NEUROLOGIC COMPLICATIONS OF TRANSAXILLARY ACCESS IN TAVR - A CASE OF POSTPROCEDURAL ULNAR AND MEDIAN NERVE INJURY

Background: Peripheral nerve injuries secondary to endovascular procedures are relatively rare but cause significant functional impairment. With transaortic valve replacement (TAVR), these injuries more commonly occur during axillary access compared to femoral and radial access (due to its proximity to brachial plexus). While hematoma and pseudoaneurysm formation are the more common complications, nerve injury may occur secondary to compression or direct needle puncture. Case: A 76-year-old male with severe aortic stenosis underwent two failed TAVR attempts due to poor access. Initial attempts at femoral access and transcaval access were aborted due to existing abdominal aortic endograft. Further attempts via carotid access were aborted due to stenosis. An attempt at left axillary access was then performed and TAVR was successful. Postoperatively (day 0), the patient developed left upper extremity (LUE) numbness over the 4th and 5th digits, medial palm, and dorsum of the hand with weakness when holding objects. Our neurological evaluation identified a total ulnar nerve (UN) and partial median nerve (MN) injury. Decision-making: Transaxillary access for TAVR is a disfavored approach due to the better outcomes when performed with other access sites. After out identification of a postprocedural nerve injury, we ordered a LUE arterial duplex ultrasound (US) and CT angiogram which excluded hematoma or pseudoaneurysm formation. US of the left brachial plexus revealed questionable edematous change at the take-off of the left UN and MN. Patient’s symptoms did not improve postoperatively until his discharge from the hospital (day 3) and an outpatient nerve conduction study was scheduled. Conclusion: We report a rare case of proximal UN and MN injury in a patient who underwent transaxillary TAVR due to the lack of alternative access. Prompt evaluation to rule-out vascular mechanism of injury in this patient was critical as early intervention results reduce further morbidity. With symptoms of motor and sensory brachial plexopathy and concerning imaging findings, the patient was scheduled for outpatient follow-up

Reorganization of columnar architecture in the growing visual cortex

Many cortical areas increase in size considerably during postnatal development, progressively displacing neuronal cell bodies from each other. At present, little is known about how cortical growth affects the development of neuronal circuits. Here, in acute and chronic experiments, we study the layout of ocular dominance (OD) columns in cat primary visual cortex (V1) during a period of substantial postnatal growth. We find that despite a considerable size increase of V1, the spacing between columns is largely preserved. In contrast, their spatial arrangement changes systematically over this period. While in young animals columns are more band-like, layouts become more isotropic in mature animals. We propose a novel mechanism of growth-induced reorganization that is based on the `zigzag instability', a dynamical instability observed in several inanimate pattern forming systems. We argue that this mechanism is inherent to a wide class of models for the activity-dependent formation of OD columns. Analyzing one member of this class, the Elastic Network model, we show that this mechanism can account for the preservation of column spacing and the specific mode of reorganization of OD columns that we observe. We conclude that neurons systematically shift their selectivities during normal development and that this reorganization is induced by the cortical expansion during growth. Our work suggests that cortical circuits remain plastic for an extended period in development in order to facilitate the modification of neuronal circuits to adjust for cortical growth.Comment: 8+13 pages, 4+8 figures, paper + supplementary materia

Disparate Rates of Molecular Evolution in Cospeciating Hosts and Parasites

DNA sequences for the gene encoding mitochondrial cytochrome oxidase I in a group of rodents (pocket gophers) and their ectoparasites (chewing lice) provide evidence for cospeciation and reveal different rates of molecular evolution in the hosts and their parasites. The overall rate of nucleotide substitution (both silent and replacement changes) is approximately three times higher in lice, and the rate of synonymous substitution (based on analysis of fourfold degenerate sites) is approximately an order of magnitude greater in lice. The difference in synonymous substitution rate between lice and gophers correlates with a difference of similar magnitude in generation times

Molecular dissection of the migrating posterior lateral line primordium during early development in zebrafish

<p>Abstract</p> <p>Background</p> <p>Development of the posterior lateral line (PLL) system in zebrafish involves cell migration, proliferation and differentiation of mechanosensory cells. The PLL forms when cranial placodal cells delaminate and become a coherent, migratory primordium that traverses the length of the fish to form this sensory system. As it migrates, the primordium deposits groups of cells called neuromasts, the specialized organs that contain the mechanosensory hair cells. Therefore the primordium provides both a model for studying collective directional cell migration and the differentiation of sensory cells from multipotent progenitor cells.</p> <p>Results</p> <p>Through the combined use of transgenic fish, Fluorescence Activated Cell Sorting and microarray analysis we identified a repertoire of key genes expressed in the migrating primordium and in differentiated neuromasts. We validated the specific expression in the primordium of a subset of the identified sequences by quantitative RT-PCR, and by <it>in situ </it>hybridization. We also show that interfering with the function of two genes, <it>f11r </it>and <it>cd9b</it>, defects in primordium migration are induced. Finally, pathway construction revealed functional relationships among the genes enriched in the migrating cell population.</p> <p>Conclusions</p> <p>Our results demonstrate that this is a robust approach to globally analyze tissue-specific expression and we predict that many of the genes identified in this study will show critical functions in developmental events involving collective cell migration and possibly in pathological situations such as tumor metastasis.</p

Procedural and Mid-Term Outcomes of Coronary Protection During Transcatheter Aortic Valve Replacement in Patients at Risk of Coronary Occlusion: Insight From a Single-Centre Retrospective Analysis

BACKGROUND: Detailed procedural analysis and long-term data is limited for coronary protection (CP) during transcatheter aortic valve replacement (TAVR) for patients with high anatomical risk for coronary occlusion (CO). We aim to assess the procedural and mid-term outcomes of CP during TAVR. METHODS: We retrospectively analyzed patients who underwent TAVR at Henry Ford Hospital, USA from January 2015 to August 2019 and identified those considered at risk of CO and underwent pre-emptive CP with or without subsequent chimney stenting (i.e. coronary stenting with intentional protrusion into the aorta). Procedural features, immediate and mid-term clinical outcomes were reviewed. RESULTS: Twenty-five out of 1166 (2.1%) patients underwent TAVR with CP, including 10 (40%) valve-in-valve procedures. Twenty-eight coronary arteries (Left: n = 11, Right: n = 11; Left + Right: n = 3) were protected. Eleven coronaries (39.3%) were electively chimney -stented due to angiographic evidence of coronary impingement (63.6%), tactile resistance while withdrawing stent (27.3%) and electrocardiogram change (9.1%). Twenty-four patients (24/25, 96%) had successful TAVR without CO. Procedure-related complications included stent-balloon entrapment (n = 1), stent entrapment (n = 1) and occlusive distal stent edge dissection (n = 1). After a mean follow-up of 19.1 months, there was 1 cardiac death but no target vessel re-intervention or myocardial infarction. CONCLUSIONS: Our study found that angiographic evidence of coronary impingement (63.6%) was the most common reason for stent deployment during TAVR with CP. The mid-term clinical outcome of CP with TAVR was favorable

INITIAL EXPERIENCE WITH LITHOTRIPSY FOR MITRAL BALLOON VALVULOPLASTY

Background: Mitral annular calcification (MAC) causes degeneration of the mitral valve function. Since these patients are poor surgical candidates, options are limited to percutaneous solutions. Use of balloon lithotripsy (BL) to augment mitral balloon valvuloplasty (MBV) is a novel technique for treatment of MAC-related mitral stenosis (MS). Methods: Single-center retrospective review of 35 consecutive MBV for MAC cases at Henry Ford from 3/2013 to 4/2021. Outcome variables are reported as median and interquartile ranges (IQR). Chi-squared and Wilcoxon-signed rank tests were used to compare categorical and continuous variables respectively using 95% confidence intervals for statistical significance. Procedural success was defined as a final mitral valve area ≥1.5 cm2 or ≥50% reduction in gradient. Results: Of 35 MBV cases done for MAC, 5 utilized lithotripsy balloons to augment valvuloplasty results (Table). Mean baseline gradients were similar and right ventricular systolic pressures trended higher for BL cases. Cases utilizing lithotripsy were longer and utilized more fluoroscopy time but the final invasive gradient trended lower (non-BL 7mmHg [4, 9] vs. BL 1 mmHg [0,5] p=0.113), therefore, higher rates of procedural success were seen (non-BL 47% vs. BL 80%, p=0.2). Survival analysis was hampered due to loss of follow-up in the BL group. Conclusion: BL appears to augment immediate valvuloplasty results. Further studies regarding the durable impact of balloon lithotripsy on MBV are warranted