Anatomic, histologic, and mechanical features of the right atrium: implications for leadless atrial pacemaker implantation

BACKGROUND

Leadless pacemakers (LPs) may mitigate the risk of lead failure and pocket infection related to conventional transvenous pacemakers. Atrial LPs are currently being investigated. However, the optimal and safest implant site is not known.

OBJECTIVES

We aimed to evaluate the right atrial (RA) anatomy and the adjacent structures using complementary analytic models [gross anatomy, cardiac magnetic resonance imaging (MRI), and computer simulation], to identify the optimal safest location to implant an atrial LP human.

METHODS AND RESULTS

Wall thickness and anatomic relationships of the RA were studied in 45 formalin-preserved human hearts. In vivo RA anatomy was assessed in 100 cardiac MRI scans. Finally, 3D collision modelling was undertaken assessing for mechanical device interaction. Three potential locations for an atrial LP were identified; the right atrial appendage (RAA) base, apex, and RA lateral wall. The RAA base had a wall thickness of 2.7 ± 1.6 mm, with a low incidence of collision in virtual implants. The anteromedial recess of the RAA apex had a wall thickness of only 1.3 ± 0.4 mm and minimal interaction in the collision modelling. The RA lateral wall thickness was 2.6 ± 0.9 mm but is in close proximity to the phrenic nerve and sinoatrial artery.

CONCLUSIONS

Based on anatomical review and 3D modelling, the best compromise for an atrial LP implantation may be the RAA base (low incidence of collision, relatively thick myocardial tissue, and without proximity to relevant epicardial structures); the anteromedial recess of the RAA apex and lateral wall are alternate sites. The mid-RAA, RA/superior vena cava junction, and septum appear to be sub-optimal fixation locations.

Cardiologist-Directed Sedation Management in Patients Undergoing Transvenous Lead Extraction: A Single-Centre Retrospective Analysis

BACKGROUND

The demand for transvenous lead extraction (TLE) has increased. In line with this, the safety of such procedures has also increased. Traditionally, TLE is performed under resource-intensive general anaesthesia. This study aims to evaluate the safety and outcomes of Cardiologist-lead deep sedation for TLE.

METHODS

We retrospectively analysed 328 TLE procedures performed under deep sedation from 2016 to 2019. TLE procedures were performed by experienced electrophysiologists. Sedation was administered by a specifically trained cardiologist (bolus midazolam/fentanyl and propofol infusion). Procedural sedation data including blood pressure, medication administration and sedation time were collected. Complications related to sedation and the operative component of the procedure were analysed retrospectively.

RESULTS

The sedation-associated complication rate during TLE was 22.0%. The most common complication (75% of complications) was hypotension requiring noradrenaline, followed by bradycardia requiring atropine (13% of complications). Additionally, the unplanned presence of an anaesthesiologist was needed in one case (0.3%). Deep sedation was achieved with midazolam (mean dose 42.9 ± 26.5 µg/kg), fentanyl (mean dose 0.4 ± 0.6 µg/kg) and propofol (mean dose 3.5 ± 1.2 mg/kg/h). There was no difference in medication dosage between those with a sedation-associated complication and those without. Sedation-associated complications appeared significantly more in patients with reduced LVEF (p = 0.01), renal impairment (p = 0.01) and a higher American Society of Anaesthesiologists (ASA) class (p = 0.01).

CONCLUSION

Deep sedation for TLE can be safely performed by a specifically trained cardiologist, with a transition to general anaesthesia required in only 0.3% of cases. We continue to recommend the on-call availability of an anaesthesiologist and cardiac surgeon in case of major complications.

Left bundle branch area pacing in congenital heart disease

AIMS

Left bundle branch area pacing (LBBAP) has been shown to be effective and safe. Limited data are available on LBBAP in the congenital heart disease (CHD) population. This study aims to describe the feasibility and safety of LBBAP in CHD patients compared with non-CHD patients.

METHODS AND RESULTS

This is a single-centre, non-randomized observational study recruiting consecutive patients with bradycardia indication. Demographic data, ECGs, imaging, and procedural data including lead parameters were recorded. A total of 39 patients were included: CHD group (n = 13) and non-CHD group (n = 26). Congenital heart disease patients were younger (55 ± 14.5 years vs. 73.2 ± 13.1, P < 0.001). Acute success was achieved in all CHD patients and 96% (25/26) of non-CHD patients. No complications were encountered in either group. The procedural time for CHD patients was comparable (96.4 ± 54 vs. 82.1 ± 37.9 min, P = 0.356). Sheath reshaping was required in 7 of 13 CHD patients but only in 1 of 26 non-CHD patients, reflecting the complex and distorted anatomy of the patients in this group. Lead parameters were similar in both groups; R wave (11 ± 7 mV vs. 11.5 ± 7.5, P = 0.881) and pacing threshold (0.6 ± 0.3 V vs. 0.7 ± 0.3, P = 0.392). Baseline QRS duration was longer in the CHD group (150 ± 28.2 vs. 118.6 ± 26.6 ms, P = 0.002). Despite a numerically greater reduction in QRS and a similar left ventricular activation time (65.9 ± 6.2 vs. 67 ± 16.8 ms, P = 0.840), the QRS remained longer in the CHD group (135.5 ± 22.4 vs. 106.9 ± 24.7 ms, P = 0.005).

CONCLUSION

Left bundle branch area pacing is feasible and safe in CHD patients as compared to that in non-CHD patients. Procedural and fluoroscopy times did not differ between both groups. Lead parameters were satisfactory and stable over a short-term follow-up.

Left Bundle Area Pacing for Tachycardia-Bradycardia Syndrome in a Patient With Dextrocardia

We present the case of an 81-year-old woman with a background of situs inversus with dextrocardia who was successfully treated for tachycardia-bradycardia syndrome with left bundle area pacing. This report describes how this approach can circumvent the limitations of other pacing approaches to optimize patient outcomes. (Level of Difficulty: Intermediate.)

746 VALIDITY OF THE CARER DIRECTED NEEDS ASSESSMENT IN DEMENTIA (CANDID) FOR USE IN ADVANCED STAGE DEMENTIA CARE

Introduction

End of life care for people dying of dementia and their carer/s is a growing area of importance. Unmet needs are coming amongst this group. A tool to identify the needs of this person-carer dyad is a necessary component for providing this care. The aim of this project was to determine the validity of a new tool, the CArer directed NeeDs assessment In Dementia (CANDID), which was developed for use in a randomised trial of end of life dementia care.

Method

Face validity of CANDID was assessed by an expert panel. A narrative review of the literature to evaluate existing tools available for assessing the needs of carers of people with advanced stage dementia was conducted. A sample of ten trial participants independently completed CANDID and the Carer Specific Needs Assessment Tool (CSNAT), which was selected as the reference tool based on the narrative review. The results from CANDID and CSNAT were compared to assess criterion validity. Participants also completed an evaluation survey to determine which tool they preferred, and why. Responses were compared qualitatively and quantitatively.

Results

CANDID has good face validity. There were insufficient participant numbers to establish criterion validity. The majority (n = 8) of participants preferred CANDID. Participants described a preference for a face to face tool with more specific questions.

Conclusion

Participant carers of people dying of dementia in this trial setting preferred a face to face evaluation of needs. Preliminary results from this study suggest that CANDID has face and content validity, and shows promise for criterion validity.

EXTH-59. POTENT, SELECTIVE, AND BRAIN PENETRANT INHIBITORS OF EXTRACELLULAR DOMAIN EGFR ONCOGENIC MUTANTS EXPRESSED IN GBM DEMONSTRATE EFFICACY IN AN INTRACRANIAL PATIENT DERIVED XENOGRAFT MODEL

EGFR mutations identified in glioblastomas (GBM) occur nearly exclusively at the allosteric extracellular domain (ECD) and constitutively activate oncogenic signaling. Despite wide success in treating tumors expressing EGFR catalytic site mutants, no drug has demonstrated clinical utility against tumors expressing the extracellular domain EGFR mutants. We demonstrate that the family of ECD mutations are not only co-expressed in GBM, but that they all activate the oncogene through a similar disulfide bond-mediated receptor dimerization mechanism. This dimerization occurs independent of ligands and renders the Locked-dimer (LoDi)-EGFR insensitive to agents that target the EGFR kinase domain mutants in NSCLC. The kinase conformation induced by these ECD mutations seen in glioblastomas is both oncogenic and altered from kinase domain mutations, thus necessitating a new approach to targeting. By screening against cells expressing LoDi-EGFR mutants, we have identified the first inhibitors that potently and selectively target LoDi-EGFR mutants versus both canonical active site oncogenic mutants and wild type EGFR. Through an optimization effort, we have identified a novel family of potent and selective LoDi-EGFR mutant inhibitors that effectively penetrate the blood brain barrier (BBB) following oral dosing in preclinical studies. A leading exemplar, BDTX-GBM-001, inhibits the 5 major LoDi-EGFR mutants expressed in GBM with antiproliferative potency of ~10 nM while showing favorable selectivity versus the human kinome. When dosed orally in the intracranial GBM6 patient derived xenograft model at 50, 30, and 15 mg/kg, a dose responsive decrease in tumor growth, as well as a statistically significant increase in survival, were observed. These data support the continued evaluation of rationally designed BBB penetrant inhibitors selectively targeting the common LoDi-EGFR mutants and enable the first chance to fully test the clinical hypothesis of EGFR driver mutants in GBM.

Benefit of Sequential Audit Cycles in Improving Management of Vitamin D Deficiency in the HIV Infected Paediatric Population

Aims Lifelong HIV infection has an unknown impact on bone health in children. In view of this, we aimed to improve management of vitamin D deficiency. Methods Three audits over 8 years (2009-2017) were performed with interventions introduced intermittently in an effort to improve vitamin D deficiency. The interventions included education, a change in vitamin D dose and brand to increase compliance and a shift to nursing led management. Results The most striking result was the eradication of patients with deficient vitamin D levels (<25nmol/L) in 2017. In 2009 and 2015, 15% and 9% were deficient. In the earlier two studies, only 15% had ‘sufficient’ (>50nmol) vitamin D levels. This increased to 71% in 2017. 10% of patients had levels greater than >120nmol/L, increasing risk of vitamin D toxicity. 67% of patients with insufficient vit D (25-50nmol/L) were prescribed a stat high dose vitamin D (120,000 IU) to help avoid adherence issues. Conclusions Sequential audits along with a shift to nurse led management were the most likely reasons for sustained improvement. Similar projects in all medical departments could improve clinical outcomes.

Relationships between cerebral autoregulation and markers of kidney and liver injury in neonatal encephalopathy and therapeutic hypothermia

OBJECTIVE

We studied whether cerebral blood pressure autoregulation and kidney and liver injuries are associated in neonatal encephalopathy (NE).

STUDY DESIGN

We monitored autoregulation of 75 newborns who received hypothermia for NE in the neonatal intensive care unit to identify the mean arterial blood pressure with optimized autoregulation (MAP_OPT). Autoregulation parameters and creatinine, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were analyzed using adjusted regression models.

RESULTS

Greater time with blood pressure within MAP_OPT during hypothermia was associated with lower creatinine in girls. Blood pressure below MAP_OPT related to higher ALT and AST during normothermia in all neonates and boys. The opposite occurred in rewarming when more time with blood pressure above MAP_OPT related to higher AST.

CONCLUSIONS

Blood pressures that optimize cerebral autoregulation may support the kidneys. Blood pressures below MAP_OPT and liver injury during normothermia are associated. The relationship between MAP_OPT and AST during rewarming requires further study.

Clinical and psychological moderators of the effect of mindfulness-based cognitive therapy on persistent pain in women treated for primary breast cancer - explorative analyses from a randomized controlled trial

BACKGROUND

Mindfulness-based intervention has been found efficacious in reducing persistent pain in women treated for breast cancer. Little, however, is known about possible moderators of the effect. We explored clinical and psychological moderators of the effect on pain intensity previously found in a randomized controlled trial of mindfulness-based cognitive therapy (MBCT) with women treated for breast cancer with persistent pain.

MATERIAL AND METHODS

A total of 129 women treated for breast cancer reporting persistent pain were randomized to MBCT or a wait-list control. The primary outcome of pain intensity (11-point numeric rating scale) was measured at baseline, post-intervention, three, and six months follow-up. Proposed clinical moderators included age, axillary lymph node dissection (ALND), radiotherapy, and endocrine treatment. Psychological moderators included psychological distress [the Hospital Anxiety and Depression Scale (HADS)], the adult attachment dimensions anxiety and avoidance [the Experiences in Close Relationships Short Form (the ECR-SF)], and alexithymia [the Toronto Alexithymia Scale (TAS-20)]. Multi-level models were used to test moderation effects over time, i.e. time × group × moderator.

RESULTS

Only attachment avoidance (p = 0.03, d = 0.36) emerged as a statistically significant moderator. Higher levels of attachment avoidance predicted a larger effect of MBCT in reducing pain intensity compared with lower levels attachment avoidance. None of the remaining psychological or clinical moderators reached statistical significance. However, based on the effect size, radiotherapy (p = 0.075, d = 0.49) was indicated as a possible clinical moderator of the effect, with radiotherapy being associated with a smaller effect of MBCT on pain intensity over time compared with no radiotherapy.

CONCLUSION

Attachment avoidance, and potentially radiotherapy, may be clinically relevant factors for identifying the patients who may benefit most from MBCT as a pain intervention. Due to the exploratory nature of the analyses, the results should be considered preliminary.

Guidance and Methodologies for Managing Digital Instrumentation and Control Obsolescence

New nuclear plant technology will rely heavily, if not exclusively, on digital equipment. Obsolescence of digital instrumentation and control (I&C) equipment is an inevitable part of plant technology life cycle for new and existing plants. Developing an overall strategic plan can mitigate some of the risks associated with obsolescence. Moreover, when developed as a part of an overall life cycle management plan (LCMP), a strategic obsolescence management approach can identify steps that can be taken at early stages of the technology life cycle to cope proactively with the obsolescence of equipment. Recent work within the advanced nuclear technology (ANT) program at the Electric Power Research Institute (EPRI) (O’Connor et al., 2014, “Advanced Nuclear Technology: Guidance and Methodologies for Managing Digital Instrumentation and Control Obsolescence,” EPRI, Palo Alto, CA, Product ID 3002002852) has developed guidance and methodologies for determining when digital obsolescence is likely to occur, the extent to which it can occur, the risks and impacts due to obsolescence, and strategies that can be used to minimize its effects, all in the context of system LCMP. Worksheets for assessing obsolescence risks and the applicability and limitations of management strategies were developed as a part of this work, and can be used to create or supplement a strategic obsolescence management plan.

The AgI/II family adhesin AspA is required for respiratory infection by Streptococcus pyogenes

Streptococcus pyogenes (GAS) is a human pathogen that causes pharyngitis and invasive diseases such as toxic shock syndrome and sepsis. The upper respiratory tract is the primary reservoir from which GAS can infect new hosts and cause disease. The factors involved in colonisation are incompletely known however. Previous evidence in oral streptococci has shown that the AgI/II family proteins are involved. We hypothesized that the AspA member of this family might be involved in GAS colonization. We describe a novel mouse model of GAS colonization of the nasopharynx and lower respiratory tract to elucidate these interactions. We used two clinical M serotypes expressing AspA, and their aspA gene deletant isogenic mutants in experiments using adherence assays to respiratory epithelium, macrophage phagocytosis and neutrophil killing assays and in vivo models of respiratory tract colonisation and infection. We demonstrated the requirement for AspA in colonization of the respiratory tract. AspA mutants were cleared from the respiratory tract and were deficient in adherence to epithelial cells, and susceptible to phagocytosis. Expression of AspA in the surrogate host Lactococcus lactis protected bacteria from phagocytosis. Our results suggest that AspA has an essential role in respiratory infection, and may function as a novel anti-phagocytic factor.