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.