Role of vortices in growth of microbubbles at mitral mechanical heart valve closure

Edmond Rambod, Masoud Beizai, David J. Sahn, Morteza Gharib

Research output: Contribution to journalArticle

8 Scopus citations

Abstract

This study is aimed at refining our understanding of the role of vortex formation at mitral mechanical heart valve (MHV) closure and its association with the high intensity transient signals (HITS) seen in echocardiographic studies with MHV recipients. Previously reported numerical results described a twofold process leading to formation of gas-filled microbubbles in-vitro: (1) nucleation and (2) growth of micron size bubbles. The growth itself consists of two processes: (a) diffusion and (b) sudden pressure drop due to valve closure. The role of diffusion has already been shown to govern the initial growth of nuclei. Pressure drop at mitral MHV closure may be attributed to other phenomena such as squeezed flow, water hammer and primarily, vortex cavitation. Mathematical analysis of vortex formation at mitral MHV closure revealed that a closing velocity of approximately 12 m/s can induce a strong regurgitant vortex which in return can instigate a local pressure drop of about 0.9 atm. A 2D experimental model of regurgitant flows was used to substantiate the impact of vortices. At simulated flow and pressure conditions, a regurgitant vortex was observed to drastically enlarge micron size hydrogen bubbles at its core.

Original languageEnglish (US)
Pages (from-to)1131-1145
Number of pages15
JournalAnnals of Biomedical Engineering
Volume35
Issue number7
DOIs
StatePublished - Jul 1 2007

Keywords

  • Cavitation
  • HITS
  • Mechanical heart valves
  • Microbubble growth
  • Nucleation
  • Vortex formation

ASJC Scopus subject areas

  • Biomedical Engineering

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