23  Rapid Review

Authors: Matthew Chia and Maggie Reilly

In this chapter we discuss a number of disparate topics that are often seen on the VSITE examination in the US, and often just require rote memorization. We have included links to the relevant chapters for you to see the information in more context if needed. This chapter is not meant as a stand a lone review.

23.1 Venous Disease

Memorization CEAP classification:

  • C0: no visible or palpable signs of venous disease.

  • C1: telangiectasias or reticular veins.

  • C2: varicose veins.

  • C3: edema.

  • C4a: pigmentation and eczema.

  • C4b: lipodermatosclerosis and atrophie blanche.

  • C5: healed venous ulcer.

  • C6: active venous ulcer.

EHIT (DVT after EVLA), endothermal heat-induced thrombosis

  1. Thrombus without propagation into the deep vein: no treatment

    a. Peripheral to superficial epigastric vein

    b. Central to superficial epigastric vein, up to and including the deep vein junction: can consider antiplatelets

  2. Thrombus propagation into the adjacent deep vein but comprising <50% of the deep vein lumen: weekly surveillance

  3. Thrombus propagation into the adjacent deep vein but comprising >50% of the deep vein lumen: therapeutic anticoagation until resolution to the SFJ

  4. 4. Occlusive deep vein thrombus contiguous with the treated superficial vein: treat like DVT

Reasons to treat superficial venous thrombosis (fondaparaneux x 45 days)

  • Within 3-5 cm of deep system (e.g., SFJ)

  • > 5cm long

  • Propagates with conservative management

For more see Chapter 18

23.2 Vascular Lab

23.2.1 TCD

TCD temporal window:

  • Toward probe is up on waveform (MCA, ICA)

  • Away from probe is down on waveform (ACA)

  • PCA is bidirectional (P1 before PCommA is up, P2 after PCommA is down)

TCD orbital window:

  • Ophthalmic is toward probe

  • ICA in siphon is bidirectional

TCD occipital window:

  • vertebral and basilar away from probe (think direction on carotid duplex)

Consider shunt during CEA if MCA velocity drops by 50% or more A doubling of MCA mean velocity suggests cerebral hyperperfusion syndrome

Lindegaard ratio 3-6 indicates spasm, > 6 indicates severe spasm. PSV in MCA relative to extracranial ICA.

For more see Section 20.3

23.2.2 Basics

Power doppler is like amplitude, good for low flow evaluation but you lose directionality (think absolute values). Good for detecting string sign, low flow in renal parenchyma, or torsion. Not useful for directionality of flow (e.g., TCD or vertebral direction), and will not alias.

Depth resolution (synonymous with axial, longitudinal range) in PW mode is limited by half the spatial pulse length (SPL). As long as the resolution between objects is less than half the SPL, objects can be discriminated (because the total distance doubles going round). Shorter SPL means you can distinguish smaller things, which means better (smaller) resolution. Shorter SPL theoretically is achieved by shorter wavelength/higher frequency, more damping, shorter pulse duration. It is not technically affected by PRF/PRP.

PRP = time between pulses = imaging depth (ID) * 13 microseconds/cm note that PRF = 1/PRP, and that PRFs are generally 5-40 kHz

Maximum Doppler shift detectable = Nyquist limit = PRF/2. Remember this only applies to PW Doppler. CW Doppler has no practical limit beyond which aliasing occurs. Use caution between depth resolution (2x SPL) and Nyquist limit (1/2 PRF)

For more, see Section 20.1

23.2.3 Sizes and Velocities

Intracranial aneurysm and carotid stenosis: no need to treat if < 10mm

(Chaer et al. 2020)

AAA screening

  • In any pt with suspected or confirmed AAA, physical exam of femoral + popliteal pulses

  • Any pt with femoral or popliteal aneurysm should undergo AAA screening

  • Men or women 65-75 years w/ h/o tobacco use (SVS recommendation)

AAA surveillance

  • 2.5-3cm: 10 years

  • 3-3.9cm: 3 years

  • 4-4.9cm: 1 year

  • 5-5.4cm: 6 months

Carotid velocities

  • > 70%

    • PSV > 230

    • EDV > 100

    • ICA/CCA > 4.0

  • > 50%

    • PSV > 125

    • EDV > 40

    • ICA /CCA > 2.0

CMI velocities

  • CA PSV > 200

  • SMA PSV > 275

Renal stenosis criteria

  • PSV > 200 (some advocate for PSV > 285)

  • RAR > 3.5, but aortic velocity should be 40-100 cm/s

  • Parenchymal disease is RI > 0.7

    • (PSV-EDV)/PSV

23.3 Zebras

Indications for surgical management of vertebral disease

  • At least 60% stenosis

    • In both arteries if patent

    • In one artery if contra is hypoplastic, occluded, or terminates in PICA

  • If low flow: other etiologies have been ruled out (arrhythmia, emboli, inner ear dysfunction, electrolyte imbalance, intracranial tumor, hypotension)

  • Posterior embolism should be considered for treatment

  • Location

    • V1 can be treated by transposition onto CCA or vein bypass

      • Proximal vertebral artery reconstruction is associate with Horner’s syndrome

    • V2 not usually accessible, if uncontrolled traumatic hemorrhage, ligate at V1+V3

    • V3 disease described treatments include by bypass, transposition of ECA or occipital artery, or transposition onto ICA

For more, see Section 1.5.2

Surgical exposure of supra-aortic vessels

  • Median sternotomy for: innominate, proximal R SCA, R CCA, and L CCA

  • L trapdoor (L anterolateral thoracotomy and supraclavicular incision) for proximal L SCA

    • Watch for L vagus n. and thoracic duct in chest, and watch for phrenic n. on anterior scalene

MALS: compression with EXPiration, normalization with INSPiration

Electrolyte abnormality with re-feeding

  • Phos down (ATP)

  • K, Mg down (taken intracellular for anabolism)

    • Mg down can lead to Ca down

  • Torsades can be caused by low K, Mg, or Ca > treat with Mg

Popliteal artery disease

  • Baker’s cyst vs cystic adventitial disease (knee flexion)

    • Baker’s cyst is contiguous with joint space

    • Cystic adventitial disease is within the arterial wall

  • Popliteal entrapment (passive dorsiflexion or active plantar flexion)

  • Popliteal artery aneurysms

    • If patients present with PAA, need screening for AAA

    • Above 2 cm should undergo repair, unless high clinical risk may wait until 3 cm

    • Can also consider repair at smaller sizes if high embolic risk

    • If life expectancy > 5 years, should undergo open repair

    • If acutely thrombosed

      • I + IIa should undergo lysis if tibial outflow bad

      • IIb should undergo thrombectomy of some fashion

      • III undergo primary amputation

For more, see Section 17.4

HITT

  • 4 Ts

    • Thrombocytopenia - Platelets fall > 50% and are less than 20k

    • Timing - Clear onset between 5-10 days or > 1 day w/ previous heparin exposure

    • New Thrombosis

    • No other cause for Thrombocytopenia

  • Bivalirudin if hepatic failure

  • Argatroban for renal failure (OK for hepatic fail, but needs titration)

Obturator foramen

  • Valentine/Wind

    • Nerve and vessels traverse the foramen superolateral corner

    • Tunnel should be created “centrally” by incising the medial portion of fascia

  • Chaikof/Cambria

    • Nerve and vessels traverse posterolaterally

    • Tunnel should be created anteromedially

  • Rutherford

    • Nerve and vessels are posterolateral

    • Tunnel should be created anteromedially