John D. Corson

Instrumental evolution of the valve incision method of in situ saphenous vein bypass

The previously stated advantages of the valve incision method of in situ saphenous vein arterial bypass have now been confirmed by others. However, this method has been limited by its time-consuming technical demands. Considerable experience with this bypass in conjunction with retrograde serial valve disruption with instruments of similar design principle (by Hall and Cartier) has been accumulated in Europe. However, the combination of the trauma of blunt valvular fracture and the sensitivity of endothelium to frictional shear has precluded use of these instruments in veins less than 4 mm in size, and the results have not been significantly better than those obtained with reversed vein bypass. An instrument (valve cutter) that achieves serial valve incision safely and consistently without mandatory exposure of each valve site has now been developed. Of the last 166 consecutive bypasses, the saphenous vein was suitable for use of this instrument in 116 instances (70%). The patency of these bypasses as determined by life-table analysis has shown no significant difference when compared with bypasses performed under similar conditions in which the cutter was not used. On the basis of this investigative and clinical experience, the majority of in situ saphenous vein arterial bypasses can be safely facilitated and simplified by use of this instrument.

The anatomy of the greater saphenous venous system

To define surgical anatomy, a prospective study of the greater saphenous venous system in 385 instances in 331 patients was carried out with the use of prebypass phlebography (either pre- or intraoperative). The phlebographic interpretations were confirmed during the operative procedures and from the completion angiogram. These details were recorded and analyzed by a specific computer program. These data consisted of a number of superficial branches, perforators, the identification of valve leaflets, sinuses, and the size and position of the main venous trunk both in the thigh and in the calf. The study showed that a single trunk was present in the thigh in 65% of patients and in the calf in 45%. The remainder were variants of double systems. In two thirds of patients who had complete double systems, the larger system was used for in situ bypass but the rest required the use of parts of both systems. Phlebography was accurate in the depiction of the anatomic variations (93%), double systems, cross connections, and perforator branches (87%). However, the number of competent valves could not be accurately determined (accuracy, 68%). The diameter of the vein was frequently underestimated (in 80% by 1.1 +/- 0.4 mm) and hence could not be used as an index of vein adequacy. After phlebography, four patients had transient rises in serum creatinine levels and one had an iatrogenic thrombosis of a distal segment. This study suggests that the precise anatomy of the greater saphenous venous system should be determined preoperatively by phlebography since this information is valuable for proper surgical planning before vein is used as a graft or for in situ bypass in the lower extremity.

Peroneal artery bypass: A reappraisal of its value in limb salvage

In general the surgical literature has expressed pessimism about the value of bypass to the peroneal artery for limb salvage. The combination of greater technical difficulty, low patency rates, and hemodynamic failures have led to the establishment of this prejudice. In a review of 284 arteriograms in limbs with infrapopliteal arterial occlusion, the peroneal artery was the least diseased in 40% and was the only available vessel in 37% of instances. One hundred fifty-two peroneal bypasses have been performed in a 7-year period, 116 by the in situ method, 23 with excised vein, and 13 by nonautogenous conduits. During the same period 125 anterior tibial and 114 posterior tibial bypasses were also done. The mean preoperative ankle/brachial indices were 0.27 for peroneal, 0.25 for anterior tibial, and 0.29 for posterior tibial bypasses. These were converted to mean postoperative indices of 0.84, 0.86, and 0.92, respectively. Corresponding transmetatarsal/brachial indices were 0.72, 0.75, and 0.90. Rest pain was relieved in all these patients, and in 94 patients with tissue loss, there were 11 major amputations, nine healed forefoot amputations, and 20 healed digital ray amputations. Hemodynamic failures were two in the peroneal, two in the anterior tibial, and three in the posterior tibial group with one perioperative amputation in each. The cumulative limb salvage rate at 3 years for the peroneal group was 81%. This experience has shown that the patency and limb salvage rates obtained are comparable to those for the anterior and posterior tibial arteries and that hemodynamic failure is an uncommon occurrence.(ABSTRACT TRUNCATED AT 250 WORDS)

Transcutaneous flow measurements in in-situ bypasses: an assessment of duplex scanning

Measurement of laminar flow using an ultrasound scanner was shown to have a high degree of correlation with quantified timed flows (r = 0.98, p ≤ .001). Sixty-one in-situ bypasses had flow assessed both proximally and dis tally. Mean fistula flow (proximal-distal flows) for time periods 1-8 weeks, 3 to 8, and 9+ months were 108, 85, and 16mls respectively. Distal bypass flow remained constant despite a significant decrease in fistula flow between the later time periods (p ≤ .001) (unpaired t-test). There was no evidence from the study that proximal flow through fistulas of varying resistances adversely affected the distal bypass flow.

Effects of isovolemic hemodilution on abdominal aortic aneurysmectomy in high risk patients

Intraoperative isovolemic hemodilution might increase blood flow and tissue oxygenation in the periphery but there is concern that acute anemia may have deleterious effects on myocardium in patients with coronary artery disease. This study investigates the effects of intraoperative isovolemic hemodilution on morbidity, mortality and hemodynamics in 32 patients with significant cardiovascular disease undergoing elective abdominal aortic aneurysmectomy. The average hematocrit was lowered intraoperatively from 43% to 31% by withdrawing blood and replacing volumes with 1:3 Ringers lactate. In ten patients myocardial function was evaluated during aortic cross-clamping and declamping in the face of hemodilution. There were two deaths: one myocardial infarction and one multiple organ failure. Aortic cross clamping did not change heart rate, vascular pressures (VP), vascular resistance (SVR), cardiac output (CO), and left ventricular stroke work (LVSW). Following declamping, VP, CO and LVSW decreased and SVR increased momentarily (p less than 0.05), but the myocardial function did not change. Isovolemic hemodilution had no apparent adverse effects on morbidity, mortality and cardiovascular performance in these patients.

Hemodynamic Observations Related to in-Situ By-Pass Arteriovenous Fistulae

A total of 145 in-situ saphenous vein bypasses were studied postoperatively by Echo Doppler (Duplex) ultrasound scanning. Volumetric blood flow was measured transcutaneously in each case. Five patients did not clinically improve despite patency of their bypasses. Three other patients had persistent edema and arteriovenous fistulae. Surgical ligation of dominant fistulae in these 8 pa tients resulted in significant improvement of distal bypass flow in 7 patients (p < 0.01, Students paired t-test) with a concomitant decrease in fistula flow and resolution of symptoms in all patients. An occasional patient undergoing in-situ bypass may have a hemodynamic compromise postoperatively that is correctable by fistula ligation.

The in situ saphenous vein arterial bypass by valve incision

Publisher Summary This chapter discusses the in situ saphenous vein arterial bypass by valve incision. The provision of a normal functioning endothelium that will retain a nonthrombogenic surface even in low flow situations is the theoretical ideal in vascular surgical conduits. Smooth tapering and matching of the sizes of the conduit at both the ends of the arterial bypass has definite and obvious hemodynamic flow advantages. After the most proximal valves have been incised, the venous anatomy determines the subsequent techniques for valve incision. It is found that when the saphenous vein is greater than 4 mm with a single trunk in its thigh portion, a detachable intraluminal valve cutter is used that divides the cusps up to the level of the knee without the necessity of surgical exposure of the vein. A small incision is made posterior to the previously marked vein below the level of the knee joint. The vein is examined for suitability at this point because it is, in general, at its narrowest there. Once arterial pressure has been established at the knee level, the valvulotome is used for all subsequent valve incisions.

Distal in situ vein bypass torsion—A technique to avoid it

One of the stated advantages of the in situ bypass is that twists or torsion along the vein are automatically prevented by the technique. Unfortunately, this is not strictly true because the distal mobilized end of the vein, which is being anastomosed to the outflow tract, is quite prone to twists of 180 to 360 degrees after its arterialization. This torsion may result in either immediate cessation of flow or later formation of an anastomotic stenosis. We describe a technique that, when used, should eliminate all such problems.

Management of pediatric visceral arterial and aortic coarctation.

Two unusual pediatric vascular problems have been managed surgically. The first patient is a five-and-a half-year old girl who presented with renal artery stenosis and aneurysm and renovascular hypertension. This was treated by excision of the aneurysm and reimplantation of the right renal artery. The second patient is a two-year old girl with atresia of the abdominal aorta, superior mesenteric artery (SMA) and both renal arteries. She was treated by PTFE patch graft angioplasty of the aorta, SMA reimplantation and bilateral aorto-renal autogenous saphenous vein bypass.

Limitations of the Use of Intra-Arterial Fibrinolytic Agents in Acute Lower Limb Ischemia

The use of direct regional intraarterial low dose fibrinolytic therapy was retrospectively studied in a group of 25 patients with acute lower limb ischemia. Bleeding problems were minimized due to careful monitoring of fibrinogen lev els. However two bleeding complications developed during lytic therapy on pa tients who had undergone recent surgical intervention. Following lysis a surgically correctable lesion was seen in one recently occluded conduit and in four late bypass occlusions. Eighty-three percent of the patients who had some lytic response required surgical intervention. The average time of fibrinolytic infusion was 46.7 hours.