Chapter 23 - Vascular lab - venous duplex

Question 1

Venous duplex transducer frequency

Answer 1

5-10 MHz 3-5 MHz for deeply located vessels IVC and iliac vein or obesity

Question 2

Normal venous flow with respiration

Answer 2

Phasic flow inspiration = diaphragm moves down, intraabdominal pressure increased, intrathoracic pressure decreased - decrease venous return from LE - increase venous return from UE expiration - increase venous return from LE - decrease venous return from UE

Question 3

Augmentation maneuvers on venous duplex

Answer 3

1) calf pump 2) manual distal compression

Question 4

Rate of progression or recurrent thrombosis in patients with symptomatic calf-vein DVT

Answer 4

15-20% in 3 months

Question 5

Timing of follow-up duplex in patients not on anticoagulation with isolated calf vein thrombi

Answer 5

2 weeks

Question 6

Sen and spe for duplex on UE DVT

Answer 6

sensitivity 84-97% spe 93-96%

Question 7

Ultrasound features to determine venous thrombus age

Answer 7

TABLE 23.3

Question 8

Terminology to describe chronicity of venous thrombosis

Answer 8

Acute DVT Venous thrombosis indeterminate age chronic postthrombotic change

Question 9

Ultrasonic elastography describe

Answer 9

Use ultrasound imaging to measure soft tissue strain to objectively assess mechanical properties of tissue (hardness/stiffness)

Question 10

Define elasticity

Answer 10

tendency of material to resume original size and shape after deformation

Question 11

Define strain

Answer 11

Changes in size or shape

Question 12

Define stress

Answer 12

force acting on an area

Question 13

Three moduli that describe elasticity

Answer 13

1) Young modulus - longitudinal elasticity = ratio of stress to strain 2) shear or torsion modulus = rigidity 3) bulk or volume modulus = volume elasticity

Question 14

Define acoustic radiation force impulse imaging and how it works

Answer 14

ARFI uses energy of insonated US to move tissue at microscopic level - focused US beam pass through soft tissue - mainly attenuated through absorption - some create tissue movement causing deformational stress - greater effect on softer tissues

Question 15

Two types of elastography to assess thrombus elasticity

Answer 15

Shear wave elasticity imaging (SWEI) Shear wave induced resonance elastography (SWIRE)

Question 16

Finding of the DACUS study on recurrent DVT

Answer 16

Duration of anticoagulation based on compression ultrasonography residual thrombus in proximal veins were associated with increased risk of recurrent thrombus after DVT

Question 17

Risk of recurrent thrombosis in cancer patients with DVT after 6 months of anticoagulation

Answer 17

15% in 1 year

Question 18

PROLONG study on recurrent DVT

Answer 18

Elevated D-dimer at 1 month after anticoagulation withdrawal associated with recurrence residual venous obstruction not associated

Question 19

Rate of vein postthrombotic abnormalities after DVT at 3 months and 1 year

Answer 19

80% 3 months 50% 1 year

Question 20

Define suppurative thrombophlebitis

Answer 20

Bacterial infection of thrombosed vein

Question 21

Trousseau sign of malignancy

Answer 21

Recurrent, migratory thrombosis in superficial veins including uncommon sites (torso, UE) Associated with adenocarcinoma especially pancreas or lung

Question 22

Ultrasound exam pre-op on AVF maturity and usability

Answer 22

Assisted primary patency 1 year 80 vs 65%

Question 23

Characteristics considered suitable for use as bypass conduit in vein

Answer 23

1) compressible at all level 2) no intraluminal echoes 3) no thickened walls 4) > 0.25 cm 5) uniform caliber without tortuosity 6) no varicose segments or multiple branches 7) not superficial to fascia

Question 24

Three levels on the diagnostic assessment for chronic venous disorder

Answer 24

Level I = office visit with H+E, handheld doppler Level II = duplex, plethysmography Level III = ascending, descending venography, venous pressure measurements, CTV, MRV (invasive)

Question 25

Frequency of ultrasound probe to use for venous exam in lower leg

Answer 25

4-7 MHz

Question 26

Minimum venous flow velocity before valves will close normally

Answer 26

> 30 cm/s

Question 27

Maneuvers during venous duplex exam

Answer 27

Valsalva Manual compression Deflation of pneumatic cuff with rapid < 0.3 s deflation

Question 28

Normal cutoff for retrograde venous flow

Answer 28

> 1 second is deep femoral reflex > 0.5 s for superficial vein and calf deep vein > 0.35 s for perforator ALTERNATIVELY use 0.5 sec for everything

Question 29

Minimize size of perforator veins to have valves normally

Answer 29

> 1 mm

Question 30

Size of perforator vein associated with reflux

Answer 30

> 3.5 mm (90% will reflux)