Exam 3 - Normal Carotid Anatomy & Waveforms

Transducer used for carotid exams

Linear - low/medium frequency

Small footprints - when catheters present

CCA

Left - from AO arch

Right - from brachiocephalic A.

Bifurcates into ICA & ECA

ICA

Scan more lateral

3 segments - cervical, petrous, intracranial

Ophthalmic A is first branch

Cervical branch of ICA

Lies lateral and posterior

No extracranial branches

Petrous branch of ICA

Lies vertical and horizontally

Through temporal bone

Intracranial branch of ICA

Divides into cavernous and supraclinoid segments

Ophthalmic Branches of Periorbital Circulation

Supraorbital A

Frontal A

ECA

Scan more medial

8 branches to head/face/neck

Superficial thyroid A. is first branch

ECA Branches of Periorbital Circulation

Facial A

Nasal A

Indications of Collateral Flow

Internalization of ECA

Reversal of flow in Ophthalmic A

Veterbral A

Find CCA, angle posteriorly

Originates from posterior portion of subclavian A

Courses beside ICA

Left is larger/prominent

Enters transverse processes of spine at C6

Enters cranium via foramen magnum

Jugular Veins

Main source of head/neck drainage

Internal Jugular V

Flows into brachiocephalic V

External Jugular V

Flows into subclavian V

Carotid Protocol

Prox CCA - close to AO arch

Mid CCA

Distal CCA - just before bulb

Prox ICA - just after bulb

Mid ICA

Distal ICA

Prox ECA - showing first branch if possible

Spectral Doppler with PSV at each point

Doppler Characteristics of Carotid A

Low resistant - except prox. CCA & ECA

High off baseline

Spectral window

Continuous forward flow

Normal Prox CCA Waveform

Normal CCA Waveform

Normal ICA Waveform

Lowest resistance

Carotid Bulb

Normal to have turbulent flow at separation/divider

Normal ECA Waveform (with temporal tap)

High resistant

Normal Vertebral A Waveform