contrast, followed by 10–15 ml of flush solution is performed through the sheath in order to verify the exact position of the tip of the sheath. After this hand angiogram, the sheath is flushed thoroughly and the side arm of the sheath is maintained on the slow, con- tinuous flush while the device and delivery catheter are prepared. With the Hausdorf™ curve on the sheath and after the tip is withdrawn out of the appendage or left pulmonary vein, the preformed posterior curve at the tip of the sheath deflects the tip toward the posterior wall of the left atrium and/or even toward the right-posterior-superior aspect of the left atrium near the right upper pulmonary veins. The position of the sheath passing through the septum is seen CHAPTER 28 Atrial septal defect occlusion 757 clearly on fluoroscopy and verified with TEE/ICE. The TEE/ICE also shows clearly how the course of the distal sheath in the left atrium tends to run tangentially or even parallel to the plane of the septum. This alignment to the septum becomes very important as the device eventually is withdrawn to, and against, the septum during delivery. Once the sheath is in position in the left atrium for the device delivery, the appropriate CardioSEAL™ or STARFlex™ device and delivery system are opened, inspected and prepared for the device introduction. The loader, delivery catheters and delivery systems are iden- tical for the CardioSEAL™ and STARFlex™ devices. A delivery rod entering the proximal end of the catheter is at the proximal end of, and controls the to-and-fro move- ment of the central delivery wire, which extends out of the distal end of the catheter. There is a locking nut proximal to a Tuohy™ side port adaptor on the proximal end of the delivery catheter which, when tightened, prevents the delivery rod (and wire) from moving either in or out of the catheter at all. This locking nut is attached to the Tuohy™ side port/flush mechanism. The side flushing port at the proximal end of the delivery catheter allows only a very slow flush of the entire length of the delivery catheter around the delivery rod/wire through the side port of the Tuohy™. For attaching (and releasing) the device to the delivery wire/catheter there is a molded plastic, slide-tumbler with a flat, plastic, plate-like, locking mechanism on the proximal end of the delivery rod. When the tumbler, which is at the proximal end of the delivery rod, slides forward, it pushes a “locking pin” out of a tiny “retaining” sleeve at the distal end of the delivery wire. Withdrawing the tumbler withdraws the pin into the tiny sleeve. The flat, plastic, locking plate, which lies flat on one side of the tumbler, locks the tumbler (and pin) in place by two small protuberances on the tumbler, which fit into two holes on the locking plate. The locking plate is raised slightly off the tumbler to unlock the tumbler and allow the tumbler with the attached control wire to move forward or back- ward. The plastic locking plate does not deform easily when it is elevated off the tumbler during the attachment or the release of the device, however, it can be distorted and not function subsequently if raised too high and/or forcefully off the surface of the tumbler. The locking plate is elevated just enough to release the tumbler. The loading of the current CardioSEAL™ and STARFlex™ ASD devices are totally different from the loading technique for the Clamshell™ and the earlier CardioSEAL™ devices. The CardioSEAL™ and STARFlex™ ASD devices both now use the same “front- loading” system and technique. The current delivery catheters no longer have the large metal “delivery pod” at the distal end of the delivery catheter, and the device actu- ally is not loaded into the delivery catheter at all but into a loader and from there directly into the long pre-positioned delivery sheath. The attach/release mechanism for both the CardioSEAL™ and STARFlex™ ASD devices still is the so-called overlapping “ball-to-ball” (or pin-to-pin) mech- anism within a tiny constraining sleeve. It is similar to the Clamshell™ and earlier CardioSEAL™ attach/release mechanisms except that the tiny ball on the attach/release wire now withdraws to just within the tip of the tiny sleeve. On the earlier versions of the pin-to-pin mechan- ism for the CardioSEAL™ device, when the tumbler was locked, the ball on the delivery wire was pulled deep within the sleeve. The deep recess of the tiny ball into the sleeve did provide a very secure lock on the ball of the device, but at the same time, it did not allow any mobility and/or angulation of the pin on the device (and/or the device) when it was attached to the tip of the delivery catheter. With the current devices, the ball on the attach/release wire is recessed precisely and just within the tip of the sleeve when the tumbler is retracted “fully”. As a consequence, the pin attached to the device (along with the device) can angle within the sleeve as much as 45° off the long axis of the catheter with the device still attached very securely. If the ball at the tip of the pin on the device does retract deep within the small sleeve when the device is attached, the delivery catheter is defective and should not be used. The lumen of the delivery catheter is flushed free of air through the side port of the Tuohy™ “Y” adaptor on the delivery rod. After flushing, the locking nut is loosened and the delivery rod is advanced into the catheter so that the distal delivery wire with the attached distal sleeve extends all the way beyond the end of the catheter. A very gentle, long curve is formed on the exposed delivery wire. The curve on the wire is approximately 30° off the long axis and is approximately 20 cms in length. This curve is longer and gentler than the curves formed at the end of the long sheath. This curve is formed on the wire so that the curve on the wire conforms to the gentle curvature of the sheath passing from the right atrium into the left atrium and maintains this same curve after the sheath is with- drawn completely off the device during delivery to the ASD. The catheter is inspected for proper function of the attach/release tumbler in advancing the release pin/ball in and out of the sleeve, for the free movement of the delivery rod through the loosened lock nut, and for the free movement of the rod/wire within the catheter. The small sleeve is carefully inspected to be sure that the sleeve is fixed firmly to the delivery wire and that the ball on the pin in the sleeve is positioned just within the tip of the sleeve when the proximal slide tumbler is withdrawn fully and is in the locked position. The selected occluder device is opened, inspected and soaked in saline. The device comes attached to a CHAPTER 28 Atrial septal defect occlusion 758 Quick-loader™. The Quick-loader™ is a thin-walled, semi-clear plastic tube with a 10-French internal diameter and a small lucent funnel which is fixed on the proximal end of the loading tube. The thin-walled loading tube is contained within a thick transparent Lucite casing. This Lucite casing only serves to reinforce the thinner tubing of the Quick loader™ during the loading. A single, long loading suture passes through the Quick-loader™, out through the proximal (funnel) end of the loader, through all four of the “eyelets” at the tips of the legs of the distal umbrella of the device, and back through the proximal end of the loader. The loading suture is tied through a plastic button at the distal end of the loader. Loading into the Quick-loader™ is accomplished by pulling the attached device into the loader with the attached “loading” suture. The properly operating Quick- loader™ system requires very little traction on the sutures to draw the device into the loader. If excessive tension is applied to the suture as the CardioSEAL™ or STARFlex™ device is pulled into the loader, the excessive traction can over-extend and distort the hinge/spring mechanism of the central hinge of the device, with the disastrous result that the device does not open properly when delivered. This almost always is the case when the larger sized CardioSEAL™ and STARFlex™ devices are used with the Quick-loader™ and, as a consequence, the manufacturer’s supplied Quick-loader™ now only is used for the 17– 23 mm devices by this operator. A modified loader that is much less traumatic to the devices than the manufac- turer’s system, is used for the 33 mm and even the 28 mm devices, and is described subsequently. The tiny attaching “ball” is fixed permanently on the exposed end of the short pin that is on the central hinge of the proximal umbrella. To attach the device to the delivery sys- tem, the tiny ball on the delivery/release wire is extended partially out of the sleeve by advancing the tumbler mech- anism at the proximal end of the delivery catheter. The tiny “ball” on the device is positioned beside the wire to which the ball on the delivery system is attached and is introduced into the tiny sleeve. While maintaining the ball on the device within the sleeve, the ball on the deliv- ery/release wire is withdrawn into the sleeve by with- drawing the tumbler at the proximal end of the catheter. The ball on the device will be locked into the tiny sleeve when the protuberance on the tumbler snaps into the small hole on the plastic latch. The attached wires of the two tiny balls now overlap each other and pass adjacent to the wire of the opposite ball all within the tiny sleeve. The “compression” by the small inner diameter of the tiny sleeve keeps the ball of the device from sliding out of the sleeve past the ball on the delivery/release wire. The ball on the device is not released until the delivery/release wire (and attached ball on the wire) is advanced purpose- fully out of the sleeve. At the same time, with the proper positioning of the two tiny balls within the sleeve, the device moves freely, angling from side to side at the end of the delivery wire/sleeve. When using the manufacturer’s Quick-loader,™ the device, which now is attached to the delivery catheter and has the suture passing through the loader, is re-moistened with flush solution. Traction is applied to the button at the ends of the suture which passes through the Quick- loader™ while equal traction is applied straight and in the opposite direction to the delivery catheter. Just enough traction is applied to fold the four distal legs of the device, through which the suture passes, symmetrically away from the catheter and toward the funnel of the Quick- loader™. A slow continual flush of saline is injected into the “funnel” while the device is pulled straight into the Quick-loader™ by the suture. The flush “lubricates” the device and helps to prevent air from becoming trapped within the device and loader. As the suture is pulled fur- ther, the tips of the legs of the distal umbrella, which are folded toward the funnel, are pulled into the open end of the funnel. With further gentle traction on the button/ suture, as the device is pulled into the loader, the distal legs are compressed together very tightly. With further traction on the suture, the folded, distal umbrella is pulled into the tubular portion of the loader while the proximal, following, umbrella is pulled into the funnel and the prox- imal legs are folded in the opposite direction by the funnel (toward the delivery catheter) as the device is pulled fur- ther into the funnel. Continued, straight traction is applied to the “button” (and suture) while the tension is released and a slight push toward the loader is applied to the attached catheter. This completely folds, compresses and pulls/pushes the device entirely into the tubular portion of the loader. Only mild traction on the loading suture ever should be neces- sary to fold the umbrellas and draw the device into the loader during the loading into a properly sized Quick- loader.™ Whenever any resistance is encountered while pulling the device into the loader, the alternative loader should be used. When there is no extra resistance, the folded device is pulled/pushed to the distal tip of the thin sleeve of the Quick-loader™. In the loader the two appos- ing umbrellas of the device now are folded 180° away from each other for delivery. It also is very important that, during all of the steps of the device introduction into the loader, the device is pulled straight into the Quick-loader™ with no twisting or rotating of the loader, the suture or the device. Any rotation of the device/loader during loading can twist the adjacent legs of the device over each other within the loader. Any twist- ing of the legs over each other potentially prevents proper opening of the device during delivery. The 33 mm and the original 40 mm device were always very difficult to pull into the manufacturer’s [...]... other, a single, in ated, sizing balloon may “compress” the adjacent defects together and eliminate shunting, or a sizing balloon that is in ated to stretch-size one defect can disrupt a thin strip of tissue that is separating two adjacent defects and, in turn, coalesce the two defects into one larger opening In either of those circumstances a single device with a “centering hub” that “stretches” into the... preliminary results with a new self-expanding nitinol prosthesis in a swine model Circulation 199 7; 95 : 2162–2168 14 Bjornstad PG et al Interventional closure of atrial septal defects with the Amplatzer™ device: first clinical experience Cardiol Young 199 7; 7(3): 277–283 Atrial septal defect occlusion 15 Levi DS and Moore JW Embolization and retrieval of the Amplatzer septal occluder Catheter Cardiovasc Interv... devices, intracardiac echo (ICE) during the delivery and implant may obviate the need 7 69 CHAPTER 28 Atrial septal defect occlusion for TEE and, in turn, general anesthesia An arterial monitoring line and two venous catheters are used The right heart catheterization is performed to quantitate the ASD and rule out associated defects An angiographic “marker” catheter is introduced from the left groin and. .. occlusion devices are in, and/ or have undergone successful clinical FDA, IDE trials in the United States and are awaiting FDA decisions for clinical use With some understanding of the uniqueness of both the lesion and the pediatric and congenital patients, a reasonable decision from the FDA could result in the availability by the time of this publication of at least one more of these devices being approved... ductus arteriosus: clinical application of the Rashkind PDA Occluder System Circulation 198 7; 75(3): 583– 592 11 Gu X et al A new technique for sizing of atrial septal defects Catheter Cardiovasc Interv 199 9; 46(1): 51–57 12 Kreutzer J et al Healing response to the Clamshell device for closure of intracardiac defects in humans Catheter Cardiovasc Interv 2001; 54(1): 101–111 13 Sharafuddin M et al Transvenous... micro spring wires are inspected in particular to be sure that they are not damaged (overstretched and/ or “unwound”) and that they are not entangled with the legs, hinges, fabric or sutures on the devices Keeping these tiny wires free and untangled is particularly important during the loading of the STARFlex™ device into the Quick-loader™ or the modified loader When one of the tiny micro wires becomes... an increased sensitivity over TTE, but are not as selective as TEE at detecting a PFO with shunting9 Transthoracic echo using second harmonic imaging to enhance the contrast of the “micro bubbles” following the injection of “contrast” material during a Valsalva maneuver appears markedly improved over standard TTE, and closer in sensitivity to TEE for documenting the presence of right to left shunting... catheter is introduced into the right femoral vein through a 9 11-French short sheath The end-hole catheter is advanced through the foramen, past the angiographic catheter and manipulated deep into a left upper pulmonary vein The end-hole catheter is maintained on a continuous flush through the wire back bleed/flush port and an exchange length, short tipped 0.035″ Super Stiff ™ wire (Medi-Tech, Boston... withdraw even part of the device into the sheath The delivery catheter is re-advanced over the delivery cable and against the pin connector of the device to add support to the shaft of the long sheath The combination of catheter, delivery wire and deployed device are withdrawn against and, as much as possible, into the long sheath, which, of course, in doing so, destroys the device When applying this force,... device only buckles and/ or accordions the long sheath In order to remove the partially withdrawn device from the vessel, first the skin and subcutaneous tissues around the long delivery sheath are in ltrated liberally with local anesthesia and the skin incision is extended slightly around the long sheath The short 14-French “recovery” sheath is introduced into the vein over the 11-French long sheath . the CardioSEAL™ and STARFlex™ ASD devices still is the so-called overlapping “ball-to-ball” (or pin-to-pin) mech- anism within a tiny constraining sleeve. It is similar to the Clamshell™ and earlier. CardioSEAL™ and/ or a STARFlex™ device, a 9 11-French short sheath is introduced into the right femoral vein, a 6- or 7-French sheath is introduced into the left femoral vein, and a Quick-Cath™ or. sheath/dila- tor set is introduced over the wire and advanced into the skin and the vein. With the dilator maintained on continuous flush and the valve of the side port of the sheath closed and not