Duplex carotid scan in hypertensive patients at the Rivers State University Teaching Hospital Port Harcourt, Nigeria

Abstract

Background: Carotid vascular scan has proven a very valuable tool in assessing atherosclerotic source of large vessel thromboembolic stroke. The stroke  burden is high in Nigeria and globally, it corresponds to the prevalence of hypertension. Hypertension is the leading cause of Ischemic stroke. The  relationship of hypertension and carotid vascular parameters will be an interesting study. Duplex carotid vascular scan is non-invasive, cheap, and readily  available. This study set out to evaluate the effect of hypertension on carotid vascular parameters by comparing carotid artery parameters between a  hypertensive population and that from normal individuals.

Method: Hypertensive nondiabetics attending clinics at the Rivers State University Teaching Hospital, from January 2021 to October 2021, were recruited  for the study and carotid artery parameters from normal, non-hypertensive and non-diabetic data was compared after carefully matching for body mass  indices. A protocol was developed of duplex vascular parameters of the left common carotid (LCC), right common carotid artery (RCC), left the internal  carotid (LIC), and right internal carotid artery (RIC). This protocol was used to assess the hypertensives and values obtained were compared to that of a  normal Nigerian Population. Peak Systolic Velocity (PSV) End diastolic velocity (EDV) the Resistivity index (RI), the vessel diameters and carotid Intima  Media Thickness (cIMT). Data was collected on excel spreadsheet and analyzed using Statistical Package for the Social Sciences (SPSS) 23.

Results: Eighty-  one (81) hypertensives who met the inclusion criteria and data for fifty (50) apparently normal individuals was utilized. The mean age  ±SD for the hypertensive population: normal was 57.26 ± 10.53yrs: 48.67 ± 7.11yrs. Mean systolic blood pressures ±SD of hypertensive population:  normal was 167.46 ± 17.73mmHg: 129 ± 11.29mmHg, mean diastolic blood pressure ±SD for hypertensive: normal was 88.63 ± 12.57mmHg: 76.04 ± 8.15  mmHg. There was no significant difference in their BMI. The left common carotid showed statistically significant difference in its IMT, and diameter when  compared with the normal population and the left internal carotid showed significantly larger vessel diameter and increased IMT when compared to the  normal parameters. On the right there was a significantly larger vessel diameter of the RCC and increased IMT for both RCC and RIC. Carotid doppler  velocities showed higher EDV of the left internal carotid artery and S/D ratio was significantly higher in the LCC, LIC and RCC arteries. Bivariate analysis  using the Pearson correlation coefficient revealed a negative correlation at significant at 0.01level (2 tailed) between SBP and the PSV (-441, 0.002) and  EDV (-365, 0.011) of the Left Internal Carotid artery. There was also a positive correlation of the EDV and the left internal carotid IMT (0.385,0.009).  However, on the RCC and RIC there was no correlation with blood pressures in our study population. The blood pressure affected the left internal Carotid  artery more than the left common carotid artery. Forty-three (53.09%) of the hypertensive population had left common cIMT > 0.09cm. Forty-one (50.0%)  had left internal cIMT >0.09cm. Forty-five (55.56%) of the hypertensive group had the right common cIMT > 0.09cm and right internal carotid 38(46.91%)  had cIMT > 0.09cm. Twelve (12) and (15.39%) had plaques of varying echogenicity. A notable finding was a higher peak velocity relative to end diastolic  velocity (high SD ratio) noted at points of stenosis which could be doppler pointer to stenosis in the especially in the echolucent plaques.

Conclusion:  Hypertension affects the structure and blood flow across the carotid vessels significantly as shown in its impact on PSV, EDV and S/D and there is need to  evaluate the role of doppler parameters as surrogates of cardiovascular markers.