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Herein, we describe a technique that facilitates percutaneous vascular access when the traditional method of achieving access is unsuccessful.
For multiple reasons, gaining access to small vessels in pediatric patients is sometimes difficult. In instances of atrial, ventricular, or great arterial communications, a wire can be positioned from a vein or artery across the communications into an artery or vein to which access needs to be gained. This wire then serves as a target for vascular access.
All pediatric patients who underwent cardiac catheterization at Mattel Children's Hospital from July 2003 through June 2006, and at Rady Children's Hospital from July through December 2006, were considered for the wire-target technique when access could not be achieved in vessels of interest via traditional methods. Fifteen wire-target procedures were undertaken in 14 patients (ages, 4 d–11 yr). By use of a directional catheter, a Wholey or 0.014-inch coronary wire was positioned in a vessel to which access was desired. Anterior–posterior and lateral fluoroscopic views were used to target the wire and attain vascular access. The patients' diagnoses, ages, vessels to which access was gained via traditional methods and via the wire-target technique, and wire routes were retrospectively recorded, and outcomes were noted. In all instances, the technique was performed successfully and without complications.
In selected pediatric patients in whom percutaneous vascular access is difficult, the wire-target technique may be used safely and effectively to establish arterial, venous, or transhepatic access.
Sven Ivar Seldinger published his pioneering technique for achieving percutaneous vascular access in Acta Radiologica in 1953.1 This innovative method, which introduced the use of a flexible, round-ended wire to facilitate catheter insertion, was a substantial refinement to the previously accepted practice that had been described by Fariñas in 1941.2 This earlier method required the use of a large vessel to accommodate a large-bore needle through which a smaller-gauge catheter could be passed. The proliferation of the Seldinger technique has had a profound influence on contemporary medicine.3 Among its numerous advantages is that vascular access is no longer restricted to large vessels only, and the technique facilitates the catheterization of neonatal and smaller pediatric patients.4 In the modern era, the Seldinger technique, which requires the use of a stylet when the needle is introduced into a vessel, has been modified so that only an open-bore needle may be used.
Today, percutaneous vascular access in pediatric cardiac catheterization is commonplace, with well-established approaches and protocols. However, percutaneous vascular access in pediatric patients remains challenging, especially in infants and in patients who have undergone multiple procedures. Various methods aimed at facilitating vascular access have been previously described, including ultrasonographic guidance5 and Doppler-tipped needles.6 In addition, the modified Seldinger technique has been applied to less commonly targeted vessels (transhepatic, for example) and has been used to gain transthoracic access to the heart.7
Here, we describe a technique that we have used in the catheterization laboratory to attain access to vessels when a standard approach proved unsuccessful. We maneuver a wire through a previously attained vessel into the vessel of interest and perform the Seldinger technique, targeting the wire fluoroscopically. In patients who have communications at the atrial, ventricular, or great arterial level, our technique has been used to position a wire from a vein or artery across the communications into an artery or vein, or from one vein to another. This “wire-target” technique has been useful in patients who have multiple forms of complex congenital heart disease.
In the wire-target modification, initial access is attained in a central vessel via the modern-day modified Seldinger technique. After a sheath is placed, a directional catheter, such as a 4F angled Glidecath® (Terumo Medical Corporation; Somerset, NJ), is then used to position a 0.035-inch Wholey Hi-Torque Floppy™ guidewire (Mallinckrodt Inc., part of Covidien; Hazelwood, Mo) or a 0.014-inch HI-TORQUE Balance Middleweight UNIVERSAL guidewire (Abbott Vascular, part of Abbott Laboratories; Santa Clara, Calif) in the targeted vessel. This may be performed within the same circulation, such as venovenous access, or across circulations for venoarterial or arteriovenous access. When there is a need to cross circulations, defects in the atrial or ventricular septa or great arterial connections (centralshunts) can be used.
After the wire is appropriately positioned in the vessel of interest, anterior–posterior and lateral fluoroscopicviews are used to align the percutaneous needle with the target wire. The needle is carefully advanced toward the target wire until its tip is observed in both projections to have engaged the target wire. A blood flash is usually seen. Finally, a wire is inserted into the needle, and it “tracks” the target wire. Vascular access is then attained via the standard Seldinger technique.
By means of a retrospective database review, we identified all pediatric patients who had undergone cardiac catheterization at 2 hospitals: Mattel Children's Hospital in Los Angeles, from July 2003 through June 2006; and Rady Children's Hospital, San Diego, from July through December 2006. All procedures in which the wire-target technique was used or attempted were identified and reviewed. Angiograms, catheterization reports, and medical records were analyzed. We recorded the patients' data, including diagnoses, ages, body weights, vessels to which access was gained via the traditional method, vessels attempted via the wire-target technique, and the routes of the wires (Table I). The outcomes of the procedures were noted.
All pediatric catheterization patients had been considered for the wire-target technique when access could not be attained in the vessel of interest by use of the modified Seldinger technique, yet access was nonetheless achieved in another vessel. In each patient, additional access was necessary in order to facilitate catheterization, because diagnostic data or an intervention had been deemed necessary at the time of the procedure. When vessels of interest were found to be occluded, or when it was not possible anatomically to position a wire in such vessels, the wire-target technique was not attempted.
Use of the wire-target technique proved feasible in a total of 15 procedures that were performed in 14 patients. Their ages ranged from 4 days to 11 years (median age, 5 mo). Ten of the 15 patients were younger than 1 year of age, and 13 of the 15 were 24 months of age or younger. The smallest patient weighed 3.5 kg. Diagnoses varied, and included single-ventricle physiology in 6 of 15 patients, and biventricular physiology with atrial, ventricular, or great arterial communications. Eleven patients had undergone cardiac surgery. The wire-target technique was used for venovenous access in 1 patient who had cardiomyopathy. Figures 1, ,2,2, ,3,3, ,44 and and55 reveal procedures that were performed in 5 patients of different ages who had various congenital cardiac abnormalities, surgical histories, and target-wire treatments.
In all of the eligible patients, the wire-target technique was performed successfully and without complications. In some instances, when the atrial or ventricular septum was crossed, transient electrocardiographic changes, bundle branch block, or complete heart block occurred. These changes all resolved when the catheter and wire were removed from the heart. Within the study group, procedural fluoroscopy lasted a mean time of 58.3 minutes and a median time of 47.4 minutes.
In pediatric cardiology, patients are often very small, and they may have previously undergone multiple placements of indwelling catheters. These factors can pose substantial challenges to percutaneous vascular access. Our standard approach to vascular access includes the use of ultrasonography, which enables access to the internal jugular vein, and audible Doppler, which enables access to a femoral vessel. In our patients, we had attempted these techniques without success before we undertook the wire-target technique.
The wire-target technique affords the operator a reasonably simple method by which to safely and effectively facilitate vascular access, in the process perhaps sparing the patient multiple needle punctures or a surgical cutdown. The technique is effective from an arterial, venous, or transhepatic approach. Standard techniques are required in order to position a wire in the targeted vessel and to enable more precise vascular access by use of the modified Seldinger technique. When we performed this procedure in our laboratories, we were successful in achieving access in all patients in whom standard methods had initially posed a challenge.
The wire-target technique is safe, especially when one is cognizant of some specific hazards. When attempting to attain access by crossing circulations via an intracardiac or great arterial communication, one must be aware of possible consequences. During the crossing of an atrial-level shunt, for instance, a degree of hemodynamic instability may occur due to catheter-induced regurgitation of both the aortic and mitral valves. This is generally well avoided or mitigated by using a soft catheter, such as the 4F Glidecath. When access across a ventricular septal defect (VSD) is required, a risk of heart block arises, especially in patients who have l-looped ventricles. The risk of a generally mild, transient, and well-tolerated degree of heart block is always present to a certain extent when intracardiac and especially intraventricular catheterization is performed. However, the risk of more significant heart block increases when catheters or wires are placed across a VSD. During this study, we crossed the VSDs of 3 patients, 2 of whom had single-ventricle hearts (unbalanced atrioventricular canal, pulmonary atresia, and VSD), and 1 of whom had tetralogy of Fallot. Whereas the overriding aorta in tetralogy of Fallot did not pose a substantial problem to us, we took great care when we crossed the VSDs in the other 2 patients. Neither experienced persistent or problematic heart block. Various degrees of heart block that we encountered in other patients were transient. Finally, although crossing circulations between the great arteries with a catheter through a surgically created shunt is generally well tolerated, risks include shunt occlusion with ensuing cyanosis or decreased cardiac output, embolization of clot or granulation tissue within the shunt, or disruption of shunt integrity. Using a soft catheter minimizes these risks.
Our technique can obviate the need for other methods or devices, in that its only requirements are a directional catheter and wire (tools that are standard in a catheterization procedure) and customary catheterization techniques (in order to manipulate the wire into place). Accordingly, the operator needs no new skill sets.
Another benefit of the procedure is that central venous or arterial lines can be left in place long-term for medical access or monitoring. This can be done when vascular access is very challenging or when simpler access (such as a femoral line) is not desirable. One 2-month-old patient in our study required a central venous line as part of intensive care. We used our technique to facilitate the placement of a right internal jugular venous line after catheterization had been completed via a transhepatic approach.
Drawbacks of the wire-target procedure include the need for at least 1 vascular site to have been previously attained. Second, the risk of radiation exposure is increased. However, in our patients, we believe that increases in fluoroscopy times were minimal. The total times (mean, 58.3 min; median, 47.5 min) among our patients were similar to those in other complex cases in our laboratories. For example, during 2007, 10 patients who had single-ventricle physiology after bidirectional Glenn anastomosis and who underwent diagnostic and interventional catheterization in our laboratories had fluoroscopy times similar to those of the patients on whom we report here (mean, 51.7 min; median, 52.2 min). Finally, the wire-target technique is useful in the venous or arterial circulation only, depending on the initial access site, and an existing communication between the 2 circulations is required in order to cross from 1 side to the other. Although it is conceivable that atrial septal perforation via the Brockenbrough technique8 could be used, we have not performed a transseptal procedure with this technique.
Precise vascular access via the wire-target technique has become a valuable ancillary method in our pediatric cardiac catheterization laboratories when venous or arterial access is unsuccessful by use of the modified Seldinger technique.
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