Preoperative risk factors and aorta-coronary bypass graft patency.

The relationship between graft patency and the presence of presurgical prognostic factors was studied in 636 patients who have undergone aorta-coronary bypass operation. We have found a positive correlation between vein graft patency and both coronary artery constriction score (p less than 0.01) and diastolic blood pressure (p less than 0.05). In patients studied up to one year after surgery, high graft patency was associated with both higher diastolic pressures (p less than 0.03) and higher cholesterol levels (p less than 0.001). However, high cholesterol levels also were associated with coronary arterial obstruction. In patients studied more than a year after operation, high constriction scores before the operation were associated with improved graft patency (p less than 0.03). Our findings indicate that short-term prognosis of the grafts is related mainly to hemodynamic variables.     

Homocysteine levels, haemostatic risk factors and patency rates after endovascular treatment of the above-knee femoro-popliteal artery.

OBJECTIVES: To investigate the relationship between plasma homocysteine and other haemostatic variables and restenoses or reocclusions after endovascular treatment of symptomatic atherosclerosis of the above-knee femoro-popliteal artery. DESIGN: Prospective observational study. SETTING: University hospital. PATIENTS AND METHODS: The study included 103 patients (116 limbs), treated with subintimal angioplasty in 58 cases (50%) and with intraluminal PTA in 58 (50%): 39 (34%) patients were treated for critical limb ischaemia. Blood samples for analyses of fasting plasma values of homocysteine, fibrinogen, D-dimer, activated protein C resistance were drawn upon admission. Median follow-up for all procedures was 11 months (range 0-42 months). Outcome events (arterial patency) were defined as > or =50% restenosis or reocclusion in the treated arterial segment. Patency rates were estimated with the product limit method and Kaplan-Meier curves. Variables found to be related significantly to patency were included in multivariate analysis performed with the Cox proportional hazard model. RESULTS: The 1-year cumulative primary patency rate for all procedures was 48%. One-year limb salvage rate in cases of critical ischaemia was 74%. Multivariate analysis demonstrated significant independent associations between patency rates and plasma D-dimer, diabetes mellitus, the nature of the lesion treated (stenosis vs. occlusion) and antithrombotic therapy with aspirin after the procedure. Plasma levels of homocysteine, fibrinogen or activated protein C resistance were not associated with patency rates. Homocysteine levels were higher in patients with critical limb ischaemia than those with intermittent claudication. CONCLUSIONS: Early restenosis or reocclusion after endovascular intervention of lesions in the above-knee femoro-popliteal artery was more frequent following treatment of occlusion (versus stenosis), for patients with diabetes, patients with elevated D-dimer and those without antithrombotic therapy after the procedure. Plasma homocysteine did not appear to influence the outcome of endovascular intervention.     

Homocysteine levels, haemostatic risk factors and patency rates after endovascular treatment of the common iliac arteries.

OBJECTIVES: To investigate the impact of clinical risk factors, plasma homocysteine and haemostatic variables on the results after endovascular treatment of symptomatic atherosclerosis of the common iliac artery. DESIGN: Prospective observational study. SETTING: University hospital. PATIENTS AND METHOD: The study included 139 technically successful interventions in 103 patients. Technical success was defined as < or = 30% residual stenosis as seen on the post treatment angiogram. Blood samples for analyses of fasting plasma values of homocysteine, fibrinogen, D-dimer, activated protein C resistance were drawn upon admission. Median follow-up for all procedures was 22 months (range 0-55 months). Patency was defined as freedom from > or = 50% restenosis or reocclusion. RESULTS: The technical success rate for all procedures was 93%. The 1-year cumulative primary patency rate based on intention to treat was 85%. Multivariate analysis revealed a significant independent association between patency rates and levels of fibrinogen and homocysteine and the nature of the lesion treated (stenosis vs. occlusion). CONCLUSION: The aetiology of restenoses and reocclusions is probably multifactorial. Procoagulant activity, the nature of the lesion treated and homocysteine levels within and above the upper range of normal limits are important risk factors for failure after endovascular treatment of the common iliac arteries.     

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.     

On-pump versus off-pump coronary artery bypass: independent risk factors and off-pump graft patency.

OBJECTIVE: Current knowledge on off-pump coronary artery bypass (OPCAB) generally stems from single surgeons' experience or from series where OPCABs constituted a minor fraction of coronary operations. The present center decided to venture as far into OPCAB as possible during 1999. The present series thus represents the average surgeon's experience. METHODS: During 1999, 533 patients underwent coronary artery bypass grafting using cardiopulmonary bypass (CPB) in 368 and OPCAB in 165 including the circumflex artery (CX) area in 91. Coronary arteriography was performed before discharge in the first 103 OPCAB patients. RESULTS: The CPB and OPCAB groups differed as regards left ventricular ejection fraction (53+/-13 versus 57+/-11, P < 0.0001) and frequency of triple-vessel or left main stem disease (84 versus 32%, P < 0.0001) but were comparable as regards diabetes (12%), prior myocardial infarct (57%), unstable angina (21%), and previous heart surgery (3%). Using multivariate analyses, 30-day mortality (1.3%), P-creatine kinase myocardial band (CKMB) > 80 microg/l (11.1%), re-sternotomy for bleeding (4.5%) or dehiscense (1.7%), transitory cerebral ischemia and stroke (1.7%), supraventricular tachycardia (27.4%), and hospital stay (mean 8 days) were unrelated to off- versus on-pump surgery as well as to OPCAB in triple-vessel disease. CX branches < or = 1mm, > or = 5 distal anastomoses, prior heart surgery, right coronary artery (RCA) branches < or = 1.5mm, 8-21 days old myocardial infarct, female gender, and preoperative acute arrhythmia (among others) were identified as independent risk factors for mortality or increased CKMB in all 533 patients. The latter five risk factors were reproduced in the OPCAB group isolated. The patency in the 103 OPCABs was 95.3, 91.8, and 85.3% in the left anterior descending artery (LAD), CX, and RCA, respectively. Patency was inversely related to diameter of the grafted vessel in the LAD and CX areas, unlike the RCA area. CONCLUSIONS: The results after beating heart surgery were good also in patients with triple-vessel disease, but specific gains relative to on-pump surgery could not be shown. The independent risk factors in the OPCAB group may indicate relative contraindications for OPCAB grafting.     

Microvascular grafts: effect of diameter discrepancy on patency rates

This study examined the effects of diameter discrepancy between interpositional vein grafts within a range of 0.25 to 2 mm. One hundred rats underwent isolation of a 10 mm segment of the femoral artery, from which a 4 mm segment was removed. Venous grafts measuring 8 +/- 2 mm were interposed. The rats were categorized by their graft to artery diameter ratios. Patency was assessed upon completion and 4-6 days postoperatively. All surgical specimens were submitted to the pathology department for microscopic evaluation. Results showed Group I: graft to artery ratio 1:1, patency rate 90% (18/20); Group II: ratio 0.75:1, patency rate 80% (16/20); Group III: ratio 0.5:1, patency rate 60% (12/20), Group IV: ratio 0.25:1, patency rate 20% (4/20); Group V: ratio 2:1, patency rate 60% (12/20). It is concluded that 1:1 venous graft to artery ratios are optimal. When this is impossible, diameter discrepancies should be at least 0.75:1 for acceptable patency rates to be attained in microvascular grafting.     

Microalbuminuria in type 1 diabetes: rates, risk factors and glycemic threshold.

BACKGROUND: The occurrence of microalbuminuria in type 1 diabetes is strongly predictive of renal and cardiovascular disease and is still likely to occur despite improvements in glycemic control. A better understanding of microalbuminuria is required to inform new interventions. We determined the incidence and risk factors for microalbuminuria [albumin excretion rate (AER) 20 to 200 microg/min] in the EURODIAB Prospective Complications Study. METHODS: This is a seven-year follow-up (between 1988 and 1991) of 1134 normoalbuminuric men and women (aged 15 to 60) with type 1 diabetes from 31 European centers. Risk factors and AER were measured centrally. RESULTS: The incidence of microalbuminuria was 12.6% over 7.3 years. Independent baseline risk factors were HbA1c (7.1 vs. 6.2%, P = 0.0001) and AER (9.6 vs. 7.8 microg/min, P = 0.0001) and, independent of these, fasting triglyceride (0.99 vs. 0.88 mmol/L, P = 0.01), low-density lipoprotein cholesterol (3.5 vs. 3.2 mmol/L, P = 0.02), body mass index (24.0 vs. 23.4 kg/m2, P = 0.01), and waist to hip ratio (WHR; 0.85 vs. 0.83, P = 0.009). Triglyceride and WHR risk factors were nearly as strong as AER in predicting microalbuminuria (standardized regression effects of 1.3 for triglyceride and WHR and 1.5 for AER). Blood pressure at follow-up, but not at baseline, was also raised in those who progressed. There was no evidence of a threshold of HbA1c on microalbuminuria risk. CONCLUSIONS: The incidence of microalbuminuria in patients with type 1 diabetes remains high, and there is no apparent glycemic threshold for it. Markers of insulin resistance, such as triglyceride and WHR, are strong risk factors. Systemic blood pressure is not raised prior to the onset of microalbuminuria.     

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).     

Infrainguinal bypass surgery: factors determining late graft patency

The results of 373 infrainguinal bypass grafts, in a single centre, between 1980 and 1988 are reviewed. One hundred and thirty in situ vein (ISV), 47 reversed saphenous vein (RSV), 118 polytetrafluoroethylene (PTFE) and 78 human umbilical vein (HUV) grafts were used. The indications for surgery were disabling claudication in 25 per cent of patients and limb salvage in 75 per cent. In 36 per cent of operations the distal anastomosis was above the knee and in 64 per cent it was below the knee. Overall 5-year patency rates and limb salvage rates respectively were, for ISV (41 and 69 per cent), RSV (62 and 90 per cent), PTFE (31 and 67 per cent) and HUV (29 and 59 per cent). There was no significant difference in patency among these grafts at the above-knee level, but significant differences between vein and prosthetic grafts were evident below the knee (P less than 0.001). Using a proportional hazards model the three factors that consistently correlated with late graft patency were graft type (P less than 0.001), site of distal anastomosis (P less than 0.001) and distal run-off (P less than 0.001). Overall, the results suggest that prosthetic grafts are a suitable alternative to autogenous vein when the distal anastomosis is above the knee, but vein should always be used, if available, below the knee joint.