A new one-catheter torque-guide system for percutaneous exploratory abdominal angiography.

Abstract

In 1956 Ödrnan (5) introduced a technic for percutaneous selective abdominal catheterization which has since become standard in most angiography centers throughout the world. Basically, the method utilizes large 6.5 to 8.5 French preshaped radiopaque polyethylene catheters. These are inserted percutaneously into the aorta from the groin vessel by the Seldinger technic (6) and then threaded under fluoroscopy into the desired aortic branch. Although this technic is successful in the hands of an expert, it still has many shortcomings which should be emphasized. First, a separate catheter must be inserted to obtain a preliminary midstream aortogram; second, catheters with different curves may have to be exchanged for catheterizing different vessels, because of poor rotational control; and third, prolonged catheter manipulations and fluoroscopy time may be required for selective catheterization within markedly tortuous aortas or when the side vessels are acutely angled. The author has overcome these problems by using a 6F disposable polyethylene catheter with extrathin walls, rendered extremely maneuverable with a simple inexpensive torque guide. Materials The guide2 is a stainless-steel directional curve-tipped instrument 60 cm long, which is premeasured so that its terminal bead lies sheltered 2–4 mm within the catheter tip. It consists of a long stem (O. D.0.63 mm) whose terminal 7 cm is tapered and attenuated into a fine curved flexible spring (O. D. 0.38 mm). The distal half of this spring has a 3 cm diameter C-curve, but the acuteness of this curve may be modified by stretching it over a 2- or 5-ml syringe barrel. In children, small adults, or in patients in whom the subclavian approach is necessary, a more flexible guide of finer diameter (O.D. 0.56 mm) is preferred. It should be emphasized that the catheter end must also be preshaped into a small C-curve because the spring of the guide itself is too fine to impart a sharp bend to the catheter. Nevertheless, when the curved ends of the metal guide and catheter are engaged within one another, the system behaves as one, retaining the flexible curve of the catheter but gaining outstanding rotational control from the more rigid stem of the metal guide. Whereas most other maneuverable guides are complex and built to bend the catheter tip (1, 2, 4, 7), the purpose of this simple guide is to rotate a preshaped curved catheter along its long axis; a very vital function for serial selective catheterization of abdominal vessels. This instrument can therefore be called a “torque guide.” This guide remains an integral part of the catheter during hand or machine injections because it only slightly compromises the effective internal diameter of the catheter and, moreover, prevents the catheter from slipping out of the side vessel. At a pressure of 150 lb. per square inch (Cordis injector) the flow through the catheter guide system is 7 to 10 ml per second depending upon the type of contrast medium used. It is recommended that the guide be siliconized before use.