What are the two flow characteristics that indicate arterial stenosis?

The indication of arterial stenosis is closely associated with how blood flow behaves in relation to a narrowed segment of a blood vessel. The correct choice highlights two key flow characteristics: focal acceleration of velocities and distal turbulence.

When stenosis occurs in an artery, the constriction creates a localized area where blood flow speeds up due to the reduced diameter affecting flow continuity. This is referred to as focal acceleration of velocities, and is a critical indicator because it reflects how constricted the artery is. As the blood attempts to pass through the narrowing, it gains velocity in that region.

Additionally, distal turbulence is observed further downstream from the point of stenosis. Under normal conditions, blood flows smoothly in laminar patterns. However, the presence of turbulence indicates disturbed flow caused by the abrupt change in velocity and the characteristics of blood flow after it passes through a narrowed section. This turbulence can be visualized through Doppler ultrasound and provides further evidence of significant stenosis.

The other choices do not accurately represent these characteristics in relation to stenosis. For example, increased diastolic flow might suggest a different pathology, rather than indicating stenosis. Similarly, high resistance flow typically occurs in healthy peripheral arteries rather than in stenotic conditions where flow becomes more representative of lower resistance patterns