Vascular and Cardiac Sound Differentiation

Definition and Characteristics

A bruit is a sound produced by turbulent blood flow through a narrowed or stenotic blood vessel, representing vascular pathology, according to the American Heart Association 1, 2
Bruits typically have a medium pitched, harsh character and are heard directly over the affected vessel, as described by the American College of Cardiology 1, 3
Radiating heart sounds are cardiac sounds that originate at the heart valves but are transmitted to areas beyond their point of maximum intensity, as noted by the American Heart Association 1, 3

Carotid bruits are important diagnostic signs of potential underlying carotid stenosis, with patients having >50% higher likelihood of harboring hemodynamically significant internal carotid stenosis, according to the American College of Radiology 4, 5
The positive predictive value of carotid bruits for significant stenosis is relatively low (approximately 30%), which increases the importance of radiographic evaluation, as recommended by the American College of Radiology 4, 5
Bruits are associated with increased risk of cardiovascular events, with higher rates of myocardial infarction and cardiovascular death compared to those without bruits, as reported by the American Heart Association 1, 2

Carefully tracing the sound to its point of maximum intensity can help differentiate between bruits and radiating heart sounds, with bruits being loudest directly over the affected vessel, as described by the American College of Cardiology 2
Comparing timing with the cardiac cycle and performing maneuvers that affect blood flow or vessel compression can also aid in differentiation, as recommended by the American Heart Association 1, 3
Advanced diagnostic testing such as duplex ultrasonography may be considered when clinical differentiation is difficult, as suggested by the American College of Cardiology 6

A bruit is often audible in hemodynamically significant arterial stenosis but may be absent in severe, occlusive, or only mildly narrowed vessels, indicating that the presence of a bruit is not a definitive rule‑out for disease. 7
In aortic coarctation, a murmur or bruit can be heard in the left interscapular region, reflecting either the primary narrowing or collateral vessel flow. (ACC/AHA guideline) [7][8]
Continuous murmurs over parasternal areas and around the left scapula are suggestive of collateral vessel development in the setting of a significant proximal obstruction such as aortic coarctation. (ACC/AHA guideline) [7][8]

High‑frequency bruits indicate turbulent flow produced by arterial stenosis and can be distinguished from the normal low‑frequency bruit that contains systolic and diastolic components. (American Journal of Kidney Diseases) 9

The presence or absence of a bruit should never be used as the sole criterion for deciding whether further vascular evaluation is required. (American College of Radiology) 10
Duplex carotid Doppler ultrasonography demonstrates 90 % sensitivity and 94 % specificity for detecting clinically significant stenosis ≥ 70 %, making it the preferred screening modality irrespective of bruit detection. (American College of Radiology) 10
In uncomplicated patients who present with a carotid bruit, the American College of Radiology recommends that ultrasound imaging alone may be sufficient without additional invasive testing. 10
When assessing patients with extremely severe stenosis or multivessel disease, clinicians should be aware that Doppler measurements can either overestimate or underestimate the true severity of the narrowing. (American College of Radiology) 10