Are your patients at risk for cardiovascular disease?

Have you ever found yourself wondering if there were more to helping your patients avoid heart disease than targeting LDL and encouraging a healthy lifestyle?

Many patients suffering the early and intermediate stages of atherosclerosis show no outward signs of risk or symptoms of the disease. What if you could look inside your patients' carotid arteries to see if there are signs of the disease and how advanced or severe it may be? What if you could measure the degree of inflammation in the arterial wall or the size of the plaque that may contribute to the most common cause of death in America, heart disease?

Measuring the thickness of the intima and media layers (intima-media thickness, or IMT) of the carotid artery wall is one way to assess the cardiovascular health of your patients. This non-invasive procedure gives you another piece of the diagnostic puzzle that can help you assess disease presence and progression before your patient presents with acute symptoms.

The carotid artery wall is made up of three layers: the intima, a thin endothelial layer that borders the blood-filled lumen; the adventitia, the outer layer that borders the surrounding tissue; and the media, the layer between these inner and outer walls. Because of the easily discernable lumen-intima and media-adventitia boundaries, the intima and media layers are generally assessed together, giving us the IMT measurement. As cardiovascular disease progresses, it often presents as a visible thickening of the IMT as well as the presence of visible fibrous or calcified plaques.

IMT measurements using ultrasound have been performed since the mid-1980s. Using B-mode (brightness mode) ultrasound, a clinician can easily and non-invasively acquire images of the carotid artery wall for analysis, typically in the region immediately proximal to the bifurcation. Upon examination via ultrasound, the adventitia shows up as a bright, white layer and the blood-filled lumen shows up as a black area, allowing the clinician to isolate the area of interest in between, the IMT. In the protocol used in SonoSite's development of the software, an experienced ultrasound technician or physician can complete the initial ultrasound exam and quick review of images within 10-15 minutes. If there is indication of disease, the images can be stored for further analysis using automated edge-detection technology, like SonoSite's SonoCalc™ IMT. This analysis allows the clinician to look at several images of the artery wall, and can include a comparison of the patient's IMT measurement against published population data to generate a more specific risk profile report.

Recent studies have shown that looking at a patient's carotid artery as a predictor of the condition of one of their coronary arteries is as good as looking at one coronary artery and predicting the condition of another. (Crouse)
Using IMT as a method of understanding disease progression can provide incremental and valuable understanding to a physician attempting to make a treatment decision, in addition to information yielded by more traditional measures of cardiovascular disease progression like cholesterol levels and body mass assessment.

Assessment of a patient's IMT, in connection with assessment of other factors (lipid profile, family history, body mass index, etc.), can give the clinician a more complete picture of the actual cardiovascular risk present in a patient.