What is the range of pulmonary hypertension by pulmonary artery pressure (PAP)?

Pulmonary Hypertension Classification by Pulmonary Artery Pressure

Pulmonary hypertension is defined as a mean pulmonary arterial pressure (mPAP) ≥25 mmHg at rest as assessed by right heart catheterization, with normal pulmonary hypertension having an upper limit of approximately 20 mmHg. 1, 2

Diagnostic Pressure Ranges

Mean Pulmonary Arterial Pressure (mPAP)

• Normal range: 14 ± 3 mmHg 1, 2
• Upper limit of normal: ~20 mmHg 1, 2
• Borderline/uncertain significance: 21-24 mmHg (requires monitoring in at-risk patients) 1, 2
• Definite pulmonary hypertension: ≥25 mmHg 1, 2

Pulmonary Artery Systolic Pressure (PASP)

• Normal range: 15-30 mmHg 2
• Elevated/concerning: >30 mmHg (associated with increased mortality) 1
• High probability of PH: >36 mmHg (corresponds to tricuspid regurgitation velocity >2.8 m/s) 1

Hemodynamic Classification

1. Pre-capillary PH 1

   • mPAP ≥25 mmHg
   • PAWP (Pulmonary Artery Wedge Pressure) ≤15 mmHg
   • PVR (Pulmonary Vascular Resistance) >3 Wood Units

2. Post-capillary PH 1

   • mPAP ≥25 mmHg
   • PAWP >15 mmHg

   Subtypes:

   • Isolated post-capillary PH: DPG (Diastolic Pressure Gradient) <7 mmHg and/or PVR ≤3 WU
   • Combined post- and pre-capillary PH: DPG ≥7 mmHg and/or PVR >3 WU

Prognostic Implications

• Mortality increases significantly with elevated pulmonary pressures:
  • mPAP 19-24 mmHg: ~25% 5-year mortality 1
  • mPAP ≥25 mmHg: ~40% 5-year mortality 1
  • PASP 30-32 mmHg: 28.9% 5-year mortality (66% higher than those with PASP 28-30 mmHg) 1

Clinical Classification Groups

Pulmonary hypertension is classified into five main groups based on etiology 1, 3:

1. Group 1: Pulmonary Arterial Hypertension (PAH)

   • Idiopathic, heritable, drug-induced, or associated with other conditions

2. Group 2: PH due to Left Heart Disease

   • Systolic dysfunction, diastolic dysfunction, valvular disease

3. Group 3: PH due to Lung Diseases and/or Hypoxemia

   • COPD, interstitial lung disease, sleep disorders

4. Group 4: Chronic Thromboembolic PH

   • Obstruction of pulmonary arteries

5. Group 5: PH with Unclear and/or Multifactorial Mechanisms

   • Hematological, systemic, metabolic disorders

Important Clinical Considerations

• Right heart catheterization remains the gold standard for diagnosis 2
• Echocardiography provides estimates but has limitations compared to direct measurement 2
• Values of mPAP between 21-24 mmHg warrant close follow-up in at-risk patients 2
• Even mildly elevated PASP (>30 mmHg) is associated with significantly increased mortality 1
• The term "out of proportion PH" has been abandoned for PH associated with left heart disease or lung disease 1

Diagnostic Approach

• Patients with high clinical suspicion and echocardiographic evidence of elevated pulmonary pressures should be referred to specialized PH centers for definitive diagnosis 1, 2
• The presence of right ventricular dysfunction significantly worsens prognosis and requires urgent evaluation 4

Understanding these pressure ranges and classifications is essential for proper diagnosis, risk stratification, and management of patients with pulmonary hypertension.