Circulation StudioCardiovascular simulation

Pulmonary hypertension

Reviewed 2026-10-30
Resources
Introduction to the module

Understand the pressure.

Connect catheter physiology with diagnosis and treatment. Explore a demonstration, or work through the clinical chapters.

Follow the pressure through the pulmonary circulationBlood moves from the right ventricle through branching lung vessels to the left atrium. Cardiac output is flow, mean pulmonary artery pressure is the upstream pressure, pulmonary vascular resistance is the resistance across the lung vessels, and wedge pressure estimates downstream pressure when measured appropriately. The selected driver is vascular resistance. The lung and chamber outlines are conceptual, not anatomical or quantitative patient measurements.FOLLOW THE CIRCULATIONRVRight ventriclePVRLung vesselsLALeft atriummPAPPA pressureCOForward flowPAWPConceptual circuit · chamber positions and vessel sizes are illustrative
mPAPPAWPCO × PVR

Pulmonary vascular resistance is the pressure difference across the lung circulation divided by cardiac output.

Chapter 1 of 15

One pressure syndrome. Five different mechanisms.

Start with pulmonary hypertension, establish the hemodynamic phenotype, then identify the predominant disease mechanism. PAH is one subgroup of PH.

VISUAL EXPLANATION

Pressure has three drivers.

Pressure has three drivers.Pulmonary pressure reflects downstream pressure, forward flow and vascular resistance. Original conceptual schematic, not patient imaging or a quantitative model.FOLLOW BLOOD FROM RIGHT TO LEFTRVThe pumpCOPVRLung vesselsLAPAWPmPAP = PAWP + CO × PVRDownstream pressure + flow × resistance
Original conceptual schematic · not patient imaging.

  1. PH is the pressure syndrome. PAH is one specific clinical diagnosis.

  2. Read mPAP, PAWP and cardiac output together. Calculate PVR.

  3. Most PH comes from left heart or lung disease.

Humbert M, Kovacs G, Hoeper MM, et al · 2022Kovacs G, Bartolome S, Denton CP, et al · 2024
Explore the chapter
RHCPH phenotypeClinical diagnosis

PH is a finding; PAH is a diagnosis

Pulmonary hypertension (PH) is a resting mean pulmonary artery pressure (mPAP) >20 mmHg measured by right heart catheterization (RHC). Pulmonary arterial hypertension (PAH) is group 1 disease: a compatible clinical phenotype with pre-capillary hemodynamics after alternative explanations, including left heart disease, significant lung disease and chronic thromboembolic disease, have been assessed. An elevated echo RVSP alone establishes neither PH nor PAH.

  • Pre-capillary PH: mPAP >20 mmHg, PAWP ≤15 mmHg and PVR >2 Wood units (WU).
  • Isolated post-capillary PH: mPAP >20 mmHg, PAWP >15 mmHg and PVR ≤2 WU.
  • Combined post- and pre-capillary PH: mPAP >20 mmHg, PAWP >15 mmHg and PVR >2 WU.
  • Elevated mPAP with PAWP ≤15 and PVR ≤2 WU is an unclassified hemodynamic pattern; consider high pulmonary flow and investigate the cause.
Humbert M, Kovacs G, Hoeper MM, et al · 2022Kovacs G, Bartolome S, Denton CP, et al · 2024
PopulationRegistriesAssociated disease

Who develops PH?

Population estimates depend on age, geography, ascertainment and the pressure threshold used. PH overall affects approximately 1% of the population; groups 2 and 3 account for the great majority. In contemporary registries from economically developed countries, PAH incidence is approximately 6 per million adults per year and prevalence approximately 48–55 per million adults. The classic young female presentation remains important, but many contemporary patients are older with cardiac or pulmonary comorbidities.

  • Idiopathic PAH is common within PAH registries; connective tissue disease, congenital heart disease and portal hypertension are major associated conditions.
  • Women develop PAH more often, yet sex, age, cause, comorbidity and RV adaptation all influence prognosis.
Supporting detail1 more point
  • Globally, rheumatic and other left heart disease, chronic lung disease, congenital heart disease, HIV and schistosomiasis contribute different burdens. Registry estimates should not be transferred uncritically across settings.
Humbert M, Kovacs G, Hoeper MM, et al · 2022Kovacs G, Bartolome S, Denton CP, et al · 2024Hassoun PM · 2021
FlowWedge pressureResistance

How the pressure rises

The pulmonary circulation normally carries the entire cardiac output at low resistance. Mean pulmonary artery pressure reflects flow, downstream left atrial pressure and pulmonary vascular resistance: mPAP ≈ PAWP + cardiac output × PVR. A pressure rise can therefore come from increased flow, increased left heart filling pressure, pulmonary vascular obstruction/remodeling, or several of these together.

  • PVR = (mPAP − PAWP) / cardiac output; pressure in mmHg and flow in L/min produce WU.
  • PVR captures steady load. Reduced pulmonary arterial compliance adds pulsatile load that a single resistance value misses.
Supporting detail1 more point
  • A falling pulmonary pressure can accompany improving afterload or a failing RV with falling output; inspect cardiac output, RAP, SvO₂ and the clinical state.
Humbert M, Kovacs G, Hoeper MM, et al · 2022Hemnes AR, Celermajer DS, D’Alto M, et al · 2024
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