Sunday, May 11, 2008

Carotid bruits

We're always looking for an easy-to-use, 'crystal ball' of a test that will predict cardiovascular risk. Since we can't actually visualize the blood vessel walls, we use 'surrogate markers' that are more or less associated with unwanted future outcomes like stroke and heart attack.

The carotid arteries are well-placed for easy access as they head upwards through the neck on either side of trachea. Not only does atherosclerotic narrowing in these essential vessels increase risk for embolic stroke (where little bits of clot and cholesterol guck break off from the walls and block the blood supply to parts of the brain), the health of these vessels is a good predictor of overall vascular health.

Thickening of the carotid walls known as intimal-medial thickness or IMT is a known risk factor for heart attack and stroke. Although this can be measured without actually needling these big old arteries, and thank heavens for that, carotid ultrasound technology is not readily available in the average PCP's office. Advancing age, LDL-cholesterol levels, and diastolic blood pressure(1) are good current predictors of IMT thickening(2). These measurements can be used then as surrogate markers raising suspicion that a person rating high in all three areas might well have carotid artery disease.

The latest issue of The Lancet confirms that another test easily performed on aging persons during their annual physical provides additional cardiovascular risk assessment. Around the age of 50 or so, I begin to feel for normal pulsation in the carotid arteries (but not both at once as bilateral pressure on these vessels can induce fainting!) as well as listen with my stethoscope for the unwanted, rhythmic whish of a carotid bruit that occurs as the heart contracts and sends a surge of blood through narrowed old carotids.

Doctors from Walter Reed Medical Center analyzed data from thousands of carotid arteries and their attached humans with respect to risk of heart attack with or without death in follow-up. Those whose carotids hummed at outset were twice as likely to have a heart attack in the 2-7 years that followed, and had nearly thrice the risk of cardiovascular death.

So ask your doc to check up your neck at your next physical.
(1)Diastolic pressure is the lower reading on blood pressure measurement which measures the amount of pressure in your blood vessels as your heart relaxes in preparation for the next beat. The upper or systolic number is the pressure generated as the heart contracts. Diastolic hypertension is also a known risk factor for abnormal thickening of the heart wall.
(2)Davis, PH, et al. Carotid Intimal-Medial Thickness Is Related to Cardiovascular Risk Factors Measured From Childhood Through Middle Age. Circulation. 2001;104:2815-2819.
(3)Pickett, CA, et al. Carotid bruits as a prognostic indicator of cardiovascular death and myocardial infarction: a meta-analysis. The Lancet. 2008; 371:1587-1594.


Anonymous said...

Durn! I've been checking necks for bruits forever. Nice to know there's some science to back it up. Anymore everybody just wants to do US; heaven forbid we actually touch a patient. (I don't think a lot of young docs are too good with hear murmurs, either).

Beverly said...

My doctor always listens to cardiologist too.