Preservation of Right Ventricular Contractility After Transient Phenylephrine‐Induced Pressure Overload in Swine
Bibliographic record
Abstract
Objective We have previously demonstrated that a transient phenylephrine (PE)‐induced rise in systemic arterial blood pressure leads to reversible left ventricular (LV) systolic dysfunction in the absence of ischemia (i.e., “stretch‐induced stunning”). However, the extent to which this phenomenon occurs in the right ventricle (RV) is unclear. Accordingly, the present study was designed to assess changes in pulmonary artery (PA) pressure and RV function during and after systemic administration of PE in swine. Methods Closed‐chest propofol‐anesthetized swine (n=5) were instrumented with a Swan‐Ganz catheter and an admittance catheter for continuous measurement of PA pressure, RV pressure, and RV volume (ADV500; Transonic SciSense, Inc.). Ventricular end‐diastolic and end‐systolic volumes were assessed by multi‐detector computed tomography with iodinated contrast (1 mL/kg at 4 mL/s) before, during, and 30‐minutes after transient pressure overload elicited by a 1‐hour intravenous infusion of PE (18 mg/hour). Load‐independent RV systolic function was derived from RV pressure‐volume loops collected during inferior vena cava occlusion at baseline and 30 min after PE. Results PE elicited a significant rise in PA pressure (27±1/14±1 to 43±1/23±31mmHg; p<0.05) and RV pressure (25±2/3±1 to 44±2/8±2 mmHg; p<0.05) that normalized 30‐minutes after the end of the infusion period (PA: 28±1/11±1 mmHg; RV: 29±5/4±2 mmHg). This was accompanied by a significant increase in RV end‐diastolic and end‐systolic volumes and decrease in RV ejection fraction that tended to persist 30‐minutes after cessation of PE ( Table; top panel ). However, load‐dependent (dP/dt max ) and load‐independent (ESPVR and PRSW) parameters of RV systolic function were preserved after PE‐induced TPO ( Table; bottom panel ). Conclusions Despite causing a significant rise in RV preload volume and pressure, transient PE‐induced pressure overload is not associated with RV contractile dysfunction during the post‐infusion period. The absence of stretch‐induced stunning in the RV may be linked to inherent differences in compliance relative to the LV as well as a diminished pressor response to PE in the pulmonary vs. systemic circulation.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".