Effect of outflow level and maximum graft diameter on the velocity parameters of reversed vein bypass grafts.

OBJECTIVE: The objective of this study was to define a normal range of distal graft velocity (DGV) and peak systolic velocity (PSV) on the basis of outflow level and maximum graft diameter for infrainguinal reversed vein bypass grafting (RVG). METHODS: This study was designed as a prospective study of consecutive patients who underwent infrainguinal RVG from 1994 to 1997 in a university hospital and university-affiliated teaching hospital. All patients who underwent infrainguinal bypass grafting from 1994 to 1997 were placed in a prospective protocol with duplex scanning to better define the hemodynamics of normally functioning RVG. Graft revisions were performed for patients with velocity ratios of more than 2.5. One hundred twenty-one patients were entered into this protocol, and 114 were followed more than 3 months after RVG. Seven patients were excluded: five for death within 3 months, one for graft infection, and one for graft occlusion before the baseline duplex scanning. DGV and PSV were determined for each type of outflow (popliteal, crural, and pedal) and for ranges of maximum graft diameter. These then were correlated with subsequent graft occlusion or graft revision (graft failure). RESULTS: Grafts with larger diameters were associated with lower DGVs (P <.001), and more proximal outflow arteries were associated with higher DGVs (popliteal, 75 cm/s; crural, 50 cm/s; and pedal, 40 cm/s; P <.01).The mean PSVs were 150, 140, and 122 cm/s for popliteal, crural, and pedal grafts, respectively, but the difference was not statistically significant. The assisted primary patency rates for the grafts in this series were 99%, 92%, and 92% at 1, 2, and 3 years. CONCLUSION: Graft diameter and location of the distal anastomosis significantly affect the flow velocity in RVG. Other variables did not influence these parameters. Currently established criteria for arteriography or graft repair on the basis of graft velocity parameters may be improved if they can be modified depending on diameter and outflow.     

Long-term results with aorta-to-coronary artery bypass vein grafts

From our experience with more than 500 patients treated with aorta-to-coronary artery bypass vein grafts, follow-up of the first 350 patients for a period of from 6 to 43 months is analyzed. The group had 82% good results, 4% failures, 10% operative deaths, 3% late deaths, and 1% late deaths not related to the graft. Preoperative and operative factors are correlated with early and late results. The number of late deaths has not increased with the passage of time, although a distinct, moderate degradation in the quality of results in the living patients is seen. The presence of prior infarction, significant functional myocardial impairment, or extensive involvement of the coronary arterial tree tends to diminish the quality of results in survivors and to be associated with both degradation of the quality of results with the passage of time and the occurrence of late deaths.     

Effect of twist on flow and patency of vein grafts

This article examines the effect of twist on flow through reversed vein segments in vitro and its effect on graft patency in vivo. Excised canine superficial femoral veins were perfused in vitro with normal saline solution or canine blood. Perfusion was carried out at five pressures and against three outflow resistances. Increasing increments of twist were applied to the outflow end of the vein. Flow was measured at each level of twist. With both saline solution and blood, flow was unaltered until twist reached 140 to 180 degrees. Flow then decreased sharply, stopping completely at 175 to 200 degrees of twist. In vivo experiments were then performed in 13 dogs. Reversed superficial femoral veins were used as end-to-end grafts to bypass the iliac arteries. Each graft was deliberately twisted 0, 45, 90, 135, or 200 degrees. All grafts were harvested 6 months after surgery. Eighteen of 20 grafts twisted 135 degrees or less remained patent. However, all five grafts twisted 200 degrees were thrombosed within 4 hours of surgery (p less than 0.05). These data suggest that in patients a slight amount of graft twist probably does not reduce flow; however, more than 135 degrees of twist will greatly reduce flow, leading to early graft thrombosis.     

Effect of thromboxane synthetase inhibition on canine autogenous vein grafts

This study examined the effect of an orally active thromboxane (TXA2) synthetase inhibitor (TSI) on the patency, TXA2 production, and platelet accumulation of reversed autogenous vein grafts. Ten dogs received TSI (U-63557A) 10 mg/kg po q8 hr for 6 weeks, beginning 24 hr prior to surgery, while 15 control dogs were untreated. One jugular vein was harvested and stored in 37 degrees C saline for 1 hr to induce mild endothelial injury (stored). Normal and stored jugular vein grafts (8 cm) were then implanted in opposite femoral arteries while 3-cm segments of the same veins were implanted in the carotid arteries. Femoral graft flow was restricted with a 5 Fr distal arterial stenosis and patency determined by arteriography at 1, 2, 4, and 6 weeks. Vein graft endothelial surface TXB2 production was measured by RIA at graft implantation and in carotid grafts harvested at 1 week. 111In-labeled platelets were given iv 24 hr prior to carotid graft harvest to determine graft-platelet deposition. TSI treatment improved early (1 week) femoral vein graft patency from 63 to 89% (P less than 0.05), a trend that persisted for 6 weeks. Warm saline storage reduced 1-week graft patency from 83 to 63% (P less than 0.05), a difference that decreased with time. TSI treatment resulted in a marked decrease in TXB2 production, but was not associated with decreased 111In-labeled platelet deposition in carotid vein grafts. Warm saline storage increased graft-platelet deposition which was predominant at the arterial anastomoses. TSI treatment may improve early vein graft patency during the transient period of endothelial injury.     

Clinical results of common strategies used to revise infrainguinal vein grafts

Purpose: Patients who have failing infrainguinal bypass grafts or failed grafts reopened with lytic therapy represent a group at high risk of subsequent failure. Previous studies suggest that vein patch angioplasty and jump grafting may be less durable than interposition grafting as a method of correcting graft lesions. Our objective was to assess the value of various technical strategies for graft revision in a series of autogenous infrainguinal bypass grafts and to assess how these variables might affect cumulative graft patency (CGP) rates.Methods: We retrospectively reviewed the clinical course, anatomic sites of revision, and type of revision performed on 67 grafts in 58 patients who underwent at least one revision from 1991 to 1995. Results were assessed with regression analysis and Kaplan-Meier estimates of CGP rates ( p < 0.05 was considered significant).Results: Sixty-seven vein grafts underwent revision of 112 anatomical sites in 95 operations. Forty-nine of 67 grafts were single-segment greater saphenous vein grafts and 18 were composite (>1 segment) grafts, with an overall 5-year CGP rate of 72%. No difference was observed between the 4-year CGP rate in grafts with hemodynamically significant distal anastomotic stenoses repaired primarily with jump grafts (n = 20, 71% CGP rate) and those with stenoses found only in the graft body (n = 41, 89% CGP rate). Vein patch angioplasty was used primarily, but not exclusively, for focal graft body stenoses (n = 35), whereas interposition grafts (n = 11) were reserved for more diffuse strictures; no significant difference in 3-year CGP rates was observed (94% and 73%, respectively).Conclusion: Using an appropriate revision strategy that favors vein patch angioplasty for graft body lesions and jump grafts for distal anastomotic lesions, acceptable assisted patency rates can be achieved in grafts that are at risk for repeated failure. (J Vasc Surg 1996;24;909-19.)     

Right ventricular metastatic choriocarcinoma obstructing inflow and outflow tract

We operated on a 34-year-old man with a metastatic tumor that extended from the tricuspid valve to the pulmonary valve and obstructed the right ventricle inflow and outflow tracts. The tumor was removed with preservation of the tricuspid valve. Additional chemotherapy was carried out according to the BEPO (etoposid, eisplatin, bleomycin, vincritin) scheme. Histology revealed metastasis of a choriocarcinoma originating from the right testis. Computed tomography performed after 6 months detected no metastases in the lungs. Magnetic resonance imaging showed a thickened right ventricle free wall and apex. The patient is doing well 18 months postoperatively.     

Transaortic inflow and outflow cannula for centrifugal mechanical assistance

A specific cannula allowing single site transaortic inflow and outflow cannulation for centrifugal assist devices is described. The cannula is inserted through a straight 18 mm collagen coated Dacron tube anastomosed to the anterior aspect of the ascending aorta. The inflow conduit of the cannula is positioned into the left ventricle through the aortic valve, and the end hole of the outflow conduit is positioned in the ascending aorta. The cannula was evaluated in vivo in 3 adult pigs by the institution of a centrifugal pump for left ventricular support. Optimal flow varied between 5 and 6 L/min and mean aortic pressure between 55 and 70 mm Hg throughout the 3 days of left ventricular support. Recently, we employed this cannula in a patient who was not able to be weaned from cardiopulmonary bypass for the institution of left ventricular support using a centrifugal pump. The cannula provided effective inflow and outflow drainage with an optimal flow of 5.2 L/min throughout the 72 h of support. The patient was successfully weaned from support on the fourth postoperative day. This rational transaortic approach of cannulation using this specific cannula is a refined implantation technique which allows direct left ventricular inflow drainage, reduces the time of implantation, spares left ventricular myocardium, avoids bleeding that is sometimes encountered at other cannulation sites, and avoids compression of the heart by cannulas.     

Venous outflow and inflow resistance in health and venous disease

PURPOSE: The purpose of this study was to develop a physiologic method to measure outflow and inflow from the lower extremities and thus to quantify the degree of venous valvular insufficiency and venous obstructive disease. METHODS: Calibrated photoplethysmography was used in combination with passive changes in hydrostatic pressure, by leg elevation followed by repositioning of the leg to the original sitting position. With the principle of venous occlusion plethysmography, timed volume changes were then used to calculate the outflow and inflow. The inflow and outflow units were the percentage of optical reflectance (%OR) per minute. The respective resistances were calculated by identifying the hydrostatic pressure distance from the third intercostal space to the probe site that is inducing these site changes. The resistance units were millimeters of Mercury x minutes per %OR. RESULTS: Four groups of subjects were examined: normal individuals, patients with venous valvular insufficiency, deep venous thrombosis, and a combination of both. The most significant differences in outflow values were found between the control group (81.77% OR/min) and the deep venous thrombosis group (28.47% OR/min). In contrast, the most significant differences in inflow values were found between the control group (9. 67% OR/min) and the venous valvular insufficiency group (108.61% OR/min). The resistances changed correspondingly. CONCLUSION: The application of calibrated photoplethysmography in conjunction with induced changes in leg hydrostatic pressure proved to be an effective physiologic method to noninvasively quantify venous hemodynamics in normal control subjects, patients with venous valvular insufficiency, venous obstructive disease, or both.     

Long term results of autogenous vein bypass grafts in femoropopliteal arterial occlusion

The results of 329 consecutive autogenous vein grafts carried out between January 1962 and June 1973 have been reviewed. The 5- and 10-year mortality rates were 14.6 per cent and 18.7 per cent respectively. The corresponding patency rates were 70 per cent at 5 years and 34 per cent at 10 years, the lowest patency (27.8 per cent) occurring in below-knee anastomoses with grafts of 5 mm or less in diameter. As other have noted, the state of the popliteal--tibial run-off vessels had a considerable influence on long term patency rates. In severely ischaemic limbs, the limb salvage rate following this operation was 77 per cent. An analysis of symptoms, associated disease and complications is presented and discussed. No valid conclusions could be made regarding the effect of lumbar sympathectomy and postoperative anticoagulants on long term patency. This review has confirmed the findings of earlier studies that a satisfactory 5-year patency rate and a gratifying limb salvage rate can be achieved with an extremely low operative mortality rate of 0.37 per cent. Despite the presence of widespread atherosclerotic arterial disease, the 5-year mortality rate is 14.6 per cent, indicating that an attempt at reconstructive surgery is usually well worth while.     

The use of vein grafts in the treatment of peripheral lymphedemas: long-term results

This study evaluates long-term results of the treatment of peripheral lymphedemas by the microsurgical reconstructive technique of interposed vein grafts. The technique consists of the use of autologous vein grafts to reconstruct lymphatic pathways where there is a block to the lymphatic circulation of the limb, whether of congenital or acquired etiology. The venous segment represents a sort of "bridge" between afferent and efferent lymphatic collectors (lymphatic-venous-lymphatic plasty [LVLA]). The results also proved to have positive long-term effects after microsurgical operation. Follow-up evaluation was performed clinically by water volumetry and instrumentally by lymphangioscintigraphy. With this LVLA technique, peripheral lymphedemas can be treated when derivative lymphovenous shunts cannot be used because of impaired venous circulation in the same lymphedematous limb. The new aspect of the study is that we report long-term clinical and instrumental results.     

Use of bovine jugular vein to reconstruct the right ventricular outflow tract: early results

OBJECTIVE: We evaluate early results of bovine jugular vein conduits in the pulmonary outflow. METHODS: Between April 2000 and September 2001, 31 conduits were placed in the outflow of the right ventricle. Patients who received a conduit as a staged surgical procedure were excluded (n = 3). Implantation age ranged from 0 to 21 years (median, 3.4 years). Conduit diameter ranged from 12 to 20 mm (median, 14 mm). Transthoracic echocardiography was performed at discharge and 3 months after surgery. Patients with significant pulmonary regurgitation and/or stenosis underwent cardiac catheterization. RESULTS: Four patients died during the follow-up period. Three deaths were unrelated to the conduit. One death was related to the complete thrombosis of the conduit. At 3 months evaluation, pulmonary valve regurgitation was absent or trivial in 19, mild in 2 and severe in 3 of 24 survivors. Four patients had nonfatal conduit-related complications. A transient thrombus formation within 1 leaflet was noted postoperatively in a patient with a moderate pulmonary regurgitation. Three patients required reoperation 3 to 5.8 months after the implantation for conduit failure (mean, 4.3 months). Cardiac catheterization before replacement revealed an aneurysmal dilation of the conduit below a severe stenosis of the pulmonary bifurcation due to important neointimal proliferation. CONCLUSIONS: Early failure of bovine jugular vein valved conduits can occur because of exaggerated intimal proliferation or thrombotic process within the conduit. Because of these complications, close echocardiographic follow-up is mandatory during the first weeks after implantation.     

预结扎病侧肝脏入出肝血管切肝术的体会

目的　比较预结扎病侧肝脏入出肝血管切肝术与阻断肝门切肝术的优缺点。方法　 32例病人包括两组 :甲组 2 0例 ,肝切除时阻断肝门。乙组 12例 ,肝切除时预结扎病侧肝脏入出肝血管。对两组病人的术中失血量 ,术后平均出血量和引流量 ,术后肝功能恢复时间和术后并发症等进行比较分析。结果　甲乙两组术中平均出血量分别是 85 0ml和 4 5 0ml (P <0 0 1)。术后平均出血和引流量分别是 30 0ml和 15 0ml(P <0 0 1)。术后ALT恢复正常时间分别为 6～ 35d和 3～ 7d ,AST恢复正常时间分别是 5～ 30d和 4～ 8d ,总胆红素恢复正常时间分别为 7～ 6 0d和 5～ 14d ,两组相比差异显著 (P <0 0 1)。术后并发症发生率分别为 30 %和 0 % (P <0 0 1)。结论　预结扎病侧肝脏入出肝血管切肝术优于阻断肝门切肝术     

Experimental microvascular autogenous vein grafts for arterial defects: a study of anastomotic sites

Autogenous femoral vein grafts with an average external diameter of 1.5 mm and an average length of 2.87 cm have been used to bridge defects in the contralateral femoral artery of 15 adult New Zealand white rabbits. An experimental microvascular technique to minimise trauma to the graft was performed, by which clamps were never applied to the graft itself. Patency was assessed over a 12-week period, and the overall graft success rate, excluding one technical failure, was 86%. Each of the three failures resulted from thrombosis. Histologic examination of the patent anastomoses showed marked medial damage at 1 week, complicated by fibrosis and calcification by 4 weeks; thereafter the intima developed prominent fibroelastic thickening. This led to a degree of luminal narrowing by 12 weeks. However, the underlying medial damage, attributable to operative trauma, did not seem to diminish luminal patency.