What is cardiorenal syndrome (CRS), a condition characterized by impaired renal function and cardiovascular disease?

Medical Advisory BoardAll articles are reviewed for accuracy by our Medical Advisory Board
Article Review Status
Submitted
Under Review
Approved

Last updated: May 1, 2025 • View editorial policy

From the Guidelines

Cardiorenal syndrome is a complex medical condition characterized by the simultaneous dysfunction of both the heart and kidneys, where the failure of one organ accelerates the failure of the other, as described in the 2018 narrative review 1. This bidirectional relationship creates a harmful cycle that worsens patient outcomes.

Key Characteristics

  • The condition develops because the heart and kidneys are interconnected through hemodynamic, neurohormonal, and inflammatory pathways, with dysfunction in one organ inevitably affecting the other through altered blood flow, increased venous pressure, and activation of harmful compensatory mechanisms.
  • There are five types of cardiorenal syndrome:
    • Type 1 (acute heart failure causing acute kidney injury)
    • Type 2 (chronic heart failure leading to progressive kidney disease)
    • Type 3 (acute kidney injury causing heart dysfunction)
    • Type 4 (chronic kidney disease contributing to heart failure)
    • Type 5 (systemic conditions affecting both organs simultaneously), as outlined in the study 1.

Management Considerations

Management typically involves treating the underlying cause while carefully balancing medications that affect both systems, as noted in the European Heart Journal study 2.

  • Diuretics like furosemide are commonly used but require careful dosing to avoid worsening kidney function.
  • ACE inhibitors or ARBs may be prescribed at low doses with gradual titration.
  • Fluid restriction (typically 1.5-2 liters daily), sodium limitation, and daily weight monitoring are essential components of management. The European Society of Cardiology guidelines also highlight the importance of monitoring renal function in patients with heart failure, as certain medications like renin–angiotensin–aldosterone blockers can cause a fall in GFR 2.

From the Research

Definition of Cardiorenal Syndrome

  • Cardiorenal syndrome (CRS) is defined as a complex pathophysiological disorder of the heart and the kidneys in which acute or chronic dysfunction in one organ may induce acute or chronic dysfunction in the other organ 3, 4, 5.
  • This syndrome is characterized by a vicious cycle where dysfunction in either the heart or kidneys exacerbates the loss of function in the other organ 4.

Classification of Cardiorenal Syndrome

  • CRS is classified into five subtypes based on the primary organ dysfunction (heart or kidney) and whether the organ dysfunction is acute or chronic 3, 4, 5.
  • The five subtypes are: + Type 1: acute cardiorenal syndrome, where an acute deterioration in cardiac function leads to acute kidney injury (AKI) 3, 4, 5. + Type 2: chronic cardiorenal syndrome, where chronic abnormalities in heart function lead to kidney injury or dysfunction 4, 5. + Type 3: acute renocardiac syndrome, where AKI leads to acute cardiac injury and/or dysfunction 3, 4, 5. + Type 4: chronic renocardiac syndrome, where chronic kidney disease leads to heart injury, disease, and/or dysfunction 4, 5. + Type 5: systemic conditions leading to simultaneous injury and/or dysfunction of the heart and kidney 4, 5.

Pathophysiology and Epidemiology

  • The pathophysiology of CRS involves a complex interplay between the heart and kidneys, with dysfunction in one organ affecting the other 3, 6.
  • The epidemiology of CRS is not well understood, but it is recognized as a major clinical problem in patients with heart failure and kidney disease 6.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

The cardiorenal syndrome.

Blood purification, 2009

Research

Cardiorenal Syndrome.

Critical care clinics, 2021

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.