| 1. |
- Ericsson, Anders B., et al.
(författare)
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Correlation between a Mid-ventricular Volume Segment and Global Left Ventricular Volume Measured by the Conductance Catheter
- 2001
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Ingår i: Scandinavian Cardiovascular Journal. - : Informa UK Limited. - 1401-7431 .- 1651-2006. ; 35:2, s. 129-135
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Tidskriftsartikel (refereegranskat)abstract
- Objectives-To investigate whether acute volume changes in single volume segments of the left ventricle can be correlated with global volume changes. If so, changes in global volume might be predicted from changes in segmental volumes. Design-Volume changes were recorded in six pigs in five intraventricular segments, from apex to heart base, using the conductance catheter (at baseline, after 60 min of apical ischaemia, during preload reduction and afterload increase). A computer algorithm was created to calculate the instantaneous absolute difference between the curve shape of global and normalized segmental volume as a percentage of global stroke volume. Results-For a mid-cardiac volume segment constituting 34 (14-39)% [median (range)] of global stroke volume, the mean difference over a cardiac cycle was 4 (1-8)% at baseline. Apical ischaemia resulted in apical dyskinesia, but did not influence the mid-cardiac segment. Conclusions-The volume curve from a segment at mid-cardiac level seems to be a good estimator of the global volume curve, thus giving a foundation for estimation of global volume changes from such a segment.
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| 2. |
- Kronander, Håkan, et al.
(författare)
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Analysis of ST/HR hysteresis improves long-term prognostic value of exercise ECG test.
- 2011
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Ingår i: International Journal of Cardiology. - : Elsevier BV. - 0167-5273 .- 1874-1754. ; 148:1, s. 64-9
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: ST/HR hysteresis is one of the better diagnostic exercise ECG variables for coronary artery disease. This study evaluates the long-term prognostic value of ST/HR hysteresis in predicting acute myocardial infarction (AMI) and all-cause mortality in men and women. METHODS: The study population consisted of 8317 patients who had undergone routine exercise test on bicycle ergometer at one Swedish centre. Information on AMI and all-cause mortality was obtained from national Swedish registers covering a mean follow-up period of 9.5 years. RESULTS: The adjusted hazard ratio for AMI at a diagnostic cut point of ≤-20 µV for ST/HR hysteresis was 1.88 (95% CI, 1.62-2.17) in men and 2.31 (95% CI, 1.83-2.91) in women. For all-cause death the adjusted hazard ratio was 1.72 (95% CI, 1.52-1.96) in men and 1.90 (95% CI, 1.57-2.29) in women. The corresponding hazard ratios for ST-segment depression with horizontal or down-sloping ST-segment, ST-segment depression, ST/HR index, and ST/HR slope were lower. For comparison, the adjusted hazard ratio for AMI using maximal workload in percent of predicted was 2.02 (95% CI, 1.77-2.32) in men and 2.14 (95% CI, 1.71-2.67) in women. Area under the ROC curves for prediction of AMI was significantly larger using ST/HR hysteresis than using any of three other evaluated ECG indicators. CONCLUSIONS: ST/HR hysteresis appears to improve the prognostic ability of an exercise ECG test for AMI and all-cause mortality in a long-term perspective compared to conventional ST-segment and ST/HR indicators in both genders and clearly more markedly in women.
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| 3. |
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| 4. |
- Kronander, Håkan, 1953-
(författare)
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Diagnostic and Prognostic Value of Exercise Electrocardiographic Test Variables in Coronary Artery Disease
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The diagnostic performance of conventional analysis of the exercise electrocardiographic (ECG) test for the detection of coronary artery disease (CAD) is limited to 70-75%. The exercise ECG test is the most widely used non-invasive method for assessing CAD and even a small improvement in the diagnostic performance is important. The objective of this thesis was to investigate the diagnostic performance of the exercise ECG test for diagnosis of CAD and the prognostic performance of the test for predicting acute myocardial infarction (AMI), in both men and women. In the diagnostic part of the present study, aimed at finding the optimal diagnostic information during the exercise and recovery phase, 1,877 electrocardiograms selected from 8,322 consecutive patients undergoing a routine exercise test on bicycle ergometer were evaluated. CAD was verified angiographically in 669 patients and excluded in 1,208 patients, by angiography (119 patients), by myocardial scintigraphy (250 patients), or on clinical grounds (839 patients). The diagnostic performance of ST-segment amplitude, and the difference between heart rate (HR) matched recovery and exercise ST-segment amplitudes (ST/HR difference), were evaluated by constructing receiver operating characteristic (ROC) curves for each sample point every 12th second during 10 minutes of recovery as well as the last 4 minutes of exercise for the ST-segment amplitude. ST-segment amplitude performed better after exercise than during exercise and best within the first 2 minutes of recovery. Its diagnostic ability did not differ from the ST/HR difference. Both methods performed better in men than in women and the diagnostic information appeared mainly in leads I, -aVR, II, V4, V5 and V6. The effect of different sampling rates (1, 2 and 5 samples/min) on the CAD discrimination ability of ST/HR loop area was evaluated by using ROC curves. A use of sampling frequency below 2 samples/min resulted in a significantly diminished diagnostic performance. ST-segment and ST/HR variables were compared during exercise and during early post-exercise recovery in terms of diagnostic discrimination capacity and optimal partition values. Discriminating capacity of the methods was evaluated by the use of ROC areas. Partition values, providing the combination of the best sensitivity and specificity, were established. The results demonstrate that analysis of post-exercise ST/HR hysteresis offers the most accurate and gender indifferent identification of patients with CAD. The prognostic part of the study included 8,317 of the 8,322 patients and covered a mean follow-up period of 9.5 years. This part of the study was used to evaluate the long-term prognostic value of ST/HR hysteresis in predicting AMI and all-cause mortality in men and women. ST/HR hysteresis appears to improve the prognostic ability of an exercise ECG test for AMI and all-cause mortality in a long term perspective compared to conventional ST-segment and ST/HR indicators in both genders and clearly more markedly in women.
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| 5. |
- Kronander, Håkan, et al.
(författare)
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Diagnostic performance and partition values of exercise electrocardiographic variables in the detection of coronary artery disease - improved accuracy by using ST/HR hysteresis
- 2010
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Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 30:2, s. 98-106
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Tidskriftsartikel (refereegranskat)abstract
- P>Exercise electrocardiography is widely used for initial identification of patients with coronary artery disease (CAD). This study compares the measurements of ST-segment changes during exercise and during early postexercise recovery in terms of diagnostic discrimination capacity and optimal partition values. Data from 1876 patients undergoing a routine bicycle exercise test were analysed. CAD was angiographically verified in 668 patients, and excluded by angiography (n = 119), myocardial scintigraphy (n = 250), and on clinical grounds (n = 839) in 1208 patients. Postexercise ST/HR hysteresis was calculated as normalized for heart rate (HR) ST/HR loop area during the first 3 min of recovery. ST/HR index was obtained by dividing the overall ST amplitude change during exercise by exercise-induced HR change, and ST/HR slope was calculated using linear regression analysis of ST/HR data pairs during exercise. ST-segment depression was measured during, and for 3 min after the exercise. Discriminating capacity of the methods was evaluated in terms of receiver operating characteristic areas and optimal partition values providing the combination of the best sensitivity and specificity were established. The best diagnostic discrimination was provided by ST/HR hysteresis at optimal partition value of -15 mu V, followed by postexercise ST amplitude measurements at gender-specific partition values of -10 to -90 mu V, ST/HR slope [partition value 2 center dot 4 mu V (beats/min)-1], ST/HR index [partition value 1 center dot 6 mu V (beats/min)-1], and ST-segment depression during exercise (partition value 70 mu V in men and 90 mu V in women). The results demonstrate that analysis of postexercise ST/HR hysteresis offers the most accurate and gender indifferent identification of patients with CAD.
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| 6. |
- Kronander, Håkan, et al.
(författare)
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Exercise electrocardiography for diagnosis of coronary artery disease: impact of sampling rate on the diagnostic performance of ST/HR-loop based on data from early recovery phase
- 2007
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Ingår i: Clinical Physiology and Functionel Imaging. - 1475-0961. ; 28:2, s. 96-100
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Tidskriftsartikel (refereegranskat)abstract
- Quantitative analysis of electrocardiographic ST-segment/heart rate relationship (ST/HR loop) during early recovery phase of exercise stress test provides a sensitive tool for the detection of coronary artery disease (CAD). This study evaluates the effect of data sampling frequency on the diagnostic performance of ST/HR loop in 1876 patients undergoing a routine exercise test on a bicycle ergometer. CAD was verified angiographically in 668 patients and excluded by coronary angiography (n = 119), myocardial scintigraphy (n = 250) and on clinical grounds (n = 839) in 1208 patients. The normalized ST/HR loop area was calculated in all cases by integration of ST-segment amplitude difference from the end of exercise to the end of the first 3 min of recovery period over HR and dividing the integral by the HR difference over the integration period. The effect of different sampling rates (one, two and five samples per minute) on the CAD discrimination ability of ST/HR loop area was subsequently evaluated using receiver operating characteristic (ROC) curves. Reduction in ST/HR data sampling frequency from two to one sample per minute resulted in a significantly decreased diagnostic performance of the ST/HR loop whereas no differences in CAD discrimination capacity were observed between sampling frequencies of two and five samples per minute. The choice of ST/HR data sampling frequency may have a significant impact on the CAD diagnostic ability of the ST/HR loop. The use of sampling frequency below two samples per minute results in a significantly diminished diagnostic performance, a fact that should be taken into consideration when employing ST/HR diagnostic procedures.
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| 7. |
- Kronander, Håkan, et al.
(författare)
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Improved capacity of exercise electrocardiography in the detection of coronary artery disease by focusing on diagnostic variables during the early recovery phase
- 2005
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Ingår i: Journal of Electrocardiology. - : Elsevier BV. - 0022-0736 .- 1532-8430. ; 38:2, s. 130-138
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Tidskriftsartikel (refereegranskat)abstract
- The temporal distribution of the diagnostic information for the detection of coronary artery disease (CAD) provided by exercise-induced electrocardiographic (ECG) ST-segment amplitude changes in different ECG leads in men and women has not been fully investigated. To shed further light in this area, 1877 electrocardiograms selected from 8322 patients undergoing a routine exercise test on a bicycle ergometer were evaluated. ST-segment amplitude and the difference between heart rate-matched recovery and exercise ST-segment amplitudes (ST/HR difference) were measured. Coronary artery disease was verified angiographically in 669 patients and excluded in 1208 patients by angiography (n = 119), by myocardial scintigraphy (n = 250), or on clinical grounds (n = 839). The diagnostic performance of the 2 ECG methods used was assessed by constructing receiver operating characteristic curves for each sampling point every 12 seconds during 10 minutes of recovery as well as the last 4 minutes of exercise for the ST-segment amplitude. ST-segment amplitude performed better after exercise than during exercise and best within the first 2 minutes of recovery. Its diagnostic ability did not differ from the ST-amplitude hysteresis assessed by the difference between recovery ST-segment amplitude and exercise ST-segment amplitude at matched heart rate. Both methods performed better in men and the diagnostic information appeared mainly in leads I, -aVR, II, V-4, V-5, and V-6. The best discrimination of CAD is provided by analysis of ST-segment amplitude changes in 6 specific leads early during the recovery phase. This information should be targeted by exercise ECG diagnostic methods.
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| 8. |
- Söderqvist, Emil, et al.
(författare)
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Design of a single segment conductance catheter for measurement of left ventricular volume
- 2001
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Ingår i: Annual Reports of the Research Reactor Institute, Kyoto University. ; , s. 151-154
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Konferensbidrag (refereegranskat)abstract
- The objective of this paper is to investigate how to best position the sensing electrodes on a single segment conductance catheter, and to calculate the expected performance. Using electrode potential data, obtained with the present five segment conductance catheter in pig experiments, we have interpolated the electrical field at any given point of time, and calculated what volume curve to expect with only two sensing electrodes. Comparison shows that the deviation between our calculated method and the present one is stable and small. Mean deviation with optimized electrode positions was 0.05% per sample, and the maximum deviation found for a single time sample was 2.57%. This indicates that it is possible to build a thin single segment catheter with as good performance as for the present five segment conductance catheter.
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