What is the relationship between lactic acidosis and high-output heart failure (HF)?

From the Guidelines

Lactic acidosis in high output heart failure is a critical condition that requires immediate attention to address the underlying cause and optimize tissue perfusion, as evidenced by the European Society of Cardiology guidelines 1. The management of lactic acidosis in high output heart failure involves a multifaceted approach, including:

• Administering intravenous fluids cautiously to improve perfusion without worsening cardiac congestion
• Using vasopressors like norepinephrine if needed to support blood pressure
• Providing oxygen supplementation to maintain saturation above 94%
• Implementing specific treatments based on the etiology of high output failure, such as beta-blockers for thyrotoxicosis, antibiotics for sepsis, or phlebotomy for severe anemia The pathophysiology of lactic acidosis in high output heart failure is characterized by tissue hypoxia despite increased cardiac output, resulting in anaerobic metabolism and lactate accumulation, as described in the ESC guidelines 1. Key considerations in the management of lactic acidosis in high output heart failure include:
• Regular monitoring of lactate levels, arterial blood gases, and hemodynamic parameters
• Continuous renal replacement therapy may be necessary for severe acidosis unresponsive to other measures
• Addressing the underlying cause of high output failure, such as anaemia, thyrotoxicosis, or sepsis, is crucial to improving outcomes, as highlighted in the ESC guidelines 1.

From the Research

Lactic Acidosis in High Output Heart Failure

• Lactic acidosis is a condition characterized by the accumulation of lactate in the blood, which can occur in various clinical settings, including high output heart failure 2.
• High output heart failure is a condition where the heart pumps more blood than normal, but still fails to meet the body's needs, leading to symptoms such as shortness of breath and fatigue.
• Lactic acidosis can occur in high output heart failure due to various mechanisms, including tissue hypoxia and epinephrine-induced stimulation of aerobic glycolysis 3.

Prevalence of Lactic Acidosis in Heart Failure

• The prevalence of lactic acidosis in patients with advanced heart failure is significant, with one study reporting a prevalence of 25% in patients with stage D heart failure 4.
• Another study found that hyperlactataemia (>2 mmol/L) was present in 38.0% of normotensive patients with acute heart failure 5.
• The presence of lactic acidosis is associated with increased mortality and poor outcomes in patients with heart failure 5, 6.

Relationship between Lactic Acidosis and Hemodynamics

• There is a discordance between lactic acidemia and hemodynamics in patients with advanced heart failure, with normal lactic acid levels not excluding the presence of depressed cardiac index 6.
• The relationship between lactic acid levels and hemodynamics is complex, and lactic acid levels do not always correlate with cardiac output or systemic vascular resistance 4, 6.
• Invasive hemodynamics should not be delayed based on normal lactic acid levels alone, as they can provide valuable information on cardiac function and guide treatment decisions 6.