Declotting grafts with thrombolysis

Abstract

Percutaneous declotting of dialysis grafts has been evolving since its introduction in the early 1980s. At first, a low-dose thrombolytic infusion through a single catheter was used. Crossing catheters with a higher dose infusion was then introduced. The next method used was a pharmacomechanical thrombolysis, which uses crossing catheters and pulse-spray technique. Mechanical displacement of the platelet plug at the arterial anastomosis is necessary. Residual clot in the midgraft is mobilized with Fogarty balloons and/or angioplasty balloons. The underlying cause of graft failure, which is typically a stenosis at the venous anastomosis, must be addressed. The viability of a graft after successful lysis is probably most dependent on successful treatment of the lesion that caused the graft to thrombose. If an angioplasty of this lesion is not successful, one can consider directional atherectomy or stents. Alternatively, a surgical repair with a patch angioplasty or with an interposition graft can be performed. Recently, alternative declotting devices have been introduced. The Amplatz device and the Possis device are 2 such devices. Additionally, aspiration thrombectomy is being used with or without addition of lytic agents to attempt to declot grafts. These newer devices and techniques must be shown to be similar in terms of efficacy and cost when compared to pharmacomechanical thrombolysis before being considered for widespread use. Ultimately, it is the management of the platelet plug at the arterial anastomosis and the venous stenosis that will determine how long the graft will function after the procedure. The lyse and wait (L&W) technique was described in 1997 as a quick and simple method to declot arteriovenous (AV) grafts. A 250,000 U urokinase (5 mL), 5,000 U heparin (1 mL) mixture (total 6 mL) is injected into the graft via a 22-gauge angiocatheter. This mixture is allowed to sit in the graft for 30 to 60 minutes. The same technique can be used with any lytic agent. A multicenter randomized prospective study comparing pulse-spray pharmacomechanical thrombolysis versus L&W was recently completed. Eighty-eight patients were randomized. L&W on the average was 20 minutes quicker than pulse-spray with similar technical success and patencies. With similar results and faster procedure times, we believe L&W to be a good alternative for dialysis qraft declotting.