Pulmonary Hypertension (PH): Types, Causes, Symptoms, and Treatment
Pulmonary hypertension (PH) is a complex disease characterized by abnormally high blood pressure in the lungs. The World Health Organization (WHO) classification categorises PH into five groups based on the underlying cause and hemodynamic characteristics, aiding in accurate diagnosis and guiding treatment approaches.
Understanding the WHO Groups:
Group 1: Pulmonary Arterial Hypertension (PAH)
Most common type of PH but includes some rare subtypes of PH.
Cause: Narrowing and stiffening of small lung arteries, leading to high blood pressure in the pulmonary arteries.
Types: Idiopathic (unknown cause), familial (genetic), or associated with other conditions (connective tissue diseases, congenital heart defects [CHD]*, medications).
*CHD-PH is most common.
Symptoms: Shortness of breath, fatigue, chest pain, dizziness, fainting.
Diagnosis: Right heart catheterization (RHC) to measure blood pressure in the pulmonary arteries.
Treatment: No cure, but medications can improve symptoms and slow progression, lung transplantation in severe cases.
Group 2: Pulmonary Hypertension due to Left Heart Disease (PH-LHD)
A common type of PH in the elderly.
Cause: Problems with the left side of the heart, such as heart failure, valvular disease, or cardiomyopathy. Increased pressure in the left atrium backs up into the pulmonary arteries due to left ventricular dysfunction.
Symptoms: Like PAH, plus symptoms of heart disease (swelling, fatigue, difficulty breathing).
Diagnosis: Echocardiogram, RHC to assess heart function and pulmonary artery pressure.
Treatment: PH-LHD is usually treated by addressing the underlying heart condition with medications, surgery, or other interventions.
Group 3: Pulmonary Hypertension due to Lung Diseases and/or Hypoxia (PH-LD)
The second most common form of PH.
Cause: Chronic lung diseases like chronic obstructive pulmonary disease (COPD), interstitial lung disease (ILD), or obstructive sleep apnea (OSA) leading to low oxygen levels (hypoxia) and pulmonary vascular changes.
Symptoms: Similar to PAH and PH-LHD but may also include chronic cough, wheezing, and difficulty breathing.
Diagnosis: Lung function tests, blood tests, RHC.
Treatment: PH-LD is treated by addressing the underlying lung disease or hypoxia with medications, oxygen therapy, and lifestyle changes.
Group 4: Pulmonary Hypertension due to Pulmonary Thromboembolism (CTEPH)
A rare disease.
Types: Chronic (lasting longer than 3 months) or acute (sudden onset), with the chronic form (CTEPH) being more challenging to treat.
Cause: Unresolved blood clots (pulmonary emboli) obstructing pulmonary arteries, often following deep vein thrombosis (DVT).
Symptoms: Similar to PAH, but may also include sudden onset of shortness of breath, sharp chest pain, and coughing up blood.
Diagnosis: Imaging tests like CT scan, ventilation-perfusion scan, and RHC to assess blood clots and pulmonary artery pressure.
Treatment: Surgery (pulmonary endarterectomy), medications, or a combination of both.
Group 5: Pulmonary Hypertension with Unclear and/or Multifactorial Mechanisms (PH-M)
Relatively less common compared to other groups.
Cause: Combination of factors not fully understood or involves a combination of factors from different groups. May include high altitude exposure, sarcoidosis, hematologic (blood) disorders, and metabolic diseases.
Symptoms: Vary depending on the underlying cause.
Diagnosis: Extensive investigations to rule out other causes, RHC. Characterized by variable hemodynamics depending on the underlying cause.
Treatment: Based on individual patient’s symptoms and needs.
In conclusion, the WHO classification of PH is a fundamental tool used throughout the management of pulmonary hypertension. It aids in initial diagnosis, risk assessment, treatment planning, and contributes to standardized research efforts.
Additional Notes:
- The WHO classification is not a static system and may be revised as new knowledge emerges.
- This classification is for informational purposes only and should not be used for self-diagnosis or treatment.
Additional Reading: Updated Clinical Classification of Pulmonary Hypertension
If you suspect you have PH, consult a PH Specialist for proper evaluation and management.
Read about PH Medicines here.
