Current Issues and Recent Advances in Pacemaker Therapy

Patients with implanted pacemakers or defibrillators are frequently encountered in various healthcare settings. As these devices may be responsible for, or contribute to a variety of clinically significant issues, familiarity with their function and potential complications facilitates patient management. This book reviews several clinically relevant issues and recent advances of pacemaker therapy: implantation, device follow-up and management of complications. Innovations and research on the frontiers of this technology are also discussed as they may have wider utilization in the future. The book should provide useful information for clinicians involved in the management of patients with implanted antiarrhythmia devices and researchers working in the field of cardiac implants

The Development and Implementation of Evidence-Based Preanesthesia Assessment Tools for LVAD Patients Undergoing Non-Cardiac Procedures

Abstract A university-affiliated tertiary medical center with a newly developed Advanced Heart Failure and Mechanical Circulatory Support program identified the need to implement a more systematic approach to the preanesthesia assessment process for patients with a Left Ventricular Assist Device (LVAD) undergoing noncardiac procedures and standardized guidelines to determine the best blood pressure monitoring system for patients with an LVAD during these noncardiac procedures. A multidisciplinary panel of clinical experts developed an LVAD Preanesthesia Toolkit using standard recommendations identified via evidence-based literature and expert opinion. The Toolkit included an LVAD Preanesthesia Assessment (VaPA) tool and an LVAD Blood Pressure Monitoring Decision Tree. The Toolkit initiative utilized a checklist to promote safety and enhance access to LVAD-specific resource tools for anesthesia providers. An online education module outlining the details of the initiative was distributed to targeted users prior to a pilot implementation of the VaPA tool into clinical practice. Data collection concerning education dissemination revealed that 27.2% of anesthesia providers had reviewed and verbalized their understanding of the initiative. An analysis of the effectiveness of the VaPA tool was conducted in a 5-month retrospective review of electronic health records for LVAD patients undergoing noncardiac procedures. Outcome data revealed 100% accuracy in preanesthesia assessment documentation. Results indicated improved consistencies in documenting the LVAD specific components of the preanesthesia assessment

Instrumentation biomédicale et étude des applications sur des effets de champs magnétiques

This thesis has the objective to determine the effect produced by weak magnetic field stimulation on the following types of cell cultures: Entamoeba histolytica, Entamoeba invadens, human lymphocyte, and HEK- 293T.Changes in cell’sproliferation and longevity without affecting their viability are thus studied. We intend to understand the effect produced by the magnetic field and gadolinium in the different levels of cell organization (organelle, macro molecules, and chemical reactions).We are mainly interested in asserting the behavior of cells in a controlled manner, for example when applying oscillating magnetic fields at different frequencies and time intervals as well as the addition of certain concentrations of super-paramagnetic fluid in the growing medium. Here I present effects on the cell motility of Entamoeba invadens cell cultures and the change in the natural cell behavior, such as controlled agglutination, cell movement velocity, membrane structural form. I also present the effects and dynamic responses on the growth of Entamoeba cells by applying an oscillating magnetic field in specific audio frequencies such as 100 Hz, 800 Hz, 1500 Hz, and 2500Hz, at six minutes time periodic intervals.La dynamique de culture de cellules peut être modifié lors de l'application de champs magnétiques fluctuants afin d’stimuler la prolifération et longévité de cellules mais sans affecter leur viabilité. Cela se fait avec les conditions expérimentales et paramètres optimales. Dans cette thèse je montre l’étude à différents types de cellules tels que l’Entamoeva histolitica et invadens, les lynphosites humains et l’HEK-293E pour obtenir quelques paramètres importants qui puissent nous permettre à mieux comprendre les effets subis par elles quand un champ magnétique est appliqué. L’objective de mon travail est d’étudier la culture de cellules et sa dynamique quand elle ressent un champ magnétique d’une certaine intensité, a une certaine fréquence, le nombre de fois d’application et les effets que le champ peut l’induire. Je considère aussi la concentration de fluides paramagnétiques dans le milieu de culture chargé d’amplifier l’effet de stimulation. Finalement, je parlerais de la conception d’une instrumentationcapable de pourvoir aux cellules les meilleures conditions de reproduction telle que la température, espace, distribution efficace du champ magnétique et sa forme de radiation. La conception d’une nouvelle instrumentation qui puisse tenir en compte des nouvelles variables est aussi traitée. Cette même instrumentation s’est révélée très robuste pour être aussi appliquée dans d’autres sujets d’étude biomédicale avec des faibles modifications. Son utilisation en diagnostique de dislocation de la hanche, la mesure de fréquences dans la région gastroesophagea pour étudier la dynamique du métabolisme

Functional MRI of rat kidney using BOLD & ASL techniques

Noninvasive functional magnetic resonance imaging (fMRI) methods may provide new ways to detect and track renal hemodynamic changes in-vivo. In this thesis, two fMRI methods were correlated with simultaneous invasive hemodynamic measurements. A particular goal of this thesis was to measure the relative contributions of oxygenation and perfusion changes to changes in the relaxation rate, T2*. Also, an MRI compatible motion detector was built and along with the invasive probes was interfaced to a data acquisition system for use during scanning. Drug-induced changes in renal oxygenation and blood flow were measured by BOLD- & ASL-MRI noninvasively, while a dual oxygenation/perfusion optical-probe was used for the invasive measurements. Six sets of results were obtained. Values of T2*, LDF and pO2 correlated in four of the data sets while the other two were discrepant. BOLD images were of high quality while ASL perfusion maps were of inadequate spatial resolution and poor quality

Evaluation of a Video-Based Left Ventricular Assist Device Education Program for Certified Registered Nurse Anesthetists and Student Registered Nurse Anesthetists

Background: Video-based educational programs have been proven as a more effective means of instruction than traditional lecture and paper-based formats. Therefore, a video-based left ventricular assist device (LVAD) program was developed to address an identified knowledge gap for the NorthShore University HealthSystem (NSUHS) Certified Registered Nurse Anesthetists (CRNA) and Student Registered Nurse Anesthetists (SRNA). Objectives: The purpose of this quality improvement project (QIP) was to pilot a newly developed educational video intervention and evaluate the CRNAs’ and SRNAs’ pre- and postintervention knowledge difference of the LVAD and the LVAD patient population. Methods: The sample consisted of CRNAs and SRNAs from NSUHS and the NSUHS School of Nurse Anesthesia. Pre- and post-tests were used and uploaded to Google Forms to maintain anonymity and SPSS was used for data analysis. Results: The sample consisted of 13 CRNAs and SRNAs. Pre-test scores were found to be less than adequate (M=5.46, SD=1.71). Post-test scores after the educational video intervention did improve (M=6.46, SD=1.90), however, the results were statistically not significant (M=1.00, SD=1.87, -0.13 to 2.13 CI 95%, p=0.078). The Kuder-Richardson-20 (KR20) reliability coefficient for post-test scores was 0.518, which demonstrated adequate internal consistency for the post-test. Conclusion: The results demonstrated that the LVAD educational video intervention improved post-test scores when compared to pre-test scores. Although the results were statistically not significant and further large-sample studies are needed, this educational video intervention can be a useful tool to bridge the NSUHS CRNAs and SRNAs knowledge gap of LVADs and the LVAD patient population

Spacelab J experiment descriptions

Brief descriptions of the experiment investigations for the Spacelab J Mission which was launched from the Kennedy Space Center aboard the Endeavour in Sept. 1992 are presented. Experiments cover the following: semiconductor crystals; single crystals; superconducting composite materials; crystal growth; bubble behavior in weightlessness; microgravity environment; health monitoring of Payload Specialists; cultured plant cells; effect of low gravity on calcium metabolism and bone formation; and circadian rhythm

Neurophysiological effects of ischaemia

Spinal cord injury (SCI) and paralysis remains a tragic complication of thoraco-abdominal aortic aneurysm (TAAA) surgery, despite advances in surgical and medical management. A survey of vascular anaesthetists showed availability of intra-operative spinal cord monitoring to detect an injury and subsequently guide remedial interventions, is variable across the United Kingdom and Ireland, despite clear evidence of its benefit. This research sought to explore the potential benefits of transcranial magnetic stimulation (TMS) and near infrared spectroscopy (NIRS) as alternative, more accessible monitors of ischaemic SCI. TAAA surgery has several nuances that required greater investigation if TMS was to be utilised in theatre. Firstly, the motor evoked potentials (MEPs) of peripheral vascular disease (PVD) patients were characterised. PVD is the primary pathology underlying TAAA and the MEPs of this cohort of patients showed no difference beyond that which would accountable by aging compared to healthy, younger controls. Also, it was demonstrated that over an hour of repeated single-pulse TMS, a time-frame similar to when the spinal cord is at greatest risk intra-operatively and a need for intense monitoring, the variability of the MEPs was no different to controls. A second feature of TAAA surgery is the need to render the surgical field bloodless, thus providing a clear operative space for the surgeons to work in. This is achieved using arterial clamps, the unintended consequence of which is an ischaemic nerve block (INB). An INB has been used as a research tool to initiate changes in cortical excitability. Deafferentation of distal limb structures and subsequent disinhibition of the motor cortical output to non-ischaemic muscles ipsilateral to the INB, manifested as increased MEPs. Through the use of a novel, low pressure INB applied to the lower limb, an increase in MEP amplitude in muscles proximal to the INB occurred. It was further shown that this increase in cortical excitability extended to the contralateral legs muscles and to arm muscles. Simultaneous recordings of somatosensory evoked potentials (SSEP) from stimulation of the tibial nerve, also distal to the INB, demonstrated a reduction in SSEP amplitude but not a complete deafferentation as previously assumed. Investigations into the mechanisms underlying these finding was then performed. Using quantitative sensory testing whilst an INB was performed, the loss of Aβ and Aδ indicated the deafferentation required to initiate changes in motor cortical excitability. The preservation of C-fibre function could account for the unexpected finding where participants with exaggerated punctate sensation had greater increases in MEPs and possible cortical excitability. Paired-pulse TMS paradigms explored the potential neuronal networks responsible for the increase in MEPs of the contralateral muscles. A reduction in interhemispheric inhibition was seen from the deafferented motor cortex to the intact motor cortex, whilst no change in intrahemispheric pathways was seen. The final chapter of this thesis explores the use of TMS and NIRS under surgical conditions. Despite numerous obstacles to patient recruitment, not withstanding a pandemic, a case series is presented with meaningful data which can be used to guide future study. Under the correct anaesthetic regimen, TMS induced MEPs can be recorded. The limited sample size was unable to determine if changes in cortical excitability occur in these conditions during surgery utilising a thigh INB however. In the second clinical investigation, NIRS was used to measure paraspinal muscle oxygen saturations levels (rO2), believed to correlate with intra-spinal oxygenation. This was performed alongside traditional intraoperative neuromonitoring of spinal cord with transcranial electrical stimulation (TES) MEPs. Paraspinal rO2 appeared to follow changes in the haemodynamic status of the patients, where a low rO2 would reflect a low blood pressure. One patient experienced a paraparesis, with a recoverable reduction in MEP amplitude and paraspinal rO2. Another patient who later died without clinical confirmation of paralysis, had a precipitous and permanent reduction in both MEPs and rO2, likely reflecting a SCI. A third patient where a decrease in MEPs and paraspinal rO2 was seen had remedial interventions initiated to prevent a possible SCI, which resulted in a return of both measures close to baseline. Future work should look to explore the changes in cortical excitability secondary to iatrogenic limb ischaemic during TAAA surgery and how this impacts TMS-induced MEP characteristics and their interpretation in detecting a SCI. It should also explore their use alongside NIRS to detect both intra-operative and post-operative SCI and to guide their management.Open Acces

Determinants of Doppler Flow Velocity Waveforms in the Uteroplacental and Umbilical Arteries

Non-invasive assessment of blood flow in the uteroplacental and umbilical arteries using Doppler velocimetry is a promising technique for the identification of fetal compromise and seems likely to be introduced widely into clinical practice. Nevertheless, many problems remain to be resolved regarding the potential use of Doppler in obstetrics. These problems arise in part from a lack of understanding of which indices are most appropriate for describing waveforms and of the factors determining abnormal waveforms. In a cross sectional study of 356 normal and complicated pregnancies the three most commonly used indices, the pulsatility index, resistance index and systolic/diastolic ratio were found to be highly correlated with each other and could be used interchangeably unless absence of end diastolic velocities was observed. The association between advancing gestational age and umbilical artery waveform indices, showing reduced placental vascular resistance, was confirmed although no such association was seen in uteroplacental patterns. Placental vascular pathology has been implicated in the production of abnormal uteroplacental and umbilical artery Doppler waveforms. It has been postulated that Doppler studies in mid-trimester might identify pregnancies at risk of later complications. Elevated maternal serum alphafetoprotein (AFP) in pregnancies with normally formed fetuses is also known to be associated with a high risk of perinatal complications and a placental pathology has recently been suggested as underlying this. To determine if Doppler might identify such a lesion, 40 patients with unexplained elevation of maternal serum AFP underwent Doppler studies in the mid trimester. Although there was a significant difference in the incidence of later complications from a matched group of control patients there was no difference from controls in Doppler indices from the uteroplacental or umbilical circulations. Consequently the hypothesis that Doppler might identify a placental lesion associated with later complications is rejected. Furthermore, despite a 40% incidence of complications in the elevated AFP group the values obtained were within previously published normal ranges for the gestation of study and the findings do not support a role for Doppler in screening in mid trimester for later complications. Abnormal waveforms have been reported in pregnancies in which the fetus is small-for-dates and in those complicated by hypertension but few controlled studies have been performed to determine the role played by these conditions in producing changes in waveform indices. A controlled study was performed to determine if uteroplacental and umbilical artery waveforms are altered in pregnancies in which the fetus is small-for-dates. Waveforms were obtained in 32 such pregnancies. No difference in uteroplacental waveform indices was identified. In contrast, the indices from the umbilical artery were significantly higher, though not necessarily abnormal, compared with matched controls. These data suggest that haemodynamic changes occur in such fetuses even when, as determined by Doppler, uteroplacental perfusion is maintained. It is known that in some small-for-dates fetuses blood viscosity is increased. From Pouseille's equation it is known that blood flow is dependent on blood viscosity and the need for intra-uterine intravascular transfusion in some cases of rhesus disease provided the opportunity to determine if an increase in blood viscosity following transfusion is associated with an increase in Doppler indices of resistance. Twenty women underwent a total of 35 percutaneous umbilical blood sampling procedures and on 22 occasions intra-vascular transfusion was indicated from the results obtained. The systolic/diastolic ratio was measured immediately before and 1 hour after sampling or, if performed, transfusion. A reduction in the systolic/diastolic ratio was seen whether transfusion was performed or not indicating that a reduction in resistance to blood flow occurred. This surprising finding suggests that umbilical cord puncture itself may result in the release of vasodilator substances and this must be investigated in further studies. To determine if pregnancy induced hypertension (PIH) and absolute levels of blood pressure influenced waveforms, a group of 48 untreated carefully defined patients were compared with an individually matched control group. In the hypertensive patients the Doppler indices of vascular resistance in the uteroplacental vessels were significantly higher than controls. In contrast, the results from the umbilical artery analysis showed increased resistance, reflected in higher values for waveform indices, only when significant proteinuria was present