Pulmonary Hypertension for MRCP Respiratory: A Complete Clinical Guide

Pulmonary hypertension (PH) is one of those topics that reliably appears in MRCP Part 1, Part 2, and PACES — yet consistently catches candidates off guard. Whether it's a tricky best-of-five on classification, a data interpretation question on echo findings, or a Station 5 case with a loud P2 and raised JVP, PH demands a structured, confident approach. This guide breaks it down into the high-yield framework you need.

🫀 Why Pulmonary Hypertension Matters for MRCP

PH overlaps cardiology, respiratory, rheumatology, and hepatology, making it a favourite among examiners who love multi-system questions. The 2022 ESC/ERS guidelines refined the haemodynamic definitions, and candidates are expected to know these updates.

Key Update (2022 ESC/ERS): The definition of PH on right heart catheterisation (RHC) was lowered from ≥25 mmHg to ≥20 mmHg mean pulmonary artery pressure (mPAP). PAH (pre-capillary) requires PAWP ≤15 mmHg and PVR >2 WU.

This single change alone generates multiple exam questions.

📐 Classification: Know All Five Groups Cold

The WHO classification divides PH into five groups. Examiners frequently present a clinical vignette and ask you to identify the group — so you need to associate clinical scenarios with each.

🧠 High-Yield Group 1 Mnemonic

For PAH causes, remember the NAVAC framework:

• N — No known cause (Idiopathic PAH)

• A — Autoimmune (Systemic sclerosis, SLE, RA, MCTD)

• V — Vascular (congenital heart disease — Eisenmenger physiology)

• A — Associations (Portal hypertension, HIV, schistosomiasis)

• C — Chemical/drug-induced (anorexigens, methamphetamines)

Exam Pearl: In systemic sclerosis, PAH is the leading cause of death. Screen all SSc patients annually with echocardiography. A BNP/NT-proBNP can be used as a triage tool.

🩺 Clinical Presentation: The Station 5 Clues

In PACES, PH often presents as Station 3 (Cardiovascular) or Station 5 (Integrated). Here are the examination findings to actively look for:

General Examination

• Central cyanosis (especially in Eisenmenger or advanced disease)

• Clubbing — think congenital heart disease with right-to-left shunt, NOT idiopathic PAH (IPAH patients do not have clubbing)

• Ascites and peripheral oedema — decompensated right heart failure

Cardiovascular Examination

• Raised JVP with prominent 'a' wave (right atrial hypertrophy) or 'v' wave (tricuspid regurgitation)

• Right ventricular heave (parasternal)

• Palpable P2 (pulmonary component of the second heart sound)

• Loud P2 on auscultation — the hallmark of PH

• Pansystolic murmur (tricuspid regurgitation) — louder on inspiration

• Early diastolic murmur (Graham Steell) — pulmonary regurgitation due to dilated pulmonary valve ring

• Right-sided S4 (best heard at lower left sternal border)

Respiratory Examination

• May reveal signs of underlying lung disease (COPD, ILD) contributing to Group 3 PH

MRCP PACES Tip: If you hear a loud P2, RV heave, and raised JVP, immediately think pulmonary hypertension. Then work backwards to classify the group — check for chest wall deformity, surgical scars, kyphosis, oxygen-dependence, or systemic sclerosis features.

🔬 Investigations: The Diagnostic Pathway

Examiners love testing the diagnostic algorithm. Here's the structured approach:

First-Line

Echocardiographic Probability of PH (2015 ESC/ERS)

Definitive Diagnosis

Right heart catheterisation (RHC) is mandatory to:

1. Confirm PH (mPAP ≥20 mmHg)

2. Determine the group (pre-capillary vs post-capillary using PAWP)

3. Assess severity (PVR, cardiac index)

4. Perform vasoreactivity testing (in Group 1 only — using inhaled NO, IV epoprostenol, or adenosine)

Vasoreactivity Testing: A positive response is defined as a drop in mPAP ≥10 mmHg to ≤40 mmHg without a drop in cardiac output. Only ~15% of IPAH patients are vasoreactive — but these patients benefit from high-dose calcium channel blockers (nifedipine, diltiazem, amlodipine).

Additional Workup (to identify the underlying cause)

• Pulmonary function tests (obstructive/restrictive patterns)

• Arterial blood gas (hypoxia, hypercapnia)

• CT pulmonary angiogram (CTEPH, ILD patterns)

• V/Q scan (more sensitive than CTPA for CTEPH — do NOT use CTPA to exclude CTEPH)

• Ventilation/perfusion scintigraphy — mismatched perfusion defects suggest CTEPH

• Autoimmune screen (ANA, anti-centromere, anti-Scl70, anti-RNP, ANCA)

• HIV serology

• LFTs and portal pressure assessment

• Sleep study (overnight oximetry/polygraphy for OSA)

• 6-minute walk test (functional capacity and prognostic marker)

• BNP / NT-proBNP (prognostic marker)

💊 Management by Group

Group 1: PAH — The Most Testable

This is where MRCP focuses heavily on pharmacology. Treatment is risk-stratified (low/intermediate/high risk) using parameters like 6MWD, NT-proBNP, and WHO functional class.

Initial Therapy (treatment-naïve):

2022 ESC/ERS Guideline Update: Initial oral combination therapy (ERA + PDE-5 inhibitor) is now recommended for most treatment-naïve PAH patients at low or intermediate risk, rather than sequential monotherapy.

Important Contraindications & Side Effects:

• Bosentan → hepatotoxicity (monthly LFT monitoring required); drug interactions with warfarin and OCP

• Sildenafil → should NOT be combined with nitrates (severe hypotension); visual disturbance

• Riociguat → contraindicated with PDE-5 inhibitors; also treats inoperable/persistent CTEPH (Group 4)

• Epoprostenol → continuous IV infusion via tunnelled catheter; abrupt withdrawal causes rebound PH

CCB therapy (nifedipine/diltiazem) is reserved ONLY for vasoreactive IPAH/HPAH/DPAH patients.

Advanced therapy: Lung transplant (double lung or heart-lung) for refractory cases.

Group 2: Left Heart Disease

Treat the underlying cardiac condition. PAH-specific therapy is not routinely recommended and may worsen outcomes.

• Diuretics for volume overload

• Optimise heart failure therapy

• Valve repair/replacement for valvular disease

Group 3: Lung Disease & Hypoxia

• Long-term oxygen therapy (LTOT) to maintain PaO₂ >8 kPa

• Treat the underlying lung disease (COPD, ILD, OSA with CPAP)

• PAH-specific therapy is not routinely recommended but may be considered in selected patients where PH is disproportionate to lung disease severity

Group 4: CTEPH

• Pulmonary endarterectomy (PEA) — potentially curative, first-line for operable disease

• Riociguat — for inoperable disease or persistent PH post-PEA

• Balloon pulmonary angioplasty (BPA) — emerging option for non-operable proximal disease

• Lifelong anticoagulation

Exam Classic: A patient with previous DVT/PE presents with progressive breathlessness, echo shows raised RVSP, and V/Q scan shows multiple mismatched segmental perfusion defects. This is CTEPH — request V/Q scan, NOT repeat CTPA. Management is surgical PEA if operable.

Group 5: Multifactorial

Manage the underlying condition. PAH-specific therapy may be considered on a case-by-case basis.

🚨 Referral & Follow-Up

All patients with confirmed PH should be referred to a specialist PH centre for:

• Definitive RHC and vasoreactivity testing

• Multidisciplinary treatment planning

• Ongoing risk assessment

⭐ MRCP High-Yield Exam Pearls

1. Definition changed (2022): mPAP ≥20 mmHg (was ≥25 mmHg). Pre-capillary PH: PAWP ≤15, PVR >2 WU.

2. Loud P2 + RV heave + raised JVP = pulmonary hypertension on PACES.

3. Clubbing + cyanosis + PH → think Eisenmenger syndrome (not IPAH).

4. Systemic sclerosis + breathlessness → screen for PAH with echo and BNP. PAH is the leading cause of death in SSc.

5. V/Q scan is the investigation of choice for CTEPH, not CTPA.

6. Vasoreactive IPAH patients get high-dose CCBs first-line. All others get PAH-specific therapy.

7. Riociguat treats BOTH PAH (Group 1) AND inoperable/persistent CTEPH (Group 4).

8. Sildenafil + nitrates = contraindicated (profound hypotension).

9. Bosentan → hepatotoxicity → monthly LFT monitoring.

10. Portopulmonary HTN is Group 1 (PAH), while hepatopulmonary syndrome is NOT (it's hypoxia from intrapulmonary vasodilation).

📚 Summary Table for Rapid Revision

🎯 Final Thoughts

Pulmonary hypertension is a high-yield MRCP topic that rewards candidates who understand the classification system and diagnostic pathway. The key is not memorising every drug dose — it's knowing which group the patient belongs to, because that determines everything downstream.

For PACES, practice presenting the cardiovascular examination finding fluently — examiners want to hear you say "loud pulmonary component to the second heart sound, right ventricular heave, and raised JVP" with confidence. Then follow with a structured differential and investigation plan that shows you understand the five-group classification.

For written exams, focus on the 2022 haemodynamic definitions, the vasoreactivity testing criteria, and the V/Q scan as first-line for CTEPH. These are the questions that separate passes from distinctions.

Good luck with your revision — and remember, in PH management, group matters more than pressure.

Disclaimer: This blog is for educational purposes and exam preparation. Always refer to current local guidelines and specialist centre protocols for clinical decision-making.