Catheter Movement Research Articles

Comparison of Classical, Neural Network and Hybrid Models for Hysteretic Single-tendon Catheter Kinematics.

While robotic control of catheter motion can improve tip positioning accuracy, hysteresis arising from tendon friction and flexural deformation degrades kinematic modeling accuracy. In this paper, we compare the capabilities of three types of models for representing the forward and inverse kinematic maps of a clinical single-tendon cardiac catheter. Classical hysteresis models, neural networks and hybrid combinations of the two are included. Our results show that modeling accuracy is best when models are trained using motions corresponding to the anticipated clinical motions. For sinusoidal motions, recurrent neural network models provide the best performance. For point-to-point motions, however, a simple backlash model can provide comparable performance to a recurrent neural network.

Machine-Learning-Based Multi-Modal Force Estimation for Steerable Ablation Catheters.

Catheter-based cardiac ablation is a minimally invasive procedure for treating atrial fibrillation (AF). Electrophysiologists perform the procedure under image guidance during which the contact force between the heart tissue and the catheter tip determines the quality of lesions created. This paper describes a novel multi-modal contact force estimator based on Convolutional Neural Networks (CNNs) and Recurrent Neural Networks (RNNs). The estimator takes the shape and optical flow of the deflectable distal section as two modalities since frames and motion between frames complement each other to capture the long context in the video frames of the catheter. The angle between the tissue and the catheter tip is considered a complement of the extracted shape. The data acquisition platform measures the two-degrees-of-freedom contact force and video data as the catheter motion is constrained in the imaging plane. The images are captured via a camera that simulates single-view fluoroscopy for experimental purposes. In this sensor-free procedure, the features of the images and optical flow modalities are extracted through transfer learning. Long Short-Term Memory Networks (LSTMs) with a memory fusion network (MFN) are implemented to consider time dependency and hysteresis due to friction. The architecture integrates spatial and temporal networks. Late fusion with the concatenation of LSTMs, transformer decoders, and Gated Recurrent Units (GRUs) are implemented to verify the feasibility of the proposed network-based approach and its superiority over single-modality networks. The resulting mean absolute error, which accounted for only 2.84% of the total magnitude, was obtained by collecting data under more realistic circumstances in contrast to previous research studies. The decrease in error is considerably better than that achieved by individual modalities and late fusion with concatenation. These results emphasize the practicality and relevance of utilizing a multimodal network in real-world scenarios.

Cardio-respiratory motion compensation for coronary roadmapping in fluoroscopic imaging.

Inferring the shape and position of coronary artery poses challenges when using fluoroscopic image guidance during percutaneous coronary intervention (PCI) procedure. Although angiography enables coronary artery visualization, the use of injected contrast agent raises concerns about radiation exposure and the risk of contrast-induced nephropathy. To address these issues, dynamic coronary roadmapping overlaid on fluoroscopic images can provide coronary visual feedback without contrast injection. This paper proposes a novel cardio-respiratory motion compensation method that utilizes cardiac state synchronization and catheter motion estimation to achieve coronary roadmapping in fluoroscopic images. For more accurate cardiac state synchronization, video frame interpolation is applied to increase the frame rate of the original limited angiographic images, resulting in higher framerate and more adequate roadmaps. The proposed method also incorporates a multi-length cross-correlation based adaptive electrocardiogram (ECG)matching to address irregular cardiac motion situation. Furthermore, a shape-constrained path searching method is proposed to extract catheter structure from both fluoroscopic and angiographic image. Then catheter motion is estimated using a cascaded matching approach with an outlier removal strategy, leading to a final corrected roadmap. Evaluation of the proposed method on clinical x-ray images demonstrates its effectiveness, achieving a 92.8% F1 score for catheter extraction on 589 fluoroscopic and angiographic images. Additionally, the method achieves a 5.6-pixel distance error of the coronary roadmap on 164 intraoperative fluoroscopic images. Overall, the proposed method achieves accurate coronary roadmapping in fluoroscopic images and shows potential to overlay accurate coronary roadmap on fluoroscopic image in assisting PCI.

Omnipolar conduction velocity mapping for ventricular substrate characterization: Impact of CV estimation method and EGM type on in vivo conduction velocity measurements

BackgroundAreas of abnormal or heterogeneous conduction velocity (CV) are important ablation targets for ventricular tachycardias, yet precise assessment of CV in clinical contact mapping remains challenging. Numerous different CV estimation methods have been proposed. ObjectiveThis study aimed to compare the automated local activation time (LAT)–independent omnipolar-based CV estimation method termed wave speed (WS) with 4 established LAT-based methods to formally establish the quantitative differences between them. MethodsHigh-density contact maps in patients with structurally normal hearts during sinus rhythm (SR) and ventricular ectopy (VE) were retrospectively analyzed. CV was assessed and compared by 5 methods: omnipolar WS, gradient method, planar wavefront fitting, circular wavefront fitting, and radial basis function. CV variations based on electrogram (EGM) type (unipolar, bipolar, and omnipolar), catheter movement, and surrogate markers for catheter contact were analyzed. ResultsThe study included 23 patients (47.8% male; 45.7 ± 17.3 years) with 22 SR maps (11 left ventricle, 11 right ventricle) and 16 VE maps (9 left ventricle, 7 right ventricle). The WS algorithm yielded statistically significant higher CV estimates in SR (mean, 1.41 ± 0.18 m/s) and VE (mean, 1.23 ± 0.18 m/s) maps compared with all LAT-based estimation methods, with absolute differences ranging from 0.1 m/s to 0.81 m/s. Median pointwise differences in SR and VE between WS and LAT-based methods were high, ranging from 0.55 ± 0.15 m/s (WS vs planar wavefront fitting) to 0.67 ± 0.16 m/s (WS vs radial basis function). For LAT-based methods, use of unipolar EGMs yielded significantly higher CV estimates than bipolar or omnipolar EGMs in SR. ConclusionThe CV estimation method has an important, statistically significant impact on ventricular CV measurements. Future work will focus on how these differences affect identification of pathologic conduction slowing in scar-related substrate.

Assessment of pericardial adhesions by means of the EpiCO2 technique: Brighton Adhesion Classification

BackgroundEpicardial ablation complications are more frequent in patients with preexisting pericardial adhesions. As opposed to the dry puncture technique, the coronary vein exit and carbon dioxide (CO2) insufflation (EpiCO2) technique allows diagnosing pericardial adhesions before subxiphoid puncture. ObjectiveThis study aimed to evaluate the efficacy of the EpiCO2 technique in diagnosing pericardial adhesions prior to subxiphoid puncture. MethodsFollowing coronary vein exit, contrast was injected in the pericardial space, and adhesions classified using our novel Brighton Adhesion Classification (BAC) into BAC-0 (no adhesions), BAC-1 (dispersed adhesions), and BAC-2 (dense adhesions extending to the entire assessed area). CO2 insufflation allowed subclassification of BAC-1 adhesions into BAC-1a (not preventing epicardial access or restricting catheter movement) and BAC-1b (either preventing epicardial access or significantly limiting catheter movement). ResultsIntentional coronary vein exit (right atrial appendage exit in 1 case) was achieved in all 235 consecutive epicardial ablation procedures undertaken at our center. A diagnosis of BAC-0 was made in 219 cases (93.2%), BAC-1a in 9 cases (3.8%), BAC-1b in 2 cases (0.9%), and BAC-2 in 5 cases (2.1%). This led to not attempting subxiphoid puncture in 6 cases (2.6%) and abandoning epicardial mapping because of limited catheter movement in 1 case (0.4%). Access-related complications occurred in 7 cases (3%) only in the BAC-0 group. ConclusionThe EpiCO2 technique allows assessment of the presence of pericardial adhesions prior to attempting subxiphoid puncture for epicardial access, which may lead to a reduction in the procedural complications within this subset of patients.

Risk factors and prediction model construction for peripherally inserted central catheter-related infections

ObjectiveTo establish a predictive modeling for the risk of bloodstream infection associated with peripherally inserted central catheter (PICC). MethodsPatients receiving PICC treatment in Shenzhen People's Hospital from June 2020 to December 2020 were retrospectively enrolled and divided into the infection group and the non-infection group according to the presence and absence of PICC-related infections. Then, relevant clinical information of patients was collected and the predictors of PICC-related infection were screened by the least absolute shrinkage and selection operator regression (LASSO) model. Besides, multivariate logistic regression was used to analyze the influencing factors of PICC-related infection, A nomogram was constructed based on the results of the multivariate analysis. Ultimately, a receiver operating characteristic (ROC) curve was plotted to analyze the application value of influencing factors to predict PICC-related infections. ResultsA total of 505 patients were included, including 75 patients with PICC-related infections (14.85%). The main pathogen was gram-positive cocci. The predictors screened by LASSO included age >60 years, catheter movement, catheter maintenance cycle, insertion technique, immune function, complications, and body temperature ≥37.2 °C before PICC placement. Multivariate logistic regression analysis showed that independent risk factors of infections related to PICC included age >60 years [odds ratio (OR) = 1.722; 95% confidence interval (CI) = 1.312–3.579; P = 0.006], catheter movement (OR = 1.313; 95% CI = 1.119–3.240; P = 0.014), catheter maintenance cycle >7 days (OR = 2.199; 95% CI = 1.677–4.653; P = 0.000), direct insertion (OR = 1.036; 95% CI = 1.019–2.743; P = 0.000), poor immune function (OR = 2.322; 95% CI = 2.012–4.579; P = 0.000), complications (OR = 1.611; 95% CI = 1.133–3.454; P = 0.019), and body temperature ≥37.2 °C before PICC placement (OR = 1.713; 95% CI = 1.172–3.654; P = 0.012). Besides, the area under the ROC curve was 0.889. ConclusionPICC-related infections are associated with factors such as age >60 years, catheter movement, catheter maintenance cycle, insertion technique, immune function, complications, and body temperature ≥37.2 °C before PICC placement. Additionally, the LASSO model is moderately predictive for predicting the occurrence of PICC-related infections.

Temperature fluctuations during embryo transfer can be mitigated by optimizing transfer protocol

Research QuestionWhat impact do variations in embryo transfer catheter loading and movement procedures have on temperature and pH fluctuations during embryo transfer? DesignMock embryo transfers were conducted to test the impact of airflow/movement, use of catheter coverings and the type of workstation used for catheter loading on catheter temperature. A thermocouple probe inserted into the tip of the outer catheter or taped to the exterior of the inner catheter recorded temperature within the catheter every 5 sec from time of mock embryo loading (TL) up to 60 sec (TL +60s). Fluctuations in culture medium pH in embryo transfer dishes were monitored. ResultsCatheter temperature was lower at TL+15s (26.8 ±0.61°C) than TL (30.5 ±0.81°C, P <0.05). The rate of cooling during transit was slower when catheters were covered to reduce the cooling effect of air movement (P<0.05). Temperature was better maintained when catheters were loaded in a crib compared to a heated stage, until initiation of transit, when the rate of temperature decrease was similar. Culture medium pH increased faster when embryo transfer dishes remained on a heated stage during the procedure compared to within an open crib. ConclusionsTemperature loss during the ET procedure can be mitigated by reducing transit time and using catheter coverings. Use of a crib for catheter loading only improved temperature stability while the catheter remained in the crib, not during transit, and it reduced pH fluctuations during the procedure.

Evaluating the impact of external forces on peripheral intravenous catheter movement using ultrasound: A randomized pilot study.

A major contributor to peripheral intravenous catheter (PIVC) failure may be related to PIVC movement within the vein which is associated with vein wall damage. The magnitude of PIVC movement against the vein wall has not previously been quantified. This study aimed to examine PIVC movement within the vein when minor forces were applied to the PIVC. This was a prospective, pilot trial including healthy volunteers in an outpatient research laboratory. The primary objective was to examine the in movement (millimeters) of the PIVC using ultrasound with external pull forces (4, 5, and 6 lbs; 1.8, 2.3, and 2.7 kg, respectively) applied to the PIVC in random order. Participants (N = 11) were aged 40.36 ± 16.10 years with 54.55% being Male. Mean ± SD PIVC movement for 4, 5, and 6 lbs of force was 4.65 ± 1.88, 3.88 ± 2.28, and 5.25 ± 2.06 mm, respectively. There was substantial PIVC movement when a force was applied to the PIVC, but no statistically significant difference between 4, 5, and 6 lb forces (p > 0.05). When external pull forces were applied to the PIVC, substantial PIVC movement within the vein occurred in a healthy population. Strategies that reduce PIVC movement and/or remove or limit external pull forces from the PIVC are needed. Future studies on hospitalized patients are warranted to quantify vein wall injury and PIVC failure due to PIVC movement from various pull forces.

Impact of general anesthesia on ablation catheter stability during pulmonary vein isolation based on a novel measurement approach

Catheter ablation for atrial fibrillation (AF) during pulmonary vein isolation (PVI) is performed under general anesthesia (GA) or conscious sedation (CS). GA during PVI may improve treatment outcomes by improving catheter stability. However, the magnitude of GA-derived catheter stability compared with that of CS is unclear. We directly assessed catheter movement and determined the impact of GA compared with that of CS on ablation catheter stability during PVI. Patients who underwent initial ablation using the EnSite Precision™ mapping system were recruited and divided into two groups (GA and CS groups). The two groups were compared for ablation catheter stability during PVI based on the distance traveled by the catheter distal tip per second, clinical periprocedural characteristics, and periprocedural complications. Among 69 consecutively admitted patients, data of 30 patients (17 in the GA group and 13 in the CS group) and the distance traveled per second by the catheter on 148,976 points/patient were evaluated. The GA group had a significantly smaller catheter tip travel distance than the CS group (0.92 [0.82‒1.16] vs. 1.25 [1.14‒1.38], p = 0.01). Therefore, GA during PVI for AF provides greater catheter stability than CS and will contribute to more accessible and safer PVI procedures.

Gender differences in self-assessed performance and stress level during training of basic interventional radiology maneuvers

ObjectivesGender differences have been reported to influence medical training. We investigated gender differences encountered during training in interventional radiology maneuvers.MethodsCatheter handling was analyzed under standardized conditions in 64 participants naïve to endovascular procedures (26 women, 38 men). Objective (e.g., catheter pathway, catheter movements, required time) and subjective parameters (stress level) were recorded. The NASA-Task Load Index (NASA-TLX; 1–20 points) was used to assess participants’ stress levels and perceived workload.ResultsIn the easier tasks, no significant differences between male and female participants regarding catheter handling were observed. In the most complex task, female participants took themselves more time (688 ± 363 vs. 501 ± 230 s; p = 0.02), asked for help more frequently (n = 19 vs. n = 8) and earlier than men (203 ± 94 vs. 305 ± 142 s; p = 0.049), whereas men stood out by more agitated catheter handling (6.0 ± 1.8 vs. 4.8 ± 1.6 movements/s; p = 0.005). Overall, female participants perceived tasks to be more difficult (11.5 ± 4.2 vs. 9.6 ± 3.3; p = 0.016), perceived higher stress levels (8.9 ± 4.9 vs. 6.3 ± 4.4; p = 0.037), and rated their own performance lower (9.12 ± 3.3 vs. 11.3 ± 3.3; p = 0.009). However, female participants were able to correlate self-assessed with objective parameters correctly (r between −0.555 and −0.469; p = 0.004–0.018), whereas male participants failed to correctly rate their performance (p between 0.34 and 0.73). Stress levels correlated with objective parameters in males (r between 0.4 and 0.587; p < 0.005), but not in female participants.ConclusionPerceived stress levels, self-evaluation skills, and catheter handling differ greatly between untrained male and female participants trying to solve interventional radiological tasks. These gender-specific differences should be considered in interventional radiology training.Clinical relevance statementAs psychological aspects may influence individual working strategies gender-specific differences in self-perception while learning interventional radiology maneuvers could be essential regarding success in teaching and treatment outcomes.Key Points• After performing standardized training, 38 male and 26 female volunteers showed significant differences regarding objective and self-assessed performance, as well as in perceived workload while performing simulated endovascular catheter maneuvers.• After solving simulated endovascular radiological tasks, female participants were able to self-assess their objective performance much more accurately than male participants.• Women took more time to solve simulated endovascular tasks and asked earlier and more frequently for help than men.

Practical guidance to reduce radiation exposure in electrophysiology applying ultra low-dose protocols: a European Heart Rhythm Association review.

Interventional electrophysiology offers a great variety of treatment options to patients suffering from symptomatic cardiac arrhythmia. Catheter ablation of supraventricular and ventricular tachycardia has globally evolved a cornerstone in modern arrhythmia management. Complex interventional electrophysiological procedures engaging multiple ablation tools have been developed over the past decades. Fluoroscopy enabled interventional electrophysiologist throughout the years to gain profound knowledge on intracardiac anatomy and catheter movement inside the cardiac cavities and hence develop specific ablation approaches. However, the application of X-ray technologies imposes serious health risks to patients and operators. To reduce the use of fluoroscopy during interventional electrophysiological procedures to the possibly lowest degree and to establish an optimal protection of patients and operators in cases of fluoroscopy is the main goal of modern radiation management. The present manuscript gives an overview of possible strategies of fluoroscopy reduction and specific radiation protection strategies.

Novel automated “score mapping” of diaphragmatic compound motor action potential for the early detection of phrenic nerve injury during cryoablation

The proximity of phrenic nerve to right sided pulmonary veins (PV) make it susceptible to injury during cryoballoon ablation (CBA) for atrial fibrillation (AF). Monitoring of diaphragmatic compound motor action potentials (CMAP) obtained from lead aVF or modified surface ECG leads placed along the diaphragm have been used for early detection of phrenic nerve injury (PNI). 1 Schaerli N. Badertscher P. Spies F. et al. A Simplified Method to Detect Phrenic Nerve Injury During Cryoballoon Ablation of Atrial Fibrillation Using Lead aVF of the Surface ECG. Circ Arrhythm Electrophysiol. 2021 Aug; 14e009986https://doi.org/10.1161/CIRCEP.121.009986 Crossref Scopus (0) Google Scholar Thirty percent drop in CMAP amplitude has been shown in studies as the threshold for prevention of PNI. 2 Miyazaki S. Hachiya H. Taniguchi H. et al. Prospective Evaluation of Bilateral Diaphragmatic Electromyograms During Cryoballoon Ablation of Atrial Fibrillation. JCE. 2015; 26: 622-628 Google Scholar However, CMAP signals may be susceptible to respiratory variations, catheter movement, inadequate baseline amplitude making it difficult to monitor the change in CMAP. 3 Sharma P.S. Padala S.K. Thompson J.J. Gunda S. Koneru J.N. Ellenbogen K.A. Factors Influencing Diaphragmatic Compound Motor Action Potentials During Cryoballoon Ablation for Atrial Fibrillation. JCE. 2016; 7: 1384-1389 Google Scholar Score-map of the CMAP using template matching with 3D electroanatomic mapping system can be used to automate the monitoring of CMAP. The aims of this study were to assess the relationship of change in CMAP amplitude with change in score-map and then use the automated score-map prospectively for early detection of PNI during CBA.

Impact of System-F in Delivering Vascular Plugs for Aortic Side Branch Embolization During Endovascular Aneurysm Repair.

This study aimed to illustrate the utility of our original system to deliver vascular plugs into aortic side branches during endovascular aneurysm repair (EVAR). Our device, which we named "System-F," consists of a 14 Fr sheath, a 12 Fr long sheath with a side hole, a stiff guidewire as a shaft, and a parallelly-inserted delivery catheter navigated through the side hole into the aneurysm sac. Vertical motion and horizontal rotation of the side hole allow multidimensional movement of the delivery catheter within the aneurysm. This system was applied in 7 cases undergoing EVAR; 4 inferior mesenteric arteries and 14 lumbar arteries were embolized using vascular plugs. Type II endoleak (T2EL) was not observed in the follow-up survey of any case. Conclusion: The applicability of System-F for vascular plug placement in the side branches of abdominal aortic aneurysms has the potential to achieve high delivery capability and be widely applied for the prevention of T2EL. System-F has potential to change the strategies of pre-EVAR embolization.

Calibration of a three-state cell death model for cardiomyocytes and its application in radiofrequency ablation

Objective. Thermal cellular injury follows complex dynamics and subcellular processes can heal the inflicted damage if insufficient heat is administered during the procedure. This work aims to the identification of irreversible cardiac tissue damage for predicting the success of thermal treatments. Approach. Several approaches exist in the literature, but they are unable to capture the healing process and the variable energy absorption rate that several cells display. Moreover, none of the existing models is calibrated for cardiomyocytes. We consider a three-state cell death model capable of capturing the reversible damage of a cell, we modify it to include a variable energy absorption rate and we calibrate it for cardiac myocytes. Main results. We show how the thermal damage predicted by the model response is in accordance with available data in the literature on myocytes for different temperature distributions. When coupled with a computational model of radiofrequency catheter ablation, the model predicts lesions in agreement with experimental measurements. We also present additional experiments (repeated ablations and catheter movement) to further illustrate the potential of the model. Significance. We calibrated a three-state cell death model to provide physiological results for cardiac myocytes. The model can be coupled with ablation models and reliably predict lesion sizes comparable to experimental measurements. Such approach is robust for repeated ablations and dynamic catheter-cardiac wall interaction, and allows for tissue remodelling in the predicted damaged area, leading to more accurate in-silico predictions of ablation outcomes.

Extending bioelectric navigation for displacement and direction detection

PurposeBioelectric navigation is a navigation modality for minimally invasive endovascular procedures promising non-fluoroscopic navigation. However, the method offers only limited navigation accuracy between anatomical features and expects the tracked catheter to move only in one direction at all times. We propose to extend bioelectric navigation with additional sensing capabilities, allowing for the estimation of the distance traveled by the catheter, thereby improving accuracy between feature locations and allowing to track also under alternating forward- and backward motion.MethodsWe perform experiments in finite element method (FEM) simulations and in a 3D printed phantom. A solution for estimating the traveled distance using a stationary electrode is proposed, together with an approach on how to evaluate the signals obtained with this additional electrode. We investigate the effects of surrounding tissue conductance on this approach. Finally, the approach is refined in order to mitigate the effects of parallel conductance on the navigation accuracy.ResultsThe approach allows to estimate the catheter movement direction and the distance traveled. Simulations show absolute errors below 0.89 mm for non-conducting surrounding tissue, but errors up to 60.27 mm when the tissue is electrically conductive. This effect can be mitigated by a more sophisticated modeling (errors up to 33.96 mm). In experiments in a 3D printed phantom, the mean absolute error over 6 catheter paths is 6.3 mm, with standard deviations smaller than or equal to 1.1 mm.ConclusionsExtending the setup of bioelectric navigation with an additional stationary electrode allows to estimate the distance traveled by the catheter, as well as the movement direction. The effects of parallel conductive tissue could be partially mitigated in simulations, but further research is needed to investigate these effects in real biological tissue, and to bring the introduced errors down to a clinically acceptable level.

AB-453068-1 NOVEL ‘SCORE-MAPPING’ OF DIAPHRAGMATIC COMPOUND MOTOR ACTION POTENTIAL FOR EARLY DETECTION OF PHRENIC NERVE INJURY DURING CRYOABLATION

The proximity of the phrenic nerve to right-sided pulmonary veins makes it susceptible to injury during cryoballoon ablation (CBA) for atrial fibrillation (AF). Although there are no specific preprocedural predictors for phrenic nerve injury (PNI), monitoring of diaphragmatic compound motor action potentials (CMAP) has been used for the early detection of PNI. A 30% drop in CMAP amplitude has been shown in animal and clinical studies as the threshold for the prevention of PNI The aims of this study were to assess the relationship of change in CMAP amplitude with change in score map and then use the automated score map prospectively for early detection of PNI during CBA In the first half of the study, we paced the phrenic nerve at 10,8,6,4,2 milliamperes or till loss of capture in 20 pts. The relationship between the change in amplitude of CMAP with a corresponding change in the score map was studied by linear regression. 30% drop in CMAP amplitude was associated with a score map of 89%(R2 0.77). In the second half of the study, we used a score map threshold of 90% and studied 84 pts. Ablation was stopped if the score map of CMAP dipped below 90% consistently for >4 beats to take respiratory variation into account A total of 174 cryo applications were done for the right-sided veins in 84 pts. A consistent score-map >98% was obtained in all pts before the beginning of the CBA. Ablation had to be stopped in 13 pts due to a drop in the score map or CMAP amplitude or decreased diaphragm contraction. 5 pts had transient PNI. Change in score map was noticeable before change in CMAP amplitude or decrease in diaphragm contraction. In 8 pts drop in the score map was attributed to catheter movement which was noted by the change in catheter position on the 3D mapping system. Score-map of CMAP returned to >98% with catheter adjustment or within 5 minutes of ablation termination along with improvement of CMAP amplitude in all cases. No pts were noted to have persistent PNI at the end of the procedure Beat-to-beat changes in CMAP amplitude can be noted with respiratory variation or catheter movement making it difficult to monitor the change in amplitude. By using an automated score rather than continuously measuring CMAP amplitude, score mapping can make monitoring changes in CMAP amplitude easier. This descriptive study demonstrates that a 90 % score-map threshold correlates with a 30% drop in CMAP amplitude and can be safely and reliably used for the early detection of PNI

Sensing Technologies for Extravasation Detection: A Review.

Peripheral intravenous catheters are administered for various purposes, such as blood sampling or the infusion of contrast agents and drugs. Extravasation happens when the catheter is unintentionally directed outside of the vein due to movement of the intravascular catheter, enhanced vascular permeability, or occlusion of the upstream vein. In this article, extravasation and its mechanism are discussed. Subsequently, the sensorized devices (e.g., single sensor and multimodal detection) to identify the extravasation phenomena are highlighted. In this review article, we have shed light on both physiological and engineering points of view of extravasation and its detection approaches. This review provides an overview on the most recent and relevant technologies that can help in the early detection of extravasation.

Explicit dynamics simulation of the catheter movement during bronchoscopic sampling of pulmonary nodules

The paper presents an explicit dynamics approach for modelling the catheter movement inside the bronchial tree. A numerical model of the bronchial tree is considered, and a straight beam is used to simulate the catheter. The purpose is to test whether such approach can be used for modeling catheter insertion process as a means for studying tissue interaction tools and for preintervention planning. It is shown that by proper combination of the imposed initial and boundary conditions it is possible to considerably reduce the computational cost while obtaining realistic physical tissue-tool interaction.

Incidence of radiculopathy following lumboperitoneal shunt placement without fluoroscopy for normal pressure hydrocephalus.

Spinal catheter insertion in lumboperitoneal shunt (LPS) surgery for normal pressure hydrocephalus (NPH) can result in radiculopathy due to mechanical irritation of the nerve roots of the cauda equina. Here, we analyzed the position of LPS shunts placed without portable fluoroscopy in 72 patients, a subset of whom developed postoperative radiculopathy. We retrospectively analyzed how frequently 72 consecutive NPH patients experienced radiculopathy following LPS catheter placement performed without intraoperative fluoroscopy. The rate of incorrect catheter placement was 15.3% (11/72 cases). We observed that is, downward placement in 6.9% (5/72 cases), hyperflexion in 6.9% (5/72 cases), and subcutaneous migration in 1.4% (1/72 cases) patients. One patient with initial correct LPS placement developed radicular pain 5-day postoperatively attributed to 1-cm of catheter movement; they recovered simply by utilizing oral analgesics for 1-month duration. LPS insertion without fluoroscopic guidance resulted in a 15.3% risk of spinal catheter displacement. We suggest, therefore, that intraoperative imaging guidance be utilized for the placement of LPS in patients with NPH and/or for other pathology to avoid the 15.3% risk of postoperative radiculopathy.

Active Tracking-based cardiac triggering for MR-thermometry during radiofrequency ablation therapy in the left ventricle.

Cardiac MR thermometry shows promise for real-time guidance of radiofrequency ablation of cardiac arrhythmias. This technique uses ECG triggering, which can be unreliable in this situation. A prospective cardiac triggering method was developed for MR thermometry using the active tracking (AT) signal measured from catheter microcoils. In the proposed AT-based cardiac triggering (AT-trig) sequence, AT modules were repeatedly acquired to measure the catheter motion until a cardiac trigger was identified to start cardiac MR thermometry using single-shot echo-planar imaging. The AT signal was bandpass filtered to extract the motion induced by the beating heart, and cardiac triggers were defined as the extremum (peak or valley) of the filtered AT signal. AT-trig was evaluated in a beating heart phantom and in vivo in the left ventricle of a swine during temperature stability experiments (6 locations) and during one ablation. Stability was defined as the standard deviation over time. In the phantom, AT-trig enabled triggering of MR thermometry and resulted in higher temperature stability than an untriggered sequence. In all in vivo experiments, AT-trig intervals matched ECG-derived RR intervals. Mis-triggers were observed in 1/12 AT-trig stability experiments. Comparable stability of MR thermometry was achieved using peak AT-trig (1.0 ± 0.4°C), valley AT-trig (1.1 ± 0.5°C), and ECG triggering (0.9 ± 0.4°C). These experiments show that continuously acquired AT signal for prospective cardiac triggering is feasible. MR thermometry with AT-trig leads to comparable temperature stability as with conventional ECG triggering. AT-trig could serve as an alternative cardiac triggering strategy in situations where ECG triggering is not effective.