Liver / TIPS (4)

Qs A patient’s right brachial pressure is 120mmhg and left is 115mmhg. The patient’s left DPA & PT are 120mmhg and 140mmHg, respectively. Their right DPA and PT are 80 and 90mmHG, respectively. Calculate their ABI.

LT : 140/120 = 1.16

RT : 90/120 = 0.75

Qs what is claudication and at what ABI value would it typically occur? what about rest pain ABI value?

claudication → pain/cramping of legs when walking

classic claudication range → 0.5-.9

rest pain → .3-.5 (<.5)

Qs When analyzing segmental pressures, look for pressure gradient changes > ______mmHg; disease is always ____________ to the cuff detecting this pressure difference

30; proximal

Qs PPG produces flow waveforms via_______, and typically applied on one’s __________.

infrared light ; digits (fingers/toes)

what is portal hypertension and its most common cause?

elevated pressures in portal venous system from impeded blood flow through the liver

caused most commonely by cirrhosis

portal hypertension leads to

varices (swollen veins)

ascites

splenomegaly

what are the indicaitons for TIPS?

refractory variceal bleeding

refractory ascites

hepatic hydrothorax

what are some symptoms of patients with portal HTN who need TIPS

GI bleeding

black stools

vomiting blood

encephalopathy (failure to detoxify liver → can cause confusion/cognitive slowing)

decreased clotting factors

ascites

what does TIPS stand for?

transjugular intrahepatic portosystemic shunt

what is TIPS?

a stented channel between a portal vein and hepatic vein

• typically RPV (posterior branch) and RHV

what kind of resistance does the TIPS shunt have?

low resistance

• diverts blood around liver

what is the hemodynamic goal of TIPS?

• redirect portal flow through the shunt

• decrease portal venous pressure

• reduct pressure gradient across liver

what are the complications of TIPS?

mechanical injury to liver

ischemic injury to liver

bleeding from procedure

recurrent vaiceal bleeding

recurring ascites/hydrothorax

worsening portal hypertension

how can we optimize color doppler when analyzing TIPS?

• adjust PRF for venous flow

• lower wall filter

• optimize gain (no noise)

• identify flow direction

what happens if color doppler is not optimized?

false stenoses

what are the required sampling sites for TIPS?

MPV (direction & wavefom)

PROX : portal end of TIPS (insertion of MPV)

MID stent

DISTAL : hepatic venous end, outflow (inserts into IVC)

portal branches if visualized

what kind of flow is expected in TIPS stent?

hepatofugal

• portal to hepatic vein

what is a normal TIPS stent velocity?

90-190 cm/s

what is the abnormal threshold for significant dysfunction of TIPS stent?

if velocity is less than 30cm/s

how does flow direction change in the MPV, LPV, RPV, Hep Art, with TIPS stent?

all vessels exhibit hepatofugal flow except the MPV (hepatopedal or bidirectional)

how will TIPS waveform appear 1 day post insertion?

early TIPS is pulsatile → takes time for pressure to equalize

• early pulsatility = shunt open and is communicating with heart

• pulsatility after weeks/months = outflow stenosis/cardiac influence

tips flow may appear pulsatile immediately after placement due to direct transmission of hepatic venous and cardiac pulsations through a newly created low resistant shunt

• eventually → hemodynamic equilibration

what are indications of TIPS failure?

thrombosis (occlusion) → absence of flow

partial thrombosis → residual flow reduced velocity

stent fibrosis → narrowing throughout stent

stenosis → site of high velocity in stent

generalized low velocity through stent

recanalization of previous varices

reduction of portal vein flow from baseline or directional change

case example

• mid TIPS velocities are 50cm/s → below normal

• distal TIPS velocities are 251 cm/s → above normal

• LPV is flowing in ‘normal direction’

  • should be hepatofugal flow with TIPS

Conclusion

• stenosis of distal TIPS

successful or unsuccessful revision of TIPS?

successful

what does this show?

• prox TIPS velocity → HIGH

• mid TIPS velocity → low

• MPV velocity → low

Conclusion : PT required a TIPS revision

• downstream stenosis reduces forward flow → velocity drops upstream

• low velocities

• direction

  • upper right image of MPV → hepatofugal flow when MPV should be hepatopetal

how do we know if TIPS is functioning properly?

• velocities in TIPS between 70-200 (or 90-190) cm/sec

• LPV flow reversed (hepatofugal)

• RPV flow reversed (hepatofugal in anterior and posterior branches)

• MPV proximal to TIPS velocity → >30cm/s

• varices recede with time

Qs A proper functional TIPS would demonstrate what kind of flow in each vessel?

LPV : hepatofugal

RPV (ant) : hepatofugal

RPV (post) : hepatofugal

MPV : hepatopetal / bidirectional

Qs A normal velocity of TIPS is?

>30

90-190 cm/s

Qs failure of TIPS dysfunction velocity is?

<30cm/s

Qs T/F : Hepatopetal flow is above the baseline

False : depends on angle

Qs How can you differentiate hepatic veins from portal veins?

waveform

• PV continuous

• HV to and fro

bmode

• PV : echogenic bright walls

case 1 :

• Recurrent ascites 6 months post-TIPS

• Focal high velocity near hepatic venous end

Diagnosis? Location? Clinical implication?

diagnosis : classic outflow stenosis

location : distal end of TIPS (hep/ivc junction)

implication : reduced effective shunt flow, rising portal pressures → explains recurrent ascites

case 2

• Recurrent variceal bleeding

• No demonstrable flow in stent

primary concern?

what must be documented before calling it?

suspected occlusion → ONLY AFTER OPTIMIZATION

• no color

• no spectral

case 3

• routine follow up

• pulsatile but patent flow

normal or abnormal?

why?

we need to know how long after the procedure this is

• normal right after TIPS procedure

• but after a couple of months portal system should adapt and pressure gradients should stabilize

  • if there is still pulsatility → outflow stenosis