From the Guidelines
Heart failure can cause acute kidney injury (AKI) through several interconnected mechanisms, including decreased renal perfusion, activation of the renin-angiotensin-aldosterone system (RAAS), and sympathetic nervous system, as well as the use of medications such as diuretics, which can worsen kidney function 1. When the heart fails to pump effectively, it reduces cardiac output and blood pressure, leading to decreased renal perfusion. This reduction in blood flow to the kidneys triggers compensatory mechanisms, including activation of the RAAS and sympathetic nervous system, which initially aim to maintain blood pressure but ultimately can worsen kidney function. The decreased forward flow also causes venous congestion, increasing pressure in the renal veins and further impairing kidney filtration. Additionally, heart failure creates a neurohormonal environment with elevated levels of inflammatory cytokines and oxidative stress that directly damage kidney tissue. Medications used to treat heart failure, such as diuretics, ACE inhibitors, and ARBs, can sometimes worsen kidney function, especially if dosing isn't carefully managed, as noted in a study on renal function monitoring in heart failure 1. This cardiorenal syndrome represents a vicious cycle where heart dysfunction worsens kidney function, which in turn can further compromise cardiac output through fluid overload, electrolyte disturbances, and uremic toxins that depress myocardial function. Key management issues include the potential for renal dysfunction to limit the use of renin–angiotensin–aldosterone system blockers and the need for careful monitoring and potentially joint care with a nephrologist in cases of acute worsening of renal function, as outlined in guidelines for the diagnosis and treatment of acute and chronic heart failure 1. The importance of monitoring renal function in patients with heart failure is also highlighted by the association between even mild-to-moderate impairment in renal function and a worse prognosis, as discussed in guidelines on the diagnosis and treatment of acute heart failure 1. Some key points to consider in the management of heart failure and AKI include:
- Careful monitoring of renal function and adjustment of medications as needed
- Avoidance of nephrotoxic agents and careful use of diuretics
- Consideration of joint care with a nephrologist in complex cases
- Recognition of the potential for cardiorenal syndrome and its implications for patient management.
From the Research
Mechanisms of Acute Kidney Injury in Heart Failure
- Heart failure can cause Acute Kidney Injury (AKI) due to various mechanisms, including renal venous congestion, decreased renal perfusion, and increased venous pressure 2.
- The cardiorenal syndrome (CRS) is a well-known condition where the heart and kidney interact, leading to acute or chronic kidney disease 2.
- In patients with acute heart failure, AKI is common and can be caused by factors such as volume overload, metabolic acidosis, and electrolyte disorders 2.
Role of Therapeutic Decisions in AKI Development
- Therapeutic decisions, such as the use of diuretics, angiotensin-converting enzyme inhibitors (ACE-Is), and angiotensin receptor blockers (ARBs), can impact the development of AKI in patients with heart failure 3, 4.
- The discontinuation or dose reduction of ACE-Is/ARBs may improve renal outcome, but can also lead to less efficient decongestion 3.
- Diuretics can cause a rise in serum creatinine and AKI, but decongestion therapy can improve survival and prevent hospital admissions in the long term 5.
Predictors and Outcomes of AKI in Heart Failure
- The incidence of AKI in patients with heart failure is approximately 33%, and the risk of dying in the hospital is tripled 6.
- Predictors of AKI in heart failure patients include diabetes, hypertension, history of chronic kidney disease, and age 6.
- Mortality remains high at 1-year follow-up after the onset of AKI, emphasizing the need for early intervention and treatment 6.