How can heart failure cause Impaired renal function?

From the Guidelines

Heart failure can cause impaired renal function through decreased cardiac output, fluid imbalance, and activation of the renin-angiotensin-aldosterone system (RAAS), leading to kidney damage and dysfunction. This is supported by the most recent and highest quality study, which highlights the importance of optimal management of kidney function in patients with advanced heart failure to improve clinical outcomes and quality of life 1.

Mechanisms of Renal Impairment

The mechanisms by which heart failure impairs renal function include:

• Decreased cardiac output, which reduces blood flow to the kidneys, causing decreased kidney perfusion and oxygen delivery 1
• Activation of the RAAS, which initially tries to compensate by retaining sodium and water, but eventually leads to kidney damage through vasoconstriction and increased pressure in kidney blood vessels 1
• Venous congestion, which causes blood to back up in the veins due to the heart's inability to pump efficiently, increasing pressure in the kidneys and impairing their function
• Use of heart failure medications like diuretics, which can sometimes reduce kidney blood flow further 1

Clinical Implications

The heart-kidney connection, known as cardiorenal syndrome, is a critical aspect of heart failure management, where dysfunction in one organ worsens function in the other, creating a dangerous cycle of deterioration in both organs if not properly managed 1. Regular monitoring of both heart and kidney function, as well as careful medication adjustment, is essential to prevent or mitigate kidney damage and improve patient outcomes.

Key Considerations

Key considerations in the management of patients with heart failure and impaired renal function include:

• Evaluation of kidney dysfunction within the context of clinical trajectories in advanced heart failure 1
• Consideration of advanced heart failure therapies, such as heart-assist devices and kidney transplantation 1
• Recognition of the importance of optimal management of kidney function to improve clinical outcomes and quality of life 1

From the Research

Mechanisms of Impaired Renal Function in Heart Failure

• Heart failure can cause impaired renal function through multiple mechanisms, including fluid overload and increased venous pressure, hypo-perfusion, neurohormonal and inflammatory activation, and concomitant treatment 2.
• Renal dysfunction is common in patients with heart failure and is associated with high morbidity and mortality 2, 3.
• The interaction between cardiac and renal dysfunction may be critical for disease progression and prognosis 2.

Pathophysiology of Cardiorenal Syndrome

• The pathophysiology of cardiorenal syndrome is multifactorial, with reduced renal perfusion and venous congestion being the most important factors 4.
• Renal dysfunction occurs frequently in all phenotypes of heart failure, and when present, it is associated with higher mortality and morbidity 4.
• The kidney and heart are closely related in the clinical syndrome of heart failure, and renal dysfunction can adversely affect cardiac function, causing further clinical deterioration 5.

Clinical Implications of Renal Dysfunction in Heart Failure

• Renal dysfunction is a potential precipitating factor after the first diagnosis of heart failure, and its prevention with new therapies might also improve outcomes 2, 3.
• The evaluation of renal function in patients with heart failure is important as it may reflect their haemodynamic status and provide a better prognostic assessment 2.
• Acute kidney injury is common in patients with acute decompensated heart failure, and worsening renal function is often defined as a rise in serum creatinine of more than 0.3 mg/dL (26.5 µmol/L) 5.
• The relationship between cardiac index and kidney function is complex, and glomerular filtration rate (GFR) becomes dependent on afferent arteriolar flow in the most severe heart failure 6.