Abstract Body (Do not enter title and authors here): Background: Cardiorenal syndrome (CRS) involves a bidirectional relationship where dysfunction in one organ exacerbates the other. A key factor in this interaction is the impact of right ventricular (RV) volume overload on renal blood flow, which is vital for the progression and management of heart failure (HF).

Objective: This study aims to explore and quantify the relationship between right ventricular volume overload, i.e, echocardiographic assessments of right ventricular diameter (RVD), and the time-to-peak (TTP) of renal blood flow in patients with HF measured by 99mTc-DTPA renal scintigraphy.

Methods: This single-center study included 304 stable, ambulatory HF patients admitted between October 2017 and August 2022. HF was diagnosed based on the 2016 ESC guidelines. Echocardiographic parameters, including RVD, and TTP of renal blood flow measured by 99mTc-DTPA renal scintigraphy, were collected. Statistical analysis was conducted using SPSS and R software, with Spearman correlation analysis used to assess the relationship between echocardiographic parameters and TTP.

Results: The study showed there was a significant correlation between RVD and TTP (rs=0.535, P<0.001), indicating that RV volume overload is closely related to impaired renal perfusion. The median TTP among the study population was 27.25 seconds (IQR: 21-39 seconds). Corrected for body surface area (BSA), RVD was found to be significantly higher in patients with heart failure with reduced ejection fraction (HFrEF) compared to heart failure with preserved ejection fraction (HFpEF) and heart failure with mid-range ejection fraction (HFmrEF) (HFrEF: 20.62 mm/m², HFmrEF: 18.72 mm/m², HFpEF: 18.09 mm/m²; p < 0.001). Furthermore, right atrial diameter (RAD) corrected for BSA (RAD/BSA) demonstrated the strongest correlation with TTP in the HFrEF subgroup (rs=0.602, p<0.001).
Conclusions: Our findings highlight the significant impact of right ventricular volume overload on renal perfusion, providing valuable insights into the pathophysiology of CRS. These results suggest that therapeutic strategies aimed at reducing RV overload could enhance renal perfusion and improve overall outcomes in HF patients.