Internal mammary artery grafts: technical factors influencing patency

Eight hundred fourteen patients with internal mammary artery (IMA) coronary artery bypass grafts have been restudied 961 times with coronary arteriography, primarily to evaluate the patency of the grafts in the setting of symptomatic coronary occlusive disease. Their records were reviewed to assess graft patency as related to the technical aspects of coronary artery bypass surgery. Patency was evaluated using life-table analysis of the data. The method of harvesting the IMA played no role in patency. The left anterior descending coronary artery was the recipient coronary artery with the highest patency rate. The left IMA had a significantly higher patency rate than the right IMA. As a group, the IMAs had a significantly higher patency rate than saphenous vein grafts. However, there was no difference between right IMA grafts and saphenous vein grafts. The mammary artery grafts that remained patent throughout the study had a significantly higher blood flow after bypass than did those that became occluded (43.0 +/- 0.9 versus 28.9 +/- 1.8 ml/min; p less than .001).     

A comparison of the late patency rates of axillobilateral femoral and axillounilateral femoral grafts

A total of 130 axillofemoral grafts were peformed in 120 patients from 1966 to present; 66 were axillobilateral femoral moral and 64 were axillounilateral femoral grafts. The average patient age was 66 years. The indications for operation were occlusive disease with rest pain or gangrene in 102 patients, severe claudication four, and bypass of a thoracic aneurysm in one. The one month operative mortality rate was 8 percent (ten patients). Four deaths occurred in elderly patients operated upon as emergencies with acute aortic occlusion. In the 126 elective cases, there were six postoperative deaths (4.7 percent). Twenty thrombectomies were performed in 15 axillobilateral femoral grafts of which 15 (75 percent) were successful. In the unilateral grafts there were 25 thrombectomies in 22 grafts, of which only eight (32 percent) were successful. The 5 year patency rate by the life-table method was 74 percent for axillobilateral femoral grafts and 37 percent for axillounilateral femoral grafts. This difference in patency rates is statistically significant (p < 0.01). Average flow measured by electromagnetic flow meter in six axillobilateral femoral grafts was 621 c.c. per minute and in 11 unilateral femoral grafts was 273 c.c. per minute. We attribute the higher patency rate in axillobilateral femoral grafts to this increased flow. These data indicate that axillobilateral femoral grafts may be performed with anticipation of a 5 year patency rate comparable to that with conventional aortoiliac reconstruction and that axillobilateral femoral grafts should be performed in preference to axillounilateral femoral grafts in poor-risk patients requiring extra-anatomic bypass for aortoiliac occlusive disease.     

Effect of desmopressin on vein graft patency in a microvascular model

Desmopressin acetate decreases blood loss after cardiac surgery by activating platelets. We studied whether this effect was detrimental to small-caliber vein grafts in rats. Thirty minutes before femoral artery grafting with 0.75-mm-diameter reverse autogenous saphenous vein grafts, 20 rats received desmopressin acetate intravenously at 1.0 micrograms/kg over 10 minutes, and 20 control rats received normal saline intravenously over 10 minutes. In each group, 10 rats received a 6-mm-long graft and 10 an 18-mm-long graft. Graft patency was evaluated at 20 minutes, 24 hours, and 30 days. Intimal thickening was assessed by light and scanning electron microscopy. At 30 days, 9 short grafts and 8 long grafts in the desmopressin-treated group were patent, whereas only 8 short control grafts and only 6 long control grafts were patent. Intimal thickening and platelet deposition were the same in both groups. These data show no detrimental effects of desmopressin acetate on saphenous vein graft patency.     

Rat tail replantation as a training model for microvascular procedures of digit replantation

In this study we sought to evaluate the potential of rat tail replantation as a tool for very-small-vessel microvascular anastomoses. We used 10 adult Sprague-Dawley rats. The tail was completely amputated 2.0-cm distal to the base of the tail. Then the tail was replanted with anastomoses of two superficial dorsal veins from both sides and one artery. All 10 replanted tails were pink, viable, and normal-appearing at all daily inspections performed from the first to the fourteenth postoperative days. This model can provide a training tool for the acquisition of superior microvascular surgical technique for the repair of very small vessels that stimulate digital replantation. © 1998 Wiley-Liss, Inc. MICROSURGERY 18:364–367, 1998     

Does remote sepsis influence the patency of microvascular anastomoses?

A pyogenic abscess, even though remote from the artery, significantly increases the occlusion rate of microvascular arterial anastomoses in the rat experimental model.     

Analysis of factors influencing early patency of saphenous vein grafts

To determine factors affecting early patency of saphenous vein grafts, 140 grafts in 65 patients were studied angiographically within 2 months after operation. Twenty of the 140 grafts were occluded. Sixteen variables were extracted from the angiographic findings, intraoperative measurements, clinical characteristics, and biochemical data. The univariate and multivariate analyses were performed to assess their predictive value. Of 16 variables, 3 (coronary artery internal diameter, graft flow, and coronary artery resistance) correlated significantly with graft patency in the univariate analysis. The multivariate analysis selected coronary artery resistance, coronary artery internal diameter, and degree of proximal stenosis as predictors of early graft patency. Of these 3 factors, the coronary artery resistance influenced graft patency mostly. Therefore, the coronary artery resistance was considered to be the most reliable predictor of early graft patency.     

Rat tail: A useful model for microvascular training

The rat femoral vessel model is widely used as the basic model for microvascular training; however, it offers only a limited number of anastomoses and vessel sizes. Rat tail vessels provide long length, almost as long as the tail; adequate diameters, from about 1 mm to 0.2 mm; as well as the economy and a convenient location for practicing microvascular anastomoses. It is also the best choice for anastomosing vessels smaller than 0.5 mm diameter. Using stored, frozen tails harvested from sacrificed rats of other projects makes it even more frugal and convenient. Hence, it is an ideal model for microvascular training. The related anatomy and dissecting method are described and discussed. © 1995 Wiley-Liss, Inc.     

Efficacy of Viabahn in the treatment of severe superficial femoral artery lesions: which factors influence long-term patency?

PURPOSE: To evaluate superficial femoral artery (SFA) occlusive disease treatment by means of covered stents. STUDY DESIGN: retrospective. METHOD: From 2000 to 2005, a Hemobahn/Viabahn endoprosthesis was implanted in 102 limbs (95 patients; mean age: 72.1 years, 52-94) for intermittent claudication (group I, n=50 limbs), critical (group II, n=32) or acute ischemia (group III, n=20). Lesions treated were Trans-Atlantic Inter-Society Consensus (TASC) A (n=9) B (n=42), C (n=28) or D (n=23), associated with a good (2 or 3 leg arteries, n=60) or a poor (1 or 0 artery, n=42) runoff. RESULTS: The endograft was placed successfully in all cases, but 3 early deaths (3.2%) (1 in group II and 2 in group III), and 4 acute thromboses (4%) occurred. Primary and secondary actuarial patency rates were 97+/-1.7%, and 99+/-1% at 1 month, 74+/-4.8% & 84+/-4.1% at 1 year,and 71+/-9.5% & 79+/-8.5% at 3 years, after a mean follow-up of 30.2 months (1-60). Long-term primary and secondary patencies were significantly different between TASC Cand TASC D lesions (P<.004 & .001). CONCLUSION: Severity of lesions, rather than preoperative symptoms or runoff, is mainly to be considered before using Hemobahn/Viabahn endoprosthesis in severe SFA occlusive lesions.     

One millimetre polytetrafluoroethylene (Gore-Tex) as a microvascular prosthesis: technique and early patency

We have described a technique for grafting 1 mm internal diameter polytetrafluoroethylene (Gore-Tex) to the rat femoral artery. By spatulating the ends of the recipient artery and completing the proximal anastomosis before commencing the distal one, gentle and accurate suture placement is assured. At a mean of 40 days postoperatively (range 35-42 days) 16 of 20 Gore-Tex grafts (80%) were patent compared with 17 of 20 autogenous femoral vein grafts (85%). Examination of the prosthetic grafts by light microscopy and scanning electron microscopy showed incomplete development of a cellular lining and some areas of neo-intimal hyperplasia. One millimetre Gore-Tex provides excellent early patency as a microvascular graft in this experimental setting but long term patency is still undetermined.     

Reconstruction of ureteral defects with microvascular vein grafts in a rat model

This study was undertaken to test the performance of an autologous vein graft as a ureteral replacement in the rat model. Twenty-six rats were divided into three groups. In Group 1 (n = 10), the animals had a 3-mm segment of the ipsilateral ureter excised and the ureteral defect repaired, using a superficial epigastric vein graft. In Group 2 (n = 10), the same ureteral defect was created and again repaired, using a superficial epigastric vein graft, with the addition of a Silastic stent. The control, Group 3 (n = 6), had the ureter transected and repaired solely by means of primary anastomosis. Animals from each group underwent urography and were sacrificed for histology at three different postoperative intervals: 1, 4, and 12 weeks. Postoperative urography results showed normal renal function in the animals with ureteral reconstruction using vein grafting aided by a stent, as well as in those with primary ureteral anastomosis. No renal function return was seen in the animals with ureteral reconstruction by vein grafting alone, without stent support. Histologically, a progressive loss of the vascular endothelium, and replacement with the urothelium typical of the ureter, was seen in the stented vein grafts. Severe ureteral obstruction at the proximal site of the graft and hydronephrosis were seen in the vein-graft group without stenting. This study demonstrates that autologous vein grafts can be used successfully to correct a ureteral deficit, contingent on accurate microsurgical technique and immediate stenting.     

Rat intercostal nerves as experimental nerve grafts

In this study, we dissected and measured both sets of intercostal nerves including lengths, diameters, and axon counts in 12 adult rats to provide data applicable to experimental nerve graft research. Dissections showed that total lengths of intercostal nerves from the spinal bifurcation to their last arborizations near the midline ranged from 10 to 89 mm, and diameters ranged from less than 0.1 to 0.5 mm from the thinnest to the thickest part. The segment of easiest dissection was the part between the spinal bifurcation and the lateral cutaneous branch. This part was 4–27 mm (mean, 13.3 mm) long and had an almost constant diameter of 0.18–0.5 mm (mean, 0.32 mm). Counts ranged from 201 to 566 axons/nerve. The segment proximal to the lateral cutaneous branch was the most convenient part to be harvested as a nerve graft, especially in the 8th to 12th intercostal nerves. These nerves could serve as sources for experimental grafts. © 1996 Wiley-Liss, Inc.     

Cold stored femoral vessels as microvascular allografts: A preliminary study

Cold stored femoral arteries or veins have been reinserted successfully as autografts into rabbits. The present study examines whether grafting with cold stored vascular allografts is equally successful. Rabbit femoral arteries and veins were stored at 4°C for 4 weeks before insertion as allografts into unrelated animals. Three weeks after insertion into the femoral artery all venous allografts and 80% of arterial allografts were patent, but patency of both graft types declined over the next few weeks. A small number of cold stored venous allografts when inserted into the femoral vein occluded within 3 weeks. No histological evidence of rejection was apparent. The findings suggest that cold stored vascular allografts could be used successfully as an arterial “prosthesis” to support free flaps where relatively short term patency is required until the flap can establish sufficient peripheral inset to survive in its own right. This technique could be applied when autologous veins are not available or not justified. © 1994 Wiley-Liss, Inc.     

Ticlopidine versus aspirin and dipyridamole: influence on platelet deposition and three-month patency of polytetrafluoroethylene grafts

In an attempt to establish a specific drug regimen that would retard neointimal fibrous thickening (NFT) and promote patency of small arterial grafts, we studied acute platelet accumulation and 3-month patency of 4 mm polytetrafluoroethylene (PTFE) grafts in dogs treated with oral aspirin (2 mg/kg/day) in combination with dipyridamole (5 mg/kg/day) (ASA/D) or ticlopidine (25 mg/kg/day) (T). After 3 days of treatment, 15 dogs were given indium 111-labeled autologous platelets and then had bilateral femoral artery grafts placed (control, 10 grafts; each drug group, 10 grafts). The calculated graft radioactivity expressed as average counts per 10 minutes +/- standard error of the mean (SEM) was as follows: control = 542,003 +/- 63,991; ASA/D = 135,163 +/- 14,443 (p less than 0.001, Student's t test); T = 104,650 +/- 14,004 (p less than 0.001). Bilateral femoral artery and carotid artery grafts were placed in 15 other dogs (control, 20 grafts; each drug group, 20 grafts). Three months later the 60 grafts were excised and their patency recorded: control = 20% (4 of 20 grafts); ASA/D = 70% (12 of 17 grafts) (p less than 0.01, chi-square analysis); T = 30% (6 of 20 grafts) (p greater than 0.05). Mean anastomotic NFT +/- SEM of each graft was measured with an ocular micrometer: control = 1.6 +/- 0.2 mm; ASA/D = 0.7 +/- 0.2 mm (p less than 0.001, Student's t test); T = 1.3 +/- 0.2 mm (p greater than 0.1).(ABSTRACT TRUNCATED AT 250 WORDS)     

Rat epigastric pedicle model: a clinically relevant evaluation of 1-mm PTFE grafts

Twenty-eight Sprague-Dawley rats had 1.0-mm polytetrafluoroethylene (PTFE) interposition grafts placed in their femoral artery that supplied a 3.0 X 3.0 cm epigastric pedicle flap. The model is the first to evaluate 1.0-mm PTFE under rigorous, clinically simulating conditions. Anastomoses employed a new, continuous telescoping suture technique. Grafts were selected for histological and electron microscopic evaluation, which confirmed the development of a cellular neointimal lining. Viability of the flap model had a 90% correlation with graft patency. Overall graft patency was 50%. Patency was documented in some specimens harvested at 200 days. The flap model is a good indicator of graft patency. PTFE grafts of 1.0-mm internal diameter are not yet equivalent to autologous veins. Future refinements, particularly aseptic technique, are expected to result in even higher patency rates.     

An experimental study of microvascular technique, patency rates and related factors.

Microvascular repairs of 50 rabbits' femoral arteries averaging 0.9 mm in diameter gave an immediate patency rate of 100 per cent and a follow-up patency rate of 98 per cent after 3-41 days. The patency rate of 50 veins averaging 1.1 mm in diameter was 98 per cent immediately after surgery and 80 per cent after 3-41 days. No anticoagulants or antispasmodics were used. An additional 25 vein repairs with sufficient additional sutures to ensure more accurate apposition of the vein edges resulted in 100 per cent immediate patency and 92 per cent patency when examined during the 2nd week, the period which reveals the truest patency rate. Technical adequacy of the microvascular repair is the most important factor in ensuring final patency.     

Rat penis as a replantation model

The aim of this study is to assess the feasibility of rat penile replantation as a new microsurgical training model. The study was performed in 2 parts. ANATOMIC STUDIES: Fifteen Wistar albino rats were used to study and document the penile vascular anatomy. In 5 rats, dissections were performed after colored silicone injections, while 5 rats were operated under anesthesia to develop the strategy of flap elevation. In the remaining 5 rats, microangiographic study was performed with silicone-lead oxide mixture. FLAP STUDIES: As flap studies in 5 rats, penis were elevated based on right-side internal pudendal artery and internal pudendal vein and resutured. In 6 rats, penis were elevated as free flaps, and in 3 rats the penis were implanted in right thigh of the rats being the femoral artery and vein recipient. In the remaining 3 rats, penis were resutured in their original place, with saphenous artery and vein being the recipient and rerouted to the pubic region. At postoperative fifth day, the penis were examined for viability, and selected ones were histologically examined. Rat penis has a dual blood supply from bilateral internal pudendal arteries. Venous drainage is via both crural veins and dorsal vein. One side of the internal pudendal artery and anastomotic vein (branch of pudendal plexus) may be used as the vascular pedicle of the flap. Rat penis may be successfully elevated as a free flap and also may be replanted in its original place.     

Smoking and the patency of lower extremity bypass grafts: a meta-analysis

OBJECTIVE: Smoking is the major risk factor associated with the development and progression of peripheral arterial disease (PAD). To establish the best estimate of the effect of smoking, smoking cessation, and the dose-response relationship on the patency of lower extremity bypass grafts, we performed a systematic review. METHODS: A search of medical articles and reviews relating to the influence of smoking on the patency of arterial reconstructive grafts in patients with PAD was made. Studies considered for inclusion were those that evaluated the influence of smoking on the primary, secondary, or cumulative patency rates of arterial reconstructive surgery in the lower extremities in patients with PAD. Primary data were used to calculate summary estimates with standard meta-analysis techniques. RESULTS: The 29 eligible studies included 4 randomized clinical trials, 12 prospective studies, and 13 retrospective studies. The effect of smoking on graft patency in the randomized clinical trials and other prospective studies had a 3.09-fold (2.34 to 4.08; P < .00001) increase in graft failure. A comparison of patency rates among all studies that used autogenous or polyester grafts showed no difference. A clear dose-response relationship was present, with a decreased patency in heavy smokers compared with moderate smokers. Smoking cessation restores patency rates toward the never smokers group. CONCLUSION: Continued smoking after lower limb bypass surgery results in a threefold increased risk of graft failure. Smoking cessation, even if instigated after the operation, restored graft patency towards the patency of never smokers. These results indicate that adequate smoking cessation strategies in patients eligible for lower limb bypass surgery are of utmost importance.