The pulsatility index is a quantitative measure reflecting the resistance to blood flow within a vessel. It is derived from the difference between the peak systolic velocity and the end-diastolic velocity, divided by the mean velocity during a cardiac cycle. For instance, if peak systolic velocity is 100 cm/s, end-diastolic velocity is 20 cm/s, and the mean velocity is 60 cm/s, the resulting index would be (100-20)/60 = 1.33.
This hemodynamic parameter serves as an indicator of downstream vascular resistance. Elevated values often suggest increased resistance, potentially due to vasoconstriction or distal obstructions. Its utility lies in assessing vascular health, monitoring disease progression, and evaluating the effectiveness of therapeutic interventions. Historically, its application in vascular studies has provided valuable insights into circulatory dynamics.
