Which of the following can cause falsely elevated velocities during a carotid exam?

Falsely elevated velocities during a carotid exam can occur due to tortuous vessels. When the carotid artery is significantly curved or has multiple bends, the ultrasound beam may not align optimally with the direction of blood flow. This misalignment can create an angle of incidence that results in an artificially high measurement of velocity.

In more straightforward terms, as blood travels through a tortuous segment, it may accelerate or create an apparent increase in velocity due to changes in flow dynamics, even in the absence of true stenosis or pathological changes. This effect is particularly important to recognize to ensure accurate assessments of carotid artery disease.

In contrast, other factors, such as increased sample size, ascending aortic flow, and low heart output, may have varying impacts on velocity readings but do not typically cause an elevation due to the intrinsic anatomy and flow characteristics of the carotid arteries themselves. Understanding the physics of ultrasound and blood flow, along with anatomical considerations like vessel tortuosity, is crucial for accurate interpretation of carotid Doppler studies.