Establishing Background Pathologic Changes of Valve Replacement Surgery in Sheep

Jill T.Schappa Faustich, John Carney, Matthew T Lahti, Benjamin L. Zhang, Richard W. Bianco

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


PURPOSE: Sheep are the standard preclinical model for assessing safety of novel replacement heart valves, yet the anatomic and pathologic effects of invasive surgery, including those involving cardiopulmonary bypass (CPB), are unknown. Thus, we aimed to determine the gross, hematologic and biochemical effects of sham mitral and aortic replacement valve procedures in sheep to establish a useful control for evaluation of novel replacement valves.

METHODS: Six control sheep were examined without any surgical intervention. Six sham mitral valve replacements (MVR) and six sham aortic valve replacements (AVR) were performed on 12 sheep. Complete blood counts and serum biochemistry were performed throughout the study. Sheep were sacrificed with a necropsy performed at 90 days.

RESULTS: Renal infarcts (RIs) were the most frequently observed lesion, averaging 4.7 in control sheep, 2.5 with MVR and 5.8 with AVR. The number of infarcts strongly correlated with total estimated area of infarcted kidney (r = .84, p < .01). Additional cardiac interventions were significantly correlated with increased numbers of RIs (r = .85, p < .01). There was no correlation between number of RIs and time on CPB, or between AVR and MVR procedures.

CONCLUSION: The sheep model for AVR and MVR requires invasive surgery and CPB, which are associated with background anatomic and pathologic changes, especially in cases with additional surgical cardiac interventions. These findings serve as a critical control for future evaluation and development of novel replacement valves in order to distinguish device-related safety issues from expected outcomes of the surgical procedure and normal background changes in sheep.

Original languageEnglish (US)
Pages (from-to)181-190
Number of pages10
JournalCardiovascular Engineering and Technology
Issue number1
StatePublished - Feb 2022

Bibliographical note

Funding Information:
We thank Peggy Norris and the UMN Experimental Surgical Services Laboratory staff and students with their help in conducting the animal experiments; the UMN Research Animal Resources staff for their care and support of the research animals used in this study. This research was funded by W. L. Gore & Associates, Inc. The data that support the findings of this study are available from the corresponding author, JPC, upon reasonable request. JSF, JPC, MTL, BLZ and RWB declare that they have no conflicts of interest. The authors alone are responsible for the content and writing of the article. RWB is a paid consultant of W.L. Gore & Associates, Inc. JSF, JPC, MTL and BLZ have no disclosures. The animals used in this work received care in compliance with the protocols approved by the laboratory?s Institutional Animal Care and Use Committee in accordance with the guidelines for humane care.

Funding Information:
This research was funded by W. L. Gore & Associates, Inc.

Publisher Copyright:
© 2021, The Author(s).


  • Animal model
  • Cardiopulmonary bypass
  • Preclinical
  • Renal infarcts
  • Sheep
  • Valve replacement surgery


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