Pulsed‐Wave Doppler Blood Flow Through the Pulmonary Trunk as a Valuable Method to Determine Cardiac Output Following Myocardial Infarction
Bibliographic record
Abstract
Background Cardiac output (CO) is a valuable measure of cardiac function, both clinically and in small animal models of cardiac injury (e.g., myocardial infarction; MI). As the product of stroke volume and heart rate, CO can be estimated from cardiac volumes acquired from one (i.e., M‐Mode) and two (i.e., single plane ellipsoid formula) dimensional echocardiographic images of the left ventricle (LV). Critically, deformations of the LV following MI (e.g., non‐uniform composition/contractile properties) invalidate the mathematical assumptions imperative to the accurate estimation of CO. Thus, the purpose of this study was to determine if pulsed‐wave Doppler flow through the pulmonary trunk – a structure independent of the remodeling in the ischemic LV – provided an alternative, and more accurate, method to quantify forward CO following MI. Methods Variations in CO were induced either by transverse aortic constriction (TAC) or MI. CO was calculated from classical LV‐dependent methods (M‐Mode and the single‐plane ellipsoid 2D formula), pulsed‐wave Doppler through the pulmonary trunk (pulmonary flow), and intra‐thoracic flow probe. Results In healthy mice, all three echocardiography methods (M‐Mode, 2D and pulmonary flow) correlated well with flow‐probe derived CO as confirmed by Bland‐Altman analysis. In MI, only pulmonary flow demonstrated both accuracy and precision, retaining the expected positive bias and demonstrating <10mls/min range difference compared to the 20–25mls/min range for either LV‐dependent method. Pulmonary flow CO in MI also demonstrated reduced inter‐ and intra‐user variability, and both an improved internal and external agreement (correlation coefficients) when compared against either M‐Mode or 2D CO calculations. Conclusions Pulmonary flow CO calculated from pulsed‐wave Doppler through the pulmonary trunk was an improved method of estimating CO over LV‐dependent formulae following MI. There was also a significant correlation between pulmonary flow, M‐Mode and 2D measures in healthy and TAC mice, demonstrating pulmonary flow was a comparable estimation of CO in these non‐ischemic conditions. This is relevant in the continuing attempt to more accurately assess cardiac function and particularly, grade preclinical therapies for treating MI. Support or Funding Information This work was supported by the Canadian Institutes of Health Research grant (MOP 111159) to J.A. Simpson. J.A. Simpson is a New Investigator of the Heart and Stroke Foundation of Canada.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 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".