Gastrointestinal: Hepatic Doppler

Question 1

What determines whether an organ has high resistance or Lowe resistance flow?

Answer 1

Organs that are “on” (e.g. brain always, muscles during exercise, bowel during digestions, etc.) should have low resistance flow, allowing those organs to be appropriately perfused

Organs that are “off” (e.g. bowel while running from a bear, muscles while sitting on the couch) should have high resistance flow, to allow blood to be redirected towards more salient organs

Question 2

How do you determine whether a vessel has low resistance or high resistance flow?

Answer 2

Look at the resistive index:

RI 0.55-0.7 (low resistance)
RI >0.7 (high resistance)

Note: To determine whether low/high resistance is abnormal you need to compare the RI to what it should be for that particular vessel.

Question 3

How do you calculate resistive index?

Answer 3

(PSV-EDV)/PSV

PSV: Peak systolic velocity
EDV: End diastolic velocity

Question 4

What is trades parvus

Answer 4

Tardus = slow systolic upstroke (i.e. prolonged acceleration time)

Parvus = decreased systolic velocity (i.e. decreased acceleration index)

Question 5

Acceleration time

Answer 5

The time from end diastole to the first systolic peak

Question 6

Acceleration index

Answer 6

The change in velocity from end diastole to the first systolic peak divided by the acceleration time

(PSV-EDV)/AT

Note: This is a combined measure of how quickly and drastically a vessel can increase blood flow. Bigger PSV-EDV differences and shorter acceleration times will lead to an increased acceleration index.

Question 7

What defines being upstream to a stenosis?

Answer 7

Being proximal to a stenosis (upstream blood has not yet traversed the stenosis)

Question 8

Direct signs of stenosis

Answer 8

• Elevated PSV
• Spectral broadening

Question 9

Indirect signs of stenosis

Answer 9

• Downstream trades parvus
• High RI upstream and low RI downstream

Question 10

Which direction is the blood flowing in this hepatic vein spectral Doppler?

Answer 10

Majority is flowing antegrade (towards the heart), which is normal

Note: Note above the line is retrograde (towards the liver) and below the line is antegrade (towards the heart).

Question 11

What are the major categories of pathology that alter hepatic vein waveforms?

Answer 11

• Pressure changes in the right heart (e.g. CHF, tricuspid regurgitation)
• Direct compression of hepatic veins (e.g. cirrhosis)

Question 12

What does the “a” wave represent in the hepatic vein waveform?

Answer 12

Atrial contraction

Question 13

How do right atrial pressures affect the A wave in the hepatic vein waveform?

Answer 13

Anything that increases right atrial pressures will cause the A wave to slope upward

Anything that decreases right atrial pressures will cause the A wave to slope downward

Question 14

What are the major categories of hepatic vein waveform abnormalities?

Answer 14

• Increased pulsatility
• Decreased pulsatility
• Absent waveform

Question 15

Common causes of increased pulsatility of the hepatic vein waveform

Answer 15

• Tricuspid regurgitation
• Right-sided heart failure

Question 16

Common causes of decreased pulsatility of the hepatic vein waveform

Answer 16

• Cirrhosis
• Hepatic venous outflow obstruction (e.g. hepatic venoocclusive disease, IVC obstruction)

Question 17

Common causes of absent hepatic veinous waveform

Answer 17

Budd-Chiari (hepatic vein thrombosis)

Question 18

How can you differentiate tricuspid regurgitation from right heart failure on hepatic vein waveform?

Answer 18

Both have increased hepatic vein pulsatility, but in tricuspid regurgitation the D wave will be lower than the S wave

Note: The D wave will be higher than the S wave in right heart failure.

Question 19

Why can you see some cardiac variability in the pulsatility of the portal vein?

Answer 19

Some cardiac variability can be transmitted from the hepatic veins to the portal veins normally (via the hepatic sinusoids)

Question 20

What is the normal velocity of the portal vein?

Answer 20

20-40 cm/s

Question 21

What are the three main categories of findings on portal vein spectral Doppler?

Answer 21

• Normal (steady flow above baseline, hepatopetal)
• Pulsatile flow
• Reversed flow (steady flow below baseline, hepatofugal)
• Absent flow

Question 22

What are the major causes of portal vein pulsatility?

Answer 22

• Right sided heart failure
• Tricuspid regurgitation
• Cirrhosis (with vascular AP shunting)

Question 23

What are the main causes of reversed portal vein flow?

Answer 23

Portal hypertension (e.g. cirrhosis, budd-chiari, CHF, etc.)

Question 24

What are the main causes of absent portal veinous flow?

Answer 24

• Portal vein thrombosis
• Tumor invasion of the portal vein
• Stagnant flow (due to severe portal hypertension)

Question 25

When should you consider portal vein flow to be slow?

Answer 25

Portal vein velocities less than 15 cm/s

Question 26

Common causes of slow portal vein flow

Answer 26

• Portal hypertension (most common)
• Prehepatic (e.g. portal vein thrombosis)
• Intrahepatic (e.g. cirrhosis)
• Posthepatic (e.g. Right heart failure, tricuspid regurgitation, Budd-Chiari)