| 1. |
- Hede ́n, Bo, et al.
(författare)
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Artificial neural networks for recognition of electrocardiographic lead reversal
- 1995
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Ingår i: American Journal of Cardiology. - 0002-9149. ; 75:14, s. 929-933
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Tidskriftsartikel (refereegranskat)abstract
- Misplacement of electrodes during the recording of an electrocardiogram (ECG) can cause an incorrect interpretation, misdiagnosis, and subsequent lack of proper treatment. The purpose of this study was twofold: (1) to develop artificial neural networks that yield peak sensitivity for the recognition of right/left arm lead reversal at a very high specificity; and (2) to compare the performances of the networks with those of 2 widely used rule-based interpretation programs. The study was based on 11,009 ECGs recorded in patients at an emergency department using computerized electrocardiographs. Each of the ECGs was used to computationally generate an ECG with right/left arm lead reversal. Neural networks were trained to detect ECGs with right/left arm lead reversal. Different networks and rule-based criteria were used depending on the presence or absence of P waves. The networks and the criteria all showed a very high specificity (99.87% to 100%). The neural networks performed better than the rule-based criteria, both when P waves were present (sensitivity 99.1%) or absent (sensitivity 94.5%). The corresponding sensitivities for the best criteria were 93.9% and 39.3%, respectively. An estimated 300 million ECGs are recorded annually in the world. The majority of these recordings are performed using computerized electrocardiographs, which include algorithms for detection of right/left arm lead reversals. In this study, neural networks performed better than conventional algorithms and the differences in sensitivity could result in 100,000 to 400,000 right/left arm lead reversals being detected by networks but not by conventional interpretation programs.
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| 2. |
- Ohlsson, Mattias, et al.
(författare)
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Usefulness of serial electrocardiograms for diagnosis of acute myocardial infarction
- 2001
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Ingår i: American Journal of Cardiology. - 0002-9149. ; 88:5, s. 478-481
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to determine whether the automated detection of acute myocardial infarction (AMI) by utilizing artificial neural networks was improved by using a previous electrocardiogram (ECG) in addition to the current ECG. A total of 4,691 ECGs were recorded from patients admitted to an emergency department due to suspected AMI. Of these, 902 ECGs, in which diagnoses of AMI were later confirmed, formed the study group, whereas the remaining 3,789 ECGS comprised the control group. For each ECG recorded, a previous ECG of the same patient was selected from the clinical electrocardiographic database. Artificial neural networks were then programed to detect AMI based on either the current ECG only or on the combination of the previous and the current ECGs. On this basis, 3 assessors - a neural network, an experienced cardiologist, and an intern - separately classified the ECGs of the test group, with and without access to the previous ECG. The detection performance, as measured by the area under the receiver operating characteristic curve, showed an increase for all assessors with access to previous ECGs. The neural network improved from 0.85 to 0.88 (p = 0.02), the cardiologist from 0.79 to 0.81 (p = 0.36), and the intern from 0.71 to 0.78 (p <0.001). Thus, the performance of a neural network, detecting AMI in an ECG, is improved when a previous ECG is used as an additional input.
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| 4. |
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| 5. |
- Al-Khalili, F, et al.
(författare)
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Prognostic value of exercise testing in women after acute coronary syndromes (The Stockholm Female Coronary Risk Study)
- 2000
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Ingår i: American Journal of Cardiology. - Karolinska Hosp, Dept Cardiol, S-17176 Stockholm, Sweden. Karolinska Hosp, Dept Publ Hlth Sci, Div Prevent Med, S-17176 Stockholm, Sweden. Karolinska Inst, Stockholm, Sweden. : EXCERPTA MEDICA INC-ELSEVIER SCIENCE INC. - 0002-9149 .- 1879-1913. ; 86:2, s. 211-213
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Tidskriftsartikel (refereegranskat)
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| 6. |
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| 8. |
- Albertsson, Per, 1956, et al.
(författare)
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Morbidity and use of medical resources in patients with chest pain and normal or near-normal coronary arteries.
- 1997
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Ingår i: The American journal of cardiology. - : Excerpta Medica, Inc.. - 0002-9149 .- 1879-1913. ; 79:3, s. 299-304
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Tidskriftsartikel (refereegranskat)abstract
- To evaluate morbidity and use of medical resources in patients with chest pain and normal or near-normal coronary angiograms: 2,639 consecutive patients who underwent coronary angiograms due to chest pain were registered. Two years thereafter all patients who showed normal or near-normal coronary angiograms were approached with a questionnaire regarding hospitalization during the last 4 years (2 years before and 2 years after angiography). All medical files were also examined. Of the patients who underwent angiography, 163 (6%) had no significant stenoses, and of these, 113 showed complete normal angiograms and 50 showed mild (i.e. <50%) stenoses. During the 2 years before diagnostic angiogram, 66% of the patients were hospitalized compared with only 35% during 2 years after angiography (p <0.001). The reduction in hospitalization was due to curtailed utilization of medical resources for cardiac reasons; mean days in hospital was 6.6 days before angiography versus 2.8 days after (p <0.001). There were no significant differences in hospitalization when comparing patients with mild stenoses and completely normal angiograms. There were, furthermore, no differences between patients with positive or negative exercise tests. Thus, the need for hospitalization is significantly reduced after a diagnostic angiogram reveals normal or near-normal coronary arteries.
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| 10. |
- Andrén, Lennart, 1946, et al.
(författare)
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Diltiazem in hypertensive patients with type II diabetes mellitus.
- 1988
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Ingår i: The American journal of cardiology. - : Elsevier BV. - 0002-9149. ; 62:11
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Tidskriftsartikel (refereegranskat)abstract
- Twenty-three patients with essential hypertension and diabetes mellitus type II were treated with the calcium antagonist diltiazem (120 to 180 mg twice daily). The mean dose was 307 mg/day. The study was a double-blind, placebo-controlled, crossover design. All measurements were performed 12 to 14 hours after drug intake. Blood pressure, heart rate and forearm blood flow were measured noninvasively. Platelet function was studied by measuring adenosine diphosphate-induced platelet aggregation and the platelet specific proteins, beta thromboglobulin and platelet factor 4. Thromboxane B2 formation in serum and the plasma concentration of diltiazem and its metabolites N-demethyldiltiazem, deacetyldiltiazem and N-demethyldeacetyldiltiazem were measured both during placebo and diltiazem treatment. Diabetic control was evaluated by following HbA1C, fasting blood glucose and urinary glucose. Diltiazem reduced both systolic and diastolic (supine and standing) blood pressure significantly. Forearm blood flow was significantly increased by 32%, p less than 0.05. Supine heart rate decreased significantly, while no such change was seen in the standing position. No significant changes were observed in platelet function during diltiazem treatment. There was no relation between the observed blood pressure reduction and the plasma concentration of diltiazem or its metabolites. A positive correlation between the change in heart rate and the metabolite N-demethyldeacetyldiltiazem was observed (r = 0.647, p = 0.005). Three patients were excluded during diltiazem treatment (skin exanthema, headache and atrial fibrillation) and 1 during placebo treatment (angina pectoris). No negative effect on diabetes control was observed. Thus, diltiazem could be used for treatment of hypertension in diabetic patients.
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