Carotid Bruit


Article Author:
Alan Lucerna


Article Editor:
James Espinosa


Editors In Chief:
Casey Ciresi


Managing Editors:
Avais Raja
Orawan Chaigasame
Khalid Alsayouri
Kyle Blair
Radia Jamil
Erin Hughes
Patrick Le
Anoosh Zafar Gondal
Saad Nazir
William Gossman
Hassam Zulfiqar
Navid Mahabadi
Hussain Sajjad
Steve Bhimji
Muhammad Hashmi
John Shell
Matthew Varacallo
Heba Mahdy
Ahmad Malik
Abbey Smiley
Sarosh Vaqar
Mark Pellegrini
James Hughes
Beenish Sohail
Hajira Basit
Phillip Hynes
Sandeep Sekhon


Updated:
10/14/2019 1:32:34 PM

Introduction

A carotid bruit is a vascular sound usually heard with a stethoscope over the carotid artery because of turbulent, non-laminar blood flow through a stenotic area.  A carotid bruit may point to an underlying arterial occlusive pathology that can lead to stroke.[1]  Stroke is a significant cause of morbidity, mortality, and loss of physical mobility.[2] A large portion of ischemic strokes is due to carotid atherosclerotic plaque; therefore, early detection of carotid disease is central to minimizing the incidence of stroke.[3][4]  Since auscultation for a carotid bruit is non-invasive, it has been routinely performed during physical exams, especially in patients deemed high risk for cerebrovascular disease such as the elderly.[5]

Etiology

Atherosclerotic lesions are commonly found in the arteries that arise from the aortic arch vessels. About 80% of these lesions are located at the bifurcation of the common carotid arteries.[1] Carotid artery auscultation is primarily done during an exam to determine if carotid stenosis is present that may predispose the patient to a stroke. In patients with a 2 mm carotid artery luminal narrowing, carotid bruit is present 70% to 89% of the time.[6]

Luminal narrowing of the carotid artery, however, is not the only cause of carotid bruit. Auscultatory sounds from cardiac valvular murmurs that radiate to the neck, cervical venous hums, and intracranial arteriovenous malformations can produce vascular sounds similar to the carotid bruit.[1]

Also, arterial tortuosity and kinking, and high output clinical states may generate bruit even in normal or non-stenotic arteries.  In patients with thyrotoxicosis, for example, there is an increase of five-to ten-fold increase of blood flow to the enlarged thyroid gland resulting in a systolic bruit directly over the gland.[1] A case of bovine-type aortic arch and compression of the kissing carotid arteries by a retrosternal goiter is also a rare cause of a carotid bruit.[7] 

Vascular occlusion from an extrinsic compression such as carotid body tumors and carotid paraganglioma have also been reported to cause carotid bruit.[1][8][9]

Disruption of the blood vessels can cause bruit and have presented in patients having a carotid artery dissection.[10] 

 Reports of carotid bruit from inflammation of the carotid vessel due to inflammatory conditions like Takayasu arteritis are also in the literature.[11]

Non-sclerotic and noninflammatory disease such as fibromuscular dysplasia (FMD) commonly affects the internal carotid arteries and can cause carotid bruit.  These can be found incidentally during the exam.  Cervical FMD is mostly asymptomatic.[12]

Epidemiology

A carotid bruit is a nonspecific finding with a broad sensitivity described in the literature (24-84%).[13]  It is present in about 5% of patients aged 45 to 80 years without clinically significant internal carotid disease.[6]  Only about one-third of patients with carotid bruit are found to have lesions considered hemodynamically significant of 70% to 90% stenosis). In patients with hemodynamically significant carotid narrowing, 50% will be found to have a bruit during carotid auscultation.[3]  A carotid bruit can also present in 20% of healthy children less than 15 years old.  Nearly 22% of patients diagnosed with cervical fibromuscular dysplasia (FMD) are found to have carotid bruits, although patients are seldom found to be symptomatic.[14]

Pathophysiology

The bruit typically implies stenosis at or proximal to the area of auscultation.  The auscultated sound is usually the result of turbulent, non-laminar blood flow through a stenotic area.  The turbulent flow creates vibrations in the arterial wall that then transmits to the body surface where stethoscopic auscultation is possible. Critical stenosis, however, does not occur until the cross-sectional area decreases to 70%, which corresponds to a reduction of lumen diameter by half.  Kurtz previously described the basic science of bruits: “ As stenosis increases, therefore, potential energy ( pressure ) proximal to the stenosis changes to increasing kinetic energy ( velocity ) within the stenosis. With increasing flow velocity, laminar flow through a stenosis eventually changes to turbulent flow, producing vibrations, and a bruit.  Thus, velocity through the stenotic segment and the subsequent character of the bruit depend on the degree of stenosis and the resulting pressure gradient.”  Kurtz further explained that the auscultatory quality and timing of the bruit changes with the degree of stenosis and pressure gradients.  When the lumen is about 50% narrowed, a soft early systolic murmur is audible. This sound can become high-pitched, more intense, and holosystolic when the stenosis approaches 60%.  When the diameter reduces to 70%-80%, a bruit can is audible during systole and early diastole.  As the occlusion becomes very severe, blood flow turbulence becomes insufficient to cause vibratory sounds, and a bruit may disappear.[1]

Histopathology

A bruit from carotid artery stenosis is due to a carotid atherosclerotic plaque that can be both stable and unstable.  These plaques are similar to the other arterial plaques of the body.  The genesis of atherosclerosis begins with low-density lipoprotein (LDL) particles being trapped in the subintimal space by glycoproteins.  After the LDL particles become oxidized, a cascade of inflammatory response ensues, resulting in the formation of solid crystalline cholesterol that expands in volume, compromising the fibrous cap.  The fibrous cap maintains the integrity of the plaques and faces the vascular lumen.  Rupture of the fibrous cap leads to thrombosis, potential arterial lumen blockage, and distal embolization.  High-grade carotid stenosis is often found to have inflammatory cell infiltrates.  Additionally, intraplaque hemorrhage (IPH) has been found in symptomatic patients and has been shown to be predictive of future neurologic events and plaque rupture.  Several factors seem to influence plaque morphology.  Smoking may play a role in expediting atherogenesis. Men are also found to have high-risk plaque features compared to women.  Interestingly, age did now show a trend toward age-related plaque instability.[4]

History and Physical

Assessing patients for risks of cerebrovascular events start by taking a careful history and a focused physical exam. The optimum position for listening for a carotid bruit is with the patient either supine or sitting.  In the sitting position, optimal carotid palpation and auscultation are achievable when approaching the patient from behind.  With the patient’s chin pointing straight forward, the bell of the stethoscope is applied over the course of each carotid artery, sealing the overlying skin.  The patient is then instructed to inspire deeply and to hold the breath without bearing down for 15 to 30 seconds.  Auscultation continues during, and shortly after, the breath-holding.  Breath-holding not only eliminates other adventitious sounds, but it also accentuates a carotid bruit.[1] 

Evaluation

While a carotid bruit may alert clinicians to the presence of carotid artery disease, it is not sensitive and specific enough to diagnose carotid disease.[15]  On identification of a bruit, however, the next step is to determine whether the patient needs additional testing or referral; this usually depends upon the assessed vascular risk factors of the patient and/or the presence of signs and symptoms suggestive of any neuro-vascular disease.  Commonly, utilization of imaging studies such as carotid duplex ultrasound computed tomography angiography (CTA) and magnetic resonance angiography (MRA) of the neck help confirm the diagnosis and provide anatomical layout if a surgical invention is warranted.[16]  Collaboration with specialists like neurologists and cardiologists are also commonly employed.

Treatment / Management

Upon confirmation of carotid artery disease as the source of the carotid bruit, medical and surgical treatment should begin based on the severity of the stenosis, presence or absence of neurological symptoms, and the comorbidity of the patient.

Differential Diagnosis

  • Carotid stenosis
  • Carotid dissection
  • Cardiac valvular murmurs
  • Cervical venous hum
  • Cervical fibromuscular dysplasia
  • Extrinsic compression of the carotid artery
  • Intracranial arteriovenous malformations
  • Carotid artery vasculitis
  • High output clinical states like thyrotoxicosis
  • Carotid body tumors

Complications

The annual incidence of cerebrovascular accident in people with asymptomatic bruits is about 1 to 3 percent.[3]  Stroke is the second most common cause of mortality worldwide and the third leading cause of death in the United States.  Carotid artery disease contributes to 15 to 20% of all ischemic strokes.[4] 

Consultations

  • Neurology
  • Vascular surgery
  • Cardiology

Pearls and Other Issues

Asymptomatic carotid bruits are not infrequent, and their prevalence increases with age. This physical finding, however, has very low accuracy, and carotid bruit alone cannot be used to rule out or rule in carotid artery disease.[17]  However, if sensibly incorporated in the clinical assessment and risk stratification of the patient, it remains a viable tool in identifying patients at risk for a neuromuscular event.

Enhancing Healthcare Team Outcomes

Carotid bruits can be a significant clue to an underlying carotid artery disease.  Clear lines of communication between patient and the treatment team are important in expediting referrals and subsequent additional testing to exclude carotid artery disease and promptly institute measures to mitigate the chance of stroke.

While advanced imaging modalities such as carotid ultrasounds are more ubiquitous than ever, carotid auscultation as part of the physical examination is easy, cost-effective, and non-invasive.  These can be compelling reasons to continue including carotid auscultation as part of a routine physical examination especially in patients at risk for cerebrovascular disease.

Primary care providers should routinely evaluate at-risk patients fro carotid bruits. Physicians, nurse practitioners, and physician assistants evaluate for this finding. Nurses assist in patient education, facilitating evaluation, and provide feedback to the team. [Level 5]


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Carotid Bruit - Questions

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A 67-year-old is found to have an asymptomatic carotid bruit. Which of the following is the most appropriate next test?



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A patient has a carotid bruit. What symptom would indicate this is significant?



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During auscultation of the neck, bruit is heard. What does this signify?



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What is the most likely cause of a carotid bruit?



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Which of the following can be heard when there is turbulent blood flow in the carotid artery?



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While auscultating the carotid artery, a nurse hears a swooshing sound. What is true regarding this probable bruit? Select all that apply.



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Which of these conditions mimics carotid bruits from carotid artery disease?



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Which of these statements is true regarding carotid bruits?



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What is considered critical carotid artery stenosis?



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Which of these consultants is not typically involved in the evaluation of a patient found to have a carotid bruit from carotid artery disease?



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A 34-year-old female presents to the physician's office for evaluation of elevated blood pressure. The patient complained of a headache. She was found to have a carotid bruit on the right, but her examination otherwise was unremarkable. Her medical history included hypertension, and recently renal insufficiency. Her baseline creatinine was 1.1 mg/dL one month ago. Her family doctor added an angiotensin-converting enzyme (ACE) inhibitor two weeks ago to control her blood pressure further. She states that her blood pressure is usually around 160/80 mmHg. Also, she denies any prior surgeries, smoking, drinking, and use of drugs in the past as well. Her medications include a calcium channel blocker, an ACE inhibitor, and a beta blocker to control her blood pressure. Her vital signs include a blood pressure of 165/80 mm Hg, heart rate 80 bpm, respiratory rate 18/minute, temperature 98.9 F, and pulse oximetry of 99% on room air. The patient's laboratory data were unremarkable except for creatinine of 2.1 mg/dL. Her ECG was unremarkable. What is the most likely diagnosis?



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A 12-year-old male patient is being examined for a routine sports physical exam. His mom brought him in because a teammate collapsed recently during a game. The patient has no prior pertinent medical or surgical history and plays sports. The family history is unremarkable. During the exam, a continuous bruit was heard just above the internal jugular region. The bruit disappears with flexion of the head and with breath holding. The murmur intensifies during deep inspiration. The patient has normal vital signs and is otherwise without any complaints and is well appearing. What is the most likely etiology of the patient's findings?



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Carotid Bruit - References

References

Kurtz KJ, Bruits and Hums of the Head and Neck null. 1990     [PubMed]
Shorr RI,Johnson KC,Wan JY,Sutton-Tyrrell K,Pahor M,Bailey JE,Applegate WB, The prognostic significance of asymptomatic carotid bruits in the elderly. Journal of general internal medicine. 1998 Feb     [PubMed]
Louridas G,Junaid A, Management of carotid artery stenosis. Update for family physicians. Canadian family physician Medecin de famille canadien. 2005 Jul     [PubMed]
Mughal MM,Khan MK,DeMarco JK,Majid A,Shamoun F,Abela GS, Symptomatic and asymptomatic carotid artery plaque. Expert review of cardiovascular therapy. 2011 Oct     [PubMed]
Aronson L,Landefeld CS, Examining older people for carotid bruits: listen to your patient, not her neck. Journal of general internal medicine. 1998 Feb     [PubMed]
Grotta JC, Clinical practice. Carotid stenosis. The New England journal of medicine. 2013 Sep 19     [PubMed]
Aykan AÇ,Karadeniz A,Çavuşoğlu İG, Case Image: Bovine-type aortic arch and compression of the kissing carotid arteries by a retrosternal goiter: An uncommon cause of carotid bruit. Turk Kardiyoloji Dernegi arsivi : Turk Kardiyoloji Derneginin yayin organidir. 2018 Mar     [PubMed]
Anand J,Singh JP, Bilateral sporadic carotid body tumors-A rare case report. Radiology case reports. 2018 Oct     [PubMed]
Peric B,Marinsek ZP,Skrbinc B,Music M,Zagar I,Hocevar M, A patient with a painless neck tumour revealed as a carotid paraganglioma: a case report. World journal of surgical oncology. 2014 Aug 20     [PubMed]
Demiryoguran NS,Karcioglu O,Topacoglu H,Aksakalli S, Painless aortic dissection with bilateral carotid involvement presenting with vertigo as the chief complaint. Emergency medicine journal : EMJ. 2006 Feb     [PubMed]
Silver M, Takayasu's Arteritis - An Unusual Cause of Stroke in a Young Patient. The western journal of emergency medicine. 2012 Dec     [PubMed]
Plouin PF,Perdu J,La Batide-Alanore A,Boutouyrie P,Gimenez-Roqueplo AP,Jeunemaitre X, Fibromuscular dysplasia. Orphanet journal of rare diseases. 2007 Jun 7     [PubMed]
McColgan P,Bentley P,McCarron M,Sharma P, Evaluation of the clinical utility of a carotid bruit. QJM : monthly journal of the Association of Physicians. 2012 Dec     [PubMed]
Olin JW,Froehlich J,Gu X,Bacharach JM,Eagle K,Gray BH,Jaff MR,Kim ES,Mace P,Matsumoto AH,McBane RD,Kline-Rogers E,White CJ,Gornik HL, The United States Registry for Fibromuscular Dysplasia: results in the first 447 patients. Circulation. 2012 Jun 26     [PubMed]
van der Worp HB,van Gijn J, Clinical practice. Acute ischemic stroke. The New England journal of medicine. 2007 Aug 9     [PubMed]
Qaja E,Theetha Kariyanna P, Carotid Artery Stenosis null. 2018 Jan     [PubMed]
Sauvé JS,Laupacis A,Ostbye T,Feagan B,Sackett DL, The rational clinical examination. Does this patient have a clinically important carotid bruit? JAMA. 1993 Dec 15     [PubMed]

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