Ketamine Sedation Facilitates Asleep DBS: a multicenter retrospective study

Deep brain stimulation (DBS) is commonly and safely performed for selective Parkinson's disease patients. Many centers perform DBS lead positioning exclusively under local anesthesia, to allow for brain microelectrode recordings (MER) and testing of stimulation-related therapeutic and side effects. These measures enable physiological identification of the DBS targets based on electrophysiological properties like firing rates and patterns, optimization of lead placement accuracy, and intra-operative evaluation of therapeutic window. Nevertheless, due to the challenges of awake surgery, some centers use sedation or general anesthesia, despite the distortion of discharge properties, and potential impact on clinical outcomes. Thus, there is a need for a novel anesthesia regimen that enables sedation without compromising intra-operative monitoring. This study investigates the use of low-dose ketamine for conscious sedation during lead positioning in subthalamic nucleus (STN) DBS for Parkinson's disease patients. Three anesthetic regimens were retrospectively compared in 38 surgeries across three DBS centers: 1) Interleaved propofol-ketamine (PK), 2) Interleaved propofol-awake (PA), and 3) Fully awake (AA). All anesthesia regimens achieved satisfactory MER. Automatic detection of STN borders and subdomains using a Hidden Markov Model was similar between the groups. Patients' symptoms and cooperation during stimulation testing in the ketamine group was not altered. No major adverse effects were reported in the different anesthesia protocols. These results support the use of low-dose ketamine as a novel alternative for the existing DBS anesthesia regimens, optimizing patient's experience while preserving lead placement accuracy. A prospective study should be performed to confirm these findings.

Electrocardio Panorama: Synthesizing New ECG views with Self-supervision

Multi-lead electrocardiogram (ECG) provides clinical information of heartbeats from several fixed viewpoints determined by the lead positioning. However, it is often not satisfactory to visualize ECG signals in these fixed and limited views, as some clinically useful information is represented only from a few specific ECG viewpoints. For the first time, we propose a new concept, Electrocardio Panorama, which allows visualizing ECG signals from any queried viewpoints. To build Electrocardio Panorama, we assume that an underlying electrocardio field exists, representing locations, magnitudes, and directions of ECG signals. We present a Neural electrocardio field Network (Nef-Net), which first predicts the electrocardio field representation by using a sparse set of one or few input ECG views and then synthesizes Electrocardio Panorama based on the predicted representations. Specially, to better disentangle electrocardio field information from viewpoint biases, a new Angular Encoding is proposed to process viewpoint angles. Also, we propose a self-supervised learning approach called Standin Learning, which helps model the electrocardio field without direct supervision. Further, with very few modifications, Nef-Net can synthesize ECG signals from scratch. Experiments verify that our Nef-Net performs well on Electrocardio Panorama synthesis, and outperforms the previous work on the auxiliary tasks (ECG view transformation and ECG synthesis from scratch). The codes and the division labels of cardiac cycles and ECG deflections on Tianchi ECG and PTB datasets are available at https://github.com/WhatAShot/Electrocardio-Panorama.

Imaging of Auditory Brain Stem Implants

Auditory brain stem implants are infrequently encountered neuroprosthetic devices used for auditory rehabilitation in deaf patients with pathology between the cochlea and cochlear nuclei who would not benefit from cochlear implantation. This article reviews the device, the relevant anatomy, audiologic performance, operative approaches, and conditions in which auditory brain stem implants are indicated. The imaging appearance of auditory brain stem implants, including optimal lead positioning, and imaging safety considerations of the device are also discussed. Knowledge of the device can assist the radiologist in detecting postoperative complications and component malpositioning and in providing safe and effective imaging practices in patients with indwelling auditory brain stem implants.Learning Objective: To describe the auditory brain stem implant device, identify optimal lead positioning, and list indications for auditory brain stem implant placement.

P750 Dynamics of tricuspid regurgitation after right ventricular lead implantation

Placement of ICDs, permanent pacemakers, and biventricular devices is performed under fluoroscopic guidance. Implantable device leads can cause tricuspid regurgitation (TR) when they interfere with leaflet motion. In the past, we had the experience of 2 cases with RV lead who had severe TR; one had lead repositioning and the other needed surgery. Aim: Evaluation of TR after right ventricular (RV) permanent lead implantation to check if echocardiographic guidance is needed for adequate lead positioning. Methods: Seventy six patients had trans-thoracic Doppler echocardiographic studies before and after implantation of permanent RV leads. Results: Before RV lead implantation 96% of patients had TR, grade 1 in 57 patients (75%), grade 2 in 12 (16%), grade 3 and 4 in 4 (5%). After RV lead implantation 44 patients with grade 1 TR remained with the same degree (77%) while in 2 (3.5%) TR progressed to grade 2, and in the remainder the TR disappeared. Most of the patients with grade 2 TR before RV lead implantation (75%) remained in grade 2 while 25% the grade decreased to grade 1. In all the patients with grade 3 and 4 TR pre-implantation, the severity of TR decreased by one grade. In 56 patients with non-CRT device implantations, 39 (70%) had grade I TR before procedure and in 28 (72%) of them TR grade did not change and 11(28%) TR grade progressed to grade 2 after implantation. Grade 2 TR before implantation in 8 patients (14%), the TR grade decreased in3 (37.5%) and did not change in the others. In 3 (5.4%) patients with grade 3 and 4 TR before procedure, the TR decreased after procedure. Conclusions: Implantation of permanent RV leads did not worsen TR grade.