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R G A Ackerstaff

Publications and source records attributed to R G A Ackerstaff.

16 recordsLinked to original sources
PubMed2006

Intrapatient comparison of restenosis between carotid artery angioplasty with stenting and carotid endarterectomy.

AIM: Comparison of restenosis in patients who underwent both carotid artery angioplasty with stenting (CAS) and contralateral carotid endarterectomy (CEA). METHODS: From our CAS data registry (1998-present) all patients with a history of contralateral CEA at any other time were selected (n = 63). Mean age was 70.6, SD = 6.8 for CAS and 68.2, SD = 6.1 for CEA and symptomatic carotid artery stenosis was present in 24% of patients pre-CAS and 40% pre-CEA. All CEAs were primary interventions, 19% of CAS were secondary to restenosis after previous ipsilateral CEA. All patients were followed up prospectively with duplex at 1 year (CAS: n = 58, CEA: n = 59), 2 years (CAS: n = 44, CEA: n = 53), 3 years (CAS: n = 27, CEA: n = 41), and every year thereafter. Within each patient we compared restenosis (>50%) between CAS and CEA procedures. RESULTS: After a follow-up of 28.7 months for CAS (SD = 16.9) and 54.4 months for CEA (SD = 39.5) the rate of = or > 50% restenosis for CAS vs CEA at 1, 2, and 3 years was 23% vs 10%; 31% vs 19%; and 34 vs 24%, respectively (log rank P = NS). CONCLUSIONS: Our intrapatient comparison of patients who underwent both CAS and contralateral CEA did not reveal significant difference in restenosis between both procedures.

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PubMed2006

The carotid atherosclerotic plaque and microembolisation during carotid stenting.

Microembolisation is an important issue in carotid artery stenting. During different phases in the stenting process, numerous emboli are dislodged from the atherosclerotic plaque. Embolisation can be measured as microembolic signals detected by transcranial Doppler (TCD) monitoring during the procedure or as new ischemic areas determined by magnetic resonance imaging. This article gives an overview of the principles of emboli detection methods, their clinical relevance, and risk factors associated with microembolisation. In addition, protection devices are discussed in relation to embolisation. Although they potentially protect the brain, particularly filter devices increase the amount of TCD-detected cerebral microemboli. Special attention is paid to the carotid artery plaque, which is subject to ongoing research that may yield important implications for clinical practice in the near future. Evidence is accumulating that unstable, vulnerable plaques are associated with increased microembolisation during carotid interventions. This knowledge of the vulnerable plaque can be translated to the clinical setting by plaque imaging. A first approach has been made by duplex imaging of carotid plaque morphology. More advanced methods such as molecular magnetic resonance imaging and optical coherence tomography could aid in optimal treatment selection based on plaque characteristics thus reducing microembolisation and associated cerebral adverse events.

Angioplasty↗
PubMed2005

Carotid atherosclerotic plaque characteristics are associated with microembolization during carotid endarterectomy and procedural outcome.

BACKGROUND AND PURPOSE: During carotid endarterectomy (CEA), microemboli may occur, resulting in perioperative adverse cerebral events. The objective of the present study was to investigate the relation between atherosclerotic plaque characteristics and the occurrence of microemboli or adverse events during CEA. METHODS: Patients (n=200, 205 procedures) eligible for CEA were monitored by perioperative transcranial Doppler. The following phases were discriminated during CEA: dissection, shunting, release of the clamp, and wound closure. Each carotid plaque was stained for collagen, macrophages, smooth muscle cells, hematoxylin, and elastin. Semiquantitative analyses were performed on all stainings. Plaques were categorized into 3 groups based on overall appearance (fibrous, fibroatheromatous, or atheromatous). RESULTS: Fibrous plaques were associated with the occurrence of more microemboli during clamp release and wound closure compared with atheromatous plaques (P=0.04 and P=0.02, respectively). Transient ischemic attacks and minor stroke occurred in 5 of 205 (2.4%) and 6 of 205 (2.9%) patients, respectively. Adverse cerebral outcome was significantly related to the number of microembolic events during dissection (P=0.003) but not during shunting, clamp release, or wound closure. More cerebrovascular adverse events occurred in patients with atheromatous plaques (7/69) compared with patients with fibrous or fibroatheromatous plaques (4/138) (P=0.04). CONCLUSIONS: Intraoperatively, a higher number of microemboli were associated with the presence of a fibrous but not an atheromatous plaque. However, atheromatous plaques were more prevalent in patients with subsequent immediate adverse events. In addition, specifically the number of microemboli detected during the dissection phase were related to immediate adverse events.

Adult↗
PubMed2005

The depth of microembolic signal direction change corresponds with vessel anatomy.

BACKGROUND: Analysis of microembolic signals (MES) suggests a change of flow direction (CFD). The aim of the present study was to relate MES direction in an amplitude plot, based on the radiofrequent (RF) signal, to the vascular anatomy as seen with transcranial color-coded duplex (TCCD). METHODS: In 5 patients undergoing heart valve surgery or aortic arch replacement, preoperatively TCCD of the distal part of the internal carotid artery and the middle and anterior cerebral arteries on the right side was performed to determine potential depths of changes in flow direction. Peroperatively, a transcranial pulsed Doppler (TCD) monitoring probe was fixed over the right temporal bone. A customized RF-based system, connected to the TCD device, captured and stored the MES. Off-line, the color-coded amplitude of the clutter-filtered RF signals was plotted as a function of time (sample interval 0.17 ms) and depth (sample interval 0.05 mm). RESULTS: A total of 313 MES were recorded in 4 patients with 66 MES (21%) showing a CFD. All MES with CFD could be assigned to maximally three different depth values, six out of eight CFD depth values as seen with the RF analysis were within 1 mm from a turn in flow direction as estimated with TCCD. CONCLUSIONS: A CFD of MES occurred at a very limited number of depths and corresponded mostly with the intracranial vascular anatomy, namely a turn of the flow direction in the intracranial vessels as observed with TCCD.

Carotid Artery, Internal↗
PubMed2005

Transcranial Doppler monitoring after carotid endarterectomy.

The objectives of this study were to evaluate the feasibility of transcranial Doppler (TCD) monitoring after carotid endarterectomy (CEA) and to investigate whether 1 hr of monitoring is sufficient to detect a clinically relevant change in the number of postoperative microemboli. We also evaluated the association of patient characteristics and procedure-related variables with the number of postoperative microemboli. One hundred and two patients were monitored during the second hour after CEA. The main outcome measure was the number of TCD-detected microemboli. The secondary outcome measure was a procedure-related cerebral complication graded according to the modified Rankin scale. The median number of microemboli during the second postoperative hour was two (interquartile ranges, 0.75-11) and decreased in most the patients during this time. Two patients had a relatively high and increasing number of microemboli and developed a minor stroke after a symptom-free interval. One patient developed a TIA intraoperatively. There was no significant association between patient characteristics and the use of a venous patch and the number of postoperative microemboli. Conversely, a statistically significant negative association was found between shunt use and the number of microemboli (p = 0.02). The majority of patients had no or a small and decreasing number of microemboli. One hour of monitoring appeared to be effective to select those patients in whom the number of microemboli did not spontaneously decrease and who may need additional medical treatment or surgical reexploration. The role of TCD-detected microemboli as a surrogate measure for the risk of stroke after CEA remains to be validated.

Aged↗
PubMed2005

Perioperative microembolism is not associated with cognitive outcome three months after carotid endarterectomy.

OBJECTIVE: To investigate the association between perioperative microembolism and cognitive outcome 3 months after carotid endarterectomy (CEA). DESIGN: Prospective study. MATERIALS AND METHODS: Patients were tested 1 day before and 3 months after surgery with neuropsychological tests measuring a wide range of cognitive functions. Number of microemboli was monitored with transcranial Doppler ultrasonography in 58 patients during the operation and in a random subgroup of 27 patients directly following the procedure. RESULTS: Forty patients (69%) had intraoperative embolism, varying from 1 to 33 isolated microemboli and/or 1 to 11 embolic showers. Postoperative emboli were present in 22 of the 27 patients (81%), ranging from 1 to 142 isolated microemboli. More than 10 microemboli (including showers) were detected in 13 patients (22%) intraoperatively and in 6 patients (22%) postoperatively. Twenty-two patients (38%) showed deterioration in three or more cognitive function variables at 3 months. There were no significant associations between any cognitive change or deterioration score and presence or number of intraoperative and/or postoperative emboli. CONCLUSIONS: The degree of microembolism during and immediately following CEA is generally small and seems to be of no significance with respect to postoperative cognitive functioning. Future research should include a larger group of patients to allow reliable subgroup analysis.

Aged↗
PubMed2005

Identification of patients at risk for ischaemic cerebral complications after carotid endarterectomy with TCD monitoring.

OBJECTIVES: Transcranial Doppler (TCD) monitoring for micro embolic signals (MES), directly after carotid endarterectomy (CEA) may identify patients at risk of developing ischaemic complications. In this retrospective multicentre study, this hypothesis was investigated. METHODS: Centres that monitored for MES after CEA were identified by searching Medline. Individual patient data were obtained from centres willing to collaborate. The number of emboli in 1h was computed. Uni- and multivariate logistic regression analyses were performed for the variables gender, age and number of MES. Discriminative ability of MES monitoring was investigated in a ROC curve. RESULTS: Nine hundred and ninety-one patients were monitored in the first 3h after CEA. Two percent developed ischaemic cerebral complications. Univariate analysis revealed statistically significant associations between ischaemic cerebral complications and both gender and MES, but not age. In a multivariate analysis, > or =8 MES/h showed a statistically significant relationship with cerebral complications (OR 8.1, 95% CI 1.8-36), in contrast to gender (OR 2.2, 95% CI 0.9-5.5). The ROC curve yielded an AUC of 0.83 for monitoring of MES. CONCLUSIONS: These results support the use of TCD monitoring for MES shortly after CEA in order to identify patients at risk of developing ischaemic cerebral complications.

Aged↗
PubMed2004

Postoperative changes in duplex ultrasound velocity characteristics in the nonmobilized right internal mammary artery in patients with left internal mammary artery bypass grafting.

The internal mammary artery (IMA) is the conduit of choice in coronary revascularization because of its long-term patency. We analyzed the effect of left internal mammary artery (LIMA) harvesting on sternal perfusion. Diameters and velocity parameters of the nonmobilized right internal mammary artery (RIMA) were noninvasively analyzed with duplex ultrasound in 41 patients with LIMA myocardial revascularization pre- (2.6 +/- 5 days) and postoperatively (4.9 +/- 3.9 months). Data of 41 patients were analyzed; 38 patients underwent all examinations with adequate supraclavicular signals. The proximal RIMA diameter and all velocity parameters increased significantly at follow-up (3.1 +/- 0.6 vs. 3.2 +/- 0.5 mm, p = 0.03; diastolic peak velocity [DPV] 15 +/- 7 vs. 27 +/- 9 cm/sec, p < 0.0001; systolic peak velocity [SPV] 90 +/- 24 vs. 105 +/- 29 cm/sec, p < 0.02). This was more pronounced for the diastolic parameters and for all parameters in the proximal part of the RIMA than in the distal part (DPV 11.9 +/- 10.1 vs. 9.5 +/- 10.2 cm/sec, p = NS; SPV 14.9 +/- 33.9 vs. 7.4 +/- 26.0 cm/sec, p = NS). With longer time intervals of follow-up the increase in all diastolic velocity parameters became less pronounced. As demonstrated in the RIMA velocity parameters, patients with skeletonized LIMA grafts (n = 4) had significantly more flow, suggesting hyperemic flow, than patients with pedicled LIMA grafts (n = 34). Only in diastolic velocity integral (DVI) and systolic/diastolic velocity ratio (SDVRA) were there significant differences between diabetics (n = 9) and nondiabetics (n = 29) and only in DVI between female, (n = 8) and male (n = 30) patients. This study indicates that duplex ultrasound is a useful tool for noninvasive RIMA follow-up in LIMA myocardial revascularization.

Aged↗
PubMed2004

Left or right carotid endarterectomy in patients with atherosclerotic disease: ipsilateral effects on cognition?

We evaluated hemispheric functions ipsilateral to the side of carotid endarterectomy (CEA) in patients with a severe stenosis in the left or right carotid artery. Assessments took place 1 day before and 3 months after CEA. Only right-handed males were included. Nineteen patients underwent surgery of the left carotid artery and 17 of the right. Valid instruments for hemispheric function were included, such as verbal dichotic listening, finger tapping, and a lateralised test for motor planning. Results showed that, preoperatively, patients had lower scores compared to norms on the laterality tests, and on a visuoconstructive test. There was no evidence of ipsilateral improvement related to side of surgery. Left ear dichotic listening improved, which was seen in both left and right surgery groups. Also in both groups, left- and right-hand movement speed in the motor planning test decreased. Conclusion is that beneficial ipsilateral cognitive change after CEA in patients with severe stenosis in one of the carotid arteries may not be demonstrated, even if valid instruments for hemispheric function are included.

Aged↗
PubMed2004

TCD-detected cerebral embolism in carotid endarterectomy versus angioplasty and stenting of the carotid bifurcation.

PURPOSE: In this article we will review some of the issues surrounding the relationship between TCD-detected emboli and brain function and architecture, both during conventional surgical carotid endarterectomy (CEA) and carotid angioplasty and stenting (CAS). MATERIAL AND METHODS: In both procedures, the cerebral embolic load was semi quantitatively assessed and associated with clinical outcome during the procedure and after a symptom free interval within 7 days. RESULTS: In CEA, particulate emboli that occurred during the wound closure stage were associated with intraoperative stroke and stroke related death, odds ratios [OR] 2.3 95% CI 1.2-4.4, p = 0.007. In CAS, showers of microemboli that appeared at postdilatation of the stent (OR 3.2, 95% CI 1.5-6.9, p = 0.002), particulate macroembolism (relative risk [RR] 10.2, 95% CI 5.9-17.3, p < 0.001), and massive air embolism (RR 10.2, 95%CI 5.8-17.7, p < 0.001) were associated with new transient and persistent cerebral deficits. CONCLUSION: In both CEA and CAS, recording of cerebral emboli by TCD ultrasonography provides insight in the pathogenesis of procedure related adverse cerebral outcome. In several centres TCD monitoring during CEA is now accepted as a clinically relevant tool that helps the surgeon to make the operation safer. In CAS more research is needed, particularly with respect to the impact of cerebral protection devices.

Aged↗
PubMed2003

Feasibility and reliability of on-line automated microemboli detection after carotid endarterectomy. A transcranial Doppler study.

OBJECTIVES: recently, a new algorithm for transcranial Doppler (TCD) ultrasound detection of microembolic signals (MES) was developed. In the present study, we investigated its on-line performance in TCD monitoring after carotid endarterectomy (CEA) and assessed off-line its accuracy in detecting MES. MATERIALS AND METHODS: first, the feasibility of MES detection in TCD monitoring after CEA in a routine clinical setting was evaluated in 50 patients. Second, to test the reliability of the software a 2-h digital audio study tape was made and analysed by the algorithm and five human experts. The "gold standard" was defined as the agreement between human experts: a MES was considered to be present if at least three human observers agreed. RESULTS: TCD monitoring for emboli detection after CEA was well tolerated by the patients and could be performed reliably. In the study tape, the human gold standard detected 107 MES, with 93 MES having an intensity of > or =7 dB. The software detected 81 and 77 MES, respectively. Using the 7 dB intensity threshold, the software had no false positives and 16 false negatives. The kappa value between the human gold standard and the software was 0.91, the proportion of specific agreement was 0.83. CONCLUSIONS: the tested algorithm provides a reliable method for automated on-line microemboli detection after CEA. This makes monitoring of the effectiveness of antiplatelet agents in the prevention of stroke after CEA more practicable.

Algorithms↗
PubMed2003

Operative management of carotid artery in-stent restenosis: first experiences and duplex follow-up.

OBJECTIVES: Carotid Artery Stenting (CAS) may be comparable to Carotid Endarterectomy (CEA) as a durable and effective procedure in stroke prevention. Concern remains about the incidence of restenosis after stenting and its management. We evaluated the surgical management of restenosis after CAS. DESIGN: prospective study. METHODS: between December 1997 and April 2001, 217 CAS procedures were performed in 217 patients (155 men and 62 women; age 70 years +/- 8.2). After a mean of 8 months post-stenting four patients (two symptomatic, two asymptomatic with contralateral occlusion) with severe haemodynamic in-stent restenosis (90-99%) had surgical reintervention. RESULTS: standard CEA with removal of the stent was performed in all four patients. No major complications occurred. Intima hyperplasia showed to be the predominant mechanism leading to in-stent restenosis. All four surgically treated patients remained asymptomatic and without recurrent restenosis over a mean follow-up time of 13 months (range 3-20 months). CONCLUSION: the optimal treatment of in-stent restenosis has yet to be defined, but standard CEA with removement of the stent appears to be feasible.

Aged↗
PubMed2003

Restenosis after carotid angioplasty and stenting: a follow-up study with duplex ultrasonography.

OBJECTIVES: To prospectively document the incidence, location, risk factors for and clinical consequences of restenosis after carotid artery angioplasty and stenting (CAS). METHODS: Serial duplex and neurological examinations were performed in 217 patients one day (n = 216), 3 (n = 189), 12 (n = 129) and 24 (n = 48) months, after CAS. The relationship between patient, lesion and procedure variables and restenosis was determined at 12 months. RESULTS: The prevalence of restenosis > or = 50% was 14, 16, 18, and 21%, respectively, and was only significantly related with loss of proximal stent apposition (odds ratio 3.4, 95% confidence interval: 1.0-11.7, p < 0.05). Four restenoses were symptomatic. CONCLUSIONS: Restenosis after CAS is common, unpredictable but infrequently symptomatic.

Aged↗
PubMedDate not supplied

Microembolic signal description: a reappraisal based on a customized digital postprocessing system.

The high variability in presence and signature of microembolic signals (MES), detected with transcranial Doppler sonography (TCD) in the middle cerebral artery (MCA), cannot be explained with the currently available published data. We applied customized postprocessing on the radiofrequency (RF) signal of a standard TCD system. The spatial resolution was on the order of 2 mm, depending only on the length of the ultrasound (US) burst emitted. The amplitude of clutter-filtered RF signals was color-coded and plotted as a function of time and depth (range 30 mm). Additionally, 128 point fast Fourier transforms (FFTs) (50% temporal overlap) were calculated, visualizing both the background Doppler spectrum and the MES. We evaluated 122 gaseous MES from two patients during cardiac surgery and 52 particulate MES from four patients after carotid endarterectomy. Both MES categories showed comparable properties: they appeared in the RF amplitude plot as rather straight lines of increased intensity, indicating that the velocity remained approximately the same while they passed the US beam. The velocity calculated from the amplitude plot never exceeded that of the background Doppler spectrum. Various "MES patterns" could be identified with respect to the depth range at which the MES were visible. A quarter of the gaseous MES changed their direction at a specific depth, suggesting that the MES entered a branch (e.g., an M2 artery or the anterior cerebral artery). In the FFT analysis, these MES contained both positive and negative frequencies. It is concluded that MES show consistent signature patterns in the amplitude-time plots and that the previously reported variability of MES appearance in conventional Doppler systems is an artefact caused by relatively large signal amplitudes and sample volumes.

Artifacts↗
PubMedDate not supplied

Carotid endarterectomy in octogenarians with symptomatic high-grade internal carotid artery stenosis: long-term clinical and duplex follow-up.

The objective of this study was to evaluate the clinical and duplex outcome after carotid endarterectomy (CEA) in recently symptomatic patients aged 80 years or older. Information was assembled from a prospective data collection of all CEAs performed from January 1986 to December 1999. Included were all patients with recently symptomatic carotid artery stenosis who were aged 80 years or older at time of operation. Thirty-two patients, with a mean age of 82 years, were included. Outcome events were stroke, death, and restenosis (more than 50% diameter reduction) during routine duplex scan follow-up. Conventional surgical technique was used regarding anesthesia and selective shunting or patching. None of the operated-on patients suffered a stroke at any time during follow-up. One patient (3.1%) died in the early postoperative phase (<30 days). An additional 8 patients died during follow-up. None of these deaths were of cerebrovascular origin. Survival at 3 years was 73% (life table analysis). Routine duplex scan follow-up showed 2 patients with a diameter reduction of more than 50%, both 3 months after CEA. Restenosis rate on duplex scan was 7.4% after 1 year. The authors conclude that there seems to be no reason to deny the very elderly the benefits of CEA. Stroke-free survival and survival rates show that carotid surgery is a safe procedure in patients aged 80 and over who are in apparently good health. These findings are supported by a low incidence of restenosis on duplex scan follow-up, indicating a durable repair.

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