Cardiac Catheterization in Congenital Heart Disease: Pediatric and Adult - Part 5 ppt

CHAPTER 12 Foreign body removal 369 carrier catheter, the straight thread wire is advanced out of the carrier catheter and through the eye of the hook. The hook is then withdrawn into the carrier catheter and, in turn, tightens against the thread wire on the opposite side of the foreign body, thus encircling and grasping the foreign body very securely (Figure 12.2). The Needle’s Eye™ snare is the strongest of the retrieval systems and the most likely to be able to dislodge securely embedded foreign bodies. This same character- istic makes this device more dangerous to use. In addition to being very large in diameter, the entire system is very stiff. When the hook is extruded, the wire loop of the hook is capable of digging into the tissues as well as excavating around foreign bodies. As a consequence, perforations are certainly possible both while extruding the hook and when pulling the foreign body loose. The Needle’s Eye™ system is very strong, and the grip on a foreign body is very tight and secure. Any tissues around a foreign body that grip it securely will tear before the Needle’s Eye™ mechanism releases or gives way, so there is a real danger of tearing vital tissues when extracting a foreign body forcefully with the Needle’s Eye™ device. At the same time, the Needle’s Eye™ can be released more readily from a grasped foreign body. The hook of the device is re-advanced to loosen it, the thread wire is withdrawn, and then the hook can usually be withdrawn from around the foreign body. Adjunct devices for foreign body retrieval There are several other catheter accessories or catheter devices that are designed primarily for other uses which, however, are very useful adjunct devices for the retrieval of foreign bodies. These accessory devices are usually used in conjunction with another specifically designed retrieval device/system. The most commonly used of these adjunct devices are the bioptome forceps and the Amplatz™ controllable deflector wires (Cook Inc., Bloomington, IN). Bioptome forceps Relatively large bioptome forceps (6- or 7-French) are used as an adjunct in the retrieval of many foreign bodies. The bioptome is frequently used to loosen, to reorient or to “expose” part of a trapped foreign body so that it can be grasped with another, stronger retrieval device, although occasionally the complete retrieval can be accomplished with the bioptome. The bioptome has the one major advantage of being able to grasp the side or a small portion of a foreign body without the necessity of encircling it completely. Similar to the other retrieval systems, the bioptome is used through a large diameter, long sheath with a back-bleed valve and a side arm flush port. The sheath should be 3–4 French sizes larger than the bioptome catheter in order to accommodate the grasped foreign body. The long sheath is delivered, as previously described, to a position where the tip of the sheath is pressed against, and abutting a portion of the foreign body. This usually will be against a portion that extends off the surface of the main mass of the foreign body. Keeping the sheath in this position the bioptome is advanced in the sheath until the tip of the bioptome is just within the tip of the sheath. The bioptome jaws are opened as wide as possible within the tip of the sheath and maintained in the maximum open configuration as the bioptome catheter is advanced out of the tip of the sheath. As the bioptome extends beyond the end of the sheath, the jaws open further and completely. The opened jaws are now forced against the loose or protruding piece of foreign body, and as the bioptome is advanced, this piece of foreign body becomes forced within the open jaws. If the bioptome jaws are not positioned exactly over the piece of foreign body, the sheath and the bioptome catheter are maneuvered together until Figure 12.2 Needle and eye encircling a piece of catheter. CHAPTER 12 Foreign body removal 370 the open jaws can be pushed against the desired portion of the foreign body. By continuing to advance the bioptome catheter with some forward force as the jaws are closed, the force is applied against the foreign body and the jaws close around a part of the foreign body. Once the jaws have gripped the loose piece of foreign body tightly, an attempt is made to withdraw the bioptome catheter with the attached foreign body into the sheath and completely out of the body through the sheath. The withdrawal is observed on fluoroscopy to ensure that the foreign material does not become dislodged within the sheath. Because of the small size of the “mouth” and the smooth but sharp jaws of the bioptome, it is only usable with small diameter pieces of catheters or other foreign bodies of fairly small diameter, such as errant guide wires. When the foreign material is too large or rigid, the bioptome jaws tend to slip off the foreign body. Although the bioptome may not be able to grasp the foreign body securely enough to retrieve it completely, it can often dislodge an edge or part of the foreign body enough for another retrieval device to grasp it more securely. The bioptome is most effective on pieces of foreign material that can be crushed partially by the bioptome jaws such as a piece of catheter, wire or small intravascular plastic tubing. At the same time, the grasped material cannot be too soft. Bioptome blades are designed for cutting rather than grasping, and if the foreign material is too soft, the bioptome cuts through the material creating several pieces instead of the original one piece of foreign material! The bioptome is most useful when the foreign body is wedged very far distally in a small vessel or when only the side of an errant catheter, wire, or tubing is accessible with no free ends protruding into the vessel lumen. The bioptome is particularly useful for retrieving or unwinding coils that have embolized to the distal pulmonary arteries. The bioptome may not develop a strong enough grip to pull the foreign material completely into the sheath or completely free of the surrounding tissues without cutting it, however, the bioptome is still very useful for dislodging or moving a foreign body from one area to another. It is also useful for dislodging and then holding a piece of foreign material in a fixed position, allowing the foreign material to be grasped with another retrieval device. For example, a partially opened snare can be introduced over a bioptome catheter that is holding a piece or the edge of a foreign body. The snare loop is advanced into the large long sheath with the partially opened loop of the snare positioned around the bioptome catheter, while the snare catheter passes through the sheath adjacent to the bioptome catheter. As the snare loop is advanced out of the distal end of the sheath, the snare is opened widely and advanced over the piece of foreign material which is already grasped by the jaws of the bioptome. Once past the jaws and now over the foreign body, the loop of the snare is constricted around the foreign body. The foreign body is withdrawn into the sheath while it is grasped by both the bioptome and the snare, or by the snare alone after it has been released from the bioptome. A bioptome type apparatus with toothed or slightly serrated jaws would be a great adjunct for foreign body retrieval. This would allow a secure grasp directly on the side of the foreign material and diversify the use of a bioptome as a retrieval tool. Even without serrated jaws, a bioptome is a frequent adjunct device in the retrieval of foreign bodies. Amplatz™ controllable deflector wire The common Amplatz™ controllable deflector wire (Cook Inc., Bloomington, IN) with a distal curve radius of 10 mm is another very useful device that can be used as an adjunct during foreign body retrieval. Although designed specifically for “bending” or deflecting intravascular catheters, the smaller 0.021″ or 0.025″ deflector wires form a tight curve which creates a 360°, or greater, pigtail type loop when deflected maximally outside of a catheter. The deflector wire is most useful for dislodging or moving embedded foreign bodies rather than for actually retrieving them. A deflector wire that is curved around an errant catheter or other foreign body usually does not hold the catheter or foreign body tightly enough to withdraw it completely. Often, however, the deflector wire can be used either to loosen or to fix a free floating foreign body/catheter enough to allow one of the other retrieval devices to grasp the foreign body more securely. The deflector wire is best suited in the situation where neither end of the foreign body is free or only the middle or side portion of an embolized tubing, wire or catheter is accessible to the retrieval system. The Amplatz™ deflector wire is used through an end- hole carrier catheter that is long enough to pass completely through the long, large diameter retrieval sheath that is being used. A catheter with good torque control and a stiff shaft facilitates the maneuvering of the deflector wire into a position for grasping the foreign body. The deflector wire is introduced through a wire back- bleed valve/flush port on the carrier catheter in order to prevent bleeding around the wire, clots within the catheter, and binding of the wire within the catheter. The distal end of the deflector wire must be able to extend far enough beyond the tip of the carrier catheter (2–4 cm) for the “deflected” portion of the wire to form a complete 360° loop. The long carrier catheter is introduced through a back-bleed valve of a valve/side flush port on the proximal hub of the long retrieval sheath, which must be large enough to accommodate the grasped foreign body and the catheter for the deflector wire as well as another retrieval device/catheter. CHAPTER 12 Foreign body removal 371 The 0.021″ and 0.025″ wires usually form tight 360° loops, however these loops are not very strong, and straighten out if much force is applied to them. The larger diameter deflector wires form stronger loops, but they usually do not form as complete or tight a 360° curve around the foreign body. Because of their minimal strength, deflector wires are used primarily for freeing or reorienting pieces of foreign bodies, wires, catheters or tubing when there is no free end of the foreign body available. Once loosened, a freed end or tip of the foreign body or catheter can be grasped more securely by one of the previously discussed retrieval devices. When using a deflector wire to grasp a foreign body, the long retrieval sheath is positioned with its tip adjacent to, and perpendicular to the piece of catheter, wire, or other foreign material. The catheter that carries the deflector wire is introduced into the sheath and manipulated out of the sheath to a position immediately adjacent to the catheter, wire, or other foreign body that is to be removed. The deflector wire is then introduced through the catheter and advanced out of the tip of the carrier catheter, adjacent to and eventually beyond the errant piece of foreign body. The carrier catheter, deflector wire and deflector handle are rotated so that the concave surface of the carrier catheter (and hopefully the deflector wire) faces the foreign body. When oriented in this direction and the handle of the deflector wire is activated, the concavity of the curve of the deflector wire curves around the piece of foreign body as the wire is advanced further. When the loose piece of foreign body is definitely within the curve of the deflecting wire, the deflector handle is tightened maximally. With the end of the tip of the deflector wire free outside of the catheter, this allows the wire to create a tight, greater than 360° loop around the loose piece, thus encircling it within the tightened loop. While maintaining a tight grip on the deflector handle, the carrier catheter is advanced against the tip of the deflector wire, which is curved tightly back on itself and holding the piece of foreign body. When the tip of the carrier catheter is forced against the 360° loop of wire, it tends to “lock” the curve on the wire. The combination deflector wire, carrier catheter and foreign body is withdrawn toward and, if possible, into the sheath. If the loop of the deflector wire has a tight grip on the foreign body and the tip of the curve on the deflector wire is entirely within the sheath, the entire unit is withdrawn through and out of the sheath. If, on the other hand, the grip on the foreign body is loose or slipping, once the foreign body is within the sheath, it is better to remove the entire retrieval system, including the long sheath, together as a single unit. As with all of the other foreign body retrievals, if the foreign body or any portion of it that is grasped by the loop of the deflector wire is still outside of the sheath, it should not be withdrawn through a ventricle. If the entire loop of the deflector wire or the loose piece of foreign body cannot be withdrawn completely into the sheath, the combined sheath, catheter, deflector wire and foreign body as a unit is withdrawn very slightly within the distal vessel until one end or a piece of the foreign body is free. Once a part of the foreign body is loosened or the foreign body is in a location where another retrieval device can be used, a second, “true” retrieval device is introduced to grasp the foreign body. The “true” retrieval device can be passed through the same long sheath or through a separate, large diameter, long sheath. When the foreign body is difficult to grasp with the curved deflector wire or is in a precarious location, a separate sheath with the new retrieval device is introduced while the foreign body is held with the deflector wire. A tight enough grip then can be created on the dislodged foreign material with the specific retrieval device to allow its withdrawal into the new sheath. An Amplatz™ deflector wire can be used adjacent to a true retrieval system or device as part of the planned retrieval system. When a foreign body appears to be tightly embedded, the true retrieval system is introduced simultaneously with the deflector wire with the loop of the snare pre-positioned over the deflector wire before the two are introduced into the long sheath. The snare and the deflector wire are advanced out of the tip of the sheath together. Once the deflector wire is adjacent to, or passes through, the foreign body, a loop is created on the deflector wire and then tightened, as a result of which it partially grabs and loosens the foreign body. Once an end or a loose piece of the foreign body has been freed, the snare is opened completely and advanced around or over the foreign body and the curved deflector wire that is grasping it. Once the foreign body has been grasped securely with the snare, the curve on the deflector wire can be relaxed to straighten and release the deflector from the foreign body. The loosened and now straight deflector wire can be withdrawn from the foreign body, into, and then out of the sheath. Occasionally, after the foreign body has been held tightly for some time, the deflector becomes entangled with the snare and/or the curve of the deflector wire does not straighten, even after the tension on the deflector handle has been released. When the deflector wire cannot be withdrawn from the foreign body or becomes entrapped within the second retrieval device, the deflector wire and the true retrieval device, along with the foreign body, which is held by both devices, are withdrawn together into the sheath. This does require a slightly larger diameter retrieval sheath. A third alternative is to release the deflector wire completely once even a part of the foreign body has been freed by the deflector wire and before the true retrieval device is introduced. The loosened foreign body is released from CHAPTER 12 Foreign body removal 372 the curve of the deflector wire and the deflector wire is removed from the long sheath. The true retrieval device is introduced through the same long sheath and used to grab the now loosened piece of foreign body. Combinations of retrieval devices Each of the various retrieval devices has a unique applica- tion for different types and orientations of foreign bodies, as described previously in this chapter. However, the various retrieval devices are frequently used together. This was discussed briefly under “adjunct devices” but holds true for any combination of the “true” retrieval devices. One device may be used to loosen or reorient a foreign body so that a different device can obtain a stronger grip or better orientation on it. The second device may be used in addition to, and simultaneously with, the first one to obtain an even stronger grip on a tightly fixed foreign body. Pacemaker lead extractioncspecialized “foreign body” removal Pacemaker leads are deliberately implanted very securely in the myocardium. In this sense, they are not an errant or embolized foreign body. However, an intravascular pacemaker lead can be fractured and no longer function to sense or pace the heart. As such, they serve no positive function and at the same time act as a source of thrombi, mechanical irritation to the heart and heart valves, and act as a nidus for bacterial growth and endocarditis. In most cases an attempt is made to remove intravascular pacemaker leads when they are no longer functional. The transvenous pacemaker lead is usually larger than an errant piece of intravenous catheter, wire, or tubing, and it has been fixed very securely into the myocardium of the heart. Pacemaker leads have usually been in place in the vascular system for very long periods of time, which increases their adherence to the surrounding structures throughout their course through the vasculature. All of these peculiarities of pacemaker leads make their retrieval unique and complex, and have resulted in the development of some very specialized equipment for their retrieval. The removal of intracardiac pacemaker leads is performed only by individuals specifically trained in the use of the specialized equipment and in the techniques of pacemaker lead extraction. This often involves the combined efforts of the electrophysiologist and the interven- tionist. The tools for freeing up the leads are unique and are designed especially for this procedure. The intravascular leads become tightly encased in dense fibrous tissues (old clot!). This fibrous adherence often extends from the site of entrance of the lead into the more peripheral vein, along the entire course of the lead through the vein, to the attachment within the heart. The special tools for the “excavation” and freeing-up of the encased lead from the surrounding adherent fibrous tissues include large diameter, thin walled metal sheaths (Cook Inc., Bloomington, IN) and more recently, large diameter, long “Laser™” cutting sheaths (Spectranetics, Colorado Springs, CO) 4 . Laser™ sheaths emit a laser cutting beam from around the entire circumference of the tip of the sheath. They require a very large and expensive Laser™ generator (Spectranetics, Colorado Springs, CO). The Laser™ sheath has the advantage over thin-walled metal sheaths of being more flexible, and it can follow the lead through its curved course in the vein. Also, with the Laser™’s cutting capabilities, somewhat less brute force is required to push it over the encapsulated lead within the vein. The lead extraction procedure requires a cut-down at the site of the previous, old, scarred cut-down where the lead was originally introduced, and where it enters the vein from the subcutaneous tissues. The entrance site of the lead into the vein is where the lead extraction equipment is introduced. This cut-down is usually in continuity with the surgically formed “pacemaker pocket” and the old pacemaker generator, which is usually removed or replaced. The retrieval sheaths and dilators that are used are larger than much of the comparable equipment used for other transcatheter foreign body retrieval proced- ures. One piece of large, specialized retrieval equipment developed for lead extraction is the locking stylet and sheath that is now commercially available as the Needle’s Eye™ Snare (Cook Vascular Inc., Leechburg, PA), which has already been discussed in this chapter 5,6 . The Needle’s Eye™ is particularly useful for “digging” under a lead or catheter that is embedded in the wall of a chamber or large vein. The first part of the lead extraction procedure is the loosening of the lead from the scarred adhesions along its course from its more peripheral entrance into the vein, centrally through the vein, and to the fixation point in the heart. The cut-down for the lead extraction is usually on the anterior chest wall in the area of the subclavian vein. The lead is freed-up from the subcutaneous tissues outside of the vein and back to the previously implanted pacemaker by blunt and sharp dissection. The lead is disconnected from the pacemaker and the connector is excised from its proximal pacemaker end. The snare end of a special wire snare is introduced from the proximal end of the large extractor sheath and passed completely through the extractor sheath. The extractor sheath can be either a short metal extractor sheath or, preferably, a Laser™ extractor sheath, depending upon the particular circumstances and the preference of the operator. The freed end of the pacemaker lead is grasped securely with the snare wire and pulled into the distal end of the extractor sheath while still outside of the body. Tension is CHAPTER 12 Foreign body removal 373 applied to the snare and, in turn, the freed end of the lead, as the extractor sheath is advanced over the lead and to and into the vein, which is opened with a small incision. While maintaining traction on the snare catheter (and lead), the extractor sheath is forced into the vein and used to cut around the lead, which is encased in scar or old thrombus along its course in the vein. This process requires considerable to-and-fro as well as drilling motion on the extractor sheath, while continually holding tension on the proximal end of the snare wire. As the extractor sheath advances further over the encased lead in the vein and dis- appears into the vein, eventually the original free end of the lead appears at the proximal end of the extractor sheath. Only the more flexible Laser™ sheath can be used once the subclavian/innominate vein makes its turn caud- ally into the superior vena cava toward the heart. With the Laser™ sheath, intermittent laser energy is delivered to the tip of the sheath as this pushing/drilling process along the lead is carried out. This procedure is continued along the entire course of the lead through the vein until the lead has been freed all of the way to its attachment in the myocardium. Once the extractor sheath has reached the “tine” or attachment mechanism of the lead into the myocardium of the heart, the process is continued, but with consider- ably less force and more cautiously. Ideally, the tip of the extractor sheath will drill just to the tip of the lead within the myocardium but no further. Specifically, the tip of the extractor sheath must not drill through the myocardium! While holding the long, stiff sheath in this fixed position even more tension is applied to the proximal end of the lead in an attempt to free the lead from the surrounding myocardium. When the lead has been freed from the myocardium, it is withdrawn through the long sheath. If the lead cannot be withdrawn from its attachment in the myocardium and, particularly, if the lead begins to unravel or otherwise come apart, then a secondary technique for withdrawing the lead must be used. Once the entire course of the lead has been dissected free from the surrounding tissues with the extractor sheath, most of the remaining extraction of the lead is performed from the femoral venous approach. The 14-French sheath of the Needle’s Eye™ snare set (Cook Vascular Inc., Leechburg, PA) is introduced from a femoral vein and advanced to a position adjacent to and perpendicular to the side of the loosened lead and as close to the attachment in the myocardium as possible. The tip of the Needle’s Eye™ sheath will be in either the right atrium or the right ventricle, depending upon the type of lead being extracted. The Needle’s Eye™ snare in its carrier catheter is introduced through this sheath and advanced to the tip of the sheath. The carrier catheter and sheath are maneuvered so that they are touching the side of the lead. The hook of the snare is extruded while simultaneously maneuvering it completely around a free portion of the lead. Once the hook has encircled the lead completely, the thread wire is extruded and advanced through the eye at the tip of the hook (see Figure 12.2). When the eye has been threaded, the hook is withdrawn back into the carrier catheter. This grips the lead very tightly and allows a portion of the grasped lead to be folded on itself and withdrawn into the large sheath. The lead is withdrawn as far as possible into the sheath. By pulling the more proximal lead into the sheath, the tip of the large, long retrieval sheath is pulled against the attachment of the lead in the myocardium. This occurs particularly when the proximal end of the lead has been disrupted or completely withdrawn away from the attachment in the myocardium by the previous manipulations. The side of the lead can still be withdrawn into the sheath, even when the proximal end of the lead is intact and passing out through the superior vena cava and the subclavian vein. Considerable force with intermittent torsion is applied to the Needle’s Eye™ retrieval device that is grasping the embedded lead while counter force is applied by holding or pushing the tip of the sheath over the lead and against the myocardium. This is usually sufficient to pull the lead attachment out of the myocardium. Occasionally, the lead is disrupted further by these forces, leaving a loose seg- ment attached to the myocardium with the free end dang- ling in the cavities of the right heart. In that circumstance, the Needle’s Eye™ retriever is replaced with a basket retrieval device through the same large, long sheath. The basket is manipulated to open around the free end of the lead. The lead is grasped while closing and rotating the basket and, again, as much of the grasped lead as possible is withdrawn into the sheath. Considerable traction and some torque are applied to the basket while the tip of the sheath is pushed against the myocardium to free the lead. Obviously, there are considerable and sometimes poorly directed forces necessary during this procedure for lead extraction. Also there is no direct control over where the long extractor sheath containing the Needle’s Eye™ excavates between the lead and the vessel or chamber walla only that the lead was originally within the vessel or chamber and hopefully the extractor also remains close to the lead and completely within the channel. All of these factors make the extraction of pacemaker leads a fairly dangerous procedure. In fact, because of the dense adherence of the lead to the vascular wall and the tight, often deep fixation of the tip of the lead in the myocardium, it is not a question of whether there will be a complication from a pacemaker lead extraction, but rather, when. Cardiovascular surgical facilities must be available immediately during the extraction of all transvenous pacemaker leads because of the probability of a major vascular or cardiac perforation. CHAPTER 12 Foreign body removal 374 Special foreign body circumstances The extensive use of coils and other devices in the PDA, the larger intravascular stents, and the large occlusion devices for both atrial and ventricular septal defects have created a whole new generation of intravascular foreign bodies. When any of these devices become free floating in the circulation, they create an entirely different challenge for foreign body removal. The handling and removal of these devices are covered in the specific chapters dealing with each device, and are not repeated in this section. Intravascular thrombi and mechanical thrombectomy Although, strictly speaking, intravascular thrombi/emboli do not represent a foreign body, they do constitute intravascular masses that often need to be dissolved or removed urgently. Intravascular thrombi can be the consequence of vascular stenosis with obstruction, localized vascular trauma, underlying low blood flow situations, the presence of a foreign body in the vasculature, hyperco- agulable states, or a combination of any or all of the above causes. As a consequence of a high index of suspicion combined with better imaging modalities, acute thrombo- sis of large vessels can now be detected early, but unless always considered, will go undetected. Better imaging, the very complex surgical repairs now being performed, particularly in the venous circulation, the more frequent intravenous therapy through indwelling lines that are in place over long periods of time, and the extensive manipulations in the vascular system with large catheters/sheaths, may account for what appears to be an increase in large vessel thrombi/occlusions. When a large vessel thrombus is detected, the earlier definitive management is started, the better the chance of removing the thrombus and maintaining or restoring patency of the vessel. Thrombolytics are quite effective at “dissolving” thrombi, however, they are less reliable and slower than mechanical removal, which in the presence of “visible” thrombi, is more rapid and more definitive than thrombolytic therapy alone. Thrombolytic therapy can be used as a general systemic infusion, infused directly into the thrombus, or it can be used in conjunction with a mechanical thrombectomy device. When used alone, thrombolytic medications are most effective when infused directly into the thrombus. Thrombolytic therapy is covered in Chapter 2 on medications. There are a variety of thrombectomy devices which, in one way or another, fragment large thrombi into minute particles. Some of the devices fragment thrombi into particles that are similar in size to, or smaller than, blood cells, which allows the debris to circulate, while some of the devices also (attempt to) extract all (most of) the debris created by the fragmentation. Only one of the current devices that are available for the removal of thrombi from large vessels has a “distal protection” capability of capturing larger fragments that may be dislodged while the thrombus is being fragmented into micro particles or withdrawn. The original thrombectomy device was the fairly straightforward, Fogarty™ balloon (Edwards Lifesciences, Irvine, CA), which is very effective for extracting thrombi from peripheral vessels. The Fogarty™ device is a small balloon mounted at the distal end of a 4-French catheter similar to a very small Swan™ balloon (Edwards Life- sciences, Irvine, CA). The catheter with the balloon deflated is usually introduced into the thrombosed vessel by means of a cut-down on the vessel. The tip of the catheter with the balloon deflated is advanced past the thrombus. The balloon is inflated and the catheter is withdrawn from the vessel, which pulls the now trapped thrombus, which is adjacent to the catheter and proximal to (in front of) the balloon, back in the vessel. The trapped thrombus is withdrawn through the incision in the vessel or skin and out of the body. This is still an effective procedure for removing thrombi from peripheral vessels, although it has been supplemented by the use of thrombolytics and other more sophisticated thrombectomy devices. The simplest and one of the earliest and most readily available of the central thrombectomy devices was a catheter with suction applied to it 7 . Using the same prin- cipal, but using a long, large diameter (11–16-French) sheath instead of a catheter, makes this technique even more effective and very useful. When a small or fresh thrombus is detected within the vasculature, it can often be withdrawn from the intravascular site by positioning the tip of the large diameter sheath immediately adjacent to the thrombus and then applying a strong vacuum with a large volume (60+ ml) syringe to the proximal end of the sheath. This is frequently sufficient to suck a loose thrombus into the sheath. Large sheaths are readily available and usually require no additional (or expensive) equipment. Occasionally the thrombus must be fragmented or dislodged with a separate catheter, wire, or basket device. A basket retrieval device can be used to try to grasp the thrombus, but usually it tends to slice through the thrombus. Distal embolization is always a potential problem with this type of thrombus retrieval, but if performed expeditiously, can prevent significant further problems from very large thrombi. In addition to these improvised thrombectomy devices there is a variety of commercially manufactured devices. The Helix Clot Buster™ (ev3, Plymouth, MN) is a pneum- atic turbine driven impeller device that has been available for over a decade. The impeller has a rotating helical screw which is contained within a capsule at the distal tip CHAPTER 12 Foreign body removal 375 and rotates at 100,000 rpm. The rotating screw creates a very strong vortex of fluid, which macerates the thrombus into particles between 13 and 1000 microns in diameter. The capsule of the Helix Clot Buster™ device is 7-French and it is not introduced over a wire, which makes it more difficult to maneuver into more remote or tortuous locations unless it is introduced through a long pre-positioned sheath. There is no extraction system with the Helix Clot Buster™ with the result that it depends entirely upon all of the resultant fragments being small enough to pass through any distal capillary bed! This makes this device less desirable for use in the systemic arterial circulation. The Thrombex™ device (Edwards Lifesciences, Irvine, CA) is another rotating helical screw that macerates the thrombus, but it then aspirates the thrombus into an evacuation container. The Thrombex™ is mounted on a 6- French catheter, which makes it usable in smaller patients. Even with built-in aspiration of the debris, there is still a potential for some distal embolization. The AngioJet™ (Possis Medical, Inc., Minneapolis, MN) macerates the thrombus with multiple, extremely high- velocity jets of saline, which are directed backward from openings adjacent to the tip of the catheter. The high- velocity jets create a partial vacuum by a Bernoulli effect, which sucks the fragments out of the circulation through a separate lumen in the catheter. The extremely high velocity of the jets of saline macerates the thrombus very finely, and the very localized distribution of the jets allows the fragments to be withdrawn effectively from the circulation. AngioJet™ catheters are available in the 4-French XMI™, the 5-French XVG™, and the 6-French Xpeedior™, and they all pass over a wire, which makes them more versa- tile for entering precise locations and traversing thrombi in smaller vessels. AngioJet™ catheters can be used with a single-use pump set or with a fairly complex, multi-use drive unit. Because of the small size and the over-the-wire use of AngioJet™ catheters, these are the most suitable for smaller pediatric and congenital patients 8 . However, the drive unit, in addition to being fairly complex, is expensive and is usually not available in a purely pediatric/ congenital cardiac catheterization laboratory, unless the laboratory has some association with an adult cardiovascular service. The drive unit is mobile, so could be moved between co-operating and near-by laboratories. The AngioJet™ system and catheters can be used to infuse thrombolytics locally into the thrombus as part of the total thrombus removal procedure. The Oasis™ Thrombectomy Device (Boston Scientific, Natick, MA) has a single small nozzle at the tip of the catheter, which directs a high-velocity jet of saline back into the port of a separate lumen in the catheter. The high- velocity jet creates a Venturi effect, which fragments the thrombus while, at the same time, it sucks the fragments back into the catheter. As with the other devices without specific distal protection systems and although the particles are very small, particulate matter that is dislodged can embolize distally. The Trellis Infusion System™ (Bacchus Vascular Inc., Santa Clara, CA) utilized occlusion balloons in the lumen of the vessel above and below the thrombus to “contain” the debris. A catheter that rotated between the occlusion balloons macerated the clot into fine particulate matter, which, in turn, was evacuated from the area between the occlusion balloons. The rotating catheter tended to denude the endothelium of the vessel where it touched. When the area of the vessel could be isolated with the occlusion balloons, this device had one of the best chances of preventing distal embolization; as of this writing, however, the Trellis™ device has been withdrawn from the market. The Trerotola Percutaneous Thrombectomy Device™ (PTD) (Arrow International Inc., Reading, PA) is a self- expanding, 9 mm diameter, stainless steel, wire basket, which rotates at 3,000 rpm. The rotating basket fragments the clot into “macro” particles that are as large as 3 mm, but there is no evacuation system for these large fragments. The device can be delivered over a wire, which makes it easier to deliver to distal, more circuitous locations such as branch pulmonary arteries. The rotating basket denudes the wall of the adjacent vessel where it touches. The major disadvantage is the potentially larger resultant fragments. As the thrombus is being broken up, the area distal to the thrombectomy must be able to toler- ate the embolization of the larger fragments. Complications of foreign body retrieval/removal The removal of a foreign body is usually necessitated by an adverse event that can become a complication, but the retrieval procedure itself can create complications. As with all other complications, the best treatment is preventing their occurrence. The retrieval of all foreign bodies requires extensive manipulation of often large and stiff catheters and multiple exchanges of wires, sheaths, catheters and the retrieval devices themselves. All of these manipulations and exchanges carry the same, or even higher, risks of the complications that occur from the routine manipulation of any cardiac catheter. Meticulous attention to the details of normal catheterization pro- cedures for the manipulation of catheters, wires and sheaths, and the prevention of air and/or clot embolization are mandatory during every retrieval procedure. Each of the separate foreign body retrieval devices is associated with specific complications, which have been discussed previously in the discussions of each of the devices. Intravascular structures can be torn or perforated when a foreign body is pulled loose or withdrawn through a vessel. This occurs most frequently during intracardiac CHAPTER 12 Foreign body removal 376 lead extractions and is a known, half-anticipated, part of the procedure. It does occur, very rarely, with the forceful extraction of any foreign body that has become embedded in tissue and should always be anticipated. With the unex- pected or unexplained deterioration of a patient during any foreign body extraction a tear or perforation is always considered. The treatment is intensive medical support of the patient with the replacement of lost blood until surgical intervention is available to repair the tear. A foreign body becoming entangled in a ventricle or a cardiac valve is another complication of foreign body retrieval, which for the most part is iatrogenic and should be avoidable. Most dislodged devices (e.g. coils, occlusion devices, stents) in the systemic venous system embolize directly to the pulmonary artery or tumble through the ventricles into the pulmonary artery when they become dislodged during or after an implant. They become lodged in the ventricle when an attempt is made to withdraw a partially or totally exposed device through the ventricle during a retrieval procedure. Any foreign body that cannot be withdrawn completely into a sheath, should not be withdrawn through a ventricle. Avoiding this problem requires a difficult judgment decision before the foreign body is even grasped with a retrieval device. Once a large foreign body is grasped securely with a retrieval device, occasionally neither can it be withdrawn completely into a sheath nor can it be released from the retrieval device! The probability of this combined problem should always be considered before grasping a foreign body with a retrieval device when the foreign body must be withdrawn through a ventricle before its final extraction. When a large, catheter-delivered, intracardiac device becomes trapped in the right ventricle, it usually requires a sternotomy and cardiopulmonary bypass to remove the device, while a direct surgical retrieval from the pulmonary artery requires a thoracotomy, but usually does not require cardiopulmonary bypass. This should be considered before an attempt at grasping or withdrawing an exposed foreign body through a ventricle is even contemplated. Occasionally, a foreign body is loosened with a retrieval device, but before the foreign body can be withdrawn from the body it becomes released inadvertently or is lost back into the circulation. This results in the embolization of the device to another location. Unless the device embolizes to or through a ventricle, the inadvertent loss of the device usually does not result in any permanent sequelae, but does require a repeat retrieval procedure. Summary With the professional expertise which should be present in a well equipped pediatric/congenital catheterization laboratory, and using one or a combination of the retrieval systems described, the removal of virtually all intravascular foreign bodies is possible by a catheter technique. However, even with all of the latest equipment and the best techniques, there are a few circumstances when a foreign body cannot, or should not be removed by a transcatheter technique. This applies particularly to large and not easily compressible intracardiac therapeutic devices. Very large devices (large ASD devices, fully expanded intravascular stents) may not compress sufficiently or fold enough to be withdrawn even partially into even the largest, long sheath available. Persistent attempts at the removal of such devices, particularly if the foreign body must be withdrawn through a ventricle, have a high likelihood of causing significant and often permanent intravascular or intracardiac damage. In that circumstance, surgical assistance for the removal of the foreign body is needed. When a patient in whom a large or difficult-to-remove device has embolized must undergo cardiac surgery to correct the particular defect anyway, or there is some other major defect requiring surgery, there is little wis- dom or justification for pursuing an extensive transcatheter removal procedure unless the device is causing an immediate life-threatening problem. Subjecting the patient to the often long, complex, and potentially dangerous transcatheter removal procedure with its large dose of radiation is in no way justified when cardiac surgery is inevitable. This is true particularly when the original defect is not treatable by a similar or larger catheter- delivered device (e.g. an embolized ASD occlusion device in an unusually positioned or large ASD). It requires more skill, judgment and maturity on the part of the interventional cardiologist to determine when a foreign body is too difficult or dangerous to remove, and then to make the decision not to pursue the catheter retrieval any further. References 1. Dotter CT, Rosch J, and Bilbao MK. Transluminal extraction of catheter and guide fragments from the heart and great vessels; 29 collected cases. Am J Roentgenol Radium Ther Nucl Med 1971; 111(3): 467–472. 2. Lillehei CW, Bonnabeau RC Jr, and Grossling S. Removal of iatrogenic foreign bodies within cardiac chambers and great vessels. Circulation 1965; 32(5): 782–787. 3. Moncada R et al. Migratory traumatic cardiovascular foreign bodies. Circulation 1978; 57(1): 186–189. 4. Bracke FA, Meijer A, and Van Gelder B. Learning curve char- acteristics of pacing lead extraction with a laser sheath. Pacing Clin Electrophysiol 1998; 21(11 Pt 2): 2309–2313. CHAPTER 12 Foreign body removal 377 5. Fearnot NE et al. Intravascular lead extraction using locking stylets, sheaths, and other techniques. Pacing Clin Electrophysiol 1990; 13(12 Pt 2): 1864–1870. 6. Byrd CL et al. Intravascular lead extraction using locking stylets and sheaths. Pacing Clin Electrophysiol 1990; 13(12 Pt 2): 1871–1875. 7. Greenfield LJ, Kimmell GO, and McCurdy WC 3rd. Trans- venous removal of pulmonary emboli by vacuum-cup catheter technique. J Surg Res 1969; 9(6): 347–352. 8. Kirby WC, D’sa R, and Shapiro SR. Mechanical thrombectomy for treatment of postoperative venous obstruction in pediatric patients. J Invasive Cardiol 2004; 16(5/Suppl): S27–S29. 378 Rashkind™ Balloon Atrial Septostomy The Rashkind™ Balloon Atrial Septostomy (BAS), which was introduced in 1966, was the first intracardiac, non- surgical interventional procedure to be developed and used clinically 1 . The Rashkind™ BAS was not only the first procedure, but it was exceptionally innovative and daring for the timea and even for today. Dr William Rashkind devised the non-surgical technique for the creation of an atrial septal defect as a palliation for newborns with transposition of the great arteries at a time when transposition was one of the most lethal congenital heart defects. The Blalock–Hanlon surgical atrial septectomy was an alternative for the palliative creation of an atrial defect, however, in a critically ill infant, the surgical septectomy was associated with a high morbidity and mortal- ity in most centers at that time. The Rashkind™ BAS procedure, although “crude” by all standards, was dramatically and instantaneously successful, and has persisted until today with little change from the original technique as an essential procedure for many congenital heart lesions. Indications for a balloon atrial septostomy The need for an atrial septostomy is determined by the underlying cardiac lesion and from the associated clinical findings. Infants or older patients whose clinical signs or symptoms can be improved by better mixing or “venting” of the systemic venous or pulmonary venous blood are candidates for an atrial septostomy. Patients with transposition of the great arteries have parallel systemic and pulmonary circuits and benefit dramatically from mixing of their systemic and pulmonary venous blood at the atrial level. Patients with pulmonary atresia, tricuspid atresia, and other hypoplastic and poorly functioning right ventricles require an adequate interatrial communication to allow systemic venous blood to return back into the systemic arterial circuit. Patients with severe mitral stenosis, mitral atresia or other varieties of hypoplastic left ventricle represent an analogous situation, but for blood to flow in the opposite direction where it is trapped on the left or pulmonary venous side of the circulation. These hypoplastic left heart patients require an atrial septostomy to vent the pulmonary venous blood back into the functional systemic circulation. Patients with total anomalous pulmonary venous connection require an atrial opening to permit both the systemic and pulmonary venous blood to re-enter the systemic arterial circulation. The BAS is accomplished by forcefully pulling (“jerk- ing”) a small spherical balloon through an essentially intact atrial septum, thereby tearing an opening in it. The adequacy of the opening that is created depends upon the toughness of the septum, the size and compliance of the balloon used for the septostomy and the force with which the balloon is pulled through the septum. Hemodynamics of restrictive atrial septal communications The necessity for septostomy is suggested by an echocar- diogram with the demonstration of a patent foramen ovale or tiny atrial septal defect with restricted flow in a patient with any of the previously mentioned anatomic defects. The restrictive nature of the defect is confirmed in the catheterization laboratory by the pressure difference between the two atria or by angiography demonstrating restrictive flow, or minimal or no mixing at the atrial septal level. The difference in pressure will be very significant when the predominant flow of blood is, or should be, from left to right through the atrial defect. The left atrium is relatively non-compliant, and develops very high pressures when there is restriction to the outflow of the pulmonary venous blood from the left atrium. The right atrium, on the other hand, by itself and along with the hepatic veins and the connected total systemic venous “pool”, is very 13 Balloon atrial septostomy [...]... seen, the balloon is carefully and gently withdrawn toward, and fixed against, the intact interatrial septum during the remainder of the in ation to the desired volume As the balloon is in ated further, continued care is taken to prevent it from being sucked through the left A-V valve and into the ventricle This is avoided by maintaining gentle tension on the balloon and careful observation of its motion... limited in order not to pull the balloon into the hepatic veins/ ductus venosus During a balloon atrial septostomy procedure performed in the neonatal intensive care unit or the catheterization laboratory, an arterial monitoring line is desirable, and in our laboratory is considered essential In the newborn infant with congenital heart disease, the arterial line is often present as an umbilical artery line... mechanism in the left atrium Both the sheath and the blade catheter are maintained on a flush Occasionally, in a very small left atrium, the entire metal pod containing the blade does not fit all of the way into the left atrium and extends partially back through the septum into the right atrium In this case, the blade and the groove containing the blade also extend partially back through the septum, which, in. .. the cutting balloon is in ated to its maximum pressure/diameter in the atrial septum When in ated, the cutting balloon is moved slightly forward or backward over the wire within the opening to enhance the “incising” effect of its micro blades The cutting balloon is deflated, rotated slightly within the septal opening and the in ation–incision” repeated After at least two separate in ations–incisions... catheteraparticularly in small infants Once the second catheter has been introduced and advanced almost to the right atrium, the non-deflated septostomy balloon is withdrawn into the right atrial–inferior vena caval junction in order to stabilize the balloon in the side-to-side direction The septostomy balloon is pulled tightly into the inferior vena cava, which fixes it in a fairly stable, non-mobile,... atrial septum It was designed to create an incision in a resistant or tough atrial septum using the blade to initiate the creation of a larger opening in the septum The procedure and the unique blade catheter were developed by Dr Sang Park in collaboration with Cook Inc (Bloomington, IN) 1 For introduction into the heart, the blade is recessed in a metal housing or “pod” at the distal end of the catheter... still restrictive opening As the open blade is withdrawn through even a small preexisting opening, the blade, which is not particularly sharp, distorts (elongates) the pre-existing opening to conform to the linear shape of the blade The elongation of the septal opening allows the blade to pull through the atrial septal opening by merely stretching the pre-existing opening without incising the septal tissues... stretching rather than cutting and then tearing the atrial opening In older patients with a pre-existing small to moderate sized atrial communication but, at the same time, the preexisting defect is too small for adequate atrial mixing, the blade incision in the septum is performed through a separate transseptal atrial puncture that is at least 5 mm (or more) away from the original opening in the atrial... either a standard transseptal needle set or with a radiofrequency perforation catheter10 The transseptal puncture is performed 5 10 mm away from the pre-existing opening In order to create one larger opening, the new opening can be extended into the original opening by angling the blade toward the original opening during the blade pullthrough As an alternative, an entirely separate, second opening can... angiocardiogram In patients with left atrial to right atrial shunting, an injection is performed in a right upper pulmonary vein with recording in a 45 left anterior– oblique X-ray projection with cephalad angulation (i.e 4chambered view) In patients with predominately right to left shunt lesions, the angiocardiogram is performed with an injection into the right atrial–inferior vena cava junction, and recorded in . by maintaining gentle tension on the balloon and careful observation of its motion on fluoroscopy or echo during its initial positioning and entire in ation. The final positioning, the in ation. available in the 4-French XMI™, the 5- French XVG™, and the 6-French Xpeedior™, and they all pass over a wire, which makes them more versa- tile for entering precise locations and traversing thrombi in. communication ini- tially. With any pre-existing communication, the second end-hole catheter is maneuvered through the same opening and then into the same or even a separate left pulmonary vein and

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