Portal pressure rises when resistance, flow, or both increase.
← LCCH Physiology
Module 03
What actually determines portal pressure — and what does TIPS change?
Move from the simple pressure-flow relationship to intrahepatic resistance, hyperdynamic splanchnic flow, HVPG, varices and the systemic consequences of creating a portosystemic shunt.
Clinical frame
The organising problem.
Portal hypertension is a haemodynamic syndrome. TIPS treats pressure by creating a low-resistance bypass, but that same bypass changes venous return, cardiac loading, hepatic perfusion and toxin delivery to the systemic circulation.
Mechanism · Gradient = flow × resistance
Start with the haemodynamic relationship
01Portal flow (Q)
02× hepatic resistance (R)
03Pressure gradient
Cirrhosis initially increases intrahepatic resistance; later splanchnic vasodilation and hyperdynamic flow further amplify portal inflow.
A pressure problem cannot be understood from anatomy alone: flow matters.
Step 1 of 6
Decompress the portal circuit. Follow the consequences.
Change resistance, inflow or the outflow route and follow each part of the system.
Increase resistance. Fibrosis and dynamic sinusoidal contraction obstruct the hepatic circuit.
- 01
Portal inflow
ReferenceUsual splanchnic flow
Selected scenarioNeed not rise initially
- 02
Hepatic resistance
ReferenceLow resistance
Selected scenarioFixed + dynamic increase
- 03
Portal gradient
ReferenceLow gradient
Selected scenarioRises for a given flow
- 04
Systemic consequence
ReferencePortal blood processed
Selected scenarioCollateral routes develop
Why this happens
A greater pressure difference is required to drive flow through a higher-resistance circuit. Portal hypertension begins with intrahepatic disease but subsequently involves the whole splanchnic circulation.
What to look for
Varices and ascites are manifestations of an altered vascular network.
Limit of the model The equation describes a relationship; it does not predict an individual HVPG from fibrosis stage.
Flow × resistance = pressure difference
All values are relative to a reference circuit. Move one control at a time.
Model pressure difference
Increasing either inflow or resistance raises the pressure difference in this fixed circuit.
Hepatic branchShunt branch
Model assumptions and limits
ΔP = Q × R. With the shunt open, 1/Rtotal = 1/Rhepatic + 1/Rshunt, using an illustrative shunt resistance of 0.5 reference units. Both routes share the same downstream pressure. Inflow is fixed at the slider setting. The model omits changes in splanchnic inflow, arterial buffering, collateral recruitment and cardiac loading. It does not calculate HVPG, stent size or a patient’s response to TIPS.
Sources and context: Baveno VII: pressure measurement ↗EASL TIPS guideline (2025) ↗
Go deeper
Mechanisms beneath the model.
Open the topics you need. Keep several explanations visible to compare mechanisms.
Evidence key: Established: broadly supported. Nuanced: context affects interpretation. Evolving: evidence or definitions remain unsettled. These labels describe physiological certainty, not a formal GRADE rating.
01HVPGWhat HVPG measures — and what it does notEstablished
HVPG is an indirect measurement of the sinusoidal portal pressure gradient and is most informative in sinusoidal portal hypertension.
- WHVP equilibrates with sinusoidal pressure when hepatic venous outflow is occluded.
- Presinusoidal disease can have clinically important portal hypertension with a normal or modest HVPG.
- Technique matters: venovenous communications and measurement artefact can mislead.
02TIPSPortal decompression is a systemic interventionEstablished
TIPS changes more than variceal pressure: it abruptly redistributes blood flow into the systemic venous circulation.
- Preload increases.
- Portal perfusion of hepatocytes falls as more blood bypasses the liver.
- Ammonia and other gut-derived substances reach the systemic circulation more directly.
03TargetHow far should pressure fall?Nuanced
For variceal bleeding, post-TIPS portosystemic pressure targets are well established; optimal gradients for ascites balance decompression against over-shunting and remain more context-dependent.
- Too little decompression risks treatment failure.
- Too much shunting can increase HE and haemodynamic stress.
- The ideal gradient depends on indication and patient reserve.
04CircuitIt is a pressure gradient across a vascular networkEstablished
The useful relationship is ΔP = Q × R: the pressure difference across a circuit depends on flow and resistance. Portal pressure itself also depends on downstream pressure. Collaterals and TIPS introduce parallel outflow routes, so the circulation cannot be reduced to one rigid tube.
- For a given inflow, a new low-resistance parallel route lowers the network’s effective resistance and changes how flow is distributed.
- The real circulation responds: splanchnic inflow, collateral flow and cardiac loading are not fixed.
- Decompression and increased systemic bypass are linked consequences. Lower portal pressure does not imply restored hepatocyte processing.
05MeasurementSubtracting downstream pressure changes the interpretationEstablished
HVPG is wedged minus free hepatic venous pressure. It estimates the sinusoidal component of portal hypertension. A high absolute hepatic venous pressure caused by systemic congestion is not equivalent to a high sinusoidal gradient.
- Presinusoidal disease can produce important portal hypertension that HVPG underestimates.
- After TIPS, the direct portal-to-systemic gradient measures decompression across the shunt circuit; it is not interchangeable with HVPG.
- Always name the pressure sites and the clinical context. Anaesthesia, vasoactive drugs and instability can affect an immediate measurement.
Interventions
What are we trying to change?
Therapy makes more sense when its physiological target is explicit. These are mechanism summaries, not prescribing guidance.
TargetPortal inflow and vascular tone
NSBB / carvedilol
Reduce portal inflow; carvedilol also lowers intrahepatic vascular resistance through alpha-1 blockade.
TargetSplanchnic inflow
Vasoactive therapy in AVB
Reduces splanchnic blood flow and portal pressure during acute variceal bleeding.
TargetPortal-systemic resistance
TIPS
Creates a low-resistance bypass that markedly lowers the portal gradient.
Apply the mechanism.
What not to conclude.
- Thinking portal hypertension is caused by resistance alone.
- Using HVPG as though it measures every form of portal hypertension.
- Viewing TIPS only as a variceal procedure rather than a systemic haemodynamic intervention.
- Ignoring cardiac reserve before major portal decompression.
Four things to keep.
- The pressure gradient across a circuit depends on flow and resistance; downstream pressure also matters.
- Advanced cirrhosis adds increased inflow to fixed and dynamic hepatic resistance.
- HVPG is a sinusoidal pressure surrogate, not a universal portal pressure measurement.
- TIPS trades portal decompression for greater systemic shunting and preload.
Evidence & current guidance
Where the physiology meets current practice.
Clinical criteria and treatment recommendations change faster than core physiology. This layer keeps the module tied to current consensus and primary evidence.
Portal hypertension is now framed around CSPH and prevention of decompensation
The latest Baveno consensus keeps clinically significant portal hypertension (CSPH) at the centre of risk stratification. In sinusoidal portal hypertension, HVPG remains the reference invasive measurement: an HVPG ≥10 mmHg defines CSPH, the range in which varices, ascites and other portal-hypertension complications become clinically relevant.
- HVPG measures the wedged hepatic venous pressure minus the free hepatic venous pressure.
- It performs best when portal hypertension is sinusoidal; presinusoidal disease can produce severe portal hypertension with a deceptively low HVPG.
- Portal pressure is not just resistance: as cirrhosis advances, increased splanchnic inflow becomes an important amplifier.
- This is why the same patient can move from a predominantly resistance problem to a resistance-plus-flow problem.
High-risk acute variceal bleeding should trigger an early TIPS decision
Baveno VIII recommends pre-emptive covered TIPS within 72 hours, ideally within 24 hours, for oesophageal or GOV1 bleeding in patients at high risk of failure despite standard vasoactive and endoscopic therapy.
- Current high-risk criteria include Child-Pugh C 10–13, Child-Pugh B >7 with active bleeding at initial endoscopy, or HVPG ≥20 mmHg at the time of bleeding.
- The rationale is not merely to stop rebleeding: avoiding treatment failure can prevent downstream organ failure and death.
- The original early-TIPS trial showed major reductions in failure/rebleeding and improved survival in selected high-risk patients.
- Baveno VIII newly states that if the preferred 72-hour window is missed, selected patients may still benefit from later TIPS — up to 2 weeks for Child C 10–13 and up to 1 week for Child B >7 with active bleeding.
After TIPS, measure the direct portosystemic gradient — not HVPG
TIPS creates a direct low-resistance connection between the portal and systemic venous circulations. Haemodynamic success is therefore assessed with the directly measured portal-to-systemic pressure gradient rather than an indirect HVPG measurement.
- For variceal bleeding, a post-TIPS portal pressure gradient <12 mmHg provides near-complete protection from portal-hypertensive rebleeding.
- A relative reduction of at least 50% from the pre-TIPS gradient is also clinically useful when considering haemodynamic response.
- The optimal gradient for recurrent/refractory ascites is less certain: excessive decompression may trade ascites control for encephalopathy or haemodynamic stress.
- Pressure should therefore be treated as a physiological target, not simply 'the lower the better'.
Portal decompression changes preload, hepatic perfusion and toxin delivery at the same time
A TIPS does more than decompress varices. It diverts portal blood away from hepatic parenchyma and into the systemic venous circulation, abruptly increasing venous return while increasing portosystemic bypass of gut-derived solutes.
- Cardiac preload rises after TIPS; occult systolic, diastolic or right-sided dysfunction can become clinically important.
- The 2025 EASL TIPS guideline recommends deliberate cardiopulmonary assessment and avoids elective TIPS in severe cardiac dysfunction, significant pulmonary hypertension and other major contraindications.
- Portosystemic shunting increases risk of overt hepatic encephalopathy, particularly in susceptible patients.
- For recurrent/refractory ascites, the physiology is a balance between portal decompression and the patient's hepatic, renal, cardiac and neurological reserve.
Not every variceal bleed should be conceptualised as the same plumbing problem
Baveno VIII distinguishes oesophageal/GOV1 bleeding from fundal gastric varices. For acute GOV2 or IGV1 bleeding, TIPS with or without variceal embolisation performed as soon as possible is now the preferred definitive option when appropriate, while transvenous obliteration and advanced endoscopic approaches remain anatomy- and expertise-dependent alternatives.
- The collateral anatomy determines whether decompression, obliteration or a combination is most logical.
- TIPS treats the driving portal pressure; embolisation/obliteration treats the collateral itself.
- Gastric and ectopic varices therefore need an anatomical as well as haemodynamic strategy.
Key sourcesPrimary guidance and landmark evidence
Reviewed 12 September 2026 · next scheduled review September 2027Baveno VIII – Advancing Consensus in Portal HypertensionBaveno VIII Faculty. J Hepatol. Published online 19 August 2026. doi:10.1016/j.jhep.2026.07.030.
Current international consensus for CSPH, prevention of decompensation, acute variceal bleeding and pre-emptive TIPS.
View source ↗EASL Clinical Practice Guidelines on TIPSEuropean Association for the Study of the Liver. J Hepatol. 2025;83:177–210. doi:10.1016/j.jhep.2025.01.029.Dedicated contemporary guidance on TIPS indications, patient selection, cardiopulmonary assessment, technical considerations and post-TIPS follow-up.
View source ↗AASLD Practice Guidance on risk stratification and management of portal hypertension and varices in cirrhosisKaplan DE, et al. Hepatology. 2024;79:1180–1211. doi:10.1097/HEP.0000000000000647.US practice guidance covering CSPH risk stratification, prevention and management of varices and portal-hypertension complications.
View source ↗Early Use of TIPS in Patients with Cirrhosis and Variceal BleedingGarcía-Pagán JC, et al. N Engl J Med. 2010;362:2370–2379. doi:10.1056/NEJMoa0910102.Landmark randomized trial establishing the clinical rationale for early/pre-emptive TIPS in selected high-risk acute variceal bleeding.
View source ↗Review policy: each module is reviewed at least annually and sooner after a major guideline, consensus statement or practice-changing study. A review date indicates editorial review, not that every linked source is open access.