The pathophysiology of the chronic cardiorenal syndrome: a magnetic resonance imaging study

To study the association of renal function with renal perfusion and renal parenchymal structure (T-1 relaxation) in patients with chronic heart failure (HF). After IRB approval, 40 participants were enrolled according to HF and renal function status [10 healthy volunteers < 40 years; 10 healthy age-matched volunteers; 10 HF patients eGFR > 60 ml/min/1.73 m(2); 10 HF patients eGFR < 60 ml/min/1.73 m(2)] and assessed by MRI. To be eligible for enrolment all HF patients with renal dysfunction (RD) needed to be diagnosed as having chronic cardiorenal syndrome based on current guidelines. Patients with primary kidney disease were excluded. Renal cortical perfusion correlated with eGFR values (r = 0.52;p < 0.01) and was similar between HF patients with and without RD (p = 0.27). T-1 relaxation correlated negatively with eGFR values (r = -0.41;p > 0.01) and was higher in HF patients compared to volunteers (1121 +/- 102 ms vs. 1054 +/- 65 ms;p = 0.03). T-1 relaxation was selectively prolonged in HF patients with RD (1169 ms +/- 100 vs. HF without RD 1067 ms +/- 79;p = 0.047). In linear regression analyses coronary artery disease (p = 0.01), hypertension (p = 0.04), and diabetes mellitus (p < 0.01) were associated with T-1 relaxation. RD in HF is not primarily mediated by decreased renal perfusion. Instead, chronic reno-parenchymal damage, as indicated by prolonged T-1 relaxation, appears to underly chronic cardiorenal syndrome.