Cardiorenal Syndrome

Key Features

• Defined as a pathophysiologic disorder of the heart and kidneys wherein the acute or chronic deterioration of one organ results in the acute or chronic deterioration of the other

• Classified into five types

  • Type 1 consists of acute kidney injury (AKI) stemming from acute cardiac disease

  • Type 2 is chronic kidney disease (CKD) due to chronic cardiac disease

  • Type 3 is acute cardiac disease as a result of AKI

  • Type 4 is chronic cardiac decompensation from CKD

  • Type 5 consists of heart and kidney dysfunction due to other acute or chronic systemic disorders (such as sepsis)

Clinical Findings

• Cardiac dysfunction: acute or chronic heart failure, ischemic injury, or arrhythmias

• Kidney disease: acute or chronic, depending on the type of cardiorenal syndrome

Diagnosis

• Evaluate cardiac status with applicable studies, such as BNP, ECG, and echocardiogram

• Evaluate kidney status with applicable studies, such as

  • BUN; serum creatinine, serum electrolytes, serum bicarbonate

  • Complete blood count

  • Urine microscopy

  • Fractional excretion of sodium or FE_Na = (urine_Na/serum_Na)/(urine_Cr/serum_Cr) × 100%

  • FE_Na is high (> 1%) in acute tubular necrosis

  • Renal ultrasound

Treatment

• Treat primary underlying cardiac or renal dysfunction