NASCET Stenosis Calculator

The NASCET Stenosis Calculator estimates carotid artery stenosis percentage using angiographic measurements of the narrowest and normal vessel diameters. This tool helps medical professionals and students accurately assess stroke risk and determine the need for surgical intervention. Whether you are evaluating a symptomatic patient or monitoring disease progression, this calculator provides a standardized and clinically validated assessment essential for treatment planning.

Enter the narrowest diameter of the stenotic segment measured on angiography
Enter the diameter of the normal artery distal to the stenosis

How Carotid Artery Stenosis Percentage Is Calculated

Carotid Artery Stenosis Percentage represents the degree of narrowing in the carotid artery, often caused by plaque buildup. The standard method used is the NASCET (North American Symptomatic Carotid Endarterectomy Trial) formula, which compares the tightest point of the artery to a healthy section further down.

Stenosis (%) = [(1 - (Narrowest Diameter / Normal Diameter)) × 100]

Where:

  • Narrowest Diameter = The tightest point of the blockage
  • Normal Diameter = The width of the healthy artery past the blockage

To find this, first measure the narrowest part of the blockage. Next, measure the diameter of the normal artery just beyond the narrowed area. By dividing the narrow width by the normal width, you determine the remaining open space. This method is highly credible because it uses a stable reference point, ensuring accuracy for clinical decisions.

What Your Carotid Artery Stenosis Percentage Means

This percentage tells you how much the artery is blocked, which directly relates to the risk of stroke. A higher percentage means less blood flow to the brain and a greater chance of dangerous complications like transient ischemic attacks.

Clinical Scenarios

  • Mild Stenosis (Less than 50%): Usually managed with medical therapy like anti-platelet medications and statins, along with lifestyle changes to strictly control blood pressure and cholesterol.
  • Moderate Stenosis (50% to 69%): Treatment depends heavily on specific symptoms and patient history; doctors may recommend surgery if the patient has had previous stroke warning signs or other risk factors.
  • Severe Stenosis (70% or greater): Strongly indicates the need for carotid endarterectomy surgery to clear the blockage and prevent future strokes, especially in symptomatic patients.

Important: This calculator is for informational purposes only and does not replace professional medical advice, diagnosis, or treatment. Always consult with a qualified healthcare provider for clinical decisions.

Regular monitoring with follow-up imaging is recommended to track any changes in the stenosis over time.