nPVR, or normalized pulmonary vascular resistance, is a hemodynamic parameter used to assess the resistance encountered by blood flowing through the pulmonary circulation. It is calculated by dividing the total pulmonary vascular resistance by the pulmonary artery pressure, allowing for a comparison of resistance levels regardless of changes in pressure. nPVR is particularly useful in evaluating conditions like pulmonary hypertension and heart failure, helping to guide treatment decisions and monitor disease progression.