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Implantable vascular access devices – past, present, and future

D aily therapeutic phlebotomy followed by the return of sedimented autologous red blood cells to patients with hyperviscosity syndromes marked the early beginnings of manual therapeutic apheresis in the 1950s. In the following decades, advances in apheresis practice and instrumentation, inspired by the Cohn Fractionator, continued with the advent of continuous-flow blood cell separation technologies, including the NCI-IBM 2990, the Aminco Celltrifuge, and the COBE Spectra. These advances in apheresis were critically dependent on establishing vascular access capable of withstanding negative pressures in the draw line (generated by inlet flow rates up to 150 mL/ minute), and of tolerating positive pressures in the return line. In situations where superficial peripheral veins are inadequate, the ability to repeatedly and reliably access the vascular system for apheresis has been made possible largely due to advances in the fields of nephrology, oncology, and nutrition to deliver chronic hemodialysis, administer chemotherapy, and provide long-term parenteral nutrition, respectively, and to support frequent laboratory testing (see Table 1). With many similar requirements, such as high flow rates and hemocompatibility, the evolution of venous access in hemodialysis has had an important impact on vascular access practices related to apheresis. Before the widespread availability of implantable vascular devices (IVADs), vascular access for hemodialysis was gained by repeated cannulation of peripheral blood vessels. This practice damaged native arteries and veins, and quickly rendered these vessels useless over a brief period of time. According to Dr. Cimino, “vascular access was the Achilles heel of chronic hemodialysis.” In 1959 the Scribner-Quinton Shunt was invented. This external U-shaped Teflon tube was used to connect an artery and a vein, and could be left in place between treatments. But theses shunts usually only lasted a few months and had many complications, including thrombosis, local and systemic infections, necrosis at the Teflon tubing exit sites, dislodgement of the shunt resulting in severe blood loss, and severe patient anxiety. Around the same time in 1966, the Brescia-Cimino fistula was introduced, and these surgically created arteriovenous fistulae allowed for very high flow rates. However, only those with adequate peripheral vasculature were suitable candidates, and the time required for arteriovenous fistula maturation (typically a few months) was a major disadvantage. Some of these major limitations for arteriovenous fistulae were soon overcome by the introduction of expanded polytetrafluorethene grafts. In 1967, non-tunneled catheters were percutaneously placed via the external jugular or subclavian veins into the superior vena cava for prolonged parenteral nutrition in surgical patients with complex gastrointestinal disease. Six years later, these indwelling silicone rubber catheters with a Dacron cuff – for fixation by ingrowth of tissue – were placed into the superior vena cava and subcutaneously tunneled to exit on the chest. Dr. Hickman modified the Broviac catheter design by increasing the wall thickness and lumen diameter for the administration of chemotherapy in marrow transplant recipients. The next major milestone in the evolution of IVADs was marked by the introduction of totally implantable port-catheters (hereinafter referred to as “ports”) to replace central venous catheter use in oncological treatments, including administering chemotherapy, blood products, and antimicrobial agents. Ports for blood sampling and chemotherapy administration were only required to be locked with heparinized saline after each entry.