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OBJECTIVE Deep brain stimulation (DBS) of the centromedian thalamic nucleus has been reportedly used to treat severe Tourette syndrome, yielding promising outcomes. However, it remains unclear how DBS electrode position and stimulation parameters modulate the specific area and related networks. The authors aimed to evaluate the relationships between the anatomical location of stimulation fields and clinical responses, including therapeutic and side effects. METHODS The authors collected data from 8 patients with Tourette syndrome who were treated with DBS. The authors selected the active contact following threshold tests of acute side effects and gradually increased the stimulation intensity within the therapeutic window such that acute and chronic side effects could be avoided at each programming session. The patients were carefully interviewed, and stimulation-induced side effects were recorded. Clinical outcomes were evaluated using the Yale Global Tic Severity Scale, the Yale-Brown Obsessive-Compulsive Scale, and the Hamilton Depression Rating Scale. The DBS lead location was evaluated in the normalized brain space by using a 3D atlas. The volume of tissue activated was determined, and the associated normative connective analyses were performed to link the stimulation field with the therapeutic and side effects. RESULTS The mean follow-up period was 10.9 ± 3.9 months. All clinical scales showed significant improvement. Whereas the volume of tissue activated associated with therapeutic effects covers the centromedian and ventrolateral nuclei and showed an association with motor networks, those associated with paresthesia and dizziness were associated with stimulation of the ventralis caudalis and red nucleus, respectively. Depressed mood was associated with the spread of stimulation current to the mediodorsal nucleus and showed an association with limbic networks. CONCLUSIONS This study addresses the importance of accurate implantation of DBS electrodes for obtaining standardized clinical outcomes and suggests that meticulous programming with careful monitoring of clinical symptoms may improve outcomes.

OBJECTIVE Electrophysiologic mapping (EM) has been instrumental in advancing neuroscience and ensuring accurate lead placement for deep brain stimulation. However, EM is associated with increased operative time, expense, and potential risk. Intraoperative imaging to verify lead placement provides an opportunity to reassess the clinical role of EM. We investigated whether EM 1) provides new information that corrects suboptimal preoperative target selection by the physician or 2) simply corrects intraoperative stereotactic error, which can instead be quickly corrected with intraoperative imaging. METHODS Deep brain stimulation lead location errors were evaluated by measuring whether repositioning leads based on EM directed the final lead placement 1) away from or 2) toward the original target. We retrospectively identified 50 patients with 61 leads that required repositioning directed by EM. The stereotactic coordinates of each lead were determined with intraoperative computed tomography. RESULTS In 45 of 61 leads (74%), the electrophysiologically directed repositioning moved the lead toward the initial target. The mean radial errors between the preoperative plan and targeted contact coordinates before and after repositioning were 2.2 and 1.5 mm, respectively (P < 0.001). Microelectrode recording was more likely than test stimulation to direct leads toward the initial target (88% vs. 63%; P = 0.03). The nucleus targeted was associated with the likelihood of moving toward the initial target. CONCLUSIONS Electrophysiologic mapping corrected primarily for errors in lead placement rather than providing new information regarding errors in target selection. Thus, intraoperative imaging and improvements in stereotactic techniques may reduce or even eliminate dependence on EM.

Inadvertent malpositioning of a cardiac pacing lead into the left heart chambers is a rare complication of transvenous pacing. We report a patient with a history of a transient ischemic attack and chronic chest pain whose left atrial pacing lead location was revealed by transesophageal three-dimensional (3D) echocardiography during evaluation of an inter-atrial shunt.

BACKGROUND: There is considerable debate regarding the use of intraoperative microelectrode recording (MER) in deep brain stimulation (DBS). OBJECTIVE: To determine if the use of intraoperative MER impacts the final position of the lead implant in DBS of the subthalamic nucleus (STN) and globus pallidus (GPi) and to evaluate the incidence of complications. METHODS: The authors conducted a retrospective chart review of all patients who underwent STN and GPi DBS with MER, at the University of Texas Health Science Center in Houston from June 1, 2009 to October 1, 2013 to compare initial and final coordinates. Hemorrhagic and infectious complications were reviewed. RESULTS: A total of 90 lead implants on 46 patients implanted at the center during this time period were reviewed and included in the study. A statistically significant difference between the initial and final coordinates was observed in the superior-inferior direction with a mean difference of 0.40 mm inferiorly (±0.96 mm, P

Objective: During deep brain stimulation (DBS) surgery, microelectrode recording (MER) leads to target refinement from the initial plan in 30% to 47% of hemispheres; however, it is unclear whether the DBS lead ultimately resides within the MER-optimized target in relation to initial radiographic target coordinates in these hemispheres. This study aimed to determine the frequency of discordance between radiographic and neurophysiologic nucleus and whether target optimization with MER leads to a significant change in DBS lead location away from initial target. Methods: Consecutive cases of DBS surgery with MER using intraoperative computed tomography were included. Coordinates of initial anatomic target (AT), MER-optimized target (MER-O) and DBS lead were obtained. Hemispheres were categorized as “discordant” (D) if there was a suboptimal neurophysiologic signal despite accurate targeting of AT. Hemispheres where the first MER pass was satisfactory were deemed “concordant” (C). Coordinates and radial distances between 1) AT/MER-O; 2) MER-O/DBS; and 3) AT/DBS were calculated and compared. Results: Of the 273 hemispheres analyzed, 143 (52%) were D, and 130 (48%) were C. In C hemispheres, DBS lead placement error (mean ± standard error of the mean) was 0.88 ± 0.07 mm. In D hemispheres, MER resulted in significant migration of DBS lead (mean AT-DBS error 2.11 ± 0.07 mm), and this distance was significantly greater than the distance between MER-O and DBS (2.11 vs. 1.09 mm, P < 0.05). Directional assessment revealed that the DBS lead migrated in the intended direction as determined by MER-O in D hemispheres, except when the intended direction was anterolateral. Conclusions: Discordance between radiographic and neurophysiologic target was seen in 52% of hemispheres, and MER resulted in appropriate deviation of the DBS lead toward the appropriate target. The actual value of the deviation, when compared with DBS lead placement error in C hemispheres, was, on average, small.

Recent publications have reported the feasibility of atrioventricular node ablation (AVNA) and concomitant His-bundle pacing guided by an electroanatomic tridimensional mapping system (ETMS). We report the case of a 65-year-old female patient in which zero fluoroscopy left bundle branch pacing and AVNA were performed guided just by ETMS. Optimal device functioning, electrical parameters stability, and correct lead location were observed 24 h and 30 days after the procedure. In selected cases, in which ionizing radiation is not recommended, this technique may represent an alternative for performing both interventions in the same procedure. Objective Left bundle branch pacing is a physiological form of ventricular pacing achievable with zero fluoroscopy, being a feasible alternative technique when fluoroscopy is not recommended.

Background HB pacing is a promising approach to achieve physiological pacing, but its efficacy and long-term effects require further validation. In current study, we deemed to investigate the effect of the His bundle pacing (HBP) lead location on pacing parameters. Methods 2D echocardiography imaging was performed after successful implantation, according to which the patients were divided into groups A (whose His lead tips were at the atrial side) and B (whose His lead tips were at the ventricular side). The capture thresholds, sensing values, and H-V intervals between the two groups were compared. Results Thirteen patients were in group A and 16 patients were in group B. The average capture thresholds during, 1 month, and 1 year after operation were 1.20 ± 0.34, 0.69 ± 0.29, and 0.92 ± 0.80 V/0.5 ms for group A and 1.14 ± 0.43, 0.81 ± 0.39, and 0.98 ± 0.59 V/0.5 ms for group B, respectively. The difference between the two groups was not significant. The threshold values in both groups decreased significantly in 1 month and slightly increased in 1 year. The sensing values of group A were 1.87 ± 0.82, 1.95 ± 0.76, and 1.88 ± 0.75 mV, while those of group B were 4.53 ± 1.37, 4.69 ± 1.38, and 4.59 ± 1.42 mV. The difference among the three time points was not significant. However, the sensing values in group A were consistently significantly lower than those in group B. The HV interval in group A was significantly longer than that in group B. Conclusions The implantation site of HBP leads has a significant effect on sensing values for that His leads crossing the tricuspid annulus toward the ventricle are associated with higher sensing values, compared to a more proximal location. Meanwhile, lead location has no evident effect on capture thresholds that is improved significantly shortly after operation.

Subthalamic nucleus (STN) deep brain stimulation (DBS) is an established therapy for Parkinson’s disease motor symptoms. The ideal site for implantation within STN, however, remains controversial. While many argue that placement of a DBS lead within the sensorimotor territory of the STN yields better motor outcomes, others report similar effects with leads placed in the associative or motor territory of the STN, while still others assert that placing a DBS lead “anywhere within a 6-mm-diameter cylinder centered at the presumed middle of the STN (based on stereotactic atlas coordinates) produces similar clinical efficacy.” These discrepancies likely result from methodological differences including targeting preferences, imaging acquisition and the use of brain atlases that do not account for patient-specific anatomic variability. We present a first-in-kind within-patient demonstration of severe mood side effects and minimal motor improvement in a Parkinson’s disease patient following placement of a DBS lead in the limbic/associative territory of the STN who experienced marked improvement in motor benefit and resolution of mood side effects following repositioning the lead within the STN sensorimotor territory. 7 Tesla (7 T) magnetic resonance imaging (MRI) data were used to generate a patient-specific anatomical model of the STN with parcellation into distinct functional territories and computational modeling to assess the relative degree of activation of motor, associative and limbic territories.

International audience; Introduction: Causes of non-response to cardiac resynchronization therapy (CRT) include mechanical dyssynchrony, myocardial scar, and suboptimal left ventricular (LV) lead location. We aimed to assess the utility of Late Iodine Enhancement Computed Tomography (LIE-CT) with image subtraction in characterizing CRT non-response. Methods: CRT response was defined as a decrease in LV end-systolic volume > 15% at 6 months. LIE-CT was performed after 6 months, and analyzed global and segmental dyssynchrony, myocardial scar, coronary venous anatomy, and position of LV lead relative to scar and segment of latest mechanical contraction. Results: We evaluated 29 patients (age 71 ± 12 years; 72% men) including 18 (62%) responders. All metrics evaluating residual dyssynchrony such as wall motion index and wall thickness index were worse in non-responders. There was no difference in presence and extent of scar between responders and non-responders. However, in non-responders, the LV lead was more often over an akinetic/dyskinetic area (72% vs. 22%, p = .007), a fibrotic area (64% vs. 8%, p = .0007), an area with myocardial thickness < 6 mm (82% vs. 22%, p = .002), and less often concordant with the region of maximal wall thickness (9% vs. 72%, p = .001). Among the 11 non-responders, eight had at least another coronary venous branch visualized by CT, including three (27%) coursing over a potentially interesting myocardial area (free of scar, with normal wall motion, and with a myocardial thickness ≥6 mm). Conclusion: LIE-CT with image subtraction allows a comprehensive characterization of patients after CRT and may provide clues for management of non-responders.

We aimed to evaluate the electrical characteristics and pacing parameters at different locations of His-Purkinje system pacing. Patients who successfully underwent His-Purkinje system pacing with bradycardia indications from April 2018 to August 2019 were retrospectively analyzed according to the lead location confirmed by visualization of the tricuspid value annulus, postoperative echocardiography, and pacing electrocardiogram. The electrical characteristics and pacing parameters were compared among these patients. A total of 135 patients were retrospectively analyzed. Among them, 30 patients received atrial side HBP (aHBP group), 52 received ventricular side HBP (vHBP group), and 53 received left bundle branch pacing (LBBP group). The proportion of non-selective pacing was significantly lower in aHBP group (30.0%) than in vHBP (75.0%) and LBBP group (90.6%). LBBP had significantly shorter procedural and fluoroscopic duration than aHBP and vHBP. The capture threshold was significantly higher (1.07 ± 0.26 V/1.0 ms vs. 0.89 ± 0.22 V/1.0 ms vs. 0.77 ± 0.18 V/0.4 ms, P < 0.01, respectively), and the R-wave amplitude was significantly lower (3.71 ± 1.72 mV vs. 5.81 ± 2.37 mV vs. 10.27 ± 4.71 mV, P < 0.05 respectively) in aHBP group than those in the other two groups at implantation and during 3-month follow-up. No significant differences were observed in complications among groups during 3-month follow-up. VHBP and LBBP had better pacing performances than aHBP and might be more ideal pacing methods for bradycardia patients.

Background Lead-induced tricuspid regurgitation (TR) after cardiac implantable electronic device (CIED) implantation is not fully understood. This study aimed to reveal the features of lead-induced TR by 3-dimensional echocardiography (3DE) in patients with heart failure (HF) events after CIED implantation.Methods and Results:In 143 patients, 3DE assessments for the tricuspid valve (TV) and right ventricular morphologies were sequentially performed within 3 days after CIED implantations, during TR exacerbations, and at ≥6 months after TR exacerbations. TR exacerbations were observed in 29 patients (median 10 months after CIED implantation, range 1-28 months), 15 of whom had lead-induced TR. In the 29 patients, the tenting height of the TV, tricuspid annular (TA) height, and TA area at baseline were independent predictors for worsening TR. In patients with lead-induced TR, tenting height of the TV and TA area were identified as the risk factors. In addition, all patients with a lead positioned on a leaflet immediately after CIED implantations developed lead-induced TR. At follow up, TR exacerbation of lead-induced TR persisted with TA remodeling, but it was improved in the lead non-related-TR group. Conclusions TA remodeling at baseline and a lead location on a leaflet immediately after CIED implantation were associated with lead-induced TR in patients with HF events after CIED implantation. Persistent TA remodeling may make lead-induced TR refractory against HF treatments.

Cardiac arrhythmia is associated with high morbidity, and its underlying mechanisms are poorly understood. Computational modelling and simulation approaches have the potential to improve standard-of-care therapy for these disorders, offering deeper understanding of complex disease processes and sophisticated translational tools for planning clinical procedures. This review provides a clinician-friendly summary of recent advancements in computational cardiology. Organ-scale models automatically generated from clinical-grade imaging data are used to custom tailor our understanding of arrhythmia drivers, estimate future arrhythmogenic risk and personalise treatment plans. Recent mechanistic insights derived from atrial and ventricular arrhythmia simulations are highlighted, and the potential avenues to patient care (eg, by revealing new antiarrhythmic drug targets) are covered. Computational approaches geared towards improving outcomes in resynchronisation therapy have used simulations to elucidate optimal patient selection and lead location. Technology to personalise catheter ablation procedures are also covered, specifically preliminary outcomes form early-stage or pilot clinical studies. To conclude, future developments in computational cardiology are discussed, including improving the representation of patient-specific fibre orientations and fibrotic remodelling characterisation and how these might improve understanding of arrhythmia mechanisms and provide transformative tools for patient-specific therapy.

Background: In this study, we describe a technique of optimizing the accuracy of frameless deep brain stimulation (DBS) lead placement through the use of a cannula poised at the entry to predict the location of the fully inserted device. This allows real-time correction of error prior to violation of the deep gray matter. Methods: We prospectively gathered data on radial error during the operative placements of 40 leads in 28 patients using frameless fiducial-less DBS surgery. Once the Nexframe had been aligned to target, a cannula was inserted through the center channel of the BenGun until it traversed the pial surface and a low-dose O-arm spin was obtained. Using 2 points along the length of the imaged cannula, a trajectory line was projected to target depth. If lead location could be improved, the cannula was inserted through an alternate track in the BenGun down to target depth. After intraoperative microelectrode recording and clinical assessment, another O-arm spin was obtained to compare the location of the inserted lead with the location predicted by the poised cannula. Results: The poised cannula projection and the actual implant had a mean radial discrepancy of 0.75 ± 0.64 mm. The poised cannula projection identified potentially clinically significant errors (avg 2.07 ± 0.73 mm) in 33% of cases, which were reduced to a radial error of 1.33 ± 0.66 mm (p = 0.02) after correction using an alternative BenGun track. The final target to implant error for all 40 leads was 1.20 ± 0.52 mm with only 2.5% of errors being >2.5 mm. Conclusion: The poised cannula technique results in a reduction of large errors (>2.5 mm), resulting in a decline in these errors to 2.5% of implants as compared to 17% in our previous publication using the fiducial-less method and 4% using fiducial-based methods of DBS lead placement.

It is well recognized that a high burden of right ventricular pacing results in deleterious clinical outcomes over the long term. His bundle pacing can achieve optimal ventricular synchronization; however, relatively high pacing thresholds, low R-wave amplitudes, and the long-term performance have been concerns. Recently, left ventricular (LV) septal endocardium pacing (LVSP) has demonstrated improved acute haemodynamics. Another novel technique of intraseptal left bundle branch pacing (LBBP) via transvenous approach has been adopted rapidly and has demonstrated its feasibility and effectiveness. This article reviews the clinical application and differences between LVSP and LBBP. Compared with LVSP, LBBP has strict criteria for left conduction system capture and lead location. In addition to LV septal capture it also stimulates the proximal left bundle branch, resulting in rapid and physiological LV activation. With a uniformity and standardization of the implant procedure and definitions, it may be possible to achieve widespread application of this form of physiological pacing.

Objectives To characterize 3D electroanatomical mapping (EAM) of the His bundle (HB) region. Background Visualization of selective (S) and nonselective (NS) HB capture areas by EAM has not been described and may help guide HB pacing (HBP). Methods EAM was performed via NavX system in 17 patients (pts) undergoing HBP. HB cloud, S-HB, NS-HB, and right bundle (RB) capture areas were mapped. Results S-HBP areas were identified in 11, NS-HBP in 14, and RB in 11 pts. Two NS-HBP areas (upper and lower) either separated by S-HBP (8 pts) or almost contiguous (5 pts) were observed. S-HBP area measured: 1.1 ± 0.9 cm2 , NS upper: -1.2 ± 0.9 cm2 , NS lower: -1.2 ± 0.9 cm2 , RB: -1.7 ± 1.3 cm2 , total His cloud: -4.1 ± 2.7 cm2 . Electrocardiogram (ECG) pacemaps were different between upper and lower NS-HBP areas in 13/14 pts (p = .006). ECG differences between NS clouds were present in inferior leads in 9 pts (more negative QRS complex from lower NS area) and in precordial leads in 5 pts. There was no correlation between HBP lead location and capture threshold. R-wave amplitude was higher at more distal locations on HB cloud (p = .02). Conclusion (1) Pacemapping identifies distinct regions that may correspond to HB anatomy. (2) A linear S-HBP area is typically surrounded by two separate NS areas. (3) Pace-map ECGs from upper and lower NS-HBP areas have different morphologies. (4) These EAM features and pace-mapping may be helpful to the implanter.

Background An accurate and precise surgical procedure is crucial for patient safety and treatment efficacy of deep brain stimulation (DBS). Objectives To investigate the characteristics of intracranial lead bending phenomenon after DBS, and to suggest the methods to avoid bending-related complications. Methods A retrospective review of brain computed tomography scans after DBS was performed. Using 3-dimensional reconstruction, the maximal distance between the planned trajectory and actual lead location was measured. When the distance exceeded the lead body diameter, the lead was considered bent. The distance between the bending point and planned trajectory, and the relative direction between the bending point and lead securing site were analyzed. Changes over time in the range of lead bending and depth were analyzed when possible. Results A total of 190 implanted leads in 102 patients were analyzed; 104 leads (54.7%) were bent. The average deviation of bent leads was 2.3 mm (range, 1.3–7.1 mm). Thirty-five (18.4%) and seven leads (3.7%) had deviations exceeding twice and three times the lead body diameter, respectively. Angles between the deviation point and securing site at the skull ranged from 135–180° in 83 leads (53.2%), 45–135° in 58 (37.2%), and 0–45° in 15 (9.6%). Among 17 leads that were initially bent, 16 had less deviation compared to baseline. The lead depth increased in 35 (92.1%) of 38 leads by 1.2 mm (range, 0.1–4.7 mm). Conclusion The extent of lead bending should be considered during the planning and procedural phases of intracranial lead implantation for DBS.

The authors aimed to evaluate the association of left ventricular (LV) lead location and long-term outcomes in MADIT-CRT (Multicenter Automatic Defibrillator Implantation With Cardiac Resynchronization Therapy).There is limited data on the association of lead location with long-term clinical outcomes in patients with cardiac resynchronization therapy with defibrillator (CRT-D).The LV lead location was classified in 797 patients with CRT-D, in 569 patients with left bundle branch block (LBBB), in 228 patients with non-LBBB, and in 505 patients with an implantable cardioverter-defibrillator (ICD) only. Leads were classified into apical (n = 83) and non-apical (n = 486); with the non-apical LV leads further categorized into anterior (n = 99) and posterior/lateral (n = 387) within LBBB. All-cause mortality and heart failure (HF) events were assessed using Kaplan-Meier and Cox analyses.In CRT-D patients with LBBB and posterior/lateral LV lead location, there was an association with a significant reduction in long-term all-cause mortality (hazard ratio [HR]: 0.54, 95% confidence interval [CI]: 0.37 to 0.79; p = 0.001), and HF events (HR: 0.44, 95% CI: 0.33 to 0.60; p 0.001) compared to an ICD only, accompanied with better LV reverse remodeling. CRT-D patients with LBBB and an anterior LV lead location were shown to be associated with a significant reduction in HF events compared to an ICD only (anterior HR: 0.50, 95% CI: 0.30 to 0.82; p = 0.006); however, no association with mortality reduction was observed from CRT-D versus an ICD only. CRT-D was not associated with improved outcomes in non-LBBB patients, regardless of LV lead location.In mild HF patients with LBBB and an implanted CRT-D, lateral/posterior, and anterior LV lead locations are similarly associated with reduction in the risk of HF or death events compared to ICD alone. Mortality benefit derived from CRT-D is associated only with patients with lateral/posterior LV lead location. An apical LV lead location should be avoided due to the early risk of death whenever possible. (Multicenter Automatic Defibrillator Implantation With Cardiac Resynchronization Therapy [MADIT-CRT], NCT00180271; Multicenter Automatic Defibrillator Implantation Trial With Cardiac Resynchronization Therapy Post Approval Registry [MADIT-CRT-PAR], NCT01294449; and MADIT-CRT Long-Term International Follow-Up Registry - Europe, NCT02060110).

Background Cardiac Resynchronization Therapy (CRT) in dyssynchronous heart failure patients is ineffective in 20–30% of cases. Sub-optimal left ventricular (LV) pacing location can lead to non-response, thus there is interest in LV lead location optimization. Invasive acute haemodynamic response (AHR) measurements have been used to optimize the LV pacing location during CRT implantation. In this manuscript, we aim to predict the optimal lead location (AHR>10%) with non-invasive computed tomography (CT) based measures of cardiac anatomical and mechanical properties, and simulated electrical activation times. Methods Non-invasive measurements from CT images and ECG were acquired from 34 patients indicated for CRT upgrade. The LV lead was implanted and AHR was measured at different pacing sites. Computer models of the ventricles were used to simulate the electrical activation of the heart, track the mechanical motion throughout the cardiac cycle and measure the wall thickness of the LV on a patient specific basis. Results We tested the ability of electrical, mechanical and anatomical indices to predict the optimal LV location. Electrical (RV-LV delay) and mechanical (time to peak contraction) indices were correlated with an improved AHR, while wall thickness was not predictive. A logistic regression model combining RV-LV delay and time to peak contraction was able to predict positive response with 70 ± 11% accuracy and AUROC curve of 0.73. Conclusion Non-invasive electrical and mechanical indices can predict optimal epicardial lead location. Prospective analysis of these indices could allow clinicians to test the AHR at fewer pacing sites and reduce time, costs and risks to patients.

Cardiac resynchronization therapy (CRT) is an effective treatment for heart failure patients. Suboptimal pacing timings and locations have been identified as causes for nonresponse to CRT. Patient specific computer models allow for the prediction of the electrical activation pattern on the ventricles, which can then be used to optimise CRT lead location. The electrical activation of the heart depends on the underlying cardiac substrate. The electrical properties of the heart have been found to be heterogeneous, with scar, functional block, septal slowing, and fast endocardial conduction impacting the electrical activation across the ventricles. Non-Invasive data from 14 patients were used to create computer models of the heart. The patient specific models were then used to assess the importance of the heterogeneous cardiac substrates on accurately predicting the electrical activation pattern of the ventricles. Fast endocardial conduction was found to be the most important factor in accurately predicting the electrical activation of the heart in CRT patients.

Background AtrioVentricular (AV) and InterVentricular (VV) delay optimization can improve ventricular function in Cardiac Resynchronization Therapy (CRT) and is usually performed by means of echocardiography. St Jude Medical has developed an automated algorhythm which calculates the optimal AV and VV delays (QuickOpt™) based on Intracardiac ElectroGrams, (IEGM), within 2 min. So far, the efficacy of the algorhythm has been tested acutely with standard lead position at right ventricular (RV) apex. Aim of this project is to evaluate the algorhythm performance in the mid- and long-term with RV lead located in mid-septum. Methods AV and VV delays optimization data were collected in 13 centers using both echocardiographic and QuickOpt™ guidance in CRTD implanted patients provided with this algorhythm. Measurements of the aortic Velocity Time Integral (aVTI) were performed with both methods in a random order at pre-discharge, 6-month and 12-month follow-up. Results Fifty-three patients were studied (46 males; age 68 ± 10y; EF 28 ± 7%). Maximum aVTI obtained by echocardiography at different AV delays, were compared with aVTI acquired at AV delays suggested by QuickOpt. The AV Pearson correlations were 0.96 at pre-discharge, 0.95 and 0,98 at 6- and 12- month follow-up respectively. After programming optimal AV, the same approach was used to compare echocardiographic aVTI with aVTI corresponding to the VV values provided by QuickOpt. The VV Pearson Correlation were 0,92 at pre-discharge, 0,88 and 0.90 at 6-month and 12- month follow-up respectively. Conclusions IEGM-based optimization provides comparable results with echocardiographic method (maximum aVTI) used as reference with mid-septum RV lead location.

Background The impact of right ventricular (RV) lead location on clinical end points in patients undergoing cardiac resynchronization therapy (CRT) is unclear. We evaluated the impact of different RV lead locations on clinical outcome in CRT patients enrolled in the Septal Positioning of ventricular implantable cardioverter-defibrillator (ICD) Electrodes (SPICE) trial, which randomized recipients of implantable cardioverter defibrillators to apical versus midseptal RV lead positioning. Methods Ninety-eight CRT recipients were included in the multicenter SPICE trial and followed for 12 months: Fifty-three patients were randomized to receive an apical (A) and 45 to receive a midseptal (S) lead position. We compared echocardiographical and electrocardiographical parameters and outcome. Results Echocardiographic response with respect to improvement of left ventricular ejection fraction (A: +15.8 ± 14.6%, S: +9.7 ± 12.6%, P = 0.156) and reduction of left ventricular end-diastolic diameter (A: −4.2 ± 10.7 mm, S: −7.5 ± 10.7 mm, P = 0.141) was comparable in apical and midseptal groups. Paced QRS width neither differed at prehospital discharge (A: 129 ± 21 ms, S: 135 ± 21 ms, P = 0.133) nor at 12-month follow-up (A: 131 ± 23 ms, S: 134 ± 28 ms, P = 0.620). No differences were found with respect to the risk of ventricular tachyarrhythmia or ICD therapy. Septal RV lead position, however, was associated with a significant longer time to a first heart failure event (P = 0.040) and a longer survival time (P = 0.019). Conclusions In CRT recipients, midseptal RV lead position was not superior with respect to improvement of echocardiographic parameters or paced QRS width. It did not predispose to ventricular arrhythmias or ICD therapy. The finding that midseptal lead position was associated with a longer time to first heart failure event and a longer survival time deserves further investigation.

Proven to be a successful treatment modality for several chronic pain conditions including Failed Back Surgery Syndrome, spinal cord stimulation (SCS) has many benefits as both a cost-effective and reversible technique. Prior to permanent implantation technique of the device, trial placement is performed to establish expected benefit. Lead location, stimulation parameters, and power source selection are optimized on a case-by-case basis. A recent addition to the growing field of neuromodulation, SCS is a promising new technology with many additional applications yet to be fully elucidated.

We assessed variations in sacral anatomy and lead placement as predictors of sacral neuromodulation (SNM) success. Based solely on bony landmarks, we also assessed the accuracy of the 9 and 2 protocol for locating S3. This is a retrospective cohort study performed from October 2008 to December 2016 at the University of North Carolina at Chapel Hill. Fluoroscopic images were used to assess sacral anatomy and lead location. Success was defined as >50% symptom improvement after stage I and clinical response at most recent follow-up. Of 249 procedures, 209 were primary implants and 40 were revisions among 187 (89.5%) women and 22 (10.5%) men. Success rate was 83.3% for primary implants and 89.4% for revisions. Success was associated with shorter implant duration (21.3 ± 22.2 vs 33.6 ± 25.8 months), higher body mass index (30.3 ± 7.8 vs 27.6 ± 6.1 kg/m2), and straight vs curved lead (90.5% vs 80.5%) (all p = .05), but not with sacral anatomy or lead placement. In assessing the 9 and 2 protocol, mean distance from coccyx to S3 did not equal 9 cm: 7.4 ± 1.0 vs 7.2 ± 0.8 cm (p = .26), while mean distance from midline to S3 did equal 2 cm: 1.9 ± 0.4 vs 2.0 ± 0.7 cm (p = .37). Variations in sacral anatomy and lead placement did not predict SNM success. The 2-cm protocol was verified while the 9-cm protocol was not, although neither was predictive of success, which may obviate the need to mark bony landmarks prior to fluoroscopy.

We report the observed bifurcation in extraordinary electroconductance (EEC) sensor response to direct reverse bias based on measurement lead location as well as a dramatic enhancement in responsivity achieved via a modification of the shunt geometry. A maximum percent change in the four-point resistance of 130856% was achieved under a direct reverse bias of −1 V using an enhanced shunt design, a 325 fold increase over the conventional EEC square shunt design. This result was accompanied by an observed bifurcation in sensor response, driven by a rotation of the four-point measurement leads.

Functional and stereotactic neurosurgery has always been regarded as a subspecialty based on and driven by technological advances. However until recently, the fundamentals of deep brain stimulation (DBS) hardware and software design had largely remained stagnant since its inception almost three decades ago. Recent improved understanding of disease processes in movement disorders as well clinician and patient demands has resulted in new avenues of development for DBS technology. This review describes new advances both related to hardware and software for neuromodulation. New electrode designs with segmented contacts now enable sophisticated shaping and sculpting of the field of stimulation, potentially allowing multi-target stimulation and avoidance of side effects. To avoid lengthy programming sessions utilising multiple lead contacts, new user-friendly software allows for computational modelling and individualised directed programming. Therapy delivery is being improved with the next generation of smaller profile, longer-lasting, re-chargeable implantable pulse generators (IPGs). These include IPGs capable of delivering constant current stimulation or personalised closed-loop adaptive stimulation. Post-implantation Magnetic Resonance Imaging (MRI) has long been an issue which has been partially overcome with 'MRI conditional devices' and has enabled verification of DBS lead location. Surgical technique is considering a shift from frame-based to frameless stereotaxy or greater role for robot assisted implantation. The challenge for these contemporary techniques however, will be in demonstrating equivalent safety and accuracy to conventional methods. We also discuss potential future direction utilising wireless technology allowing for miniaturisation of hardware.

BACKGROUND: Magnetic resonance imaging (MRI)-verified deep brain stimulation relies on the correct interpretation of stereotactic imaging documenting lead location in relation to visible anatomic target. However, it has been suggested that local signal distortion from the lead itself renders its depiction on MRI unreliable. OBJECTIVE: To compare lead location on stereotactic MRI with subsequent location of its brain track after removal. METHODS: Patients underwent deep brain stimulation with the use of MRI-guided and MRI-verified Leksell frame approach. Infection or suboptimal efficacy required lead removal and subsequent reimplantation by using the same technique. Postimplantation stereotactic MR images were analyzed. Lateral (x) and anteroposterior (y) distances from midcommissural point to center of the lead hypointensity were recorded at the anterior commissure-posterior commissure plane (pallidal electrode) or z = 24 (subthalamic electrode). Stereotactic MRI before the second procedure, x and y distances from the center of the visible lead track hypointensity to midcommissural point were independently recorded. Vectorial distance from center of the lead hypointensity to the center of its track was calculated. RESULTS: Sixteen electrode tracks were studied in 10 patients. Mean differences between lead artifact location and lead track location were: x coordinate 0.4 mm +/- 0.2; y coordinate 0.6 mm +/- 0.3. Mean vectorial distance was 0.7 mm +/- 0.2. CONCLUSION: Stereotactic distance between lead location and subsequent brain track location on MRI was small. The mean discrepancy was approximately half the deep brain stimulation lead width. This suggests that lead hypointensity seen on postimplantation MRI is indeed an accurate representation of its real location within deep brain structures.

The effects of right ventricular (RV) lead location and the combination of RV and left ventricular (LV) lead locations on long-term outcomes in patients receiving cardiac resynchronization therapy with defibrillator (CRT-D) are not well understood. Our cohort consisted of 743 CRT-D patients from MADIT-CRT. We evaluated long-term death and combined heart failure or death (HF/death) in patients with non-apical RV vs. apical RV leads. We further assessed these long-term outcomes based on the combination of RV and LV leads, termed “RV-LV lead interaction.” Patients with non-apical RV and apical LV leads and those with apical RV and non-apical LV leads were described to have “discordant RV and LV leads.” Patients with RV and LV leads that were both non-apical or both apical were defined to have “concordant RV and LV leads.” There were no differences in death and HF/death between patients with non-apical RV vs. apical RV leads. However, patients with non-apical RV and apical LV leads had higher mortality risk, relative to those with apical RV and non-apical LV leads (HR = 4.06, 95% CI 1.73–9.53, p = 0.001) as well as those with both leads in the non-apical (HR = 3.82, 95% CI 1.33–10.98, p = 0.013) or apical (HR = 3.40, 95% CI 1.24–9.37, p = 0.018) positions. There was no difference in HF/death by RV-LV lead sub-groups. Among CRT-D patients, long-term outcomes were similar for non-apical RV and apical RV leads. However, mortality risk was increased with discordant RV and LV leads, when a non-apical RV lead was combined with an apical LV lead.

IntroductionPallidal deep brain stimulation (GPi-DBS) is an effective therapy for isolated dystonia, but 10–20% of patients show improvement below 25–30%. We here investigated causes of insufficient response to GPi-DBS in isolated dystonia in a cross-sectional study.MethodsPatients with isolated dystonia at time of surgery, and

Personalised cardiac models were built from the computed tomography imaging data for two patients with implanted cardiac resynchronisation therapy devices. The cardiac models comprised a biventricular model of myocardial electrophysiology coupled with a model of the torso to simulate the body surface potential map. The models were verified against electrocardiogams (ECG) recorded in the patients from 240 leads on the body surface under left ventricular pacing. The simulated ECG demonstrated a significant sensitivity to the myocardial anisotropy and location of the pacing electrode tip in the models. An apicobasal cellular heterogeneity was shown to be less significant for the ECG pattern at the paced-ventricle activation than that showed earlier by Keller and co-authors (2012) for the normal activation sequence. © 2017 IEEE Computer Society. All rights reserved. This study was supported by the RAS Presidium Programme I.33Π, and Government of the Russian Federation (agreement 02.A03.21.0006). We used the computational clusters of Ural Federal University and ”URAN” of Institute of Mathematics and Mechanics (Ekaterinburg).

Up to one-third of patients who undergo cardiac resynchronisation therapy (CRT) are not responders. To identify potential responders to CRT may be sometimes difficult and time-consuming. Forty-five patients who had undergone CRT implantation for standard indications were evaluated. Electrical left ventricular (LV) lead location was assessed by left ventricular activation time (LVAT), LV lead electrical delay (LVLED), and RV-LV interlead electrical delay (RVsense-LVsense). Anatomic LV pacing location was assessed as basal or mid-ventricular between 3:00 to 5:00 (traditionally optimal site), and all the other positions (traditionally non-optimal site). CRT response was defined as a decrease in LV end-systolic volume (LVESV) exceeding 15% at six months. LVLED was larger in the responder group than that in the non-responder group (67.3 ± 8.5% vs. 55.3 ± 8.1%, P0.001). In the multivariate analysis, LVLED and cLBBB morphology were the two independent predictors of positive echocardiographic response to CRT (OR=1.180, P=0.003; OR=7.497, P=0.04, respectively). A cutoff value of LVLED54.82% predicted responders with 96.3% sensitivity and 75.2% specificity and the area under the receiver operating characteristic (ROC) curve was 0.844 for LVLED (P=0.002). No relationship was found between the anatomic LV pacing sites and response to CRT (P=0.188). The larger left ventricular lead electrical delay may predict response to cardiac resynchronisation therapy.

ObjectivesTo quantify the accuracy of DBS electrode implantation for movement disorder in paediatric patients utilising the neuroinspire™ software and neuromate® robot.DesignRetrospective, single-centre, cohort study.SubjectsFifteen patients with dystonia (67% female; median age 11 years, range 8–18 years) underwent intervention since May 2017.MethodsDBS procedures were planned on the neuroinspire™ software and electrodes were implanted using the Renishaw neuromate® robot and Renishaw guide tubes and secured with a dog-bone plate under general anaesthetic. Post-operative CT imaging with the intra-operative O-arm was fused to pre-operative imaging. Planned entry and target coordinates were compared to actual entry and final target coordinates in order to obtain absolute and directional errors in x (medial-lateral), y (anterior-posterior) and z (dorsal-ventral) planes. Euclidean error was calculated for each electrode. Wilcoxon signed-rank test was used to analyse error.ResultsBilateral GPi were targeted and Medtronic DBS systems were implanted for each patient (n=30). Overall median Euclidean error for electrode implantation was 2.13 mm (range, 0.71–4.85; pConclusionsWe observed an improvement in the discrepancy seen between planned and actual lead location compared to a previously reported series using the Leksell frame in a similar cohort. Addressing possible compounding factors such as drilling techniques and electrode fixation should increase accuracy further. The neuromate® Robot is a reliable and accurate alternative to the Leksell frame.

Background Post-traumatic tremor is one of the most common movement disorders resulting from severe head trauma. However, literature regarding successful deep brain stimulation (DBS) treatment is scarce, resulting in ambiguity regarding the optimal lead location. Most cases support the ventral intermediate nucleus, but there is evidence to defend DBS of the zona incerta, ventral oralis anterior/posterior, and/or a combination of these targets. We report five patients with disabling post-traumatic tremor treated with DBS of the ventral intermediate nucleus and of the globus pallidus internus. Methods Patients were referred to the Vanderbilt Movement Disorders Division, and surgical intervention was determined by a DBS Multidisciplinary Committee. Standard DBS procedure was followed. Results Patients 1–4 sustained severe diffuse axonal injuries. Patients 1–3 underwent unilateral ventral intermediate nucleus DBS for contralateral tremor, while Patient 4 underwent bilateral ventral intermediate nucleus DBS. Patients 1–3 experienced good tremor reduction, while Patient 4 experienced moderate tremor reduction with some dystonic posturing of the hands. Patient 5 had dystonic posturing of the right upper extremity with tremor of the left upper extremity. He was treated with bilateral DBS of the globus pallidus internus and showed good tremor reduction at follow-up. Conclusion Unilateral or bilateral DBS of the ventral intermediate nucleus and bilateral DBS of the globus pallidus internus may be effective and safe treatment modalities for intractable post-traumatic tremor. Further studies are needed to clarify the optimal target for surgical treatment of post-traumatic tremor.

Aims Right ventricular apical pacing has a detrimental effect on left ventricular (LV) function. More optimal pacing site may be found by invasive measurement of LV mechanical performance during pacing from different RV pacing sites. We aimed to investigate the effect of RV pacing lead location on invasive indices of LV mechanical performance. Methods and results Patients undergoing catheter ablation for persistent atrial fibrillation were enrolled. Single-site endocardial pacing from the lateral LV region was periodically switched to pacing from the mapping catheter navigated to different RV sites within the three-dimensional electroanatomical RV map. SystIndex, DiastIndex, and PPIndex were defined as the ratio of LV d P /d t max, LV d P /d t min, and arterial pulse pressure during RV pacing to corresponding values from adjacent periods of LV pacing. Haemodynamic data were analysed in 18 RV segments created by dividing RV horizontally (basal, mid, and apical portion), vertically (inferior, mid, and superior portion) and frontally (septum and free wall). Eight patients (58 ± 7 years; 2 females; 26 ± 4 RV pacing sites per patient) were enrolled into the study. Compared with LV pacing, the best RV pacing values of SystIndex and DiastIndex were achieved in basal-mid-septal segment (+6.9%, P = 0.02 and +3.4%, P = 0.36, respectively) while the best PPIndex was obtained in superior-mid-septal segment of RV (+4.5%, P = 0.02). All indices were fairly concordant showing significant improvement of haemodynamics during RV pacing in the direction from free wall to septum, from apex to base, and from inferior to superior segments. Conclusion The best LV mechanical performance was achieved by RV septal pacing in the non-apical mid-to-superior segments.

Objectives: Interpreting the postoperative electroencephalographic (EEG) driving response (DR) as an indicator of electrode placement within the thalamic nucleus in deep brain stimulation (DBS) of the anterior nucleus of the thalamus (ANT) for refractory epilepsy is controversial. Materials and Methods: We retrospectively investigated the relationship between postoperative EEG DR and the location of 11 electrodes in 6 patients who underwent ANT DBS for refractory epilepsy. Results: Cerebral synchronizing EEG DR was observed in 10 electrodes. However, 9 of the 11 electrodes were located within the ANT. For the 2 electrodes that missed the ANT, DR was observed in 1 misplaced electrode facing the anterior surface of the ANT within the third ventricle. The other misplaced electrode without DR elicitation showed a DR after electrode repositioning. Conclusions: The diagnostic significance of DR as indirect evidence of electrodes being within thalamic nuclei is limited. If DR is not elicited, it should be regarded as a misplacement. Even if DR is elicited, it may not be interpreted as a sound indicator of proper electrode placement within the thalamus. A sophisticated, postoperative imaging study is warranted in every case of ANT DBS.

An early repolarization (ER) pattern in the ECG, distinguished by J-point elevation, slurring of the terminal part of the QRS and ST-segment elevation has long been recognized and considered to be a benign electrocardiographic manifestation. Experimental studies conducted over a decade ago suggested that some cases of ER may be associated with malignant arrhythmias. Validation of this hypothesis was provided by recent studies demonstrating that an ER pattern in the inferior or inferolateral leads is associated with increased risk for life-threatening arrhythmias, termed ER syndrome (ERS). Because accentuated J waves characterize both Brugada syndrome (BS) and ERS, these syndromes have been grouped under the term "J wave syndromes". ERS and BS share similar ECG characteristics, clinical outcomes and risk factors, as well as a common arrhythmic platform related to amplification of Ito-mediated J waves. Although BS and ERS differ with respect to the magnitude and lead location of abnormal J wave manifestation, they can be considered to represent a continuous spectrum of phenotypic expression. Although most subjects exhibiting an ER pattern are at minimal to no risk, mounting evidence suggests that careful attention should be paid to subjects with "high risk" ER. The challenge ahead is to be able to identify those at risk for sudden cardiac death. Here I review the clinical and genetic aspects as well as the cellular and molecular mechanisms underlying the J wave syndromes. (Circ J 2012; 76: 1054-1065)

The advantages of triple-site ventricular pacing (Tri-V) compared to conventional biventricular site pacing (Bi-V) have been reported. We sought to identify the predictors of acute hemodynamic Tri-V responders. Acute hemodynamic studies were performed in 32 patients with advanced heart failure during Tri-V implantation. After the right ventricular (RV) and left ventricular (LV) leads were implanted for a conventional Bi-V system, an additional pacing lead was implanted in the RV outflow tract for Tri-V. The LV peak +dP/dt and tau were measured during AAI, Bi-V, and Tri-V pacing. A Tri-V responder was defined as a patient whose percentage of increase in the peak +dP/dt during Tri-V was >10% compared to of that during Bi-V. The baseline clinical variables and RV outflow tract lead location were analyzed to identify the characteristics of the Tri-V responders. Of the 32 patients, 10 (31%) were classified as Tri-V responders. The LV end-diastolic volume was greater (246 ± 48 vs 173 ± 53 ml, p 212 ml had a sensitivity of 80% and specificity of 77% to distinguish Tri-V responders. In conclusion, Tri-V provides greater hemodynamic effect for patients with a larger LV end-diastolic volume owing to its resynchronization effects on the LV anterior wall.

The combined effects of cardiac anatomy and pacing lead electrode location within left ventricular cardiac veins on resultant pacing thresholds are not well understood. The specific aims of this study were to: (1) develop a comparative electrostatic model based on previously obtained histological measurements, and (2) compare resulting electric fields and voltage gradients with in vitro experimental results. In vitro pacing thresholds measured from swine hearts were utilized to model electric fields generated from different cardiac venous pacing locations within veins of varying diameter and fat thickness. The simulated activation fields were defined as 100 V/m and all materials were defined as isotropic. The obtained results predicted larger activation fields when an electrode was oriented away from the myocardium or in free-floating positions, hence requiring more myocardial tissue to have 100 V/m than when it was oriented toward the myocardium. Thus, the resultant modeled electric fields followed the same qualitative trends as in vitro experiments performed in the swine hearts. In general, while electrode position primarily affected pacing thresholds, both vein diameter and relative epicardial fat thickness also influenced pacing thresholds. The electric fields were larger for basal regions modeled using larger vein diameters and epicardial fat thicknesses. These electrostatic field simulations provide unique insights as to how varied cardiac anatomies and relative electrode locations affect thresholds by enabling visualization of the electric fields propagating through cardiac tissues during pacing from the venous system.

Introduction: Left ventricular (LV) lead placement to the latest contracting area (concordant LV lead) is associated with better response to cardiac resynchronization therapy (CRT) compared to a discordant LV lead. However, the effect of the right ventricular (RV) lead site on CRT response is unclear. We investigated the relationship of the RV and LV lead positions on CRT response. Methods: In 131 CRT patients, the LV lead was positioned preferentially in a lateral or posterolateral vein and the RV lead to either the RV septum (RVS, n = 55) or RV apex (RVA, n = 76). The latest site of contraction was determined with two-dimensional speckle tracking radial strain imaging and patients had a concordant LV lead position if pacing the latest segment, and discordant if not. Response was defined as ≥15% reduction in LV end systolic volume (LVESV) at 6-month follow-up. Results: There were no significant differences in mean reduction of LVESV at follow-up (RVS vs RVA: −23.3 ± 16% vs 22.1 ± 18%, P = 0.70) or rate of responders (58.2% vs 57.9%, P = 0.97) between the two groups. In patients with a concordant LV lead (n = 71), the response rate was significantly higher than those with a discordant lead (76.1% vs 36.7%, P < 0.001). There were no differences in outcomes in patients with a concordant or discordant LV lead according to the RV lead location. Conclusion: The extent of LV reverse remodeling following CRT is not related to the RV lead position, but is significantly higher in patients with a concordant LV lead. (PACE 2011; 34:467–474)

Magnetic resonance imaging (MRI) is a commonly used and important imaging modality to evaluate lead location and rule out complications after deep brain stimulation (DBS) surgery. Recent safety concerns have prompted new safety recommendations for the use of MRI in these patients, including a new recommendation to limit the specific absorption rate (SAR) of the MRI sequences used to less than 0.1 W/kg. Following SAR recommendations in real-world situations is problematic for a variety of reasons. We review our experience scanning patients with implanted DBS systems over a 7-year period using a variety of scanning techniques and four scanning platforms. 405 patients with 746 implanted DBS systems were imaged using 1.5-tesla MRI with an SAR of up to 3 W/kg. Many of the DBS systems were imaged multiple times, for a total of 1,071 MRI events in this group of patients with no adverse events. This series strongly suggests that the 0.1 W/kg recommendation for SAR may be unnecessarily low for the prevention of MRI-related adverse events.

The targeting and implantation of deep brain stimulation (DBS) electrodes traditionally is based on the interpretation of preoperative MRI, with most centers employing intraoperative electrophysiological recordings to verify actual lead location. Recent advances in real-time MRI guidance, however, are changing this paradigm. This chapter addresses advances in image guidance for functional neurosurgery in three important areas: (1) optimization of preoperative techniques for visualizing the target structure and related tractography to optimize target selection in DBS, (2) development of interventional-MRI (iMRI) for real-time visualization of DBS electrode placement in MRI-visible anatomic targets, and (3) the development of iMRI gene therapy delivery strategies for the treatment of Parkinson’s disease.

Dear Editor,Our prior correspondence has already addressed the Romegroup’s perceived concerns about lead location vis-a-vis thepedunculopontinenucleus(PPN)andpontinemicturitioncen-tre (PMC), the size of the MRI artefact generated by theimplanted lead and the suitability of our patient for PPN deepbrain stimulation (DBS) [2, 10]. We agree that friendly dis-cussionpromotesscientificdebate.However,itshouldalsoberecognisedthatwild speculation and inaccuratestatements donot make a positive contribution. The Rome group does notthink it made wild speculations. Nevertheless, they made aspeculativeandincorrectassumptionthatweusealargemetalcannula despite the fact that we never use any cannula duringDBS surgery [7, 10].Wefailtounderstandwhyanyonewould“keepwondering(why) the electrode artefact … is larger than the aqueduct”.We reiterate that the size of the lead artefact on MRI dependsonseveralfactors,includingtheparticularMRIsequenceusedduring imaging [18].Notwithstanding the Rome group’s conjecture, we arefully aware of the published literature on somatosensoryevoked potentials (SEPs) and the PPN. Within that bodyof work, the Rome group states: “P16 potentials recorded bythe intracranial electrode contacts are generated by the vol-ley travelling along the medial lemniscus” [1]. We againassert that a lead lying within, or lateral to, the mediallemniscus would still be expected to record such SEPs.Contrary to their belief, “electrophysiological recordingsand functional evaluations” do not provide accurate anatom-ical information on lead location. This is especially true of anovel target where such surrogate markers are relativelypoorly defined in relation to anatomical location. Accurateinterpretation of stereotactic MRI currently provides themost reliable method of assessing the anatomical locationof implanted leads in patients.It was the correspondence from Rome that re-introducedthe topic of accurate lead location within the PPN. Yet,we are reproached for “exhumation of an already burieddispute”. Furthermore, inaccuracy of anatomical fact persistsin their recent correspondence. Contrary to their description,the rostrocaudal extent of the PPN straddles the pontomesen-cephalic junction (PMJ) and is not confined inferior to thePMJ [14, 15].Another group has also noted that: “in the study byStefani et al., electrodes were lateral to the medial lemniscus”[5]. Nevertheless, when referring to their own postoperativeMRI, the Rome group does “not understand … the claim that(their) electrode was placedlaterally to the lateral lemniscus”.To facilitate this understanding, their own published MRI isnow reproduced in the accompanying figure, together with asummary of the radiological anatomy of the PPN (Fig. 1).

“It has long been an axiom of mine that the little things are infinitely the most important” — —Sherlock Holmes in “A Case of Identity” by Arthur Conan Doyle Cardiac resynchronization therapy (CRT) can have a profound therapeutic impact on appropriately selected patients. However, even when the current clinical guidelines for CRT1 are rigorously applied, the response rate is ≈70%. Nearly a third of patients who undergo implantation of a CRT device are clinical nonresponders and more may be “remodeling nonresponders.” An extensive body of literature reports on a wide variety of methods that can be better used to identify potential responders by measurement of mechanical dyssynchrony. Factors responsible for nonresponse include comorbid conditions, cardiac substrate, left ventricular (LV) lead location, and device programming. Comorbid conditions such as obstructive sleep apnea, right-sided heart failure, and type of intraventricular conduction delay should be considered at the preprocedural stage. Device programming may help minimize the number of nonresponders. Prediction of responders by invasive hemodynamic assessment is impractical for daily clinical practice. Cardiac magnetic resonance imaging is too expensive for routine use and is not an option for many patients who already have devices and need upgrades. The appeal of echocardiography for predicting responders by identifying mechanical dyssynchrony has been dampened by its limited reproducibility and poor predictive value.2 It is also impractical to perform echocardiography during implantations. The prolonged QRS duration (QRSd; electric dyssynchrony), as measured on a standard 12-lead ECG, remains the best method for identifying candidates for CRT. In an elegant and important study reported in this issue of Circulation , Sweeney and colleagues3 use the 12-lead ECG and show that, despite its apparent simplicity, analysis of the standard 12-lead ECG can yield both pitfalls and impressive rewards. Article see p 626 Current clinical guidelines specify a …

Comment on "Appropriate MRI sequences are required to accurately determine lead location after deep brain stimulation surgery"

Lead placement in cardiac resynchronization therapy (CRT) has been identified as an important variable that can potentially be manipulated at the time of implantation. Recent studies have demonstrated the variability of the acute hemodynamic response of patients to different lead positions and have proposed different strategies to identify the optimal lead location. In clinical studies of lead position the maximum rate of pressure development is used as a single scalar measure of the efficacy of an individual pacing location, despite limited clinical evidence that this correlates with long term outcomes. In this study, we use a patient-specific computational model to evaluate metrics of cardiac function for different lead positions. The model predicts a large, common, optimal location for all evaluated metrics. This supports use of the maximum rate of pressure development as a representation of general cardiac function for optimizing CRT.

Introduction: Deep brain stimulation is the most frequently performed neurosurgical procedure for movement disorders. This procedure is well tolerated, but not free of complications. Analysis of hardware complications based on patient diagnosis and lead location could prove valuable in recognizing potential pitfalls and patients at higher risk. Methods: This review analyzes the most common surgery-related complications that may occur based on diagnosis and lead location. Patients were categorized based on diagnosis – Parkinson’s disease (PD), dystonia, and essential tremor (ET) – as well as by lead location – subthalamic nucleus (STN), globus pallidus interna (GPi), and ventral intermediate nucleus of the thalamus (Vim). It is a retrospective review of 326 patients undergoing 949 procedures over a 10-year period by one surgeon. Fisher’s exact test and χ2 test were employed and multivariate logistic regression analysis was performed to identify the significant variables of correlation. Results: Overall lead revision was observed at 5.7%, but was observed at 11.9% of GPi lead placements, and 10.7% of dystonia patients with only 4.6% of STN lead placements. Total extension revision was at 2.5%, but observed at 5.3% for dystonia patients and at only 1.4% for ET patients. Overall infection rate was at 1.9% with the highest rate observed in dystonia and ET patients. Postoperative complications with hardware, erosion, infection, and delayed stimulation failure were observed more often with ET and dystonia than with PD. This difference was statistically significant between dystonia and PD (p < 0.03) but not between the other disease entities (p > 0.05). On multivariate analysis, age and gender had no correlation with these complications. PD had significantly fewer complications on forward selection regression analysis (p = 0.004). Asymptomatic intracerebral hemorrhage was at 2.5% with the majority in Vim and none observed in GPi placements. There was only one symptomatic hemorrhage with a permanent deficit. Infarcts were observed at 0.8%. There were no mortalities. Conclusion: This large series of patients and long-term follow-up demonstrate that risks of complications are not universal among movement disorder patients. Diagnosis and lead location are important risk stratification factors in determining complications.

Object Correct lead location in the desired target has been proven to be a strong influential factor for good clinical outcome in deep brain stimulation (DBS) surgery. Commonly, a surgeon's first reliable assessment of such location is made on postoperative imaging. While intraoperative CT (iCT) and intraoperative MR imaging have been previously described, the authors present a series of frameless DBS procedures using O-arm iCT. Methods Twelve consecutive patients with 15 leads underwent frameless DBS placement using electrophysiological testing and O-arm iCT. Initial target coordinates were made using standard indirect and direct assessment. Microelectrode recording (MER) with kinesthetic responses was performed, followed by microstimulation to evaluate the side-effect profile. Intraoperative 3D CT acquisitions obtained between each MER pass and after final lead placement were fused with the preoperative MR image to verify intended MER movements around the target area and to identify the final lead location. Tip coordinates from the initial plan, final intended target, and actual lead location on iCT were later compared with the lead location on postoperative MR imaging, and euclidean distances were calculated. The amount of radiation exposure during each procedure was calculated and compared with the estimated radiation exposure if iCT was not performed. Results The mean euclidean distances between the coordinates for the initial plan, final intended target, and actual lead on iCT compared with the lead coordinates on postoperative MR imaging were 3.04 ± 1.45 mm (p = 0.0001), 2.62 ± 1.50 mm (p = 0.0001), and 1.52 ± 1.78 mm (p = 0.0052), respectively. The authors obtained good merging error during image fusion, and postoperative brain shift was minimal. The actual radiation exposure from iCT was invariably less than estimates of exposure using standard lateral fluoroscopy and anteroposterior radiographs (p < 0.0001). Conclusions O-arm iCT may be useful in frameless DBS surgery to approximate microelectrode or lead locations intraoperatively. Intraoperative CT, however, may not replace fundamental DBS surgical techniques such as electrophysiological testing in movement disorder surgery. Despite the lack of evidence for brain shift from the procedure, iCT-measured coordinates were statistically different from those obtained postoperatively, probably indicating image merging inaccuracy and the difficulties in accurately denoting lead location. Therefore, electrophysiological testing may truly be the only means of precisely knowing the location in 3D space intraoperatively. While iCT may provide clues to electrode or lead location during the procedure, its true utility may be in DBS procedures targeting areas where electrophysiology is less useful. The use of iCT appears to reduce radiation exposure compared with the authors' traditional frameless technique.