Pre-capillary pulmonary hypertension – hemodynamic profile

Pre-capillary pulmonary hypertension denotes raised pressure in the pulmonary circulation whose cause lies within the pulmonary vasculature itself. Under the 2022 ESC/ERS guideline three criteria must be met simultaneously: a mean pulmonary artery pressure above 20 mmHg, a pulmonary artery wedge pressure of at most 15 mmHg, and a pulmonary vascular resistance above 2 Wood units. The 2022 guideline lowered two thresholds: mPAP from 25 to 20 mmHg and PVR from 3 to 2 Wood units. The low PCWP indicates the left heart is not the cause.

For educational use only. Not for clinical use.

Hemodynamic profile

ParameterDirectionTypicalNormal range
mPAP↑> 20 mmHg< 20
PCWP→≤ 15 mmHg6-15
PVR↑> 2 WU (> 160 dyn·s·cm⁻⁵)< 160 (< 2 WU)
ZVD→normal, rising over time2-6
CI→normal, reduced in late stages2.5-4.0

Differentiation

Differentiate fromDiscriminating parameterExplanation
Post-capillary pulmonary hypertensionPCWPPCWP separates the two forms: up to 15 mmHg is pre-capillary, above that post-capillary. This single measurement decides whether the cause lies in the pulmonary vasculature or the left heart.
Right heart failureZVDPre-capillary pulmonary hypertension is the cause, right heart failure the consequence. A rising CVP with a falling PAPI indicates the right ventricle can no longer meet the afterload.

Causes

  • Pulmonary arterial hypertension, idiopathic or heritable
  • Connective tissue disease, particularly systemic sclerosis
  • Chronic thromboembolic pulmonary hypertension
  • Chronic lung disease such as COPD or pulmonary fibrosis
  • Congenital heart disease with left-to-right shunt
  • Portopulmonary hypertension

Clinical context

Exertional dyspnoea, reduced exercise capacity and, in advanced stages, syncope dominate the picture. Hemodynamically the decisive point is that the right ventricle must work against a persistently raised resistance; as long as it adapts, cardiac index and CVP remain normal. A falling cardiac index with rising CVP and declining PAPI marks the transition to right heart failure and carries an adverse prognosis. Pulmonary vascular resistance is the parameter that reflects the burden on the pulmonary vasculature most directly, since it relates pressure to flow.

Frequently asked questions

How is pre-capillary pulmonary hypertension defined?
Per ESC/ERS 2022 by an mPAP above 20 mmHg, a PCWP of at most 15 mmHg and a PVR above 2 Wood units, equivalent to 160 dyn·s·cm⁻⁵. All three criteria must be met simultaneously.
What changed with the 2022 guideline?
The threshold for mean pulmonary artery pressure was lowered from 25 to above 20 mmHg and the pulmonary vascular resistance cutoff from 3 to 2 Wood units, so that milder forms are captured earlier.
How do you distinguish pre- from post-capillary pulmonary hypertension?
Solely by the PCWP. Up to 15 mmHg the form is pre-capillary, above 15 mmHg post-capillary. PVR then decides within the post-capillary group whether an additional pre-capillary component is present.
What does a PVR above 2 Wood units mean?
It indicates that resistance within the pulmonary vasculature itself is raised, so the pressure elevation is not explained by increased flow or backward pressure from the left heart alone. Two Wood units correspond to 160 dyn·s·cm⁻⁵.
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