| 1. |
- Pahlm, Ulrika, et al.
(författare)
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Comparison of teaching the basic electrocardiographic concept of frontal plane QRS axis using the classical versus the orderly electrocardiogram limb lead displays
- 1997
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Ingår i: American Heart Journal. - 1097-6744. ; 134:6, s. 1014-1018
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Tidskriftsartikel (refereegranskat)abstract
- This study compares the effectiveness of teaching the calculation of frontal plane QRS axis with the use of the classical versus the orderly electrocardiographic limb lead display. Eighty-three students from two environments were randomized into two groups and were taught to determine frontal plane axis with one of the methods. The accuracy and time to determine the axis were tested on 10 electrocardiograms. In the United States the group using the classical display achieved 4.2 (+/-2.7) correct answers, whereas those using the orderly method achieved 6.8 (+/-3.0) (p = 0.0006). The classical group used 9.2 (+/-2.8) minutes to complete the test, whereas the orderly group needed 7.2 (+/-2.0) minutes (p = 0.015). The results achieved in Sweden were similar. The use of the orderly electrocardiographic limb lead display results in greater diagnostic accuracy in less time than the classical display when determining the frontal plane QRS axis.
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| 2. |
- Pahlm, U S, et al.
(författare)
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The standard 11-lead ECG. Neglect of lead aVR in the classical limb lead display
- 1996
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Ingår i: Journal of Electrocardiology. - 1532-8430. ; 29 Suppl, s. 270-274
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates how the format of limb lead display influences electrocardiographic (ECG) interpretation. The positive aspect of lead aVR (included in the classical display) is directed opposite to that of the other leads. This could lead to an ECG interpreter's disregard of lead aVR, thus providing a "standard 11-lead ECG." It is hypothesized that when using the classical limb lead display, ECG interpreters often ignore lead aVR, even when considering complex ECGs. Thirty-five of the participants attending this International Society of Computerized Electrocardiology meeting were asked to interpret five complex ECGs, displayed in the classical format. Lead aVR had been replaced by lead -aVR on all of these recordings. Second, the participants were asked if they (1) used all 12 leads, (2) used lead aVR, and (3) noticed that lead aVR had been changed. The results indicate that a vast majority of interpreters (80-94%) did not detect when lead aVR had been reversed. This suggests that interpreters only use 11 of the standard leads when presented with the classical display method to evaluate clinical problems.
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| 3. |
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| 4. |
- Gustavsson, Anita, et al.
(författare)
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No serious late cardiac effects after adjuvant radiotherapy following mastectomy in premenopausal women with early breast cancer
- 1999
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Ingår i: International Journal of Radiation Oncology, Biology, Physics. - 0360-3016. ; 43:4, s. 745-754
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To assess cardiac mortality, coronary artery disease, myocardial dysfunction, and valvular heart disease in women younger than 65 years of age, at least 10 years after adjuvant radiotherapy following mastectomy in early breast cancer. METHODS AND MATERIALS: Ninety women (45-64 years old) with Stage II breast cancer without relapse, included in the South Sweden Breast Cancer Trial (premenopausal arm), with or without adjuvant postoperative radiotherapy +/- cyclophosphamide were examined with myocardial scintigraphy and echocardiography/Doppler, 10-17 years after radiotherapy. Thirty-four patients had been irradiated for left-sided tumors, 33 for right-sided tumors, and 23 patients had not been treated with radiotherapy. The radiotherapy (conventional roentgen, electron beams, and high-energy photon beams combined, in each patient) included the chest wall and the regional lymph nodes, with a specified target dose of 38-48 Gy, administered in daily fractions of 1.9-2.4 Gy, 5 days/week. RESULTS: No cardiac deaths were found among the original 275 patients randomized to adjuvant therapy. In the 90 patients examined, abnormal findings were recorded for ECG (14 patients), exercise test (5 patients), myocardial scintigraphy (6 patients), thickening of valve cusps (14 patients), and mild valvular regurgitation (20 patients). All patients had normal systolic function. Diastolic dysfunction was observed in 6 patients (abnormal relaxation in 4 patients and restrictive filling abnormality in 2 patients). Although no significant differences were found between the 3 study groups, there was a tendency to more abnormal findings after radiotherapy. CONCLUSION: Women younger than 50 years of age at the time of adjuvant radiotherapy following mastectomy in early breast cancer, had no serious cardiac sequelae 13 years (median) later, despite partly old-fashioned radiation techniques.
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| 5. |
- 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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| 6. |
- Hedén, Bo, et al.
(författare)
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Agreement between artificial neural networks and experienced electrocardiographer on electrocardiographic diagnosis of healed myocardial infarction
- 1996
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Ingår i: Journal of the American College of Cardiology. - 0735-1097. ; 28:4, s. 1012-1016
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Tidskriftsartikel (refereegranskat)abstract
- Objectives. The purpose of this study was to compare the diagnoses of healed myocardial infarction made from the 12-lead electrocardiogram (ECG) by artificial neural networks and an experienced electrocardiographer. Background. Artificial neural networks have proved of value in pattern recognition tasks. Studies of their utility in ECG interpretation have shown performance exceeding that of conventional ECG interpretation programs. The latter present verbal statements, often with an indication of the likelihood for a certain diagnosis, such as 'possible left ventricular hypertrophy'. A neural network presents its output as a numeric value between 0 and 1; however, these values can be interpreted as Bayesian probabilities. Methods. The study was based on 351 healthy volunteers and 1,313 patients with a history of chest pain who had undergone diagnostic cardiac catheterization. A 12-lead ECG was recorded in each subject. An expert electrocardiographer classified the ECGs in five different groups by estimating the probability of anterior myocardial infarction. Artificial neural networks were trained and tested to diagnose anterior myocardial infarction. The network outputs were divided into five groups by using the output values and four thresholds between 0 and 1. Results. The neural networks diagnosed healed anterior myocardial infarctions at high levels of sensitivity and specificity. The network outputs were transformed to verbal statements, and the agreement between these probability estimates and those of an expert electrocardiographer was high. Conclusions. Artificial neural networks can be of value in automated interpretation of ECGs in the near future.
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| 7. |
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| 8. |
- Lindqvist, A, et al.
(författare)
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Artery blood pressure oscillation after active standing up: an indicator of sympathetic function in diabetic patients
- 1997
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Ingår i: Clinical Physiology. - : Wiley. - 1365-2281 .- 0144-5979. ; 17:2, s. 159-169
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Tidskriftsartikel (refereegranskat)abstract
- Dynamic artery blood pressure (Finapres) response to active standing up, normally consisting of initial rise, fall and recovery above the baseline (overshoot), was compared with the early steady-state artery blood pressure level to measure sympathetic vasomotor function in healthy subjects (n = 23, age 35 +/- 9 years; mean +/-SD) and in type I diabetic patients without autonomic neuropathy (AN) (group 1: n = 18, 38 +/- 13 years), with AN but no cardiovascular drugs (group 2a: n = 7, 44 +/- 11 years) and with both AN and cardiovascular drugs (group 2b: n = 10, 47 +/- 7 years). Systolic and diastolic overshoot were similar in the control (15 +/- 13/15 +/- 11 mmHg) and group 1 subjects. Systolic overshoot disappeared in 57% of patients in group 2a (-1 +/- 9 mmHg; P < 0.03), whereas artery blood pressure still overshot in diastole (8 +/- 7 mmHg; NS). Systolic overshoot disappeared in all patients in group 2b (-22 +/- 22 mmHg; P < 0.0006) and diastolic overshoot disappeared in 60% of these patients (-6 +/- 16 mmHg; P = 0.0006). Systolic early steady-state level was not lower in group 2a than in group 1 (NS), but it was impaired in group 2b (P < 0.006), in which six diabetic patients had a pathological response beyond the age-related reference values. There was a strong association between the overshoot and steady-state levels (P for chi 2 < 0.001, n = 58). Overshoot of the control subjects and patients in group 2b correlated to their respective steady-state blood pressure levels (r > or = 0.76; P < or = 0.001). In conclusion, baroreceptor reflex-dependent overshoot of the artery blood pressure after active standing up diminishes with the development of AN and it is associated with the early steady-state level of the artery blood pressure.
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| 9. |
- Torffvit, Ole, et al.
(författare)
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The association between diabetic nephropathy and autonomic nerve function in type 1 diabetic patients
- 1997
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Ingår i: Scandinavian Journal of Clinical & Laboratory Investigation. - 1502-7686. ; 57:2, s. 183-191
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Tidskriftsartikel (refereegranskat)abstract
- Diabetic cardiovascular autonomic neuropathy increases the risk of deterioration in renal function and is associated with increased mortality in patients with renal failure. Type 1 diabetic patients with long diabetes duration, matched for age (38 +/- 9 years) and diabetes duration (28 +/- 8 years) were studied regarding the association between cardiovascular autonomic nerve function and different degrees of diabetic nephropathy. Eighteen patients were normo- (< 30 mg/l), six micro- (30-300 mg/l), and 13 macroalbuminuric (> 300 mg/l) based on urinary albumin concentrations in three separate morning samples. They were compared with 33 control subjects with similar age. Autonomic nerve function was evaluated by measuring the response of heart rate to deep breathing and active standing. Beat-to-beat finger artery blood pressure (Finapres) was tested during active standing. During deep breathing both change in heart rate (17 +/- 11, 9 +/- 7 and 4 +/- 3 beats/min) and ratio between expiratory and inspiratory R-R intervals (1.32 +/- 0.24, 1.14 +/- 0.15 and 1.05 +/- 0.04) decreased from normo- over micro- to macroalbuminuria (p < 0.05 vs normoalbuminuric and control subjects [17 +/- 5 beats/min and 1.28 +/- 0.10, respectively]). Similar results were obtained during active standing with respect to change in systolic arterial blood pressure (3 +/- 8, 2 +/- 13 and -6 +/- 11 mmHg; p < 0.05 vs control subjects [8 +/- 11 mmHg]). However, the response of diastolic arterial blood pressure or mean heart rate to standing up did not differ between any of the groups. The ratio of maximum to minimum R-R interval during the dynamic response of heart rate to active standing decreased with the degree of nephropathy (1.27 +/- 0.17, 1.11 +/- 0.11 and 1.05 +/- 0.06) with significantly higher values in patients with normo- compared with patients with macroalbuminuria (p < 0.05). All patients groups had significantly lower values than control subjects (1.46 +/- 0.22, p < 0.05). The overshoot of the blood pressure after an initial fall during active standing decreased with the degree of diabetic nephropathy. In conclusion, type 1 diabetic patients with long duration of diabetes have signs of cardiovascular autonomic neuropathy, the severity of which is related to the degree of nephropathy.
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