Chronic thromboembolic pulmonary hypertension

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

After embolic material fails to resolve, fibrotic webs, bands, pouch lesions and occlusions can obstruct pulmonary arteries. Flow is redirected to unobstructed vessels, and secondary microvascular disease raises pulmonary vascular resistance. The right ventricle initially adapts, then dilates and fails. Symptom severity reflects haemodynamics and right-ventricular reserve more than clot volume alone.

CTEPH is an important diagnosis because its treatment differs from other pulmonary hypertension. Pulmonary endarterectomy removes organised material from accessible vessels and offers the best chance of normalising haemodynamics. Anatomical distribution, pulmonary vascular resistance, comorbidity and centre expertise determine operability; a single non-specialist opinion or apparent distal disease on routine CT should not close the surgical route.

Referral is to a designated pulmonary-hypertension service, with national expert assessment for endarterectomy and balloon pulmonary angioplasty. Care differs across UK nations and commissioned services; targeted therapy and operability require current national policy and a specialist MDT decision.

Key points

CTEPH is persistent organised thromboembolic obstruction with pulmonary vascular remodelling and pulmonary hypertension; it is not simply residual clot visible after an acute pulmonary embolism.
Suspect it when breathlessness, exercise limitation, syncope or right-heart signs persist after pulmonary embolism, but remember that some patients have no documented acute embolic event.
A normal or mildly abnormal chest radiograph and nonspecific ECG do not exclude significant disease.
Transthoracic echocardiography estimates probability and right-heart impact; it does not confirm haemodynamics or define operability.
Ventilation–perfusion scanning is a sensitive screening test for chronic thromboembolic obstruction. A routine CTPA reported as negative for acute PE may miss chronic distal disease.
Right-heart catheterisation confirms the haemodynamic phenotype, while high-quality pulmonary vascular imaging maps disease for treatment decisions.
Every confirmed patient should be assessed by a specialist CTEPH multidisciplinary team for pulmonary endarterectomy, regardless of age alone or initial local assumptions about operability.
Pulmonary endarterectomy can be curative in operable disease; balloon pulmonary angioplasty and specialist drug therapy are options for selected inoperable, persistent or recurrent disease.
Therapeutic anticoagulation is generally long term, but agent choice is individualised by the specialist team, antiphospholipid status, bleeding risk, pregnancy and comorbidity.
Exact targeted-therapy eligibility is commissioning- and jurisdiction-dependent; NHS England updated its adult pulmonary-hypertension targeted-therapy policy in July 2026.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Unresolved pulmonary emboli

Organised thromboembolic material persists after recognised or silent embolism and becomes incorporated into proximal or segmental pulmonary arteries.

Recurrent thromboembolism

Ongoing venous thrombotic risk, previous embolism and some prothrombotic disorders increase the opportunity for cumulative vascular obstruction.

Associated conditions

Splenectomy, infected intravascular devices, chronic inflammatory disease and selected haematological conditions are associated with increased CTEPH risk.

Individual vascular response

Only a minority of people with acute embolism develop CTEPH, indicating variable clot resolution, endothelial response and small-vessel remodelling.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Fibrotic arterial obstruction
Thrombus organises into webs, bands and occlusions that mechanically reduce the cross-sectional area of the pulmonary circulation.
2
Redistributed blood flow
Unobstructed vessels receive excess flow and pressure, promoting secondary arteriopathy in smaller pulmonary arteries, thereby altering ventilation, gas transfer or respiratory mechanics.
3
Rising pulmonary resistance
Mechanical obstruction and microvascular remodelling progressively increase right-ventricular afterload and limit cardiac-output augmentation during exercise, thereby altering ventilation, gas transfer or respiratory mechanics.
4
Right-heart failure
Chronic pressure overload causes right-ventricular hypertrophy, dilation and eventual failure, producing exertional syncope, oedema and low output.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Persistent post-PE limitation

Breathlessness, fatigue, chest discomfort, exercise desaturation or syncope beyond expected recovery after adequate acute-PE treatment should trigger structured assessment rather than being labelled deconditioning.

Previously unrecognised CTEPH

Progressive exertional limitation with a loud pulmonary component, right-ventricular heave, raised JVP or oedema may occur without known PE; prior venous thrombosis, splenectomy, inflammatory disease and chronic intravascular devices increase suspicion.

Right-heart decompensationRed flag

Rest symptoms, syncope, hypotension, rising JVP, cool peripheries, hepatic congestion, renal dysfunction or escalating oxygen requirement indicate advanced disease and require urgent specialist assessment.

Chronic thromboembolic imaging pattern

Eccentric wall-adherent material, webs, bands, abrupt narrowing, pouch defects, mosaic perfusion and enlarged bronchial arteries support chronic rather than acute thromboembolism.

Recurrent acute embolismRed flag

New pleuritic pain, haemoptysis, tachycardia or acute hypoxaemia during follow-up may represent recurrent PE despite treatment and needs immediate reassessment of adherence, interaction, absorption and thrombosis drivers.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
ECG, chest radiograph and baseline blood testsFirst step
Why
Identify right-heart strain, competing lung or cardiac disease and consequences of congestion.
Interpretation and limitations
Findings may be normal early. Anaemia, thyroid disease and renal or liver dysfunction can worsen symptoms and influence anticoagulation or intervention.
02
Transthoracic echocardiography
Why
Estimate pulmonary-hypertension probability and assess right-ventricular size, function and alternative cardiac causes.
Interpretation and limitations
An estimated pressure is not a definitive diagnosis; poor tricuspid signal does not exclude disease. Right-ventricular dysfunction or pericardial effusion increases urgency.
03
Ventilation–perfusion scan
Why
Screen sensitively for persistent mismatched perfusion defects compatible with chronic thromboembolic obstruction.
Interpretation and limitations
A normal perfusion study makes CTEPH unlikely. Multiple segmental mismatched defects require specialist pulmonary vascular imaging, not automatic treatment as acute PE.
04
CT pulmonary angiography with chronic-thromboembolic expertise
Why
Define vascular morphology, lung parenchyma, mediastinum and possible surgical anatomy.
Interpretation and limitations
Routine acute-PE protocols and reporting may miss webs or distal lesions. A negative local CTPA should not overturn a strongly abnormal V/Q scan.
05
Right-heart catheterisation
Why
Confirm pulmonary-hypertension haemodynamics, separate pre- from post-capillary disease and measure severity.
Interpretation and limitations
Interpret pressures, cardiac output and resistance at a designated centre after excluding major reversible confounders; catheter data alone do not decide operability.
06
Pulmonary angiography and multidisciplinary imaging review
Why
Map endarterectomy or balloon-angioplasty targets and integrate anatomical and haemodynamic burden.
Interpretation and limitations
Operability depends on accessible disease relative to resistance and patient factors. It is an expert-team judgement, not a single vessel-size cutoff.
07
Functional assessment with walk testing or cardiopulmonary exercise testing
Why
Quantify limitation, establish baseline risk and monitor treatment response.
Interpretation and limitations
Interpret distance, symptoms, oxygenation and haemodynamics together; a preserved walk distance does not exclude important early disease.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Pulmonary arterial hypertension

Pre-capillary pulmonary hypertension without chronic perfusion defects or organised thrombus suggests another pulmonary vascular group and different definitive treatment.

Left-heart disease

Elevated left-sided filling pressure, valve disease or ventricular dysfunction indicates post-capillary pulmonary hypertension rather than isolated CTEPH.

Chronic lung disease

Emphysema, fibrosis or sleep-related hypoventilation with matching physiological and imaging burden may better explain pulmonary hypertension and breathlessness.

Deconditioning after PE

Persistent symptoms with normal pulmonary haemodynamics and no chronic perfusion defects may reflect deconditioning, anxiety or another cardiopulmonary diagnosis.

Pulmonary artery tumour

An enlarging unilateral intraluminal mass or atypical metabolic and imaging behaviour raises rare pulmonary artery sarcoma rather than organised clot.

Additional chapter-specific clues

Alternative pulmonary hypertension group

Left-heart disease, parenchymal lung disease, hypoventilation, portal hypertension, connective-tissue disease or congenital heart disease may explain raised pulmonary pressures and require a different pathway.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01DetectionPersistent symptoms after pulmonary embolismFirst stepBreathlessness, syncope or exercise limitation fails to improve as expected after treated PE.

1Confirm anticoagulant adherence, dose appropriateness, interactions and whether a new acute PE or another cardiopulmonary diagnosis is present.
2Obtain ECG, chest radiograph, echocardiography and baseline physiology, then arrange V/Q scanning when CTEPH remains possible.
3Refer abnormal perfusion or convincing clinical findings to a designated pulmonary-hypertension centre rather than repeating nonspecialist CT alone.
4EscalationEscalate urgently for right-heart decompensation, syncope or rapid deterioration.

02ConfirmationSpecialist haemodynamic and anatomical work-upMismatched perfusion defects or imaging and echocardiographic evidence suggest CTEPH.

1Continue therapeutic anticoagulation unless the specialist procedural plan requires controlled interruption.
2Use expert CTPA, right-heart catheterisation and, where required, catheter pulmonary angiography to define disease and severity.
3Exclude or quantify left-heart disease, parenchymal lung disease and other contributors to symptoms and pulmonary pressure.
4Discuss all data in a specialist CTEPH MDT with access to endarterectomy, balloon angioplasty and targeted therapy.

03Definitive treatmentChoose endarterectomy before palliationDefinitiveCTEPH has been confirmed and the patient can consider intervention.

1Refer every potentially suitable patient for expert pulmonary endarterectomy assessment; do not deny surgery based on age or local imaging alone.
2If operable, optimise anticoagulation and right-heart status and proceed through the national surgical pathway with informed discussion of benefits and risks.
3If inoperable or with residual disease, assess balloon pulmonary angioplasty and commissioned targeted therapy at the specialist centre.
4Reassess haemodynamics, function and symptoms after intervention because residual or recurrent pulmonary hypertension changes follow-up.

04DecompensationProtect the failing right ventricleEscalationHypotension, syncope, worsening congestion, low output or escalating hypoxaemia.

1Use monitored ABCDE care, controlled oxygen for hypoxaemia and immediate specialist/critical-care discussion.
2Identify triggers including arrhythmia, infection, anaemia, recurrent PE, medication interruption and excessive fluid or diuresis.
3Use cautious, response-guided diuresis for congestion and avoid indiscriminate fluid boluses that worsen right-ventricular dilation.
4Coordinate vasoactive, ventilatory and rescue-intervention decisions with pulmonary-hypertension and critical-care experts.

Key medicines and prescribing safety4 treatments · regimens, roles and cautions

Prevents recurrent venous thromboembolism while definitive obstruction and pulmonary vascular disease are addressed.

Long-term therapeutic anticoagulation

Use an individually selected full-treatment regimen continuously, verified against the current BNF, renal function, interactions and specialist CTEPH plan.

Do not assume every direct oral anticoagulant suits antiphospholipid syndrome, pregnancy, severe renal disease or planned procedures. Interruption requires a documented specialist plan.

Targets soluble guanylate cyclase signalling in selected inoperable CTEPH or persistent or recurrent pulmonary hypertension after surgery.

Riociguat

Initiated and titrated only by a designated pulmonary-hypertension centre under the current NHS commissioning policy and product information.

Causes hypotension and is contraindicated in pregnancy; reliable contraception and pregnancy testing are required where relevant. Never combine with PDE5 inhibitors or nitrates, and check smoking-related pharmacokinetic effects.

Relieves oedema, ascites and venous congestion without treating the obstructive cause.

Loop diuretic for right-heart congestion

Use a specialist-led oral or intravenous regimen titrated to congestion, renal function, blood pressure and prior diuretic exposure.

Excess diuresis can reduce right-ventricular preload and cardiac output. Monitor weight, urine output, creatinine, sodium, potassium and symptoms closely.

Corrects hypoxaemia and may reduce secondary hypoxic pulmonary vasoconstriction.

Supplemental oxygen

Prescribe to a documented target when hypoxaemia is present, following BTS and local oxygen pathways rather than for breathlessness alone.

Oxygen does not replace endarterectomy assessment or other definitive therapy. Consider hypercapnic risk and arrange formal long-term oxygen assessment if stable hypoxaemia persists.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Progressive right-heart failure

Sustained afterload causes systemic venous congestion, hepatic and renal dysfunction, low cardiac output and worsening exercise capacity.

Syncope and sudden deterioration

Inability to increase output during exertion can cause syncope, while arrhythmia or further embolism may trigger abrupt decompensation.

Chronic hypoxaemia

Uneven perfusion, reduced mixed venous oxygen and low output contribute to exertional and later resting hypoxaemia.

Inoperable microvascular disease

Extensive distal remodelling may persist despite removal of accessible obstruction and limit the haemodynamic benefit of intervention.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Track WHO functional class, syncope, chest pain, signs of congestion, blood pressure, oxygen saturation and patient-reported activity at every review.
Use specialist follow-up with exercise capacity, natriuretic peptide, echocardiographic right-heart measures and haemodynamics when they will change management.
Monitor anticoagulation adherence, bleeding, renal and liver function, interacting medicines and procedure plans continuously.
After endarterectomy or balloon angioplasty, look for reperfusion injury early and residual pulmonary hypertension later using the centre protocol.
For targeted therapy, follow centre-specific blood pressure, laboratory, pregnancy-prevention and adverse-effect monitoring; primary care must not alter treatment independently.
Reassess new deterioration for recurrent PE, arrhythmia, infection, anaemia or left-heart disease rather than assuming inevitable progression.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

V/Q remains central

A technically adequate normal perfusion scan is powerful negative evidence. CTPA adds anatomy but routine acute-PE reporting can miss chronic webs, bands and distal obstruction.

Operability is not a radiology adjective

Disease accessibility must be weighed against haemodynamics, comorbidity and surgical expertise by the national CTEPH team. “Distal” on a local report should not end referral.

No remembered PE is common

CTEPH may follow an unrecognised embolic event. Absence of a documented acute PE should not block investigation when perfusion and right-heart findings fit.

Do not treat the echo number

Echo estimates probability and right-heart effect. Right-heart catheterisation is required to classify haemodynamics before targeted treatment.

Pregnancy needs preconception expertise

Pulmonary hypertension carries major maternal risk and riociguat is contraindicated. Discuss reproductive intentions early with the designated PH and maternal-medicine teams.

11Common pitfallsFrequent interpretation and management errors.

01
Calling persistent post-PE breathlessness deconditioning without structured assessment.
02
Using a negative routine CTPA to overrule an abnormal V/Q scan.
03
Starting PAH-targeted therapy before specialist haemodynamic classification.
04
Declaring disease inoperable outside a specialist CTEPH MDT.
05
Stopping anticoagulation because the clot appears chronic.
06
Giving repeated large fluid boluses to a congested failing right ventricle.
07
Assuming successful surgery ends the need for pulmonary-hypertension follow-up.