Embolic Load Research Articles

Use of the Reamer/Irrigator/Aspirator Decreases Carotid and Cranial Embolic Events in a Canine Model.

Approximately 2 million patients in the United States annually undergo total joint arthroplasty with reaming and placement of intramedullary nails, resulting in extravasation of bone marrow and fat into the circulatory system and potentially causing fat embolism syndrome. Acute and chronic changes in mental status documented after these procedures may be related to embolic events. The Reamer/Irrigator/Aspirator (RIA) device has been shown to decrease intramedullary pressure during reaming. We hypothesized that the use of the RIA in a canine model would reduce the number of microemboli detected in the carotid artery and brain compared with nailing either with or without reaming. Twenty-four large canines underwent unreamed nailing (UR), sequentially reamed nailing (SR), or RIA-reamed nailing (RIA) of bilateral femora (eight dogs per group). During reaming and nailing, the number and size of microemboli transiting the carotid artery were recorded. After euthanasia, the brain was harvested for immunostaining and measurement of microinfarction volumes. Total embolic load passing through the carotid artery was 0.049 cc (UR), 0.045 cc (SR), and 0.013 cc (RIA). The number and size of microemboli in the UR and SR groups were similar; however, the RIA group had significantly fewer larger-sized (>200-μm) emboli (p = 0.03). Pathologic examination of the brain confirmed particulate emboli, and histologic analyses demonstrated upregulation of stress-related proteins in all groups, with fewer emboli and less evidence of stress for RIA reaming. RIA reaming decreased microemboli compared with traditional reaming and unreamed nailing, suggesting that intramedullary pressure and heat are important variables. The documented embolic events and brain stress may help to explain subtle neurobehavioral symptoms commonly seen in patients after undergoing long-bone reaming procedures. RIA reaming decreased cranial embolic events and may have an ameliorating effect on postoperative neurologic sequelae.

Intraoperative Embolization and Cognitive Decline After Cardiac Surgery: A Systematic Review.

Since the advent of cardiac surgery, complications have existed in many forms. Recent work has focused on the safety of current cardiac surgery with particular emphasis on cognitive outcomes. Cardiopulmonary bypass has improved the safety of operative practice; however, increasing concern surrounds the measurable and immeasurable impact embolization has on the brain. New ischemic lesions have been associated with distant emboli, which intraoperatively enter the cardiovascular system. This has prompted better characterization of the nature of emboli manifesting as cognitive impairment postoperatively. The difficulty in attributing causation relates to the subclinical damage that does not necessarily manifest as clinical stroke. Transcranial Doppler has become an important tool in documenting cerebral emboli during surgery. The purpose of this systematic review is to focus on the current literature to improve our understanding of the impact embolization has on the brain. We also aim to investigate which cardiac interventions hold the greatest burden of embolic load and how previous literature has investigated the impact of emboli on cognition by monitoring emboli during specific cardiac interventions. Significant intraoperative factors such as the cardiopulmonary bypass machine and surgical interventions have been highlighted to summarize the current literature associating cerebral embolization with these factors and postoperative cognitive outcomes. The findings of this review report that the current literature is divided as to whether the impact of embolization during cardiac surgery has any adverse impact on cognition. This review highlights that the ultimate goal of improving cognitive safety will involve further careful consideration of multifactorial events.

Cardiovascular medical device evaluation of particulate following simulated use testing

Event Abstract Back to Event Cardiovascular medical device evaluation of particulate following simulated use testing Jeffrey Schwartz1 1 W. L. Gore & Associates, United States Introduction: Several FDA guidance documents for benchtop testing of cardiovascular devices have included particulate testing.[1][2] Counting of particulate following simulated use of a medical device can provide an understanding of the possible embolic load during a deployment. While these documents provide a good solid foundation for performing particle testing, there were no specific details of the actual test method set up. This paper will give an overview of the test method set up that has been used in light of the FDA recommendations. Materials and Methods: For a summary of the particle test method and considerations for particle testing, two references[3][4] are recommended. The final product for testing was a finished medical device (Devices A, C, and D) along with a device manufactured by another company (Device B). The untreated device was not coated while the remaining devices were coated with a thin, hydrophilic polymer to improve device performance. Two sizes of the device, 24 French (Fr) and 22 Fr, were included in this study. The effect of sterilization was evaluated by testing some of the devices both before and after sterilization (pre-process and post process). Testing was performed in a cleaned horizontal HEPA work bench to minimize background environmental particulate. Water and glassware beakers used for testing were verified to pass the USP 788 criteria.[5] Devices were prepared following their instructions for use (IFU) by flushing the inner lumen and rinsing the outer surface with filtered water. The device was inserted into a tortuous glass model based on geometry of 3D reconstructed CT scans taken from patient anatomy. The glass model was pre-filled with filtered water and the device was inserted as far as possible. The device was then retracted and inserted as necessary to mimic delivery within the patient. The device was left within the model while the filtered water was drained and collected in a cleaned test beaker. Filtered water that was collected in a reservoir above the model was released in order to provide physiological flow conditions. Rinses were repeated to sufficiently remove the particulate from the device and glass model. Finally the device was removed and a final rinse of the glass model was performed. All rinses were deposited into the collection beaker and this combined volume was tested using a light obscuration particle counter following USP 788 testing conditions. Results and Discussion: The test method was sufficient to differentiate between medical devices as shown in Figure 1. In addition to differentiating between the untreated device and the other devices tested, the test was able to determine a difference before and after sterilization for both sized devices pre and post process. Finally, a trend of lower particle values for the smaller device size was observed. Following particle testing, additional examination of the particles could be performed as recommended by AAMI TIR42:2010 for determining particle origin.[6] Figure 1 Particle Count Comparison between Cardiovascular Medical Devices Conclusion: A method for testing a cardiovascular medical device for particulate following simulated use was described that followed FDA guidelines and provided further specifics for the test.

Effect of Core Temperature and Embolic Load During Cardiac Surgery on Motion Perception

Cognitive decline post-cardiac surgery is of clinical concern. To better understand it a sensitive and specific measure of post-surgery brain impairment is required. The cerebral territory most likely to be adversely affected by surgery is the posterior "watershed" territory. We have designed a psychophysical task involving reading letters defined by motion aimed at measuring the integrity of a cortical area (MT) located in this territory. Patients undergoing coronary artery bypass grafting (CABG) and a healthy control group were given the psychophysical test twice, pre- and post-surgery for the patient group. There was no overall difference in performance between the surgery group and the control group at either pre- or post-surgery testing. However, multivariate analysis of surgical variables such as body temperature and embolic load to the brain as measured by Transcranial Doppler showed that patients with warmer core temperatures and higher embolic loads performed significantly worse on the motion defined letter reading tasks than those with more favourable surgical variables. These results demonstrate that high embolic load and warm core body temperatures lead to poor motion perception post-cardiac surgery, implying damage to the posterior watershed cortex.

Digital Carotid Compression: A Simple Method to Reduce Solid Cerebral Emboli During Cardiac Surgery.

Serious neurologic injury can be attributed to embolization of solid particles into cerebral vessels during cardiac surgery. Previous studies using transcranial Doppler (TCD) identified arterial cannulation and aortic declamping to be associated with cerebral embolization. The purpose of this study was to investigate the impact of transient compression of the carotid arteries during these maneuvers on the embolic load during cardiac surgery with cardiopulmonary bypass. Prospective, randomized, clinical trial/pilot study. Single-center study at a university hospital. Patients with multiple types of procedures were included and they were prospectively, randomly assigned to group I (n = 20, carotid compression during arterial cannulation and aortic declamping) and group II (n = 20, no carotid compression). Bilateral continuous monitoring of the middle cerebral arteries was performed with a multirange, multifreqency transcranial Doppler (DopplerBoxX, DWL, Singen, Germany), allowing for discrimination between solid and gaseous emboli. For aortic cannulation the carotid arteries were compressed for 5 seconds and for declamping for 3 seconds, and microemboli signals were detected within the following 45 seconds. A reduction of intraoperative solid emboli was detected in group I compared with group II (26±16 v 38±18; p = 0.04). Looking specifically at the maneuver of arterial cannulation, the observed difference was 0.5±0.8 in group I versus 5.7±5.8 in group II (p<0.0001). During aortic declamping, 6.6±6.2 emboli were encountered in group I and 10.8±5.2 in group II (p = 0.02). The incidence of neurologic events was not significantly different between groups (2 patients in group II had pathologic changes on magnetic resonance imaging). The data of this preliminary trial demonstrated that transient compression of the carotid arteries during arterial cannulation and aortic declamping led to a decreased number of solid cerebral emboli. Further prospective, randomized clinical studies should be undertaken to investigate the influence of transient carotid artery compression during specific surgical procedures.

Is Total Knee Arthroplasty a Viable Treatment Option in Octogenarians with Advanced Osteoarthritis?

PurposeThis study directly compared clinical assessment scores and short-term systemic complications after total knee arthroplasty (TKA) between a group of patients aged 80 or older (141 patients) and another group of patients aged between 65 and 70 years (616 patients) with advanced osteoarthritis.Materials and MethodsWe retrospectively investigated 757 osteoarthritic patients who underwent primary TKA from January 2007 to January 2011 with a follow-up of 1 year. The surgery was performed using an extramedullary alignment guide instrument without invasion of the intramedullary canal to decrease embolic load and blood loss.ResultsAt 1 year after surgery, the mean Knee Society knee score was improved in both groups (from 63.6 to 83.2 in octogenarians and from 68.3 to 89.0 in the younger group) and the level of satisfaction was excellent in both groups (8 in octogenarians and 8.3 in the younger group), even though there was no notable change in function score in the octogenarians (from 61.0 to 61.9 in the octogenarians and from 62.3 to 73.6 in the younger group). The total incidence of systemic complications (3.4% vs. 1.2%, p=0.400) and surgical complications (2.1% vs. 0.5%, p=0.229) showed no significant difference between groups.ConclusionsTKA yielded favorable clinical outcomes with a comparatively low postoperative complication rate in octogenarians despite the negligible functional improvement.

Incidence and Mechanisms of Cerebral Ischemia After Transcatheter Aortic Valve Implantation Compared With Surgical Aortic Valve Replacement

The most likely mechanisms of neurologic injury after transcatheter aortic valve implantation (TAVI) and aortic valve replacement (AVR) are cerebral embolization and hypoperfusion. We set out to determine potential mechanisms of neurologic injury after TAVI compared with AVR. One hundred twenty-seven consecutive high-risk patients with severe aortic stenosis (AS) who underwent TAVI (n= 85) or AVR (n= 42) were studied. Transcranial Doppler ultrasound (TCD), cerebral oximetry, diffusion-weighted magnetic resonance imaging (DW-MRI) (before, 6 days, and 3 months after procedure), and neurocognitive assessment before and at 3 months were performed. Neurologic injury was not significantly different between TAVI and AVR at 1 (1.1% vs 2.2%, p= 0.25) and 3 months (4.7% vs 2.2%, p= 1). At 3 months, overall cognitive score was higher in AVR compared with TAVI when adjusted for baseline score; the estimated difference between groups was 0.63 (95% confidence interval 0.87% to 1.17%; p= 0.02). Cerebral embolic load was 212 (123 to 344) during AVR and 134 (76 to 244) during TAVI (p= 0.07). Cerebral oxygen desaturation during AVR (7.56 ± 2.16) was higher compared with TAVI (5.93 ± 2.47) (p < 0.01). Ischemic lesions measured by DW-MRI occurred in 76% of TAVI and 71% of AVR patients at 6 days (p= 0.69) and 63% and 39% at 3 months (p= 0.11). No significant association was found between cerebral emboli, cerebral oxygen desaturation, brain ischemic lesions, and general cognitive score. At 3 months follow-up, overall cognitive score was higher in AVR compared with TAVI, adjusted for baseline score. However, there was no difference in cerebral embolic load, ischemic lesions, and oxygen desaturation.

EComment. Delirium after cardiac surgery: incidence and risk factors

Smulter et al. provide a very detailed study on an important postoperative issue following cardiac surgery, that is associated with increased morbidity and mortality [1]. Their work, however, raises a number of issues. Smulter et al. identified maximum temperature in the intensive care unit as a risk factor for delirium. As hyperpyrexia is caused by an excessive inflammatory response, this finding is not unexpected. However, no mention is made of the rate of rewarming and the maximum temperature at the end of cardiopulmonary bypass (CPB). Both the rate and the final temperature are known risk factors post-CPB for cerebral damage [2]. A difference exists with regard to cerebral embolic load and whether a cardiac procedure is open (valve replacement), or closed [coronary artery bypass surgery (CABG)]. No mention is made about whether open or closed procedures were utilised as independent covariates in their analysis. We would recommend that isolated CABG should be separately analysed from isolated valve procedures, as they are fundamentally different operations with regard to neurological risk [3]. The identification of sodium as an independent risk factor for postoperative delirium confirms previous work [4]. Valve replacement patients are more likely to suffer from this complication secondary to diuretic therapy. Unfortunately, preoperative sodium levels were not reported. Identification of volume loading during surgery as being a significant risk factor raises the possibility of reduced oxygen delivery being an issue. Quantifying reduced oxygen delivery is difficult, and may involve epoch analysis [5]. The finding of gastritis and peptic ulcer history as a significant risk factor is difficult to interpret, as pointed out by Smulter et al. No comment on an interaction analysis with other covariates was mentioned. In our practice, urgent (not emergency) CABG patients have a high incidence of gastric issues secondary to intense dual antiplatelet therapy. Urgent CABG is a known risk factor for neurological issues. As the Mini-Mental State Examination (MMSE) and the Organic Brain Syndrome Scale (OBS) used are linear scales, and delirium is not a binary issue, it would be interesting if multiple linear regression analysis would reveal the same risk factors as logistic regression, as used by Smulter et al. With regard to the logistic regression, it is customary to use a maximum of 10 events per covariate. In this study, this would limit covariate numbers to a maximum of 8, however, 18 variables from univariate analysis were utilised to develop their final model of 7 variables. Conflict of interest: none declared

EComment. Stroke rate after surgical myocardial revascularization

I read with great interest the paper by Takagi et al. in which they tried to answer an important question: Does off-pump coronary artery bypass grafting (CABG) increase the risk of repeat coronary revascularization when compared with on-pump CABG? [1]. Data from this meta-analysis confirm that the decreased benefits from on-pump CABG is attributable to the higher incidence of fewer bypass grafts and lower graft patency yielding incomplete and repeat revascularization with this technique. In this valuable meta-analysis, I think that there is yet another topic to be discussed. Proponents of off-pump CABG have claimed that this technique limits the rate of postoperative stroke by avoiding aortic cannulation/decannulation, micro-gaseous and small particulate emboli from the pump circuit and aortic cross-clamping. Off-pump technique does not totally eliminate the necessity for aortic clamping. However, in beating heart operations with no-touch aorta technique, cerebral embolic load is completely reduced by avoiding aortic cross-clamping. Yet, there is still the hazard for neurological insult related to periods of hypotension during manipulation of the heart. Three large clinical trials have been conducted recently comparing outcomes in cardiac surgery patients using off-pump and on-pump strategy. The Randomized On/Off Bypass (ROOBY) trial [2] is a single-blinded randomized trial involving 2203 patients in 18 Veterans Affairs medical centres. There was no significant difference between off-pump and on-pump CABG in the rate of the 30-day stroke (1.3% and 0.7%, respectively; P = 0.28). Recently, the results of the Coronary Artery Bypass Surgery Off or On Pump Revascularization Study (CORONARY) [3] has been published. This prospective study involved 4752 patients randomized to either on- or off-pump CABG in 79 centres and 19 countries. The use of off-pump CABG, as compared with on-pump CABG, did not reduce the rate of non-fatal stroke (1.0% vs 1.1%, respectively; P = 0.89) at 30 days or at one year (1.5% vs 1.7%, respectively; P = 0.24). Diegeler et al. reported their results from the German Off-Pump Coronary Artery Bypass Grafts in Elderly Patients (GOPCADE) trial [4]. This trial attempts to define the potential benefits of OPCAB in an elderly group (aged more than 75 years) with multiple comorbidities. The study involved 2539 patients from 12 centres. There was no significant difference between patients who underwent off-pump surgery and those who underwent on-pump surgery in terms of rate of stroke (2.2% vs 2.7%, respectively; P = 0.47) at 30 days or at one year after randomization (3.5% vs 4.4%, respectively; P = 0.26). Of note, the higher stroke rate in the last trial is attributed to the increased operative risk of the study population. None of these large randomized trial could demonstrate any superiority of off-pump CABG over on-pump CABG in terms of reduced risk of CABG-related stroke. Nevertheless, data regarding quality of the proximal aorta and cross-clamping technique of the aorta are lacking in these trials. Preoperative and intraoperative screening can identify extensive atherosclerosis of the ascending aorta. Selective use of off-pump no-touch aorta CABG in this group of high-risk patients can prevent adverse neurologic injury. Conflict of interest: none declared

Single aortic clamping in coronary artery bypass surgery reduces cerebral embolism and improves neurocognitive outcomes

Aortic manipulation releases embolic material, thereby enhancing the probability of adverse neurologic outcomes following coronary artery bypass grafting (CABG). We prospectively evaluated 59 patients undergoing CABG. Patients in the single (SC, n = 37) and multiple clamp (MC, n = 22) groups were comparable in relation to age and operative risk (p > 0.05). Neurocognitive evaluation consisted of the Auditory Verbal Learning Test (AVLT), Color Trails Test A, the Grooved Pegboard test and the Mini-Mental State Examination. Data acquisition was performed preoperatively, early postoperatively and at the 4-month follow-up. Intraoperative transcranial Doppler (TCD) monitoring was used to quantify the embolic load in relation to different aortic clamping strategies. Preoperative neurocognitive results were similar between the groups (p > 0.05). The incidence of postoperative delirium was greater in the MC group but this failed to reach statistical significance (23% vs 8%, p = 0.14). SC patients had fewer embolization signals (270 ± 181 vs 465 ± 160, p < 0.0001). Early postoperative neurocognitive results were depressed in comparison to preoperative values in both groups (p < 0.05 for multiple comparisons). The magnitude of this cognitive depression was greater in the MC group (p < 0.05 for multiple comparisons). Preoperative levels of neurocognition were restored at follow-up in the SC group in all tests except the AVLT. A trend towards improvements in neurocognitive performances at follow-up was also observed in the MC group. Residual attention, motor skill and memory deficits were, however, documented with multiple tests. In conclusion, the embolic burden was significantly lower in the SC group. This TCD imaging outcome translated into fewer early cognition deficits and superior late restoration of function.

Reduced embolic load during clinical cardiopulmonary bypass using a 20 micron arterial filter

To compare the efficiency of 20 and 40 µm arterial line filters during cardiopulmonary bypass for the removal of emboli from the extracorporeal circuit. Twenty-four adult patients undergoing surgery were perfused using a cardiopulmonary bypass circuit containing either a 20 µm or 40 µm arterial filter (n = 12 in both groups). The Emboli Detection and Classification system was used to count emboli upstream and downstream of the filter throughout cardiopulmonary bypass. The mean proportion of emboli removed by the filter was compared between the groups. The 20 µm filter removed a significantly greater proportion of incoming emboli (0.621) than the 40 µm filter (0.334) (p=0.029). The superiority of the 20 µm filter persisted across all size groups of emboli larger than the pore size of the 40 µm filter. The 20 µm filter removed substantially more emboli than the 40 µm filter during cardiopulmonary bypass in this comparison.

Vacuum Assist: Angel or Demon CON

Vacuum-assisted venous drainage (VAVD) to enhance venous return during cardiopulmonary bypass (CPB) was described as early as 1958 but was not widely used until the late 1990s. VAVD was initially used to facilitate the use of smaller cannulas with ministernotomy but was increasingly used to allow reduction in CPB circuit size while maintaining CPB flow rates. This innovation was made without planned consideration to CPB circuit design, most critically that of the venous reservoir. Clinical reports of prime reduction facilitated by VAVD in both adult and pediatric CPB were associated with reduced nadir hematocrit and rates of transfusion that encouraged the proliferation of VAVD in CPB. Concomitantly, investigators have reported both in vitro and in vivo significantly increased arterial emboli associated with the use of VAVD, mostly related to accelerated venous air entrainment. In vitro studies continue to confirm this association and likely underestimate the resulting embolic load as a result of flawed study design. While the evidence for VAVD is equivocal, our understanding of the clinical impact of gaseous microemboli in CPB is similarly limited, most likely confined to blood–brain barrier disruption. It is only after two decades that CPB component design is receiving serious attention in terms of air handling. The ethics of innovation in the field of CPB warrant careful consideration. The application of VAVD is not without consequence.

Abstract No. 413 - Embolization of the gastroduodenal and right gastric arteries prior to radioembolization with glass microspheres: is it always necessary?

Purpose Prior to radioembolization with yttrium-90 (Y90), it is standard practice to coil embolize the gastroduodenal (GDA) and right gastric (RGA) arteries to mitigate complications from non-target delivery of radioactive microspheres to the gastrointestinal tract. The aim of this study is to evaluate the necessity of prophylactic embolization of the GDA and RGA prior to radioembolization with glass microspheres (extended shelf-life). Materials and Methods Consecutive patients with unresectable hepatocellular carcinoma (HCC) or liver metastases undergoing radioembolization with extended shelf-life glass microspheres were studied. Extended shelf-life microspheres were chosen secondary to their increased embolic load over standard glass microsphere dosimetry. The rate and location of RGA/GDA coil embolization during planning angiography was recorded. After Y90 treatment, clinical follow-up was performed at 1-month and every 3 months thereafter. Results 134 patients with HCC or liver metastases were treated with extended shelf-life glass microspheres. Neither the GDA nor the RGA were coil embolized in 68.6% (n=92) of patients. The RGA was coil embolized in 26.1% (n= 35) of patients, and the GDA was coil embolized in 14.2% (n=14) of patients. Two patients (1%) developed gastrointestinal ulcers, both of which healed with conservative therapy. In one case, retrospective analysis of the angiogram demonstrated a small gastric vessel that was overlooked by the interventional radiologist. The microcatheter was placed proximal to the RGA at the time of treatment, resulting in non-target delivery of radioactive microspheres. The other patient developed an ulcer after 6 weeks of being asymptomatic; biopsy did not reveal microspheres. The ulcer healed with conservative measures. Conclusion Y90 radioembolization with glass microspheres using the extended shelf-life dosimetry model is minimally embolic. This study shows that coil embolization of the GDA and/or RGA may not be mandatory to mitigate GI complications. Rather, prophylactic embolization of these vessels should be at the IR’s discretion, taking into consideration blood flow dynamics and catheter infusion position.

Evaluation of embolic protection devices for fat emboli prevention.

Patients with acutely treated femoral shaft fractures with reamed intramedullary nailing are at risk for acute respiratory distress syndrome due to liberation of bone marrow fat particles that travel to the lung and cause damage to the parenchyma. The purpose of this study was to demonstrate: (1) the ability of clinically applicable embolic protection devices to capture such particles; (2) how such a device affects cardiopulmonary function after reamed intramedullary nailing; and (3) evaluation of lung pathology to determine whether filtration affects pulmonary embolic load. A total of 12 canines were anesthetized, and hemodynamic monitoring was established. Carotid embolic protection devices were introduced into the iliac vein, and ipsilateral intramedullary reaming and nailing was performed. Cardiopulmonary parameters were recorded at timed intervals up to 60 minutes after the procedure. The control group (n=4) was compared with groups treated with Accunet (n=4) and Spider (n= 4) filters. A blinded histopathological review was performed on lung specimens to determine the average number of emboli per section and to measure the area (mm(2)) of embolic load by digital image analysis. Gross inspection of the embolic protection devices showed the presence of bone marrow debris. A significant change was observed in pH levels (control= -0.052, filters=+0.005; P< .05) within the 60 minutes after intramedullary nailing. Serum bicarbonate (meq/dL) values were noted to have similar changes of -2.7 and -1.8 at 10 and 60 minutes, whereas the experimental group was+0.6 and+0.8 at the same time intervals (P=.01 and .0004, respectively). Pulmonary measurements for pO2 and oxygen saturation were analogous to the serum parameters with decreases in the control group in comparison with the filter groups. The mean numbers of emboli and area measurements of embolic load were significantly reduced in the filter group (all P< .01). Embolic protection devices were effective in capturing embolic debris from reamed intramedullary nailing of lower extremity long bones and demonstrated a protective effect on pulmonary function and significantly decreased the number and size of emboli in the lung. Based on these findings, patients with long bone fractures at risk for pulmonary complications and acute respiratory distress syndrome could benefit from the placement of embolic protection devices prior to intramedullary fixation. While this study utilized filtration devices designed for carotid embolic protection, further study is warranted to determine optimal filter design in this setting.

Cognitive function after transapical aortic valve implantation: a single-centre study with 3-month follow-up

Reports on adverse neurological events following transcatheter aortic valve implantation (TAVI) have focused on strokes, while more subtle postoperative cognitive decline has not yet been systematically investigated. In this study, we prospectively examined neurological and cognitive outcomes in patients undergoing transapical (TA) and surgical aortic valve replacement (AVR). A total of 64 patients with severe symptomatic aortic stenosis were investigated between January 2008 and July 2009. Clinical neurological examination and comprehensive neuropsychological testing were performed before and after the procedure, at discharge and at 3-month follow-up. Diffusion-weighted magnetic resonance imaging (DW-MRI) was applied to detect morphological brain injury. TA-TAVI patients (n = 27) were older and at higher surgical risk compared with surgical AVR patients (n = 37; mean age 82.2 ± 4.7 vs 67.5 ± 8.9 years; log EuroSCORE 36.4 ± 13.2 vs 2.6 ± 8.5%, both P <0.001). There was one stroke in each group (3.7 vs 2.7%, P = 0.49), both classified as embolic based on imaging characteristics. After TA-TAVI, cognitive tests showed no decline during follow-up, while, after AVR, 7 of 11 tests showed a decline early after surgery. Similarly, with-in patient analysis showed that the rate of individuals with clinically relevant cognitive decline was increased early after AVR (TA-TAVI vs AVR: 18 vs 46% at discharge [P = 0.03]; 28 vs 6% at 3 months [P = 0.04]). New focal ischaemic cerebral lesions were detected on DW-MRI in 58% (7 of 12) of patients after TA-TAVI vs 34% (12 of 35) after AVR (P = 0.13). The number of brain lesions per patient and cumulative embolic load per patient were similar between groups. An association between postoperative cerebral ischaemia and cognitive dysfunction was not found (odds ratio 2.37, 95% confidence interval 0.05-113.75, P = 0.66). Cognitive function was only mildly impaired after TA-TAVI when compared with a marked, albeit transient, decline after surgical AVR. Focal embolic brain injury tended to occur more frequently after TA-TAVI, but this was not related to cognitive decline during the 3-month follow-up.

Investigation into Causes of Abnormal Cerebral MRI Findings Following PVAC Duty‐Cycled, Phased RF Ablation of Atrial Fibrillation

Left atrial catheter ablation of the pulmonary veins (PVs) is an established option for patients with atrial fibrillation (AF). Asymptomatic cerebral emboli (ACE) detected by diffusion weighted MRI (DW-MRI) following AF ablation has been reported at varying rates. This variability may be linked to procedural variables and demographic risk factors. Animal studies with the multielectrode pulmonary vein ablation catheter (PVAC) have identified potential sources of emboli, including air introduced during PVAC introduction, inadequate anticoagulation, and high current densities when the distal (E1) and proximal (E10) electrodes are in contact. We sought to evaluate the incidence, size, and number of DW-MRI findings with procedural modifications that potentially reduce the embolic load. Thirty-seven AF patients (59 ± 10 years, 73% male, all with paroxysmal AF, left atrial [LA] diameter 44 ± 7 mm, left ventricular ejection fraction 57 ± 7%) underwent MRI sequences preceding ablation, within 24 hours postablation, and at 4-6 weeks. During the procedure all patients were on uninterrupted phenprocoumon, an attempted activated clotting time (ACT) level >300 seconds, had the PVAC introduced under saline, and antral ablation was started with a 2:1 bipolar/unipolar mode. Files from the ablation unit (GENius v14.4) were retrospectively analyzed to determine the relationship between E1 and E10 in close proximity and DW-MRI findings. Post procedure, 10/37 patients (27%) were positive for new DWI cerebral lesions. Nine of 10 patients had a single lesion, and 1/10 patient had 2 lesions. Average lesion size was 3.1 ± 3.9 mm (2-14 mm). One of 10 (10%) had lesions at MRI follow-up. No neurological symptoms were observed. Eighteen of 37 (49%) of procedures had evidence of E1/E10 interaction. In the subgroup of patients with and without E1 and E10 in close proximity, the DW-MRI rate was 8/18 (44%) and 2/19 (11%), respectively (P = 0.029). The source of positive DW-MRI findings in LA ablation involves several factors. Controlling anticoagulation and careful sheath management helps to reduce the number and size of DW-MRI lesions. With the PVAC catheter, an ablation with the E1 and E10 in close proximity increases the risk of a DW-MRI finding. In the future, electrodes E1 and E10 should be kept apart to help reduce the incidence of acute ACE.

The Physiologic and Pathologic Effects of the Reamer Irrigator Aspirator on Fat Embolism Outcome

Intramedullary reaming of long bones before nail insertion has been known to cause an increase in fat emboli introduction into the bloodstream, which is a potentially fatal phenomenon. The goal of this study was to assess whether the reamer irrigator aspirator (RIA) reamer can reduce fat embolic load compared with the standard AO reamer. Fifteen pigs were prepared using an intravenous catheter inserted into the marginal ear vein for fluid balance and drug administration. One third of the pig's blood volume was withdrawn to simulate hemorrhagic shock. Each animal underwent bilateral retrograde femoral reaming, cementing, and nailing using either an RIA or AO reamer. Assignment of a reamer type to the left or right side was done randomly and allowed for direct comparison of matching femur results. Outcome measures were obtained, namely, pulmonary arterial pressure, mean arterial pressure, partial pressure of arterial oxygen, and cardiac output. Staining techniques were used to ascertain fat emboli counts from lung tissue samples. For mean arterial pressure, partial pressure of arterial oxygen, and cardiac output after cement injection, the RIA reamer group showed statistically higher values than the AO reamer group. In corollary, the RIA showed statistically lower pulmonary arterial pressure levels. No differences were noted at baseline, during hypovolemia, and post resuscitation. With the Student t test, no statistical differences were found between reamers regarding fat emboli counts for both staining methods. With the Mann-Whitney test, the RIA reamer showed statistically fewer emboli (7.0 versus 74.5) (P = 0.02, Z = 2.33) using Oil Red "O" staining. The RIA reamer demonstrated superior results with respect to physiologic measures and fat emboli counts and may provide optimal results compared with the AO reamer.

Comparison of Embolic Load in Femoropopliteal Interventions

To compare the incidence of distal emboli occurring during percutaneous transluminal angioplasty (PTA) and primary stent on the superficial femoral artery (SFA) METHODS: A total of 50 consecutive patients were entered in a prospective, randomized trial. Inclusion criteria were the presence of symptomatic limb ischemia due to stenosis or occlusion of the SFA. An embolic protection device was placed in the popliteal artery. The patients were then randomly assigned to undergo primary stent implantation or PTA. The filters were retrieved and sent for histologic examination. Stenting in the SFA produced more emboli (1.44 mm(3)) than PTA (0.772 mm(3)), P = .031. Reanalyzing the patients according to actual treatment performed, volume of debris in the stent group was 1.271 mm(3) and in the PTA group was 0.191 mm(3), P = .00087. Volume of embolized material during endovascular interventions in the SFA-above-knee popliteal artery is higher when a stent is used.

Filter content after carotid angioplasty and stenting: Relation to ischemic lesions in diffusion-weighted imaging

ObjectivesTo evaluate the relation between the material retrieved from distal filters after carotid angioplasty and stenting (CAS) and the development of ischemic brain lesions in diffusion-weighted imaging (DWI).To determine the influence of demographic, clinical, and procedural variables in the pathogenesis of emboli and in ischemia after CAS. Material and methodsWe submitted the contents of the filters of 76 patients (60 men; mean age, 68.39 years; range, 46–82) who had undergone angioplasty and stenting for severe stenosis of the internal carotid artery (ICA) for histologic analysis evaluating volume (<1λ=0.001ml=1μl; 1–10λ; and >10λ) and the composition of the particles. All patients underwent DWI before and 24h after the procedure; we recorded whether lesions appeared, their number, size, and distribution. We correlated the findings with demographic, clinical, and procedural variables. ResultsSymptoms were present before the procedure in 58 (76.3%) patients. Particles were present in 49 (64.5%) of the filters; most particles (77.5%) were 1λ with a predominance of fibrin-platelet aggregates, cell remnants, and cholesterol crystals. DWI after the procedure detected lesions in 12 (15.8%) patients. We found no statistically significant correlation between filter contents and lesion detection after the procedure or between filter contents and other variables. ConclusionsIschemia after CAS does not depend solely on the embolic load and its nature. We consider that the lower prevalence of postprocedural lesions in our series compared to others suggests that appropriate patient selection and experience minimize the negative influence of some variables like age in their development.

Evaluation of echogenic emboli during total knee arthroplasty using transthoracic echocardiography

Tranesophageal echocardiography or direct sampling of arterial and/or right atrial blood with histological evaluation are invasive techniques used to evaluate embolic material entering the heart during total knee arthroplasty (TKA). The aim of this study was to develop a non-invasive method of detecting and quantifying the embolic matter using transthoracic echocardiography and to apply this method to compare the incidence and severity of embolism between computer-navigated (N) and conventional (C) TKA done under tourniquet. Twenty-eight patients (15 N-TKA and 13 C-TKA) were enrolled. Transthoracic echocardiography was performed in all standard views prior to surgery and continuously after the tourniquet release for monitoring the echodense particulates appearing in the right atrium. To estimate the severity of echogenic embolization, maximum absolute increase in luminosity after tourniquet release (peak embolic load) and area under the curve (AUC; total embolic load) were both calculated. Twenty-four (85%) had significant particulate matter in right atrium (median time from release of thigh tourniquet to peak embolization in right atrium: 18.0 s). Peak embolic load was lower in N-TKA than C-TKA [17.0 versus 35.0 arbitrary luminosity units, p = 0.03]. Total embolic load, by area under the curve, was lower in the N-TKA group. Perioperative particulate embolization during TKA can be quantified non-invasively with the use of transthoracic echocardiography and off-line image analysis. N-TKA, by virtue of avoiding intramedullary guides, causes lesser total embolic load and hence can lead to decreased the severity and incidence of this potentially fatal phenomenon. II.