Screening for High-grade Carotid Stenosis Using a Portable Ultrasonography Instrument

Risk Factors for Carotid Artery Stenosis in Chinese Patients Undergoing Coronary Artery Bypass Graft Interventions

Current guidelines established in the USA and Europe for coronary artery bypass graft (CABG) suggest that patients ≥65 and ≥70 years of age, or with certain atherosclerotic-risk factors, should be screened preoperatively for extracranial carotid artery stenosis (CAS) to assess their risk of perioperative stoke. We sought factors that should be taken into consideration when treating Chinese CABG patients using CABG guidelines based on an analysis of CAS in a large cohort of Chinese CABG patients. We analyzed data for 1558 Chinese CABG patients who were screened preoperatively for CAS using duplex ultrasonography at a single institution. We defined significant and severe CAS as ≥50% and ≥70% stenosis, respectively, in one or more common or internal carotid arteries. We investigated the prevalence of CAS, the incidence of perioperative stroke, and the risk factors for CAS in the CABG cohort. The prevalence of CAS in the CABG cohort was 21.2%. Multivariate stepwise logistic regression analysis showed that an age ≥50 years and a history of smoking (odds ratios = 8.36 and 1.83, respectively) were independent risk factors for CAS (P < 0.05 for both). The incidence of perioperative stroke among CABG patients with significant or severe CAS was significantly higher (2.4% and 2.9%, respectively) than in CABG patients with <50% stenosis (0.5%; P = 0.004 and 0.029, respectively). Chinese CABG patients with a history of smoking or ≥50 years of age should undergo preoperative screening for CAS to assess their risk of perioperative stroke.

Power M-Mode Doppler and Single-Gate Spectral Analysis Using a 2-MHz Pulsed-Wave Doppler Transducer to Directly Detect Cervical Internal Carotid Artery Stenosis

BACKGROUND AND PURPOSE

We hypothesized that direct cervical investigation with Power M-Mode Doppler (PMD) combined with single-gate Doppler spectral analysis (SGDSA) using a 2-MHz pulsed-wave Doppler transducer would show reasonable accuracy parameters when compared with standard color-coded carotid duplex ultrasound (CDU).

METHODS

We prospectively screened for cervical internal carotid artery (ICA) stenosis by direct observation using a 2 MHz PMD/SGDSA device. PMD identified the artery (location, depth, flow direction) and SGDSA assessed waveform; peak systolic, end diastolic, and mean flow velocities (MFV) of the common carotid artery; cervical ICA proximally and distally; and external carotid artery. Diagnostic accuracy was compared with concurrent carotid duplex ultrasound. The continuity principle was applied using the proximal/distal cervical ICA MFV ratio.

RESULTS

We examined 456 vessels (228 patients). Using ICA proximally/ICA distally MFV ratio of 1.5 or greater or absence of ICA signature, for 40% to 59% or greater stenosis (including occlusions), sensitivity was 75.4%, specificity 99.8%, positive predictive value 97.7%, negative predictive value 96.6%, and accuracy 96.7%. For MFV ratio 1.6 or greater or absence of ICA signature and 60% to 79% or greater stenosis (including occlusions), sensitivity was 92.3%, specificity 98.1%, positive predictive value 81.8%, negative predictive value 99.3%, and accuracy 97.6%.

CONCLUSIONS

Use of combined PMD and SGDSA to directly observe the extracranial ICA is reasonably accurate compared with carotid duplex ultrasound. Using the MFV ratio of proximal/distal extracranial ICA improves accuracy parameters and provides a quick and effective bedside screen for ICA stenosis. This novel technique should be considered part of the standard PMD/transcranial Doppler examination.