Causes
Secondary PH develops due to various underlying conditions that affect the pulmonary arteries or the left side of the heart. These conditions can be broadly categorized as:- Left heart disease: Conditions such as mitral valve disease, aortic valve disease, heart failure with preserved ejection fraction (HFpEF), and heart failure with reduced ejection fraction (HFrEF) can increase pressure in the left atrium, which then backs up into the pulmonary circulation.
- Lung diseases: Chronic lung conditions that cause low oxygen levels (hypoxia) or damage the lung tissue can lead to pulmonary vasoconstriction (narrowing of the blood vessels) and increased pulmonary artery pressure. Examples include:
- Chronic obstructive pulmonary disease (COPD)
- Interstitial lung diseases (e.g., pulmonary fibrosis)
- Sleep-disordered breathing (e.g., obstructive sleep apnea)
- Chronic blood clots in the lungs: Pulmonary embolism, especially when recurrent or unresolved, can lead to chronic thromboembolic pulmonary hypertension (CTEPH).
- Connective tissue diseases: Autoimmune diseases like scleroderma, lupus, and rheumatoid arthritis can affect the blood vessels in the lungs.
- Other conditions:
- Sickle cell anemia
- Liver disease (cirrhosis)
- HIV infection
- Congenital heart defects
Symptoms
The symptoms of secondary PH are often similar to those of primary PH, but they may be overshadowed or attributed to the underlying condition. Symptoms may include:- Shortness of breath (dyspnea), initially during exertion and later at rest
- Fatigue
- Chest pain
- Dizziness or lightheadedness
- Swelling in the ankles, legs, or abdomen (edema)
- Rapid heartbeat (tachycardia)
- Cough
- Bluish discoloration of the lips or skin (cyanosis)
Diagnosis
Diagnosing secondary PH involves identifying both the pulmonary hypertension and the underlying cause. Diagnostic procedures include:- Medical history and physical examination: To assess symptoms, risk factors, and potential underlying conditions.
- Echocardiogram: An ultrasound of the heart to estimate pulmonary artery pressure and assess heart function.
- Pulmonary function tests (PFTs): To evaluate lung function and identify underlying lung diseases.
- Chest X-ray: To visualize the lungs and heart.
- CT scan: To provide detailed images of the lungs and pulmonary arteries, which is particularly important in diagnosing CTEPH.
- Right heart catheterization: The gold standard for diagnosing PH. It directly measures the pressures in the heart and pulmonary arteries and assesses how well the heart is pumping.
- Blood tests: To check for underlying conditions (e.g., connective tissue diseases, liver disease, HIV) and assess overall health.
- Ventilation-perfusion (V/Q) scan: To evaluate blood flow and airflow in the lungs, primarily used to diagnose CTEPH.
Treatment
The primary goal of treatment for secondary PH is to manage the underlying condition and alleviate the symptoms of pulmonary hypertension. Treatment strategies may include:- Treating the underlying condition: Addressing the root cause is crucial. For example:
- Medications or surgery for left heart disease
- Oxygen therapy, bronchodilators, or pulmonary rehabilitation for lung diseases
- Anticoagulation and pulmonary thromboendarterectomy (PTE) surgery for CTEPH
- Immunosuppressive therapy for connective tissue diseases
- Pulmonary hypertension-specific medications: These medications can help to dilate the pulmonary arteries, reduce pulmonary artery pressure, and improve symptoms:
- Phosphodiesterase-5 (PDE-5) inhibitors (e.g., sildenafil, tadalafil)
- Endothelin receptor antagonists (ERAs) (e.g., bosentan, ambrisentan)
- Prostanoids (e.g., epoprostenol, treprostinil)
- Soluble guanylate cyclase (sGC) stimulators (e.g., riociguat)
- Oxygen therapy: To maintain adequate oxygen levels, especially in patients with PH secondary to lung disease.
- Diuretics: To reduce fluid buildup and swelling.
- Lung transplantation: May be an option in severe cases that do not respond to other treatments.
Living With Secondary Pulmonary Hypertension
Because secondary pulmonary hypertension is a consequence rather than a disease of its own, the treatment that helps most is rarely a pulmonary hypertension drug. Knowing which group you fall into, what actually lowers the pressure, and which medications can do harm is the practical heart of managing it.
Why the pulmonary hypertension drugs are usually not the answer
Medications such as sildenafil and tadalafil were developed for pulmonary arterial hypertension, the rarer form in which the lung arteries themselves are diseased. In pressure that rises from left heart disease or from lung disease, trials have not shown benefit, and in some people they worsen oxygen levels or fluid buildup. The exception is chronic clot disease, where surgery to clear the arteries can be curative and a specific medication is used when surgery is not possible. A right heart catheterization is what sorts the groups, which is why it is done before any pulmonary hypertension drug is considered.
Treating the cause is treating the pressure
When congestive heart failure or valvular heart disease is the driver, the pulmonary pressure follows the left-sided pressure, so diuretics such as furosemide, blood pressure control, and valve repair when indicated are the treatment. When COPD or lung scarring is the cause, correcting low oxygen with supplemental oxygen, used for the prescribed hours including sleep, does more for the pressure than any tablet. Untreated obstructive sleep apnea is a common and reversible contributor, and CPAP lowers pulmonary pressure measurably.
Fluid, salt, and the daily weight
The right side of the heart tolerates fluid overload poorly. A daily morning weight with a rule for calling when it climbs by a few pounds in a few days, a sodium limit, and adjusting the diuretic to that weight prevents most admissions. Florida heat complicates this: sweating concentrates the blood and can tip a diuretic dose into dehydration and dizziness, so fluid targets are set individually rather than by a general rule. Our heart failure early signs article covers the warning pattern.
Exercise, altitude, and pregnancy
Supervised pulmonary or cardiac rehabilitation improves stamina and is safe when the condition is stable; unsupervised heavy exertion, straining, and saunas are avoided because they drop the blood pressure the right heart depends on. Air travel is usually possible with oxygen arranged in advance if it is needed at sea level. Pregnancy carries serious risk and is planned with specialists, and reliable contraception is part of the conversation. The pulmonary embolism page explains the clot disease that accounts for the surgically curable form.
Signs that mean the right heart is struggling
Fainting or near-fainting with exertion, a new or rapidly rising swelling of the legs or abdomen, chest pain, and breathlessness at rest signal right heart strain and need urgent evaluation. Our pulmonary team coordinates the workup between cardiology and pulmonology and follows the underlying condition. The NHLBI and MedlinePlus publish patient guidance on the types and their treatment.
If you have been told your echocardiogram shows high lung pressure and the cause has not been sorted out, schedule a visit.