Pulsed Doppler assessment of innominate artery obstructive diseases.

In 14 patients with severe stenosis or occlusion of the innominate artery a new high-energy, low-frequency (2 MHz) pulsed Doppler ultrasound method was used to investigate blood flow velocity patterns of both intrathoracic and intracranial cerebral arteries. Direct acquisition and evaluation of the innominate artery at its origin near the aortic arch enabled separation of it from adjacent arteries and reliable differentiation of stenosis from occlusion. Transcranial recordings from the basal cerebral arteries showed abnormal Doppler signals in 12 patients (86%). Among these abnormalities, observation of a latent steal phenomenon was closely related to the prevalence of cerebrovascular events. This latent steal phenomenon was characterized by a transient reduction of orthograde blood flow in the ipsilateral anterior, middle, and posterior cerebral arteries or in the basilar artery during postischemic hyperemia of the upper extremities. The predictive value of the latent steal phenomenon for the management and follow-up of asymptomatic patients with severe innominate artery obstructions is discussed.