As imaging techniques tend to improve day by day, we are on the edge of forgetting the importance of a good old physical examination. With InSimu, our primary goal is to teach medical students the basics of medicine. You don’t have to perform a full-body CT, just to diagnose PTX, BPPV, or today’s main focus, carotid artery disease. Auscultation is a simple, safe and inexpensive diagnostic tool and it is especially crucial in diagnosing vascular problems. So, here you have a detailed guide about carotid (and other) bruits and what you should know about them.
What is a bruit?
A bruit is an audible vascular murmur. Normal blood flow is laminar, but when it becomes turbulent (non-laminar), bruits can occur. Sometimes, it is not only possible to listen to the bruits with your stethoscope, but you can also feel the turbulent flow with your fingers as a thrill. These bruits may be innocent and harmless, but may point to an underlying disease that needs our attention.
A bruit sound can be localised anywhere on the body, above different kind of vessels. Let’s just mention the important types of bruits by location:
- Head & neck
- cranial and orbital (coming from intra-, or extracranial vessels, it’s indicated to look for them when craniocervical symptoms - such as seizures or headaches - are present)
- cervical (can be arterial, coming from the carotid arteries, or venal. To differentiate them, it’s crucial to know that the venal bruits are usually higher pitched than the carotid bruits)
- supraclavicular (can be a sign of arm claudication or subclavian steal syndrome)
- renal artery (stenosis; causing renovascular hypertension)
- aorta (aneurysm)
- different tumors (they tend to compress vessels externally, causing turbulent flow)
- Limbs (most commonly on the lower limbs)
- iliac artery
- femoral artery
- popliteal artery
How do you listen to bruits?
First of all, get your patient into a quiet exam room, in a relaxed and comfortable position - as you would do when performing a routine physical examination. Well, actually listening to the carotids should be the part of a standard check-up. It is recommended to use the diaphragm of your stethoscope when looking for bruits as it’s more suitable for detecting the higher frequency sounds of arterial bruits.
This applies to all different blood vessels, but today we are focusing on the neck, more specifically on the carotids. So the next thing you’ll do is to ask the patient to breathe in and hold their breath. Listen over the line of the common carotid artery leading up to the bifurcation into the internal and external carotid arteries. Don’t press too hard to avoid compressing the underlying artery (this way you can cause a bruit sound even in a healthy artery!), but make sure that the stethoscope rests squarely on the skin.
Do you want to know how a carotid bruit sounds? Click here to listen!
What does a bruit indicate?
Bruits most commonly indicate a stenotic lesion, which causes arterial wall vibrations distal to the blockage. These vibrations are transmitted to the body surface, where they can be detected with a stethoscope or - as mentioned above - your finger. A carotid bruit may develop when the arterial lumen is 50% smaller than its original cross-sectional diameter. Stenosis is mainly caused by atherosclerosis - so it is important to mention that carotid bruits are great indicators of generalized atherosclerosis therefore of ischaemic heart disease.
However, a bruit sound heard on the neck area can indicate a LOT more:
- A supraclavicular arterial bruit can even be normal in young adults (although it can mean severe stenosis of subclavian or vertebral artery).
- Diffuse neck bruit may be a sign of thyrotoxicosis or other causes of a hyperdynamic circulation (for example, anaemia, pregnancy, or fever).
- Another possible reason could be that the murmur is originated from the heart itself and transmitted to the neck. Aortic valve stenosis, mitral valve regurgitation should be ruled out with an echocardiogram.
- Transmission from the great vessels can also be the pathology behind a bruit (like a patent ductus arteriosus, or coarctation of the aorta).
How do you assess the carotid for bruits?
As we mentioned before, it is recommended to look for bruits, especially in the cervical area because positive findings can indicate further investigation. Carotid arteries are two large blood vessels on the neck, carrying oxygenated blood to the frontal part of the brain. If the blood supply is compromised, it can severely affect personality, thinking, speech, sensory and motor function. In InSimu Patient, we’re encouraging you to always look at the whole picture, not just one pathological finding or symptom but the patient itself.
So what should you do after realising that you hear a bruit over the carotid?
- So, if the patient has no symptoms at all and you noticed this carotid bruit without expecting it, you don’t need to panic right away. The brain has significant collateral circulation, so if only one carotid is narrowed, it can be compensated quite well. However, a carotid duplex screening where you can actually visualise this turbulent blood flow is recommended, if multiple risk factors are present. These risk factors are the following: age, smoking, hypertension, high cholesterol, diabetes, obesity, sedentary lifestyle, etc.
- If the patient is symptomatic (see next question for details), and you’re actually looking for bruits, besides the ultrasound, you have other options you should consider. The gold standard for diagnosing carotid artery stenosis is cerebral angiography, but CTA (Computed Tomography Angiography) and MRA (Magnetic Resonance Angiography) are also available methods. All of these methods have their pros and cons, you should select the best one, individualised to each patient.
What are the symptoms of carotid artery blockage?
As we discussed before, the most common reason behind a carotid bruit is atherosclerosis. We already mentioned the risk factors (which will be later important in therapy), now let’s focus on the symptoms. First of all, it’s important to know that carotid artery blockage can be asymptomatic for quite a long time.
Acute, severe symptoms are basically the signs of TIA (Transient Ischaemic Attack) or stroke:
- Sudden loss of vision, blurred vision (amaurosis)
- Weakness or numbness on one side of the body
- Sudden difficulty in walking, loss of balance, lack of coordination (vestibular symptoms)
- Sudden dizziness
- Sudden severe headache
- Problems with memory
- Problems with swallowing (dysphagia)
However, it’s important to mention that carotid artery blockage can be the reason behind dementia (it is called the vascular type dementia).
How to treat carotid artery blockage?
It depends on quite a few things (like the presence of symptoms, and their severity or the size of blockage). In earlier stages, lifestyle changes can successfully prevent further development of the disease. Drug therapy focuses on decreasing the effects of risk factors (like statins for high cholesterol levels) and anticoagulation to avoid thrombosis on the surface of the plaque. Intervention treatments are advisable in later stages: two options are available today - CEA (carotid endarterectomy) or CAS (carotid angioplasty and stenting).
Degree of carotid stenosis
| || || |
| || || |
This table is from Ferri’s Clinical Advisor (2018)