Biomedical subjects
S Ekeström
Publications and source records attributed to S Ekeström.
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.
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.
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.
[Coronary vessel surgery performed at the Sophiahemmet shortens waiting lists of patients].
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Strut-fracture of a Björk-Shiley tilting disc valve diagnosed by echocardiography--a case report.
A 40-year-old man with Björk-Shiley valves implanted in the aortic and mitral positions nine months previously presented with central chest pain. Shortly after admission he developed clinical features consistent with left ventricular failure. Fracture of the mitral prosthesis was diagnosed by echocardiography. At emergency operation the outlet strut of the mitral valve was found to be fractured and the disc was in the left ventricle. The patient survived valve re-placement and is in good health four years later.
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.
Effort dyspnea after coronary bypass surgery.
One hundred consecutive patients were followed up for 6-36 months after coronary artery bypass surgery (CABS) for angina pectoris. Of the 98 survivors, 35 reported effort angina. Of the 63 angina-free patients, nine (14%), also had to interrupt ordinary activities such as walking upstairs/uphill, though now because of dyspnea. In exercise tests all nine denied chest pain, the limiting symptom being dyspnea. Chest radiograms were normal in these nine cases, and spirometry was largely unchanged from the preoperative findings (normal in 3 cases). Exercise tolerance was normal or near normal in six patients. The other three underwent pulmonary scintigraphy and cardiac catheterization at rest and during supine exercise. The scintigrams revealed no pulmonary emboli. Catheterization showed hypokinesis and raised pulmonary capillary wedge pressure during exercise in all three patients. The cause of the left myocardial failure was not established. Long-term evaluation of CABS should take into account both effort angina and effort dyspnea.
Effort dyspnea after coronary artery bypass grafting.
Two series of consecutive patients with disabling effort angina were studied prospectively. From the first series, 94 survivors were followed up 9 months after coronary artery bypass grafting. Thirty-five patients (37%) reported that they still suffered from effort angina. Another 26 patients (28%) also used to stop when walking uphill/upstairs but because of dyspnea and 2 (2%) because of leg fatigue. A symptom-limited exercise test performed in 24 of the 26 with dyspnea revealed effort angina in 2 patients and high-degree dyspnea (mean grade 6.6 of 10) in 22. The exercise capacity was less than normal in 16 of these 22 patients. The number of peripheral anastomoses did not differ between the 26 dyspnea patients and the 31 free from effort restriction, nor did the incidence of perioperative infarctions or treatment with diuretics and beta-blocking drugs at follow-up. The second series of 95 survivors confirmed the high prevalence of disabling dyspnea after coronary artery bypass grafting (24%) and showed that it was not predictable. We conclude that physical fitness is restored in less than half the patients undergoing coronary artery bypass grafting.
Evaluation of antiplatelet agents in the prevention of aorto-coronary bypass occlusion.
The cumulative occlusion rates of aorto-coronary artery venous bypass grafts average from 16 to 26% per distal anastomosis within 12 months and about 2% per following year. The potential benefit of oral anticoagulants and platelet inhibitor drugs has been tested to prevent graft occlusion and to retard the atherosclerotic process. Oral anticoagulants started on the third postoperative day do not significantly reduce graft occlusion after 6 months. Among the platelet inhibitor drugs, dipyridamole started before surgery, followed by dipyridamole and aspirin soon after surgery, was the drug regimen with the best results. More randomised double-blind clinical trials are highly desirable to confirm these findings and to resolve the question of relative efficacy and safety for the various drugs reported to have shown benefit when used in combination.
The immediate function of sequential aortocoronary vein grafts to closely adjacent myocardial areas.
Blood-flow measurements were performed in 72 patients after sequential vein grafting (Y-grafting) to LAD and diagonal branches. The mean blood flow in the joint graft was 69 ml/min, i.e. significantly more than the 36 ml/min in one branch when the other was occluded. When one branch was occluded for 10 min (11 patients), there was insignificant increase of the flow through the nonoccluded branch. The mean joint graft flow and branch flow increased insignificantly after administration of dipyridamole. Lower blood flow in one branch of the sequential graft than in the joint graft is due to insufficient collateral system. High rate of flow in the joint graft probably reduces the rate of early and late occlusion.
Effects of pentoxifylline on central hemodynamics in patients with congestive heart failure.
Pentoxifylline, a xanthine derivative with vasoactive and hemorheologic properties, was studied in regard to effect on central hemodynamics in ten patients with congestive heart failure due to aortic or mitral valve disease, mainly in NYHA group III or IV. The drug was infused intravenously in a dose of 4 mg/kg b.w. during a stable hemodynamic situation after valve replacement. The heart rate, systemic blood pressure, central venous and pulmonary artery pressures and cardiac output were recorded, and the stroke volume, cardiac index and systemic vascular resistance were calculated. Significant increase in cardiac output from the baseline value of 4.92 l/min was found 5-10 min (+22.6%) and 25-30 min (+19.5%) after pentoxifylline infusion. Cardiac index similarly increased from baseline, 2.73 dsc-5 (+22.3 and +18.3, respectively). The systemic vascular resistance showed significant decrease at the same intervals (-20.6 and -15.5%). The heart rate and stroke volume were significantly increased after 5-10 min. The systemic mean blood pressure and the pulmonary artery and central venous pressures showed no significant changes. There were no adverse effects of pentoxifylline.
Sequential myocardial depressant and non-depressant anaesthesia for coronary artery surgery.
Patients undergoing coronary artery surgery run a certain risk of developing myocardial infarction in situations with increased myocardial oxygen demand due to e.g. elevations in heart rate and blood pressure. After cardiopulmonary bypass (CPB) there is, however, also the risk of graft occlusion. The present study evaluated the haemodynamic effects of a sequential anaesthesiological technique using halothane 0.5-1.5% in combination with 50% nitrous oxide and droperidol 0.1 mg X kg b.w.-1 before CPB followed by fentanyl 0.2 mg X h-1 in continuous i.v. infusion and diazepam 10-15 mg during and after bypass. Fourteen patients were studied. In seven patients (Group I) halothane was discontinued immediately before CPB and in the following seven patients (Group II) 10-15 min before bypass. The aim was to depress moderately the inotropic state before bypass and to have a normalized myocardial oxygen demand after CPB in order to promote a good flow in the grafts. In Group II mean left ventricular stroke work index (LVSWI) was 0.54-0.79 J X m-2 after bypass as compared to 0.45-0.51 before at comparable filling pressure. Mean left ventricular power index (LVPI) increased from 0.42-0.55 W X m-2 before to 0.73-1.08 after CPB. The patients in Group I showed a similar pattern although with a less marked difference in LVSWI and LVPI values before and after bypass. No correlation was seen between oxygen delivery and oxygen uptake either below or above an oxygen delivery of 15 mmol X min-1 X m-2.
The influence of isoflurane on blood flow in coronary bypass grafts.
The effects of isoflurane on graft blood flow, central hemodynamics and ECG were evaluated in 20 patients during coronary artery surgery in the period immediately after cardiopulmonary bypass (CPB). Intravenous anesthesia with thiopentone, diazepam, fentanyl (continuous infusion), droperidol and pancuronium supplemented with nitrous oxide was used before, and thiopentone and fentanyl were used during CPB. A first measurement of graft flow was performed during fentanyl infusion and the patients were randomly allocated to a control (n = 10) and a study (n = 10) group. In the study group isoflurane was administered in a dose that reduced systolic arterial blood pressure (SAP) to approximately 100 mmHg (13.3 kPa) (inspired concentration 0.5-1.5%) and a second measurement was performed after 30 min. In the control group the infusion of fentanyl was continued. Isoflurane reduced graft blood flow from 52 +/- 5 (mean and s.e. mean) to 40 +/- 5 ml . min-1 (P less than 0.01) concomitant with reductions in SAP, cardiac index, stroke index, left ventricular stroke work index and power index, while these parameters as well as graft flow remained unchanged in the control group. Isoflurane did not produce any change in the degree of ischemia as judged from the ECG. A high blood flow in recently established coronary artery bypass grafts is essential for the prevention of early graft occlusion; therefore the graft-flow-reducing effect of isoflurane has to be taken into consideration when evaluating different anesthetic regimens in the period after CPB.
Negative effects of dihydroergotamine (Orstanorm) on central haemodynamics and aorto-coronary bypass blood flow. An intraoperative study.
Dihydroergotamine (DHE), Orstanorm, because of its strong constrictor action on capacitance vessels, is used in the treatment of hypotension caused by orthostatism or spinal or epidural anaesthesia. Lately Orstanorm has also been used in combination with heparin as prophylaxis against postoperative thromboembolism. In the present study, Orstanorm (0.01 mg/kg b.w.) was given intravenously to 20 patients after coronary bypass surgery. Coronary bypass blood flow, heart rate, systemic mean and systolic blood pressures, right and left atrial pressures, pulmonary artery pressure and cardiac output were measured. Stroke volume, cardiac index, stroke index, systemic and regional myocardial vascular resistance and cardiac work index were then calculated. The results showed that despite increased filling pressures there was no rise in cardiac output, and despite increased cardiac work the bypass flow significantly decreased. The significant increase in regional myocardial vascular resistance found after administration of DHE may explain the absence of expected increase of cardiac output and coronary bypass flow.
Hydroxyethylrutosides during extracorporeal circulation: effect on erythrocyte deformability.
The effect of hydroxyethylrutosides (HR) on erythrocyte deformability was studied in 13 adult patients subjected to extracorporeal circulation, in seven cases for single valve replacement and in six for coronary bypass operations. A single dose of 1.5 g HR was given by slow intravenous injection immediately before the cardiopulmonary bypass. The controls were 13 patients undergoing the same operations but without HR. In the HR-medicated valve group there was only 3% decrease in erythrocyte deformability following extracorporeal circulation, in contrast to a 41% (p less than 0.01) decrease in the control valve group. Among the coronary patients there was no such difference between the HR and the control groups, with deformability decreasing by 21 and 26%, respectively (both significant, p less than 0.05). HR administered before extracorporeal circulation thus had significant prophylactic effect on red cell deformability in patients undergoing valve replacement. Such beneficial action may improve nutritional blood flow, thereby reducing the number of postoperative complications in various organs. With higher doses and/or longer periods of administration, a favorable effect of HR might be possible also in patients subjected to coronary surgery.
The effect of pentoxifylline on impaired red cell deformability following open-heart surgery.
Red blood cell deformability is essential for a normal nutritional blood flow. The effect of pentoxifylline on impaired red cell deformability following open-heart surgery was studied in 25 patients. The controls were 25 patients with equivalent surgery but no pentoxifylline. After 3 days of preoperative peroral pentoxifylline (1 200 mg/day) there was significant (mean 14%) increase of deformability. Intraoperatively, just before extracorporeal circulation, 300 mg pentoxifylline was given intravenously. During the cardiopulmonary bypass there was nevertheless significant decrease in red cell deformability in the test group (by 29%) as well as in the controls (28%). In the first 2 postoperative days there was further decrease in both groups (31% and 26%). Thereafter, however, deformability improved in the pentoxifylline group but showed additional slight decrease in the controls. By the 6th postoperative day the increase in the test group thus was 35%, whereas the controls showed a further 4% decrease. The reduction in deformability from the preoperative to the 6-day value was significantly less in the pentoxifylline group than in the controls. The study proved that red cell deformability is greatly impaired by extracorporeal circulation. Pre-bypass pentoxifylline medication had a significant prophylactic effect by enhancing the postoperative restitution of deformability.
The effect of O-(beta-hydroxyethyl)-rutosides on central haemodynamics during and after aortocoronary bypass surgery.
Clinical use of O-(beta-hydroxyethyl)-rutosides (HR) has been mainly in chronic venous insufficiency, but to some extent also in arterial insufficiency. We investigated the effect of HR on the central circulation in a group of patients undergoing aortocoronary bypass surgery. Measurements were made during operation and on the first postoperative day, both before and after intravenous injection of 15 ml 10% HR (1.5 g). None of the obtained or calculated values for cardiac output, central blood pressures, coronary blood flow, heart rate, stroke volume and systemic, pulmonary and regional myocardial vascular resistance showed significant change following HR injection intraoperatively or postoperatively. We conclude that this intravenous dosage of HR has no adverse effect on central haemodynamics in patients with advanced coronary disease. This suggests that the drug can also be safely used in patients with peripheral arterial disease, as its beneficial effect on nutritional skin blood flow in these patients seems to be due to action on the microrheology of the blood and not to peripheral vasodilatation.