Kumar, N (2008) Assessment of LV systolic function by velocity vector imaging. Masters thesis, Christian Medical College, Vellore.
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Abstract
INTRODUCTION : Cardiovascular disease is one of the leading causes of morbidity and mortality worldwide. Our country has faced an epidemic of ischemic heart disease over the past decade. Hence new tools for diagnosis and prognostication in heart disease are constantly being developed and evaluated. Measurement of left ventricular (LV) function has a central role in the assessment of a wide variety of cardiac diseases. While measurement of systolic function is almost always done as a routine, detailed evaluation of diastolic function is done in selected instances. The degree of LV systolic dysfunction is a powerful predictor of cardiovascular morbidity and mortality and is often crucial in deciding therapy. Clinical evaluation alone has been shown to have poor sensitivity and specificity to detect LV dysfunction, while the electrocardiogram and chest Xray have only limited utility. BACKGROUND : Assessment of LV systolic function is an important parameter in evaluation of cardiac disease. Echocardiography is the most widely used non invasive imaging modality in the assessment of LV function. Current methods of assessing LV systolic function have limitations. Velocity vector imaging (VVI) is a new modality that uses 2D (B-mode) images to determine tissue motion and velocity by application of a tracking algorithm. In this study, we assessed the utility of VVI in the measurement of LV systolic function in comparison to radionuclide imaging and standard 2D echo. METHODS : We measured global and regional LV systolic function by ejection fraction (EF) in 49 patients using VVI, standard 2D echo and nuclear imaging (SPECT). Patients were categorized as normal; mild, moderate or severe LV systolic dysfunction based on American Society of Echocardiography classification. The results were analyzed by appropriate statistical tests for correlations. RESULTS : The mean EF for the study population as measured by VVI was 35 ± 12.08%, as compared to 54.2 ± 19.51% with SPECT (p<0.001 vs VVI) and 50.3 ± 8.92% with 2D echo(p<0.001 vs VVI). There was a positive linear correlation between EF measured by VVI and the other modalities (Pearsons correlation coefficient 0.577 for SPECT and 0.573 for 2D; p = 0.01). However, VVI systematically underestimated the EF in comparison to SPECT. There were significantly greater proportion of patients classified as having moderate or severe LV systolic dysfunction by VVI (75.5%) when compared to SPECT (34.7%; p=0.026). We derived a correction factor to calculate SPECT EF from VVI EF: EF (SPECT) = EF (VVI) x0.9 + 21 or approximately VVI (EF) +20. There was good inter-observer correlation for EF measured by SPECT. CONCLUSION : VVI was found to underestimate the ejection fraction as compared to that measured by gated SPECT. A correction factor can be incorporated into the VVI algorithm to improve its accuracy.
| Item Type: | Thesis (Masters) |
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| Uncontrolled Keywords: | LV systolic function ; velocity vector imaging. |
| Subjects: | MEDICAL > Cardiology |
| Depositing User: | Kambaraman B |
| Date Deposited: | 10 Jul 2017 22:13 |
| Last Modified: | 10 Jul 2017 22:13 |
| URI: | http://repository-tnmgrmu.ac.in/id/eprint/1347 |
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