Use of Doppler ultrasound in the management of uteroplacental perfusion during cardiopulmonary bypass in pregnancy.

Cardiopulmonary bypass, the extreme of non-obstetric surgery during pregnancy, presents unique challenges to minimize maternal and fetal risk. We present our experience with a woman who was diagnosed with a left atrial myxoma following an ischemic cerebrovascular accident. We discuss clinical management specific to cardiopulmonary bypass during pregnancy and delivery in the context of a multidisciplinary team approach. We recommend using intermittent Doppler ultrasound as a non-invasive real-time assessment of uteroplacental perfusion during non-obstetric surgery in pregnancy. Monitoring of perfusion facilitates active feedback for appropriate in utero resuscitation in these cases.

Carotid interventions (CEA and CAS) in acute stroke patients: which procedure on which patient.

Treatment of carotid bifurcation disease in patients presenting with acute stroke has been a controversial issue over the past four decades. Classically, patients were asked to wait four to six weeks before intervention was entertained in order for the brain to stabilize and the risks of intervention to be minimized. Unfortunately, up to 20% of patients will have a secondary event after their index event and the window of opportunity to save, potentially salvageable ischemic tissue will be missed. Early reports had demonstrated poor results with intervention. However, more recently, institutions such as ours have demonstrated excellent result in early intervention in patients who present with stable mild to moderate stroke with an NIH stroke scale less than 15 and preferably less than 10, present with stroke and ipsilateral carotid artery lesion of 50% or greater. Also more recently, we have been aggressively treating patients with larger ulcerative plaques even if the stenosis approaches 50%. In our and others experiences, patients who are treated at institutions that have comprehensive stroke centers (CSCs) where they have a multidisciplinary system that consists of vascular surgeons, neuro interventionalists, stroke neurologists, specifically trained stroke nursing staff and a neuro intensive ICU have had optimal results. Early assessment, diagnosis of stroke with recognition of cause of embolization is mandatory but patient selection is extremely important; finding those patients who will benefit the most from urgent intervention. Most studies have demonstrated the benefit of carotid endarterectomy in these patients. More recent studies have demonstrated acceptable results with carotid stenting, especially in smaller lesions, those less than 1.2 centimeters. Early intervention should be avoided in most patients who are obtunded or with an NIH stroke scale greater than 15 or who do not have any "brain at risk" to salvage. These patients may be better served by being treated medically than those small group of patients that do have some improvement may benefit from interval intervention.

Neurological disorders in HIV-infected children in India.

UNLABELLED: There are few studies of HIV-related neurological disorders from centres in low-income countries where facilities are available for detailed investigation. METHODS: Records of all patients attending the paediatric HIV outpatient department at B. J. Wadia Hospital for Children, Mumbai between April 2000 and March 2008 were reviewed. Of 668 HIV-infected patients, 48 (7.2%) had neurological manifestations and are included in this study. RESULTS: Twenty-six (54.2%) children had HIV encephalopathy. Other causes of neurological manifestations include febrile convulsion in five (10.4%), bacterial meningitis in three (6.3%), epilepsy in two (4.2%), tuberculous meningitis and progressive multi-focal encephalopathy in two (4.2%) each and toxoplasmosis, vasculitis, acute demyelinating encephalomyelitis, anti-phospholipid antibody syndrome, Down's syndrome, birth asphyxia, herpes simplex encephalopathy and mitochondrial encephalopathy in one (2.1%) each. Mean (SD) age at presentation was 4.36 (3.38) years with a range of 2 months to 15 years. The common subtle neurological manifestations were abnormal deep tendon reflexes and extensor plantar reflexes. The common symptomatic manifestations were delayed milestones in 21 children (43.8%) and seizures in 19 (39.6%). Seizures were more common in males (54%) than in females (25%) (p=0.038). In children <5 years, delayed milestones was the most common manifestation while focal neurological deficits were more common in older children. Of the 13 children who received HAART, nine (60.23%) improved. CONCLUSION: Early diagnosis of neurological disorders in HIV-infected children is important for appropriate investigation and management, especially the introduction of HAART.

Long term outcome for extra-anatomic arch reconstruction. An analysis of 143 procedures.

PURPOSE: With the FDA approval of thoracic endografts, extra-anatomic reconstruction of the aortic arch has allowed for more suitable proximal landing zones and increased applicability of thoracic endovascular procedures. We evaluated our short term and long term results of extra-anatomic reconstruction of the carotid and subclavian vessels. METHODS: One hundred and forty three (143) procedures were performed for extra-anatomic carotid and subclavian reconstruction. Of these 143 operations: 85 were carotid subclavian reconstructions, 22 were carotid crossover bypasses, 30 were subclavian carotid reconstructions and 6 were carotid subclavian transpositions. Sixty (42%) were male, 20 (14%) were diabetic, and 63 (44%) were current smokers. Mean age was 63 (SD +/- 12.3). Indication for surgery was primarily for occlusive or embolic disease (97%). In those patients undergoing bypass graft, prosthetic (ePTFE) was used in 93%. Follow-up was performed at 3 and 6 month intervals by ultrasound and pulse volume recordings where indicated. Life table analyses were used to analyze patency. RESULTS: Of the 143 reconstructions operative mortality was 1 (0.7%). Non-fatal complications included 3 (2.1%) for bleeding, 1 (0.7%) wound infection, 2 (1.4%) TIA, 1 (0.7%) suffered a non-fatal stroke, 2 (1.4%) had postoperative myocardial infarctions, and 6 (4.3%) late (>30-day) occlusions. Follow-up was 1 to 124 months (mean: 39 months). Primary patency at 1 year was 98%, 3 years 96%, and 5 years was 92%. CONCLUSION: Extra-anatomic arch reconstruction can be performed safely and appears to be durable over long term follow-up. Its use with endovascular grafting should provide a durable reconstruction for patients who require aortic "debranching" prior endovascular thoracic aortic aneurysm repair.

Relationship of proximal fixation to renal dysfunction in patients undergoing endovascular aneurysm repair.

Technological advancements have lead to dramatic improvements in stentgraft device design resulting in more trackable delivery systems and transrenal uncovered stents and barbs for better fixation. Transrenal bare-stents may limit stentgraft migration, particularly in patients with short or flared proximal aortic necks. However, potential disadvantages might be in worsening renal function, particularly in patients with preexisting renal insufficiency. We retrospectively analyzed our recent 7 year experience of patients undergoing endovascular aneurysm repair (EVAR) using a variety of stentgrafts with and without transrenal bare-stent fixation. Patients were divided into 2 groups; infrarenal fixation (IRF) vs transrenal fixation (TRF), or patients with preoperative serum Cr values that were normal (= or <1.5 mg/dl) vs slightly elevated (1.6-2 mg/dl), vs markedly elevated (2.1- 3.5 mg/dl). The exclusion criteria included patients with chronic renal insufficiency (CRI) on hemodialysis, and preoperative high-grade renal artery stenoses requiring angioplasty and stenting. Of 705 patients that underwent EVAR, 496 (IRF: 385 [78%], and TRF: 111 [22%]) were available with routine evaluations of serum Cr and CT scans. Preexisting comorbidities, mean procedure contrast volume, and postprocedure follow-up were similar in both groups. In the immediate postoperative period, mean serum Cr did not change significantly in either the IRF group (1.3+/-0.7 mg/dl to 1.2+/-0.9 mg/dl) or the TRF group (1.3+/-0.5 mg/dl to 1.3+/-0.6 mg/dl). Mean serum Cr did, however, significantly increase over longer follow-up in both groups: 1.4+/-0.8 mg/dl for IRF (P<0.03), and 1.5 +/- 0.8 mg/dl for TRF (P<0.01). Cr clearance was similarly unchanged in the immediate postoperative period (58+/-23 to 61+/-25 ml/min/1.73 m2 for IRF group, 53+/-17 to 55+/-17 ml/min/1.73 m2 for TRF group), but was significantly decreased in longer follow-up (53+/-23 ml/min/1.73 m2 for IRF, p<0.02: and 48+/-16 ml/min/1.73 m2 for TRF, P<0.01). There were no significant differences in serum Cr increase (p=0.19) or Cr clearance decrease (p=0.68) between the IRF and TRF groups. Small renal infarcts were noted in 6 patients (1.6%) in the IRF group, and in 8 patients (7%) in the TRF group (p=0.37). Of patients with normal preoperative renal function, renal dysfunction developed in 7.7% of IRF group and 6.1% of TRF group (p=0.76). In patients with preexisting CRI, renal dysfunction developed in 18.2% of IRF group, and 17.1% of TRF group (p=0.95). Eight patients with postoperative renal dysfunction, 5 (1.3%) from IRF group and 3 (2.7%) from TRF group subsequently required hemodialysis, and this difference was not statistically significant (p=0.91). We also analyzed 200 consecutive patients undergoing EVAR with intra-arterial contrast agents with and without preexisting CRI not on dialysis. The groups were identified on the basis of preprocedure serum Cr: group 1 (n=108), Cr less than 1.5 mg/dL (normal range); group 2 (n=65), Cr 1.5 to 2.0 mg/dL; group 3 (n=27), Cr 2.1 to 3.5 mg/dL. Routine precautions in patients with CRI included preoperative intravenous hydration with 2 L of normal saline solution, discontinuation of all nephrotoxic drugs, intraoperative administration of mannitol (0.5 g/kg intravenously), and use of nonionic, low osmolar intra-arterial contrast agent (Omnipaque 350). One-hundred and eight patients had normal renal function (group 1), and 92 patients had preexisting CRI with baseline Cr 1.5 to 2.0 mg/dL (group 2, n=65) or 2.1 to 3.5 mg/dL (group 3, n=27). Comorbid conditions included coronary artery disease (group 1, 51%; group 2, 49%; group 3, 59%), hypertension (group 1, 39%; group 2, 46%; group 3, 52%), and diabetes mellitus (group 1, 25%; group 2, 35%; group 3, 48%). In groups 1, 2, and 3, the mean volume of low osmolar contrast agent used was 210 cc, 160 cc, 130 cc, respectively; hemodynamic instability developed in 3, 1, and 1 patient, respectively. The incidence of postoperative complications between the 3 study groups was not statistically different. In grications between the 3 study groups was not statistically different. In group 1 a transient increase in serum Cr (>30% over baseline and >1.4 mg/dL) was noted in 3 patients (2.7%), 2 of whom (1.9%) required temporary hemodialysis and 1 (0.9%) who died of renal failure. In group 2 a transient increase in serum Cr was noted in 2 patients (3.1%); both patients (3.1%) required temporary hemodialysis, and 1 patient (1.5%) died of renal failure. In group 3 a transient increase in serum Cr was noted in 2 patients (7.4%); 1 patient (3.7%) required temporary hemodialysis, and 1 patient (3.7%) died of renal failure. Perioperative hypotension significantly increased the risk for elevated serum Cr and death (p<0.05), and larger contrast volume was associated with an increase in serum Cr (p<0.05) during the postoperative period. Following EVAR renal function declines slightly with both IRF and TRF. Our data show no overall difference between patients with IRF and TRF with respect to infarcts, decline in renal function, or onset of dialysis. There were a slightly greater number of renal infarcts in the TRF group, but these infarcts were clinically inconsequential. In patients with CRI, EVAR with intra-arterial radiographic contrast agents is believed to impair renal function, and CRI is considered a relative contraindication to the procedure. Results of our investigation indicate that risk for worsening renal insufficiency, dialysis, and death is only slightly and not significantly greater in patients with CRI compared with patients with normal renal function. With appropriate precautions of avoiding perioperative hypotension and limiting the volume of nonionic contrast agents, CRI need not be a contraindication for EVAR with intra-arterial contrast agents.

Is prosthetic renal artery reconstruction a durable procedure? An analysis of 489 bypass grafts.

OBJECTIVE: Renal artery stenosis has been classically addressed with saphenous vein bypass graft or transaortic endarterectomy performed either primarily or in combination with an aortic procedure. In this series, we report the outcome of our 12-year experience with renal artery reconstruction using prosthetic conduit. METHODS: Patients undergoing renal artery bypass grafting from 1987 to 1999 were identified. Demographics, indications, concurrent operations, complications, and patency were analyzed. Patients underwent postoperative duplex scan with subsequent ultrasound scans at 6-month intervals. RESULTS: There were 489 procedures performed in 414 patients with indications: high-grade renal artery stenosis in combination with abdominal aortic aneurysm repair or symptomatic aortoiliac occlusive disease (309 [63%]), renovascular hypertension (118 [24%]), and renal salvage (20 [4%]). Indications for the remainder included trauma, renal artery aneurysm, or an infected aortic graft. Inflow was aorta or aortic graft in 95% of patients with the remainder taken from the iliac or visceral vessels. The retroperitoneal approach was used in 97.8%. Nonfatal complications occurred in 11.4% with a 1.4% early and 4.8% late occlusion rate. Renal function worsened in 3.1% of all patients. Secondary patency at 1 and 5 years was 98% and 96%, respectively. CONCLUSION: Renal artery reconstruction with prosthetic conduit has an acceptable and durable result whether used for primary renal artery reconstruction or concomitant reconstruction with aortic procedures.

Perinatal implications of maternal hypertension.

Hypertensive disorders of pregnancy are prototypical of maternal conditions associated with reduced uteroplacental blood flow. Hypertensive disorders in pregnancy include chronic hypertension, preeclampsia-eclampsia, superimposed preeclampsia, and gestational hypertension. Pathophysiology of these disorders include deficient uterine vascular modeling in the process of placentation and aberrations of vasomotor regulation. Aberrations of uterine renin-angiotensin system may play a proximate role in the pathogenesis of preeclampsia syndrome. Clinical manifestations are explained in this review based on resultant vasoconstriction and ischemia in systemic and regional circulations. Perinatal implications of hypertensive disorders both in terms of early neonatal outcome and long-term neurodevelopmental effects are described. Methods of antenatal assessment of the fetus and, briefly, principles of clinical management are described.

Brachial artery reconstruction for occlusive disease: a 12-year experience.

OBJECTIVE: Symptomatic arterial disease of the upper extremity is an uncommon problem. In this study, we evaluate our results with brachial artery reconstruction in patients who present with symptomatic atherosclerotic occlusive disease and compare this cohort's demographics with a similar group with lower extremity ischemia. METHODS: From 1986 to 1998, all patients presenting for upper extremity revascularization with chronic ischemia were prospectively entered into a vascular registry. Demographics, indications, outcomes, and patency were recorded. Patients presenting with embolus, pseudoaneurysm, or trauma were excluded. The Fisher exact and Student t tests were used to assess significance. RESULTS: Fifty-one (83%) bypass grafts were performed with autogenous conduit and the remainder with polytetrafluoroethylene. Indications included 18 (30%) patients with exertional arm pain, 35 (57%) with rest pain, and 8 (13%) with tissue loss. Twenty-five (45%) patients were male, 8 (14%) had diabetes, and 30 (54%) were smokers. The mean age was 58 years (range, 33-93). The operative mortality rate was 1.8%, and follow-up ranged from 1 to 140 months. Eight occlusions were identified, with six occurring early. Five of these were in women with a smoking history. Only one of the 26 reconstructions that did not cross a joint occluded, whereas bypass grafts that did cross a joint occluded more frequently. No other major complications were recognized. CONCLUSION: Arm revascularization for ischemia can be performed with reasonable mortality and morbidity rates. These patients may represent a different subgroup of atherosclerotic disease than those with lower extremity involvement: they are more commonly women and smokers and less likely to be diabetic.

Coronary artery bypass combined with bilateral carotid endarterectomy.

BACKGROUND: Surgical management of patients presenting for coronary artery bypass grafting with significant bilateral carotid artery stenosis has not been well defined. In this study, our preliminary results of coronary artery bypass grafting with concomitant bilateral carotid endarterectomy have been reviewed. METHODS: A retrospective nonrandomized chart review was performed in 33 patients with unstable angina and bilateral carotid artery stenosis, more than 70%, undergoing simultaneous coronary artery bypass grafting and bilateral carotid endarterectomy using an eversion technique. RESULTS: Concomitant coronary artery bypass grafting with bilateral carotid endarterectomy was performed urgently in 24 (73%) and electively in 9 (27%) patients. The average carotid artery cross-clamp and total perfusion times were 14.7 +/- 4.9 minutes and 123 +/- 29.2 minutes, respectively. The average length of stay in the cardiopulmonary intensive care unit was 4.2 +/- 14.2 days and total hospital stay was 16.2 +/- 20.5 days. Postoperative in-hospital stay was 14.9 +/- 20.3 days. There were no postoperative strokes. Twenty-one (64%) patients were discharged before the tenth postoperative day. Nonfatal postoperative complications occurred in 27% (9 of 33) of patients. The overall 30-day mortality was 6.1% (2 of 33) and that was unrelated to primary cardiac or cerebrovascular events. CONCLUSIONS: Favorable outcome supports the justification for performing concomitant coronary artery bypass grafting with bilateral carotid endarterectomies in selected patients.

The multidisciplinary approach to prevention and treatment of cardiovascular disease: creation of a vascular care network.

Vascular care, diagnosis, and intervention can be very complex. Multiple specialists commonly are involved in dealing with patients with systemic atherosclerotic disease. Although each specialist may provide state-of-the-art care with good result, it would be advantageous to minimize duplication of effort and thereby improve cost efficiency. Patients still could reap the benefit of all these disciplines if evaluated for their vascular complaint in a coordinated system. In doing so, atherosclerosis prevention with risk factor modification, as well as diagnosis and therapy for the presenting problem all can be simultaneously managed. This is the concept that has motivated groups such as our own to form a comprehensive vascular center. We describe our experience with establishing a vascular center and outline its benefits and limitations.

Long-term results in patients treated with thrombolysis, thoracic inlet decompression, and subclavian vein stenting for Paget-Schroetter syndrome.

PURPOSE: In an effort to minimize long-term disability related to effort thrombosis of the subclavian vein, selected patients were treated with thrombolysis, thoracic inlet decompression, percutaneous transluminal angioplasty (PTA), and subclavian vein stenting. We evaluated the long-term outcomes of patients treated with this algorithm. METHODS: Between 1994 and 2000, 23 patients were evaluated with effort thrombosis of the subclavian vein. Thrombolysis was instituted on an average of 9.4 days (range, 1-30 days) after initial onset of symptoms. Average time to clot lysis was 34 hours (range, 12-72 hours). After immediate supraclavicular thoracic inlet decompression, all patients underwent PTA. Fourteen patients with residual vein stenosis (>50%) after PTA underwent stenting of the subclavian vein. Complications in this series included three wound hematomas that required drainage in two patients and one subpleural hematoma that required thoracotomy for decompression. RESULTS: All patients who underwent PTA are patent, with a mean follow-up of 4 years (range, 2-6 years). In the veins treated with stents, 9 of 14 veins are patent, with a mean follow-up of 3.5 years (range, 1-6 years). Two veins had early occlusions (2 days); two veins occluded at 1 year; and seven veins occluded at 3 years. Three of the patients (including those patients who experienced the early failed procedures) were later identified with factor V Leiden. Early failures also had clot extending into the brachial vein. CONCLUSION: Patients with short-segment venous strictures after successful lysis and thoracic outlet decompression may safely be treated with subclavian venous stents and can expect long-term patency.

Outcomes with plantar bypass for limb-threatening ischemia.

Patients with severely diseased or occluded infrageniculate arteries, limited runoff, and tissue loss may often present for primary amputation. In this study, we review our experience with plantar artery revascularization when no other bypass options are feasible. All patients requiring infrainguinal bypass to the plantar artery level over the last 3 years were prospectively entered into our vascular surgery database. Indications, demographics, length of stay (LOS), outcome, and patency were reviewed. Our results showed that plantar artery bypass is a safe and reasonable alternative to primary amputation. Excellent limb salvage can be achieved if the bypass remains patent through the initial 30 days postoperatively.

Fungal pathogen protection in potato by expression of a plant defensin peptide.

Defensins are small cysteine-rich peptides with antimicrobial activity. We demonstrate that the alfalfa antifungal peptide (alfAFP) defensin isolated from seeds of Medicago sativa displays strong activity against the agronomically important fungal pathogen Verticillium dahliae. Expression of the alfAFP peptide in transgenic potato plants provides robust resistance in the greenhouse. Importantly, this resistance is maintained under field conditions. There have been no previous demonstrations of a single transgene imparting a disease resistance phenotype that is at least equivalent to those achieved through current practices using fumigants.

Reproductive tissue renin gene expression in preeclampsia.

OBJECTIVE: Using an analogy with renin gene overexpression, low-renin hypertension animal models, we wished to test the hypothesis that renin gene expression is increased in decidua basalis in human gestation with preeclampsia. METHODS: Human placentas were obtained immediately after delivery from 11 control (C) and 11 preeclamptics (PE). Tissue samples were microdissected and renin gene expression in decidua basalis (DB), chorionic villi (CV), and decidua vera (DV) was measured using dot-blot hybridization. RESULTS: Overall renin gene expression is highest in decidua basalis (mean +/- SEM, 2.66 +/- 0.69 densitometry area units) compared to chorionic villi (mean +/- SEM, 1.85 +/- 0.5) or compared to decidua vera (mean +/- SEM, 1.63 +/- 0.9) (both t-tests p = 0.001 two-tailed and analysis of variance p = 0.0001). Renin gene expression in DB and in CV was similar in both preeclamptic and normal pregnancies (DB mean +/- SEM C 2.79 +/- 0.96 versus PE 2.54 +/- 1.04, and CV mean +/- SEM C 2.11 +/- 0.91 versus PE, 1.59 +/- 0. 44). Renin gene expression in DV was approximately threefold higher in tissues from preeclamptics compared to control (mean +/- SEM PE 2. 44 +/- 1.76 versus C 0.82 +/- 0.42). Using the median value of 0.5 units for DV as cutoff, the preeclamptics displayed higher renin gene expression (chi square p = 0.033, two tailed). CONCLUSION: Our data suggest that renin gene expression is increased in preeclampsia in decidua vera. This may explain previously reported increased renin secretion in uterine circulation in preeclampsia.

Analysis of the effect of asymptomatic carotid atherosclerosis study on the outcome and volume of carotid endarterectomy.

Recent studies have demonstrated the benefits of carotid endarterectomy (CEA) and risk factor control in preventing stroke in asymptomatic patients. In this study, the effect of the asymptomatic carotid atherosclerosis study (ACAS) on the frequency of CEAs performed and the outcome of such procedures on symptomatic and asymptomatic patients were analyzed. From 1990 to 1996, all patients undergoing CEA were prospectively entered into a computerized vascular registry. The number of procedures, indications, demographics, and early and late results were analyzed and compared with similar data compiled prior to the ACAS study. The total volume of CEAs performed increased from 66 in 1990 to 719 in 1996 (ratio 1:12.3). The ratio of symptomatic to asymptomatic patients changed from 1.75:1 in 1990 to 1:1.52 in 1996. The combined stroke/mortality rate dropped from 4.75% in 1990 to 2.15% in 1996. The stroke mortality in the asymptomatic group decreased significantly from 4.3 to 1.9% in the pre and post-ACAS groups respectively (P<0.0005). The stroke mortality of symptomatic patients remained constant at 2.1 and 1.4% respectively.Since the completion of ACAS in 1993, the number of CEAs performed on our service has increased tenfold. An increase in volume has translated into an improved stroke/mortality rate and significantly decreased length of stay.

Use of shunts with eversion carotid endarterectomy.

PURPOSE: The purpose of this study was to examine the utility of carotid shunting in the context of eversion endarterectomy. A comparison of patients who underwent carotid endarterectomy by eversion with and without shunts was performed. METHODS: Over a 5-year period, 2724 eversion carotid endarterectomies were performed. In most of these operations patients were under cervical block anesthesia. A shunt was used in 112 eversion endarterectomies (4.1%). Cervical block anesthesia was used in 103 patients (92.0%), general anesthesia was used in 5 patients (4.5%), and 4 patients (3.6%) were converted from cervical block to general anesthesia intraoperatively. The indications for shunting were neurologic deterioration in 99 patients (88.4%) who were under cervical block anesthesia, procedures performed in neurologically unstable or otherwise compromised patients who were under general anesthesia, and the operator's discretion in the remaining eight patients. RESULTS: There was a combined stroke/death rate of 2.7% in the shunt group. These three cases included one death from myocardial infarction and one delayed death due to intracerebral hemorrhage after discharge. Shunt insertion was unrelated to the negative outcome in these two cases. One perioperative major stroke in the shunt group was identified. Follow-up averaged 12.3 months (range, 1-53 months). CONCLUSION: Carotid shunts can be used effectively in the context of eversion endarterectomy. Shunt insertion is not associated with an increased stroke/death rate in these patients.

Atheroemboli to the brain: size threshold for causing acute neuronal cell death.

OBJECTIVE: The objective of this study was to investigate the dilemma posed by the observations that carotid angioplasty dislodges significant numbers of plaque fragments but is reported to have a low rate of neurologic consequences. We examined the fragments released by ex vivo carotid angioplasty. The smaller and most numerous were separated by size and injected into rats to determine the tolerance of the brain to microemboli. METHODS: Ex vivo angioplasty was performed on a total of 20 human carotid plaques removed en bloc. Plaques were placed within polytetrafluoroethylene grafts, and three manipulations were performed: guide wire insertion, 3.5- or 4.0-mm balloon angioplasty, and 5-mm angioplasty with or without a Palmaz stent. After each manipulation, the lumen was flushed, effluent was collected, and fragments were counted under 100x magnification. Using 200-microm and 500-microm micropore mesh, we separated fragments by size into two groups: (1) less than 200 microm and (2) 200 to 500 microm. We then injected rats with saline alone (Group A), with 100 fragments less than 200 microm (Group B), or with 100 fragments 200 to 500 microm (Group C). Animals were euthanized at 1, 3, and 7 days, and brain sections were examined for cell viability and expression of HSP- 72. RESULTS: The total number of fragments dislodged from the plaques varied from 30 to 553. The mean number of fragments released with each manipulation was as follows: guide wire passage, 24; initial balloon angioplasty, 97; second balloon angioplasty, 68; and second angioplasty plus stent, 172. Sixteen of the 20 plaques dislodged fragments that were 1 mm or more in greatest dimension. There was no evidence of brain ischemia in Group A at any time. Group B also showed no injury at 1 or 3 days. However, injection of 200- to 500-microm fragments (Group C) caused a scattered pattern of neuronal cell death. At 7 days, brain sections from both Group B and Group C animals had a scattered pattern of ischemic neurons. There were no classic wedge-shaped infarctions. DISCUSSION: The brain appears to have a surprising tolerance for microembolization in the acute setting. Thus, carotid angioplasty may dislodge plaque fragments, but there may still be a low incidence of stroke. However, even small plaque fragments, less than 200 microm, may cause neuronal ischemia at later time points. Periprocedural microemboli could cause subtle neurologic dysfunction in late follow-up.