How do you evaluate a cardiac murmur?

From the Guidelines

To evaluate a cardiac murmur, first characterize it by timing, intensity, location, radiation, pitch, and quality, and then proceed with a thorough history, physical examination, electrocardiogram, and echocardiography as the essential diagnostic tool, as recommended by the most recent guidelines 1. The evaluation of a cardiac murmur is a complex process that requires a combination of clinical assessment and diagnostic testing.

• The initial step is to characterize the murmur by its timing (systolic, diastolic, or continuous), intensity (grade 1-6), location, radiation, pitch, and quality.
• A thorough history should be taken, focusing on associated symptoms like chest pain, dyspnea, syncope, or fatigue.
• A complete physical examination should be performed, including vital signs, jugular venous pressure assessment, and careful cardiac auscultation in different positions and with maneuvers like Valsalva or standing.
• An electrocardiogram (ECG) should be ordered to identify rhythm abnormalities or chamber enlargement, as abnormal ECG findings can provide useful information and lead to a more extensive evaluation, including echocardiography 1.
• Echocardiography is essential for definitive evaluation, providing visualization of valvular structure and function, chamber size, and blood flow patterns, and is recommended for patients with diastolic or continuous heart murmurs, apical or left sternal edge holosystolic or late systolic murmurs, and midsystolic murmurs of grade 3 or greater intensity 1. Additional tests may include chest X-ray to assess cardiac silhouette and pulmonary vasculature, and in some cases, cardiac MRI or cardiac catheterization. The evaluation should determine if the murmur is innocent (physiologic) or pathologic, as innocent murmurs are common in children and young adults and require no treatment, whereas pathologic murmurs may require intervention ranging from antibiotic prophylaxis to surgical repair depending on the underlying cause and severity of cardiac dysfunction.
• The classification of murmurs is also important, with holosystolic, midsystolic, early systolic, late systolic, and early diastolic murmurs having different underlying causes and implications for patient management 1. Overall, the evaluation of a cardiac murmur requires a comprehensive approach, incorporating clinical assessment, diagnostic testing, and careful consideration of the underlying cause and severity of the murmur.

From the Research

Evaluation of Cardiac Murmurs

To evaluate a cardiac murmur, several steps can be taken:

• Historical elements that suggest pathology include family history of sudden cardiac death or congenital heart disease, in utero exposure to certain medications or alcohol, maternal diabetes mellitus, history of rheumatic fever or Kawasaki disease, and certain genetic disorders 2
• Physical examination should focus on vital signs, age-appropriate exercise capacity, respiratory or gastrointestinal manifestations of congestive heart failure, and a thorough cardiovascular examination, including features of the murmur, assessment of peripheral perfusion, and auscultation over the heart valves 2
• Red flags that increase the likelihood of a pathologic murmur include a holosystolic or diastolic murmur, grade 3 or higher murmur, harsh quality, an abnormal S2, maximal murmur intensity at the upper left sternal border, a systolic click, or increased intensity when the patient stands 2

Diagnostic Tools

• Electrocardiography and chest radiography rarely assist in the diagnosis of cardiac murmurs 2
• Echocardiography provides a definitive diagnosis and is recommended for evaluation of any potentially pathologic murmur, and for evaluation of neonatal heart murmurs because these are more likely to be manifestations of structural heart disease 2
• In adults with a systolic murmur of unknown cause, a functional murmur can usually be distinguished from an organic murmur, but the ability of the cardiac examination to assess the exact cause of the murmur is limited, especially if more than one lesion is present 3

Approach to Patients with Murmurs

• A thorough cardiac physical examination can identify patients who require further evaluation and management 4
• Diastolic murmurs indicate important underlying valvular pathology requiring further investigation, typically with echocardiography 4
• The proper examination of patients with systolic murmurs, the most common murmurs in clinical practice, is fundamental to cost-effective care 4
• Careful evaluation of the medical history and physical examination are critical in the differentiation of innocent and pathological heart murmurs in children 5

Limitations of Physical Examination

• Physical examination has limitations in diagnosing systolic murmurs, and some classic physical findings are no longer accurate 6
• Physical examination cannot reliably distinguish severe aortic stenosis from less severe stenosis, and classic physical findings, despite having proven value, are absent in many patients with significant cardiac lesions 6
• A simple system using onomatopoeia and classifying systolic murmurs into 1 of 6 patterns is diagnostically helpful 6