Stig Ekeström

Early and Late Patency of Aortocoronary Vein Grafts

Early patency (two weeks) of 331 aortocoronary vein grafts was 89%. Late patency (one year) of 122 restudied grafts was 80%. A cumulative one year patency of 72% was calculated. Patency was similar for SV grafts, sutured distal to stenosis and segmental obstruction. Early patency was significantly decreased when the peroperative graft blood flow was 20 ml/min or less or the diameter of the recipient coronary artery was smaller than 1.5 mm. Cumulative one year patency was lower in symptomatic patients (54%) than in those who underwent consecutive reevaluation (80%). There was a trend towards improved patency rates for graft anastomosed to the left anterior descending coronary artery and grafts without pre-existing pathological changes. Patient parameters, such as at operation, sex, smoking habits, hypertension, lipid abnormalities, diabetes, previous myocardial infarction or depressed left ventricular function, had no bearing on patency. Graft failure occurring, despite refined surgical technique, is usually due to pathological changes of the vein graft per se or the recipient coronary artery and its vascular bed.

Decreased Red Cell Deformability Following Open-Heart Surgery

Red blood cell deformability is essential for a normal microcirculation. The effect of extracorporeal circulation on red cell deformability was evaluated with a filtration technique in 25 patients undergoing open-heart surgery. During extracorporeal circulation there was a significant decrease in deformability, by on average 31% (p less than 0.001). No correlation was found between decrease in deformability and duration of the extracorporeal circulation procedure. In a subgroup of patients, deformability was followed also postoperatively. During the first postoperative day there was a further decrease of 17%. By the second to third postoperative days, deformability had decreased by another 23%, so that now it was less than half of the preoperative value. On the fifth to sixth postoperative days the values remained equally low. A reduction in red blood cell damage during extracorporeal circulation may be an important factor for improving nutritional blood flow. This in turn could reduce the number of complications in various organs following open-heart surgery.

Blood Flow After Peripheral Arterial Reconstruction:I. Measurements after lliac-Femoro-Popliteal Arterial Reconstructions with the Electromagnetic Flowmeter and Implanted Flow Probes during Operation and in the Eearly Postoperative Periods

Blood flow has been studied with the electromagnetic flowmeter in 22 patients after reconstruction of the leg arteries during the per- and early postoperative periods with implanted flow probes. Sixteen vein bypasses, 5 superficial femoral arteries and 2 common femoral arteries were studied. The average flow after reconstruction was 215 in the vein bypasses, 210 in the superficial femoral artery and 240, respective, 250 in the common femoral artery. The flow increased during the final phase of operation, and on termination the flow was in average 290 ml/min in the bypass 340 ml/min in the superficial femoral artery and 690 and 705 ml/min, respectively, in the common femoral artery. Repeated measurements were made 24, 48 and 72 hours postoperatively and the changes in flow were studied at rest and during various forms of exercise. The flow decreased during the first postoperative hours. From the afternoon of the day of operation to the next day, the flow at rest increased significantly in the bypass cases ...

Coronary artery reoperations. Early and late results in 101 patients.

Coronary artery reoperation was performed on 101 patients between 1972 and 1985. The resternotomy was associated with major hemorrhage in 12 cases. Of 29 patent internal mammary artery (IMA) grafts, 11 (38%) were damaged during mobilization of the left ventricle. At reoperations performed more than a year after the initial operation, increased graft blood flow compared with the first operation was observed in IMA but not in vein grafts. There were six early deaths (6%). The 5-year survival rate, inclusive of early mortality, was 90%. After a median of 2.5 years, 82% of the patients reported symptomatic improvement and 22% were completely free from angina, but full physical fitness was restored in only 3%. Excluding the patients of retirement age, 35% were able to resume work after the reoperation. Coronary artery reoperation should be considered only for patients with severe angina, because of the increased surgical risk and the lower likelihood of completely relieved symptoms. Presence of a patent IMA graft necessitates special caution.

Indications for the Internal Mammary Artery Graft

Experience of 285 internal mammary artery (IMA) grafts inserted during a five-year period disclosed an operative mortality of 1.5% when patients with associated procedures were excluded. Two of nine patients undergoing concomitant intracardiac surgery died within one month. Thus the overall operative mortality was 2.1%. Preoperative IMA graft blood flow was significantly less than that through comparable aortocoronary saphenous vein grafts. Early IMA graft patency (two weeks) was 95% and the cumulative late patency (one year) was 91%. Early patency for IMA grafts with peroperative flow less than 20 ml was 70%. None of these grafts were occluded at late follow-up. Sixteen occluded IMA grafts were related to technical problems (six grafts), inadequate graft size (five), extensive disease of the recipient coronary artery (four) and to overestimated proximal stenosis with large competitive flow enhancing early graft failure (one graft). Retrograde filing of the IMA when contrast was injected into the recipient coronary artery, was observed in 7 patients (3%). Probable causes were proximal stenosis of the graft, small sized IMA with inadequate antegrade flow and overestimated proximal coronary obstruction. Prerequisites for performing optimal IMA grafting need pre- and peroperative caution. A good calibre IMA without proximal obstructions must be available. The technique of dissecting and handling the vessel and performing anastomosis must be careful. The recipient coronary artery should be selected with consideration in order to avoid unfavourable demand-supply ratios. The IMA is most suitable for low-flow situations supplying a small amount fo myocardium distal to a high-grade coronary obstruction.

Influence of glucose-insulin-potassium on left ventricular function during coronary artery bypass grafting.

To evaluate the hemodynamic effect of glucose-insulin-potassium administered during cardiopulmonary bypass grafting (CABG), i.v. infusion of glucose 0.5 g, insulin 1.35 IU and potassium 0.25 mmol/kg b.w/hour was begun after induction of anesthesia and continued until aortic cross-clamping in seven patients. Seven controls underwent CABG without such infusion. The left ventricular ejection fraction was measured after i.v. injection of Tc-99m-HSA before and at termination of cardiopulmonary bypass (CPB), in conjunction with invasive measurements to obtain left ventricular pressure-volume indices at end-systole and end-diastole. Three-step transfusion from the oxygenator was given before and after CPB in order to assess left ventricular contractility during volume-load, using the end-systolic pressure-volume index. Left ventricular contractility remained unchanged after CPB in the patients given glucose-insulin-potassium but decreased significantly in the controls. The left ventricular passive diastolic properties were unchanged after the ischemic period in both groups. The arterial glucose concentration rose markedly in the infused group (7.3-18.5 mmol/l) and moderately (6.4-8.2) in the controls. Glucose-insulin-potassium infusion thus favorably influenced left ventricular function during CABG by preventing decrease in contractility after CPB.

Adenosine-Induced Increase in Graft Flow During Coronary Bypass Surgery

The influence of systemic adenosine infusion (30-50 micrograms/kg/min) on peroperative coronary graft flow was investigated in 16 patients undergoing bypass surgery. The central hemodynamic and graft flow (electromagnetic flow determination) responses were studied after 5-min, and in nine patients also after 30-min infusion. The low-dose adenosine infusion had little effect on the central hemodynamic parameters, while the graft flow increased in all patients (mean 84 +/- 12%, total 22 grafts). The adenosine-induced increase in graft flow was maintained when the infusion was prolonged. It is concluded that adenosine can produce marked coronary vasodilation in man at infusion rates that exert only minor systemic hemodynamic effects.

Renal artery reconstruction in renovascular hypertension.

Over a period of 8 years, 52 patients (31 females and 21 males) between 12 and 59 years of age (mean age 40 years) underwent renal artery reconstruction for correction of renovascular hypertension. Five patients were operated on bilaterally. A thoracoretroperitoneal approach was chosen at 48 of 57 renal artery reconstructions. The most used types of arterial reconstruction were thrombendarterectomy and vein patch, resection of the stenosis and end-to-end anastomosis, vein patch only or aortorenal vein bypass. No early or late nephrectomies were performed. These was no operative mortality, but 3 late deaths occurred. Twenty-two patients were normotensive postoperatively, 20 were improved and there were 10 failures. The follow-up time as 1--8 years. The blood pressures were measured after withdrawal of antihypertensive drugs for at least 10 days. The best predictable criterion for normotension was a positive renin test with a renin ratio of 1.5 or more. The normotensive patients were in the younger age group with a shorter duration of known hypertension and had mainly fibromuscular hyperplasia.

Effect of Dipyridamole (Persantin®) on Blood Flow and Patency of Aortocoronary Vein Bypass Grafts

The effect of dipyridamole was investigated in 360 patients undergoing coronary bypass surgery. They were randomly allocated to receive dipyridamole (100 mg orally q.i.d. for 2 days preoperatively, 5 mg/kg body weight/24 h i.v. peroperatively and 100 mg orally q.i.d. for 1 year postoperatively) or placebo. Withdrawn from the study were 48 patients on dipyridamole and 57 on placebo. Cardiovascular and/or cerebrovascular events or need for anticoagulant treatment were the reasons for withdrawal in 22 (13%) of the dipyridamole, and 34 (18%) of the placebo group. Logistic regression analysis of risk factors influencing graft patency showed significant relation to peroperatively measured coronary blood flow. A positive trend of treatment was observed (p = 0.08). Vein graft blood flow measured during bypass surgery (245 patients) was significantly greater in the dipyridamole group (p less than 0.01). The occlusion rate was lower in vessels with peroperative blood flow greater than 30 ml/min (vein-marginal p less than 0.01, vein-dexter p less than 0.05, vein-diagonal 0.05 less than p less than 0.1). Dipyridamole increases coronary blood flow and graft patency following coronary bypass surgery.

EARLY MORTALITY AFTER 2 902 CORONARY ARTERY BYPASS OPERATIONS

A review of 2,902 coronary artery bypass grafting operations is presented. During the 16-year study period the mean patient age rose from 51 to 59 years and the average number of grafts per patient from 1.5 to 3.0. There were 81 early deaths (2.8%, the most common cause being myocardial infarction (68%). Left main stem stenosis was present in 23 of these 81 patients and depressed left ventricular function in 30. Compared with the survivors, the deceased patients were characterized by higher age, proportionately large numbers of women, combined procedures and reoperations and less use of internal mammary artery grafts. Of the 94 patients aged greater than or equal to 70, 11 died (12%). The perioperative mortality was significantly greater (p less than 0.05) in women than in men (20/457 vs. 61/2445 viz. 4.4% vs. 2.5%). Combined operations were associated with 8.7% (27/311), reoperations with 6% (6/101) and coronary endarterectomy with 5% (4/75) early deaths. In the last year of the study there were three early deaths among 359 patients (0.8%) who underwent primary isolated coronary bypass grafting without endarterectomy. The perioperative risks fell steadily during 16 years, despite rising proportions of older patients, combined procedures, reoperation and coronary endarterectomy.