Pulmonary Hypertension

Related Subjects: |Assessing Breathlessness |Pulmonary Hypertension |Assessing Breathlessness |Pulmonary hypertension - Cor pulmonale

💨 Pulmonary Hypertension (PH) is a condition where the pulmonary circulation develops abnormally high pressures. Because the pulmonary circuit is normally a low-resistance, low-pressure system, sustained increases lead to 💔 right ventricular hypertrophy and ultimately right heart failure.

📖 About

• Defined as a mean pulmonary artery pressure >25 mmHg at rest, or >30 mmHg during exercise (via right heart catheterisation).
• Chronic pressure overload strains the RV, eventually leading to cor pulmonale.
• Can be primary (idiopathic) or, more commonly, secondary to other diseases.

⚙️ Physiology

• The pulmonary system is normally a low-resistance circuit, ~1/8th that of systemic vascular resistance.
• Shunts (ASD, VSD, PDA) initially push blood into the pulmonary circulation, but chronic overload eventually causes pulmonary vascular remodelling → pulmonary hypertension → reversal of flow (Eisenmenger’s syndrome).

🧬 Causes

• Primary (Idiopathic PAH) - Rare, typically in young adults (♀ > ♂, 2:1). - Median age of onset: 30–50 years. - Represents <1% of all PH cases.
• Secondary – much more common:
  • 💔 Left heart failure (most common overall cause).
  • 🌬️ Chronic lung disease: COPD, pulmonary fibrosis, interstitial lung disease.
  • 🩸 Chronic thromboembolic pulmonary hypertension (CTEPH).
  • 🔄 Left-to-right shunts (ASD, VSD, PDA → Eisenmenger’s).
  • 💊 Drugs: amphetamines, methamphetamines, L-tryptophan.
  • 🤒 Connective tissue diseases (e.g., scleroderma, SLE).
  • 🦠 HIV infection.

🩺 Clinical Features

• Progressive dyspnoea and fatigue.
• Right heart failure signs: raised JVP, hepatomegaly, peripheral oedema.
• Other: cyanosis, dizziness or syncope, chest pain/pressure, palpitations.

🔍 Investigations

• 🧪 Bloods: FBC, U&E, BNP (may be elevated).
• 📈 ECG: right axis deviation, RVH/strain, atrial arrhythmias (AF).
• 🩻 CXR: enlarged central pulmonary arteries, peripheral pruning.
• 🫀 Echo: RV dilation, TR jet velocity can estimate PAP.
• 💉 Right heart catheterisation: gold standard, directly measures pulmonary pressures.
• MRI: RV function and pulmonary artery anatomy.

📊 WHO Clinical Groups of Pulmonary Hypertension

• Group 1: Pulmonary arterial hypertension (PAH) – idiopathic, heritable, drug-induced, CTD-associated.
• Group 2: Due to left-sided heart disease.
• Group 3: Due to chronic lung disease/hypoxia (e.g., COPD, OSA).
• Group 4: Chronic thromboembolic PH (CTEPH).
• Group 5: Multifactorial/unclear (e.g., haematological disorders, systemic diseases).

💊 Management

• 🔹 General measures: low-salt diet, diuretics (furosemide), anticoagulation if indicated, vaccinate (influenza/pneumococcal).
• 🔹 Oxygen therapy: for chronic lung disease-related hypoxaemia.
• 🔹 Vasodilators: - Calcium channel blockers (nifedipine, amlodipine, diltiazem) – effective only in vasoreactive patients. - Prostacyclin analogues: IV epoprostenol, SC treprostinil. - Endothelin receptor antagonists: bosentan. - PDE-5 inhibitors: sildenafil, tadalafil.
• 🔹 Chronic thromboembolic PH: lifelong anticoagulation; pulmonary endarterectomy or balloon angioplasty can be curative.
• 🔹 Surgical options: lung or heart–lung transplantation in advanced refractory disease.

📌 Prognosis Pearl: - PH due to scleroderma has a poorer outlook (often progressive and refractory). - PH related to congenital heart disease (e.g., Eisenmenger’s) may have relatively better survival, as the RV adapts better over years of gradual pressure loading.