Maria Fabrizia Giannoni

Contrast Carotid Ultrasound for the Detection of Unstable Plaques with Neoangiogenesis: A Pilot Study

OBJECTIVES To evaluate whether contrast ultrasonography can be used to distinguish asymptomatic from symptomatic carotid plaques and provide insight into underlying pathophysiological differences. DESIGN Contrast carotid ultrasound was performed in both symptomatic and asymptomatic patients referred for carotid endarterectomy. MATERIALS AND METHODS Of 77 consecutive patients referred for carotid artery evaluation, 64 underwent carotid endarterectomy for asymptomatic cerebrovascular disease and 9 underwent urgent surgery for acute neurological deficits with hemiparesis. The endarterectomy specimens were assessed immunohistologically. RESULTS In all 9 patients undergoing urgent surgery, contrast ultrasonography showed the accumulation of diffuse microbubble contrast at the base of the carotid plaque. This pattern was observed only in 1/64 of the patients undergoing surgery for asymptomatic carotid disease. Immunohistologically staining of the endarterectomy specimens showed that the area of microbubble contrast at the base of the symptomatic plaques was associated with an increased number of small diameter (20-30 microm) microvessels staining for vascular endothelial growth factor (VEGF). CONCLUSIONS Contrast carotid ultrasonography may allow the identification of microvessels with neoangiogenesis at the base of carotid plaques, and differentiate symptomatic from asymptomatic plaques.

Detection of Carotid Adventitial Vasa Vasorum and Plaque Vascularization With Ultrasound Cadence Contrast Pulse Sequencing Technique and Echo-Contrast Agent

Background and Purpose— Adventitial vasa vasorum and plaque vascularization have been established as predictors of unstable atheromasic lesions in cerebro- and cardiovascular patients. Ultrasound contrast agents provide reliable information on tissue perfusion and microcirculation. We used contrast ultrasound duplex scanning to identify carotid plaque vascularization. Methods— Contrast carotid duplex scanning was performed in 23 patients with plaques of different degree of stenosis and echogenicity. Results— Plaque vascularization was detected in the fibrous and fibro-fatty tissue and not observed in the calcific nor in the necrotic and hemorrhagic tissue. Constantly, a small vessel was observed under ulcerations. Conclusions— Carotid contrast ultrasound imaging appears to be an emerging technique for identifying plaque angiogenesis. Further studies are needed to clarify the role of plaque angiogenesis for assessing cerebrovascular risk and to monitor effects of therapies aimed to plaque remodelling.

Post-carotid endarterectomy hyperperfusion syndrome: Preliminary observations for identifying at risk patients by transcranial doppler sonography and the acetazolamide test

Patients at risk of hyperperfusion syndrome after carotid endarterectomy are often severely hypertensive and have a high grade internal carotid artery stenosis with disordered autoregulation due to a loss of reserve capacity (RC). Cerebral RC can be studied by sophisticated and expensive technical devices (SPECT, PET). Recently it has been demonstrated that the transcranial Doppler (TCD) and acetazolamide provocation test can be used to assess RC. From September 1991 to January 1992, 36 patients were studied by the TCD and acetazolamide test prior to carotid endarterectomy to identify patients at high risk of the hyperperfusion syndrome. Preoperatively, the patients were studied by TCD at rest and after vasolidation with acetazolamide 1 g intravenously (i.v.). Mean blood flow velocity on the middle cerebral artery (MCAv) was recorded for the following 20 min at 5 min intervals. MCAv at rest was 49 +/- 17 cm/s. After acetzaolamide infusion in 33 patients (92%), the mean MCAv was 62 +/- 19 cm/s with an increase of 19 +/- 13 cm/s (normal RC). In three patients (8%), the mean MCAv was 43 +/- 22 cm/s with a decrease of -6 +/- 3 cm/s with respect to base values (reduction of RC). (t = 3.30; p = 0.0022). All these patients were hypertensive (BP > 180/100 mmHg) and had a carotid artery stenosis > 90%. Postoperatively, the three patients with reduction of RC complained of homolateral headache. TCD showed a mean MCAv of 67 +/- 17 cm/s, an increase compared to the preoperative rest values of 17 +/- 8 cm/s, the 33 patients with normal RC showed a mean change in MCAv -2 +/- 12 cm/s.(ABSTRACT TRUNCATED AT 250 WORDS)

Contrast-Enhanced Ultrasound Imaging for Aortic Stent-Graft Surveillance

Purpose: To compare unenhanced and enhanced ultrasound imaging to computed tomographic angiography (CTA) or magnetic resonance angiography (MRA) for surveillance of aortic endografts. Methods: Thirty consecutive patients (29 men; mean age 69 years, range 50–82) who underwent endovascular aortic aneurysm repair agreed to participate in a follow-up program. Patients underwent CTA (26/30) or MRA (4/30), plain abdominal radiography, and unenhanced and enhanced ultrasound examinations at 3, 12, and 24 months to evaluate aneurysm diameter, endoleaks, and graft patency. The accuracy of ultrasound was compared with CTA or MRA as the reference standards. Results: Twenty-six patients reached the 24-month assessment (mean follow-up 30 months, range 6–60). All endoleaks detected by CTA or MRA were confirmed by enhanced ultrasound; the aneurysm diameter in these patients remained unchanged or increased. In patients without endoleaks on any imaging method, the sac diameter remained unchanged or decreased. Endoleaks disclosed by enhanced ultrasound alone, all type II, numbered 16 at 3 months, 6 at 12 months, and 3 at 24 months. In this group, the aneurysm diameter remained unchanged or increased. Enhanced ultrasound yielded 100% sensitivity in detecting endoleaks, but compared with CTA and MRA, all endoleaks detected by enhanced ultrasound alone were false positives (mean specificity 65%). Nevertheless, because changes in the postoperative aneurysm diameter were similar in patients with endoleaks detectable on CTA/MRA and on enhanced ultrasound (“true positives”) and in those with endoleaks detectable only on enhanced ultrasound (“false positives”), some endoleaks were possibly “true positive” results. Conclusions: Enhanced ultrasound is a useful method in the long-term surveillance of endovascular aortic aneurysm repairs, possibly in association with CTA or MRA. Enhanced ultrasound also seems able to identify endoleaks missed by other imaging techniques, but this conclusion awaits further investigation.

Ischemic Nephropathy in an Elderly Nephrologic and Hypertensive Population

Background: Atherosclerotic renovascular disease is a frequent cause of end-stage renal failure leading to dialysis in the elderly population. Its prevalence is known from autopsy or retrospective arteriographic investigations. This prospective study was conducted in 133 subjects with the inclusion criteria of hypertension and/or chronic renal failure starting after 50 years of age. Renal failure was unrelated to other known causes of renal disease. Methods: The patients were subjected to echo-color doppler ultrasonography of renal arteries (104) and/or to renal scintigraphy (112). Thirteen of 27 patients with positivity using one or both noninvasive techniques were subjected to digital selective angiography. Results: All the patients with positivity of echo-color doppler technique were true positives, with a consequent predictive value reaching 100%. Renal scintigraphy was of markedly lower predictive value. Based on the echo-color doppler investigation, percentage positivity for hemodynamically significant stenosis (>50%) was 3.2 (16.3% had mild nonsignificant stenosis of renal arteries) in the 50- to 59-year-old group, 20% (plus 12.5% with nonsignificant stenosis) in the 60- to 69-year-old group and 25% (plus 17.8% nonsignificant stenosis) in the >70-year age group. Patients with significant stenosis also had a significantly higher degree of renal insufficiency and received a higher number of hypotensive drugs (p < 0.013). The percentage of hypertensive patients was not different in the stenotic and nonstenotic groups. Conclusions: A large percentage of the elderly population is affected by renal vascular obstructive disease and is at risk of developing end-stage renal failure. Considering the wide number of cases with foreseeable renal arterial stenosis in the vast population meeting the selection criteria, it is possible to conclude that not all cases evolve to renal failure due to different rates of progression or to untimely nonrenal death.

Imaging of carotid plaque angiogenesis.

Currently, characterization of the vulnerable plaque is a hot research topic as a more adequate strategy for preventing cerebrovascular events is being sought. Histological studies have recognized that plaque inflammation and the presence of adventitial vasa vasorum, intimal angiogenesis and plaque neovascularization are strong predictors of instability in atheromatous lesions of cerebrovascular and cardiovascular patients. The in vivo study of these features has been the focus of development of several new radiological imaging methods. Carotid ultrasound, with ultrasound contrast agents, is not only able to provide an enhanced assessment of the arterial lumen and plaque morphology with an improved resolution of the carotid intima-media thickness, but also to directly visualize adventitial vasa vasorum and plaque neovascularization. This technique and its future clinical implications are discussed in the present review.

Intraoperative Transcranial Doppler Sonography Monitoring during Carotid Surgery under Locoregional Anaesthesia

OBJECTIVES Studies comparing transcranial Doppler ultrasonography (TCD) with other intraoperative monitoring techniques for detecting clamping ischaemia during carotid endarterectomy under general anaesthesia suggest that a reduction of > two-thirds in the mean middle cerebral artery velocity (mMCAv) or a reduction of > 0.4 in the preclamping mMCAv: clamping mMCAv ratio warrants cerebral protection. Our aim was to study the relationship between mMCAvs and clamping ischaemia during carotid endarterectomy in awake patients. MATERIALS AND METHODS In a consecutive series of 57 patients undergoing carotid endarterectomy under locoregional anaesthesia 51 were monitored by intraoperative TCD, continuous EEG, and neurologic awake testing. RESULTS Five of the 51 (9.8%) patients had transient clamping ischaemia, which carotid shunting reversed. TCD showed that these five patients had significant lower mean mMCAvs than the other 46 patients, who had no deficits (1.8 +/- 1.1 cm/s vs. 26.2 +/- 8.5, p = 0.0003). Current TCD criteria indicated that four other patients (7.8%) should have been shunted. All four had significantly higher clamping mMCAvs than the five shunted patients (11.5 +/- 1.9 vs. 1.8 +/- 1.1, p = 0.0012). CONCLUSIONS Intraoperative TCD detected cerebral ischaemia and yielded no false-negative. An mMCAv of 10 cm/s or less may indicate the risk of clamping ischaemia better than the higher threshold currently proposed. This would avoid unnecessary shunting due to false-positives.

Bacterial and clinical criteria relating to the outcome of patients undergoing in situ replacement of infected abdominal aortic grafts

OBJECTIVES In a retrospective non-randomised study we assessed the outcome after in situ replacement of infected knitted Dacron abdominal aortic grafts in patients without septicaemia or retroperitoneal abscesses. We also assessed whether the specific bacterial infection influenced outcome. MATERIALS AND METHODS Over the 5 years studied, 18 patients (9 with perigraft infection and 9 with aortoenteric erosion) underwent in situ replacement of aortofemoral grafts. All patients were haemodynamically stable, none required emergency treatment. Preoperative assessment included CT, MRI, leukocyte-labelled scintigraphy, and bacterial cultures whenever possible. Infected grafts were totally excised and replaced in situ with standard PTFE prostheses. Bacterial diagnosis included intraoperative Gram-staining and postoperative graft cultures. None of the patients had retroperitoneal collections or proximal anastomotic dehiscence. All patients had 6 week intravenous antibiotic therapy. RESULTS One patient died of myocardial infarction, and another of haemorrhagic shock from proximal anastomotic dehiscence, accounting for a graft-related mortality of 6%. Dehiscence resulted from a polymicrobial infection. Mean 37 month surveillance showed no amputations and no graft-related infections. CONCLUSIONS In clinically and bacteriologically selected patients, total in situ replacement of infected abdominal aortic grafts offers an excellent outcome.

Semiquantitative Human Cerebral Perfusion Assessment With Ultrasound in Brain Space-Occupying Lesions Preliminary Data

Objective. Transcranial Duplex ultrasound imaging with ultrasound contrast agents is an emerging technique for evaluating brain perfusion. The aim of this study was to evaluate cerebral perfusion with ultrasound in brain space‐occupying lesions to identify different perfusion patterns. Methods. Twenty patients with brain space‐occupying lesions underwent ultrasound assessment of brain perfusion with a contrast pulse sequencing nonharmonic ultrasound technique and an ultrasound contrast agent bolus. Data were analyzed with software for semiquantitative analysis. Results. Contrast pulse sequencing imaging with the semiquantitative analysis software allowed identification of qualitative and semiquantitative brain perfusion. Brain hemorrhages showed lower or absent perfusion compared with normal tissue. Meningiomas and glioblastomas without large necrotic areas showed higher perfusion compared with normal tissue. Glioblastomas with large necrotic areas showed overall reduced perfusion compared with normal tissue but higher than that of brain hemorrhages. In glioblastomas with large necrotic areas, it was possible to distinguish between solid and necrotic tissue. Conclusions. This bedside ultrasound technique, if validated by larger‐scale studies, may add helpful information in noninvasive staging of brain tumors. Further potential applications may be in follow‐up imaging to evaluate postoperative tumor recurrence or the presence of radionecrosis.

Minor asymptomatic carotid stenosis contralateral to carotid endarterectomy (CEA): Our experience

The authors report their experience from 1985 to 1988 with 75 consecutive patients affected by bilateral carotid artery stenosis in whom only one side was surgically treated and the other had a minor (15-45%) asymptomatic carotid stenosis. These patients have been followed for a period ranging from 10 to 50 months (mean follow-up 21 months) by clinical examinations and non-invasive investigations (Doppler CW, Duplex scanner). The non-invasive evaluation included assessment of haemodynamic data and characterisation of plaque morphology (regular vs. irregular or ulcerated surface, homogeneous vs. heterogeneous plaque). During follow-up eight patients died: two (2.6%) from acute myocardial infarction, four from stroke (5.3%), and two (2.6%) from other causes. Twenty-five patients (33.3%) had neurological symptoms related to the unoperated side: and four suffered stroke (5.3%). Twenty-one patients had TIAs (28%) related to the observed side. During follow-up five out of 29 (17.2%) homogeneous and 20 out of 46 (43.4%) heterogeneous plaques progressed (p less than 0.01). With regard to the surface characteristics, nine out of 25 regular plaques progressed and only three patients (12%) had neurological events; 19 out of 34 (55.9%) irregular plaques showed a progression and 14 caused neurological symptoms. Fourteen ulcerated plaques (87.5%) progressed (p less than 0.01). Our experience suggests that the basic trend in the follow-up of patients with bilateral carotid artery disease, is that the contralateral unoperated lesion may evolve and become symptomatic. These symptoms are generally TIAs but five patients (4.3%) suffered from strokes related to the unoperated side, all without warning TIAs.