Commentary: Can in vitro valve testing reliably predict clinical outcomes?
Bibliographic record
Abstract
Central MessageNew generations of aortic valve protheses should always aim at better clinical outcomes, whether physics, hemodynamic, or other parameters also mirror those changes.See Article page 43. New generations of aortic valve protheses should always aim at better clinical outcomes, whether physics, hemodynamic, or other parameters also mirror those changes. See Article page 43. Hatoum and colleagues1Hatoum H. Ahn S. Lilly S. Maureira P. Crestanello J. Thourani V.H. et al.Flow dynamics of surgical and transcatheter aortic valves: past to present.J Thorac Cardiovasc Surg Open. 2022; 9: 43-56Scopus (1) Google Scholar have published an elegant paper showing the hemodynamic parameters and flow characteristics downstream of various transcatheter and surgical aortic valve protheses. They included extensive fluid dynamic considerations by testing the valves in an in vitro environment, using a pulse duplicator. The authors measured the pressure gradient, effective orifice area (EOA), as well as the Reynolds shear stress (RSS) and viscous shear stress (VSS) (those last 2 are used to analyze the degree of turbulence in the downstream flow) among the protheses tested. They demonstrated that the SJM mechanical valve (Abbott Laboratories, Chicago, Ill) had the greatest EOA and that the Hancock II (Medtronic, Minneapolis, Minn) displayed the greatest range of RSS and VSS among the surgical valves. Regarding the transcatheter valves, the Evolut (Medtronic) displayed the greatest range of RSS and VSS compared with the SAPIEN 3 (Edwards Lifesciences, Irvine, Calif). The authors concluded that these features should be considered in the design of future aortic valves prothesis, and that the evolution of the aortic valve protheses have not kept up with improvements in physics.1Hatoum H. Ahn S. Lilly S. Maureira P. Crestanello J. Thourani V.H. et al.Flow dynamics of surgical and transcatheter aortic valves: past to present.J Thorac Cardiovasc Surg Open. 2022; 9: 43-56Scopus (1) Google Scholar The obvious question the reader should consider is whether better hemodynamic features translate into better clinical outcomes for patients undergoing aortic valve replacement? Better fluid dynamics do not always predict better clinical outcomes. For example, hemodynamics parameters of the Toronto SPV bioprothesis predicted excellent results; however, the valve was challenged by suboptimum durability, and reoperation was associated with a high complexity.2David T.E. Feindel C.M. Bos J. Ivanov J. Armstrong S. Aortic valve replacement with Toronto SPV bioprosthesis: optimal patient survival but suboptimal valve durability.J Thorac Cardiovasc Surg. 2008; 135: 19-24Abstract Full Text Full Text PDF PubMed Scopus (64) Google Scholar,3Dellgren G. Feindel C.M. Bos J. Ivanov J. David T.E. Aortic valve replacement with the Toronto SPV: long-term clinical and hemodynamic results.Eur J Cardiothorac Surg. 2002; 21: 698-702Crossref PubMed Scopus (41) Google Scholar Similarly, the Hancock II bioprothesis, despite of in vitro predictions of high pressure gradient, RSS, VSS, and low EOA, has demonstrated great durability.1Hatoum H. Ahn S. Lilly S. Maureira P. Crestanello J. Thourani V.H. et al.Flow dynamics of surgical and transcatheter aortic valves: past to present.J Thorac Cardiovasc Surg Open. 2022; 9: 43-56Scopus (1) Google Scholar,4David T.E. Armstrong S. Maganti M. Hancock II bioprosthesis for aortic valve replacement: the gold standard of bioprosthetic valves durability?.Ann Thorac Surg. 2010; 90: 775-781Abstract Full Text Full Text PDF PubMed Scopus (144) Google Scholar,5David T.E. Armstrong S. Sun Z. Clinical and hemodynamic assessment of the Hancock II bioprosthesis.Ann Thorac Surg. 1992; 54 (discussion 667-8): 661-667Abstract Full Text PDF PubMed Scopus (62) Google Scholar We are not implying that valve hemodynamics in such testing should be ignored; however, findings should be taken in context, and perhaps we should re-examine the implications of laboratory predictions. We have not yet reached the ideal aortic valve substitute. However, we have been improving clinical outcomes despite a possible lag on the physics features. Today, we can pick an aortic valve prothesis according to the preferences and characteristics of the patient, making each choice unique and individual. Patients at any age are able to choose the valve that best fits them, whether with a surgical or transcatheter approach, whether with a bioprothesis or a mechanical prothesis or a Ross procedure. And, for the future, the new generation of aortic valve protheses should always aim at better clinical outcomes, whether physics, hemodynamic, or other parameters mirror those changes. Flow dynamics of surgical and transcatheter aortic valves: Past to presentJTCVS OpenVol. 9PreviewTo perform an in vitro characterization of surgical aortic valves (SAVs) and transcatheter aortic valves (TAVs) to highlight the development of the flow dynamics depending on the type of valve implanted and assess the basic differences in the light of flow turbulence and its effect on blood damage likelihood and hemodynamic parameters that shed light on valve performance. Full-Text PDF Open Access
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.002 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.000 | 0.002 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".