Cardiorenal syndrome in heart failure: a cardiologist's perspective

One of the most important comorbidities in heart failure is renal dysfunction. Diminished estimated glomerular filtration rate is a potent predictor of cardiovascular mortality and complications. On the other hand, worsening heart failure or acute decompensated heart failure can accelerate worsening of renal function--the so-called cardiorenal syndrome. Risk factors include hypertension, diabetes, elderly age, and prior history of heart or renal failure. The pathophysiology of the cardiorenal syndrome involves intrarenal hemodynamics, transrenal perfusion pressure and systemic neurohormonal factors. Clinical management of the patient with cardiorenal syndrome includes the challenge of diuretic resistance, which may involve correcting the underlying cause, combination diuretics or diuretic infusions. The key to improved outcome is the optimization of proven heart failure therapies. The use of vasodilator therapy is the current mainstay of treatment. Nesiritide, or recombinant B-type natriuretic peptide, has courted controversy regarding its role in cardiorenal syndrome. However, data are emerging that low doses appear to be renal-protective. Other more recent strategies include ultrafiltration, vasopressin antagonists and adenosine antagonists. All of these newer modalities promise more rapid volume removal, but their ultimate impact on survival or preservation of renal function is unknown at the present time. Because of the complex nature of these patients, and the compromised outcome, it is important that cardiologists, nephrologists and internists all work together toward the common goal of protecting the patient with cardiorenal syndrome, and use the best available evidence for management.