Cardiac Catheterization in Congenital Heart Disease: Pediatric and Adult - Part 10 doc

CHAPTER 31 Purposeful vascular perforations 844 and to the valve. Valve perforations with each of these “instruments”, and from both approaches, occasionally were successful. Unfortunately, the force and “push” that were necessary to penetrate the valve, often pushed the supporting catheter, which contained the stiff needle and/or the retrograde wire, backwards and away from the plate-like valve rather than causing the perforating instrument to puncture the valve. When the guide or sup- port catheter was pushed away, it prevented the perfora- tion, or even worse, displaced the sharp instrument away from the center of the “plate-like” valve and into the perivalvular area. A puncture into the adjacent areas resulted in perforation into the pericardium and/or an adjacent chamber/vessel, often with catastrophic results. Experimental, and recently, clinical experience demon- strated the feasibility of “drilling” through tissue, and more specifically pulmonary valve tissue, with laser or radio-frequency (RF) energy. Both energy sources have demonstrated considerable success in penetrating the valve. When this is followed by a balloon dilation of the valve, very adequate pulmonary valve openings are achieved allowing unobstructed prograde blood flow into the pulmonary artery. The amount of this prograde flow then is dependent on the size of the tricuspid valve, the potential volume and the compliance of the right ventricle. Laser energy was the first energy source to be used in clinical trials in Europe 5–7 . The laser energy is delivered through a fine fiberoptic strand or “wire” to a very specific area, and proved very successful at perforating the atretic pulmonary valve in patients with pulmonary valve atre- sia by essentially vaporizing the tissue in front of the beam. The laser beam, unfortunately, also easily continues to perforate any tissues in its path beyond and/or adja- cent to the valve. The laser energy was successful at perforating an opening in the atretic pulmonary valve in approximately 80% of the small number of patients in whom it was tried initially. The opening allowed the pas- sage of a guide wire through the valve and subsequent dilation of the valve. Although successful in perforating the valve, the laser system has several disadvantages in addition to the poor controllability of the depth of penetration. The Excimer Laser™ generator is large and very expensive. Unless the particular pediatric cardiac catheterization laboratory works in conjunction with an adult catheterization labor- atory and/or performs many laser-assisted pacemaker lead extractions, the capital expense of the laser generator “just” for the very few pulmonary atresia patients who present to even large pediatric cardiac centers, cannot be justified easily. In addition to the ease of perforating unwanted structures within the heart with the laser, the intense laser energy also carries a risk of “stray” laser beams in the area of the patient, which can create retinal damage to the operators and other employees in the catheterization laboratory. As a consequence, all person- nel in the laboratory are required to wear special, some- what cumbersome, protective eye wear. The fiberoptic laser “wires” are expensive and finally, and absolutely the greatest deterrent to operators in the US until very recently: there was no laser “wire” that was approved for use outside of specific protocols in the United States. As an excellent alternative to laser energy, radio- frequency energy delivered through a very fine insulated wire can also be used to perforate atretic tissues, and the atretic pulmonary valve in particular. The RF energy is less powerful for perforating structures, but it is consider- ably more controllable than the laser energy. A radio- frequency generator for perforation is considerably less expensive and less complex than any laser generator. In addition, radio-frequency generators are commonly avail- able in pediatric and congenital catheterization labor- atories, where they are used for the ablation of abnormal intracardiac “electrical” conduction tracts. However, the current, and now standard RF “ablation” generator, which is low impedance and uses low-voltage (30–50 volts), high- power (30–50 watts) sustained (60–90 second) energy for the “ablation” of tissues without perforation, requires significant electrical modifications to convert the gener- ator into a high-impedance, high-voltage (150–180 volts), low-power (3–5 watts) and short-duration (1–2 second) energy generator, which is necessary for “perforation”. The special BMC Radio Frequency Perforation System™ (Baylis Medical Co. Inc., Montreal, Canada) is a generator that is designed and dedicated specially for “perforation”. The generator now is available commer- cially (even in the US) and is reasonably priced. This generator has built into it the necessary high-voltage, low-power and short-duration pulses of energy that are necessary to generate the high impedance necessary for perforation. A single use RF perforating “catheter” matched to the RF generator along with an “injection” coaxial catheter and a connecting cable are available as “perforating kits” to be used with the specific RF gener- ator. The total RF generator and the “catheter kit” are approved for “intravascular perforation”, even in the United States. The disposable “kit” consists of the Nykanen Radio Frequency Perforation Catheter™ and a special Coaxial Injectable Catheter™ (Baylis Medical Co. Inc., Montreal, Canada). The “perforation catheter” is a 0.024″, 265 cm long, teflon “catheter” tightly bound over a 0.016″ conduct- ance wire. Only the distal 1.5 mm and several mm of the proximal bare wire are exposed. The teflon over the wire provides an insulated coating to the wire and pro- duces a relatively stiff, “pushable” shaft for the combina- tion. The distal region of the “catheter” is flexible and can be bent or pre-formed into a specific curve for easier CHAPTER 31 Purposeful vascular perforations 845 maneuverability. This allows the perforating “catheter” to be maneuvered similarly to a fine torque-controlled guide wire. The proximal end of the teflon “catheter” has no “hub” but attaches to a removable connecting cable, which, in turn connects it to the generator. The “coaxial injectable catheters” are thin walled 0.035″ or 0.038″ dia- meter, 145 cm long catheters with a distal radio-opaque marker and a floppy, distal 10 cm tip. The inner diameters of the two catheters are 0.024″ and 0.027″, respectively. These catheters also have removable hubs so that the coaxial catheter and the contained perforation catheter together can act as a “thick guide wire” over which other catheters (balloon catheters) can be introduced. Technique for perforation of the pulmonary valve in patients with pulmonary atresia and intact ventricular septum The diagnosis of pulmonary atresia with or without a ventricular septal defect usually is made clinically in the newborn period with confirmation by echocardiographic evaluation. By the time these infants are seen by a cardi- ologist, they usually already are receiving prostaglandin to keep the ductus arteriosus open, and this provide the infants with some pulmonary flow. Rarely infants with pulmonary atresia and intact ventricular septum arrive in the catheterization laboratory at several months of age, having had a naturally persistent ductus arteriosus and/ or a previously created systemic to pulmonary artery surgical shunt as palliation. As opposed to patients with pulmonary atresia and an intact ventricular septum, patients with pulmonary valve atresia and a ventricular septal defect often have extensive systemic to pulmonary collateral flow to the lungs and/or, occasionally, a large persistent patent ductus arteriosus and, as a consequence, these patients can survive to an older age with no prior intervention. A cardiac catheterization laboratory that has very high- quality, biplane X-ray imaging and angulation capabilit- ies for the X-ray tubes, is necessary for these perforation procedures. Because of the precarious nature of these infants, the extensive catheter manipulation required and the potential for inadvertent occlusion of the ductus arter- iosus during the procedure, these infants are intubated and ventilated before starting the catheterization. Any patient in whom a purposeful perforation is considered, is type and cross-matched for one or two units of fresh whole blood. If the replacement of blood becomes neces- sary, the clotting factors as well as the oxygen carrying capacity of whole blood are desirable. When an RF perfora- tion is anticipated, a large “grounding plate” is placed under the back of the patient at the very beginning of the procedure. The grounding plate is attached to the RF generator via the conductive cable as the patient is being positioned on the catheterization table. Percutaneous access to at least one femoral vein and a femoral artery is established. In the catheterization laboratory, the diagnosis is con- firmed and the details of the right ventricular and pul- monary artery anatomy are defined with selective biplane right ventricular (outflow tract!) and aortic angiography. The angiograms not only define the anatomy of the valve, but demonstrate any right ventricular to coronary artery fistulae in patients with pulmonary atresia with an intact ventricular septum. In these patients, who usually do have a good pulmonary artery in the presence of coronary artery to RV fistulae, a right ventricular (RV) dependent coronary circulation must be excluded before valve perfora- tion is considered. The laser or RF techniques for valve perforation also are used in patients with pulmonary atre- sia and a ventricular septal defect, but only when there is a well-developed main pulmonary artery and the RF catheter/wire or laser wire, which is advanced from the ventricle, can be advanced into the right ventricular infundibulum and supported exactly at and against the “valve” area. Whether using laser (which has only recently become available in the US) or RF energy, the techniques for pulmonary valve perforation are similar. Radio-frequency perforation of the pulmonary valve from the right ventricular approach in patients with pulmonary atresia and intact ventricular septum The technique for pulmonary valve perforation using the radio-frequency perforating system, which is designed specifically for RF tissue perforation and is available around the world (even in the United States), is described in detail in this chapter. In addition to quality, biplane angiograms in the right ventricular outflow tract, a biplane angiogram of the main pulmonary artery is neces- sary to visualize the valve annulus from the pulmonary side. It is desirable to position a catheter in the main pul- monary artery against the pulmonary side of the atretic pulmonary valve. The catheter in the pulmonary artery is introduced retrograde and passed into the pulmonary artery through either the patent ductus arteriosus or a pre- viously placed shunt. The ductus in the newborn, and par- ticularly when the infant is on prostaglandins, is very “mushy”, friable and often tortuous. Force never should be used in crossing the ductus. If the ductus cannot be crossed readily and almost inadvertently, a biplane aorto- gram is performed in the descending aorta with the injection of contrast immediately adjacent and/or slightly distal to the aortic end of the ductus. This aortogram will determine the exact course of the ductus and will define the pulmonary artery/pulmonary valve more precisely. Occasionally, even with the course of the ductus clearly CHAPTER 31 Purposeful vascular perforations 846 defined, it is necessary first to cross the ductus with a small, soft tipped, torque-controlled wire and then to advance a multipurpose angiographic catheter over this wire into the pulmonary artery. The catheter itself in the pulmonary artery serves as a constant “target” during the perforation from the right ventricle, and is used for repeated angiography in the pulmonary artery during the perforation. If a catheter cannot be placed in the pulmonary artery, at the very least there must be some capability of obtain- ing repeated, good quality, biplane angiographic imaging of the main pulmonary artery/pulmonary valve. When the pulmonary artery cannot be entered reasonably, the pul- monary artery imaging is obtained from the contrast injected in the aorta and the flow through the ductus, through a previous shunt or through collaterals. The tip of the angiographic catheter for these injections in the aorta is maintained immediately adjacent to or actually in the origin of the vessel(s) providing the pulmonary flow in order that the maximum contrast reaches the pulmonary artery with each injection. In the very rare instance where there is no demonstrable systemic to pulmonary artery flow, the biplane imaging of the pulmonary artery is obtained from a biplane pul- monary vein wedge angiocardiogram. This technique is satisfactory only if the main pulmonary artery can be visu- alized adequately and repeatedly by this technique. The use of repeated pulmonary vein wedge angiograms to visualize the pulmonary arteries requires the presence of an additional venous catheter situated in the vein wedge position throughout the entire perforation procedure. Biplane “freeze frame” images from the right ventricu- lar angiogram, which demonstrate the right ventricular outflow and the atretic pulmonary valve areas most satis- factorily, are displayed as “road maps” for the subsequent catheter positioning. After the pulmonary artery is visual- ized angiographically and/or the retrograde catheter is placed in the pulmonary artery adjacent to the pulmonary valve, a 4- or 5-French, pre-shaped “right coronary” or “cobra” guiding catheter is advanced into the right vent- ricle and manipulated very carefully and precisely into the right ventricular outflow tract (RVOT). This “guiding” catheter is maneuvered until it is against the center of the atretic valve in the right ventricular outflow tract. The specific guiding catheter that is used depends upon the size and, particularly, the right ventricular anatomy of each individual patient. The angle at the tip of the parti- cular guiding catheter, which is positioned in the RVOT, should point the tip of the catheter directly at the other catheter in the pulmonary artery and/or at the center of the atretic valve in both the PA and lateral views as seen on previous angiograms. Several different shaped guiding catheters often must be tried in order to position the tip of the guiding catheter pointing precisely in the exact direction in both X-ray planes. As much time and effort is taken as is necessary to achieve this precise positioning before proceeding with the perforation. Any misalign- ment in either plane very likely will result in perforation out of the vascular channels and into the pericardium. When the right ventricular catheter tip appears to be in the ideal, proper position, a repeat, small, not too forceful, hand injected, biplane angiocardiogram is performed through this catheter. This angiogram demonstrates the outflow tract and valve even better and illustrates clearly any distortion to the area created by the catheter itself. When the tip of the catheter is aligned precisely, these images are displayed as the new “road map”. If none of the available pre-shaped guiding catheters can be positioned precisely in a direct line to, and against, the valve, the guiding catheter is withdrawn. The tip of the catheter is softened by immersing it in sterile, boiling water. Once softened, a different, more appropriate curve is formed at the tip. After reshaping the guiding catheter, it is reintroduced and positioned properly against the valve. Alternatively or in addition, a Mullins™ deflector wire outside of the body is pre-shaped with very smooth curves to correspond to the desired course from the right atrium, to the right ventricle, to the right ventricular infundibu- lum and finally against the atretic valve. All of the bends on the wire are formed “tighter” than the existing curves through the right heart to allow for some straightening of the wire as it passes within the guiding catheter. When a Mullins™ wire is used to hold the guiding catheter tip in place, the guiding catheter must be at least one French size larger in order to accommodate both the Mullins™ wire and the perforating catheter side by side within the lumen of the guiding catheter. The Mullins™ wire is introduced into the pre-shaped and previously positioned catheter through a Tuohy™/ side port back-bleed valve. The wire is advanced within the catheter to a position just within the distal tip of the catheter. The purpose of the Mullins™ wire is to redirect and maintain the guiding catheter in its position against, and pointing directly at, the center of the atretic valve while the perforating wire/catheter is introduced. Again, it is even more important that once this considerably stiffer combination is positioned against the valve a re- peat small biplane angiogram is performed through the guiding catheter to demonstrate any further distortion of the area. Once the catheters are in place, preferably on both sides of the valve, the RF perforation catheter, which has been advanced through the BMC coaxial catheter while they still are outside of the body, is introduced into the guiding catheter that is pre-positioned in the right ventricular outflow tract against the atretic valve. The perforating/ coaxial catheter is introduced through a wire back-bleed flush valve or a Tuohy™ side port adaptor attached to the CHAPTER 31 Purposeful vascular perforations 847 hub of the guiding catheter. Otherwise, with the sig- nificantly larger lumen of the guiding catheter than the diameter of the perforating/coaxial catheter and with the high pressure in the right ventricle, there will be significant bleeding into and externally out of the catheter around the perforating catheter through the hub of the guiding catheter. The guiding catheter is cleared of blood by allowing it to bleed back passively through the Tuohy™ valve and then placed on a continuous flush. Any blood that remains in the catheter can clot, and potenti- ally represents an embolus. The Tuohy™ type side port adaptor also allows contrast injections through the side port into the guiding catheter and around the perforat- ing/coaxial catheters. If a Mullins™ wire is used to sup- port the guiding catheter, a second Tuohy™ side port valve is “piggy-backed” onto the angled side port of the first Tuohy™. The R-F wire is passed through the first Tuohy™ adaptor, which is attached directly to the guide catheter. The Mullins™ wire is introduced through the second Tuohy™ valve, which is attached to the angled port of the first Tuohy™. The perforating catheter, which is within the coaxial catheter, is advanced to the tip of the guiding catheter. An alternative technique in a small, very tight RVOT is to introduce only the “perforation catheter” into the guiding catheter without the covering coaxial catheter. The “perfor- ating catheter” alone is more flexible and causes less dis- placement of the precisely positioned guiding catheter. In this circumstance, the coaxial catheter can be introduced and advanced over the perforating catheter after the valve has been perforated. Once the perforation catheter is in the RVOT at the tip of the pre-positioned guiding catheter, a repeat biplane angiogram of the RVOT/pulmonary valve is performed to verify that the catheter in the RVOT is still pointing exactly at the center of the pulmonary valve. If the tip of the guiding catheter is displaced at all away from the center of the atretic valve, the guiding catheter with the contained perforating catheter is read- justed by very slight torque and/or to-and-fro motion. The biplane angiogram is repeated to verify the exact rela- tionships after any readjustment. When the tip of the guiding catheter is in position and pointing in the precise direction, the proximal end of the wire of the perforation catheter is attached to the genera- tor with the BMC™ connecting cable. The tip of the RF perforation catheter is advanced just barely out of the tip of the guiding catheter and into the tissue of the atretic valve. The flush on the side port of the catheter is stopped. The generator is set for a one second duration and 5 watts power. While continuously observing the tip of the per- forating catheter on biplane stored fluoroscopy or slow frame rate biplane cine angiography, a single burst of RF energy is delivered while simultaneously holding, but not advancing, the tip of the perforating catheter against the valve. Usually this is sufficient for the perforating catheter to pass through the valve into the pulmonary artery. If not, the positioning of the guide and perforating catheter tips is rechecked on biplane fluoroscopy. If the positions are still not ideal, the perforating catheter is withdrawn within the tip of the guiding catheter while the guiding catheter repositioned. When the guiding catheter is in the exact position, the perforating catheter tip is re-advanced into the valve tissues. When both catheters are in the pre- cise position, the RF energy is reapplied to the perforating catheter while again holding the tip of the perforating catheter against the valve without pushing forcefully. This process is repeated until the perforating catheter advances through the valve “plate” and into a “free” position within the pulmonary artery just beyond the valve while no energy is being applied. Any advancing of the tip of the perforating catheter within the pulmonary artery must be with no energy applied, as any RF energy applied to the tip will allow the tip to perforate any structure (wall!) in its vicinity! The exact position of the tip of the perforating catheter in the pulmonary artery is verified with a biplane pulmonary artery angiogram before proceeding further. Once the tip of the perforating catheter has entered the pulmonary artery freely, the perforating catheter is advanced with no energy applied as far as possible distally into the branch pulmonary artery or through the patent ductus into the descending aorta. When the perforating catheter is well into the pulmonary artery or the descend- ing aorta, the coaxial catheter is advanced over the per- forating catheter to the tip of the perforating catheter. The subsequent maneuvers depend upon the associated anatomy and the position of the perforating/coaxial cath- eters after they are advanced following the perforation. If the perforating/coaxial catheters pass into the descending aorta, together they are snared there with a snare catheter, which is introduced retrograde from the femoral artery. With traction held on the perforating/ coaxial catheter with the snare catheter, the guide catheter is removed from the femoral vein over the combined per- forating/coaxial catheter and replaced with a 2–4 mm diameter low-profile dilation balloon. When passed over the combined perforating/coaxial catheter, this requires a balloon catheter with a catheter lumen that will accommo- date a 0.035″ guide wire. An alternative technique, when the perforating/coaxial catheters pass into the descending aorta, is to withdraw the perforating catheter from the coaxial catheter and exchange it for a stiff 0.014″ or 0.016″ exchange length “coronary” guide wire. This exchange of the perforating catheter for wire is performed while the guiding catheter still is in position in the RVOT and the snare is around and gripping the coaxial catheter loosely. If the coaxial catheter begins to withdraw or buckle while the new, stiffer wire is introduced into it, the distal end of the coaxial catheter is grasped firmly with the snare in the CHAPTER 31 Purposeful vascular perforations 848 descending aorta. This supports the passage of the stiffer exchange guide wire through the relatively flimsy coaxial catheter as it passes through the tortuous course from the inferior vena cava through the right heart, pulmonary artery and ductus to the descending aorta. Once the stiffer, smaller exchange wire emerges from the tip of the coaxial catheter in the descending aorta, this wire alone is grasped securely with the retrograde snare. The snared distal end is withdrawn into the femoral area or even out through the femoral artery sheath. Either way, a very secure “through-and-through” or “rail” wire sys- tem is created. The coaxial and the guiding catheters are removed over the fixed wire. The through-and-through wire allows simultaneous strong traction from the two ends of the wire which, in turn, allows a very forceful for- ward push on the balloon dilation catheter without the catheter and/or the wire buckling in the right ventricle as the balloon passes through the tight valve. With the trac- tion applied at both ends of the exchange wire, the very low profile 2–4 mm diameter coronary balloon is passed over the wire and advanced through the “plate” of the pul- monary valve to initiate a sequential dilation of the valve. After the dilation with the initial, small coronary bal- loon, the balloon is exchanged over the same “rail” wire for a larger dilating balloon. Dilation balloons of progres- sively increasing size are used until a balloon that is appropriate in diameter for a single balloon pulmonary valve dilation of the particular valve annulus can be introduced. An alternative technique, which can be used when there is a patent ductus that can be traversed easily, is to posi- tion a retrograde snare catheter instead of an angiographic catheter in the pulmonary artery before and during the actual perforation of the valve. Instead of maneuvering the original retrograde angiographic catheter into the pul- monary artery, a 4-French Microvena™ snare catheter is passed retrograde through the patent ductus into the pul- monary artery. The standard snare catheter often is easier and safer to position in the pulmonary artery than an angiographic catheter. A floppy, soft tipped, torque- controlled wire is advanced totally atraumatically from the aorta through the ductus and against the atretic pul- monary valve. The end-hole snare catheter then advances easily over this previously positioned wire. A small 5 or 10 mm diameter snare (depending upon the diameter of the pulmonary annulus) is opened in the annulus of the pul- monary valve on the main pulmonary artery side of the valve. The properly sized snare aligns perpendicular to the long axis of the pulmonary artery, around and outlin- ing the circumference of the valve annulus. The “circle” of the snare serves as a very clear “target” for the perforation with the RF catheter. As soon as the RF catheter with the coaxial catheter has advanced through the valve tissue, the perforating catheter also will be through the loop of the snare in the pulmonary artery! If there is any difficulty passing the coaxial catheter along with the RF perforating catheter through the new “puncture”, the RF perforating catheter alone can be advanced through the valve and grasped with the snare. Once the RF catheter is snared securely, traction is placed on the RF catheter and the coaxial catheter is drawn into the descending aorta with the snare. Either the coaxial catheter or a balloon dilation catheter is advanced over this fixed RF catheter and through the valve as described previously. If a retrograde angiographic catheter is positioned from the aorta, through the ductus and into the pulmonary artery, and the perforating catheter is not manipulated on its own from the pulmonary artery through the ductus into the descending aorta after the perforation of the valve, the retrograde angiographic catheter in the pul- monary artery is replaced with a snare catheter. Again, because of the frequent tortuosity and “mushy” nature of the ductus in these patients, the ductus is crossed with a very soft tipped torque wire and the snare catheter is advanced through the ductus over this wire. Once the snare is open in the main pulmonary artery, the perforat- ing wire/catheter almost automatically will be through the loop of the snare! The perforating catheter is grasped with the snare in the pulmonary artery and withdrawn into the descending aorta through the ductus, as described above. The worst-case scenario is when there is no patent duc- tus, or when present, the ductus cannot be crossed from either direction. In that case, the perforating catheter, immediately after perforating the valve, is manipulated as far as possible into a distal right or left branch pulmonary artery. With the guiding catheter still positioned in the RVOT and forced against the pulmonary valve over the perforating catheter, the coaxial catheter is advanced over the perforating catheter, through the valve and to the tip of the perforating catheter/wire. With the guiding and coaxial catheters both fixed in these positions, the perforat- ing catheter/wire is withdrawn carefully and replaced with a 0.014–0.018″ (depending upon which coronary dilation balloons are available) stiff, exchange length, “coronary” guide wire. The guide wire is advanced out of the tip of the coaxial catheter until the long floppy tip of the guide wire is “balled up” completely in a distal pul- monary artery branch. This “wadding up” of the floppy tip is essential in order to ensure that the stiff portion of the guide wire will be across the valve and well out into the branch pulmonary artery. Once the stiffer exchange guide wire is in this secure position in the distal pulmonary artery, the guide catheter and then the coaxial catheter are removed over the guide wire and replaced with a very low-profile, 2–3 mm dia- meter, “coronary” dilation balloon. Occasionally, even the very low-profile balloon will not follow over the wire through the thick valve tissue. In that circumstance, the CHAPTER 31 Purposeful vascular perforations 849 balloon is withdrawn over the wire and replaced with a larger guiding catheter that can accommodate the low- profile balloon. The guiding catheter is manipulated very gingerly over the wire through the right ventricle and up against the pulmonary valve. With the guiding catheter as an additional support, the low-profile balloon is passed over the wire, through the guiding catheter and through the valve. The sequential dilation of the valve is started over this wire. Once the “waist” in the initial balloon has been elim- inated, the balloon is removed over the wire and replaced with a slightly larger, 3–5 mm balloon. The balloons are replaced sequentially until a balloon is introduced that is appropriate in size for a single-balloon valve dilation, according to the annulus diameter of the pulmonary valve. Occasionally, the initial smaller wire must be ex- changed for a larger and stiffer wire to support the larger balloons, which will not pass through the guiding catheter. Laser technique for perforation of the pulmonary valve in pulmonary atresia with intact ventricular septumCfrom the right ventricular approach Excimer Laser™ energy has been used for the perforation of the atretic pulmonary valve outside of the United States for over a decade, but the lack of a small laser catheter approved by the US FDA precluded its use in the US until recently 6,7 . The Excimer Laser uses ultraviolet light with a wavelength of 308 nm to ablate tissues in the path of the laser light. The laser energy is generated with a VCX-300 Excimer Laser System (Spectranetics, Colorado Springs, CO), which often is available in an interventional catheter- ization laboratory for laser lead extractions. The recent approval by the US FDA of the Point 9™ Extreme Excimer Laser catheter (Spectranetics, Colorado Springs, CO) for the treatment of total occlusions of peripheral and coron- ary arteries in humans has made this very small laser catheter available for use for selected congenital lesions in the US. The Point 9™ Laser catheter is a 0.9 mm diameter, fairly flexible catheter, consisting of multiple layers of optical fiber strands, which run the length of the catheter and through which the laser energy is delivered. The bun- dled fibers surround an open lumen, which accepts a 0.014″ wire. The Point 9™ Laser catheter is advanced to the atretic pulmonary valve through a pre-positioned guiding catheter that has a lumen of at least 1 mm (3-French) dia- meter. The specific guide catheter that is optimal for the particular patient varies with the size and anatomy of each individual patient. The guide catheter should have pre- formed curves at the distal end that correspond to the course from the inflow to the outflow of the particular right ventricle. The guide catheter is maneuvered into the narrow outflow tract of the right ventricle to a position as close to the center of the “plate” of the atretic valve as pos- sible. The Point 9™ Laser catheter is delivered over a stiff 0.014″ guide wire with a fine floppy tip as well as through the guiding catheter. The floppy tip of the guide wire extends beyond the tip of the laser catheter and often loops back on itself in the right ventricular outflow tract as the Point 9™ catheter is maneuvered to the atretic valve. As the tip of the Point 9™ catheter approaches the valve, the wire is withdrawn into the laser catheter. Once positioned against the “plate” of the valve, 45 microJoules, at 15 kV and 25 Hz, of laser energy are deliv- ered through the catheter in one second bursts. The tip of the catheter usually passes through the atretic tissue with 1 or 2 bursts of energy with each burst penetrating approximately 100 microns. If there is any forward push applied to the catheter during the delivery of the energy, the laser catheter will continue through any tissue in front of it including out of the vascular space! Once the tip of the laser catheter has advanced through the atretic tissue into the main pulmonary artery, the guide wire is advanced out of the catheter and preferably into the descending aorta through the ductus. Once the wire is successfully through the “valve” the remainder of the procedure is identical to the procedure using RF energy. Laser energy has the disadvantages of requiring a large and expensive generator, which may not be available in all congenital heart catheterization laboratories, and the potential of retinal injury to surrounding personnel from the “scatter” of the high-intensity ultraviolet light. Until more experience shows a distinct advantage of laser over RF energy, the RF systems now appear preferable for pul- monary valve perforation in congenital heart lesions. Technique for perforation of the pulmonary valve in pulmonary atresia with intact ventricular septum retrograde through the patent ductus from the pulmonary arterial approach When there is significant difficulty or even the absolute impossibility of positioning the guiding catheter properly in the right ventricular outflow tract (RVOT) and/or there also is an easily crossed patent ductus, the perforation of the pulmonary valve in patients with pulmonary atresia with intact ventricular septum can be performed from the pulmonary artery side of the valve using a retrograde approach through the ductus 9 . Before the availability of the current and safer “burning” techniques to perform the perforation, stiff wires in association with the use of “brute force” had been used to push through the atretic pulmonary valves into the right ventricular outflow tract from the pulmonary artery approach. Because the “tar- get” area of the right ventricular outflow tract is small and CHAPTER 31 Purposeful vascular perforations 850 very narrow, the strong force (push), which necessarily had to be applied to the retrograde catheter, could easily displace the direction of the catheter tip with the result that this technique had a very high likelihood of perfora- tion into the pericardium instead of into the right vent- ricle. The retrograde perforation of the pulmonary valve is far more reasonable with the availability of RF wires and RF energy for the perforation. When the guiding catheter cannot be positioned in the RVOT with the tip of the catheter directed precisely at the valve in both X-ray planes, the retrograde approach for perforating the valve should be considered. The retro- grade perforation still requires that a catheter is posi- tioned in the RVOT for the purpose of performing selective biplane angiography even if the catheter cannot be directed precisely at the valve. The RVOT must be visu- alized very clearly, precisely and repeatedly with biplane imaging during a retrograde perforation. The right ven- tricular outflow tract usually tapers to a very fine tip or point just below the atretic valve. As a consequence, the RVOT presents a much smaller “target” when perforating from the pulmonary artery toward the RVOT. With a prograde venous catheter positioned in the RVOT, a Swan™ floating balloon catheter (Arrow International Inc., Reading, PA) is introduced retrograde into the femoral artery and advanced retrograde through the patent ductus and into the pulmonary artery with or without a pre-positioned floppy tipped wire through the ductus. With some retrograde “push” applied to the Swan™ catheter, the balloon is inflated in the main pul- monary artery directly in the pulmonary valve annulus and against the atretic valve. The inflated balloon in con- junction with the usual course through the ductus usually orients the lumen of the Swan™ catheter parallel to the long axis of the pulmonary artery and also often points the end hole of the Swan™ catheter directly toward the blind RVOT. The precise direction of the tip of the catheter that is seated in the atretic pulmonary valve is changed in order to point the lumen exactly toward the RVOT by varying the amount of “push” and/or torque on the Swan™ catheter. When the tip of the Swan™ catheter is pointing in the exact direction, the RF perforating wire/catheter is advanced through the Swan™ catheter to its tip, until the RF perforating wire is positioned against the atretic pulmonary valve. The relative relationships of the tip of the Swan™ and the RF catheter to the RVOT are verified with a small selective biplane angiocardiogram in the RVOT. The angle of the Swan™ catheter/perforating catheter together also can be adjusted slightly by minimal to-and-fro motion on the shaft of the Swan™ catheter while the perforating catheter is passing through it. When the tip of the Swan™ catheter/perforating wire/catheter is “aimed” exactly at the small, blind RVOT, the RF perfo- rating wire/catheter is advanced until the tip of the wire is embedded in the “valve” tissue. The position is rechecked with a repeat small selective biplane angio- cardiogram in the RVOT, and adjustments to align the Swan™ catheter again are made as necessary. Since the RVOT “target” is so small, perforation from the retro- grade approach is not attempted unless the perforating wire/catheter tip and the narrow RVOT are aligned exactly. When the RF perforating wire/catheter is point- ing precisely at the RVOT, and only then, is the RF energy applied while the perforating wire/catheter is held in the valve adjacent to the small RVOT. Instead of the retrograde Swan™ catheter, a pre- formed, end-hole only catheter can be used for the retro- grade perforation. The tip of a non-Swan™ type catheter is harder to keep exactly aligned in the center of the pul- monary valve on the pulmonary side of the atretic valve. This can be accomplished eventually with patience and often multiple exchanges of catheters with different curves at the tip. Once the perforation wire/catheter is through the atretic pulmonary valve and free in the RVOT, a 5 or 10 mm Microvena™ snare wire is introduced through the catheter in the RVOT and the tip of the perforating wire/catheter snared in that location. Occasionally, in very small infants, only the perforating wire without the covering “coaxial catheter” can be passed through the lumen of a small Swan™ catheter. In that circumstance the RF perforating wire alone is advanced through the valve after the perforation and grasped with the snare in the RVOT. If possible, the snared wire and/or catheter is withdrawn through the ventricle and tricuspid valve and exteriorized through the femoral vein but, once the per- forating wire/catheter is held securely, the Swan™ bal- loon catheter is withdrawn from the femoral artery over the proximal end of the perforating wire/catheter and is replaced over the perforating wire/catheter with either the coaxial catheter or a 4-French, multipurpose, end-hole catheter with a tapered tip. This step is unnecessary if the original retrograde catheter for the perforation was a non- Swan™ end-hole catheter. With traction held on the tip of the perforating wire/catheter in the right ventricle with the snare catheter, the coaxial or tapered end-hole catheter is advanced over the perforating wire/catheter, retro- grade through the ductus and then push–pulled across the pulmonary valve using traction at both ends of the perforating wire/catheter. Once the end-hole, retrograde catheter is in the RV, the snare around the wire is loosened enough to allow the catheter to pass over the perforating wire/catheter and through the snare. The perforating wire/catheter is withdrawn out of the femoral artery catheter and replaced with a floppy tipped, exchange length wire. If necessary during this exchange, the snare is tightened over the end-hole catheter that is passing through the pulmonary valve to hold the catheter in place. CHAPTER 31 Purposeful vascular perforations 851 Snaring the distal end of the catheter in the RVOT sup- ports the retrograde passage of the stiffer exchange wire through the ductus, the pulmonary artery, the perforated pulmonary valve and into the right ventricle. Once the tip of the exchange wire is through the valve and in the right ventricle, the floppy tip of the wire is grasped in the right ventricle with the snare and the com- bination wire and catheter is pulled back, and very care- fully through the tricuspid valve. Extra care is taken not to catch on the tricuspid valve structures and/or to pull too vigorously through the tricuspid valve. If the combination cannot be pulled easily through the valve, the snare is opened, releasing the grip on the wire. The retrograde catheter is withdrawn partially off the tip of the wire and back toward the pulmonary valve. The floppy tip of the wire alone is re-grasped with the snare, which is still within the right ventricle, and a repeat attempt is made to withdraw the snare catheter with the grasped retro- grade wire back through the tricuspid valve and into the right atrium. If the snare/wire still catches on the tricuspid valve, the wire is released from the snare and the snare loop with- drawn completely into the snare catheter. The snare catheter is withdrawn into the right atrium. A very careful attempt then is made at manipulating the retrograde catheter/wire, which is passing through the pulmonary valve, through the tricuspid valve and back into the right atrium. The catheter may “bind” in the thick, tight pul- monary valve structure and care must be taken to prevent it from buckling and pulling out of the recently perforated valve! If the wire is maneuvered to the right atrium, the tip of the wire is re-snared in the right atrium. If the wire/catheter cannot be maneuvered back to the right atrium, the snare catheter is manipulated through a different area of the tricuspid valve and back into the right ventricle, and/or an end-hole Swan™ balloon catheter is introduced from the femoral vein and used to cross the tri- cuspid valve into the right ventricle from the right atrium and then the Swan™ catheter is used as the snare delivery catheter. When an inflated Swan™ balloon advances across the small tricuspid valve, there is a better chance that the balloon will pass through the largest orifice of the tricuspid valve, and the snare wire can be used through the Swan™ catheter. The small size of the hypoplastic tri- cuspid valve and/or the tricuspid valve regurgitation, however, may prevent a Swan™ balloon catheter from “floating” into the right ventricle. Once the floppy tip of the wire is grasped with the snare in the right ventricle with either catheter that has passed through a different area of the tricuspid valve, the retro- grade exchange wire is pulled carefully into the right atrium. From the right atrium, the exchange wire is exteriorized through the femoral vein sheath, creating a through-and-through femoral vein to femoral artery wire. The remainder of the procedure is the same as when the perforation of the atretic pulmonary valve was from the prograde approach. Sequential dilations of the pul- monary valve are accomplished introducing the dilation balloons from the femoral vein over the through-and- through wire, as described previously. Once the pulmonary valve is open and there is pro- grade access to the pulmonary artery, the necessity for further palliation of the patient in the catheterization lab- oratory during the same procedure is determined in the laboratory at that time. Following a perforation and dila- tion of the pulmonary valve in patients with pulmonary atresia and intact ventricular septum, there almost always is a question about the adequacy of the right ventricular volume and the need for a systemic to pulmonary shunt and/or an atrial septostomy. These patients usually were dependent upon the patent ductus for most of the pul- monary flow and all have an existing patent foramen ovale/atrial septal defect; however, usually one or both of these sources of blood flow is/are inadequate. Once the infant stabilizes after the valve perforation/ dilation and there is adequate pulmonary flow, then fur- ther clinical assessment determines the need for an atrial septostomy. In the presence of a very small right ventricu- lar cavity and/or persistent very high right ventricular end diastolic and/or systolic pressures, the right ventricle often is not capable of accommodating an adequate dias- tolic volume from the systemic venous blood return. The resultant small right ventricular systolic volume then will be inadequate to provide enough forward blood flow through the lungs to the left heart to sustain an adequate systemic output. In the absence of an adequate opening or “vent” at the atrial level, the systemic venous blood pools in the systemic venous vascular bed and right atrium, the right atrium becomes massively dilated with the systemic venous return, and the cardiac output remains low. When this occurs acutely in the catheterization laboratory, a bal- loon or blade and balloon atrial septostomy is performed during the same catheterization. At the same time, when the patient does have even a marginal systemic cardiac output without significant right atrial/hepatic congestion after the pulmonary valve perforation, atrial septostomy is not performed during the initial catheterization. Some elevation of the right atrial pressure may augment the right ventricular filling of these small ventricles. When an atrial septostomy is performed, it lowers the right atrial pressure, and in turn, may compromise right ventricular filling! By eliminating this extra filling pressure and volume, the potential growth of the right ventricle also may be compromised. The balloon or a blade/balloon atrial septostomy always can be performed hours, days or weeks later if the sys- temic output decreases and/or the right atrium and liver become distended. CHAPTER 31 Purposeful vascular perforations 852 In addition to the question of adequate return of the sys- temic venous blood to the systemic output, the adequacy of the net pulmonary flow is assessed before the infant leaves the catheterization laboratory. After the valve has been opened successfully, the adequacy of the forward flow through the opened valve, the effect of the pul- monary regurgitation on the net forward flow and how much of the pulmonary flow still is from the ductus are determined from the angiograms. If a catheter interven- tion to increase the pulmonary flow is even considered, a catheter is advanced either prograde or retrograde across the ductus, prostaglandin is stopped and the infant observed in the laboratory for 30 minutes or longer. When the ductus remains patent after the prostaglandin has been stopped, no further intervention is considered at that time. When the ductus patency and flow are prostaglandin dependent, the 30 minutes usually are sufficient time for the prostaglandin effect to wear off and for the ductus to close functionally. When the net pro- grade pulmonary flow is insufficient after the ductus closes, the infant will become significantly desaturated and/or hypoxic. The choices at that time are to restart prostaglandin and terminate the case with plans for a sub- sequent surgical shunt or to consider the implant of a stent in the patent ductus arteriosus as a means of establishing a more permanent systemic to pulmonary artery “shunt”. With the newer, pre-mounted, flexible, small stents this is a much more viable option. The technical details of the atrial septostomy proced- ures are discussed in Chapters 13 and 14 and the tech- nique for stenting the patent ductus are discussed in Chapter 25. Until far more definitive data are available about which ventricles grow after the pulmonary valve is open and which patients have adequate pulmonary flow with the ductus closed, the decisions for further catheter intervention are “on-the-spot”, somewhat arbitrary judg- ment decisions in the catheterization laboratory during each individual case, but usually some type of an aug- mented systemic to pulmonary shunt, if not an atrial septostomy, is required. Perforation of the pulmonary valve in patients with pulmonary atresia and an associated ventricular septal defect Hausdorf and associates extended the use of radio- frequency perforation of the plate-like pulmonary valve to perforation of the “muscular tract” between the right vent- ricular outflow tract (RVOT) and the main pulmonary artery for the attempted palliation of ten patients with pulmonary atresia and a ventricular septal defect 10 . The distance between the RVOT and the main pulmonary artery varied between 1.2 and 12 mm. Except for two new- borns, their ten patients were much larger and older patients, some even years past the newborn period. All of the patients except the two newborns had either significant systemic to pulmonary collaterals or a surg- ically placed systemic to pulmonary artery shunt as their source of pulmonary artery blood flow. Because patients with pulmonary atresia and a vent- ricular septal defect have either a very tortuous patent duc- tus arteriosus and/or present at a later age with no ductus arteriosus, perforation of the atretic pulmonary valve without the use of a through-and-through wire usually is necessary in these patients. Before being considered for valve perforation, patients with pulmonary atresia and a ventricular septal defect should have an adequate dia- meter, main pulmonary artery documented angiographi- cally. This angiographic anatomy is obtained from biplane angiograms in the aorta adjacent to the “source” vessels for the pulmonary flow, from selective biplane injections into aortopulmonary collaterals, or even from biplane pulmonary vein wedge angiograms. The “indirect” angio- graphic pictures of the main pulmonary artery are stored as “road maps”. After the anatomy of the main pulmonary artery and its precise location are identified, an end-hole “guiding” catheter is pre-shaped to conform to the course from the right atrium to the right ventricular outflow tract (RVOT). This guiding catheter must be manipulated into the right ventricular infundibulum with the tip directed exactly in the direction of the pulmonary artery as visualized on the biplane “road maps”. It may be possible to advance the tip of the guiding catheter only to the proximal, or inflow end, of the infundibulum. The RF perforating catheter is advanced through and out of the tip of the guiding catheter. With occasional good fortune or even luck, the very thin perforating catheter passes through the in- fundibulum until it is close to, or against, the area of a tiny atretic valve structure. When this occurs, the course through the traversed infundibulum tends to align the tip of the perforating catheter more directly at the center of the stump of the atretic main pulmonary artery segment. The position is verified with biplane angiography, inject- ing through the guiding or a separate venous catheter. With the tip of the RF wire pushed against the atretic tis- sues and in the precise direction of the pulmonary artery as visualized in both PA and LAT X-ray planes, RF energy is applied for several seconds. The perforating wire is advanced in short steps toward the pulmonary artery between bursts of RF energy, and the RF energy re-applied. Very rarely, the RF perforating catheter is advanced in very short distances during the application of the energy while observing the course through the tissue very care- fully. Once through the atretic tissues and into the pul- monary artery, the perforating catheter is advanced without energy applied to it into a distal pulmonary artery branch and distally as far as is possible. The tract CHAPTER 31 Purposeful vascular perforations 853 of the RF wire from the RVOT to the pulmonary artery is examined carefully to verify that the wire is in the center of the muscular tract in both planes. The procedure then is similar to a pulmonary atresia with intact ventricular septum where the ductus arteriosus was not traversed, although maneuvering through the tract of RVOT tissue usually is even more difficult. More often, in patients with pulmonary atresia and a ventricular septal defect, the perforating catheter/wire cannot be advanced beyond the tip of the guiding catheter positioned at the proximal end of the infundibulum. If, on biplane imaging, the guiding catheter is pointing directly toward, although still some distance away from, a pul- monary artery of an adequate diameter, the RF energy is utilized to perforate through the infundibulum, to the area of the “valve”, and then through the remaining tis- sues into the pulmonary artery. This is performed with very short bursts of RF energy and small advances of the perforating catheter/wire between the applications of energy. Between each advance, the position of the perfo- rating catheter/wire and its orientation toward the valve is rechecked with small, selective, hand injected, biplane angiograms in both planes of imaging and injecting through the guiding catheter or an adjacent venous catheter in the outflow tract. The attempted perforation is continued only as long as the perforating catheter/wire stays on a direct course to the valve and the patient exhibits no hemodynamic deterioration during the proced- ure. Once the valve is crossed, the wire positioning and dilation procedure are the same as previously described for pulmonary atresia with intact ventricular septum with- out a patent ductus. After the communication has been established and the tract partially dilated, usually the tract is maintained open with an intravascular stent. Purposeful perforation of other vascular structures or total vessel obstructions Pediatric and congenital catheterization laboratory inter- ventionalists who are very comfortable with transseptal atrial puncture have extended the needle puncture tech- nique of the transseptal procedure to the perforation of multiple other structures, some for diagnostic purposes and others in order to create permanent openings. Puncture of surgically created interatrial baffles and/or patches were the logical extension of the standard atrial transseptal procedure. The venous approach usually is used, however, for baffles and some patches, the needle tip is positioned and directed very differently according to the orientation of the patch or baffle 11 . Usually, more force must be applied to the needle/transseptal set to penetrate the thicker structures of a baffle/patch. The extra force required increases the risk of the perforating needle continuing forward beyond or on the “other side” of the desired perforation into unwanted structures. The use of an RF perforating catheter through a special transseptal sheath/dilator set (Baylis Medical Co. Inc., Montreal, Canada) eliminates the extra force (and in turn, extra risk) necessary for these “transseptal” perforations. Un- fortunately, RF perforation is not applicable through patches and/or baffles that are made of synthetic (non- tissue) materials. In addition to the native atrial septum, patches in the interatrial septum and baffles within the atria, the transseptal needle and set are used to perforate and, in turn, re-cannulate totally occluded vascular channels. The transseptal needle requires a relatively straight line of access or “straight shot” from the site of catheter introduc- tion to the site being “re-cannulated” in order to transmit the forward force from outside of the body, along the needle and to the needle tip at the puncture site. When forward force is applied within any significant, “non- contained” curve in the course of the needle, the force applied to the proximal needle causes the needle to “bow” proximally and, in turn, the forward force is dissipated into the curve rather than being delivered to the tip, and the direction of the tip is changed significantly. Even with this limitation, the transseptal needle has been used successfully to puncture and rebuild long (5– 6 cm!) total obstructions in multiple different vascular chan- nels (see Chapter 24, “Venous Stents”). These include total obstructions in the native superior vena cava, the superior limbs of intracardiac venous baffles, totally disconnected right pulmonary arteries in postoperative “hemi-Fontan” patients 12 , aortic coarctations with a discrete membranous interruption, and all varieties of ilio-femoral/IVC total venous obstruction 13 . The access for these punctures is from the femoral, jugular or hepatic vein approach depending upon the vessel, the location and orientation of the obstruction and which approach provides the straight- est route to and through the obstruction. The availability of the radio-frequency perforating sys- tems has extended the possible sites of vascular obstruc- tion that might be perforated and reconstituted. With the flexibility of the RF perforating catheter (wire), and since little or no forward “force” is required for the perforation, RF perforating catheters can traverse a very tortuous route to the site to be perforated. Perforating RF catheters (wires) readily pass around relatively acute curves and, in turn, can approach the area to be punctured from sharp or acute angles. The use of the RF wire allows the perforation of the atrial septum 14 , atrial baffles and other vascular structures from a variety of venous access sites. As long as contact is maintained against the surface to be punctured by the RF perforating catheter, the RF energy will pene- trate native tissues. The usual interatrial septum is aligned parallel to, and even away from, a catheter that is introduced from the [...]... results in progressive hypoxemia and acidosis and can lead to death The likelihood of spontaneous occlusion of the ductus occurring is reduced by minimizing the manipulations through the ductus, accurately maintaining and/ or increasing the prostaglandin infusion to the patient, and maintaining the infant’s fluid volume In the event of a spontaneous closure of the ductus, the rate of the prostaglandin infusion... arterial and venous) that are encountered in pediatric and congenital heart patients and present exciting challenges for new developments in the pediatric /congenital cardiac catheterization laboratory Recannulation of total acute arterial occlusions Acute occlusion of a femoral artery during, and/ or immediately following, a retrograde arterial catheterization is not an uncommon complication of cardiac catheterization. .. catheter” connecting the jaws to an “activating handle” at the proximal end The jaws on the bioptome open to approximately 180° by moving the two sliding, side rings on the handle forward and away from the central fixed ring on the central shaft of the handle Standard bioptome catheters are available in 5- through 7-French sizes and most are at least 100 cm long There is a very tiny, 3-French bioptome... relatively short, a small indwelling arterial line often is introduced for more precise monitoring of the patient during these procedures, particularly when access for the biopsy is a problem and/ or the patient’s clinical status is precarious In most catheterization laboratories, when meticulous technique and a 2 1- or 20-gauge teflon cannula is used for the indwelling arterial line, the introduction of a small... (or re-establish if the biopsy line was removed!) a large venous access line while the pericardium is being tapped and drained with the insertion of a large size pericardial drain Circulating volume replacement is initiated with normal saline or lactate (not the flush solution containing heparin!) and plasma expanders until whole blood is available When the hemopericardium is large and/ or continues... laboratory Even if the echo machine is not used during the actual tissue sampling, an echo machine always should be available in the catheterization laboratory In the event of any instability in the patient’s condition, a pericardial effusion can be ruled out or documented definitively and immediately and, in turn, treated rapidly, depending on the echo findings Preparing the sheath and bioptome catheter for... made at torquing and advancing the cleared sheath alone, very slightly and very gingerly into the right ventricle The sheath, alone, very easily can be kinked, particularly when the tip of the sheath impinges against any structure within the heart, and/ or any forward pressure is applied concomitantly to the sheath against even minimal resistance Again, unless the sheath “falls” easily into the ventricle,... becomes one of the more challenging and time-consuming procedures in the cardiac catheterization laboratory A myocardial biopsy usually is accomplished in the cardiac catheterization laboratory and accompanied by at least a minimal hemodynamic evaluation, which includes estimates of cardiac output by Fick and/ or thermodilution determinations The hemodynamic data are usually obtained before the tissue biopsies... obtained Some institutions perform the biopsies using only echocardiographic guidance10, in which case the biopsies can be performed in a specific procedure room that does not contain X-ray equipment, in the intensive care unit and/ or even in the patient’s hospital room11 When the biopsy is performed in other than the catheterization laboratory and echo only guidance is used, the jugular approach using... flush during all of the subsequent positioning within the ventricle The pre-curved bioptome with the jaws of the bioptome closed is introduced into the pre-positioned and precurved sheath and advanced under continual fluoroscopic observation to just within the tip of the sheath The sheath is kept on a slow but continuous flush through the side port as the bioptome is introduced into and advanced within the . maintaining and/ or increasing the prostaglandin infusion to the patient, and maintaining the infant’s fluid volume. In the event of a spontaneous closure of the ductus, the rate of the prostaglandin. formation in a vein that has sluggish flow and/ or has been damaged by surgical or catheter inter- vention, including chronic indwelling intravenous catheters and infusions. Occlusions of small veins. the initial heparin therapy was not effective. When mechanical intervention in the catheterization laboratory is instituted, heparin therapy is continued. In the infant and small child, the involved