Early Graft Occlusion Research Articles

Experimental coronary artery occlusion: relevance to off-pump cardiac surgery.

Mechanical coronary artery occlusion is required for minimally invasive direct coronary artery bypass and off-pump coronary artery bypass surgery. It is important that the method of occlusion be minimally traumatic. Chronic effects of these methods have never been studied. Temporary occlusion of coronaries utilizing suture snare, silastic loop snare, and bulldog clamp was carried out in 12 Yucatan pigs. Three animals each were sacrificed acutely and at 3, 6, and 12 months. The area of occlusion of each vessel was examined by light microscopy and the degree of damage recorded. In the animals sacrificed acutely, there was more damage using the suture snare than with the other 2 methods, but there was minimal damage at longer intervals. There was slight damage acutely and chronically with the bulldog technique. No damage was seen acutely with the silastic loop technique, but some late damage was found. The techniques of coronary artery dissection and occlusion used for minimally invasive and off-pump bypass surgery may contribute to early postoperative graft occlusion.

Bypass to the intracranial internal carotid artery

Extracranial to intracranial internal carotid artery bypass surgery with vein is well described for a number of diverse conditions. They provide high blood flow with good initial patency. However, long term patencies for specific graft types remains unknown. This is an analysis of consecutive interposition saphenous vein bypass cases between the common carotid artery (CCA) and the intracranial internal carotid artery (ICA) where the distal anastomosis was placed end-to-end immediately proximal to the posterior communicating artery in 55 patients undergoing 57 bypass procedures (bilateral in 2 cases). Twenty-five patients underwent grafting for planned vessel obliteration where the pathology required vessel sacrifice. Twenty-eight patients had bypass grafting for stroke risk reduction in the setting of threatening stroke and 4 patients had bypass grafts for emergency revascularisation in the setting of stroke in evolution. Patients were assessed preoperatively and at follow-up with modified Rankin scores. Procedural related complications included a 7% mortality and 7% functional decline. Early graft occlusion occurred in 5% of grafts leading to death in each case. A further patient died of rupture at the distal anastomosis site. In surviving patients, patency was present in 100% at last follow-up (mean 5 years and maximum 11 years) with no patient sustaining new hemispheric ischemic events. One patient developed a delayed asymptomatic stenosis within the vein graft requiring stenting. Because of the high initial management risks this technique of common carotid to intracranial internal carotid artery saphenous vein bypass surgery should be reserved for patients at considerable risk by alternate management. However, once the acute postoperative period is past the bypass appears to be robust and capable of supplying the entire distribution of a normal internal carotid artery.

Tissue loss, early primary graft occlusion, female gender, and a prohibitive failure rate of secondary infrainguinal arterial reconstruction

Purpose: This study tested the hypothesis that a subset of secondary infrainguinal arterial reconstructions show prohibitive failure rates. Methods: Records of 79 consecutive patients, 44 men and 35 women, with a mean age of 60 years, who underwent secondary infrainguinal bypass from 1992 to 2000 at the University of Michigan Hospital, were reviewed. Data were analyzed with life-table analysis, logistic regression, and descriptive statistics. Results: Secondary infrainguinal reconstructions were performed in patients who had undergone earlier ipsilateral bypasses once (n = 35) or twice (n = 44). Among the prior procedures, 68% (n = 54) were done at an institution other than the authors'. Comorbidities included coronary artery disease (72%), tobacco use (77%), and diabetes mellitus (34%), but no patient had hemodialysis-dependent renal failure. Disabling claudication, with average ankle brachial index of 0.48, had been the indication for the primary operation in 77% of cases. Femoral-popliteal bypass was the primary procedure in 67%, with a prosthetic graft used in 62%. The mean patency duration of these earlier bypasses was 25 months. The indication for the final bypass was rest pain or tissue loss in 51% of patients, with an average ankle brachial index of 0.37. The most common procedure was a femoral-distal bypass with autologous vein (63%). Mean patency duration of the secondary bypasses was 30 months. Graft failure within 30 days of operation occurred in 22 patients (28%), and amputation was necessitated in 86% of these patients. The presence of rest pain or tissue loss, when accompanied with a history of early prior graft thrombosis in female patients, correlated with worse mean patency rates, recurrent graft failure (P ≤.05), and a 94% amputation rate. Men in a similar setting incurred a 57% amputation rate. No association of final patency existed with regard to age, number of prior bypasses, conduit types, tobacco use, or diabetes. Conclusion: Secondary infrainguinal bypasses are associated with an increased rate of graft failure and significant limb loss, particularly in those with a history of rest pain or tissue loss, female gender, and early prior graft failure. More appropriate initial operations in carefully selected patients and aggressive postoperative graft surveillance is speculated to improve these outcomes. (J Vasc Surg 2002;35:902-9.)

The effect of anticoagulation therapy and graft selection on the ischemic consequences of femoropopliteal bypass graft occlusion: Results from a multicenter randomized clinical trial

Objective: A recent retrospective study showed that the ischemic consequences of femoropopliteal bypass graft occlusion were more severe with polytetrafluoroethylene (PTFE) than with vein. This study examines this conclusion and whether oral anticoagulation therapy reduces the degree of ischemia after occlusion of PTFE and vein femoropopliteal bypass grafts. Methods: Four hundred two patients who underwent femoropopliteal bypass grafting (233 PTFE and 169 vein) were randomized to a postoperative regimen of either warfarin (international normalized ratio, 1.4 to 2.8) and aspirin (WASA; 325 mg daily) therapy or aspirin alone (ASA) therapy. The grade of acute ischemia at the time of graft occlusion was assessed with the Society of Vascular Surgery recommended reporting standards (I, viable; II, threatened). Early graft occlusions (<30 days) were excluded. Results: There were 100 graft occlusions (67 PTFE and 33 vein) during a mean follow-up period of 36 months (PTFE) and 39 months (vein). Forty-eight patients were randomized to WASA therapy, and 52 were randomized to ASA therapy. The patients were well matched for age, atherosclerotic risk factors, operative indication, and preoperative ankle-brachial index. Overall, a greater percentage of the PTFE occlusions caused grade II ischemia than did the vein graft occlusions (48% versus 18%; P =.005). The ankle-brachial index at the time of graft occlusion was significantly lower in the PTFE grafts than in the vein grafts (0.28 versus 0.45; P =.001). The patients with PTFE who were undergoing WASA therapy at the time of graft occlusion had less grade II ischemia than did those patients who were undergoing ASA therapy (28% versus 55%; P =.057). However, the incidence rate of severe ischemia after graft occlusion remained greater with PTFE grafts and WASA therapy as compared with all the vein grafts (28% versus 18%). The vein graft occlusions had the same incidence rate of grade II ischemia with WASA therapy as with ASA therapy (20% versus 17%; P = 1.0). Conclusion: The ischemic consequences of femoropopliteal bypass graft occlusion are worse with PTFE than with vein. Treatment with WASA therapy lessens the severity of acute ischemia after the occlusion of PTFE graft as compared with ASA therapy but not to the degree seen with vein graft occlusion. Occlusion of femoropopliteal vein grafts is seldom accompanied by severe ischemia and is not improved with WASA therapy. (J Vasc Surg 2002;35:292-8.)

Use of Biochemical Markers of Infarction for Diagnosing Perioperative Myocardial Infarction and Early Graft Occlusion After Coronary Artery Bypass Surgery

Perioperative myocardial infarction (PMI) during coronary artery bypass grafting (CABG) is an important clinical problem because it is closely associated with increased morbidity and mortality. The diagnosis of PMI is, however, associated with several problems. Due to the surgical trauma, the usual indicators of myocardial infarction (pain, ECG changes, and elevated biochemical markers of infarction) have uncertain diagnostic value. The primary aim of this study was to illustrate the levels of the biochemical markers after uncomplicated bypass surgery defined as no clinical or ECG evidence of PMI, and no graft occlusion at 7 days by repeat angiography; and secondarily, to establish biochemical diagnostic discrimination limits for detection of in-hospital graft occlusion. One hundred three patients undergoing elective CABG were closely monitored by serial measurements of creatine kinase (CK)-MB mass, myoglobin, troponin T, and troponin I, and underwent a repeat angiography before discharge. Seven patients had ECG evidence of PMI. Peak troponin T and CK-MB values were significantly higher in these seven patients, although the diagnostic performances of the optimally chosen cutoff levels for diagnosing AMI were fair. Twelve patients had at least one occluded graft shown by repeat angiography. Peak values of CK-MB and troponin T were significantly higher in patients with graft occlusion (52.2 microg/L vs 24.7 microg/L, p = 0.01; and 3.7 microg/L vs 1.0 microg/L, p = 0.05, respectively). By multivariate analysis, a diagnostic discrimination level of 30 microg/L for CK-MB did not reach statistical significance; however, the independent diagnostic value of a cutoff level for troponin T at 3 microg/L reached a level of significance (p = 0.06). We have suggested normal values of four different biochemical markers of infarction after uncomplicated coronary bypass surgery. Patients with in-hospital graft occlusion had higher peak CK-MB and troponin T values. However, the overlap with patients without graft occlusion is substantial, and the patency status in the individual cannot be reliably predicted from these noninvasive tests.

Endothelial integrity and nitric oxide synthase sources are better maintained in saphenous vein harvested by a ‘no-touch’ technique

Abstract Background The saphenous vein (SV) is a commonly used conduit in bypass procedures. Early graft occlusion rates are greater than 20 per cent in both infrainguinal vein grafts and coronary artery bypass grafts (CABGs). Contributing factors include adventitial and endothelial damage, which may reduce nitric oxide availability in grafts. Nitric oxide has important vasorelaxant and thromboresistant properties beneficial to graft patency. Conventionally, during SV harvest, the perivascular tissue is stripped and the graft distended. A ‘no-touch’ technique has been described in which the SV is harvested together with a cushion of surrounding tissue without vein distension. This study compared endothelial integrity and the potential role of nitric oxide synthase (NOS) in segments of SV harvested by the two techniques. Methods SV was harvested from ten patients undergoing CABG. Distal and proximal ends of the SV were harvested using the no-touch technique, while the middle portion was stripped of the adventitia and distended. Sections of SV were cut and endothelial integrity was assessed with CD31 immunohistochemistry and quantified by morphometric analysis. Putative NOS was identified by reduced nicotinamide adenine dinucleotide phosphate (NADPH)–diaphorase histochemistry and autoradiographic localization of [3H]l-NG-nitroarginine binding. Results More dense CD31 staining was seen on the luminal aspect and vasa vasorum of vessels harvested by the no-touch technique. Morphometric analysis revealed a significant reduction in luminal CD31 staining in conventional compared with no-touch grafts (P &amp;lt; 0·05, Student's t test). NADPH staining was almost continuous on the luminal aspect, and was also present in the adventitia of no-touch vessels, compared with poor staining of conventionally harvested vessels. The pattern of NADPH staining corresponded to endothelial cells lining the vessel lumen as well as vasa vasorum and paravascular nerves in the adventitia. Autoradiographic analysis of specific [3H]nitroarginine binding also showed greater binding in the no-touch vessels. Conclusion Endothelial integrity is better maintained by the no-touch technique. NOS sources on the endothelium and adventitia are preserved, suggesting that nitric oxide availability is retained by these grafts. This technique may therefore lead to improved early patency rates of SV grafts in bypass surgery.

Epidural analgesia and arterial reconstructive surgery to the leg: effects on fibrinolysis and platelet degranulation

It has been suggested that the incidence of early graft occlusion after arterial reconstructive surgery to the leg may be decreased by epidural analgesia. This effect may be mediated by the suppression of the usual cortisol response to surgery, which results in increased circulating plasminogen activator inhibitor-1 with consequent adverse effects on fibrinolysis. To investigate this and other potential mechanisms, 30 patients undergoing arterial reconstructive surgery to the leg were randomized to receive either general anaesthesia or general anaesthesia plus epidural analgesia. Post-operative analgesia was provided by morphine infusion or epidural analgesia, respectively. Blood samples were collected at 0, 2, 4, 6, 12 and 24 h, and 2, 3 and 5 days and analysed for cortisol, plasminogen activator inhibitor-1 antigen, interleukin-6 and beta thromboglobulin. The incidence of graft-related and systemic complications was recorded for 30 days. Only one patient developed early graft occlusion that required embolectomy and eventually amputation. There were no significant changes from control values in either group of patients in circulating cortisol, plasminogen activator inhibitor-1 and beta thrombogobulin (a marker for platelet degranulation). Interleukin-6 values increased significantly in both groups after 4 h and remained elevated until day 3. There were no significant differences between the groups in any variable measured. We conclude that any effect of epidural analgesia on early graft patency is unlikely to be mediated by fibrinolysis or platetlet degranulation.

Results of Lower Limb Revascularization from the Descending Thoracic Aorta

The aim of this retrospective study was to substantiate our results of lower limb revascularizations from the descending thoracic aorta. From November 1984 to November 1994, we used bypass grafting from the descending thoracic aorta to revascularize 69 lower limbs in 36 patients, 34 men and 2 women, whose mean age was 61.8 years. Patients were divided into two groups. Group I (primary indications) included 10 patients who had not had any prior lower limb arterial reconstruction. Group II (secondary indications) consisted of 26 patients who had had a prior arterial reconstruction that was either occluded or complicated. There were three early graft occlusions, all of them successfully treated. Complete flaccid, paraplegia occurred in one patient. Five patients presented with one or several late graft occlusions. Two patients had to undergo below-knee amputation, bilateral in one patient. Routine late control of the repair was performed by CT scanning, at a mean interval of 50.8 months. The good results recorded for bypasses revascularizing lower limbs from the descending thoracic aorta make this technique a satisfactory alternative when the abdominal aorta cannot be used.

Haemostatic Function in Patients Undergoing Coronary Artery Bypass Grafting: Peroperative Perturbations and Relations to Saphenous Vein Graft Closure

Vein graft failure remains a major problem after coronary artery bypass grafting. Occlusion in the first weeks usually is caused by thrombosis, whereas intimal hyperplasia and eventually atherosclerotic changes with superimposed thrombus formation underlie subsequent closure. The present investigation was conducted as a pilot study to examine whether perturbations of haemostatic function predispose to early saphenous vein graft occlusion after coronary artery bypass grafting. Pre- and postoperative determinations (performed on the first, third, and sixth postoperative days) of haemostatic factors and inhibitors were related to the presence of graft occlusion assessed by angiography at 3 months after surgery in 100 men undergoing elective coronary artery bypass grafting for stable angina pectoris. Occlusion of one or more vein grafts within three months of surgery occurred in 23 of the 100 patients examined. The percentage increase in plasma plasminogen activator inhibitor-1 activity on the first postoperative day was significantly higher in patients who subsequently were found to have vein graft occlusion ( p<0.05). Otherwise no postoperative haemostatic measurements were found to predict early vein graft closure. A perturbed plasma plasminogen activator inhibitor-1 response to coronary artery bypass grafting tentatively could be added to the vessel-specific factors that remain the main determinants of early vein graft closure.

Preconditioning and proximal ligation did not influence the outcome of direct internal mammary artery bypass grafting in a canine model

The aim of this study was to assess the need for preconditioning and/or exclusion of competitive flow in minimally invasive coronary bypass grafting procedures (MICAB), to prevent early graft occlusion. Eight mongrel dogs (±25 kg) were operated on under intravenous anaesthesia (sodium thiopenthal 15 mg/kg) and maintained with Halothan 1–2% and Pancurorium. A direct anastomosis between the left internal mammary artery and the left anterior descending coronary artery was performed, via anterior distal sternotomy, on the beating heart. Four dogs were preoperatively randomly conditioned by intravenous bolus injection of Diltiazem (0.0025 g/kg) prior to the procedure and after (meanwhile the left internal mammary artery takedown, the proximal coronary artery was snared during 15 min). In the absence of ECG changes or rhythm disturbances, a direct anastomosis of the left internal mammary artery and the left anterior descending coronary artery was performed. In four control dogs, direct MICAB procedure was done without preconditioning. The proximal left anterior descending coronary artery was occluded upstream of the arteriotomy in two dogs from both groups to exclude competitive flow from the native coronary artery. All the procedures were successful, except for one conditioned dog that sustained preoperative transmural anterior myocardial infarction. Cardiac enzymes (CK and CKMB) rose in all groups immediately after the procedure; this was not statistically significant between groups. All survivors were angiographically controlled after 6 to 8 weeks. They showed good patency of all grafts (mean thrombolysis in myocardial infarction-flow equals 2.86). There was perfect matching between the left internal mammary artery and left anterior descending coronary artery in the conditioned and proximal occluded group, which was contrary to the competitive flow in the control groups between the open left anterior descending coronary artery and the left internal mammary artery graft. Permeability of the left internal mammary artery grafts are not influenced by preconditioning nor exclusion of competitive flow in the MICAB technique for the canine model. Graft diameter and flow are merely the result of outflow conditions. In one case, preconditioning was followed by fatal myocardial infarction.

The results of in situ prosthetic replacement for infected aortic grafts

Background: Treatment of aortic graft infection with graft excision and axillofemoral bypass may carry an increased risk of limb loss, aortic stump blowout, and pelvic ischemia. A review of patients with aortic graft infection treated with in situ prosthetic graft replacement was undertaken to determine if mortality, limb loss, and reinfection rates were improved with this technique. Methods: The clinical data of 25 patients, 19 males and 6 females, with a mean age of 68 years (range 35 to 83), with aortic graft infection, treated between January 1, 1989, and December 31, 1998, by in situ prosthetic graft replacement were reviewed. Follow-up was complete in the 23 surviving patients and averaged 36 months (range 4 to 103). Results: Twenty aortofemoral, 3 aortoiliac, and 2 straight aortic graft infections were treated with excision and in situ replacement with standard polyester grafts in 16 patients (64%), or with rifampin-soaked collagen or gelatin-impregnated polyester grafts in 9 patients (36%). Fifteen patients (60%) had aortic graft enteric fistulas, 8 patients (32%) had abscesses or draining sinuses, and 2 patients (8%) had bacterial biofilm infections. Thirty-day mortality was 8% (2 of 25). There were no early graft occlusions or amputations. There was one late graft occlusion. There were no late amputations. The reinfection rate was 22% (5 grafts). All reinfections occurred in patients operated upon for occlusive disease. Only one reinfection occurred in the rifampin-soaked graft group (11% versus 29%, P = NS). Reinfection tended to be lower in patients with aortoenteric fistulas and without abscess. Autogenous tissue coverage provided statistically significant protection against reinfection. There were no late deaths related to in situ graft infection. Conclusions: Patients treated with in situ graft replacement had an 8% mortality and 100% limb salvage rate. Reinfection rates were similar to those of extra-anatomic bypass, but a trend of lower reinfection rates with rifampin-impregnated grafts was apparent. Patients with aortoenteric fistula and without abscess appear to be well treated by the technique of in situ prosthetic grafting and autogenous tissue coverage.

Aprotinin: an update of its pharmacology and therapeutic use in open heart surgery and coronary artery bypass surgery.

Cardiopulmonary bypass (CPB) is associated with defective haemostasis which results in bleeding and the requirement for allogenic blood product transfusions in many patients undergoing open heart surgery (OHS) and/or coronary artery bypass graft surgery (CABG) with CPB. Conservation of blood has become a priority during surgery because of shortages of donor blood, the risks associated with the use of allogenic blood products and the costs of these products. Aprotinin is a serine protease inhibitor isolated from bovine lung tissue which acts in a number of interrelated ways to provide an antifibrinolytic effect, inhibit contact activation, reduce platelet dysfunction and attenuate the inflammatory response to CPB. It is used to reduce blood loss and transfusion requirements in patients with a risk of haemorrhage and has clear advantages over placebo or no treatment. High dose aprotinin significantly reduces postoperative blood loss compared with aminocaproic acid and desmopressin, and decreases transfusion requirements compared with desmopressin. Results are less consistent with tranexamic acid: high dose aprotinin either reduces blood loss significantly more than, or to an equivalent level to, tranexamic acid. A variety of other lower aprotinin dosage regimens consistently result in similar reductions in blood loss to aminocaproic acid or tranexamic acid. Data from clinical trials indicate that aprotinin is generally well tolerated, and the adverse events seen are those expected in patients undergoing OHS and/or CABG with CPB. Hypersensitivity reactions occur in <0.1 to 0.6% of patients receiving aprotinin for the first time. The results of original reports indicating that aprotinin therapy may increase myocardial infarction rates or mortality have not been supported by more recent studies specifically designed to investigate this outcome. However, a tendency to early vein graft occlusion with aprotinin has been shown and care with anticoagulation and vessel grafts is required. No comparative tolerability data between aprotinin and the lysine analogues, aminocaproic acid and tranexamic acid, are available. Comparative tolerability and cost-effectiveness data for aprotinin and the lysine analogues are required to more fully assess their individual roles in reducing blood loss and transfusion requirements in patients undergoing CPB during OHS and/or CABG. However, clinical evidence to date supports the use of aprotinin over its competitors in patients at high risk of haemorrhage, in those for whom transfusion is unavailable or in patients who refuse allogenic transfusions.

Severe Impairment of Graft Flow without Electrocardiographic Changes during Coronary Artery Bypass Grafting

Early graft occlusion after coronary artery bypass grafting may have deleterious consequences. We routinely use transit-time flowmetry after termination of cardiopulmonary bypass, and we report five cases of early graft failure detected by the flowmeter. Electrocardiographic (ECG) changes were seen in only one of these five cases, and none of the patients had low cardiac output or other signs of graft failure at the end of the operation. The cause of graft failure was tagging in one case, rotation of internal mammary artery grafts in two and kinking of vein grafts in two cases. All errors were corrected, and control flowmetry showed normal flow rates after correction. Flowmetry takes less than 10 min, even with multiple bypass grafts. Based on our results, we advocate routine quality control with flowmetry after termination of cardiopulmonary bypass, since ECG changes are insufficient as checks of flow in bypass grafts.

Analyses of coronary graft patency after aprotinin use: Results from the international multicenter aprotinin graft patency experience (IMAGE) trial

Objective: We examined the effects of aprotinin on graft patency, prevalence of myocardial infarction, and blood loss in patients undergoing primary coronary surgery with cardiopulmonary bypass. Methods: Patients from 13 international sites were randomized to receive intraoperative aprotinin (n = 436) or placebo (n = 434). Graft angiography was obtained a mean of 10.8 days after the operation. Electrocardiograms, cardiac enzymes, and blood loss and replacement were evaluated. Results: In 796 assessable patients, aprotinin reduced thoracic drainage volume by 43% ( P < .0001) and requirement for red blood cell administration by 49% ( P < .0001). Among 703 patients with assessable saphenous vein grafts, occlusions occurred in 15.4% of aprotinin-treated patients and 10.9% of patients receiving placebo ( P = .03). After we had adjusted for risk factors associated with vein graft occlusion, the aprotinin versus placebo risk ratio decreased from 1.7 to 1.05 (90% confidence interval, 0.6 to 1.8). These factors included female gender, lack of prior aspirin therapy, small and poor distal vessel quality, and possibly use of aprotinin-treated blood as excised vein perfusate. At United States sites, patients had characteristics more favorable for graft patency, and occlusions occurred in 9.4% of the aprotinin group and 9.5% of the placebo group ( P = .72). At Danish and Israeli sites, where patients had more adverse characteristics, occlusions occurred in 23.0% of aprotinin- and 12.4% of placebo-treated patients ( P = .01). Aprotinin did not affect the occurrence of myocardial infarction (aprotinin: 2.9%; placebo: 3.8%) or mortality (aprotinin: 1.4%; placebo: 1.6%). Conclusions: In this study, the probability of early vein graft occlusion was increased by aprotinin, but this outcome was promoted by multiple risk factors for graft occlusion. (J Thorac Cardiovasc Surg 1998;116:716-30)

Aortoiliac reconstructive surgery based upon the results of duplex scanning

To evaluate whether duplex scanning can replace angiography in patients operated for aortoiliac obstructive disease. Retrospective. Between January 1995 and October 1996, 44 patients underwent vascular surgery of the aortoiliac tract. The study population was divided into two groups; patients operated upon the results of duplex scanning only and patients who also underwent angiography prior to surgery. The additional value of angiography and the differences between both groups concerning unexpected peroperative findings, early postoperative failures and the need for additional radiological or surgical interventions in the first three postoperative months were studied. Duplex scan group: 22 patients were operated upon the results of duplex scanning only. In two patients surgical strategy had to be changed. Early postoperative graft occlusion occurred in one case. A haemodynamically significant graft stenosis within 3 months of surgery occurred in one patient. Duplex/angiography group: 22 patients underwent both duplex scanning and angiography. Six patients underwent diagnostic angiography after failed duplex scanning. In 10 patients angiography was part of percutaneous transluminal angioplasty prior to surgery. In six patients angiograms were performed after successful duplex scanning. Angiography failed in two patients and added information in four of 16 patients. Unexpected findings at operation occurred in four patients. Graft stenosis within 3 months was detected in three patients. After successful duplex scanning information obtained by angiography has only a limited impact on therapeutic decision-making. In the majority of patients vascular reconstructive surgery of aortoiliac arteries can be planned based on duplex scanning only.

Minimally invasive coronary surgery: surgical considerations and assessment of cardiac troponin I.

Minimally invasive coronary artery bypass grafting (MICABG) using internal thoracic artery (ITA) without median sternotomy and cardiopulmonary bypass (CPB) become a viable option for the management of proximal left anterior descending artery (LAD) disease. Recent studies have demonstrated that cardiac troponine I (cTnI), a new highly specific diagnostic marker of cardiomyocyte damage, is a reliable marker of cardiac ischemia during heart operations under CPB. Between February 1996 and April 1997, 14 patients (10 males, 4 females aged 41-68) underwent MICABG with single-vessel bypass grafting for LAD stenosis (n = 9) or occlusion (n = 5). Video-assisted surgery with left anterior mini-thoracotomy was performed in ten patients and vertical parasternal thoracotomy in the other four. cTnI was measured before LAD occlusion (T0), during anastomosis (T1) and 10 min (T2), 6 h (T3), 24 h (T4), 48 h (T5), 72 h (T6) after coronary reperfusion. Assay methods used a specific enzyme-linked immunosorbent autoanalyzer (Stratus) in peripheral venous blood. Control coronary angiography was performed in all patients. There were no operative complications, no reoperations for bleeding. cTnI concentrations were expressed in ng/ml +/- SD. Mean cTnI level was <3.85+/-1 ng/ml (range 0-32.8). Values were: T0 = 0, T1 = 0.5+/-0.1, T2 = 1.15+/-0.2, T3 = 2.16+/-0.6, T4 = 1.5+/-0.3, T5 = 0.6+/-0.02, T6 = 0.4+/-0.01. Angiography showed patent grafts in 12 patients. A 'no flow situation' was demonstrated in a cardiac symptom-free patient, with reestablishment of flow on repeat angiogram at 6 months. In the other case, early ITA graft occlusion in a patient with two-vessel disease was correlated with a higher cTnI concentration (17.8 ng/ml). Percutaneous angioplasty was performed on the right coronary artery, complicated with dissection and cardiac failure. This patient died 3 months after the MICABG despite ventricular assist device. cTnI did not increase during and after coronary artery occlusion and local immobilization of the heart. It can be used to evaluate postoperative myocardial damage on the beating heart using MICABG.

Long-term graft patency rates and clinical outcomes after revascularization for symptomatic traumatic internal carotid artery dissection.

Surgical management of traumatic internal carotid artery (ICA) dissection remains controversial. Therefore, the delayed outcomes and graft patency rates of patients who underwent bypass procedures for symptomatic traumatic ICA dissection were studied. Between September 1989 and August 1996, 13 patients (9 male and 4 female patients; mean age, 30.6 yr) underwent 16 revascularization procedures for symptomatic traumatic ICA dissection. The duration of clinical follow-up averaged 47.3 months (range, 12-94 mo) from the date of diagnosis. The duration of radiographic follow-up (catheter or magnetic resonance angiography, duplex Doppler ultrasonography) averaged 24 months (range, 12-60 mo). ICA dissection was caused by blunt (n = 11) or penetrating trauma (n = 2). Associated angiographic abnormalities included seven ipsilateral ICA occlusions, six dissecting aneurysms, two carotid-cavernous fistulae, and six contralateral traumatic ICA dissections. Patients requiring early revascularization (n = 6) underwent bypass procedures an average of 19.2 days after their injuries. Medically managed patients who developed ischemia later were revascularized a mean of 7.8 months after injury. The mean Glasgow Coma Scale score at the time of presentation was 10 (range, scores of 6-15), and the mean Glasgow Coma Scale score before revascularization was 14 (range, scores of 9-15). There were 14 saphenous vein ICA bypasses (8 cervical-to-petrous, 3 cervical-to-middle cerebral artery, 3 petrous-to-supraclinoid) and 2 superficial temporal artery-to-middle cerebral artery bypasses. There was one early postoperative graft occlusion, which responded to surgical thrombectomy. One patient with multiple other traumatic injuries died as a result of a pulmonary embolus 12 months after revascularization. All remaining patients had Glasgow Outcome Scale scores of 5, with patent bypass grafts confirmed during follow-up. Revascularization for persistently symptomatic traumatic ICA dissection eliminated ischemia and was associated with excellent long-term outcomes and graft patency rates.

Clinical Results of Infrainguinal Bypass Using Plasma TFE™ Vascular Graft

Twenty-eight infrainguinal bypasses using woven polyethylene terephthalate (PET) vascular graft coated with tetrafluoroethylene (TFE) were evaluated. Distal graft anastomoses were performed to the above-the-knee (AK) popliteal artery in 18 limbs, belowthe-knee (BK) popliteal artery in three limbs, and tibial arteries in seven limbs. No early graft occlusions (within 30 days) occurred in femoropopliteal (FP) bypasses, whereas 5/7 (71%) femorotibial (FT) bypasses occluded postoperatively within five days. During 3 years of follow up, 11 occluded and six failing grafts were detected in the FP bypass group. Average patency times for AK FP, BK FP, and FT bypasses were 619.0 4.5, 226.0 ± 23.0, and 43.4 ±4.5 days, respectively. The cumulative patency rates for AK FP bypass were 81.6 ±.6% at 8 months and 66.7 ±12.3% at 1 year. Seventeen limbs with occluded or failing grafts disclosed six anastomotic stenoses in five (29%) grafts, occlusive lesions in three (18%) inflow and three (18%) outflow host arteries, and thrombosis of two (12%) inflow bypass grafts. No significant lesions were detected in four (23%) occluded grafts following thrombolytic therapy. The results indicated that this graft has acceptable antithrombogenicity in FP position because of no early graft occlusion, and the common causes of graft failure were anastomotic stenoses and occlusive lesions of the host artery.

Preoperative thromboxane A 2/prostaglandin H 2 receptor activity predicts early graft thrombosis

Purpose: This study was carried out to determine whether early failure of infrainguinal bypass grafts is associated with increased expression of platelet thromboxane A 2/prostaglandin H 2 (TXA 2/PGH 2) receptors. A prospective correlation of preoperative platelet TXA 2/PGH 2 receptor-mediated activity with lower extremity graft patency was sought. Methods: Twenty-five patients who underwent infrainguinal bypass surgery for limb salvage were studied at an inpatient academic tertiary referral center and Department of Veterans Affairs Medical Center. Outcome measures were primary graft patency rate at 3 months, platelet TXA 2/PGH 2 receptor activity by equilibrium binding with 125I-BOP, and aggregation to the TXA 2-mimetic U46619. Results: Preoperative platelet TXA 2/PGH 2 receptor density was higher (B max, 3100 ± 1300 vs 1500 ± 1100 sites/platelet [mean ± SD]; p = 0.004) in the five patients who had graft thrombosis within 3 months. The EC 50 for U46619 was lower (26 ± 6 nmol/L vs 57 ± 30 nmol/L; p < 0.05) in these patients as well, confirming the functional effect of the increased receptor density. Early graft thrombosis was more likely in patients with a platelet TXA 2/PGH 2 receptor density greater than 3000 sites/platelet (odds ratio, 76; 95% confidence interval, 3.9 to 1500) or an EC 50 for U46619 less than 30 nmol/L (odds ratio, 16; 95% confidence interval, 1.4 to 180). Conclusions: Elevated platelet TXA 2/PGH 2 receptor levels and enhanced sensitivity of platelet aggregation to TXA 2 predict early arterial graft thrombosis. Specific TXA 2/PGH 2 receptor antagonism may prevent one of the mechanisms that contributes to early graft occlusion. (J Vasc Surg 1998;27:317-28.)

Coagulation Factor V (Arg506 → Gln) Mutation and Early Saphenous Vein Graft Occlusion after Coronary Artery Bypass Grafting

The factor V (Arg506-->Gln) mutation confers an increased risk of deep vein thrombosis, whereas its role in saphenous vein graft closure after coronary artery bypass grafting (CABG) remains unclear. This study examined the anticoagulant response to activated protein C (APC ratio) in relation to the surgical trauma and the significance of the factor V Leiden mutation in determining postoperative thrombin generation and fibrin formation and the risk of early vein graft occlusion. A total of 108 men undergoing elective CABG for exertional angina pectoris (mean age 61.1 +/- 8.7 years) were examined. The patency of saphenous vein grafts was studied at routine reangiography three months after CABG. Of 100 patients who underwent reangiography, 23 had one or more occluded vein grafts at reangiography. Heterozygosity for the factor V (Arg506-->Gln) mutation tended to be associated with early saphenous vein graft occlusion (5/11 carriers vs. 18/89 non-carriers with graft occlusion, chi2 = 3.52, p = 0.06), whereas pre- and postoperative APC ratios did not. Pre- and postoperative determinations of prothrombin fragment 1+2, thrombin-antithrombin complexes and soluble fibrin levels did not differ between patients with and without the mutation. Early saphenous vein graft occlusion after CABG could tentatively be added to deep vein thrombosis as a vascular complication that can be attributed to the factor V (Arg506-->Gln) mutation.