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Assessment of Pulmonary Insufficiency using Energy-Based Endpoints and 4D Phase Contrast MR Imaging

Lee, Namheon
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1384865927

Abstract Details

2013, PhD, University of Cincinnati, Engineering and Applied Science: Mechanical Engineering.
A congenital heart disease (CHD), such as tetralogy of Fallot (TOF) and aortic valve disease requiring the Ross procedure (pulmonary autograft), causes fatal right heart dysfunction over time and often sudden death for a patient. Patients who have undergone the repair surgery often confront pulmonary insufficiency (PI) which is the main life-threatening postoperative dysfunction. PI, which is caused mainly due to the dysfunctional pulmonary valve, results severe pulmonary regurgitation, right ventricular (RV) dilatation, and elevated RV and pulmonic pressure over time. Therefore, re-operation, such as pulmonary valve replacement surgery in patients, has to be performed at the right time to correct PI. Since the appropriate time for intervention is critical for patients with right heart dysfunction, the hemodynamics of the RV and pulmonary arteries (PAs) has to be carefully monitored throughout the lifetime of the patient. However, due to the complexity of symptoms, it is sometimes difficult to diagnose the progress of the diseases accurately using existing cardiac indices, such as RV end-diastolic volume indexed to body area surface (BSA) and end-systolic pressure. Recently, energy-based endpoints that couple RV volume, RV pressure data, and PA flow conditions, such as RV stroke work indexed to BSA (SWI), energy transfer ratio (eMPA) between the RV and the main PA (MPA), and energy loss in the branch PAs, were investigated by our group. In this research the proposed endpoints were calculated and compared between a group of patients with abnormal RV-PA physiology and control subjects with normal RV-PA physiology. Energy-based endpoints mentioned earlier to quantify the RV-PA pathophysiology of a patient, require accurate measurement of cardiac blood flow and pressure data in a current clinical setting. Consequently, invasive cardiac catheterization, which is not a standard of care procedure for repaired CHD patients, is often required for those measurements. To circumvent this issue, in this research we developed a methodology to calculate the pressure drop in the branch PAs non-invasively using 4D phase contrast magnetic resonance imaging (PC MRI) data, i.e. three directional velocity data over time. This enabled us to obtain time varying pressure-flow data, which, in turn, allowed us to calculate energy loss in the branch PAs. As a result, it can eliminate the need for invasive cardiac catheterization procedure; thus, further extending the applicability of energy-based endpoints. Our results showed that RV SWI of the patient group (0.176 ± 0.055 J/m2) was significantly higher by 93.4 % (p<0.01) than that of the control group (0.091± 0.030 J/m2). The mean eMPA of the patient group (0.56 ± 0.33) was significantly lower than that of the control group (1.56 ± 0.85) with p<0.01, despite the fact that the patient group had a significantly higher RV SWI than the control group (0.21 ± 0.10 J/m2 vs. 0.09 ± 0.04 J/m2; p<0.02). Further, the non-invasively computed pressure drop in the branch PA using 4D PC MRI measurements for the patient group was order of magnitude larger than the control group. Likewise, the total energy loss in the RPA and LPA for the patient group was also order of magnitude larger than the control group. Based on our results, we believe that energy-based endpoints we proposed, RV SWI, eMPA, and energy loss in the branch PAs, can distinguish the RV-PA abnormal physiology from the normal physiology. These can be useful clinical measures to evaluate the PA hemodynamics for longitudinal clinical assessment of patients.
Rupak Banerjee, Ph.D, P.E. (Committee Chair)
Kan Hor, M.D. (Committee Member)
Michael Taylor, M.D., Ph.D. (Committee Member)
J. Kim, Ph.D. (Committee Member)
Yijun Liu, Ph.D. (Committee Member)
173 p.
Mechanics
Pulmonary insufficiency; Energy-based endpoints; 4D phase contrast MRI; Cardiac mechanics; CFD

Recommended Citations

Citations

  • Lee, N. (2013). Assessment of Pulmonary Insufficiency using Energy-Based Endpoints and 4D Phase Contrast MR Imaging [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1384865927

    APA Style (7th edition)

  • Lee, Namheon. Assessment of Pulmonary Insufficiency using Energy-Based Endpoints and 4D Phase Contrast MR Imaging. 2013. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1384865927.

    MLA Style (8th edition)

  • Lee, Namheon. "Assessment of Pulmonary Insufficiency using Energy-Based Endpoints and 4D Phase Contrast MR Imaging." Doctoral dissertation, University of Cincinnati, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1384865927

    Chicago Manual of Style (17th edition)

ucin1384865927
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© 2013, all rights reserved.
This open access ETD is published by University of Cincinnati and OhioLINK.