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Diagnostic ultrasound ( PDFDrive )

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CHAPTER 26 The Extracranial Cerebral Vessels 953

A

B

FIG. 26.51 Reversal of Vertebral Artery Flow in Subclavian Steal. Subclavian steal causes reversed low in vertebral artery. Spectral Doppler

(A) demonstrates complete vertebral artery low reversal due to right subclavian artery occlusion. Color-low Doppler (B) demonstrates low toward

the transducer.

Abnormal Vertebral Artery Waveforms

COMPLETE SUBCLAVIAN STEAL

Reversal of low within vertebral artery ipsilateral to

stenotic or occluded subclavian or innominate artery

INCOMPLETE OR PARTIAL SUBCLAVIAN STEAL

Transient reversal of vertebral artery low during systole

May be converted into a complete steal using provocative

maneuvers

Suggests stenotic, not occlusive, lesion

PRESTEAL PHENOMENON

“Bunny” waveform: systolic deceleration less than

diastolic low

May be converted into partial steal by provocative

maneuvers

Seen with proximal subclavian stenosis

FIG. 26.52 Incomplete Subclavian Steal. Flow in early systole is

antegrade, low in peak systole is retrograde, and low in late systole

and diastole (arrow) is again antegrade.

TARDUS-PARVUS (DAMPENED) WAVEFORM

Seen with vertebral artery stenosis

artery pathology on angiography. hese include the complete

subclavian steal, partial or incomplete steal, presteal phenomenon,

and tardus-parvus vertebral artery waveforms. 239,244 In a complete

subclavian steal, low within the vertebral artery is completely

reversed (Fig. 26.51). Incomplete steal or partial steal demonstrate

transient reversal of vertebral low during systole 239,245

(Fig. 26.52). Incomplete steal suggests high-grade stenosis of the

subclavian or innominate artery rather than occlusion. Provocative

maneuvers, such as exercising the arm for 5 minutes or 5-minute

inlation of a sphygmomanometer on the arm to induce rebound

hyperemia on the side of the subclavian or innominate lesion,

can enhance the sonographic indings and convert an incomplete

steal to a complete steal. 155,185

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