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OverviewAetiologyPathophysiologyClinical features and red flagsInvestigationsDifferential diagnosisManagementComplicationsMonitoring and follow-upSpecial situationsCommon pitfallsQuestionsSources
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Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.

Pulmonary hypertension

Cardiology · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

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Time-critical presentation

Syncope, hypotension, rising lactate, severe hypoxaemia, new arrhythmia or right-heart failure in pulmonary hypertension is a high-mortality emergency; avoid large unassessed fluid boluses and seek immediate PH-centre/critical-care advice.

Overview

Recognise pulmonary hypertension early, classify its cause correctly and refer suspected PAH or CTEPH to nationally commissioned specialist care.

PH is a haemodynamic state with five broad groups: PAH; PH due to left-heart disease; lung disease/hypoxia; pulmonary artery obstruction including CTEPH; and unclear/multifactorial mechanisms. Treatments differ fundamentally by group.

Symptoms reflect limited RV reserve and are often nonspecific. Referral should accelerate when there is exertional syncope, rapid progression, RV dysfunction, suspected PAH or evidence of chronic thromboembolism.

Key points

  • Pulmonary hypertension is haemodynamically defined by mean pulmonary artery pressure greater than 20 mmHg at rest on right-heart catheterisation.
  • Pre-capillary PH also requires pulmonary artery wedge pressure 15 mmHg or less and pulmonary vascular resistance greater than 2 Wood units.
  • Echo estimates probability; it does not confirm PH or distinguish all five clinical groups.
  • Use a three-step approach: clinical suspicion, echocardiographic detection, then confirmation/classification in a PH centre.
  • Always consider left-heart disease, lung/hypoxic disease and chronic thromboembolic PH before labelling PAH.
  • A ventilation-perfusion scan is the key screening test for CTEPH; a normal perfusion scan makes it unlikely.
  • PAH-targeted drugs should be initiated and escalated by a specialist PH service, generally using risk-based combination therapy.

Aetiology

01

Pulmonary arterial hypertension

Idiopathic, heritable or drug-associated disease, connective-tissue disorders, portal hypertension, HIV and congenital shunts can remodel small pulmonary arteries and raise precapillary vascular resistance.

02

Left-heart disease

Left-ventricular dysfunction, impaired relaxation or valve disease can raise left-atrial and pulmonary venous pressure, producing post-capillary pulmonary hypertension and sometimes secondary vascular remodelling.

03

Lung disease and hypoxia

Chronic parenchymal lung disease can reduce the pulmonary vascular bed, while sustained hypoxia, including from some sleep-related breathing disorders, drives vasoconstriction and may promote vascular remodelling.

04

Chronic pulmonary arterial obstruction

Organised thromboembolic material can obstruct pulmonary arteries after venous thromboembolism. Other multifactorial conditions may also elevate pressure through combined vascular, cardiac and systemic mechanisms.

Pathophysiology

  1. 1
    Pulmonary vascular load develops

    Vascular remodelling, hypoxic constriction, chronic obstruction or transmitted left-atrial pressure can increase the pressure required from the right ventricle to eject blood.

  2. 2
    Right-ventricular adaptation

    The right ventricle initially hypertrophies and increases contractility to preserve stroke volume against the higher afterload, often masking symptoms until cardiovascular reserve becomes limited.

  3. 3
    Maladaptation and dilatation

    Persistent load may eventually cause right-ventricular dilatation, ischaemia and reduced contractility. Annular enlargement can add functional tricuspid regurgitation and further volume stress.

  4. 4
    Ventricular interaction

    A dilated, pressure-loaded right ventricle displaces the interventricular septum, reducing left-ventricular filling and systemic cardiac output, particularly during exertion when demand rises.

  5. 5
    Systemic congestion and low output

    Falling forward flow causes fatigue, syncope and hypotension, while rising systemic venous pressure produces oedema, ascites and congestive renal or liver dysfunction.

Clinical features and red flags

Early symptoms

Progressive exertional dyspnoea, fatigue, reduced exercise capacity, chest pressure or palpitations without a sufficient alternative explanation.

Right-heart signs

Loud P2, RV heave, tricuspid regurgitation murmur, raised JVP, hepatomegaly, ascites and oedema.

High-risk presentationRed flag

Exertional syncope, hypotension, WHO functional class IV symptoms or rapidly worsening right-heart failure.

Cause clues

Connective-tissue disease, portal hypertension, HIV, congenital shunt, appetite-suppressant/toxin exposure, lung disease or prior PE should direct classification.

CTEPH clue

Persistent dyspnoea after PE, mismatched perfusion defects or chronic thromboembolic signs on CT warrants expert operability assessment.

Investigations

  1. 01
    ECG, chest radiograph and basic blood testsFirst step
    Why
    Look for RV strain, alternative disease, anaemia, renal/liver dysfunction, thyroid disease and treatment constraints.
    Interpretation and limitations
    Normal ECG does not exclude mild PH; advanced RV strain increases concern.
  2. 02
    BNP or NT-proBNP
    Why
    Assess RV wall stress and prognosis.
    Interpretation and limitations
    Interpret with age, renal function and rhythm; use trends within a validated risk model rather than a single diagnostic cutoff.
  3. 03
    Transthoracic echocardiography
    Why
    Estimate PH probability and assess RV/LV, valves and congenital shunts.
    Interpretation and limitations
    Use tricuspid-regurgitation velocity plus additional signs; an estimated pressure alone is insufficient.
  4. 04
    Pulmonary function tests, arterial gases and chest CT
    Why
    Identify parenchymal lung disease, hypoxia and other thoracic causes.
    Interpretation and limitations
    A disproportionately low gas transfer can support pulmonary vascular disease but is not specific.
  5. 05
    Ventilation-perfusion scan
    Why
    Screen for CTEPH in newly diagnosed or unexplained PH.

Differential diagnosis

01

Left-sided heart failure

Left-atrial enlargement, ventricular or valve abnormalities and raised filling pressure favour left-heart disease; specialist catheter measurements separate this from a precapillary pulmonary arterial phenotype.

02

Parenchymal lung disease

Prominent airflow limitation, abnormal gas transfer and characteristic chest imaging favour chronic lung disease, although pulmonary hypertension may coexist when vascular burden is disproportionate.

03

Chronic thromboembolic disease

Previous embolism and mismatched perfusion defects suggest chronic thromboembolic pulmonary hypertension; a normal perfusion study makes this mechanism substantially less likely.

04

Anaemia or thyroid disease

Fatigue, breathlessness and palpitations may arise from systemic illness; blood tests identify these contributors, while right-heart signs and vascular imaging support pulmonary hypertension.

05

Coronary disease or deconditioning

Exertional chest pressure or breathlessness may reflect myocardial ischaemia or poor conditioning. These can coexist with pulmonary hypertension, so right-heart or pulmonary-vascular abnormalities still need an explanation.

Management

01FirstClinical suspicionFirst stepUnexplained dyspnoea, syncope, RV signs or a condition associated with PAH/CTEPH.+
  1. 1Assess acuity, oxygen saturation, ECG, chest radiograph, FBC, renal/liver/thyroid tests and BNP/NT-proBNP.
  2. 2Obtain expert echocardiography to grade PH probability and examine left heart, RV and shunts.
  3. 3Investigate common causes with lung testing/imaging and a V/Q scan rather than assuming idiopathic PAH.
  4. 4Refer intermediate/high echo probability, suspected PAH or CTEPH to an NHS specialist PH centre.
02NextConfirm and classifySpecialist evaluation for likely PH.+
  1. 1Complete cause-specific serology, imaging, functional assessment and congenital/portal/HIV evaluation as indicated.
  2. 2Perform right-heart catheterisation with accurate zeroing, wedge pressure and cardiac output measurement.

Complications

01

Progressive right-sided heart failure

Sustained afterload may eventually exhaust right-ventricular compensation, causing venous congestion, oedema, ascites, hepatic discomfort and repeated decompensation with a worsening prognosis.

02

Functional tricuspid regurgitation

Right-ventricular and annular dilatation prevent leaflet coaptation. Regurgitant volume then aggravates chamber enlargement, systemic venous pressure and congestive symptoms of right-sided failure.

03

Arrhythmia

Right-atrial stretch and chamber remodelling predispose to atrial tachyarrhythmias, which reduce filling and output and can precipitate abrupt clinical deterioration.

04

Syncope, shock and sudden death

A failing right ventricle cannot increase output during exertion or acute stress. Systemic hypotension may impair right-coronary perfusion, creating a spiral towards shock or arrest.

05

Congestive organ dysfunction

Persistently raised venous pressure impairs renal filtration and causes hepatic congestion, while low output further compromises organ perfusion and complicates fluid management.

Monitoring and follow-up

  • At specialist reviews, record WHO functional class, syncope, right-heart-failure signs and treatment adherence.
  • Trend 6-minute walk or cardiopulmonary exercise capacity, BNP/NT-proBNP and RV imaging within a risk model.
  • Monitor blood pressure, oxygenation, weight/volume status, renal/liver function and medicine-specific laboratory tests.
  • Repeat haemodynamics when clinical response is unclear, before major escalation or as the PH centre recommends.
  • Review contraception/pregnancy risk, anticoagulation indication, vaccinations, exercise and emergency contact plan.

Special situations

Echo is a probability test

Right-heart catheterisation establishes the diagnosis and separates pre- from post-capillary physiology.

V/Q before reassurance

CT pulmonary angiography can miss chronic distal disease; V/Q scanning remains the screening test for CTEPH.

Treat the group

PAH drugs are not routine therapy for PH caused by left-heart or lung disease and may cause harm.

The RV drives prognosis

Symptoms, natriuretic peptides and outcomes reflect the ability of the RV to adapt to afterload.

Never stop prostacyclin abruptly

Interruption of continuous epoprostenol or treprostinil can cause rapid rebound PH and collapse.

Common pitfalls

  1. 01

    Diagnosing PH from an echo-estimated systolic pressure alone.

  2. 02

    Starting PAH-targeted therapy before right-heart catheterisation and classification.

  3. 03

    Failing to obtain a V/Q scan when CTEPH is possible.

  4. 04

    Giving large empiric fluid boluses in decompensated RV failure.

  5. 05

    Combining sildenafil with nitrates or riociguat.

Practice

Two practice questions

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Question 1 of 2
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CardiologyOriginal SBA

Haemodynamic definition

During investigation of unexplained breathlessness, which right-heart-catheter finding fulfils the current haemodynamic definition of pulmonary hypertension?

Choose one answer, then submit
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Sources and review status5 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • ESC/ERS 2022 pulmonary hypertension guidelineDefinition, diagnosis, classification and treatment.
  • European Respiratory Journal full guidelineOfficial joint ESC/ERS guideline text.
  • NHS England specialised respiratory servicesAdult PH centres and commissioned services.
  • Riociguat SmPCCTEPH/PAH dose, titration and contraindications.
  • Sildenafil PAH SmPCAdult PAH dosing and safety.

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateComplete draftClinical stateAwaiting reviewJurisdictionUnited Kingdom
Interpretation and limitations
Mismatched perfusion defects require CTEPH-centre imaging and operability review.
  • 06
    Right-heart catheterisation
    Why
    Confirm PH, measure PAWP/PVR/cardiac output and classify haemodynamics.
    Interpretation and limitations
    Required before PAH-specific treatment; vasoreactivity testing is reserved for idiopathic, heritable or drug-associated PAH in expert centres.
  • 3Classify pre- versus post-capillary physiology and assign the clinical PH group.
  • 4For CTEPH, obtain multidisciplinary pulmonary endarterectomy, balloon angioplasty and medical-therapy assessment.
    • 03TreatmentRisk-based specialist therapyConfirmed PAH or CTEPH after classification.+
    1. 1Optimise oxygenation, volume status, exercise/rehabilitation, vaccination and the underlying condition.
    2. 2For PAH, use guideline risk assessment to select initial oral combination therapy or parenteral prostacyclin-based treatment in high risk.
    3. 3Reassess early using symptoms, WHO class, 6-minute walk distance, biomarkers, RV imaging and haemodynamics when needed.
    4. 4EscalationEscalate combination therapy and consider transplantation if a low-risk profile is not achieved.
    04EscalationAcute right-heart failureEscalationSyncope, hypotension, rising lactate, oliguria, severe congestion or arrhythmia.+
    1. 1Admit to critical care with immediate PH-centre involvement and search for infection, PE, anaemia, arrhythmia and treatment interruption.
    2. 2Maintain systemic pressure and RV perfusion; use carefully titrated diuresis for congestion and avoid indiscriminate fluid loading.
    3. 3Continue established PAH therapy and never abruptly interrupt a prostacyclin infusion.
    4. 4EscalationEscalate inotropes/vasopressors, inhaled pulmonary vasodilators or mechanical/transplant support through the expert team.
    Key medicines and prescribing safety4 treatments · regimens, roles and cautions+
    PDE-5 inhibitor used in specialist PAH combination strategies.

    Sildenafil

    20 mg orally three times daily for PAH.

    Contraindicated with nitrates and riociguat; hypotension, visual effects and CYP3A interactions.

    Endothelin-receptor antagonist for selected PAH, including congenital-shunt-associated disease.

    Bosentan

    62.5 mg orally twice daily for 4 weeks, then 125 mg twice daily if tolerated.

    Teratogenic; monthly liver tests, haemoglobin monitoring and major drug interactions including reduced hormonal-contraceptive reliability.

    Endothelin-receptor antagonist for long-term PAH treatment, alone or in combination.

    Macitentan

    10 mg orally once daily.

    Specialist initiation; teratogenicity, anaemia, oedema and liver assessment. Ensure effective pregnancy prevention.

    Specialist treatment for inoperable or persistent/recurrent CTEPH after operability assessment, and selected PAH.

    Riociguat

    Start 1 mg orally three times daily for 2 weeks. If systolic BP is at least 95 mmHg without hypotensive symptoms, increase by 0.5 mg three times daily every 2 weeks to a maximum 2.5 mg three times daily; reduce by 0.5 mg three times daily if systolic BP falls below 95 mmHg with symptoms.

    Do not combine with PDE-5 inhibitors or nitrates and do not start when systolic BP is below 95 mmHg. Contraindicated in pregnancy and severe hepatic impairment; not recommended when creatinine clearance is below 30 mL/min. Smoking lowers exposure, so starting or stopping smoking can require specialist dose review.