A comparison of the classical and modified forms of the continuity equation in the On-X prosthetic heart valve in the aortic position.
Bibliographic record
Abstract
BACKGROUND AND AIM OF THE STUDY: The use of echocardiography to determine prosthetic valve hemodynamics has become generally accepted; however, there are still many differing methodologies in use. The continuity equation, which uses the ratio of the subaortic and transaortic velocity-time integrals for determining aortic effective orifice area (EOA), has been established as an accurate method. Another method using the more easily measured peak velocities in ratio has also been employed. These methods were compared to determine if the simpler method gave equivalent results. METHODS: Early postoperative echocardiographic data on prosthetic valves from the MCRI Multicenter Trial were used to compare the two methods of calculating EOA (A2). Results using the two methods were compared by paired t-tests, the Wilcoxon signed rank test, regression and Bland-Altman analysis. RESULTS: Despite a good correlation between the two methods (r = 0.91), results were different when compared by a paired t-test. On average, results by the modified method were 0.2 cm2 lower, but in 28% of cases they were in fact higher than the classical method. CONCLUSION: The modified continuity equation based on the peak velocity ratio does not give the same result as the classical formula based on the velocity-time ratio. The modified method cannot reliably be substituted for the classical method in normally functioning On-X valves.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.006 | 0.019 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".