Diagnostic Medical Sonography Program - PowerPoint Presentation

Slide1

Diagnostic Medical Sonography Program

Lecture 21: Miscellaneous Conditions, Diagnostic Tests, and Treatment

Holdorf

Arterial Miscellaneous Conditions, Diagnostic Tests, and Treatments

Condition: Subclavian Steal

Subclavian occlusion results in retrograde flow in ipsilateral vertebral artery.

Alternating flow usually correlated with angiographic evidence of high-grade subclavian stenosis

Patients with subclavian occlusion are usually asymptomatic: are claudication is rare

May have blood pressure difference of > 15-20 mmHg; may have decreased pulses in affected arm.

Ipsilateral vertebral artery feeding high-resistance vascular bed

Surgical treatment may include a bypass graft or endarterectomy

Subclavian Steal

Condition:

Temporal arteritis

Inflammation of the arterial wall of the superficial temporal artery or its front and or parietal branches

Inflamed arterial segments often larger in diameter with homogeneous thickening evident on B-mode

An anechoic HALO from edema of the intima may be seen

Intimal thickening may result in significant stenosis where PSVs are doubled

Superficial Temporal ArteryTerminal branch of the ECAAscends in front of ear – where it is palpable

Temporal arteritis

Miscellaneous Diagnostic Tests

Arteriography:

Interpretation

Normal anatomy should be visualized

Abnormalities include:

Filling defect

Absent vessel

Aberrant anatomy

Percent stenosis calculated

Normal Anatomy

Filling Defect

Example for calculating Diameter ReductionDiameter reduction: D = 8mm, d = 2mm1 – (d/D) x 100 =1 – (2/8) x 100 =1 – (.25) x 100 = .75 x 100 = 75%

Calculated % stenosis based on NASCET study:North American Symptomatic Carotid Endarterectomy Trial

What is an Endarterectomy?

Surgical removal of part of the inner lining of an artery, together with any obstructive deposits, most often carried out on the carotid artery or on vessels supplying the legs.

The North American Symptomatic Carotid Endarterectomy Trial (NASCET) demonstrated a conclusive benefit for carotid endarterectomy in patients with symptomatic 70-99% ICA stenosis.

MR Angiography

Extremely sensitive to the presence of stenosis, but tends to overestimate the disease process

May be used when a carotid duplex study is equivocal or technically limited

CT

Most frequent application in cerebrovascular disease: evaluate the nature of cerebral infarctions, intracranial aneurysms, hemorrhage and AVMs

Treatments

Medical

Lifestyle modifications

Stop smoking

Weight control and low cholesterol diet

Pharmacological

Aspirin: an anti-platelet drug that decreases platelet aggregation resulting in decreased thrombotic activity

Treatments

Surgical

Stenosis: Endarterectomy: Surgical removal of atherosclerotic material

Occlusion: Usually receives no surgical intervention

Treatments

Endovascular (Stent)

Designed to maintain the intraluminal structure and patency of the artery; acts as a type of “scaffold”

Increasing use of stents in carotid artery stenosis: may expect some flow acceleration post-stenting

Additional Notes

Miscellaneous- conditions, diagnostic tests, and treatment

Subclavian steal

In the vertebral artery, demonstrates alternating “Too-Fro” flow velocities (high systolic component – positive- component, and a very low – below the baseline, diastolic component.

Normally, the vertebral artery demonstrates low resistance flow velocity.

Proximal occlusion: proximal to the ipsilateral vertebral artery. Blood is not getting to the distal arm, so the vertebral artery “saves the day” by supplying the blood, hence reversal of blood flow.

Temporal arteritis

Will see an inflammation HALO

No Biopsy for this.

NASCET study – North American Symptomatic Carotid Endarterectomy trial

Treatment of choice for significant Carotid stenosis or occlusion is the Endarterectomy, which completely removes the plaque.

Take the distal CCA diameter that is free of stenosis example 5cm

Take the diameter that is open between the stenosis example 2cm

Divide the smaller number by the bigger number

1 – (2/5) x 100 = 40 – 100 60 x 100 = 60% diameter reduction.

Treatment-

Endovascular stent

Expect FAST FLOW through the stent.

If getting 125 cm/sec, then this is abnormal.

Expect very high numbers: example: 400 cm/sec.

Homework

Textbook:

Chapter 22: Atypical Vascular Disorders

Chapter 23: Alternative Diagnostic Tests and Therapeutic Interventions

Pages: 249 – 262

SDMS Assignments