Fast Five Quiz: Coronary Artery Atherosclerosis

Yasmine S. Ali, MD

Disclosures

November 11, 2019

Coronary angiography was the first available in vivo assessment of the coronary arteries. In this technique, an iodinated contrast agent is injected through a catheter placed at the ostium of the coronaries. The contrast agent is then visualized through radiographic fluoroscopic examination of the heart. Coronary angiography remains the criterion standard for detecting significant flow-limiting stenoses that may be revascularized through percutaneous or surgical intervention.

For the diagnosis of obstructive CAD, 82Rb PET appears to be superior to 99mTc-based SPECT. In a systematic review of studies that used 82Rb PET or 99mTc SPECT, with coronary angiography as a reference standard, PET and SPECT had sensitivities of 90% and 85%, respectively, and specificities of 88% and 85%, respectively. PET had even greater superiority when patients with a low likelihood ratio were excluded.

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. 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. 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 coronary flow reserve.

  • 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.

EBCT is a noninvasive method of evaluating calcium content in the coronary arteries. Healthy coronary arteries lack calcium. As atherosclerotic plaques grow, calcium accumulates because of a perpetuating inflammatory process or the healing and scarring induced by this process. EBCT is currently used as a screening test in asymptomatic patients and as a diagnostic test for obstructive CAD in symptomatic patients, although experts in the field have reached no consensus regarding indications for its use.

Read more about the workup of coronary atherosclerosis and related conditions.

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