Göran William-Olsson

Effect of reduced aprotinin dosage on blood loss and use of blood products in patients undergoing cardiopulmonary bypass.

High-dose aprotinin reduces bleeding after cardiac surgery, but has also evoked concern with regard to potential side effects and hospital costs. To evaluate the effects of reduced-dose aprotinin on blood loss and need for blood transfusion, 40 patients undergoing myocardial revascularization were studied (double-blind, placebo-controlled). Postoperative bleeding was reduced by 40% and erythrocyte infusion by 85% in the group given 3 x 10(6) KIU aprotinin (1 x 10(6) as a loading dose before cardiopulmonary bypass, 1 x 10(6) in the priming volume and 2.5 x 10(5)/hour intraoperatively) Aprotinin concentrations during the operation were monitored and maintained above the required level. There were no adverse effects of the drug. Hospital expenditure on blood products was reduced by 51% when aprotinin was used. Our study suggests that aprotinin in reduced dosage diminishes bleeding and requirements for blood products, and that it should be given before, during and after cardiopulmonary bypass.

Glucose and lactate balances in heart and leg after coronary surgery: Influence of insulin infusion

Glucose and lactate balances in leg (representing mainly skeletal muscle) and heart were studied 1 hour after aortocoronary bypass surgery and insulin treatment. Seventeen men were randomized to receive 25 U fast-acting insulin as a bolus injection, followed by continuous infusion of 1 U/kg b.w. for 1 hour, or to serve as controls. In the leg a small glucose uptake was found while the lactate balance was negative. During the study period the lactate release increased further in the control group. In the myocardium no significant extraction of glucose or lactate could be demonstrated. Insulin treatment resulted in a fivefold increment of leg glucose uptake and in significant myocardial glucose uptake. Myocardial lactate balance was also improved by insulin treatment, with fractional extraction increased from 6 to 21%. It is concluded that myocardial carbohydrate metabolism is restricted in the early period after cardiac surgery, and that this seems to result from insulin resistance induced by the surgical trauma.

Control of intraoperative hypertension with isoflurane in patients with coronary artery disease: effects on regional myocardial blood flow and metabolism

&NA; The effect of isoflurane on regional myocardial metabolism and blood flow, when used as an adjunct to fentanyl‐nitrous oxide anesthesia, to control intraoperative hypertension was investigated. Twenty‐two patients with two‐ or three‐vessel coronary artery disease with an ejection fraction >0.5 and on beta‐blockers up to the morning of surgery were studied during elective coronary artery by‐pass grafting. Systemic and pulmonary hemodynamics, and regional (great cardiac vein, GCVF) myocardial blood flow and myocardial metabolic parameters were measured. In 10 patients, both GCVF and global (coronary sinus, CSF) myocardial blood flows were recorded. Measurements were made 1) after induction of anesthesia but prior to skin incision, 2) during sternotomy, and 3) during isoflurane administration after its use to reduce arterial pressure to the presternotomy level. The increase in systemic arterial pressure during sternotomy was due to an increase in systemic vascular resistance accompanied by increases in heart rate, pulmonary capillary wedge pressure, (PCWP) regional myocardial oxygen consumption and extraction, GCVF and total coronary vascular resistance. Isoflurane reduced systemic arterial pressure but not PCWP, to presternotomy levels within 6.9 ± 0.7 minutes at an end‐tidal concentration of 1.5 ± 0.2%. Isoflurane induced a pronounced systemic and coronary vasodilatation and increases in cardiac index, heart rate and regional myocardial oxygen extraction while the GCVF/CSF ratio remained unchanged. While mean regional—MLE% values were not effected by sternotomy, in two patients myocardial lactate production was seen during sternotomy but not during isoflurane. In another two patients, isoflurane induced lactate production. The two latter patients differed from the group as a whole mainly because of their higher heart rates during isoflurane. We conclude that isoflurane may induce myocardial ischemia even in the abscence of hypotension. This in turn may be caused by an isoflurane‐induced reflex tachycardia and not necessarily redistribution of coronary flow. On the other hand, isoflurane may also have beneficial effects on stress‐induced myocardial ischemia.

Effect of high-dose aprotinin on blood cell filterability in association with cardiopulmonary bypass

BackgroundPrevious studies showed that high-dose aprotinin reduces postoperative bleeding in heart surgery and that blood cell rheologic parameters correlate to postoperative bleeding and other complications. MethodsTo evaluate the blood cell rheologic effect of high-dose aprotinin in patients undergoing coronary artery bypass graft surgery, we studied 68 patients (34 receiving high-dose aprotinin during the operation) by use of a microfiltration method to assess blood cell trauma during cardiopulmonary bypass. ResultsIn the control group, red cell filtration rate (RFR, μL/s) values were significantly reduced from a preoperative level of 55.8 to a level of 37.2 on day 1 (P< 0.002) and to a level of 44.5 on day 6 (P< 0.05) after surgery. The respective values for white cell filtration rate (WFR, μL/s) were 17.0, 8.2 (P< 0.002), and 10.0 (P< 0.005). In the aprotinin group, RFR (μL/s) values were reduced, but not as significantly (58.8 preoperative. 48.1 on day 1, P>0.05, and 50.4 on day 6, P>0.05). The respective values for WFR (μL/s) were 17.5, 15.7 (P>0.05), and 15.8 (P>0.05). ConclusionsBlood cell rheologic function, which is known to be an important factor for adequate microcirculation and which when reduced is associated with postoperative morbidity, was shown to be protected by aprotinin in this study.

Influence of Pathologic Blood Cell Microrheology on Myocardial Microcirculation in Cardiac Surgery Using Cardiopulmonary Bypass

A possible link between blood trauma and the myocardial microcirculation was prospectively studied in 27 patients undergoing cardiac surgery. Blood trauma was assessed microrheologically by analysis of gross red cell filtration rate (RFR) and plasma white cell filtration rate (p-WFR). Laser Doppler flow metry (LDF) was used to assess microflow in the myocardium before and after coronary bypass grafting. The LDF% was significantly reduced in the ischemic parts of the myocar dium, by 25% compared with 52% in the nonischemic myocardium (p < 0.01). After grafting, the grafted ischemic myocardium increased the LDF to 55% (p < 0.001) to levels comparable to those of the nonischemic myocardium, but the normal nonischemic, nongrafted myocardium reduced its microflow to 42% (p < 0.02). The RFR taken simultaneously showed a significant reduction by 34% from 45 to 30μL/sec (p < 0.001). The p-WFR fell significantly by 39% from 33 to 20 μL/sec (p < 0.05). The type of operation did not significantly influence the RFR and p-WFR values. There was a positive correlation between the LDF and RFR (r=0.86, p < 0.01) and between LDF and p-WFR (r=0.77, p < 0.01). Surgery with cardiopulmonary bypass (CPB) reduces the microcirculation in the myocardium. The rheology of blood cells is reduced during CPB. Studies to preserve the blood cells and the microcirculation during and after CPB are required.

Effects of alprostadil infusion during extracorporeal circulation on blood rheology and postoperative blood loss

The authors have investigated the effects a low dose of alprostadil (synthetic prostaglandin E1: S-PGI1) infusion during cardiac surgery on blood rheology and postoperative blood loss. S-PGE1 (20 ng/kg/minute) was given to 13 patients undergoing aortocoronary bypass. Another 13 patients who received no S-PGE1 during bypass surgery served as controls. To assess blood rheology, blood samples for red and white cell filterability (RFR and WFR) and for platelet count were collected preoperatively, immediately after the end of extracorporeal circulation (ECC), and twenty-four hours later. Records of blood loss were taken twelve and twenty-four hours postoperatively. RFR, WFR, and platelet counts at twenty-four hours were significantly reduced in the control group as compared with the S-PGE1 group, p = 0.002, p = 0.004, and p = 0.0026, respectively. Concomitantly, the means of the postoperative blood loss at twelve and twenty-four hours were lower in the S-PGE1 group, p= 0.0001 and p=0.0004, respectively. Furthermore, the use of blood transfusion products was significantly less in the S-PGE, group, p < 0.02. These results showed that the use of S-PGE, during ECC preserves blood rheology in association with significant reductions in blood loss and in the need for blood transfusion postoperatively.

PRESSURE IN INTRAMYOCARDIALLY IMPLANTED INTERNAL MAMMARY ARTERIES IN DOGS IN RELATION TO AORTIC PRESSURE AND DEPTH OF THE IMPLANT

Intramyocardial implantation of the left internal mammary artery was made in ten dogs. The distal end of the artery was pulled to the outside of the heart and catheterized. Another catheter was placed in the descend-ent thoracic aorta. Pressures, recorded simultaneously revealed that there is a higher pressure in the implant than in the aorta during a considerable part of the heart cycle. This prevents blood from entering the intramyocardial part of the artery, and may explain the low flows usually recorded in intramyocardially implanted vessels.

The Initial flow in a Myocardial Vessel Implant in the dog

The initial flow in a myocardial vessel implant in dogs was investigated by injecting contrast into the vessel. The contrast did not disappear during 50-90 seconds after injection, which indicates only minimal flow in the implant.

Left Heart Bypass by Means of A Transplanted Hear!: A Preliminary Report

(1) A technique for connecting an auxiliary heart, so that it acts as a temporary left heart bypass, is described. (2) It is shown that the transplanted heart takes over the systemic circulation when the recipient aorta is cross-clamped. (3) The transplanted heart will take over the whole circulation when the recipient heart has ventricular fibrillation. (4) Left heart bypass with a transplanted heart is suggested for treating experimental left ventricular failure.Artificial maintenance of the circulation by means of left heart bypass has been studied for several years (2, 3, 4, 7). Satisfactory application of the procedure is, however, limited by technical difficulties.The aim of this investigation was to carry out a left heart bypass by means of a transplanted heart. This method might be used for long periods, provided that the immunological problems can be solved.

Improved Red Cell Survival in Patients with Chronic Subclinical Haemolysis Due to Artificial Heart Valve: Observations after in Vitro Treatment of the Cells with Potassium Cyanate

Red cell survival was studied with use of Chromium-51 isotope and standard haematologic tests of haemolysis. The study comprised 30 patients with normally functioning single artificial heart valves of various types. They were investigated on 2 or 3 occasions. Red cells labelled with Cr-51 were treated for 30 min with potassium cyanate (0.5 mg/100 ml) in 5% invertose or with only 5% invertose. The mean red cell survival without cyanate treatment was 25 (+/- 4.2) days. Following cyanate treatment this figure improved to 31 (+/-4.8) days. Low-grade chronic intravascular haemolysis was associated with all the valve types. Abnormal results were found in 67% and 62% of the tests in patients with ball-type valve (deBakey and Starr-Edwards, respectively). The figures for tilting disc values (Lillehei-Kaster and Björk-Shiley) were 51 and 45.5%, while Carpentier-Edwards bioprosthetic valves gave 15.5% abnormal test results. The findings thus suggested that ball valves are more haemolytic than tilting disc valves, which in turn are more haemolytic than tissue valves.