Hans Öhlin
Lund University
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Featured researches published by Hans Öhlin.
Circulation | 1997
Bo Hedén; Hans Öhlin; Ralf Rittner; Lars Edenbrandt
BACKGROUND The 12-lead ECG, together with patient history and clinical findings, remains the most important method for early diagnosis of acute myocardial infarction. Automated interpretation of ECG is widely used as decision support for less experienced physicians. Recent reports have demonstrated that artificial neural networks can be used to improve selected aspects of conventional rule-based interpretation programs. The purpose of this study was to detect acute myocardial infarction in the 12-lead ECG with artificial neural networks. METHODS AND RESULTS A total of 1120 ECGs from patients with acute myocardial infarction and 10,452 control ECGs, recorded at an emergency department with computerized ECGs, were studied. Artificial neural networks were trained to detect acute myocardial infarction by use of measurements from the 12 ST-T segments of each ECG, together with the correct diagnosis. After this training process, the performance of the neural networks was compared with that of a widely used ECG interpretation program and the classification of an experienced cardiologist. The neural networks showed higher sensitivities and discriminant power than both the interpretation program and cardiologist. The sensitivity of the neural networks was 15.5% (95% confidence interval [CI], 12.4 to 18.6) higher than that of the interpretation program compared at a specificity of 95.4% (P<.00001) and 10.5% (95% CI, 7.2 to 13.6) higher than the cardiologist at a specificity of 86.3% (P<.00001). CONCLUSIONS Artificial neural networks can be used to improve automated ECG interpretation for acute myocardial infarction. The networks may be useful as decision support even for the experienced ECG readers.
Thrombosis Research | 1987
Lars-Olof Almér; Hans Öhlin
Myocardial infarction is frequently caused by acute coronary thrombosis. A previous study in patients three years after myocardial infarction has shown twice as high concentrations of the rapid inhibitor of plasminogen activator (t-PAI) as in healthy controls. The present study involves 29 patients with acute onset of myocardial infarction. Already on admission the mean concentration of t-PAI was 16.5 +/- 7.4 units/ml as compared to 7.5 +/- 2.3 in healthy controls. It is presently unknown if moderately elevated t-PAI levels contribute to a delay of the spontaneous thrombolysis of the coronary occlusion, thus promoting the development of myocardial infarction.
Thrombosis Journal | 2005
Catharina Borna; Eduardo R. Lazarowski; Catharina van Heusden; Hans Öhlin; David Erlinge
BackgroundTo be fully activated platelets are dependent on two positive feedback loops; the formation of thromboxane A2 by cyclooxygenase in the platelets and the release of ADP. We wanted to evaluate the effect of aspirin on platelet function in patients with acute coronary syndromes and we hypothesized that increased levels of ADP in patients with acute coronary syndromes could contribute to aspirin resistance.MethodsPlatelet activity in 135 patients admitted for chest pain was assessed with PFA-100. An epinephrine-collagen cartridge (EPI-COLL) was used for the detection of aspirin resistance together with an ADP-collagen cartridge (ADP-COLL). ADP was measured with hplc from antecubital vein samples. Three subgroups were compared: chest pain with no sign of cardiac disease (NCD), NonST-elevation myocardial infarction (NSTEMI) and STEMI.ResultsPlatelet activation was increased for the STEMI group compared NCD. Aspirin resistance defined as <193 sec in EPI-COLL was 9.7 % in NCD, and increased to 26.0 % (n.s.) in NSTEMI and 83.3 % (p < 0.001) in STEMI. Chronic aspirin treatment significantly reduced platelet aggregation in NCD and NSTEMI, but it had no effect in STEMI. Plasma levels of ADP were markedly increased in STEMI (905 ± 721 nmol/l, p < 0.01), but not in NSTEMI (317 ± 245), compared to NCD (334 ± 271, mean ± SD). ADP levels correlated with increased platelet activity measured with ADP-COLL (r = -0.30, p < 0.05). Aspirin resistant patients (EPI-COLL < 193 sec) had higher ADP levels compared to aspirin responders (734 ± 807 vs. 282 ± 187 nmol/l, mean ± SD, p < 0.05).ConclusionPlatelets are activated and aspirin resistance is more frequent in STEMI, probably due to a general activation of platelets. ADP levels are increased in STEMI and correlates with platelet activation. Increased levels of ADP could be one reason for increased platelet activity and aspirin resistance.
European Journal of Clinical Investigation | 2003
Torfi Jonasson; T Hedner; Björn Hultberg; Hans Öhlin
Background Elevated plasma total homocysteine appears to be related to endothelial dysfunction and impaired nitric oxide production. We aimed to investigate [ 1 ] whether elevated levels of plasma total homocysteine are associated with high plasma levels of asymmetric dimethylarginine, an endogenous inhibitor of nitric oxide synthase, and [ 2 ] whether reduction of plasma total homocysteine levels by folate and vitamin B supplementation lowers plasma concentration of asymmetric dimethylarginine.
BMC Medical Informatics and Decision Making | 2006
Jonas Björk; Jakob Lundager Forberg; Mattias Ohlsson; Lars Edenbrandt; Hans Öhlin; Ulf Ekelund
BackgroundSeveral models for prediction of acute coronary syndrome (ACS) among chest pain patients in the emergency department (ED) have been presented, but many models predict only the likelihood of acute myocardial infarction, or include a large number of variables, which make them less than optimal for implementation at a busy ED. We report here a simple statistical model for ACS prediction that could be used in routine care at a busy ED.MethodsMultivariable analysis and logistic regression were used on data from 634 ED visits for chest pain. Only data immediately available at patient presentation were used. To make ACS prediction stable and the model useful for personnel inexperienced in electrocardiogram (ECG) reading, simple ECG data suitable for computerized reading were included.ResultsBesides ECG, eight variables were found to be important for ACS prediction, and included in the model: age, chest discomfort at presentation, symptom duration and previous hypertension, angina pectoris, AMI, congestive heart failure or PCI/CABG. At an ACS prevalence of 21% and a set sensitivity of 95%, the negative predictive value of the model was 96%.ConclusionThe present prediction model, combined with the clinical judgment of ED personnel, could be useful for the early discharge of chest pain patients in populations with a low prevalence of ACS.
Asaio Journal | 2000
Öyvind Reitan; Jan Sternby; Hans Öhlin
Cardiac intervention, myocardial infarction, or postoperative heart failure will sometimes create a need for circulatory support. For this purpose, a new, minimally invasive intra-aortic cardiac support system with a foldable propeller has been developed. In animals, the pump has been shown to have a positive hemodynamic influence, and the present study evaluates the hydraulic properties of the pump in a bench test. The axial flow pump is a catheter system with a distal motor driven foldable propeller (0-15,000 revolutions per minute). To protect the aortic wall, filaments forming a cage surround the propeller. In the present study, tests were done with two different pumps, one with and one without the cage. Two different models were used, one for testing pressure generation and one for obtaining flow-pressure characteristics. Propellers and tubes with different diameters were studied, and pressure and flow characteristics were measured. The mathematical relationships between pressure and rotational speed, pressure, and diameter of propeller and tube were determined. There was a positive relationship between the revolutions per minute and the generated pressure, a positive relationship between the diameter of the propeller and pressure, and a negative relationship between the diameter of the tube and the generated pressure. Within the physiologic range of cardiac output, there was a small drop in pressure with increasing flow in the tubes with a small diameter. With an increasing diameter of the tube, a smaller pressure drop was seen with increasing flow. The present cardiac support system has hydraulic properties, which may be of clinical relevance for patients with left ventricular heart failure.
International Journal of Cardiology | 2013
Pirkko J. Pussinen; Seppo Sarna; Mirja Puolakkainen; Hans Öhlin; Timo Sorsa; Erkki Pesonen
BACKGROUND Matrix metalloproteinase-8 (MMP-8) is involved in the breakdown of the extracellular matrix increasing the vulnerability of atherosclerotic lesions. We analysed the diagnostic value of serum MMP-8 and tissue inhibitor of metalloproteinase-1 (TIMP-1) concentrations in acute coronary syndrome (ACS) and their prognostic value in ACS recurrence. METHODS The population comprised 343 patients with ACS [including 108 unstable angina pectoris and 235 acute myocardial infarctions (AMI)] and 326 healthy controls. Additionally, 157 (45.8%) patients were resampled during the recovery. The ACS patients were followed up for 6 years. RESULTS MMP-8, TIMP-1, and their molar ratio distinguished the cases from the controls; C-statistic of the multivariate model (95% CI, p-value) including the MMP-8/TIMP-1 ratio regarding its discriminating ability for AMI was 0.922 (0.893-0.950, p<0.001). After the acute phase of ACS, median MMP-8 and TIMP-1 concentrations decreased (p<0.001) by 34.5 and 28.7%, respectively, but ended up on a different level than those found in the controls. In the follow-up, acute phase and recovery period TIMP-1 concentrations associated with cardiovascular death with hazard ratios 4.31 (2.00-9.26, p<0.001) and 4.69 (1.10-20.01, p=0.037), respectively. CONCLUSIONS The increase of serum MMP-8 and TIMP-1 concentrations may reflect plaque instability and tissue damage. TIMP-1 concentrations are associated with poor outcome in patients with ACS. The findings may have practical implications in both diagnostics and therapeutics.
Scandinavian Cardiovascular Journal | 2007
Erik Hedström; Karin Åström-Olsson; Hans Öhlin; Fredrik Frogner; Marcus Carlsson; Therese Billgren; Stefan Jovinge; Peter A. Cain; Galen S. Wagner; Håkan Arheden
Objectives. To find the time-to-peak for creatine kinase MBmass (CKMB) and cardiac troponin T (cTnT) after acute reperfusion, to compare peak and cumulative values to estimate infarct size (IS), and to evaluate clinical routine sampling for assessment of IS. Design. Acute primary percutaneous coronary intervention (PCI) was performed in 38 patients with first-time myocardial infarction. In 21 patients, CKMB and cTnT were acquired before PCI and at 1.5, 3, 6, 12, 18, 24, and 48 hours thereafter. In 17 patients, clinical routine samples were acquired at arrival, and at 10 and 20 h. IS was assessed by delayed contrast-enhanced MRI (DE-MRI). Results. Time-to-peak was 7.6±3.6 h for CKMB and 8.1±3.4 h for cTnT. Peak values correlated strongly to cumulative values (rs=0.97–0.98) as well as to DE-MRI (rs=0.8–0.82). Clinical routine sampling showed lower rs values (0.47–0.60). Conclusions. Peak values are likely captured if CKMB and cTnT are acquired at 3, 6, and 12 h after acute PCI. These peak values can be used to estimate myocardial infarct size after acute PCI.
Diabetes | 1981
Peter Jerntorp; Hans Öhlin; Bengt Bergström; Lars-Olof Almér
Chlorpropamide alcohol flushing (CPAF) in non-insulin-dependent diabetics (NIDDs) has been reported to be associated with a lower tendency to develop late complications. The flush was thought to be mediated by enkephalins and prostaglandins. Early studies could not correlate CPAF to increased levels of acetaldehyde in blood and the flush was not regarded as an antabuse-like reaction. In this study, the increase of plasma acetaldehyde during the flush in 13 CPAF positive diabetics was significantly (P < 0.005) higher than in 13 CPAF negative diabetics during a CPAF challenge test. The increase of plasma acetaldehyde was reduced to the level of CPAF negative diabetics in three CPAF positive diabetics when they were exposed to alcohol without premedication with chlorpropamide and they did not flush. The normal breakdown of ethanol to acetic acid via acetaldehyde appears to be inhibited by chlorpropamide in the flushers. Acetaldehyde measurement is an objective method to study the chlorpropamide alcohol flush and it appears superior to the measurement of skin temperature.
Clinical Chemistry and Laboratory Medicine | 2005
Torfi Jonasson; Ann-Kristin Öhlin; Anders Gottsäter; Björn Hultberg; Hans Öhlin
Abstract Background: Elevated plasma levels of total homocysteine (tHcy) are associated with an increased risk of developing occlusive vascular diseases. To better illustrate the relationship between plasma tHcy concentration, oxidative stress, and inflammation in patients with coronary artery disease (CAD), we measured plasma 8-isoprostane-prostaglandin F 2 (Iso-P), plasma malondialdehyde (MDA), and several markers of inflammation. We also aimed to demonstrate the effects of vitamin supplementation on these markers. Methods: A total of 93 patients with ischemic heart disease were investigated. Of these, 34 had plasma tHcy ≤8μmol/L, while 59 had plasma tHcy ≥15.0 μmol/L. The 59 patients were randomized to open therapy with folic acid, 5mg, pyridoxine, 40mg, and cyancobalamin, 1mg once daily for 3months (n=29) or to no vitamin treatment (n=30). Blood samples were obtained from both groups before randomization and 3months later. A sample was also obtained from the remaining 34 patients. Results: Plasma Iso-P, serum amyloid A (S-AA), and plasma intercellular adhesion molecule-1 (ICAM-1) concentrations were higher in patients with high plasma tHcy levels than in patients with low to normal tHcy levels. Plasma levels of P-, L-, E-selectins, MDA, C-reactive protein (CRP), and orosomucoid did not differ between the groups. Vitamin therapy reduced plasma tHcy from 17.4 (15.3/20.1) to 9.2 (8.3/10.3)μmol/L (25th and 75th percentiles in parentheses) (p<0.0001). Plasma levels of Iso-P remained unchanged and, of all inflammatory markers, only the S-AA concentrations were slightly reduced by the vitamin treatment, from 5.3 (2.2/7.0)ng/L at baseline to 4.6 (2.1/6.9)ng/L (p<0.05) after 3months of vitamin supplementation. Conclusion: Patients with CAD and high plasma tHcy levels had elevated plasma levels of Iso-P. The increase remained unaffected by plasma tHcy-lowering therapy, suggesting that homocysteine per se does not cause increased lipid peroxidation. Levels of plasma ICAM-1 and S-AA were increased in patients with high plasma tHcy, suggesting an association between homocysteinemia and low-grade inflammation.