Pulmonary hypertension (PH) is a condition characterized by elevated pulmonary arterial pressure, leading to progressive right heart failure if untreated. According to the latest guidelines from the European Society of Cardiology (ESC) and European Respiratory Society (ERS), PH is defined as a mean pulmonary arterial pressure (mPAP) ≥ 20 mm Hg at rest, measured via right heart catheterization.
Classification of Pulmonary Hypertension
| Group | Cause | Examples |
|---|---|---|
| Group 1: Pulmonary Arterial Hypertension (PAH) | Idiopathic, heritable, or drug-induced, associated with conditions such as connective tissue disease, HIV, or congenital heart disease | Idiopathic PAH, PAH in systemic sclerosis |
| Group 2: PH due to Left Heart Disease | Increased pressure in the left atrium or left ventricle due to systolic or diastolic dysfunction, valvular disease | Heart failure, mitral stenosis |
| Group 3: PH due to Lung Disease/Hypoxia | Chronic obstructive pulmonary disease (COPD), interstitial lung disease, sleep-disordered breathing | COPD, obstructive sleep apnea |
| Group 4: Chronic Thromboembolic Pulmonary Hypertension (CTEPH) | Chronic thromboembolic disease causing obstruction of the pulmonary arteries | Chronic pulmonary embolism |
| Group 5: PH with Unclear/Multifactorial Mechanisms | Includes multiple causes, often complex | Sarcoidosis, chronic hemolytic anemia |
Pathophysiology
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Vascular Remodeling: In PAH, vasoconstriction and abnormal remodeling of the pulmonary arteries lead to increased resistance. This is caused by endothelial dysfunction, smooth muscle hypertrophy, and fibrosis of the vessel walls.
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Right Ventricular Overload: As pulmonary arterial pressures rise, the right ventricle must work harder to pump blood through the lungs. Over time, this leads to right ventricular hypertrophy, dilation, and eventually right heart failure.
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Hypoxic Vasoconstriction: In cases of PH due to chronic lung disease (Group 3), prolonged low oxygen levels (hypoxia) induce vasoconstriction of the pulmonary arteries, contributing to elevated pressures.
Clinical Features
Patients with PH often present with non-specific symptoms, which can lead to delayed diagnosis. Symptoms may vary depending on the underlying cause but typically include:
| Symptom | Description |
|---|---|
| Dyspnea | Most common presenting symptom, worsened by exertion. |
| Fatigue | Resulting from decreased cardiac output and oxygen delivery. |
| Chest Pain | Often due to right ventricular ischemia or pulmonary artery dilation. |
| Syncope | Occurs in advanced cases, especially during exertion. |
| Peripheral Edema | Indicative of right heart failure and fluid retention. |
| Palpitations | May occur due to arrhythmias like atrial fibrillation. |
| Cyanosis | Seen in severe cases with right-to-left shunting through a patent foramen ovale. |
On physical examination, the following signs may be observed:
- Loud P2 (pulmonic component of the second heart sound)
- Right ventricular heave
- Jugular venous distension
- Hepatomegaly
- Ascites and peripheral edema in advanced cases
Diagnosis
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Echocardiography:
- Initial screening tool.
- Provides estimates of pulmonary arterial pressures, right ventricular size, and function.
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Right Heart Catheterization:
- Gold standard for diagnosis.
- Confirms elevated mPAP ≥ 20 mm Hg and pulmonary vascular resistance (PVR).
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Electrocardiogram (ECG):
- Shows right atrial enlargement, right ventricular hypertrophy, and right axis deviation.
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Chest X-ray:
- May reveal prominent pulmonary arteries or right ventricular enlargement.
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CT Pulmonary Angiography:
- Useful in diagnosing chronic thromboembolic disease (CTEPH).
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Pulmonary Function Tests:
- Performed to assess for underlying lung diseases such as COPD or interstitial lung disease.
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Ventilation-Perfusion (V/Q) Scan:
- Used in the evaluation of CTEPH to detect perfusion defects.
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Biomarkers:
- Elevated B-type natriuretic peptide (BNP) or NT-proBNP suggests right heart strain.
Management
Management of PH depends on the underlying cause and group classification. A multidisciplinary approach involving cardiologists, pulmonologists, and other specialists is recommended. The following table summarizes treatment strategies by group:
| Group | Management |
|---|---|
| Group 1 (PAH) | – Endothelin receptor antagonists (e.g., bosentan, ambrisentan) |
| – Phosphodiesterase-5 inhibitors (e.g., sildenafil, tadalafil) | |
| – Prostacyclin analogs (e.g., epoprostenol, treprostinil) | |
| – Soluble guanylate cyclase stimulators (e.g., riociguat) | |
| – Lung transplantation in refractory cases. | |
| Group 2 (Left Heart Disease) | – Treat underlying heart failure with diuretics, ACE inhibitors, beta blockers, and aldosterone antagonists. |
| Group 3 (Lung Disease) | – Oxygen therapy for chronic hypoxemia. |
| – Manage underlying lung diseases (e.g., COPD, interstitial lung disease). | |
| Group 4 (CTEPH) | – Anticoagulation therapy for life. |
| – Pulmonary thromboendarterectomy for operable cases. | |
| – Balloon pulmonary angioplasty for inoperable patients. | |
| Group 5 (Unclear Mechanisms) | – Individualized treatment based on etiology. |
General Measures:
- Anticoagulation: Used in Group 4 (CTEPH) and selected Group 1 (PAH) patients.
- Diuretics: To manage fluid retention and right heart failure symptoms.
- Oxygen Therapy: For patients with chronic hypoxia, particularly in Group 3 PH.
Advanced Therapies:
- Prostanoids: Continuous intravenous epoprostenol is recommended for patients with severe PAH.
- Endothelin Receptor Antagonists (ERAs): These drugs, like bosentan, help to reduce pulmonary vascular resistance by blocking endothelin, a potent vasoconstrictor.
- Phosphodiesterase-5 Inhibitors (PDE5): Drugs like sildenafil and tadalafil enhance the effect of nitric oxide, leading to vasodilation of pulmonary arteries.
- Soluble Guanylate Cyclase Stimulators: Riociguat can be used for both PAH and inoperable CTEPH to improve exercise capacity and delay clinical worsening.
Prognosis
The prognosis of pulmonary hypertension varies according to the underlying cause and response to treatment. Early detection and appropriate management can improve outcomes, especially in PAH and CTEPH. Right heart function is a key determinant of prognosis, with worsening right ventricular failure associated with poor outcomes. In advanced stages, lung transplantation may be the only option.
About the Author
Dr. Akif Ahamad Baig is a distinguished Consultant Interventional Cardiologist currently based at Aster Ramesh Hospital in Guntur. He completed his DM in Cardiology from Guntur Medical College in December 2023. Dr. Baig also holds a DNB in General Medicine from P.D. Hinduja National Hospital, Mumbai, and earned his MBBS from Siddhartha Medical College, Vijayawada, in 2016.