Does a mean pulmonary artery pressure of 70 mmHg with a pulmonary artery wedge pressure of 21 mmHg and a normal left ventricular end‑diastolic pressure of 12 mmHg, in the absence of mitral valve disease or left atrial enlargement, meet the hemodynamic criteria for Group 2 pulmonary hypertension?

Hemodynamic Diagnosis of Group 2 Pulmonary Hypertension

No, these hemodynamics do not meet diagnostic criteria for Group 2 pulmonary hypertension because the PAWP of 21 mmHg exceeds the diagnostic threshold of ≤15 mmHg required for Group 2 PH, and the discrepancy between PAWP (21 mmHg) and LVEDP (12 mmHg) indicates unreliable wedge pressure measurement that requires direct left ventricular pressure assessment. 1

Critical Hemodynamic Discrepancy

The 9 mmHg difference between your PAWP (21 mmHg) and LVEDP (12 mmHg) represents a significant measurement error that invalidates the PAWP reading. 1

• When PAWP is unreliable or discrepant with clinical findings, direct left heart catheterization to measure LVEDP is recommended. 1
• The European Society of Cardiology guidelines specifically state that when measurement of PAWP is unreliable, left heart catheterization should be considered to measure LVEDP. 1
• This discrepancy suggests technical issues with wedge pressure measurement, such as improper catheter position, overwedging, or pulmonary vein obstruction. 2

Correct Diagnostic Classification Using LVEDP

Using the accurate LVEDP of 12 mmHg (rather than the erroneous PAWP of 21 mmHg), this patient has:

• Mean PAP: 70 mmHg (severely elevated)
• LVEDP: 12 mmHg (normal, ≤15 mmHg)
• This defines pre-capillary pulmonary hypertension (Group 1,3,4, or 5), NOT Group 2 PH. 1

Hemodynamic Definitions for Group 2 PH

Group 2 PH (post-capillary pulmonary hypertension) requires ALL of the following criteria:

• Mean PAP ≥25 mmHg (older definition) or >20 mmHg (2022 definition) 1, 3, 4
• PAWP >15 mmHg (this is the defining feature of post-capillary PH) 1, 3, 4
• The elevated PAWP reflects backward transmission of elevated left heart pressures 3, 4, 5

Your patient's true LVEDP of 12 mmHg excludes Group 2 PH by definition. 1

Subclassification of Group 2 PH (When Criteria Are Met)

If PAWP were truly >15 mmHg, Group 2 PH is further classified as:

• Isolated post-capillary PH (IpcPH): DPG <7 mmHg and/or PVR ≤3 Wood units 1, 3, 4
• Combined pre- and post-capillary PH (CpcPH): DPG ≥7 mmHg and/or PVR >3 Wood units 1, 3, 4

Calculate PVR to Determine Pre-Capillary Component

Using the correct LVEDP of 12 mmHg:

• PVR = (mPAP - LVEDP) / Cardiac Output
• PVR = (70 - 12) / CO = 58 / CO 2
• If cardiac output is 5 L/min: PVR = 11.6 Wood units (severely elevated, indicating pre-capillary disease) 2
• Normal PVR is <2-3 Wood units; PVR >3 Wood units defines pre-capillary pulmonary vascular disease 1, 2

Clinical Implications of This Hemodynamic Profile

This patient has severe pre-capillary pulmonary hypertension with:

• Markedly elevated mean PAP (70 mmHg) with normal left heart filling pressures (LVEDP 12 mmHg) 1
• Absence of mitral valve disease and left atrial abnormality further supports pre-capillary etiology 1
• This hemodynamic profile suggests Group 1 (pulmonary arterial hypertension), Group 3 (lung disease), Group 4 (chronic thromboembolic PH), or Group 5 (miscellaneous) 1

Diagnostic Algorithm Moving Forward

Step 1: Repeat right heart catheterization with careful attention to wedge pressure technique 1, 2

• Zero the transducer at mid-thoracic line 2
• Confirm proper wedge position with blood gas showing arterialized blood 2
• Measure at end-expiration during spontaneous breathing 2
• If PAWP remains discrepant, directly measure left atrial pressure or LVEDP 1

Step 2: If LVEDP remains ≤15 mmHg, pursue workup for pre-capillary PH 1

• Ventilation-perfusion scan to exclude chronic thromboembolic disease (Group 4) 1
• High-resolution chest CT to evaluate for interstitial lung disease (Group 3) 1
• Serologic testing for connective tissue disease (Group 1) 1
• Consider vasoreactivity testing if idiopathic PAH is suspected 1

Step 3: Echocardiographic features that would suggest occult left heart disease despite normal LVEDP 1

• Left atrial enlargement >4.2 cm 1
• Increased E/e' ratio suggesting diastolic dysfunction 1
• Concentric left ventricular hypertrophy 1
• However, your patient lacks mitral valve disease and left atrial abnormality, making occult Group 2 PH unlikely 1

Common Pitfalls in PAWP Measurement

Several technical factors can cause falsely elevated PAWP readings:

• Overwedging: Balloon inflation in too distal a position creates artificially high pressure 2
• Catheter tip position: Measurements in West lung zones 1 or 2 overestimate left atrial pressure 2
• Respiratory variation: Failure to measure at end-expiration causes inaccurate readings 2
• V-wave inclusion: Large V-waves in the wedge tracing can elevate mean PAWP without reflecting true LVEDP 2

The 9 mmHg gradient between your PAWP and LVEDP strongly suggests one of these technical errors occurred. 1, 2

Why Normal LVEDP Excludes Group 2 PH Despite Elevated PAWP

The fundamental pathophysiology of Group 2 PH is passive backward transmission of elevated left heart pressures into the pulmonary circulation. 3, 4, 5

• If LVEDP is normal (12 mmHg), there is no elevated left heart pressure to transmit backward 3, 4
• The absence of mitral valve disease eliminates valvular obstruction as a cause of elevated left atrial pressure with normal LVEDP 1
• The absence of left atrial abnormality makes left atrial myopathy or restrictive physiology unlikely 1
• Therefore, the erroneous PAWP of 21 mmHg must be disregarded in favor of the directly measured LVEDP of 12 mmHg 1