Bruit vs. Murmur: Distinguishing Vascular Sounds from Cardiac Murmurs

When physicians use a stethoscope during a physical exam, they listen for a variety of sounds produced by the body. Two common categories of “whooshing” or “swishing” noises are bruits and murmurs. Though they may sound similar to the untrained ear, they stem from different anatomical sources and can signify distinct conditions. Understanding whether a patient has a vascular (bruit) or cardiac (murmur) origin to these sounds is key to an accurate diagnosis and treatment plan.

In this article, we will clarify the core differences between bruits and murmurs—covering how each arises, why clinicians listen for them, and what their detection can reveal about a patient’s health.

1. Defining Bruits and Murmurs

What Are Bruits?

A bruit (pronounced “brew-ee”) is an abnormal sound—often described as a “whooshing” or “swishing” noise—heard over an artery. It generally indicates turbulent blood flow, most frequently due to a partial obstruction or narrowing within the vessel. Since the blood vessels themselves don’t normally produce audible sounds, the presence of a bruit typically suggests an underlying vascular issue that warrants further evaluation.

• Common Sites: Carotid arteries (in the neck), femoral arteries (in the groin), and the abdominal aorta (in the abdomen).
• Mechanism: Blood flow that becomes turbulent due to plaque buildup (atherosclerosis) or other forms of stenosis (narrowing) can create vibrations in the artery walls. These vibrations are what clinicians can pick up during auscultation.

What Are Heart Murmurs?

A heart murmur is an extra or unusual sound produced by blood flow within the heart or near its valves. Murmurs can range from faint and barely audible to very pronounced and even palpable (felt as a vibration on the chest wall, known as a thrill). Unlike bruits, which occur in arteries, murmurs specifically relate to blood flowing through or near the heart chambers and valves.

• Common Causes: Valve abnormalities (e.g., stenosis or regurgitation), congenital heart defects, or increased blood flow across normal cardiac structures (innocent murmurs).
• Timing: Heart murmurs are described by when they occur in the cardiac cycle—systolic murmurs (between the first and second heart sounds, S1 and S2) or diastolic murmurs (after S2 and before the next S1).

2. Vascular vs. Cardiac Origins: Why They Occur 

The Source of a Bruit

1. Arterial Narrowing (Stenosis)
   • The most common cause of a bruit is atherosclerosis, where plaque accumulates in the artery’s walls, narrowing its internal diameter.
   • Other causes include external compression by tumors, aneurysms, or congenital anomalies.
2. Turbulent Flow
   • Normally, blood flows smoothly in a laminar pattern through healthy vessels. When a vessel narrows, the velocity of blood flow increases, creating eddies or turbulence that produce a whooshing sound.
3. Clinical Significance
   • Bruits often signal early or advanced vascular disease, such as carotid artery stenosis, which can predispose individuals to stroke.
   • Detecting a bruit during an exam prompts further testing, like an ultrasound or angiography, to quantify the narrowing and decide on possible interventions.

The Source of a Murmur

1. Valve Abnormalities
   • Heart valves that are stiff or narrowed (stenosis) or leaky (regurgitation) can cause blood to rush through small openings or backflow into a chamber, producing turbulent flow in the heart.
2. Structural Variations
   • Congenital heart defects like atrial septal defects (ASD) or ventricular septal defects (VSD) can also create murmurs due to abnormal blood flow patterns.
3. High Output States
   • Even if the valves are normal, conditions such as hyperthyroidism or anemia can increase blood flow to the point where it becomes turbulent, resulting in what’s known as an “innocent” or “functional” murmur. 

3. How Clinicians Differentiate Bruits from Murmurs

Location of Auscultation

1. Bruit
   • Listened for over the artery itself—commonly in the neck (carotid bruit), groin (femoral bruit), or abdomen (abdominal aorta bruit).
   • The stethoscope is positioned away from the heart, focusing instead on main arteries in the body.
2. Murmur
   • Detected at specific locations on the chest wall that correspond to particular heart valves (e.g., the aortic, pulmonic, tricuspid, and mitral areas).
   • Timing and character of the murmur (systolic vs. diastolic, crescendo vs. decrescendo) provide further clues. 

Sound Quality and Timing

1. Bruit
   • Typically described as a swishing or blowing sound heard during systole (sometimes throughout both systole and diastole, depending on the severity of stenosis).
   • Because bruits are linked to vascular flow, they do not follow the “lub-dub” heart cycle in the same way a murmur would, though they often peak during the systolic phase when arterial pressure is highest.
2. Murmur
   • Can be systolic, diastolic, or continuous, and the timing is strictly related to the cardiac cycle.
   • Murmurs often have descriptive terms like “harsh,” “blowing,” “rumbling,” or “musical,” depending on the pathology.

4. Significance and Health Implications

Bruits: Early Alerts in Vascular Health

• Atherosclerosis Warning: The detection of a vascular sound in the neck (carotid bruit) can indicate a significant plaque buildup. This is an important risk factor for stroke.
• Peripheral Artery Disease (PAD): A bruit in the femoral region might hint at PAD, which can lead to leg pain (claudication) and higher cardiovascular risk.
• Abdominal Aortic Aneurysm (AAA): A bruit in the abdomen can reveal an aneurysm or stenosis in arteries branching off the aorta.

Early detection of bruits allows for interventions—such as medication adjustments, surgical procedures (e.g., carotid endarterectomy), or stenting—to reduce the risk of severe complications like stroke or vascular insufficiency.

Murmurs: Detecting Cardiac Abnormalities

• Valve Disease: Murmurs may prompt an evaluation for conditions like aortic stenosis or mitral regurgitation. Left untreated, these valve issues can result in arrhythmias, heart failure, or other forms of cardiac compromise.
• Congenital Heart Defects: Identifying a murmur in infancy can lead to early surgical correction or medical management of structural defects, significantly improving quality of life and prognosis.
• Functional and Innocent Murmurs: Some murmurs are benign and do not require any treatment; however, correct identification and monitoring ensure they don’t mask underlying problems. 

5. When to Seek Further Evaluation

Bruits

1. Age & Risk Factors: Middle-aged or older adults, especially those with hypertension, high cholesterol, diabetes, or a history of smoking, should be evaluated if a bruit is detected.
2. Immediate Testing: A carotid ultrasound or CT angiography may follow the discovery of a bruit to assess the degree of arterial narrowing.
3. Symptomatic Cases: Patients reporting dizziness, transient ischemic attacks (TIAs), or changes in vision alongside a bruit should be quickly referred for vascular imaging.

Murmurs

1. Symptom Profile: Shortness of breath, chest pain, or signs of heart failure accompanying a murmur typically prompt an echocardiogram (ultrasound of the heart).
2. New Onset Murmur: A newly detected murmur in adulthood warrants evaluation to rule out progressive valve disease or underlying structural issues.
3. Pediatric Considerations: Many murmurs in children are innocent, but some are pathological. Pediatric cardiology evaluation is crucial in unclear cases.

6. Managing Bruits and Murmurs

Addressing Bruits (Vascular Sounds)

• Lifestyle Modifications: Quitting smoking, managing cholesterol levels, and controlling blood pressure can slow or reverse arterial damage.
• Medications: Antiplatelet agents, statins, and antihypertensives can help stabilize plaque and reduce the risk of vascular events.
• Interventional Procedures: Carotid endarterectomy or angioplasty may be recommended for severe stenosis to improve blood flow and reduce stroke risk.

Addressing Heart Murmurs (Abnormal Heart Sounds)

• Medical Therapy: Depending on the underlying cause—like valve regurgitation—diuretics, beta-blockers, or ACE inhibitors may be used to control symptoms and reduce cardiac workload.
• Surgical Intervention: Valve repair or replacement may be necessary for significant valve stenosis or regurgitation.
• Ongoing Monitoring: Regular follow-up with echocardiograms ensures early detection of any changes in valve function or cardiac structure.

7. Key Takeaways: Vascular vs. Cardiac

1. Source
   • Bruit: Arteries outside the heart (vascular).
   • Murmur: Heart valves and chambers (cardiac).
2. Primary Cause
   • Bruit: Turbulent flow due to artery narrowing or abnormal vessel structure.
   • Murmur: Turbulent flow due to valve issues, structural defects, or high-output states within the heart.
3. Clinical Significance
   • Bruit: Often points to atherosclerosis or other vascular disease; can be an early warning sign of stroke risk (e.g., carotid bruit).
   • Murmur: Can indicate valve disorders, congenital defects, or other forms of abnormal heart sounds warranting further cardiac evaluation.
4. Detection
   • Bruit: Auscultation over the neck, abdomen, or groin arteries.
   • Murmur: Auscultation over the chest wall, near corresponding heart valves.

8. Conclusion

Bruits and murmurs both produce whooshing sounds that signal some form of turbulent blood flow. However, their origins differ significantly—bruits come from major arteries (vascular), while murmurs emanate from within the heart (cardiac). Recognizing whether a sound is vascular or cardiac is essential for accurate diagnosis and timely intervention. Bruits can herald serious conditions like carotid artery stenosis or peripheral arterial disease, whereas murmurs can reveal valvular dysfunction or congenital defects.

By paying close attention to the location, timing, and character of these extra sounds, healthcare professionals can identify potential cardiovascular risks, initiate further diagnostic testing, and tailor the appropriate treatment strategy. Early detection and management of both vascular and cardiac abnormalities can dramatically improve patient outcomes and overall cardiovascular health.