Decreased cardiac output, venous congestion and the association with renal impairment in patients with cardiac dysfunction.

BACKGROUND: Renal failure in heart failure is related to decreased cardiac output. However, little is known about its association with venous congestion. AIMS: To investigate the relationship between venous congestion and glomerular filtration rate (GFR) in patients with cardiac dysfunction. METHODS AND
RESULTS: Right atrial pressure (RAP) and cardiac index (CI) were determined by right heart catheterisation in 51 patients with cardiac dysfunction, secondary to pulmonary hypertension. GFR and renal blood flow (RBF) were measured as (125)I-Iothalamate and (131)I-Hippuran clearances, respectively. Mean age was 40+/-11 years and 69% of patients were female. GFR was 73+/-19 ml/min/1.73 m2 with a CI of 2.1+/-0.7 l/min/m2. In multivariate analysis, RBF (r=0.664, p<0.001) and RAP (r=- 0.367, p=0.020) were independently associated with GFR. In patients in the lower ranges of RBF, venous congestion was an important determinant of renal function.
CONCLUSION: RBF is the main factor determining GFR in patients with cardiac dysfunction. Venous congestion, characterised by an increased RAP, adjusted for RBF is also related to GFR. Treatment to preserve GFR should not only focus on improvement of renal perfusion, but also on decreasing venous congestion.