Dynaflo Case Studies


Addressing the Unique Hemodynamics in Above-knee Bypass Grafting Clinical Experience Paul Kreienberg, MD Associate Professor of Surgery, Albany Medical Center; Albany, New York September 2005 Expanded polytetrafluoroethylene (ePTFE) grafts are widely recognized as a viable alternative to autologous veins when such natural conduits are not available. Advanced technology applied to ePTFE grafts has made them even more attractive for surgeon consideration–providing significant benefits both intraoperatively and in helping to improve clinical outcomes. Such technology is represented in Dynaflo™ Bypass Grafts with preformed cuffs, taking into account the hemodynamics at the distal anastomosis above the knee. Hemodynamics in cuff technology are about controlling the forces or the mechanics of blood circulation in a particular part of the vascular system where a cuffed graft is applied. Such control is brought about through the design of a cuff, making the graft better suited for optimizing and managing blood flow.¹	Figure 1 Preoperative arteriography demonstrates complete occlusion of the superficial femoral artery.
Cuffed bypass grafts, then, for above the knee are specially designed and engineered to optimize blood flow or the hemodynamic efficiency of an ePTFE bypass graft at the distal anastomosis. Optimizing blood flow at the site of the anastomosis is a major advantage in helping to reduce the incidence of intimal hyperplasia formation for improved patency rates.^2,3
Figure 2 Postoperative angiogram shows excellent antegrade flow with three vessel run-off. Also, note there is minimal retrograde flow due to the extensive SFA occlusion.	Cuff grafts are formed from one continuous length of ePTFE tubing. As such, they provide a smooth transition between the body of the graft and the cuff. Grafts manufactured with cuffs offer unique design characteristics and consistent geometries (shapes and sizes) to ensure optimal blood flow. Autologous vein cuffs constructed intraoperatively cannot provide consistent shape or a smooth transition as with pre-cuffed grafts. And because vein cuffs require vein harvesting as additional surgery, operating time is naturally increased in my experience. The evolution of cuff technology to its present-day form is based on the realization that cuffs must be designed specifically for where they are used in different parts of the body.^2,3 Such accurate match of hemodynamics and anatomy with cuff design optimizes blood flow which may better help reduce the risk of intimal hyperplasia formation.⁴ The Dynaflo™ Bypass Graft is the only graft specially created to address the unique hemodynamics at the distal anastomosis of above-knee femoropopliteal, axillary-femoral, femoral-femoral, and axillary-bifemoral bypass grafts.
When implanting Dynaflo™ Bypass Grafts, it is recommended that the distal anastomosis be constructed after tunneling. The graft should be drawn through the tunnel or sheath from the distal incision to the proximal incision by the non-cuffed end only. Also, Dynaflo™ grafts are best routed via a deep tunnel that approximates to the anatomical route of the natural artery.
The following case is representative of my clinical experience with Dynaflo™ Bypass Grafts. A 64-year-old male Caucasian was seen suffering from bilateral claudication. Patient profile includes history of smoking, also medical history of atherosclerotic heart disease, peripheral vascular disease, hypertension, hyperlipidemia, and intermittent claudication. (Patient’s father died from complications of myocardial infarction and stroke.) Status-post PTCA with stent placement to LAD was done in August 2001. Arteriography demonstrated complete occlusion of the superficial femoral artery in both legs (figure 1). Prior to the arteriogram, he had pulse volume recordings which were consistent with superficial femoral artery disease. There was no palpable pulse.
Two months prior to bypass grafting, ankle-brachial indices (ABIs) were 0.83 and 0.86 for left and right ankle, respectively, which were suggestive of bilateral lower extremity arterial insufficiency. Further evaluation was done with peripheral angiogram. There were two, separate, hospital admissions in which above-knee common femoral to popliteal bypass was performed, each with a 7 mm Dynaflo™ Bypass Graft. The first bypass procedure was performed on the right leg in late February 2005. The second procedure, on the left leg, was performed in early March 2005. The graft handles well during implantation, making it relatively easy to implant. The cuff is easy to suture and although it might seem bigger than what you are use to putting in, you actually don't need as much artery as you might think.	Figure 3 Follow-up Duplex scan at 3 months. This demonstrates the creation of the vortex within the cuffed portion of the Dynaflo™ graft, minimal retrograde flow and ample antegrade flow. Dissipation of the vortex with systole was also seen.
The surgical goal was to restore normal blood flow and relieve claudication. Hospital stay was three days for each procedure. The patient was seen again towards the end of March 2005, after the last operation, and revealed no postoperative complications (figure 2).The wounds healed nicely and his walking improved with no pain. Standard postoperative follow-up included ultrasound and ABIs, all of which were normal (figure 3). He had palpable pulses upon physical exam. There were normal velocities and the anastomoses appeared good from the ultrasound exam. The patient is happy with the outcome and was able to resume his occupation as a bus driver two weeks following the second bypass procedure. Conclusion The principles of cuff technology address hemodynamic forces that can be modified for the purpose of optimizing blood flow in helping to reduce the risk of intimal hyperplasia formation to improve patency rates. And the geometry of the cuff is critical to its application in the area of the vascular system where a cuffed graft is implanted. Because flow dynamics are different in specific areas of the body, as in above the knee versus below the knee, a different cuff geometry is required for managing the higher flow rates above the knee. While the Distaflo® Bypass Graft is suited for below the knee procedures, the Dynaflo™ Bypass Graft is suitable for above the knee bypass. From my clinical experience, having the right cuff geometry for the right application (above the knee and below the knee) helps to improve the potential of achieving optimal clinical outcomes through enhanced hemodynamics.
References: 1. Steinthorsson G, Sumpio B. Clinical and biological relevance of vein cuff anastomosis. Acta chir belg. 1999;99:282-288. 2. Stonebridge PA, Prescott RJ, Ruckley CV. Randomized trial comparing infrainguinal polytetrafluoroethylene bypass grafting with and without vein interposition cuff at the distal anastomosis. J Vasc Surg. 1997;26(No. 4):543-550. 3. Panneton JM, Hollier LH, Hofer JM. Multicenter randomized prospective trial comparing a pre-cuffed polytetrafluoroethylene graft to a vein cuffed polytetrafluoroethylene graft for infragenicular arterial bypass. Ann Vasc Surg. 2004;18:199-206. 4. Fisher RK, How TV, Toonder IM, et al. Harnessing haemodynamic forces for the suppression of anastomotic intimal hyperplasia: the rationale for precuffed grafts. Eur J Vasc Endovasc Surg. 2001;21:520-528.

Please consult product labels and package inserts for indications, contraindications, hazards, warnings, cautions, and information for use. The physician has been compensated by Bard Peripheral Vascular, Inc. for his time and effort in preparing the above case study for Bard’s further use and distribution. Bard, Dynaflo and Distaflo are registered trademarks of C. R. Bard, Inc., or an affiliate. Copyright © 2005, C. R. Bard, Inc. All rights reserved.