Medical applications are becoming increasingly available on portable devices such as smart phones... more Medical applications are becoming increasingly available on portable devices such as smart phones, tablets and small notebooks in healthcare organizations. However, application development for diagnostic and monitoring purposes on these devices is still limited, because of regulatory requirements and significant development time and complexity for the multiple mobile platforms in use. Our objective was to create a cross-platform patient monitor solution, with the main focus on tablets and test the feasibility of this platform for patient monitoring. We have developed an HTML5-based portable patient monitoring application to be a cross-platform based solution for a broad range of tablets. The application shows the vital signs, curves and trend parameters as a monitor would display. The usability of the portable patient monitoring application has been evaluated on the iPad 3, Samsung Tab 2 10.1 and the Windows 8 platform. We tested the main browser on each platform and also the latest...
Patient monitoring with 12-lead ECG subsets typically uses the independent frontal leads I and II... more Patient monitoring with 12-lead ECG subsets typically uses the independent frontal leads I and II and any number of the six precordial leads to reconstruct the unrecorded ECG leads. However, variations of QRS amplitudes in leads I or II may have an effect on the signal to noise ratio of the reconstructed leads. The aim of this study was to develop and evaluate a dynamic frontal lead selection method (DFLS) to improve ECG reconstruction. We compared the DFLS method for general (GEN) and patient-specific (PS) reconstruction with a lead subset I, II, V 2 , and V 5 . For GEN reconstruction, a data set of 2372 diagnostic 12-lead ECGs obtained from subjects with chest pain suggestive of acute myocardial infarction was used. For PS, a data set of 71 continuous 12-lead PCI recordings was used. Reconstruction accuracy was assessed with correlation coefficients and root mean square errors. This study showed that the DFLS method increases GEN reconstruction performance in a subgroup with low QRS voltages. PS reconstruction shows a moderate overall performance increase.
Background: Electrocardiogram variations (ECG) due to body position changes and electrode placeme... more Background: Electrocardiogram variations (ECG) due to body position changes and electrode placements are common problems of continuous ST-T monitoring. Body position changes may cause QRS and ST-T changes and trigger false alarms. Placement of arm and leg electrodes in a coronary care unit environment is usually near the thorax instead of standard position at the wrists and ankles. This may affect the limb leads and complicate diagnostic interpretation. The purpose of this study was to assess the effects of these sources of ECG variation and to correct for them. Continuous 12-lead ECG recordings were obtained from 160 patients admitted to the coronary care unit. Each patient underwent a body position test (supine, left-lateral, and upright position). Scalar and spatial approaches were investigated for reconstruction of the ECG in supine position. The scalar approach uses linear regression. The spatial approach transforms the ECG into a derived vestorcardiogram. The spatial QRS-loop is then rotated and scaled to match the vector loop in supine position and transformed back to a 12-lead ECG. Materials and Methods: To assess the effect of electrode placement, monitoring and standard limb leads were simultaneously recorded in a group of 80 patients. To map the monitoring leads to standard leads, general and patient-specific reconstruction coefficients were derived by linear regression from half of the patients and tested on the other half. Similarity between the reference and reconstructed ECGs was measured by correlation, similarity coefficient [(SCϭ1-RMS(residual error)/ RMS(signal)], and difference in frontal QRS-Axis. Results and Conclusion: Only 14% (23 of 160) of the patients showed marked ECG changes (ST elevations, QRS-axis shifts, T-wave inversions). The scalar method (median correlation Ͼ 0.994, SC Ͼ 0.902, QRS axis difference 0 degrees) performed better than spatial (median correlation 0.946, SC Ͼ 0.792, QRS axis difference 0 degrees). Monitoring leads can be mapped to standard limb leads in good to excellent approximaiton. General reconstruction (median correlation 0.993 and SC 0.764) performed slightly worse than patient-specific reconstruction (median correlation 0.997 and SC 0.908).
In recent years, several derived 12-lead electrocardiogram (ECG) systems have been developed but ... more In recent years, several derived 12-lead electrocardiogram (ECG) systems have been developed but have never been directly compared for accuracy. The aim of the study was to test simultaneous EASI (1) and two other derived ECG methods against standard ECG at rest and during ischemia.
Aim: The aim of the study was to simultaneously test the EASI lead system and two other derived E... more Aim: The aim of the study was to simultaneously test the EASI lead system and two other derived ECG methods against the standard 12-lead ECG during percutaneous coronary intervention (PCI). Methods: During 44 percutaneous coronary interventions, a simultaneously recorded 12-lead and EASI ECG were marked at the start of the PCI (baseline) and at known ischemia caused by balloon inflation (peak). ST deviations were measured 60 ms after the J point at baseline and peak in all leads and were summated (SUMST) to assess overall changes. For regional changes, the lead with the highest ST deviation (PEAKST) was marked. For each patient, derived 12-lead ECGs were computed from the EASI leads and a lead subset using patient-specific coefficients (PS) and coefficients based on a patient population (GEN). Absolute differences were computed between each derived and routine ECG for SUMST and PEAKST. Results: SUMST was at baseline 567 μV (range: 150-1707) and increased at peak to 871 μV (range: 350-2101). SUMST difference at peak was for EASI: 163 μV (CI: 90-236, P b.001), GEN: 46 μV (CI: 2-91, P = .40), and PS: 16 μV (CI: 3-30, P = .15). PEAKST difference at peak was for EASI: 49 μV (CI: 19-220, P = .02), GEN: 48 μV (CI: -43-154, P = .26), and PS: 20 μV (CI: -51-32, P = .65). Conclusion: Simultaneous direct comparison of three derived ECG methods shows overall and regional differences in accuracy across PS, GEN, and EASI. Median SUMST and PEAKST differences for PS are lower than for GEN and EASI, and show a more accurate reconstruction.
Twelve-lead ST-segment monitoring is a widely used tool for capturing focal ischemia and transien... more Twelve-lead ST-segment monitoring is a widely used tool for capturing focal ischemia and transient intermittent episodes. However, continuous registration of all 10 electrodes is impractical in clinical settings. This study investigated the accuracy of 2 derived 12-lead strategies that required 6 electrodes, including all limb leads, and 2 precordial leads by using population-based (generalized) and individualized (patient-specific) reconstruction coefficients to derive the additional 4 chest leads. A total of 26,880 simultaneous digital conventional 12-lead generalized and patient-specific electrocardiograms were monitored over 112 hours in 39 patients during percutaneous coronary intervention, including 159 balloon occlusions in 63 arteries, to test accuracy at rest and during ischemia. Occlusion duration was 78 seconds (range 42 to 96) in the left main coronary in 2 patients, the left anterior descending artery in 15, the right coronary artery in 10, the circumflex artery in 2, and graft segments in 5 patients. Average summated 12-lead ST deviation over the study population at base-line was 377 V (range 104 to 1,718), which increased at peak ischemia to an average of 1,086 V (range 282 to 4,099). Median absolute differences at peak ischemic ST deviation were 25 V in lead V 1 , 0 V in lead V 2 , 35 V in lead V 3 , 34 V in lead V 4 , 0 V in lead V 5 , 11 V in lead V 6 , and 114 V for summated 12-lead ST deviation with the generalized method and 7 V in lead V 1 , 4 V in lead V 2 , 1 V in lead V 3 , 5V in lead V 4 , 4 V in lead V 5 , 9 V in lead V 6 , and 83 V for the summated 12-lead ST deviation with the patient-specific method. Limb leads (I, II, III, aVR, aVL, and aVF) were identical in all patients. Thus, generalized and patient-specific methods derived from 12-lead electrocardiography using actual limb and 2 precordial electrodes accurately derived the additional chest leads at rest and during ischemia. These approaches appear to be more practical than conventional 10-electrode monitoring but preserve high accuracy. ᮊ2004
Medical applications are becoming increasingly available on portable devices such as smart phones... more Medical applications are becoming increasingly available on portable devices such as smart phones, tablets and small notebooks in healthcare organizations. However, application development for diagnostic and monitoring purposes on these devices is still limited, because of regulatory requirements and significant development time and complexity for the multiple mobile platforms in use. Our objective was to create a cross-platform patient monitor solution, with the main focus on tablets and test the feasibility of this platform for patient monitoring. We have developed an HTML5-based portable patient monitoring application to be a cross-platform based solution for a broad range of tablets. The application shows the vital signs, curves and trend parameters as a monitor would display. The usability of the portable patient monitoring application has been evaluated on the iPad 3, Samsung Tab 2 10.1 and the Windows 8 platform. We tested the main browser on each platform and also the latest...
Patient monitoring with 12-lead ECG subsets typically uses the independent frontal leads I and II... more Patient monitoring with 12-lead ECG subsets typically uses the independent frontal leads I and II and any number of the six precordial leads to reconstruct the unrecorded ECG leads. However, variations of QRS amplitudes in leads I or II may have an effect on the signal to noise ratio of the reconstructed leads. The aim of this study was to develop and evaluate a dynamic frontal lead selection method (DFLS) to improve ECG reconstruction. We compared the DFLS method for general (GEN) and patient-specific (PS) reconstruction with a lead subset I, II, V 2 , and V 5 . For GEN reconstruction, a data set of 2372 diagnostic 12-lead ECGs obtained from subjects with chest pain suggestive of acute myocardial infarction was used. For PS, a data set of 71 continuous 12-lead PCI recordings was used. Reconstruction accuracy was assessed with correlation coefficients and root mean square errors. This study showed that the DFLS method increases GEN reconstruction performance in a subgroup with low QRS voltages. PS reconstruction shows a moderate overall performance increase.
Background: Electrocardiogram variations (ECG) due to body position changes and electrode placeme... more Background: Electrocardiogram variations (ECG) due to body position changes and electrode placements are common problems of continuous ST-T monitoring. Body position changes may cause QRS and ST-T changes and trigger false alarms. Placement of arm and leg electrodes in a coronary care unit environment is usually near the thorax instead of standard position at the wrists and ankles. This may affect the limb leads and complicate diagnostic interpretation. The purpose of this study was to assess the effects of these sources of ECG variation and to correct for them. Continuous 12-lead ECG recordings were obtained from 160 patients admitted to the coronary care unit. Each patient underwent a body position test (supine, left-lateral, and upright position). Scalar and spatial approaches were investigated for reconstruction of the ECG in supine position. The scalar approach uses linear regression. The spatial approach transforms the ECG into a derived vestorcardiogram. The spatial QRS-loop is then rotated and scaled to match the vector loop in supine position and transformed back to a 12-lead ECG. Materials and Methods: To assess the effect of electrode placement, monitoring and standard limb leads were simultaneously recorded in a group of 80 patients. To map the monitoring leads to standard leads, general and patient-specific reconstruction coefficients were derived by linear regression from half of the patients and tested on the other half. Similarity between the reference and reconstructed ECGs was measured by correlation, similarity coefficient [(SCϭ1-RMS(residual error)/ RMS(signal)], and difference in frontal QRS-Axis. Results and Conclusion: Only 14% (23 of 160) of the patients showed marked ECG changes (ST elevations, QRS-axis shifts, T-wave inversions). The scalar method (median correlation Ͼ 0.994, SC Ͼ 0.902, QRS axis difference 0 degrees) performed better than spatial (median correlation 0.946, SC Ͼ 0.792, QRS axis difference 0 degrees). Monitoring leads can be mapped to standard limb leads in good to excellent approximaiton. General reconstruction (median correlation 0.993 and SC 0.764) performed slightly worse than patient-specific reconstruction (median correlation 0.997 and SC 0.908).
In recent years, several derived 12-lead electrocardiogram (ECG) systems have been developed but ... more In recent years, several derived 12-lead electrocardiogram (ECG) systems have been developed but have never been directly compared for accuracy. The aim of the study was to test simultaneous EASI (1) and two other derived ECG methods against standard ECG at rest and during ischemia.
Aim: The aim of the study was to simultaneously test the EASI lead system and two other derived E... more Aim: The aim of the study was to simultaneously test the EASI lead system and two other derived ECG methods against the standard 12-lead ECG during percutaneous coronary intervention (PCI). Methods: During 44 percutaneous coronary interventions, a simultaneously recorded 12-lead and EASI ECG were marked at the start of the PCI (baseline) and at known ischemia caused by balloon inflation (peak). ST deviations were measured 60 ms after the J point at baseline and peak in all leads and were summated (SUMST) to assess overall changes. For regional changes, the lead with the highest ST deviation (PEAKST) was marked. For each patient, derived 12-lead ECGs were computed from the EASI leads and a lead subset using patient-specific coefficients (PS) and coefficients based on a patient population (GEN). Absolute differences were computed between each derived and routine ECG for SUMST and PEAKST. Results: SUMST was at baseline 567 μV (range: 150-1707) and increased at peak to 871 μV (range: 350-2101). SUMST difference at peak was for EASI: 163 μV (CI: 90-236, P b.001), GEN: 46 μV (CI: 2-91, P = .40), and PS: 16 μV (CI: 3-30, P = .15). PEAKST difference at peak was for EASI: 49 μV (CI: 19-220, P = .02), GEN: 48 μV (CI: -43-154, P = .26), and PS: 20 μV (CI: -51-32, P = .65). Conclusion: Simultaneous direct comparison of three derived ECG methods shows overall and regional differences in accuracy across PS, GEN, and EASI. Median SUMST and PEAKST differences for PS are lower than for GEN and EASI, and show a more accurate reconstruction.
Twelve-lead ST-segment monitoring is a widely used tool for capturing focal ischemia and transien... more Twelve-lead ST-segment monitoring is a widely used tool for capturing focal ischemia and transient intermittent episodes. However, continuous registration of all 10 electrodes is impractical in clinical settings. This study investigated the accuracy of 2 derived 12-lead strategies that required 6 electrodes, including all limb leads, and 2 precordial leads by using population-based (generalized) and individualized (patient-specific) reconstruction coefficients to derive the additional 4 chest leads. A total of 26,880 simultaneous digital conventional 12-lead generalized and patient-specific electrocardiograms were monitored over 112 hours in 39 patients during percutaneous coronary intervention, including 159 balloon occlusions in 63 arteries, to test accuracy at rest and during ischemia. Occlusion duration was 78 seconds (range 42 to 96) in the left main coronary in 2 patients, the left anterior descending artery in 15, the right coronary artery in 10, the circumflex artery in 2, and graft segments in 5 patients. Average summated 12-lead ST deviation over the study population at base-line was 377 V (range 104 to 1,718), which increased at peak ischemia to an average of 1,086 V (range 282 to 4,099). Median absolute differences at peak ischemic ST deviation were 25 V in lead V 1 , 0 V in lead V 2 , 35 V in lead V 3 , 34 V in lead V 4 , 0 V in lead V 5 , 11 V in lead V 6 , and 114 V for summated 12-lead ST deviation with the generalized method and 7 V in lead V 1 , 4 V in lead V 2 , 1 V in lead V 3 , 5V in lead V 4 , 4 V in lead V 5 , 9 V in lead V 6 , and 83 V for the summated 12-lead ST deviation with the patient-specific method. Limb leads (I, II, III, aVR, aVL, and aVF) were identical in all patients. Thus, generalized and patient-specific methods derived from 12-lead electrocardiography using actual limb and 2 precordial electrodes accurately derived the additional chest leads at rest and during ischemia. These approaches appear to be more practical than conventional 10-electrode monitoring but preserve high accuracy. ᮊ2004
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Papers by Teus Van Dam