What are normal pulmonary artery systolic and diastolic pressures and how do they compare to pressures in pulmonary hypertension?

Normal and Abnormal Pulmonary Artery Pressures

Normal pulmonary artery pressure is defined as a mean pulmonary arterial pressure (mPAP) of 14 ± 3 mmHg at rest, with an upper limit of normal of approximately 20 mmHg, while pulmonary hypertension is defined as a mPAP ≥25 mmHg at rest as assessed by right heart catheterization. 1, 2

Normal Pulmonary Artery Pressures

• Mean pulmonary arterial pressure (mPAP): 14 ± 3 mmHg (normal range)
• Upper limit of normal mPAP: 20 mmHg
• Clinical significance of mPAP between 21-24 mmHg: Unclear, but warrants close follow-up in patients at risk for developing pulmonary arterial hypertension 1

Pulmonary Hypertension Definition and Hemodynamic Parameters

Pulmonary hypertension is defined by the following hemodynamic criteria measured during right heart catheterization:

• Mean pulmonary arterial pressure (mPAP): ≥25 mmHg at rest 1, 2
• Pulmonary vascular resistance (PVR): >3 Wood units in pre-capillary PH 1, 2
• Pulmonary artery wedge pressure (PAWP):
  • ≤15 mmHg in pre-capillary PH (includes PAH)

  • 15 mmHg in post-capillary PH (includes PH due to left heart disease) 1, 2

Pulmonary Artery Systolic and Diastolic Pressures

While guidelines primarily focus on mean pulmonary arterial pressure for diagnosis, the systolic and diastolic components are important clinical parameters:

Normal Values:

• Pulmonary artery systolic pressure: 15-30 mmHg
• Pulmonary artery diastolic pressure: 4-12 mmHg

In Pulmonary Hypertension:

• Pulmonary artery systolic pressure: Typically >35-40 mmHg
• Pulmonary artery diastolic pressure: Often >15 mmHg

Diagnostic Approach

Right heart catheterization is essential for definitive diagnosis and accurate pressure measurements 2, 3. However, non-invasive screening can be performed with:

• Echocardiography: Can estimate pulmonary artery systolic pressure through tricuspid regurgitation jet velocity. In patients with elevated right ventricular pressure (>35 mmHg), Doppler echocardiography has approximately 80% sensitivity 1

• Electrocardiogram: May show signs of right ventricular hypertrophy and right atrial enlargement in advanced cases 1

Clinical Implications

The presence of elevated pulmonary pressures significantly impacts prognosis:

• 5-year mortality: ~25% for mPAP 19-24 mmHg
• 5-year mortality: ~40% for mPAP ≥25 mmHg 2

Important Considerations

1. Right ventricular function: The presence of right ventricular dysfunction significantly worsens prognosis and requires urgent evaluation 2

2. Classification: Proper classification of PH (Groups 1-5) is essential for appropriate treatment selection 2

3. Diagnostic accuracy: Relying solely on echocardiography without confirmatory right heart catheterization can lead to misclassification 2

4. Treatment approach: Using PAH-specific therapies in non-PAH forms of PH can be harmful, especially in PH due to left heart disease 2

Right heart catheterization remains the gold standard for accurate measurement of pulmonary artery pressures and definitive diagnosis of pulmonary hypertension, allowing for proper classification and treatment planning.