Estimation of left atrial pressure using venous pressure corrected by the right-to-left ventricular ejection fraction ratio on three-dimensional echocardiography

Study objective: Accurate assessment of left atrial pressure (LAP) is essential for managing advanced heart failure. However, routine evaluation of LAP using an invasive pulmonary artery catheter is not recommended in clinical practice, while non-invasive echocardiographic indices exhibit substantial variability. Right atrial pressure (RAP) can be used to estimate LAP, as LAP has a linear relationship to RAP when right and left ventricular functions are in a steady state. If either ventricular function deteriorates, however, a corresponding volume shift occurs between the systemic and pulmonary circulations. This shift can alter the relationship between LAP and RAP, thereby impairing the accuracy of LAP estimation based solely on RAP. Under such conditions, incorporating the ratio of right- to left-ventricular function into RAP may allow more accurate estimation of LAP. Given that peripheral venous pressure (PVP) has gained attention as an indicator of volume status in heart failure management and is strongly associated with RAP, PVP may serve as a surrogate for RAP in estimating LAP. This study therefore aimed to investigate whether measured venous pressure, either RAP or PVP, when combined with the three-dimensional echocardiography-based biventricular ejection fraction ratio, can accurately predict LAP in a canine heart failure model. Hypothesis: We hypothesized that LAP can be expressed as α·RAP·(RVEF/LVEF)+β or γ·PVP·(RVEF/LVEF)+θ where α, β, γ and θ are constants, and RVEF and LVEF represent right and left ventricular ejection fraction, respectively. Methodology: A chronic heart failure model was established in 7 beagle dogs by pacing-induced cardiomyopathy. LAP was directly measured by fluid-filled catheter under thoracotomy (n=5) or estimated using pulmonary artery wedge pressure via pulmonary artery catheter (n=2) in closed-chest model. RAP and PVP were also simultaneously measured using fluid-filled catheter. Hemodynamic conditions were modified by four sequential stages of blood withdrawal (3–5 mL/kg per step). In addition, pulmonary embolism was induced by infusing microbeads (n = 4) through a central venous line to further impair right heart failure and alter the balance of biventricular function. The four-stage serial blood withdrawal (3–5 mL/kg per step) was then repeated. Three-dimensional echocardiography was performed to measure LVEF and RVEF. Results: Forty-four data sets were obtained. LAP, RAP·(RVEF/LVEF) and PVP·(RVEF/LVEF) decreased with blood withdrawal; 19.9±4.1 to 9.8±2.5, 13.3±7.2 to 4.5±2.6, 13.5±6.1 to 7.7±4.2, respectively. In linear regression analysis, LAP was expressed as 0.35·RAP·(RVEF/LVEF)+11.9 (R 2 =0.16, p value of slope =0.004, p value of intercept < 0.001) or 0.36·PVP·(RVEF/LVEF)+11.2 (R 2 =0.13, p value of slope =0.011, p value of intercept < 0.001) were significantly associated with LAP. In the receiver operating characteristic (ROC) curve analysis to judge if LAP is over 18 mmHg, RAP·(RVEF/LVEF) and PVP·(RVEF/LVEF) yielded an area under the curve (AUC) of 0.693 (95% confidence interval, CI, 0.509–0.878) and 0.642 (95% CI, 0.457–0.827), respectively. Conclusion: The variables RAP and PVP, after being individually multiplied by the RVEF/LVEF ratio derived from three-dimensional echocardiography, both demonstrated a significant linear association with LAP. These non-invasive methods potentially allow the estimation of LAP by adjusting constants. Funding sources: The Grants-in-Aid for Scientific Research (KAKENHI, Grant Number: 24K23422) This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.