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Noninvasive Evaluation of Myocardial Ischemia and Left Ventricular Function
Linköping University, Department of Medicine and Health Sciences, Clinical Physiology . Linköping University, Faculty of Health Sciences.
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The general aim of this thesis was, following the path of the ischemic cascade, to evaluate the feasibility of some new non-invasive techniques for the detection of myocardial ischemia, the extent of infarcted myocardium, and for the quantification of systolic left ventricular function.

Reduced longitudinal myocardial velocity and displacement may be early signs of ischemia. We evaluated the diagnostic sensitivity and specificity of pulsed tissue Doppler for the detection of ischemia and scar during dobutamine stress testing and compared it with myocardial perfusion scintigraphy (SPECT) in patients with a history of unstable angina. Pulsed tissue Doppler was useful for objective quantification of left ventricular longitudinal shortening and for differentiation between patients with a normal, ischemic or necrotic myocardium.

The coronary flow velocity reserve (CFVR) of the left anterior descending artery (LAD) was studied with transthoracic Doppler echocardiography (TTDE) during adenosine stress. Patients with a clinical suspicion of stress induced myocardial ischemia were investigated, and the results were compared with the findings from SPECT. A CFVR >2 in the LAD could exclude significant coronary artery disease in a clinical setting, however, in cases with low CFVR, multiple cardiovascular and metabolic risk factors as well as epicardial coronary artery disease or microvascular dysfunction might be responsible. TTDE is a promising tool, e.g. for follow-up after coronary interventions or for evaluating endothelial function over time.

A third study focused on the importance of accurate and reproducible measurements of left ventricular volumes and ejection fraction (LVEF). Patients with known or suspected coronary artery disease with different levels of LVEF were enrolled. We compared the LVEF determined with an automatic echocardiographic method with manual planimetry, visual assessment of LVEF and with quantitative myocardial gated SPECT. The software using learned pattern recognition and artificial intelligence (AutoEF) applied on biplane apical echocardiographic views reduced the variation in measurements without increasing the time required. The method seems to be able to reduce variation in the assessment of LVEF in clinical patients, especially for less experienced readers.

We evaluated a new feature tracking software for its ability to detect infarcted myocardium on cine-MR images. Patients were selected based on the presence or absence of myocardial scar in the perfusion area of the LAD. The software tracked myocardial wall motion and allowed the calculation of velocity, displacement and strain in radial and longitudinal directions. Feature tracking of cine-MR images detected scar segments with transmurality >50% within the distribution of the LAD with 80% sensitivity and 86% specificity (radial strain), without the need for the administration of gadolinium-based contrast.

In summary, we have evaluated some of the noninvasive techniques in the wide array of diagnostic tools available for the diagnosis of ischemic heart disease. Their availability, low costs, freedom from radiation and repeatability are essential as well as their diagnostic ability.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press , 2009. , 74 p.
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1109
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:liu:diva-18315ISBN: 978-91-7393-675-0 (print)OAI: oai:DiVA.org:liu-18315DiVA: diva2:217955
Public defence
2009-05-27, Aulan, Länssjukhuset Ryhov, Jönköping, 13:00 (Swedish)
Opponent
Supervisors
Available from: 2009-05-18 Created: 2009-05-18 Last updated: 2009-08-21Bibliographically approved
List of papers
1. Pulsed tissue Doppler imaging for the detection of myocardial ischaemia, a comparison with myocardial perfusion SPECT
Open this publication in new window or tab >>Pulsed tissue Doppler imaging for the detection of myocardial ischaemia, a comparison with myocardial perfusion SPECT
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2004 (English)In: Clinical Physiology and Functional Imaging, ISSN 1475-0961, E-ISSN 1475-097X, Vol. 24, no 5, 289-295 p.Article in journal (Refereed) Published
Abstract [en]

In order to compare the diagnostic ability of pulsed tissue Doppler and myocardial perfusion Single Photon Emission Computed Tomography (SPECT) in patients with a history of unstable coronary artery disease, CAD, 26 patients, 22 men and four women, age 47-76 years, were investigated in a prospective study, 5-10 day after an episode of unstable angina. Tissue Doppler and two-dimensional echocardiography were performed during dobutamine stress testing and myocardial scintigraphy after bicycle exercise and at rest. Patients with a normal SPECT had higher peak systolic velocity during dobutamine infusion, 18.9 +/- 4.1 cm s(-1), than patients with ischaemia, 12.2 +/- 3.8 cm s(-1) (P<0.001) or scar, 8.8 +/- 3.0 cm s(-1) (P<0.01). In a territorial analysis the difference in peak systolic velocity between areas with a normal and abnormal SPECT was less apparent. Failure to achieve >/=13 cm s(-1) in mean-peak systolic velocity was the most accurate criterion for detection of significant CAD on SPECT. We conclude that pulsed tissue Doppler can be used for objective quantification of left ventricular wall motion during dobutamine stress testing and for identification of patients with CAD on SPECT but not for identification of regional ischaemia.

Keyword
Dobutamine, echocardiography, myocardial perfusion SPECT, tissue Doppler
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-18310 (URN)10.1111/j.1475-097X.2004.00564.x (DOI)15383086 (PubMedID)
Available from: 2009-05-18 Created: 2009-05-18 Last updated: 2017-12-13Bibliographically approved
2. Feasibility and diagnostic power of transthoracic coronary Doppler for coronary flow velocity reserve in patients referred for myocardial perfusion imaging
Open this publication in new window or tab >>Feasibility and diagnostic power of transthoracic coronary Doppler for coronary flow velocity reserve in patients referred for myocardial perfusion imaging
2008 (English)In: Cardiovascular Ultrasound, ISSN 1476-7120, E-ISSN 1476-7120, Vol. 6, no 12Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Myocardial perfusion imaging (MPI), using single photon emission computed tomography (SPECT) is a validated method for detecting coronary artery disease. Transthoracic Doppler echocardiography (TTDE) of flow at rest and during adenosine provocation has previously been evaluated in selected patient groups. We therefore wanted to compare the diagnostic ability of TTDE in the left anterior descending coronary artery (LAD) to that of MPI in an unselected population of patients with chest pain referred for MPI. Our hypothesis was that TTDE with high accuracy would identify healthy individuals and exclude them from the need for further studies, enabling invasive investigations to be reserved for patients with a high probability of disease.

METHODS: Sixty-nine patients, 44 men and 25 women, age 61 +/- 10 years (range 35-82), with a clinical suspicion of stress induced myocardial ischemia, were investigated. TTDE was performed at rest and during adenosine stress for myocardial scintigraphy.

RESULTS: We found that coronary flow velocity reserve (CFVR) determined from diastolic measurements separated normal from abnormal MPI findings with statistical significance. TTDE identified coronary artery disease, defined from MPI, as reversible ischemia and/or permanent defect, with a sensitivity of 60% and a specificity of 79%. The positive predictive value was 43% and the negative predictive value was 88%. There was an overlap between groups which could be due to abnormal endothelial function in patients with normal myocardial perfusion having either hypertension or diabetes.

CONCLUSION: TTDE is an attractive non-invasive method to evaluate chest pain without the use of isotopes, but the diagnostic power is strongly dependent on the population investigated. Even in our heterogeneous clinical cardiac population, we found that CFVR>2 in the LAD excluded significant coronary artery disease detected by MPI.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-18311 (URN)10.1186/1476-7120-6-12 (DOI)18373873 (PubMedID)
Available from: 2009-05-18 Created: 2009-05-18 Last updated: 2017-12-13Bibliographically approved
3. Computer-assisted determination of left ventricular endocardial borders reduces variability in the echocardiographic assessment of ejection fraction
Open this publication in new window or tab >>Computer-assisted determination of left ventricular endocardial borders reduces variability in the echocardiographic assessment of ejection fraction
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2008 (English)In: Cardiovascular Ultrasound, ISSN 1476-7120, Vol. 6, no 55Article in journal (Refereed) Published
Abstract [en]

Background: Left ventricular size and function are important prognostic factors in heart disease. Their measurement is the most frequent reason for sending patients to the echo lab. These measurements have important implications for therapy but are sensitive to the skill of the operator. Earlier automated echo-based methods have not become widely used. The aim of our study was to evaluate an automatic echocardiographic method (with manual correction if needed) for determining left ventricular ejection fraction (LVEF) based on an active appearance model of the left ventricle (syngo (R) AutoEF, Siemens Medical Solutions). Comparisons were made with manual planimetry (manual Simpson), visual assessment and automatically determined LVEF from quantitative myocardial gated single photon emission computed tomography (SPECT).

Methods: 60 consecutive patients referred for myocardial perfusion imaging (MPI) were included in the study. Two-dimensional echocardiography was performed within one hour of MPI at rest. Image quality did not constitute an exclusion criterion. Analysis was performed by five experienced observers and by two novices.

Results: LVEF (%), end-diastolic and end-systolic volume/BSA (ml/m(2)) were for uncorrected AutoEF 54 +/- 10, 51 +/- 16, 24 +/- 13, for corrected AutoEF 53 +/- 10, 53 +/- 18, 26 +/- 14, for manual Simpson 51 +/- 11, 56 +/- 20, 28 +/- 15, and for MPI 52 +/- 12, 67 +/- 26, 35 +/- 23. The required time for analysis was significantly different for all four echocardiographic methods and was for uncorrected AutoEF 79 +/- 5 s, for corrected AutoEF 159 +/- 46 s, for manual Simpson 177 +/- 66 s, and for visual assessment 33 +/- 14 s. Compared with the expert manual Simpson, limits of agreement for novice corrected AutoEF was lower than for novice manual Simpson (0.8 +/- 10.5 vs. -3.2 +/- 11.4 LVEF percentage points). Calculated for experts and with LVEF (%) categorized into < 30, 30-44, 45-54 and >= 55, kappa measure of agreement was moderate (0.44-0.53) for all method comparisons (uncorrected AutoEF not evaluated).

Conclusion: Corrected AutoEF reduces the variation in measurements compared with manual planimetry, without increasing the time required. The method seems especially suited for unexperienced readers.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-16221 (URN)10.1186/1476-7120-6-55 (DOI)
Available from: 2009-02-19 Created: 2009-01-09 Last updated: 2009-08-19Bibliographically approved
4. Feature tracking of cine-MRI identifies left ventricular segments with myocardial scar
Open this publication in new window or tab >>Feature tracking of cine-MRI identifies left ventricular segments with myocardial scar
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

Background: The aim of the study was to apply a new feature tracking software (Diogenes MRI, Tomtec GmbH, Unterschliessheim, Germany) on cine-MR images to evaluate its utility and ability to detect infarcted myocardium and to assess the transmural extent of scar without the need for administering intravenous gadolinium-based contrast agents.

Methods: Thirty patients (3 women and 27 men) were selected based on the presence or absence of extensive myocardial scar in the perfusion area of the left anterior descending coronary artery (LAD) but not in remote areas. Seventeen had a scar transmurality >75% in at least one segment belonging to the LAD area (scar patients) and thirteen had scar <1% in this area or in other parts of the myocardium (non-scar patients). The software tracked the motion of the wall through the entire cardiac cycle using two different techniques. Velocity, displacement and strain were calculated in 48 points in the longitudinal direction, tangential to the endocardial outline, and in the radial direction, perpendicular to the tangent.

Results: In the scar patients, LAD segments showed lower functional measures than remote segments. The remote segments in the scar group showed, in turn, lower functional measures than the remote segments in the non-scar group. Receiver-operatorcharacteristic (ROC) curves were constructed for all measurements. Best area-undercurve was for radial strain, 0.89, where a cut-off value of 38.8% had 80% sensitivity and 86% specificity for the detection of a segment with scar transmurality >50% in the LAD distribution. As a percentage of the mean, intraobserver variability was for radial measures 16-14-26% for displacement-velocity-strain and for the corresponding interobserver measurements 13-12-18%.

Conclusions: With the presented method, we show for the first time its ability to detect scar segments with various transmurality already from an analysis of cine-MRI, without the need for the administration of gadolinium-based contrast. The accuracy and repeatability of the radial functional measurements is satisfactory and global measures agree with other aspects of global left ventricular function.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-18313 (URN)
Available from: 2009-05-18 Created: 2009-05-18 Last updated: 2013-09-11Bibliographically approved

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