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Biomedical subjects

C Olin

Publications and source records attributed to C Olin.

At least 37 records · Page 2Linked to original sources
PubMed1996

An in vivo method for testing hemocompatibility of materials used in prosthetic heart valves.

BACKGROUND AND AIMS OF THE STUDY: An in vivo method for testing hemocompatibility of materials used in mechanical heart valves was developed. METHODS: Discs of test materials were glued to specially designed plastic (Delrin) buttons and implanted into the superior and inferior venae cavae of sheep through a right thoracotomy. The button and disc had such configuration that the blood flow was minimally disturbed. Up to four different materials could be tested simultaneously in each animal: two in superior vena cava and two in inferior vena cava. The materials and their respective implantation sites were changed between different animals according to the Latin square principle. Ten animals were used. Three materials currently used in mechanical heart valve prostheses-titanium, cobalt-chromium alloy (Haynes 25) and pyrolytic carbon (Pyrolite)--together with a surface modified (methylated) titanium were evaluated. No heparin was given during the experiment. After two hours of testing the discs were explanted and evaluated for hemocompatibility. The thrombus area on each disc was measured with photography and planimetry. Platelet and leukocyte adhesion on the surfaces were quantitatively assessed by scanning electron microscopy (SEM). The results showed that there were significant differences in thrombus formation (p = 0.001) and leukocyte adhesion (p = 0.002) between the materials tested. There was no difference between implantation sites but significant differences between individual animals (p < 0.05). CONCLUSION: The results indicate that the method can be used to evaluate early hemocompatibility of biomaterials.

Adhesiveness↗
PubMed1989

Improvements of the lipoprotein profile after coronary bypass surgery: additional effects of an exercise training program.

We have followed physical working capacity and the plasma lipoprotein pattern in 37 males who underwent coronary artery surgery for severe disabling angina pectoris. In order to evaluate the effect of exercise training, 18 patients were randomized to a supervised bicycle training programme three times a week for 12 weeks starting 6 weeks after surgery. Before surgery, working capacity was severely reduced in all subjects. The mean HDL cholesterol level was low (0.8 +/- 0.2 mmol l-1) and the mean plasma LDL concentration moderately elevated (4.6 +/- 0.9 mmol l-1). In the non-training group, physical working capacity increased significantly, and 18 weeks after surgery reached a plateau about 45% above the preoperative values. In the training group, a further improvement to about 60% above preoperative levels was registered at the end of the training program. In the non-training group, HDL cholesterol concentrations rose rapidly to levels between 10 and 15% above the preoperative values. One year after surgery, HDL cholesterol levels were 20% higher than before surgery. There was a parallel rise in apolipoprotein A1 concentrations by about 10% which indicates that the increase in HDL occurred mainly in the lipid rich HDL2 subfraction. There were no changes in plasma lipids or in LDL cholesterol concentrations. In the training group, the increase in HDL was about 20% during the first 26 weeks. One year after surgery, HDL levels were 23% above preoperative values. In this group, we also registered a significant decrease in plasma triglyceride levels by about 25% after two months of exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗
PubMed1988

Diagnosis and management of acute aortic dissection, clinical and radiological follow-up.

A clinical series of acute aortic dissections is presented. Twenty cases were of type A and 10 of type B. Acute severe chest pain was common, in type A also blood pressure difference between the arms and aortic regurgitation. The diagnosis was established by echocardiography, computerized tomography and/or aortography. Antihypertensive therapy was instituted immediately after diagnosis and was in type A cases followed by acute surgery unless definite contraindications existed. Of 14 surgically treated type A patients 13 survived the operation. On follow-up 1.5-3.5 years later, 12 patients were still alive and doing well, but the false channel remained open in all cases where it had not been resected totally. Only one of six conservatively treated type A patients survived. Type B dissections were operated on only if conservative therapy failed. Four of five conservatively and two of five surgically treated type B patients survived.

Adult↗
PubMed1987

The Björk-Shiley 70 degree convexo-concave prosthesis strut fracture problem (present state of information).

Between June 1980 and June 1983 4028 Björk-Shiley 70 degree convexo-concave prosthetic heart valves were distributed and implanted in Australia, Canada, Europe and South Africa. As of March 1986, a total of 52 outlet strut fractures (1.29%; 70% CL: 1.1%-1.5%) have been reported from 29 implant institutions in 12 countries. The majority (82.7%) occurred in Europe. Intervals between implantation and fracture were 13 days to 45.3 months (mean: 18.4 months; 70% CL: 16.6 months-20.1 months). The mortality rate after strut fracture was 78.7% (70% CL: 72.5%-84.9%). Upon stratification of the fracture by valve sizes and types it becomes evident that 75% (70% CL: 68.8%-81.2%) of all fractures are related to the sizes 29 mm to 33 mm (which virtually represent the same valve size) and predominantly to mitral valves (p less than 0.01). The large valves again have been stratified into two subsets, namely those fabricated from flanges originally machined as Björk-Shiley 60 degree convexo-concave valves (group I) and later produced valves machined initially to 70 degree specifications (group II). In group I the fracture rate was 5.2% (70% CL: 4.2%-6.2%) versus 1.6% (70% CL: 1.1%-2.1%) in group II (p less than 0.01), which identifies the group I 29 mm-33 mm Björk-Shiley 70 degree convexo-concave valves as the highest risk group for strut fracture. The rates are based upon all available information as of March 16, 1986.(ABSTRACT TRUNCATED AT 250 WORDS)

Heart Valve Prosthesis↗
PubMed1987

Mediastinal drainage blood. Potentialities for autotransfusion after cardiac surgery.

The rate of postoperative bleeding was studied in 32 patients with aortocoronary bypass surgery and in 18 with aortic valve replacement. In 12 of the 50 patients, more than 500 ml of shed mediastinal blood could be saved within 8 postoperative hours. Aerobic and anaerobic cultures of such blood were obtained from the suction reservoir in 20 cases 2, 4 and 6 hours postoperatively. The results were negative, apart from Staphylococcus albus in one 6-hour sample. The blood, which was in some degree hemolyzed, contained acceptable amounts of red cells and albumin. Alterations of the coagulation and fibrinolytic systems indicated massive proteolysis with degradation of the proteins to an extent that precluded coagulation. This proteolysis had taken place in the mediastinum, resulting in total defibrinogenation of the blood. The authors conclude that in about one-fourth of cases in cardiac surgery, postoperatively shed blood is worth saving for red cell and volume substitution.

Aortic Valve↗
PubMed1987

Postoperative autotransfusion of concentrated drainage blood in cardiac surgery. Experience with a new autotransfusion system.

A new autotransfusion system was evaluated postoperatively in six patients undergoing aortocoronary bypass surgery. A hollow fiber hemofilter was integrated in the system, making it possible to concentrate the shed blood. The device functioned well, 825 ml diluted mediastinal drainage blood with a hematocrit of 23 was concentrated to a volume of 475 ml with a hematocrit of 36 and retransfused. Proteins were preserved, thus albumin concentration increased from 23 to 37 g/l in the autotransfusate. No negative side effects were registered after autotransfusion. A thorough coagulation study after retransfusion did not reveal any sign of activation of the coagulation cascade, nor were there any signs of an increased fibrinolysis.

Aged↗
PubMed1986

Late cardiac tamponade following open-heart surgery. Diagnosis and treatment.

Late cardiac tamponade is a rare but serious complication following open-heart surgery. It occurred in 9 (0.8%) of 1 094 consecutive patients 6 to 13 (median 8) days after operation. Six patients had undergone valve replacement and three coronary bypass surgery. All were on anticoagulant medication postoperatively (median TT index 7%). Early symptoms of cardiac tamponade were nausea and general malaise (present in all 9 cases), whereas classical signs of tamponade such as arterial hypotension and distended neck veins appeared late. The cardiac silhouette was radiographically enlarged in all cases, but this finding was seldom diagnostic. Computed tomography gave the surest diagnosis and permitted quantitative assessment of the fluid in the pericardium. Pericardial needle puncture was effective in temporarily relieving the tamponade, but insertion of a tube by the subxiphoid approach gave definitive drainage.

Aged↗
PubMed1984

Antibiotic prophylaxis in pacemaker surgery--a prospective study.

To evaluate the effect of antibiotic prophylaxis in pacemaker surgery, 100 patients were randomly assigned to a prophylaxis group receiving cloxacillin or to a control group with no antibiotics. Cloxacillin was given intravenously (2 g) 2 hours before operation, followed by 1 g every 6 hours for 2 days and the same dose perorally for 8 more days postoperatively. Adequate plasma concentrations were obtained in all patients. The follow-up time was 1-43 months. The infection rate was 2% (1/50) in the prophylaxis group and 14% (7/50) in the control group (p less than 0.05). The interval from operation to manifest infection was 9-35 days. In the control group the causal microorganism was Staphylococcus aureus in two patients, Staphylococcus epidermidis in two and unknown in three patients. In the only patient with infection in the prophylaxis group, a methicillin-resistant S. epidermidis was isolated. Infection was initially localized to the pacemaker pocket in seven patients, but septicemia developed in one of them and endocarditis in another. In one patient septicemia appeared initially, without local signs of infection. This study suggests that cloxacillin prophylaxis is of value in routine pacemaker surgery.

Aged↗
PubMed1983

Human myocardial and skeletal muscle enzyme activities: creatine kinase and its isozyme MB as related to citrate synthase and muscle fibre types.

Activities of myocardial and skeletal muscle total creatine kinase (CK) and its isozyme MB were related to the oxidative capacity [measured as the citrate synthase (CS) activity] and to the contractile characteristics (estimated as the percentage of type I muscle fibres). Skeletal muscle biopsies were obtained both from physically trained and untrained men and myocardial biopsies from patients subjected to open-heart surgery performed because of mitral or aortic valve disease. Enzyme activities were determined on freeze-dried muscle specimens. The CK-MB activity was about twice as high in trained skeletal muscle as in untrained ones reaching the myocardial level. The total CK activity was about three times higher in skeletal muscle than in myocardium; the myocardium, however, had CS activity 3-4 times larger than that of skeletal muscle. A close correlation was demonstrated between activities of CK-MB on one hand and CS (r = 0.76) or percentage type I fibres (r = 0.83) on the other hand suggesting a connection between CK-MB activity and the oxidative capacity of the cell. This was in contrast to total CK where different regressions were obtained when comparing the myocardium and the skeletal muscle of trained or untrained men. In conclusion, CK-MB activity in trained skeletal muscle in athletes were similar to that in myocardium. CK-MB was related to the oxidative capacity and formation of cellular energy in skeletal and heart muscle.

Adult↗
PubMed1983

Multicentre investigation of myocardial protection with cold cardioplegia.

In order to analyze factors of importance for the efficiency of myocardial protection during open-heart surgery, a study was made of 144 patients undergoing isolated aortic valve replacement with various cardioplegic techniques. The cardioplegia was of Bretschneider type in 54 cases, St Thomas in 31 and Ringer-potassium type in 11 cases. Single or multi-dose blood cardioplegia was used in 11 cases and continuous blood cardioplegia in 30 cases. Local cardiac hypothermia was additionally employed in all patients. The efficiency of myocardial protection was assessed mainly from the incidence of postoperative conduction disturbances, myocardial enzyme release and need for inotropic support. All patients survived the operation. In 20% surgery was followed by transient or persistent disturbance of conduction, in 9% by abnormally increased CK-MB release and in 5% by requirement for inotropic support. Preoperative risk factors such as high age or severe left ventricular (LV) hypertrophy or dysfunction had little influence on the results. Patients in whom aortic stenosis (AS) was dominant in the complex with aortic insufficiency (AS + AI) showed 20-hour postoperative CK-MB enzyme activity twice as high as those with pure aortic insufficiency. The most important factors in myocardial protection were the duration of aortic occlusion and the myocardial temperature during cardioplegia. When the aortic occlusion lasted more than 80 min there was a 32% incidence of conduction disturbances and 20-hour CK-MB activity thrice as high as after shorter occlusion. Patients with mean myocardial temperature below 18 degrees C during cardioplegia invariably had low enzyme activities, which indicated good myocardial protection. The best overall results were obtained in patients operated on during hypothermia at 25-27 degrees C, with single or multi-dose blood cardioplegia and with efficient local cooling of the heart.

Adult↗