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Assessing perception of new methods that represent ST deviation
698
Poster Session 2 / Journal of Electrocardiology 45 (2012) 697–701
New 3D patient-specific morphing tool translates ECG/VCG waveforms into cardiac MRI and CT anatomy Peter Michael van Dam a, Michael Laks b, a Peacs, Arnhem, the Netherlands b David Geffen School of Medicine at UCLA, Los Angeles, USA Patient-specific heart and thorax models derived from MRI/CT images would increase the accuracy of the translationed ECG and VCG waveforms. Moreover, such models would also enable the quantitative analysis of the heart and thus support the diagnosis and treatment of the patient, e.g., identification of ischemic zones or ablation sites. Currently no computer tools are available to create these patient-specific heart and thorax models. Therefore we developed (semi)automatic morphing software that reconstructs the patient-specific heart and thorax geometry from MRI/CT. We created a new mathematical morphing approach to translate all the significant anatomical structures of the heart and thorax into mathematical algorithms. We used this approach because standard morphing techniques do not correctly model many of the heart structures, for example, the right ventricular septum connects at an acute angle. By using the reference point of the RVOT and the apex of the right ventricle, the acute angle of the right ventricle was located and thereby could be appropriately mathematical modeled. This technique was used to morph the whole heart, lung, liver, and thorax model. Ten adult patient-specific models have been reconstructed from MRI and CT (5 male, 5 female, 2 normal and 8 arrhythmia patients). On average only 12– 20 short-axis and 2–4 long-axis images were needed to make an accurate reconstruction. For the 10 reconstructed ventricles the mean deviation between MRI/CT contours and ventricular models were less 1.1 ± 0.9 mm. For the thorax and lungs the deviation was than 2.0 ± 1.5 mm. This novel 3D patient-specific morphing tool enables a new field of research and teaching creating an interactive relation between cardiac MRI and CT anatomy and ECG/VCG waveforms that translates them to localize cardiac infarct regions, accessory pathways, and the origins of ventricular tachycardia. http://dx.doi.org/10.1016/j.jelectrocard.2012.08.040
Assessing perception of new methods that represent ST deviation Bond RR, Finlay DD, Breen CJ, Nugent CD, Guldenring D, Martin E Computer Science Research Institute and School of Computing and Mathematics, University of Ulster, Belfast, Northern Ireland, UK Introduction: The ST Map is a new method to assess acute myocardial infarction (AMI). Although variations of the ST Map do exist, Philips Healthcare has been the first to integrate its approach into clinical practice. This study assessed student perception of the Philips ST Map when seen for the first time. Methods: The study comprised 27 students (age: 22.2 ± 3.79 years, 18 females, 7 males, 2 did not specify) studying on an undergraduate programme in clinical physiology (with a specialism in cardiology) at the University of Ulster. All students had formally studied electrocardiography. Prior to the study none of the students had been introduced to the ST Map. All students were given the same ST Map to interpret, which was an example of AMI. Although students were informed that the ST Map represented ST deviation, no explanation of the graphic was provided. Each student studied the ST Map for 2 min and subsequently completed a questionnaire. Results: Using the ST Map, 93% of students identified the lead with the largest ST elevation; however, only 44% identified the lead with the largest ST depression. Also, 85% correctly measured the elevation of lead V3 and only 44% correctly measured the depression of lead II. Thus, students found it easier to identify elevation, however, found it difficult to identify depression. This was due to the misleading placement of reference values (i.e., − 3.0 mm) in the graphic display. When asked to rate how easy the ST Map was to understand on a 10-point scale (1 = intuitive, 10 = counter-intuitive), the average rating was 7.44 ± 1.89 (mode = 8). Although 93% recognized the patient was having an AMI, 100% said training would be required to interpret ST Maps. When presented with four variations of the ST Map, 48% (plurality) of students preferred arrows to represent ST deviation as opposed to a six-sided polygon (hexagon). They also said the alternative positioning of reference values and the labels (e.g., anterior, septal) made the ST Map more intuitive.
Conclusion: It can be concluded that training is needed to interpret the Philips ST Map and that a number of graphical modifications may improve its design. This kind of study may lead to recommendations for the optimal display of the ST Map and in turn, its standardization. http://dx.doi.org/10.1016/j.jelectrocard.2012.08.041
ECG evidence of prior myocardial infarction improves the diagnostic performance of tests for left ventricular systolic dysfunction Robert A. Warner Tigard Research Institute, Tigard, OR, USA Background: The etiology of acute dyspnea can be either cardiac or noncardiac. If the former, the dyspnea is often associated with left ventricular systolic dysfunction (LVSD). We hypothesized that objective evidence of underlying heart disease increases the prior probability that patients with acute dyspnea is cardiac in origin and would therefore augment the diagnostic evaluation of these patients. Since accurate ECG evidence of prior myocardial infarction (MI) is prima facie evidence of underlying heart disease, we further hypothesized that evidence of prior MI by ECG increases the likelihood that acutely dyspneic patients have LVSD. Methods: We studied 371 patients (mean age = 59 years, 201 women) who presented to an emergency department with acute dyspnea. Of these, 272 (73%) had electronic recordings of their heart sounds (Audicor®, Inovise Medical, Inc., Portland, OR, USA) and 99 (27%) had measurements of brain natriuretic peptide (BNP). All patients had ECGs at their time of arrival and echocardiograms within 24 h of their time of arrival in the emergency department. We defined LVSD as an echocardiographic left ventricular ejection fraction b 50%. ECG evidence of prior MI consisted of a Selvester– Wagner ECG MI score ≥ 1 Results: The Table shows the diagnostic performances of the electronic S3 energy score and BNP for detecting LVSD in the entire group and in the patients with vs. without evidence of prior MI by ECG. All subjects
MI absent
MI present
5.66 98% 21% 4.44 4 × 10− 2
6.00 98% 16% 7.76 5 × 10−3
5.18 98% 35%
BNP (pg/ml) Threshold value 1740 Specificity 98% Sensitivity 10% Chi Square⁎ 28.8 Alpha⁎ 8 × 10- 8 ⁎ Compared to MI present.
1740 98% 11% 12.3 5 × 10- 4
779 98% 33%
S3 energy score Threshold value Specificity Sensitivity Chi Square⁎ Alpha⁎
Conclusions: Evidence of prior MI by ECG augments the detection of LVSD by electronic S3 recordings and by BNP. For both S3 energy and BNP measurements, the presence of prior MI by ECG lowers the diagnostic thresholds needed to achieve 98% specificity for LVSD and significantly increases the diagnostic sensitivity at that specificity. http://dx.doi.org/10.1016/j.jelectrocard.2012.08.042
Diffuse ST depression with ST elevation in AVR: Is this pattern specific for global ischemia due to left main coronary artery disease? Robert J. Knotts, James Wilson, Yochai Birnbaum Baylor College of Medicine, Houston, TX, USA Background: It has been reported that in patients with angina at rest, STsegment depression in eight or more body surface electrocardiograph
Poster Session 2 / Journal of Electrocardiology 45 (2012) 697–701
New 3D patient-specific morphing tool translates ECG/VCG waveforms into cardiac MRI and CT anatomy Peter Michael van Dam a, Michael Laks b, a Peacs, Arnhem, the Netherlands b David Geffen School of Medicine at UCLA, Los Angeles, USA Patient-specific heart and thorax models derived from MRI/CT images would increase the accuracy of the translationed ECG and VCG waveforms. Moreover, such models would also enable the quantitative analysis of the heart and thus support the diagnosis and treatment of the patient, e.g., identification of ischemic zones or ablation sites. Currently no computer tools are available to create these patient-specific heart and thorax models. Therefore we developed (semi)automatic morphing software that reconstructs the patient-specific heart and thorax geometry from MRI/CT. We created a new mathematical morphing approach to translate all the significant anatomical structures of the heart and thorax into mathematical algorithms. We used this approach because standard morphing techniques do not correctly model many of the heart structures, for example, the right ventricular septum connects at an acute angle. By using the reference point of the RVOT and the apex of the right ventricle, the acute angle of the right ventricle was located and thereby could be appropriately mathematical modeled. This technique was used to morph the whole heart, lung, liver, and thorax model. Ten adult patient-specific models have been reconstructed from MRI and CT (5 male, 5 female, 2 normal and 8 arrhythmia patients). On average only 12– 20 short-axis and 2–4 long-axis images were needed to make an accurate reconstruction. For the 10 reconstructed ventricles the mean deviation between MRI/CT contours and ventricular models were less 1.1 ± 0.9 mm. For the thorax and lungs the deviation was than 2.0 ± 1.5 mm. This novel 3D patient-specific morphing tool enables a new field of research and teaching creating an interactive relation between cardiac MRI and CT anatomy and ECG/VCG waveforms that translates them to localize cardiac infarct regions, accessory pathways, and the origins of ventricular tachycardia. http://dx.doi.org/10.1016/j.jelectrocard.2012.08.040
Assessing perception of new methods that represent ST deviation Bond RR, Finlay DD, Breen CJ, Nugent CD, Guldenring D, Martin E Computer Science Research Institute and School of Computing and Mathematics, University of Ulster, Belfast, Northern Ireland, UK Introduction: The ST Map is a new method to assess acute myocardial infarction (AMI). Although variations of the ST Map do exist, Philips Healthcare has been the first to integrate its approach into clinical practice. This study assessed student perception of the Philips ST Map when seen for the first time. Methods: The study comprised 27 students (age: 22.2 ± 3.79 years, 18 females, 7 males, 2 did not specify) studying on an undergraduate programme in clinical physiology (with a specialism in cardiology) at the University of Ulster. All students had formally studied electrocardiography. Prior to the study none of the students had been introduced to the ST Map. All students were given the same ST Map to interpret, which was an example of AMI. Although students were informed that the ST Map represented ST deviation, no explanation of the graphic was provided. Each student studied the ST Map for 2 min and subsequently completed a questionnaire. Results: Using the ST Map, 93% of students identified the lead with the largest ST elevation; however, only 44% identified the lead with the largest ST depression. Also, 85% correctly measured the elevation of lead V3 and only 44% correctly measured the depression of lead II. Thus, students found it easier to identify elevation, however, found it difficult to identify depression. This was due to the misleading placement of reference values (i.e., − 3.0 mm) in the graphic display. When asked to rate how easy the ST Map was to understand on a 10-point scale (1 = intuitive, 10 = counter-intuitive), the average rating was 7.44 ± 1.89 (mode = 8). Although 93% recognized the patient was having an AMI, 100% said training would be required to interpret ST Maps. When presented with four variations of the ST Map, 48% (plurality) of students preferred arrows to represent ST deviation as opposed to a six-sided polygon (hexagon). They also said the alternative positioning of reference values and the labels (e.g., anterior, septal) made the ST Map more intuitive.
Conclusion: It can be concluded that training is needed to interpret the Philips ST Map and that a number of graphical modifications may improve its design. This kind of study may lead to recommendations for the optimal display of the ST Map and in turn, its standardization. http://dx.doi.org/10.1016/j.jelectrocard.2012.08.041
ECG evidence of prior myocardial infarction improves the diagnostic performance of tests for left ventricular systolic dysfunction Robert A. Warner Tigard Research Institute, Tigard, OR, USA Background: The etiology of acute dyspnea can be either cardiac or noncardiac. If the former, the dyspnea is often associated with left ventricular systolic dysfunction (LVSD). We hypothesized that objective evidence of underlying heart disease increases the prior probability that patients with acute dyspnea is cardiac in origin and would therefore augment the diagnostic evaluation of these patients. Since accurate ECG evidence of prior myocardial infarction (MI) is prima facie evidence of underlying heart disease, we further hypothesized that evidence of prior MI by ECG increases the likelihood that acutely dyspneic patients have LVSD. Methods: We studied 371 patients (mean age = 59 years, 201 women) who presented to an emergency department with acute dyspnea. Of these, 272 (73%) had electronic recordings of their heart sounds (Audicor®, Inovise Medical, Inc., Portland, OR, USA) and 99 (27%) had measurements of brain natriuretic peptide (BNP). All patients had ECGs at their time of arrival and echocardiograms within 24 h of their time of arrival in the emergency department. We defined LVSD as an echocardiographic left ventricular ejection fraction b 50%. ECG evidence of prior MI consisted of a Selvester– Wagner ECG MI score ≥ 1 Results: The Table shows the diagnostic performances of the electronic S3 energy score and BNP for detecting LVSD in the entire group and in the patients with vs. without evidence of prior MI by ECG. All subjects
MI absent
MI present
5.66 98% 21% 4.44 4 × 10− 2
6.00 98% 16% 7.76 5 × 10−3
5.18 98% 35%
BNP (pg/ml) Threshold value 1740 Specificity 98% Sensitivity 10% Chi Square⁎ 28.8 Alpha⁎ 8 × 10- 8 ⁎ Compared to MI present.
1740 98% 11% 12.3 5 × 10- 4
779 98% 33%
S3 energy score Threshold value Specificity Sensitivity Chi Square⁎ Alpha⁎
Conclusions: Evidence of prior MI by ECG augments the detection of LVSD by electronic S3 recordings and by BNP. For both S3 energy and BNP measurements, the presence of prior MI by ECG lowers the diagnostic thresholds needed to achieve 98% specificity for LVSD and significantly increases the diagnostic sensitivity at that specificity. http://dx.doi.org/10.1016/j.jelectrocard.2012.08.042
Diffuse ST depression with ST elevation in AVR: Is this pattern specific for global ischemia due to left main coronary artery disease? Robert J. Knotts, James Wilson, Yochai Birnbaum Baylor College of Medicine, Houston, TX, USA Background: It has been reported that in patients with angina at rest, STsegment depression in eight or more body surface electrocardiograph