Pulmonary Hypertension: The Silent Killer Nobody Warns You About
Pulmonary hypertension is a serious, progressive disease of the lung blood vessels that is frequently mistaken for asthma, deconditioning, or heart disease. A pulmonologist explains what it is, why it is so often diagnosed late, and what modern treatment can do when it is caught in time.
There is a condition that causes breathlessness, fatigue, and chest tightness — symptoms so common that they are attributed to dozens of other causes before anyone thinks to look at the blood vessels of the lungs. Patients are told they have asthma. They are told they are deconditioned. They are told their heart is fine and they should exercise more. Meanwhile, the pressure in their pulmonary arteries is rising, their right heart is straining against an impossible workload, and the window for effective treatment is narrowing with every month that passes without a correct diagnosis.
Pulmonary hypertension — elevated blood pressure in the arteries supplying the lungs — is one of the most underdiagnosed serious conditions in medicine. The average time from symptom onset to correct diagnosis is two to three years globally. In Pakistan, where awareness is low and diagnostic resources are less consistently available, the delay is frequently longer. By the time many patients receive the diagnosis, significant irreversible vascular remodelling has already occurred.
I want to change that for the patients who read this article. Understanding pulmonary hypertension — its symptoms, its causes, how it is diagnosed, and what treatment exists — can be the difference between catching it early and catching it too late.
What Is Pulmonary Hypertension?
To understand pulmonary hypertension, it helps to first understand the normal circulation of blood through the lungs. The right side of the heart — the right ventricle — pumps deoxygenated blood through the pulmonary arteries into the lungs, where it picks up oxygen and releases carbon dioxide. This is a low-pressure system. The pulmonary arteries are designed to handle blood at relatively low pressures — normally a mean pulmonary artery pressure below 20 mmHg — because the right ventricle is a thin-walled, low-pressure chamber not designed for sustained high-resistance work.
Pulmonary hypertension is defined as a mean pulmonary artery pressure above 20 mmHg at rest, measured during right heart catheterisation. When the pressure in the pulmonary arteries rises, the right ventricle must work progressively harder. Over time it enlarges, its walls thicken, its function deteriorates, and eventually right heart failure develops — the final, often rapidly fatal, consequence of untreated pulmonary hypertension.
It is critically important to understand that pulmonary hypertension is entirely distinct from systemic hypertension — the common high blood pressure that affects the left-sided circulation. The two conditions share a name but differ completely in their mechanisms, causes, consequences, and treatments. A normal blood pressure reading at the arm tells you nothing about pulmonary artery pressure.
The Five Groups of Pulmonary Hypertension
The WHO classifies pulmonary hypertension into five groups based on the underlying mechanism. This classification is not merely academic — it directly determines treatment, and treating the wrong group with the wrong therapy can cause significant harm.
Group 1 — Pulmonary Arterial Hypertension (PAH)
PAH is caused by intrinsic disease of the small pulmonary arteries — progressive obliteration of the vessel lumen through smooth muscle proliferation, inflammation, and fibrosis. It is the rarest but most severe form and the one most commonly treated with the specific vasodilator therapies developed over the past two decades. PAH can be idiopathic, heritable, or associated with connective tissue disease — particularly systemic sclerosis — congenital heart disease, HIV infection, and portal hypertension. Women of reproductive age are disproportionately affected.
Group 2 — Due to Left Heart Disease
The most common form overall. When the left heart fails, pressure backs up through the pulmonary veins into the pulmonary arteries. Treatment focuses on optimising the underlying left heart disease rather than using PAH-specific vasodilators, which can be harmful in this group.
Group 3 — Due to Lung Disease and Hypoxia
Chronic low blood oxygen from COPD, pulmonary fibrosis, sleep apnea, and other lung conditions causes pulmonary vasoconstriction and progressive vascular remodelling. Particularly important in Pakistan, where COPD, TB-related lung damage, and untreated sleep apnea are all common. Long-term oxygen therapy is the primary intervention for hypoxic patients.
Group 4 — Chronic Thromboembolic PH (CTEPH)
CTEPH develops when pulmonary emboli fail to dissolve after an acute PE event, organising into chronic obstructions that progressively elevate pulmonary pressure. It is the only potentially curable form — surgical pulmonary endarterectomy can normalise pressures in appropriately selected patients. It develops in approximately 3 to 5 percent of PE survivors and should be investigated in any patient with persistent breathlessness after a PE episode.
Group 5 — Unclear Mechanisms
PH associated with haematological disorders, sarcoidosis, thyroid disease, and other multifactorial conditions. Management focuses on the underlying condition alongside pulmonary vascular specialist input.
Recognising the Symptoms — Why Diagnosis Is So Often Delayed
The symptoms of pulmonary hypertension develop slowly, mimic many other conditions, and are easy to normalise. This is the primary reason for the two-to-three-year diagnostic delay that characterises this condition globally.
The earliest and most consistent symptom. Initially only on significant exertion, it gradually occurs with less and less activity. Patients stop climbing stairs, reduce walking distances, and curtail activities — each adaptation making the breathlessness less obvious while the disease progresses silently.
A profound, disproportionate fatigue reflecting reduced cardiac output as the struggling right ventricle fails to maintain adequate blood flow. Patients describe exhaustion after minimal activity and inability to sustain tasks they previously managed easily.
Exertional dizziness or syncope — particularly during or after physical activity — indicates the right ventricle cannot increase cardiac output sufficiently, causing a transient drop in brain perfusion. Syncope in PH is a marker of advanced disease and poor prognosis.
Right ventricular chest pain — caused by right heart ischaemia as the overloaded ventricle outstrips its blood supply — produces exertional chest tightness closely mimicking angina, frequently leading to extensive left-sided cardiac investigation before the correct pulmonary vascular diagnosis is considered.
Peripheral oedema develops as right heart failure progresses. The failing right ventricle cannot maintain forward flow, causing venous congestion and fluid accumulation in the tissues. Often initially attributed to kidney disease, venous insufficiency, or medication side effects.
In advanced PH — particularly when associated with a right-to-left shunt — cyanosis develops as deoxygenated blood bypasses the lungs and enters the systemic circulation. It is a marker of severe advanced disease indicating critically reduced oxygen delivery.
The patient I remember most vividly was a thirty-two-year-old woman who had been told she was deconditioned and needed to exercise more. She had been breathless for two years. By the time she reached my clinic, her right ventricle was severely dilated and her mean pulmonary artery pressure was 58 mmHg. Two years of being told to push through had cost her two years of treatment. Pulmonary hypertension does not wait. And neither should the diagnosis.
— Dr. Nabila Zaheer, Pulmonologist
Who Is Most at Risk?
Key Risk Groups for Pulmonary Hypertension in Pakistan
- Women of reproductive age — PAH disproportionately affects women between 20 and 50, with a female-to-male ratio of approximately 3:1. Young women with unexplained progressive breathlessness must have pulmonary hypertension specifically excluded.
- Patients with connective tissue disease — systemic sclerosis carries the highest PAH risk — up to 12 percent of scleroderma patients develop PAH. Annual echocardiographic screening is recommended for all scleroderma patients.
- Patients with COPD or pulmonary fibrosis — chronic hypoxia from these conditions is the most common pathway to Group 3 PH in Pakistan. Patients whose breathlessness seems disproportionate to their lung function impairment should be screened for PH.
- Pulmonary embolism survivors — approximately 3 to 5 percent develop CTEPH. Any patient with persistent breathlessness three to six months after a PE should be evaluated — surgical treatment is curative in eligible patients.
- Patients with congenital heart disease — uncorrected left-to-right shunts cause pulmonary vascular disease through chronic volume overload. In Pakistan, where many congenital defects go uncorrected into adulthood, this is an important underappreciated cause.
- Patients with HIV — HIV-associated PAH occurs in approximately 0.5 percent of people living with HIV and may develop at any CD4 count, requiring specialist management.
- Patients with severe untreated sleep apnea — repetitive nocturnal hypoxia promotes pulmonary vasoconstriction and can contribute to PH development, particularly in patients with multiple risk factors.
How Pulmonary Hypertension Is Diagnosed
Diagnosing PH requires a structured, stepwise approach beginning with non-invasive investigations and culminating in right heart catheterisation. The diagnosis should always be made in a specialist centre with expertise in pulmonary vascular disease.
Echocardiogram — The Essential Screening Tool
A transthoracic echocardiogram estimates pulmonary artery systolic pressure, assesses right ventricular size and function, identifies left heart disease as a potential cause, and detects structural cardiac abnormalities. It cannot definitively diagnose PH — it provides an estimate, not a measurement — but it is the essential first step that directs further investigation. An echocardiogram suggesting elevated pulmonary pressures should always prompt specialist referral, not watchful waiting.
Pulmonary Function Tests and DLCO
Spirometry and full pulmonary function testing identify underlying lung disease as a Group 3 cause. A characteristically reduced DLCO — disproportionate to spirometric impairment — is a recognised feature of PAH and CTEPH, reflecting vascular obliteration reducing gas exchange surface area. An isolated, disproportionate DLCO reduction in a patient with otherwise normal lung function should always prompt echocardiographic assessment.
CT and V/Q Scanning
CTPA identifies pulmonary vascular abnormalities and may reveal the chronic organised clot burden of CTEPH. A ventilation-perfusion (V/Q) scan is the preferred investigation for CTEPH screening, more sensitive than CTPA for detecting the patchy peripheral perfusion defects characteristic of chronic thromboembolic disease.
Right Heart Catheterisation — The Gold Standard
Right heart catheterisation is the definitive diagnostic procedure. A thin catheter is passed through a vein into the right heart and pulmonary arteries under X-ray guidance, directly measuring pulmonary artery pressure, pulmonary vascular resistance, cardiac output, and wedge pressure. It also allows acute vasodilator testing to identify vasoreactive PAH patients who benefit from calcium channel blocker therapy. Right heart catheterisation is safe in experienced hands and is essential before committing a patient to long-term PAH-specific therapy.
Treatment: How Pulmonary Hypertension Is Managed Today
PH management has been transformed over the past two decades. Where previously the condition carried an almost uniformly grim prognosis, patients diagnosed today — particularly those with Group 1 PAH — have access to multiple effective treatments that substantially extend survival and improve quality of life.
For Groups 2, 3, and 5, primary treatment is optimal management of the underlying condition. For Group 2, this means optimising left heart failure. For Group 3, this means maximising lung disease treatment and providing long-term oxygen therapy for hypoxic patients — oxygen for at least 15 hours daily reduces hypoxic vasoconstriction and improves survival. For CTEPH, surgical pulmonary endarterectomy in operable patients is potentially curative.
Three pharmacological pathways are targeted by PAH-specific drugs. Phosphodiesterase-5 inhibitors (sildenafil, tadalafil) promote vasodilation through the nitric oxide pathway. Endothelin receptor antagonists (bosentan, ambrisentan, macitentan) block the potent vasoconstrictor endothelin-1. Prostacyclin analogues (epoprostenol, treprostinil, iloprost) replace deficient prostacyclin that normally promotes vasodilation. Modern guidelines recommend combination therapy — typically two agents from different pathways simultaneously — as superior to sequential monotherapy for most PAH patients.
Approximately 10 percent of PAH patients demonstrate significant vasodilator response during right heart catheterisation. These "vasoreactive" patients benefit from high-dose calcium channel blockers and have significantly better long-term outcomes. Vasoreactivity testing is mandatory before treatment — calcium channel blockers must never be prescribed empirically for PAH without demonstrated vasoreactivity, as they can cause serious harm in non-responders.
Removal of organised thromboembolic material from the pulmonary arteries is potentially curative for operable CTEPH, normalising pulmonary pressures in appropriately selected patients. For inoperable CTEPH, balloon pulmonary angioplasty and the oral drug riociguat offer meaningful haemodynamic and functional improvement.
Diuretics manage right heart failure fluid retention. Anticoagulation is indicated in CTEPH and selected PAH patients. Iron deficiency — common in PAH and independently associated with worse outcomes — should be corrected. Supervised exercise rehabilitation improves functional capacity in stable PAH patients as an adjunct to medical therapy. Pregnancy is contraindicated in PAH due to high maternal mortality — contraceptive counselling is essential for all women of reproductive age with PH.
Bilateral lung or heart-lung transplantation remains an option for younger patients with PAH who deteriorate despite maximal medical therapy and have no significant comorbidities. It carries significant operative risk and long-term immunosuppression complications but provides substantially extended survival for carefully selected patients at experienced centres.
Frequently Asked Questions
Is pulmonary hypertension the same as regular high blood pressure?
No — they are completely different conditions. Regular high blood pressure (systemic hypertension) affects the arteries throughout the body and is measured with a blood pressure cuff at the arm. Pulmonary hypertension affects only the blood vessels of the lungs and the right side of the heart, and cannot be detected with a standard blood pressure measurement. A normal blood pressure reading tells you nothing about pulmonary artery pressure. The two conditions have different causes, different symptoms, different treatments, and different prognoses — they are related only by the word "hypertension."
Can pulmonary hypertension be cured?
It depends on the type. CTEPH — caused by unresolved blood clots — is potentially curable through surgical pulmonary endarterectomy, which can normalise pulmonary pressures completely in eligible patients. Group 2 and Group 3 PH often improve significantly when the underlying left heart or lung disease is effectively treated. Idiopathic PAH is not currently curable but is increasingly manageable with modern targeted therapies that substantially extend survival and improve quality of life. Research into treatments targeting the fundamental mechanisms of vascular remodelling continues actively.
My echocardiogram showed possible pulmonary hypertension. What should I do next?
An echocardiogram suggesting elevated pulmonary artery pressure is an important finding requiring further investigation — not reassurance and monitoring. The next step is referral to a pulmonary hypertension specialist for a comprehensive assessment including pulmonary function tests, CT imaging, blood tests for underlying causes, and in most cases right heart catheterisation to confirm the diagnosis and measure pressures directly. Do not accept echocardiographic "possible PH" as a final answer without specialist evaluation. Early referral is critical because earlier treatment produces substantially better outcomes.
I had a pulmonary embolism six months ago and I am still breathless. Could I have CTEPH?
Yes — this is exactly the clinical scenario that should prompt CTEPH investigation. If you have persistent breathlessness three to six months after a PE — even if your anticoagulation was appropriate and completed — you should be evaluated for CTEPH with a ventilation-perfusion scan and echocardiogram. CTEPH is the only potentially curable form of pulmonary hypertension, and surgical treatment is most successful before significant secondary vascular disease develops. Do not assume persistent breathlessness after PE is simply deconditioning — it deserves specific investigation.
Can untreated sleep apnea cause pulmonary hypertension?
Yes — though the PH associated with sleep apnea is usually mild. Severe untreated OSA causes repetitive nocturnal hypoxia that triggers pulmonary vasoconstriction and, over years, promotes structural vascular changes. CPAP therapy — which eliminates apnea events and prevents hypoxia — typically improves or normalises sleep-apnea-related PH when started before significant fixed vascular remodelling has occurred. This is another important reason to diagnose and treat sleep apnea promptly, beyond simply improving sleep quality.
Breathlessness That Cannot Be Explained Deserves a Specialist's Attention.
If you have progressive breathlessness, unexplained fatigue, or exertional chest tightness that has not been adequately explained — or if you have been told your heart and lungs are fine but you know something is wrong — a dedicated pulmonary vascular assessment may provide the answers. Book a consultation with Dr. Nabila Zaheer at PulmoCare today.
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