What are the limitations 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

The current Doppler probe method has limitations. Limitations include the following:

  • Only changes in flow velocity, rather than absolute velocity or volumetric flow, are measurable

  • The change in flow velocity is directly proportional to changes in volumetric flow only when vessel dimensions are constant at the site of the sample volume

  • Other factors, including left ventricular hypertrophy and myocardial scarring, can also affect CFR

  • Changes in luminal diameter and arterial cross-sectional area during interventions are not reflected in measurements of flow velocity, thus potentially causing underestimation of the true volume flow

Because this technique does not measure absolute coronary blood flow, several indices of flow velocity have been used for assessing the physiologic significance of coronary stenoses. Coronary flow velocity reserve is the ratio of maximum flow velocity to baseline flow velocity.

Patients with a coronary flow velocity ratio of less than 2 typically have other corroborating evidence of myocardial ischemia and improve symptomatically with revascularization. Conversely, patients with a ratio of more than 2 usually lack other objective evidence of myocardial ischemia and have a favorable outcome with conservative management; therefore, flow velocity measurements can be helpful in the treatment of patients with coronary lesions of intermediate severity.


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