Tag: subclavian steal syndrome

Subclavian Steal Syndrome

Case Report and Discussion

Hema Manvi Koneru, MBBS
Rajiv Gandhi Institute of Medical Sciences, Telangana, India.

Amanpreet Kaur, MBBS
Government Medical College Patiala, India.

Divyasri Koneru, MBBS
Dr.Pinnamaneni Siddhartha Institute of Medical Sciences and Research Foundation, India

Amin H. Karim MD FACC,
Clinical assistant professor, Baylor College of Medicine, Houston, Texas.

A 74-year-old male presented with complaints of dizziness. His medical history includes hypertension, diabetes mellitus, mitral regurgitation, tricuspid regurgitation, and a transient ischemic attack five months prior. Additionally, he reported two episodes of memory lapses within the past year.

The patient denied experiencing orthopnea, paroxysmal nocturnal dyspnea, chest pain, smoking, shortness of breath, leg swelling, speech disturbances, disequilibrium, blurry vision, syncope, tinnitus, hearing loss, ataxia, numbness, tingling, pins, and needles in the arms or legs.

MEDICATIONS

Aspirin 81mg sustained-release oral tablet, once daily; atorvastatin calcium 80mg tablet, taken orally once daily; clopidogrel 75mg tablet, taken orally daily; dulaglutide 0.75mg/0.5ml subcutaneous pen injector, administered subcutaneously once weekly; gabapentin 300mg oral capsule, taken once daily; losartan 25mg tablet, taken orally once daily; metformin hydrochloride 750mg extended-release tablet, taken twice daily with meals; nitroglycerin 0.4 mg sublingual tablet, to be used when chest pain persists; and thiamine 100 mg oral tablet, taken once daily. These medications have been prescribed to effectively manage the patient’s medical conditions and symptoms.

The patient had a history of allergy to the contrast medium used for the radiological examination.

LAB WORKUP

  • HBA1C-6.6gm/dl
  • The rest of the blood reports- are within in normal range.

ELECTROCARDIOGRAM

  • Sinus tachycardia with nonspecific ST-abnormality

CTA CORONARY ARTERIES

  • There is severe coronary calcification. The observed calcium score is 780, which is at the 75th percentile for subjects of the same age, gender, race/ethnicity who are free of clinical cardiovascular disease and treated diabetes.
  • Moderate to severe, predominantly calcified. Coronary artery disease involving proximal and LAD with moderate luminal stenosis. FFR-CT was performed on the LAD which showed significant flow limitation of the mid-LAD (left anterior descending artery).

CTA OF BRAIN AND NECK

  • Brain–moderate chronic microvascular ischemia, suprasellar 8 x 7 mm partially calcified lipoma or dermoid cyst.
  • Neck-Complete occlusion of the left vertebral artery V1 and V2 segments. Atherosclerosis of bilateral extracranial carotid arteries without significant stenosis.
  • The head shows no significant stenosis or occlusion.

MRI BRAIN

  • No acute ischemia.
  • Hypothalamus showing non-enhancing mass suggestive of Lipoma/Dermoid cyst.
  • Moderate chronic microvascular ischemia.

ECHOCARDIOGRAM

  • Mild left ventricular hypertrophy.
  • Trace tricuspid regurgitation.
  • Mitral regurgitation.
  • Left ventricular dysfunction.

NUCLEAR STRESS TEST

  • A small area of perfusion defect in the inferior wall which fills with reperfusion

CAROTID ULTRASOUND

No occlusive disease.

Following a thorough workup and assessment of the patient’s clinical presentation, imaging studies, and diagnostic tests, a final diagnosis of subclavian steal syndrome was made. This condition is attributed to the underlying pathology of atherosclerosis which mainly affects the subclavian artery.

DEFINITION

It is characterized by the retrograde flow of blood in the vertebral artery, primarily resulting from significant stenosis or occlusion in the pre-vertebral subclavian artery resulting in cerebrovascular symptoms on the ipsilateral side of the occlusion.

§ During exertion, the subclavian artery steals blood from the vertebrobasilar artery circulation to supply the arm, which leads to vertebrobasilar insufficiency.

SUBCLAVIAN STEAL PHYSIOLOGY

EPIDEMIOLOGY

The prevalence of subclavian steal syndrome has not been well defined, although subclavian steal physiology has been reported in 1.3 to 2.6% of the general population of patients with extracranial atherosclerosis (1,2) as well as within subsets of those presenting with acute ischemic stroke (3)

ETIOLOGY

  • The most common cause is atherosclerosis.
  • Other vascular causes- Takayasu arteritis, giant cell arteritis
  • Arterial thoracic outlet syndrome
  • Congenital anomalies- anomalies of the aortic arch, anomalies of the brachiocephalic trunk
  • A consequence of corrective surgery- surgical repair of the Tetralogy of Fallot with a Blalock-Taussig anastomosis, surgical management of the coarctation of the aorta.
  • Hemodialysis vascular access associated (AV fistula).

Subclavian stenosis more commonly occurs on the left side (>75 percent), possibly due to more acute origin on the left subclavian artery resulting in accelerated atherosclerosis from increased turbulence. (4,5,6)

CLINICAL FEATURES

Neurovascular symptoms can be caused by vertebrobasilar ischemia of the brainstem or cerebellum

  • Symptoms include dizziness, vertigo, binocular double vision, dysarthria, syncope, and drop attacks (sudden falls without loss of consciousness) (7)
  • Episodes can be precipitated by exercise of the ischemic arm and precipitated by certain head movements.

Atypical neurological presentations- there is also increasing recognition that patients with vertebrobasilar insufficiency can present with other types of symptoms not directly attributable to brainstem or cerebellar ischemia.

  • Subarachnoid hemorrhage (8)
  • Cognitive and mood abnormalities

EVALUATION

Although neurovascular symptoms associated with subclavian steal physiology occur in only a minority of patients, symptoms of vertebrobasilar ischemia demand critical evaluation (10,11)

When to suspect subclavian steal syndrome

  • Diagnosis should be considered in patients with a measurable upper extremity blood pressure differential who develop episodic neurological symptoms attributable to the brainstem or cerebellar ischemia.
  • Suspicion is increased if the episodes are provoked by arm exercise, especially if accompanied by ischemic arm symptoms (7)

PHYSICAL EXAMINATION

  • All major pulses should be palpated, and blood pressure should be checked in both arms.
  • It is important to examine the subclavian arteries in the supraclavicular fossa using palpation and auscultation for paraventricular bruits, also vertebral and carotid arteries for the evidence of any occlusive arterial disease.
  • On examination, there may be a significant decrease in the blood pressure on the affected side with a pulse delay appreciated when palpating the radial arteries simultaneously known as RADIO-RADIAL DELAY.
  • Check for any evidence of thromboembolism in the skin of the hands and nailbeds of the affected extremities.
  • Ischemia affecting the temporo-occipital areas of the cerebral hemispheres or segments of the brainstem and cerebellum characteristically produces bilateral symptoms.

RADIOLOGICAL EXAMINATION

Initial vascular imaging

1. Duplex ultrasound

  • A subclavian artery peak systolic velocity >240cm/sec is predictive of a significant (>70 percent) subclavian artery stenosis (9)
  • When severe stenosis (>80 percent narrowing) of the proximal subclavian artery is present, 65 percent of pa>ents have permanent flow reversal in the ipsilateral vertebral artery, and 30 percent have intermittent flow reversal (10,11)

2. Transcranial doppler ultrasound

Confirmatory vascular imaging

  1. Computed tomographic angiography (CTA)-provides precise measurement of the severity of the stenosis. main drawback is the absence of dynamic flow information.
  1. Magnetic resonance angiography (MRA)- sensitive than CTA. Does not depict images of arterial anatomy but rather the behavior and speed of the flowing protons in the vessel. Also provides information on the intracranial cerebrovascular circulation.
  1. Catheter-based digital subtraction angiography (DSA)

DIAGNOSIS

DIAGNOSTIC CRITERIA– the presence of subclavian steal physiology with demonstration of a subclavian artery stenosis/ occlusion proximal to the origin of the vertebral artery causing

  • Marked reduction in the ipsilateral brachial artery blood pressure.
  • Reversal of the direction of blood flow in the ipsilateral vertebral artery
  • Neurological symptoms referrable to the vertebrobasilar circulation (cerebellum, brainstem, thalamus, occipital regions)

The likelihood that the presence of subclavian steal physiology will lead to the subclavian steal syndrome increases as the brachial pressure differential between the two limbs becomes more pronounced, particularly >40mmhg (5)

DIFFERENTIAL DIAGNOSIS

These include all the potential causes of vertebrobasilar embolism due to atherosclerosis, hypertension, hypercoagulable states, tumors, tobacco smoking, trauma, and others

MANAGEMENT

Management of patients with subclavian steal syndrome is individualized depending on the etiology, type, and severity of symptoms and their impact on quality of life

ATHEROSCLEROTIC SUBCLAVIAN STEAL SYNDROMEAPPROACH

For most patients with atherosclerosis as the etiology for subclavian steal syndrome, conservative management is the preferred initial therapy.

Initial medical management

  • Start with the low-dose aspirin.
  • However, the addition of other anti-platelet drugs does not seem justified since this condition is hemodynamic derangement. once a decision is made for surgical management, additional anti-thrombotic agents are required.
  • Optimal blood pressure management is required within the ipsilateral side brachial artery.

Surgical management

  • Proximal subclavian endarterectomy, which is a trans-thoracic approach used for revascularizing the subclavian artery.
  • Re-vascularization surgery via endovascular techniques (carotid-subclavian bypass or subclavian-carotid transposition).
  • Carotid intervention in patients with severe concomitant carotid artery disease helps to improve cerebral perfusion.

NON-ATHEROSCLEROTIC SUBCLAVIAN STEAL SYNDROME

  • For non-atherosclerotic subclavian syndrome etiologies, the primary cause needs to be addressed.
  • Example- Takayasu arteritis is by systemic glucocorticoids or steroid-sparing agents like biological DMARD (Disease Modifying Anti-Rheumatoid Drugs) or non-biological DMARD

CONCLUSION

This case highlights the importance of a detailed evaluation of subclavian steal syndrome can be due to atherosclerosis or non-atherosclerotic causes like Takayasu arteritis, giant cell arteritis, arterial thoracic outlet syndrome, and other causes. In our case, it might be a subclavian steal syndrome secondary to atherosclerosis.

REFERENCES

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