Endocarditis Murmur Quiz

Understanding Endocarditis Murmurs: A Practice Guide

Infective endocarditis (IE) is a serious infection of the heart’s endocardial surface, most commonly affecting the valves. The resulting vegetations can cause significant valvular damage, leading to regurgitation and the development of new or changing heart murmurs. Correctly identifying these murmurs is a critical clinical skill.

Mitral Regurgitation (MR) in Endocarditis

When IE affects the mitral valve, it can cause leaflet perforation or rupture of the chordae tendineae. This leads to acute MR, characterized by a holosystolic (pansystolic) murmur heard best at the apex. This murmur classically radiates to the axilla.

Aortic Regurgitation (AR) in Endocarditis

Destruction of the aortic valve leaflets by infection prevents proper closure during diastole. This results in aortic regurgitation, which presents as a high-pitched, blowing, early diastolic decrescendo murmur. It is typically best heard at the left sternal border.

Tricuspid Regurgitation (TR) in Right-Sided Endocarditis

Right-sided IE is most common in persons who inject drugs. The tricuspid valve is the most frequently affected site. The resulting TR produces a holosystolic murmur at the left lower sternal border that famously increases in intensity with inspiration (Carvallo’s sign).

Dynamic Maneuvers: Carvallo’s Sign

Dynamic maneuvers are key to differentiating right-sided from left-sided murmurs. Inspiration increases venous return to the right side of the heart. This increased blood flow across the tricuspid and pulmonic valves will accentuate right-sided murmurs, a finding known as Carvallo’s sign for tricuspid regurgitation.

Hallmarks of Left-Sided Endocarditis Murmurs

• Location: Apex for mitral valve; left/right upper sternal border for aortic.
• Radiation: Mitral regurgitation radiates to the axilla.
• Timing: Holosystolic for MR; early diastolic for AR.
• Maneuvers: Generally do not increase with inspiration.
• Complications: Can lead to severe pulmonary edema and heart failure.

Characteristics of Right-Sided Endocarditis Murmurs

• Classic Patient: History of intravenous drug use.
• Valve: Tricuspid valve is most commonly affected.
• Murmur: Holosystolic murmur of tricuspid regurgitation.
• Location: Best heard at the left lower sternal border.
• Key Sign: Murmur intensity increases with inspiration (Carvallo’s sign).

Complications: Perivalvular Abscess and Heart Block

The aortic valve’s close proximity to the heart’s conduction system is a critical anatomical relationship. A perivalvular abscess extending from the aortic ring can invade the atrioventricular (AV) node, causing new-onset heart block. This is a severe complication requiring immediate attention.

Culture-Negative Endocarditis Considerations

When blood cultures are negative but clinical suspicion for IE is high, consider fastidious organisms. Coxiella burnetii (Q fever) is a classic cause, often presenting with large vegetations and significant aortic regurgitation. This highlights the importance of a thorough exposure history.

Nonbacterial Thrombotic Endocarditis (NBTE)

NBTE involves sterile vegetations, often in the context of malignancy or hypercoagulable states. Because these vegetations are typically non-inflammatory and less destructive, they often produce only a faint murmur or no murmur at all, despite being a high risk for systemic embolization.

Key Takeaways

• Mitral Regurgitation: Holosystolic murmur at the apex, radiating to the axilla.
• Aortic Regurgitation: High-pitched, blowing, early diastolic murmur at the left sternal border.
• Tricuspid Regurgitation: Holosystolic murmur at the left lower sternal border, louder with inspiration.
• Changing Murmur: A red flag for acute, severe valvular destruction.
• New Heart Block: Suggests an aortic root abscess invading the conduction system.

This content provides an overview of key auscultatory findings in infective endocarditis for educational purposes. It is not intended as medical advice. Understanding the pathophysiology of endocarditis-related murmurs, including mitral, aortic, and tricuspid regurgitation, is essential for clinical practice and board examinations.