2550 results about "Artery" patented technology

A non-invasive physiological sensor system implemented as a smart watch or other wearable device includes an emitter for emitting light and a detector for collecting light after the light interacts with a tissue of a wearer. The system can measure light intensity at one or more radial distances to estimate attenuation parameter values that can be used to correct physiological parameter bias across subjects. In addition or alternatively, the system can determine whether a detector is positioned sufficiently proximate to an obstructing tissue (for example, an artery or vein) so as to cause inaccurate measurements by the detector.

The invention relates to the technical field of health status assessment, in particular to a cardiovascular disease layered early warning system, which is characterized in that blood vessel compliance and pulse wave velocity are extracted, arterial dilation capacity is measured, blood vessel elasticity is calculated, blood perfusion distribution is detected, and abnormal vasoconstriction is classified on the basis of a hemodynamic state and a heart electrical activity state; in combination with the thickness of the blood vessel wall and the blood vessel stenosis rate, the plaque deposition condition is analyzed, the arteriosclerosis score is calculated, the thrombosis tendency is detected, the local blood flow blocking degree is quantified, the isolation forest algorithm is adopted, the blood flow dynamic change is calculated, the heart rhythm abnormality is analyzed, the acute vascular occlusion probability is measured, and the sudden heart rhythm abnormality risk is evaluated. And based on a gradient boosting tree algorithm, screening high-risk cases, matching medical intervention measures, setting a risk buffer mechanism, adjusting an individual health management strategy, and optimizing a cardiovascular risk hierarchical early warning system.

The invention relates to the technical field of intelligent medical systems, and discloses a cerebral apoplexy onset risk assessment and reminding method and system.The method comprises the steps that continuous medical structured detection data are collected, and the data comprise carotid artery blood flow parameters, brain oxygen saturation, heart rate variability and metabolic indexes; inputting a bidirectional LSTM, a differential convolutional network, a wavelet residual network and a multi-layer perceptron to extract nonlinear features; constructing a neural function coupling structure diagram of four nodes of cerebral blood supply, oxygen supply, autonomous regulation and metabolic steady state; calculating inter-node time sequence offset correlation and a stable factor to obtain a coupling anomaly coefficient; and driving the embedded network by using a graph structure and a node feature input mechanism, and outputting a risk state assessment result. According to the method, the neural function coupling structure diagram is constructed and the mechanism is introduced to drive the embedded network, so that high-precision identification of the multi-system collaborative abnormal state and dynamic evaluation of the stroke risk level are realized.

Systems and methods are disclosed for simulation of occluded arteries and / or optimization of occlusion-based treatments. One method includes obtaining a patient-specific anatomic model of a patient's vasculature; obtaining an initial computational model of blood flow through the patient's vasculature based on the patient-specific anatomic model; obtaining a post-treatment computational model by modifying portions of the initial computational model based on an occlusion-based treatment; generating a pre-treatment blood flow characteristic using the initial computational model or computing a post-treatment blood flow using the post-treatment computational model; and outputting a representation of the pre-treatment blood flow characteristic or the post-treatment blood flow characteristic.

The invention provides an early-stage automatic identification method and system for acute kidney injury related to cardiac surgery, and relates to the technical field of physiological parameter detection. The method comprises the following steps: acquiring average arterial pressure, cardiac blood discharge volume, central venous pressure and blood oxygen saturation, regularly recording and extracting data of adjacent time points, calculating a variation range, screening a mutation region, judging whether a reference range is exceeded or not, analyzing a multi-parameter synchronous variation condition, and marking a hemodynamics abnormal state. According to the method, abnormal changes of hemodynamics and urine metabolism are accurately recognized through real-time monitoring and multi-parameter analysis, the urine flow rate and the metabolite excretion rate are combined, misjudgment of a single index is avoided, the fineness of renal function change analysis is improved, the high-risk time period is accurately positioned through time cross comparison, the diagnosis accuracy is improved, and the diagnosis accuracy is improved. Trend analysis and risk grade division enable the change of the illness state to be more visual, and a real-time early warning system effectively monitors the fluctuation trend, optimizes clinical management and improves the timeliness of medical response.

The invention discloses an embolism part for peripheral arteriovenous vessels, the embolism part comprises an anchoring part and a blocking part fixedly connected with the anchoring part, the blocking part adopts polyurethane shape memory foam, the expansion rate of the polyurethane shape memory foam is 50-100 times, and a preparation method of the polyurethane shape memory foam comprises the following steps: step 1, preparing a polyurethane shape memory foam material; the preparation method comprises the following steps: preparing a polyurethane acrylate prepolymer from macromolecular polyol, diisocyanate, a chain extender containing disulfide bonds, other micromolecular chain extenders and an acrylate end-capping reagent; and 2, uniformly mixing the polyurethane acrylate prepolymer, a foaming agent, a foaming promoter and a photoinitiator to obtain a foaming solution, and sequentially carrying out light curing and foaming on the foaming solution to obtain the polyurethane shape memory foam. According to the embolism part, the polyurethane shape memory foam is adopted as the blocking part, the blocking part applies radial acting force to the wall of the blood vessel all the time based on the expansion trend of the blocking part, and the blocking part and the anchoring part jointly act and can be stably maintained in the blood vessel.

The invention relates to the technical field of image analysis, in particular to a three-dimensional hepatic duct, hepatic artery, portal vein and hepatic vein image segmentation method and system. The method comprises the following steps: acquiring multi-phase medical image data of a liver region; performing region identification on the image data, and extracting hepatic duct, hepatic artery, portal vein and hepatic vein regions; executing structure tracking on the hepatic duct area to obtain a hepatic duct positioning result; carrying out improved contrast extraction on the hepatic artery region to obtain hepatic artery positioning data; performing directional segmentation analysis on the portal vein region to obtain a portal vein positioning result; performing branch angle extraction on the hepatic vein region in combination with the portal vein direction to obtain hepatic vein positioning data; taking the hepatic artery as a reference structure, performing elastic registration on each blood vessel structure, and generating registration data under a unified coordinate; and completing three-dimensional visualization based on a registration result. According to the method, multi-stage image joint segmentation and registration are realized, and the method has the technical advantage of high structural recognition integrity.

An intra-vessel transcatheter filter device (1) designed to capture and remove emboli, thus preventing distal embolization, comprising: • a tubular filter (2) comprising a flexible porous material and defined by a distal element and a proximal element, namely a main body (3) and a funnel (4); i. said main body (3) having a length adapted to extend within a suitable vessel zone; said main body (3) comprising: a) a distal end (5) that is adapted to be radially coupled with said zone and hermetically sealed to it when the device is in an active configuration, said distal end (5) being provided of selectively actionable closure means so that said distal end is designed to be open when the device is in an active configuration and closed before the device retraction, b) a proximal end (6); ii. said funnel (4) forming an extension of said main body (3), with the funnel base located at said proximal end (6). • a support structure assembly (8) comprising: i. a supporting catheter (11) extending within said main body (3), ii. one radially expandable distal structure (9) fixed to said distal end (5), iii. one radially expandable proximal structure (10) positioned in correspondence of said proximal end (6), said distal structure (9) and said proximal structure (10) being fixed at least in an end to said supporting catheter (11).

A system leverages a multimodal model to predict peripheral arterial disease (PAD) risk. The system provides a dynamic questionnaire leveraging a language model to generate questions in response to user input. From the dynamic questionnaire, the system identifies user-specific risk factor(s) for PAD. The system also receives sensor data recorded by health sensor(s) including biometric signals of the user. The system applies a sensor classification model to the sensor data to output clinical data associated with a health state of the user. The system applies a multimodal PAD risk prediction model to the identified user-specific risk factors and the clinical data to output a PAD risk prediction indicating whether the user is at risk for PAD. Based on the outputs, the system generates and transmits one or more personalized recommendations for the user for treating or mitigating PAD risk and / or control instructions for controlling operation of the health sensor(s) and / or the medical device(s).

The invention discloses an intelligent pressure regulation and control method and system for artery compression, and the method comprises the steps: collecting the arterial blood pressure waveform and vascular elasticity parameters of a puncture part of a patient in real time, and the multi-dimensional pressure data of a pressure sensor; constructing an initial pressure parameter set containing a pressure distribution gradient and a vascular response coefficient through a dynamic feature extraction algorithm; carrying out collaborative analysis on the initial pressure parameter set and blood flow characteristic parameters obtained through blood flow monitoring, and generating a regulation and control matrix containing an optimal compression force range and a time decay function; performing multi-target optimization processing on the regulation and control matrix through a parallel optimization algorithm to generate a real-time pressure control instruction set; based on the deviation value of the real-time pressure execution data fed back by the user interface and the blood flow monitoring data, a grading alarm mechanism is triggered, and a compression strategy is automatically corrected. By utilizing the embodiment of the invention, accurate regulation and control of the artery compression process can be realized, and the hemostatic effect is optimized and the medical quality is improved on the premise of ensuring the safety of a patient.

The invention relates to lauroyl cilostazol as well as a preparation method and application thereof. Wherein the lauroyl cilostazol is sterile, and preferably, the lauroyl cilostazol is a crystal. The invention further provides application of the lauroyl cilostazol in preparing medicines for treating cerebral infarction, cerebrovascular diseases, atherosclerosis, diabetic complications, peripheral vascular diseases, Reynolds diseases, intermittent claudication, ischemic heart diseases and acute coronary syndromes. The lauroyl cilostazol has the remarkable long-acting characteristic.

Medical systems, devices, and methods for determining whether a blood vessel is a vein or an artery. The system includes an optical fiber configured for insertion into a blood vessel coupled with a console having a light source, an optical receiver, processors, and logic stored in memory. The optical fiber includes sensors disposed along its length configured to determine a state or condition of the optical fiber. The state or condition can include a strain, movement, pressure, and / or temperature. The logic is configured to analyze reflected signals from the sensors to determine whether the optical fiber is inserted within an artery or within a vein. The logic may also determine a red-blue shift of a projected light to determine a blood flow direction with respect to the optical fiber.

The invention provides a peripheral artery disease patient rehabilitation management system based on a whole process, and relates to the technical field of peripheral artery disease patient rehabilitation management. The system comprises a patient screening and risk grading module, a rehabilitation evaluation module, an exercise prescription generation and dynamic adjustment module, an intelligent propaganda and education content pushing module and a quality control closed-loop management module. PAD patients are accurately screened through a medical data interface and an NLP technology, and the risk levels of the patients are dynamically evaluated in combination with an intelligent risk grading system; generating a personalized exercise prescription according to the evaluation report, complication and biological monitoring data, and guaranteeing the exercise safety through a dynamic threshold model and collaborative early warning; dynamic matching and timeliness pushing of propaganda and education contents are realized by using an improved KL divergence algorithm; and full-process quality closed-loop management is realized through the quality control closed-loop management module. The precision and safety of rehabilitation management of the PAD patient can be improved, medical resource configuration is optimized, and rehabilitation practice driven by full-process data is assisted.

The invention discloses a method for noninvasive diagnosis of pulmonary arterial hypertension and a related device, and relates to the technical field of artery detection.The method comprises the steps that an echocardiogram result and right heart catheter pulmonary artery pressure data of a suspected pulmonary artery patient are obtained; the echocardiogram result is a tricuspid regurgitation spectrum; grading the quality of the tricuspid regurgitation spectrum based on a TR spectrum quality grading standard according to the regurgitation spectrum missing degree of the tricuspid regurgitation spectrum; according to the echocardiogram result and the right heart duct pulmonary artery pressure data, on the basis of the quality grading result of the tricuspid regurgitation spectrum, a personalized pulmonary artery hypertension diagnosis model suitable for different patients is constructed; according to the pulmonary arterial hypertension diagnosis model, on the basis of the echocardiogram result of the target pulmonary arterial patient, a pulmonary arterial hypertension diagnosis result of the target pulmonary arterial patient is obtained, and personalized accurate diagnosis can be carried out on different pulmonary arterial hypertension patients under the noninvasive condition.

The present invention provides a system and method for treating tight, hard-to-cross calcified lesions in which an angioplasty balloon is used to dilate the lesions and provide shock waves to restore normal blood flow in a patient's artery. An exemplary device includes an elongated tube and a balloon wrapped circumferentially around the tube and sealed to a distal end of the tube. During treatment, the device is advanced into a patient's vasculature and the balloon is inflated with conductive fluid such that the balloon is fixed to walls of the vasculature proximal to the calcified lesion. The balloon includes at least one low-profile emitter positioned near the distal end of the balloon, which may be activated to generate shock waves to break loose calcifications in the lesion. After calcium in the tight lesion has been modified, the balloon can be deflated and advanced further into the lesion to continue treatment.

The invention discloses an anesthesia strategy generation system fusing time sequence data and a knowledge graph, and relates to the technical field of medical information processing. The method specifically comprises the steps that five types of vital sign data including arterial blood pressure, electrocardio and electroencephalogram are collected, correction is conducted in combination with traction marks and electrotome interference characteristics, and an analysis result is output; the inference analysis module executes double-track processing based on the analysis value, one track evaluates cortical suppression, shock and ventilation risks and generates a risk report, and the other track performs reverse arbitration when the blood oxygen data is abnormal; constructing a knowledge graph fusing the efficacy nonlinear cooperation equation, the age sensitive parameters and the drug administration sequence influence; and the strategy generation module integrates the multi-source data to generate a drug execution track, and executes fast and slow closed-loop regulation and control based on a risk report and an arbitration result. According to the invention, the adaptation capability of the system to individual differences, the abnormal signal identification and processing capability and the intelligent response level of the anesthesia strategy are improved, and the accuracy and safety of clinical anesthesia are significantly enhanced.

An embodiment includes a system comprising: an artery, a vein, and a nerve; a first length of tubing adjacent at least one of the vein, artery, and nerve; a second length of tubing to couple to the first length of tubing; and a pump comprising a number of actuators; wherein when the system when operating is configured such that (b)(i) the second length of tubing couples to at least one of the number of actuators, (b)(ii) ends of the first and second lengths of tubing are closed, (b)(iii) a second end of the first length of tubing is operatively coupled to a second end of the second length of tubing, (b)(v) the pump pulsates fluid within the first length of tubing in response to the number of actuators intermittently contacting the second length of tubing.

The invention discloses an artificial heart valve near-physiological pulsation fluid external evaluation device and method, and relates to the technical field of heart valve testing.The artificial heart valve near-physiological pulsation fluid external evaluation device comprises a supporting frame, a driving unit, a tested valve installation unit and an artery and peripheral loop unit, the driving unit provides power for liquid flowing, and the tested valve installation unit is used for fixing an artificial heart valve; and a liquid volume assembly and a resistance assembly of the artery and peripheral loop unit can simulate the compliance and resistance of aorta blood vessels and peripheral artery blood vessels, so that the pressure waveform simulation of the systemic circulation loop is more accurate. On the basis of the air cavity, the elastic corrugated pipes with different frequency responses are arranged, the compliance and rebound resilience of the aorta are simulated, a device for rapidly replacing the tested valve is designed, and the mechanical property of the simulated human body aorta is adjusted by adjusting the parameters such as the output frequency and the vibration amplitude of the driving unit; real pressure and flow waveforms under different physiological / pathological conditions are simulated, and a more accurate and convenient detection environment is realized.

A method of extracting a thrombus from a thrombus site in a cerebral artery of a patient by advancing a first catheter into an internal carotid artery of the patient; advancing a funnel catheter within the first catheter; moving the funnel catheter and the first catheter with respect to each other to place the funnel outside of the first catheter; expanding the funnel into contact with an inner wall of the internal carotid artery at or proximal to a distal end of a carotid siphon, thereby reducing blood flow past the funnel; advancing a clot-mobilizer distally through the first catheter toward the thrombus and beyond the carotid siphon; engaging thrombus material from the thrombus with the clot-mobilizer; moving the clot-mobilizer and thrombus material proximally at least partially into the funnel; applying suction to aspirate thrombus material; and moving the funnel, the clot-mobilizer and the thrombus material proximally within the vasculature.

An ultrasound-imaging system includes an ultrasound probe coupled with a console. Operations of the system can include detecting one or more blood vessels within the ultrasound image and identifying each blood vessel as a vein, an artery or other anatomic element using doppler ultrasound functionality of the ultrasound probe. Operations can also include determining a confidence for the blood vessel identification and defining a window for doppler ultrasound operation. Operations can further include assessing a blood flow rate within blood vessels, and superimposing notifications atop the ultrasound image pertaining to the identity of the blood vessel including a confidence for the identity.

The invention provides a device for achieving brachial artery compression hemostasis, and relates to the technical field of medical instruments.The device for achieving brachial artery compression hemostasis comprises a wearing assembly suitable for being bound to the upper arm of the human body and achieving device wearing; the pressure applying unit array assembly is arranged on the wearing assembly and is used for carrying out compression operation on a puncture point area on the upper arm of the human body; the distributed pressure sensing assembly is arranged on the wearing assembly, located on the outer side of the pressure applying unit array assembly and used for sensing contact pressure information of the pressure applying unit array assembly and the puncture point area; and the controller is used for regulating and controlling the compression operation based on the dynamic pressure distribution represented by the contact pressure information so as to maintain effective compression on the puncture point. According to the technical scheme, compression failure caused by slight change of the posture of the upper limbs of the patient can be effectively reduced.

The embodiment of the invention provides a continuous blood oxygen monitoring system in extracorporeal circulation and a control method thereof. The continuous blood oxygen monitoring system comprises a vein sensor, an artery sensor, a blood flow sensor, an oxygen sensor, a carbon dioxide sensor, a controller and a display, the vein sensor monitors the vein blood oxygen saturation degree; the artery sensor monitors arterial oxygen saturation and hematocrit; the blood flow sensor monitors the blood flow of the artery pipeline; the oxygen sensor monitors the oxygen concentration of the oxygenator; the carbon dioxide sensor monitors the carbon dioxide concentration of the oxygenator; the display provides an interaction control, responds to a trigger operation acting on the interaction control, sends an interaction instruction to the controller, and updates information displayed in an interaction interface according to the control of the controller; the controller receives the interaction instruction and executes processing corresponding to the interaction instruction; the processing includes controlling display information of the display; the display information comprises information corresponding to the monitoring parameters. The scheme ensures the safety and effectiveness of the treatment process.

The invention discloses a method and system for sensing health based on a fingertip wearable spectrum sensor and a computer program product, and the method comprises the steps: controlling a spectrum chip to collect characteristic spectrum data corresponding to an artery blood vessel projection region of a user according to a received index monitoring instruction; the characteristic spectrum data is obtained based on emission and reception of one or more light from ultraviolet light to near-infrared light; receiving the characteristic spectrum data sent by the spectrum chip, and calculating a calibration spectrum value based on the characteristic spectrum data; and the calibration spectrum value is sent to the intelligent terminal, so that the intelligent terminal calculates the physiological health index, analyzes and processes the physiological health index, and pushes a personalized adjustment scheme. The fingertip wearing type spectrum sensing glove is convenient to wear, rich characteristic spectrum data can be collected according to user requirements, the intelligent terminal can quickly and accurately calculate various physiological health indexes, the intelligent terminal is not limited to traditional heart rate and blood oxygen monitoring, and the intelligent terminal can further analyze and process the physiological health indexes.

The invention relates to the technical field of medical instruments, and discloses an adjustable femoral artery automatic pressurizing device which comprises a main shell, a position adjusting assembly is mounted at the top of the main shell, a moving shell is slidably connected to the middle of the main shell, a connecting column is fixedly connected to the bottom of the moving shell, an air bag is arranged at the bottom of the connecting column, and an air outlet is formed in the middle of the air bag. A compression head is fixedly connected to the bottom of the air bag, an angle adjusting and positioning assembly is installed on the side face of the main shell, a bandage rod is arranged on the side face of the angle adjusting and positioning assembly, a composite sensing module is installed in the middle of the compression head, and an air pipe is arranged in the movable shell. One end of the air pipe penetrates through the connecting column and is fixedly connected to the air hole of the air bag. By sensing physiological signals formed by blood flow and hematoma in real time, self-adaptive closed-loop adjustment of compression pressure is realized, so that hemostasis accuracy, individualized level and safety of the automatic femoral artery pressurizing device are improved.

The invention provides a non-invasive blood pressure estimation method, device and equipment, a storage medium and a product, and belongs to the technical field of biomedicine, and the method comprises the steps that an ECG signal and an ICG signal are preprocessed; generating physiological feature indexes, wherein the physiological feature indexes comprise conventional indexes and special indexes; determining an incidence relation between the conventional index and the basic peripheral vascular resistance parameter as well as the basic artery compliance parameter; inputting the conventional indexes into a pre-trained machine learning model, and outputting basic peripheral vascular resistance prediction parameters and basic artery compliance prediction parameters; performing dynamic correction according to the special indexes, and generating a target peripheral vascular resistance parameter and a target artery compliance parameter; and calculating and generating a blood pressure estimation result. According to the non-invasive blood pressure estimation method, device and equipment, the storage medium and the product, the accuracy, dynamic nature and stability of non-invasive blood pressure estimation can be improved.

The present invention provides a carotid artery pressurized hemostasis device for head and neck surgery, which belongs to the field of medical device technology. The device includes an adjustment mechanism, an arc-shaped rail is fixedly installed on the top of the adjustment mechanism, and a hemostasis device is movably installed on the inner side of the arc-shaped rail; the hemostasis device includes an arc-shaped block and a mounting hole. The hemostasis device of the present invention has significant advantages. During use, medical staff can conveniently adjust the angle and position of the hemostasis device according to the patient's wound condition. By rotating the second handle, the screw rod drives the slide, so that the hemostasis mechanism moves down smoothly to contact the wound. When pressure is applied, the buffer spring plays a role, effectively avoiding excessive pressure on the patient's neck, ensuring safe and comfortable operation. At the same time, the bottom plate moves up to squeeze the elastic water bag, and the water flows into the elastic hemostasis bag. As the slide moves further down, the elastic hemostasis bag expands and cooperates with the hemostasis plate, greatly improving the efficiency and accuracy of hemostasis, and providing strong protection for the treatment of patients.

The invention discloses an electronic sphygmomanometer with an atrial fibrillation detection function, an atrial fibrillation detection method and device and electronic equipment, and belongs to the technical field of medical instruments. The electronic sphygmomanometer comprises a cuff, a processor, a detection result output component, a pressure signal detection component and a piezoelectric signal detection component, the pressure signal detection component and the piezoelectric signal detection component are respectively used for collecting a pressure signal in the cuff in a pressure release stage in the current blood pressure measurement process and a Korotkoff sound signal generated by brachial artery pulsation; the processor is used for analyzing and processing the pressure signal and the Korotkoff sound signal, acquiring the signal time position and the amplitude of the Korotkoff sound signal, acquiring a pulse interval sequence of the current blood pressure measurement based on the signal time position, and acquiring an atrial fibrillation state classification result corresponding to the current blood pressure measurement based on the pulse interval sequence and the amplitude; and the detection result output component is used for outputting an atrial fibrillation state classification result. The electronic sphygmomanometer can accurately detect whether atrial fibrillation occurs or not.

The invention discloses a non-contact ECG signal monitoring method based on a millimeter wave radar, belongs to the field of ECG signal monitoring, realizes high-precision electrocardiogram reconstruction by simultaneously sensing chest vibration caused by heartbeat and carotid artery pulsation from the neck and fusing spatial-temporal characteristics, and solves the problems that a traditional scheme depends on electrodes and an existing radar technology cannot recover complete ECG. According to the method, non-contact ECG signal monitoring is carried out in a daily scene, and good privacy and comfort are achieved.

A sheath delivery system comprises an access device for insertion of one or more wires to extend in first and second directions within a blood vessel. The access device can include an elongated member with a lumen between a distal tip and proximal end, the lumen oriented to exit a patient, a footplate having a bore extending therethrough the footplate and configured to translate within the lumen between an initial state along the lumen and a rotated state anchoring the access device within a blood vessel, a first wire port through which a first wire enters and advances past the footplate into the blood vessel in a first direction, and a second wire port configured to guide a second wire into the lumen so that the second wire passes through the lumen and through the hollow bore of the footplate such that the second wire advances in the second direction.

The invention is applicable to the technical field of medical instruments, and provides a subskull epidural micro-invasive flexible brain-computer interface electrode, which comprises a plurality of electrode branches, each electrode branch comprises a linear flexible main body, and the flexible main body comprises a micro power supply circuit and a signal circuit which are solidified. A plurality of electrode units are arranged on the micro power supply circuit and the signal circuit at intervals, and the electrode units are electrically connected with the micro power supply circuit and the signal circuit. The brain-computer interface electrode is in a flexible line type, can be implanted into the middle artery of the meninx, does not need craniotomy, is a micro-invasive brain-computer interface, has data monitoring accuracy close to that of an invasive brain-computer interface, does not need to worry about inflammatory response, immunostimulation, biocompatibility, brain tissue damage and other adverse factors after long-term implantation, and is suitable for popularization and application. And the thrombogenic risk of a vein stent brain-computer interface does not exist.