Intrarenal Flow Alterations During Transition From Euvolemia to Intravascular Volume Expansion in Heart Failure Patients.

OBJECTIVES

The goal of this study was to assess: 1) the intrarenal flow in heart failure (HF) patients during the transition from euvolemia to intravascular volume overload; and 2) the relationship between intrarenal flow and diuretic efficiency.

BACKGROUND

Intrarenal blood flow alterations may help to better understand impaired volume handling in HF.

METHODS

Resistance index (RI) and venous impedance index (VII) were assessed in 6 healthy subjects, 40 euvolemic HF patients with reduced ejection fraction (HFrEF), and 10 HF patients with preserved ejection fraction (HFpEF). Assessments were performed by using Doppler ultrasonography at baseline, during 3 h of intravascular volume expansion with 1 l of hydroxyethyl starch 6%, and 1 h after the administration of a loop diuretic. Clinical parameters, echocardiography, and biochemistry were assessed. Urine output was collected after 3 and 24 h.

RESULTS

In response to volume expansion, VII increased significantly in HFrEF patients (0.4 ± 0.3 to 0.7 ± 0.2; p < 0.001) and in HFpEF patients (0.4 ± 0.3 to 0.7 ± 0.2; p = 0.002) but not in healthy subjects (0.2 ± 0.2 to 0.3 ± 0.1; p = 0.622). This outcome was reversed after loop diuretic administration. In contrast, RI did not change significantly after volume expansion. Echocardiographic-estimated filling pressures did not change significantly. VII during volume expansion was significantly correlated with diuretic response in HF patients independent of baseline renal function (R2 = 0.35; p < 0.001).

CONCLUSIONS

In HF patients, intravascular volume expansion resulted in significant blunting of venous flow before a significant increase in cardiac filling pressures could be demonstrated. The observed impaired renal venous flow is correlated with less diuretic efficiency. Intrarenal venous flow patterns may be of interest for evaluating renal congestion.