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Generating a Pulsatile Pulmonary Flow after Fontan Operation by Means of Computational Fluid Dynamics (CFD)

Ghoreyshi, Mostafa | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 41588 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Saidi, Mohamad Said; Firoozabadi, Bahar; Navaee Shirazei, Mohammad Ali
  7. Abstract:
  8. This study considers blood flow in total cavopulmonary connection (TCPC) morphology, which is created in Fontan surgical procedure in patients with single ventricle heart disease. Ordinary process of TCPC operation reduces the pulmonary blood flow pulsatility; because of right ventricle being bypassed. This phenomenon causes a lot of side effects for patients. A cardiac surgeon has suggested that keeping main pulmonary artery (MPA) partially open, would increase pulmonary flow pulsations. MPA gets closed in ordinary TCPC operation. The purpose of current study is to verify the effects of keeping MPA partially open on pulmonary flow pulsations, by means of computational fluid dynamics (CFD). The 3-D geometry is reconstructed from CT Angiography (CTA) scan of a patient who has undergone an ordinary TCPC procedure. The stenosed MPA or pulmonary stenosis (PS) is virtually added to the original geometry. Inlet velocity profiles of superior vena cava (SVC) and inferior vena cava (IVC) during a cardiac cycle are obtained from Echocardiography data of the same patient. The antegrade flow (AF) profile coming through PS is obtained from a general pressure profile of left ventricle, assuming a linear relationship between pressure difference and flow rate. Left and right pulmonary artery (LPA and RPA) outlets are assumed as pressure outlets with values that make a usual flow split (about 45% to LPA). Flow field is studied in six different models in which average AF gradually changes from 0% (model 1) to 14% (model 6) of total cardiac flow. The main studied parameter in pulmonary arteries is pulsatility index (PI) defined as, Qmax-Qmin/Qmean. Results show that adding AF increases PI in both LPA and RPA. Model 6 produces an increase of about 140% in PI of LPA. Also, despite AF flow is most likely to go to LPA, it is observed that adding AF mostly increases RPA average flow rate. This phenomenon is explained with respect to flow patterns. The other important parameter is power loss, which increases in an almost 2nd order relationship with respect to average AF. But, total energy loss coefficient (Ce), which shows nondimensionalized power loss with respect to entering kinetic energy of fluid, does not change a lot. We conclude that adding antegrade flow is an impressive way to increase pulsations of pulmonary flow. Meanwhile energy losses should be considered as an important factor to help us getting an optimum combination.

  9. Keywords:
  10. Numerical Method ; Computational Fluid Dynamics (CFD) ; Multiscale Modeling ; Fontan Operation ; Total Cavopulmonary Connect (TCPC) ; Flow Pulsations ; Pulmonary Arteries

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