Definition and Clinical Relevance

A bruit is an abnormal auscultatory sound produced by turbulent blood flow within an artery or arteriovenous structure, often due to stenosis, aneurysm, or arteriovenous malformation (AVM). It is typically heard as a swishing or whooshing sound, which may be systolic, continuous, or occasionally contain a diastolic component. Loud bruits may be accompanied by a palpable thrill, but a thrill alone is not a definitive marker of severity or specific pathology.

Bruits are clinically significant when detected over major vascular territories such as the:

• Carotid arteries

• Abdominal aorta

• Renal arteries

• Subclavian, femoral, and popliteal arteries

• Thyroid gland

Persistent bruits that are present regardless of patient positioning or are audible during diastole warrant urgent evaluation due to their potential association with serious vascular pathology.

Assessment and Examination

Auscultation Technique

• Use the bell of the stethoscope to enhance low-frequency sounds.

• Apply minimal pressure to avoid artificially inducing turbulence.

• Auscultate before palpating the vessel to avoid altering hemodynamics or risking embolization, especially over the carotid arteries.

• For challenging areas (e.g., popliteal fossa), position the patient supine with the limb slightly elevated.

Systematic examination of key sites

1. Abdominal Aorta

   • Auscultate at the epigastrium.

   • A midline systolic bruit in conjunction with a pulsatile mass suggests an abdominal aortic aneurysm (AAA).

   • Look for signs of dissection or rupture:

     • Tearing back or abdominal pain

     • Hypotension

     • Grey-Turner or Cullen’s signs (flank/periumbilical ecchymosis)

2. Carotid Arteries

   • Auscultate near the angle of the jaw.

   • A systolic bruit suggests carotid stenosis, a risk factor for TIA or stroke.

   • Never palpate both carotids simultaneously.

3. Renal Arteries

   • Bruits lateralized to the flanks may suggest renal artery stenosis, especially in:

     • Refractory hypertension

     • Young patients with new-onset hypertension

     • Unexplained renal dysfunction

4. Peripheral Arteries (Femoral, Popliteal, Subclavian)

   • Bruits here may indicate peripheral arterial disease (PAD).

   • Evaluate for:

     • Claudication

     • Diminished distal pulses

     • Cold or pale limbs

     • Non-healing ulcers

5. Thyroid Gland

   • A systolic bruit over an enlarged thyroid may indicate thyrotoxicosis or thyroid storm.

   • Accompanying signs include tremor, palpitations, and weight loss.

Associated clinical findings and emergencies

Red Flags by Location

• AAA Dissection/Rupture:

  • Sudden tearing pain (abdomen/back)

  • Syncope, hypotension, altered mental status

  • Cullen's or Grey-Turner sign

• Carotid Stenosis/TIA:

  • Transient symptoms: aphasia, hemiparesis, diplopia, vertigo

  • May precede major stroke

• Renal Artery Stenosis:

  • Sudden, severe, or drug-resistant hypertension

  • Lateralized bruit and reduced kidney function

• Peripheral Arterial Disease (PAD):

  • Intermittent claudication

  • Weak or absent distal pulses

  • Non-healing ulcers, cold limbs

• Thyroid Storm:

  • Fever, agitation, tachyarrhythmia

  • Tremor, hepatomegaly, altered LOC

Differential diagnoses and key features

Diagnostic evaluation

Laboratory tests

• CBC: To assess for anemia

• Renal Panel: Creatinine, BUN (for renal artery stenosis)

• Thyroid Function: TSH, free T4 (for thyrotoxicosis)

• ESR, CRP: Rule out vasculitis or inflammatory causes

Imaging modalities

• Duplex Doppler Ultrasound: First-line for carotid, renal, and peripheral arteries

• CT Angiography (CTA) or MR Angiography (MRA): For aneurysms, dissections, or vascular anomalies

• Echocardiography: For high-output states or embolic sources

• Conventional Angiography: Gold standard for pre-surgical vascular assessment

• POCUS: Rapid bedside evaluation of AAA and peripheral flow

Management Strategies

Medical management

• Antiplatelets (e.g., aspirin): Carotid stenosis, PAD

• Antihypertensives: Especially in renal artery stenosis, AAA risk

• Thyroid suppression and beta-blockers: For thyrotoxicosis or thyroid storm

• Statins, smoking cessation, exercise: Atherosclerosis control

Interventional/surgical options

• Carotid Endarterectomy or Stenting: For high-grade carotid stenosis

• Aneurysm Repair: Endovascular or open AAA repair

• Balloon Angioplasty with or without Stenting: For renal or peripheral artery stenosis

• AV Fistula Ligation: If symptomatic or high-output failure

Pediatric and geriatric Considerations

Pediatric

• Innocent bruits (e.g., cervical or supraclavicular) are common.

• Important to distinguish from congenital vascular anomalies (e.g., AVMs, coarctation murmurs).

• Auscultate over port-wine stains or hemangiomas to detect underlying vascular connections.

Geriatric

• Higher prevalence of atherosclerotic bruits.

• Bruits in multiple regions (e.g., carotid, femoral) warrant a thorough cardiovascular risk assessment.

• Monitor closely for evolving ischemic or neurologic symptoms.

Patient education and counseling

• Explain the significance of a bruit and the need for follow-up.

• Reinforce medication adherence and lifestyle changes (diet, exercise, smoking cessation).

• Educate on stroke warning signs using the FAST mnemonic:

  • Face drooping

  • Arm weakness

  • Speech difficulty

  • Time to call emergency services

• Encourage routine vascular screening in high-risk patients (e.g., diabetics, hypertensives, smokers).

References

1. Amarenco P, Labreuche J, Mazighi M. Lessons from carotid endarterectomy and stenting trials. Lancet. 2010;376(9746):1028–1031.

2. Brott TG, Hobson RW II, Howard G, et al. Stenting versus endarterectomy for treatment of carotid-artery stenosis. N Engl J Med. 2010;363(1):11–23.

3. Hirsch AT, Haskal ZJ, Hertzer NR, et al. ACC/AHA 2005 practice guidelines for the management of patients with peripheral arterial disease. J Am Coll Cardiol. 2006;47(6):1239–1312.

4. Wilterdink JL, Easton JD. Vascular event risk after transient ischemic attack. Arch Neurol. 1992;49(9):982–985.

5. Biller J, Feinberg WM, Castaldo JE, et al. Guidelines for carotid endarterectomy. Stroke. 1998;29(2):554–562.

6. O’Connor RE, Slovis CM, Hunt RC, et al. American Heart Association/American Stroke Association Expert Consensus on the recognition and management of stroke in the emergency department. Circulation. 2013;127(13):e393–e461.