ABSTRACT: To identify features on B-mode ultrasonography (US) prevalent in symptomatic plaques and correlate these findings with histopathologic markers of plaque instability.
Carotid endarterectomy (CEA) plaques from symptomatic and asymptomatic patients with critical stenoses (>70%) were qualitatively assessed using preoperative B-mode US for echolucency and calcific acoustic shadowing. US echolucency was quantitated ex vivo using computerized techniques for gray-scale median (GSM) analysis. Histopathologic correlates for US plaque echolucency (percentage of necrotic core area) and acoustic shadowing (percentage of calcification area) were determined.
Fifty CEA plaques were collected from 48 patients (46 unilateral and two bilateral); 26 of these plaques were from symptomatic patients. Age, degree of stenosis, and atherosclerotic risk factors were similar for the symptomatic and asymptomatic patients. Using preoperative B-mode US, 58%, 35%, and 7% of symptomatic plaques and 18%, 41%, and 41% of asymptomatic plaques were found to be echolucent, echogenic, and calcific, respectively (P < .05). Using ex-vivo B-mode US and GSM analysis, symptomatic plaques were more echolucent (41 +/- 19) than asymptomatic plaques (60 +/- 13), P < .03. A strong inverse correlation was found between the percent plaque necrotic area core and GSM (R = -0.9, P < .001). Percentage of calcification area in plaques with acoustic shadowing was 66% and only 27% in those without acoustic shadowing (P < .05).
Using B-mode US, symptomatic plaques are more echolucent and less calcified than asymptomatic plaques and are associated with a greater degree of histopathologic plaque necrosis. Such features are indicative of plaque instability and should be considered in the decision-making algorithm when selecting patients with high-grade asymptomatic carotid stenosis for intervention.
Journal of Vascular Surgery 09/2005; 42(3):435-41. · 3.21 Impact Factor
ABSTRACT: Increasing use of primary arteriovenous fistulae (pAVFs) is a desired goal in hemodialysis patients (National Kidney Foundation /Dialysis Outcome Quality Initiative guidelines). However, in many instances, pAVFs fail to adequately mature due to ill-defined mechanisms. We therefore investigated pAVFs with color duplex ultrasound (CDU) surveillance 4 to 12 weeks postoperatively to identify hemodynamically significant abnormalities that may contribute to pAVF failure.
From March 2001 to October 2003, 54 upper extremity pAVFs were subjected to CDU assessment before access. A peak systolic velocity ratio (SVR) of >/=2:1 was used to detect >/=50% stenosis involving arterial inflow and venous outflow, whereas an SVR of >/=3:1 was used to detect >/=50% anastomotic stenosis. CDU findings were compared with preoperative vein mapping and postoperative fistulography when available.
Of 54 pAVFs, there were 23 brachiocephalic, 14 radiocephalic, and 17 basilic vein transpositions. By CDU surveillance, 11 (20%) were occluded and 14 (26%) were negative. Twenty-nine (54%) pAVFs had 38 hemodynamically significant CDU abnormalities. These included 16 (42%) venous outflow, 13 (34%) anastomotic, and 2 (5%) inflow stenoses. In seven (18%), branch steal with reduced flow was found. In 35 of 54 (65%) pAVFs, preoperative vein mapping was available and demonstrated adequate vein size (>/=3 mm) and outflow in 86% of cases. Twenty-one fistulograms (38%) were available for verifying the CDU abnormalities. In each fistulogram, the arterial inflow, anastomosis, and venous outflow were compared with the CDU findings (63 segments). The sensitivity, specificity, and accuracy of CDU in detecting pAVF stenoses >/=50% were 93%, 94%, was 97%, respectively.
Before initiation of hemodialysis, an unexpectedly high prevalence of critical stenoses was found in patent pAVFs using CDU surveillance. These de novo stenoses appear to develop rapidly after arterialization of the upper extremity superficial veins and can be reliably detected by CDU surveillance. Turbulent flow conditions in pAVFs may play a role in inducing progressive vein wall and valve leaflet intimal thickening, although stenoses may be due to venous abnormalities that predate AVF placement. Routine CDU surveillance of pAVFs should be considered to identify and correct flow-limiting stenoses that may compromise pAVF long-term patency and use.
Journal of Vascular Surgery 07/2005; 41(6):1000-6. · 3.21 Impact Factor
ABSTRACT: We investigated the utility of color duplex ultrasound (CDU)-derived common femoral artery (CFA) hemodynamics for detecting significant aortoiliac occlusive disease and predicting its severity.
From January 1997 to June 2001, 132 consecutive patients with lower extremity arterial insufficiency underwent both femoropopliteal CDU scanning and aortography with runoff studies. CDU-derived CFA waveform contour (monophasic, biphasic, or triphasic), peak systolic velocity (PSV), and acceleration time were recorded for each patient. Severity of aortoiliac occlusive disease was classified by arteriography into three distinct groups: normal or minimal disease (<50%, group 1), significant focal or diffuse stenoses (>/=50%, group 2), or total occlusion (group 3). Using probability and receiver operating characteristic curve analysis, waveform contour and PSV were compared alone and in combination with the arteriographic groups to identify waveform contours and threshold PSV, which may accurately differentiate the three categories of aortoiliac occlusive disease.
Of 214 limbs available for study, 112 composed group 1, 70 composed group 2, and 32 composed group 3. Concomitant femoropopliteal disease was present in 47% of limbs in group 1, 53% of limbs in group 2, and 34% of limbs in group III. An abnormal CFA waveform contour (monophasic or biphasic) differentiated group 1 from groups 2 and 3, with 95% sensitivity, 89% specificity, 89% positive predictive value (PPV), 95% negative predictive value (NPV), and 92% accuracy. Mean PSV and acceleration time for monophasic and biphasic waveforms were 39 cm/sec +/- 19, 178 msec +/- 36 vs 95 cm/sec +/- 67, 97 msec +/- 31 respectively (P <.05). In differentiating between groups 2 and 3, the specificity, PPV, and accuracy for CFA PSV of </=45 cm/sec alone and for the PSV </=45 cm/sec combined with a CFA monophasic waveform were 89%, 76%, 85% and 97%, 92%, 88%, respectively. Concomitant significant superior femoral artery and bilateral iliac disease did not influence these findings.
CFA PSV 45 cm/s or less combined with a monophasic waveform is highly predictive of ipsilateral iliac occlusion. These results were independent of contralateral iliac and distal superior femoral artery disease. CFA color duplex US scanning may be considered an alternative technique to direct duplex scanning of the aortoiliac segment in patients being evaluated for inflow endoluminal or bypass procedures.
Journal of Vascular Surgery 06/2003; 37(5):960-9. · 3.21 Impact Factor