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THE R) AND L) COMMON CAROTID INTIMAL MEDIAL THICKNESS MAY BE EXPLAINED BY THE DIFFERENCES IN THEIR VELOCITIES

THE   R) AND L) COMMON CAROTID INTIMAL MEDIAL THICKNESS MAY BE EXPLAINED BY THE DIFFERENCES IN THEIR VELOCITIES

Author Block MF Matangi, DW Armstrong, M Nault, D Brouillard, Kingston, Ontario

BACKGROUND: It is well documented that L) common carotid artery (CCA) intimal medial thickness (IMT) is mildly increased when compared to R) CCA IMT, even in individuals with completely normal carotid studies. We believe there may be an anatomical explanation. The purpose of our investigation was to determine whether or not there was a difference in CCA velocities between L) and R) CCA that may account for the difference in CCA IMT between the two sides.

METHODS: CAROTIDfile the carotid duplex imaging module of CARDIOfile, our cardiology database was searched for all patients who had carotid studies with all the necessary data points. All carotid studies were interpreted using Intersocietal Commission for Accredited Vascular Laboratory (ICAVL) imaging and velocity criteria. Patients were separated into those with an ICA stenosis as defined by ICAVL criteria, those without ICA stenosis but who have an abnormal IMT >1.00mm and those without an ICA stenosis who had a normal IMT ≤1.0mm. Statistics were performed using the unpaired t test. The level of significance was adjusted using the Bonferroni correction for multiple comparisons.
RESULTS: See Table 1.

Table 1
  ICA stenosis 1-100% No ICA stenosis No ICA stenosis and IMT <1.0mm
N 977 435 335
R) CCA IMT (mm) 1.21±0.62 0.80±0.23 0.72±0.14
L) CCA IMT (mm) 1.34±0.69 0.84±0.25 0.74±0.14
P value <0.0001 <0.005 <0.01
R) CCA PSV (cm/sec) 79.3±20.8 84.1±18.1 85.3±18.1
L) CCA PSV (cm/sec) 86.7±24.8 88.8±17.6 89.5±17.3
P value <0.0001 <0.0001 <0.0001


CONCLUSION: Irrespective of the degree (if any) of ICA stenosis, the L) CCA IMT is consistently thicker than the R) CCA IMT. This difference is highly statistically significant. Similarly there is a highly statistically significant difference in the distal CCA peak systolic velocity (PSV). The difference in velocity most likely has an anatomical explanation. The lower PSV in the R) CCA is most likely due to a fall in CCA velocity after the origin of the R) subclavian. We postulate that the higher velocity in the L) CCA leads to increased sheer forces and increased risk of L) CCA intimal damage over time. The end result being slightly increased L) CCA intimal medial thickness