During medical procedures, fluids of different types need to be injected into human tissue and vascular structures. One such procedure is known as angiography. Angiography is a procedure used in the detection and treatment of abnormalities or restrictions in blood vessels, heart chambers and heart valves. During angiography, a radiographic image of a vascular structure is obtained by injecting radiographic contrast material through a catheter into such a vessel, heart chamber, or heart valve. X-rays are then passed through the region of the body in which the contrast material was injected. The X-rays are absorbed by the contrast material causing a radiographic outline or image of the blood vessel containing the contrast material. The x-ray images of the blood vessels filled with the contrast material are usually recorded on the film or videotape and displayed on a fluoroscope monitor.
The injection of the contrast or other fluids can be performed either manually or automatically. In both procedures, a catheter is inserted into a vessel, which in turn is connected to a fluid line leading to a manifold and in turn to an injector or syringe. The plunger of the syringe is then either manually or automatically depressed to inject fluid through the fluid line, the catheter, and into the patient.
In certain situations, it is necessary to dilute the concentration of contrast being injected into a patient. For example, in those patients with renal insufficiency incapable of processing concentrated contrast through their system, or in cases where a large amount of contrast is used, such as complicated coronary interventions (PTCA) or peripheral (PTA) cases with runoffs, direct injections of contrasts, are not possible. Accordingly, it is necessary to mix the contrasts and saline prior to injection to arrive at the appropriate dilution percentage. Such processes are necessarily slow and are currently difficult to achieve.
In addition, during injections, it is desirable for the physician or technician to be provided with feedback as to the pressure within the vessel. This is commonly provided by way of a pressure transducer mounted relatively close to the injection apparatus. However, since a relatively long expanse of conduit exists between the catheter and the injector, typically on the order of four feet or more, pressure waveforms must be transmitted through the fluid contained within that conduit all the way from the body of the patient, through the catheter, and back to the pressure transducer. Due to such distances, the waveforms may be substantially dampened by the time they reach the transducer thereby providing an inaccurate or poor signal for display to the physician.
Furthermore, after an injection is made, and it is desired to remove the contrast from the injection system or change the fluid being injected, it is currently necessary to evacuate or aspirate the entire injection line. It would be advantageous if the waste could be quickly removed, while at the same time limiting the total volume of waste fluid encountered by the system.