Early Diagnosis of Type-2 Cardio-renal Syndrome by Doppler Sonographic Evaluation of Renal Vasoconstriction

Renal failure of type-2 cardio-renal syndrome is due to renal hypoperfusion secondary to heart failure and is mediated by an imbalance between vasoconstrictors and vasodilators. The decrease in glomerular filtration rate does not correlate with left ventricular ejection fraction. Aim of this study was to evaluate, by Doppler sonography, renal hemodynamic alterations in heart failure. Thirty patients (age: 51±15yr) with dilated cardiomyopathy (DCM) and 20 normal subjects (C) were studied. Cardiomyopathy was essential in 36.6%, post-ischemic in 36.6%, alcoholic in 16.7%, post-myocarditis in 10% of patients. All patients were hemodynamically stable. In each patient, echocardiography and renal Doppler sonography (interlobar arterial pulsatility index, PI-K) were performed the same day, together with BUN, creatinine, NT-proBNP measurement. Patients with DCM had normal kidneys morphology and volume. LVEF was 26±6.8%. PI-K was increased compared to C (1.74±0.71 vs 0.95±0.19, p<0.001) and also renal function was impaired (creatinine 128.5±84 vs 70±30 umol/L, p<0.01, BUN 11.6±5.8 vs 7±1.5 mmol/L, p<0.01). Prevalence of renal failure was 36.6% (NYHA 1-2: 23%, NYHA 3-4: 52.9%) while prevalence of increased PI-K was 83.3% (NYHA 1-2: 69.2%, NYHA 3-4: 94.1%). PI-K was increased already in mild heart failure (NYHA 1-2) (PI-K: 1.37±0.3 p<0,01), but more so in patients with more severe heart dysfunction (NYHA 3 e 4) (PI-K: 2,1±0,8 p<0.01) without significant correlation with LVEF or right atrial pressure. There were no differences in creatinine or BUN among patients with different severity of heart dysfunction (creatinine 105±23 vs 140±104 umol/L, urea 10.3±5.7 vs 12.3±6 mmol/L). NT-proBNP was increased in patients with DCM (6249.61±3.963 ng/L) and did not correlate with LVEF, PI-K, renal function, right atrial pressure. In conclusion, in patients with chronic heart failure renal vasoconstriction can be demonstrated by Doppler-sonography in the early stage, when renal function is still normal, and increases with the worsening of heart failure. Renal Doppler resistance indices may be used for early diagnosis of type-2 cardiorenal syndrome and for prevention of acute, diuretic-induced, renal failure. Author Disclosures: D. Sacerdoti: None. S. Gaiani: None. S. Tonello: None. E. Franceschini: None. P. Pesce: None. P. Bizzotto: None. G. Bombonato: None. C. Sarais: None. M. Bolognesi: None. Key Words: Heart failure • Renal circulation • Renal function • Doppler ultrasound