Experimental Evaluation of Immediate Recanalization Effect and Recanalization Efficacy of a New Thrombus Retriever for Acute Stroke Treatment In Vivo

BACKGROUND AND PURPOSE: Currently, several new stent retriever devices for acute stroke treatment are under development and early clinical evaluation. Preclinical testing under standardized conditions is an important first step to evaluate the technical performance and potential of these devices. The aim of this study was to evaluate the immediate recanalization effect, recanalization efficacy, thrombus-device interaction, and safety of a new stent retriever intended for thrombectomy in patients with acute stroke. MATERIAL AND METHODS: The pREset thrombectomy device (4 × 20 mm) was evaluated in 16 vessel occlusions in an established swine model. Radiopaque thrombi (10-mm length) were used for visualization of thrombus-device interaction during application and retrieval. Flow-restoration effect immediately after deployment and after 5-minute embedding time before retrieval, recanalization rate after retrieval, thromboembolic events, and complications were assessed. High-resolution FPCT was performed to illustrate thrombus-device interaction during the embedding time. RESULTS: Immediate flow restoration was achieved in 75% of occlusions. An increase or stable percentage of recanalizations during embedding time before retrieval was seen in 56.3%; a decrease, in 12.5%; reocclusion of a previously recanalized vessel, in 18.8%; and no recanalization effect at all, in 12.5%. Complete recanalization (TICI 3) after retrieval was achieved in 93.8%; partial recanalization (TICI 2b), in 6.2%. No distal thromboembolic events were observed. High-resolution FPCT illustrated entrapment of the thrombus between the stent struts and compression against the contralateral vessel wall, leading to partial flow restoration. During retrieval, the thrombus was retained in a straight position within the stent struts. CONCLUSIONS: In this experimental study, the pREset thrombus retriever showed a high recanalization rate in vivo. High-resolution FPCT allows detailed illustration of the thrombus-device interaction during embedding time and is advocated as an add-on tool to the animal model used in this study.

Effect of acceleration forces during transport through a pneumatic tube system on ROTEM® analysis

ROTEM® is considered a helpful point-of-care device to monitor blood coagulation in emergency situations. Centrally performed analysis is desirable but rapid transport of blood samples is an important prerequisite. The effect of acceleration forces on sample transport through a pneumatic tube system on ROTEM® should be tested at each institution to exclude a pre-analytical influence. The aims of the present work were: (i) to investigate the effect of pneumatic tube transport on ROTEM® parameters; (ii) to compare blood sample transport via pneumatic tube vs. manual transportation; and (iii) to determine the effect of acceleration forces on ROTEM® parameters.

Point-of-care prothrombin time testing in paediatric intensive care: an observational study of the ease of use of two devices

Two major difficulties arise when taking blood samples in children: the challenge of venous access and the comparatively large amount of blood required.

Radiation exposure in whole-body computed tomography of multiple trauma patients: bearing devices and patient positioning

Whole-body computed tomography (WBCT) plays an important role in the management of severely injured patients. We evaluated the radiation exposure of WBCT scans using different positioning boards and arm positions.

Continuous Formation and Separation of Calcium-Alginate Capsules Containing Viable Mammalian Cells in Microfluidic Devices

Microfluidic devices can be used for many applications, including the formation of well-controlled emulsions. In this study, the capability to continuously create monodisperse droplets in a microfluidic device was used to form calcium-alginate capsules.Calcium-alginate capsules have many potential uses, such as immunoisolation of cells and microencapsulation of active drug ingredients or bitter agents in food or beverage products. The gelation of calcium-alginate capsules is achieved by crosslinking sodiumalginate with calcium ions. Calcium ions dissociated from calcium carbonate due to diffusion of acetic acid from a sunflower oil phase into an aqueous droplet containing sodium-alginate and calcium carbonate. After gelation, the capsules were separated from the continuous oil phase into an aqueous solution for use in biological applications. Typically, capsules are separated bycentrifugation, which can damage both the capsules and the encapsulated material. A passive method achieves separation without exposing the encapsulated material or the capsules to large mechanical forces, thereby preventing damage. To achieve passiveseparation, the use of a microfluidic device with opposing channel wa hydrophobicity was used to stabilize co-laminar flow of im of hydrophobicity is accomplished by defining one length of the channel with a hydrogel. The chosen hydrogel was poly (ethylene glycol) diacrylate, which adheres to the glass surface through the use of self-assembled monolayer of 3-(trichlorosilyl)-propyl methacrylate. Due to the difference in surface energy within the channel, the aqueous stream is stabilized near a hydrogel and the oil stream is stabilized near the thiolene based optical adhesive defining the opposing length of the channel. Passive separation with co-laminar flow has shown success in continuously separating calcium-alginatecapsules from an oil phase into an aqueous phase. In addition to successful formation and separation of calcium alginate capsules,encapsulation of Latex micro-beads and viable mammalian cells has been achieved. The viability of encapsulated mammalian cells was determined using a live/dead stain. The co-laminar flow device has also been demonstrated as a means of separating liquid-liquidemulsions.

Control of ventricular unloading using an electrocardiogram-synchronized Thoratec paracorporeal ventricular assist device

OBJECTIVE: Current pulsatile ventricular assist devices operate asynchronous with the left ventricle in fixed-rate or fill-to-empty modes because electrocardiogram-triggered modes have been abandoned. We hypothesize that varying the ejection delay in the synchronized mode yields more precise control of hemodynamics and left ventricular loading. This allows for a refined management that may be clinically beneficial. METHODS: Eight sheep received a Thoratec paracorporeal ventricular assist device (Thoratec Corp, Pleasanton, Calif) via ventriculo-aortic cannulation. Left ventricular pressure and volume, aortic pressure, pulmonary flow, pump chamber pressure, and pump inflow and outflow were recorded. The pump was driven by a clinical pneumatic drive unit (Medos Medizintechnik AG, Stolberg, Germany) synchronously with the native R-wave. The start of pump ejection was delayed between 0% and 100% of the cardiac period in 10% increments. For each of these delays, hemodynamic variables were compared with baseline data using paired t tests. RESULTS: The location of the minimum of stroke work was observed at a delay of 10% (soon after aortic valve opening), resulting in a median of 43% reduction in stroke work compared with baseline. Maximum stroke work occurred at a median delay of 70% with a median stroke work increase of 11% above baseline. Left ventricular volume unloading expressed by end-diastolic volume was most pronounced for copulsation (delay 0%). CONCLUSIONS: The timing of pump ejection in synchronized mode yields control over left ventricular energetics and can be a method to achieve gradual reloading of a recoverable left ventricle. The traditionally suggested counterpulsation is not optimal in ventriculo-aortic cannulation when maximum unloading is desired.

Intravascular ultrasound-guided creation of re-entry sites to improve intermittent claudication in patients with aortic dissection

PURPOSE: To report percutaneous fenestration of aortic dissection flaps to relieve distal ischemia using a novel intravascular ultrasound (IVUS)-guided fenestration device. CASE REPORTS: Two men (47 and 62 years of age) with aortic dissection and intermittent claudication had percutaneous ultrasound-guided fenestration performed under local anesthesia. Using an ipsilateral transfemoral approach, the intimal flap was punctured under real-time IVUS guidance using a needle-catheter combination through which a guidewire was placed across the dissection flap into the false lumen. The fenestration was achieved using balloon catheters of increasing diameter introduced over the guidewire. Stenting of the re-entry was performed in 1 patient to equalize pressure across the dissection membrane in both lumens. The procedures were performed successfully and without complications. In both patients, ankle-brachial indexes improved from 0.76 to 1.07 and from 0.8 to 1.1, respectively. Both patients were without claudication at the 3- and 6-month follow-up examination. CONCLUSION: Percutaneous intravascular ultrasound-guided fenestration and stenting at the level of the iliac artery in aortic dissection patients with claudication is a technically feasible and safe procedure and relieves symptoms.

Lordoplasty: report on early results with a new technique for the treatment of vertebral compression fractures to restore the lordosis

Cement augmentation using PMMA cement is known as an efficient treatment for osteoporotic vertebral compression fractures with a rapid release of pain in most patients and prevention of an ongoing kyphotic deformity of the vertebrae treated. However, after a vertebroplasty there is no chance to restore vertebral height. Using the technique of kyphoplasty a certain restoration of vertebral body height can be achieved. But there is a limitation of recovery due to loss of correction when deflating the kyphoplastic ballon and before injecting the cement. In addition, the instruments used are quite expensive. Lordoplasty is another technique to restore kyphosis by indirect fracture reduction as it is used with an internal fixateur. The fractured and the adjacent vertebrae are instrumented with bone cannulas bipediculary and the adjacent vertebrae are augmentated with cement. After curing of the cement the fractured vertebra is reduced by applying a lordotic moment via the cannulas. While maintaining the pretension the fractured vertebra is reinforced. We performed a prospective trial of 26 patients with a lordoplastic procedure. There was a pain relief of about 87% and a significant decrease in VAS value from 7.3 to 1.9. Due to lordoplasty there was a significant and permanent correction in vertebral and segmental kyphotic angle about 15.2 degrees and 10.0 degrees , respectively and also a significant restoration in anterior and mid vertebral height. Lordoplasty is a minimal invasive technique to restore vertebral body height. An immediate relief of pain is achieved in most patients. The procedure is safe and cost effective.

Prediction of hip fracture risk by quantitative ultrasound in more than 7000 Swiss women > or =70 years of age: comparison of three technologically different bone ultrasound devices in the SEMOF study

To compare the prediction of hip fracture risk of several bone ultrasounds (QUS), 7062 Swiss women > or =70 years of age were measured with three QUSs (two of the heel, one of the phalanges). Heel QUSs were both predictive of hip fracture risk, whereas the phalanges QUS was not. INTRODUCTION: As the number of hip fracture is expected to increase during these next decades, it is important to develop strategies to detect subjects at risk. Quantitative bone ultrasound (QUS), an ionizing radiation-free method, which is transportable, could be interesting for this purpose. MATERIALS AND METHODS: The Swiss Evaluation of the Methods of Measurement of Osteoporotic Fracture Risk (SEMOF) study is a multicenter cohort study, which compared three QUSs for the assessment of hip fracture risk in a sample of 7609 elderly ambulatory women > or =70 years of age. Two QUSs measured the heel (Achilles+; GE-Lunar and Sahara; Hologic), and one measured the heel (DBM Sonic 1200; IGEA). The Cox proportional hazards regression was used to estimate the hazard of the first hip fracture, adjusted for age, BMI, and center, and the area under the ROC curves were calculated to compare the devices and their parameters. RESULTS: From the 7609 women who were included in the study, 7062 women 75.2 +/- 3.1 (SD) years of age were prospectively followed for 2.9 +/- 0.8 years. Eighty women reported a hip fracture. A decrease by 1 SD of the QUS variables corresponded to an increase of the hip fracture risk from 2.3 (95% CI, 1.7, 3.1) to 2.6 (95% CI, 1.9, 3.4) for the three variables of Achilles+ and from 2.2 (95% CI, 1.7, 3.0) to 2.4 (95% CI, 1.8, 3.2) for the three variables of Sahara. Risk gradients did not differ significantly among the variables of the two heel QUS devices. On the other hand, the phalanges QUS (DBM Sonic 1200) was not predictive of hip fracture risk, with an adjusted hazard risk of 1.2 (95% CI, 0.9, 1.5), even after reanalysis of the digitalized data and using different cut-off levels (1700 or 1570 m/s). CONCLUSIONS: In this elderly women population, heel QUS devices were both predictive of hip fracture risk, whereas the phalanges QUS device was not.

Safety of Active Implantable Devices during MRI Examinations: A Finite Element Analysis of an Implantable Pump

The goal of this study was to propose a general numerical analysis methodology to evaluate the magnetic resonance imaging (MRI)-safety of active implants. Numerical models based on the finite element (FE) technique were used to estimate if the normal operation of an active device was altered during MRI imaging. An active implanted pump was chosen to illustrate the method. A set of controlled experiments were proposed and performed to validate the numerical model. The calculated induced voltages in the important electronic components of the device showed dependence with the MRI field strength. For the MRI radiofrequency fields, significant induced voltages of up to 20 V were calculated for a 0.3T field-strength MRI. For the 1.5 and 3.0T MRIs, the calculated voltages were insignificant. On the other hand, induced voltages up to 11 V were calculated in the critical electronic components for the 3.0T MRI due to the gradient fields. Values obtained in this work reflect to the worst case situation which is virtually impossible to achieve in normal scanning situations. Since the calculated voltages may be removed by appropriate protection circuits, no critical problems affecting the normal operation of the pump were identified. This study showed that the proposed methodology helps the identification of the possible incompatibilities between active implants and MR imaging, and can be used to aid the design of critical electronic systems to ensure MRI-safety

Percutaneous left ventricular assist devices for treatment of patients with cardiogenic shock

PURPOSE OF REVIEW: This review will discuss the rationale and clinical utility of percutaneous left ventricular assist devices in the management of patients with cardiogenic shock. RECENT FINDINGS: Left ventricular assist devices maintain partial or total circulatory support in case of severe left ventricular failure. Currently, two percutaneous left ventricular assist devices are available for clinical use: the TandemHeart and the Impella Recover LP system. Compared with the intraaortic balloon pump, the TandemHeart has been shown to significantly reduce preload and to augment cardiac output. In a randomized comparison between the TandemHeart and intraaortic balloon pump support in patients with cardiogenic shock, the improved cardiac index afforded by the left ventricular assist device resulted in a more rapid decrease in serum lactate and improved renal function. There were, however, no significant differences with respect to 30-day mortality, and complications including limb ischemia and severe bleeding were more frequent with left ventricular assist devices than intraaortic balloon pump support. SUMMARY: The advent of percutaneous left ventricular assist devices constitutes an important advance in the management of patients with severe cardiogenic shock and may serve as bridge to recovery or heart transplantation in carefully selected patients. While improvement of hemodynamic parameters appears promising, it remains to be determined whether this benefit translates into improved clinical outcome.