PVD is NOT Essential for PVR
No, Peripheral Vascular Disease (PVD) is not essential for Pulmonary Vascular Resistance (PVR). These are distinct entities affecting different vascular beds—PVD refers to systemic arterial disease (typically atherosclerotic disease of peripheral arteries), while PVR is a hemodynamic measurement of resistance in the pulmonary circulation.
Understanding the Terminology Distinction
The confusion likely stems from the term "PVD" being used in different contexts:
Peripheral Vascular Disease (PVD): Refers to atherosclerotic disease affecting systemic arteries, particularly lower extremities 1, 2
Pulmonary Vascular Disease (PVD): A completely separate entity referring to pathologic changes in the pulmonary vasculature that can lead to elevated PVR 1
When discussing pulmonary hypertension, "PVD" in the literature refers to pulmonary vascular disease, not peripheral vascular disease. This is a critical distinction that prevents clinical confusion.
Pulmonary Vascular Disease and PVR Relationship
When PVD (Pulmonary) Causes Elevated PVR
Pulmonary vascular disease is characterized by structural and functional abnormalities of the pulmonary vasculature that directly increase PVR 1:
- Decreased vascular growth: Reduced small pulmonary arteries and altered distribution within lung interstitium 1
- Increased vascular tone and vasoreactivity: Hypertensive remodeling and abnormal vasoconstriction 1
- Reduced alveolar-capillary surface area: Limits vascular recruitment and increases resistance 1
Clinical Contexts Where Pulmonary PVD Elevates PVR
In Bronchopulmonary Dysplasia (BPD): Abnormalities of lung circulation are "more broadly related to PVD resulting from decreased vascular growth, which also contributes to disease pathogenesis and abnormal cardiopulmonary physiology" 1. High PVR in BPD causes poor RV function, impaired cardiac output, limited oxygen delivery, and increased pulmonary edema 1.
In Congenital Heart Disease: The state of the pulmonary vascular bed strongly influences outcomes, as "small elevations of PVR can markedly impair cardiac performance" 1. Determination of baseline hemodynamics and PVR is crucial for surgical candidacy 1.
In Left Heart Disease: Pulmonary vascular disease in LHD is associated with combined post- and pre-capillary pulmonary hypertension (CpcPH), defined by PVR ≥3.0 Wood Units, and is linked to worse RV-PA uncoupling, greater ventricular interaction, and more severe impairments in cardiac output 3.
Elevated PVR Without Pulmonary Vascular Disease
PVR can be elevated without structural pulmonary vascular disease in conditions where:
- Increased pulmonary blood flow occurs without vascular remodeling (high-flow states) 1
- Elevated left atrial pressure causes passive pulmonary hypertension without fixed vascular changes (isolated post-capillary PH) 3
- Acute vasoconstriction from hypoxia or acidosis transiently increases PVR 1
Clinical Implications
The distinction matters for treatment decisions: Patients with elevated PVR due to structural pulmonary vascular disease may require PAH-specific therapy and have different prognoses compared to those with elevated PVR from passive congestion alone 1, 3.
Cardiac catheterization is essential to distinguish between elevated PVR with and without pulmonary vascular disease, measuring transpulmonary gradient, PVRI, and assessing vasoreactivity 1.
Common pitfall: Assuming all elevated PVR represents fixed pulmonary vascular disease—acute vasodilator testing can identify reversible components 1.