Evaluation of flow-modulation approaches in ventricular assist devices using an in-vitro endothelial cell culture model

Academic Article


  • BACKGROUND: Continuous-flow ventricular assist devices (CF-VADs) produce non-physiologic flow with diminished pulsatility, which is a major risk factor for development of adverse events, including gastrointestinal (GI) bleeding and arteriovenous malformations (AVMs). Introduction of artificial pulsatility by modulating CF-VAD flow has been suggested as a potential solution. However, the levels of pulsatility and frequency of CF-VAD modulation necessary to prevent adverse events are currently unknown and need to be evaluated. METHODS: The purpose of this study was to use human aortic endothelial cells (HAECs) cultured within an endothelial cell culture model (ECCM) to: (i) identify and validate biomarkers to determine the effects of pulsatility; and (ii) conclude whether introduction of artificial pulsatility using flow-modulation approaches can mitigate changes in endothelial cells seen with diminished pulsatile flow. Nuclear factor erythroid 2–related factor 2 (Nrf-2)–regulated anti-oxidant genes and proteins and the endothelial nitric oxide synthase/endothelin-1 (eNOS/ET-1) signaling pathway are known to be differentially regulated in response to changes in pulsatility. RESULTS: Comparison of HAECs cultured within the ECCM (normal pulsatile vs CF-VAD) with aortic wall samples from patients (normal pulsatile [n = 5] vs CF-VADs [n = 5]) confirmed that both the Nrf-2–activated anti-oxidant response and eNOS/ET-1 signaling pathways were differentially regulated in response to diminished pulsatility. Evaluation of 2 specific CF-VAD flow-modulation protocols to introduce artificial pulsatility, synchronous (SYN, 80 cycles/min, pulse pressure 20 mm Hg) and asynchronous (ASYN, 40 cycles/min, pulse pressure 45 mm Hg), suggested that both increased expression of Nrf-2–regulated anti-oxidant genes and proteins along with changes in levels of eNOS and ET-1 can potentially be minimized with ASYN and, to a lesser extent, with SYN. CONCLUSIONS: HAECs cultured within the ECCM can be used as an accurate model of large vessels in patients to identify biomarkers and select appropriate flow-modulation protocols. Pressure amplitude may have a greater effect in normalizing anti-oxidant response compared with frequency of modulation.
  • Digital Object Identifier (doi)

    Pubmed Id

  • 18019642
  • Author List

  • Haglund TA; Rajasekaran NS; Smood B; Giridharan GA; Hoopes CW; Holman WL; Mauchley DC; Prabhu SD; Pamboukian SV; Tallaj JA
  • Start Page

  • 456
  • End Page

  • 465
  • Volume

  • 38
  • Issue

  • 4