What is the role of Doppler velocity probes in the workup of coronary artery atherosclerosis?

Updated: Apr 09, 2021
  • Author: Sandy N Shah, DO, MBA, FACC, FACP, FACOI; Chief Editor: Yasmine S Ali, MD, MSCI, FACC, FACP  more...
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Answer

Doppler velocity probes use a Doppler flow meter, which is based on the principle of the Doppler effect. This is the most widely applied technique for measuring coronary flow in humans. High-frequency sound waves are reflected from moving red blood cells and undergo a shift in sound frequency proportional to the velocity of the blood flow.

In pulsed-wave Doppler methods, a single piezoelectric crystal can transmit and receive high-frequency sound waves. These methods have been successfully applied in humans by using miniaturized crystals fixed to the tip of catheters. Technological developments have further miniaturized steerable 12-MHz Doppler guide wires to a diameter of 0.014 inches. Flow to a stenosis can therefore be assessed distally and proximally. The Doppler guidewire measures phasic flow velocity patterns and tracks linearly with flow rates in small, straight coronary arteries.

Indications for Doppler velocity probe use include determining the severity of intermediate stenosis (40-60%) and evaluating whether normal blood flow has been restored after percutaneous transluminal coronary angioplasty (PTCA).

The use of smaller Doppler catheters allows measurement of selective coronary artery flow velocity. By noting the increase in flow velocity following administration of a strong coronary vasodilator, such as papaverine or adenosine, the CFR can be defined. CFR provides an index of the functional significance of coronary lesions that obviates some of the ambiguity of anatomical description.


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