Three Levels of Neural Control Contributing to Performance-stabilizing Synergies in Multi-finger Tasks.

We tested a hypothesis on force-stabilizing synergies during four-finger accurate force production at three levels: (1) The level of the reciprocal and coactivation commands, estimated as the referent coordinate and apparent stiffness of all four fingers combined; (2) The level of individual finger forces; and (3) The level of firing of individual motor units (MU). Young, healthy participants performed accurate four-finger force production at a comfortable, non-fatiguing level under visual feedback on the total force magnitude. Mechanical reflections of the reciprocal and coactivation commands were estimated using small, smooth finger perturbations applied by the "inverse piano" device. Firing frequencies of motor units in the flexor digitorum superficialis (FDS) and extensor digitorum communis (EDC) were estimated using surface recording. Principal component analysis was used to identify robust MU groups (MU-modes) with parallel changes in the firing frequency. The framework of the uncontrolled manifold hypothesis was used to compute synergy indices in the spaces of referent coordinate and apparent stiffness, finger forces, and MU-mode magnitudes. Force-stabilizing synergies were seen at all three levels. They were present in the MU-mode spaces defined for MUs in FDS, in EDC, and pooled over both muscles. No effects of hand dominance were seen. The synergy indices defined at different levels of analysis showed no correlations across the participants. The findings are interpreted within the theory of control with spatial referent coordinates for the effectors. We conclude that force stabilization gets contributions from three levels of neural control, likely associated with cortical, subcortical, and spinal circuitry.

Force matching: motor effects that are not reported by the actor.

We explored unintentional drifts of finger forces during force production and matching task. Based on earlier studies, we predicted that force matching with the other hand would reduce or stop the force drift in instructed fingers while uninstructed (enslaved) fingers remain unaffected. Twelve young, healthy, right-handed participants performed two types of tasks with both hands (task hand and match hand). The task hand produced constant force at 20% of MVC level with the Index and Ring fingers pressing in parallel on strain gauge force sensors. The Middle finger force wasn't instructed, and its enslaved force was recorded. Visual feedback on the total force by the instructed fingers was either present throughout the trial or only during the first 5 s (no-feedback condition). The other hand matched the perceived force level of the task hand starting at either 4, 8, or 15 s from the trial initiation. No feedback was ever provided for the match hand force. After the visual feedback was removed, the task hand showed a consistent drift to lower magnitudes of total force. Contrary to our prediction, over all conditions, force matching caused a brief acceleration of force drift in the task hand, which then reached a plateau. There was no effect of matching on drifts in enslaved finger force. We interpret the force drifts within the theory of control with spatial referent coordinates as consequences of drifts in the command (referent coordinate) to the antagonist muscles. This command is not adequately incorporated into force perception.

Prospective, Multi-center, Single-Arm Study of the Auryon Laser System for Treatment of Below-the-Knee Arteries in Patients With Chronic Limb-Threatening Ischemia: 30-Day Results of the Auryon BTK.

The 355 nm Auryon laser (AngioDynamics, Inc., Latham, New York) has been shown to be effective and safe in treating various morphology lesions in the femoropopliteal arteries. There are limited data on the Auryon laser in treating below-the-knee (BTK) arteries in patients with chronic limb-threatening ischemia. We present the 30-day efficacy and safety findings from the ongoing Auryon BTK study. Patients with chronic limb-threatening ischemia were prospectively enrolled in the Auryon BTK study between March 2022 and February 2023 in 4 US centers after obtaining written informed consent. The primary safety end point included major adverse limb events + postoperative death at 30 days, defined as a composite of all-cause death, major amputation, and target vessel revascularization. Demographic, procedural, angiographic, and outcome data were collected. A total of 60 patients (61 lesions) were treated. The mean age was 74.6 ± 10.3 years, with 65.0% men, 58.3% with diabetes, 43.3% Rutherford Becker (RB) IV, and 56.7% RB V. Of the 61 lesions, 59% had severe calcification, 31.1% were chronic total occlusions, and 90.2% were de novo disease. The baseline diameter stenosis was 80.2 ± 16.4%, after laser 57.4 ± 21.7%, and after final treatment 24.0 ± 23.1% (p <0.0050). The primary performance end point showed a procedure success rate of 37 of 68 (63.8%). Bailout stenting occurred in 1 of 61 lesions (1.6%). The RB category was 100% RB IV or higher at baseline versus 35.3% at 30 days. At 30 days, there was no target vessel revascularization and the patency was 88.9% (Peak Systolic Velocity Ratio (PSVR) ≤2.4). In conclusion, the Auryon laser is safe and relatively effective in treating BTK lesions with minimal complications.

"TCAR or nothing": the only options for some complex carotid stenosis.

Transcervical carotid artery revascularization has emerged as an alternative to carotid endarterectomy and transfemoral carotid artery stenting. We present four cases for which we believe transcervical carotid artery revascularization was the only option to treat the lesions. Each case presented with specific technical challenges that were overcome by intraoperative planning that allowed for safe deployment of the Enroute stent (Silk Road Medical) with resolution of each patient's stenosis.

Two classes of action-stabilizing synergies reflecting spinal and supraspinal circuitry.

We explored force-stabilizing synergies during accurate four-finger constant force production tasks in spaces of finger modes (commands to fingers computed to account for the finger interdependence) and of motor unit (MU) firing frequencies. The main specific hypothesis was that the multifinger synergies would disappear during unintentional force drifts without visual feedback on the force magnitude, whereas MU-based synergies would be robust to such drifts. Healthy participants performed four-finger accurate cyclical force production trials followed by trials of constant force production. Individual MUs were identified in the flexor digitorum superficialis (FDS) and extensor digitorum communis (EDC). Principal component analysis was applied to motor unit frequencies to identify robust MU groups (MU-modes) with parallel scaling of the firing frequencies in FDS, in EDC, and the combined MUs of FDS + EDC. The framework of the uncontrolled manifold hypothesis was used to quantify force-stabilizing synergies when visual feedback on the force magnitude was available and 15 s after turning the visual feedback off. Removing visual feedback led to a force drift toward lower magnitudes, accompanied by the disappearance of multifinger synergies. In contrast, MU-mode synergies were minimally affected by removing visual feedback off and continued to be robust for the FDS and for the EDC, while being absent for the (FDS + EDC) analysis. We interpret the findings within the theory of hierarchical control of action with spatial referent coordinates. The qualitatively different behavior of the multifinger and MU-mode-based synergies likely reflects the difference in the involved neural circuitry, supraspinal for the former and spinal for the latter.NEW & NOTEWORTHY Two types of synergies, in the space of commands to individual fingers and in the space of motor unit groups, show qualitatively different behaviors during accurate multifinger force-production tasks. After removing visual feedback, finger force synergies disappear, whereas motor unit-based synergies persist. These results point at different neural circuitry involved in these two basic classes of synergies: supraspinal for multieffector synergies, and spinal for motor unit-based synergies.

Effects of fatigue on intramuscle force-stabilizing synergies.

We applied the recently introduced concept of intramuscle synergies in spaces of motor units (MUs) to quantify indexes of such synergies in the tibialis anterior during ankle dorsiflexion force production tasks and their changes with fatigue. We hypothesized that MUs would be organized into robust groups (MU modes), which would covary across trials to stabilize force magnitude, and the indexes of such synergies would drop under fatigue. Healthy, young subjects (n = 15; 8 females) produced cyclical, isometric dorsiflexion forces while surface electromyography was used to identify action potentials of individual MUs. Principal component analysis was used to define MU modes. The framework of the uncontrolled manifold (UCM) was used to analyze intercycle variance and compute the synergy index, ΔVZ. Cyclical force production tasks were repeated after a nonfatiguing exercise (control) and a fatiguing exercise. Across subjects, fatigue led, on average, to a 43% drop in maximal force and fewer identified MUs per subject (29.6 ± 2.1 vs. 32.4 ± 2.1). The first two MU modes accounted for 81.2 ± 0.08% of variance across conditions. Force-stabilizing synergies were present across all conditions and were diminished after fatiguing exercise (1.49 ± 0.40) but not control exercise (1.76 ± 0.75). Decreased stability after fatigue was caused by an increase in the amount of variance orthogonal to the UCM. These findings contrast with earlier studies of multieffector synergies demonstrating increased synergy index under fatigue. We interpret the results as reflections of a drop in the gain of spinal reflex loops under fatigue. The findings corroborate an earlier hypothesis on the spinal nature of intramuscle synergies.NEW & NOTEWORTHY Across multielement force production tasks, fatigue of an element leads to increased indexes of force stability (synergy indexes). Here, however, we show that groups of motor units in the tibialis anterior show decreased indexes of force-stabilizing synergies after fatiguing exercise. These findings align intramuscle synergies with spinal mechanisms, in contrast to the supraspinal control of multimuscle synergies.

Safety and efficacy of the CELT ACD femoral arteriotomy closure device in the office-based laboratory.

Objective: Manual compression remains the gold standard for achieving hemostasis for percutaneous common femoral artery access. However, it requires prolonged bedrest and 20 to 30 minutes or more of compression for hemostasis. Current arterial closure devices have emerged in recent years, but patients still require prolonged bedrest and time to ambulation and discharge, and these devices are associated with significant access device complications, including hematoma, retroperitoneal bleeding, transfusion requirement, pseudoaneurysm, arteriovenous fistula, and arterial thrombosis. A novel femoral access closure device, the CELT ACD (Vasorum Ltd, Dublin, Ireland), has been previously shown to reduce these complication rates and allow rapid hemostasis, require little or no bedrest, and shortened time to ambulation and discharge. This is especially advantageous in the outpatient setting. We report our initial experience with this device. Methods: A prospective single-center single-arm study was performed in an office-based laboratory setting to assess the safety and efficacy of the CELT ACD closure device. Patients underwent diagnostic and therapeutic peripheral arterial procedures from retrograde or antegrade common femoral artery access. Primary endpoints include device deployment success, time to hemostasis, and major or minor complications. Secondary endpoints include time to ambulation and time to discharge. Major complications were defined as bleeding requiring hospitalization or blood transfusion, device embolization, pseudoaneurysm formation, and limb ischemia. Minor complications were defined as bleeding not requiring hospitalization/blood transfusion, device malfunction, and access site infection. Results: A total of 442 patients were enrolled with common femoral access only. Median age was 78 years (range, 48-91 years), and 64% were male. Heparin was given in all cases, with median heparin dose of 6000 units (range, 3000-10,000 units). Protamine reversal was used in 10 cases due to minor soft tissue bleeding. Average time to hemostasis was 12.1 seconds (±13.2 seconds), time to ambulation was 17.1 minutes (±5.2 minutes), and time to discharge was 31.7 minutes (±8.9 minutes). All devices (100%) were deployed successfully. No major complications occurred (0%). Ten minor complications (2.3%) occurred; all were minor soft tissue bleeding from the access site that resolved with protamine reversal of heparin and manual compression. Conclusions: The CELT ACD closure device is safe and easily deployed with a very low complication rate, and significantly reduces time to hemostasis, ambulation, and discharge in patients undergoing peripheral arterial intervention from a common femoral artery approach in the office-based laboratory setting. This is a promising device that deserves further evaluation.

Motor unit-based synergies in a non-compartmentalized muscle.

The concept of synergies has been used to address the grouping of motor elements contributing to a task with the covariation of these elements reflecting task stability. This concept has recently been extended to groups of motor units with parallel scaling of the firing frequencies with possible contributions of intermittent recruitment (MU-modes) in compartmentalized flexor and extensor muscles of the forearm stabilizing force magnitude in finger pressing tasks. Here, we directly test for the presence and behavior of MU-modes in the tibialis anterior, a non-compartmentalized muscle. Ten participants performed an isometric cyclical dorsiflexion force production task at 1 Hz between 20 and 40% of maximal voluntary contraction and electromyographic (EMG) data were collected from two high-density wireless sensors placed on the skin over the right tibialis anterior. EMG data were decomposed into individual motor unit frequencies and resolved into sets of MU-modes. Inter-cycle analysis of MU-mode magnitudes within the framework of the uncontrolled manifold (UCM) hypothesis was used to quantify force-stabilizing synergies. Two or three MU-modes were identified in all participants and trials accounting, on average, for 69% of variance and were robust to cross-validation measurements. Strong dorsiflexion force-stabilizing synergies in the space of MU-modes were present in all participants and for both electrode locations as reflected in variance within the UCM (median 954, IQR 511-1924) exceeding variance orthogonal to the UCM (median 5.82, IQR 2.9-17.4) by two orders of magnitude. In contrast, MU-mode-stabilizing synergies in the space of motor unit frequencies were not present. This study offers strong evidence for the existence of synergic control mechanisms at the level of motor units independent of muscle compartmentalization, likely organized within spinal cord circuitry.

Intramuscle Synergies: Their Place in the Neural Control Hierarchy.

We accept a definition of synergy introduced by Nikolai Bernstein and develop it for various actions, from those involving the whole body to those involving a single muscle. Furthermore, we use two major theoretical developments in the field of motor control-the idea of hierarchical control with spatial referent coordinates and the uncontrolled manifold hypothesis-to discuss recent studies of synergies within spaces of individual motor units (MUs) recorded within a single muscle. During the accurate finger force production tasks, MUs within hand extrinsic muscles form robust groups, with parallel scaling of the firing frequencies. The loading factors at individual MUs within each of the two main groups link them to the reciprocal and coactivation commands. Furthermore, groups are recruited in a task-specific way with gains that covary to stabilize muscle force. Such force-stabilizing synergies are seen in MUs recorded in the agonist and antagonist muscles but not in the spaces of MUs combined over the two muscles. These observations reflect inherent trade-offs between synergies at different levels of a control hierarchy. MU-based synergies do not show effects of hand dominance, whereas such effects are seen in multifinger synergies. Involuntary, reflex-based, force changes are stabilized by intramuscle synergies but not by multifinger synergies. These observations suggest that multifinger (multimuscle synergies) are based primarily on supraspinal circuitry, whereas intramuscle synergies reflect spinal circuitry. Studies of intra- and multimuscle synergies promise a powerful tool for exploring changes in spinal and supraspinal circuitry across patient populations.

Intra-muscle Synergies Stabilizing Reflex-mediated Force Changes.

We used the framework of the uncontrolled manifold hypothesis to explore force-stabilizing synergies and motor equivalence in the spaces of individual motor unit (MU) firing frequencies. Healthy subjects performed steady force production tasks by pressing with one finger or three fingers of a hand. Surface EMG was used to identify individual MU action potentials. MUs formed stable groups (MU-modes) with parallel scaling of the firing frequency in both flexor digitorum superficialis (FDS) and extensor digitorum communis (EDC) that allowed identifying them with the reciprocal and coactivation commands. Smooth lifting of the fingers by an "inverse piano" device led to an unintentional, reflex-based force increase. There was significantly larger motion in the space of MU-modes that kept the force unchanged (motor equivalent) compared to motion that changed force (non-motor equivalent). The force change was stabilized by co-varying contributions of the MU-modes defined separately for FDS and EDC. In contrast, analysis of the three-finger task in the space of individual finger forces showed no synergies stabilizing total force change. Effects of hand dominance were seen on multi-finger synergies but not intra-muscle synergies. We conclude that spinal mechanisms, such as recurrent inhibition and reflex loops from proprioceptors, contribute significantly to intra-muscle synergies, while multi-finger synergies reflect supra-spinal processes. These results provide methods to explore the contributions of spinal vs supraspinal circuitry to changed motor synergies in populations with a variety of neurological disorders.

Clopidogrel versus ticagrelor for antiplatelet therapy in transcarotid artery revascularization in the Society for Vascular Surgery Vascular Quality Initiative.

OBJECTIVE: Transcarotid artery revascularization (TCAR) with dynamic flow reversal is a hybrid technique for operative management of carotid artery stenosis. Dual antiplatelet therapy is recommended for patients undergoing TCAR; however, nonresponders to these medications may be predisposed to perioperative thromboembolic complications. Prevalent in up to 44% to 66% of patients taking clopidogrel, high on-treatment platelet reactivity may thus be responsible for a portion of adverse cerebrovascular events in TCAR. A previous single-institution study has demonstrated the use of ticagrelor as a viable alternative to clopidogrel for antiplatelet therapy in patients undergoing TCAR; however, large-scale comparisons between clopidogrel and ticagrelor are needed to confirm the safety of ticagrelor outside of highly selected patients and providers. METHODS: Data from patients enrolled in the Society for Vascular Surgery Vascular Quality Initiative undergoing TCAR with a perioperative antiplatelet therapy regimen including either clopidogrel or ticagrelor from January 2015 to March 2021 were analyzed and compared. Multivariable logistic regression and propensity score matching were used to evaluate the primary 30-day outcomes of stroke, major bleeding event, and combined stroke/myocardial infarction (MI)/death rate while adjusting for baseline characteristics of the patients. RESULTS: A total of 11,973 patients underwent TCAR with a dual antiplatelet therapy regimen that included clopidogrel vs 426 patients with ticagrelor. Compared with patients on clopidogrel, patients on ticagrelor were significantly more likely to have coronary artery disease (51% vs 66%; P < .001), particularly unstable angina or MI within 6 months (3% vs 9%; P < .001), and more likely to have insulin-dependent diabetes mellitus (14% vs 19%; P < .001). The unadjusted 30-day rates of stroke, major bleeding, and combined stroke/MI/death were not statistically significant among both groups (1.3% vs 0.5%; P = .14, 2.4% vs 1.4%; P = .18, and 1.9% vs 1.6%; P = .71], respectively). After multivariable adjustment and propensity matching, these remained statistically insignificant. CONCLUSIONS: Despite a substantially higher medical risk in patients undergoing TCAR with ticagrelor, 30-day rates of stroke, major bleeding events, and combined stroke/MI/death were similar between patients on ticagrelor and clopidogrel as part of adjunctive antiplatelet therapy. Randomized prospective trials, and studies with larger sample sizes and longer follow-up will be needed to better examine the outcome differences in TCAR between these two medications.

Stability of Action and Kinesthetic Perception in Parkinson's Disease.

We present a review of action and perception stability within the theoretical framework based on the idea of control with spatial referent coordinates for the effectors at a number of hierarchical levels. Stability of salient variables is ensured by synergies, neurophysiological structures that act in multi-dimensional spaces of elemental variables and limit variance to the uncontrolled manifold during action and iso-perceptual manifold during perception. Patients with Parkinson's disease show impaired synergic control reflected in poor stability (low synergy indices) and poor agility (low indices of anticipatory synergy adjustments prior to planned quick actions). They also show impaired perception across modalities, including kinesthetic perception. We suggest that poor stability at the level of referent coordinates can be the dominant factor leading to poor stability of percepts.

Perturbation-induced fast drifts in finger enslaving.

We explored changes in finger forces and in an index of unintentional finger force production (enslaving) under a variety of visual feedback conditions and positional finger perturbations. In particular, we tested a hypothesis that enslaving would show a consistent increase with time at characteristic times of about 1-2 s. Young healthy subjects performed accurate force production tasks under visual feedback on the total force of the instructed fingers (index and ring) or enslaved fingers (middle and little). Finger feedback was covertly alternated between master and enslaved fingers in a random fashion. The feedback could be presented over the first 5 s of the trial only or over the whole trial duration (21 s). After 5 s, the fingers were lifted by 1 cm, and after 15 s, the fingers were lowered to the initial position. The force of the instructed fingers drifted toward lower magnitudes in all conditions except the one with continuous feedback on that force. The force of enslaved fingers showed variable behavior across conditions. In all conditions, the index of enslaving showed a consistent increase with the time constant varying between 1 and 3 s. We interpret the results as pointing at the spread of excitation to enslaved fingers (possibly, in the cortical M1 areas). The relatively fast changes in enslaving under positional finger perturbations suggest that quick changes of the input into M1 from pre-M1 areas can accelerate the hypothesized spread of cortical excitation.

Outcomes and strategy of tailored antiplatelet therapy with ticagrelor in patients undergoing transcarotid artery revascularization.

OBJECTIVE: Antiplatelet drug resistance is associated with periprocedural ischemic complications in patients undergoing intravascular stent implantation. Nonresponders are subject to increased risk of stent thrombosis and in-stent stenosis, and high on-treatment platelet reactivity (HTPR) is present in up to 44% of patients taking clopidogrel, a widely used component of dual antiplatelet therapy (DAPT). Evidence points to ticagrelor as a viable alternative to overcome HTPR on clopidogrel. Studies have shown fewer thromboembolic events with ticagrelor therapy; however, results on bleeding risk are mixed, and its safety and efficacy in hybrid operative techniques have yet to be established. Transcarotid artery revascularization (TCAR) is a hybrid procedure to treat severe carotid stenosis. The objective of this study was to establish the safety and efficacy of ticagrelor as part of DAPT in patients undergoing TCAR and to develop a protocol to ensure adequate antithrombotic protection throughout the operative course. METHODS: Data were collected retrospectively for patients undergoing TCAR on DAPT of aspirin and ticagrelor for symptomatic (≥50%) or asymptomatic (≥80%) carotid stenosis. Preoperative platelet reactivity was determined using Thromboelastography with Platelet Mapping (Haemonetics Corporation, Braintree, Mass), with adequate platelet reactivity defined as maximal amplitude produced by adenosine diphosphate <50 mm. The primary safety end point was 30-day major bleeding event rate. Primary efficacy end points were 30-day incidence of ipsilateral cerebrovascular ischemic event (stroke or transient ischemic attack), myocardial infarction, and death. Secondary end points were postoperative length of hospital stay, procedure time, and clamp/flow reversal time. RESULTS: Sixty-seven TCAR procedures with patients receiving periprocedural DAPT of ticagrelor and aspirin were performed during the study period. Patients had an average age of 79 years, and 28 (42%) were symptomatic. The mean procedure time was 45.8 ± 9.2 minutes, with a mean clamp/flow reversal time of 4.8 ± 1.5 minutes, and mean postoperative length of hospital stay of 3.1 ± 2.2 days for inpatients and 1.3 ± 0.8 days for outpatients. Technical success was achieved in all cases, with no 30-day major bleeding events and no occurrence of ipsilateral cerebrovascular ischemic event, myocardial infarction, or death. CONCLUSIONS: Initial experience with ticagrelor as part of DAPT in patients undergoing TCAR demonstrated its safety and efficacy in both symptomatic and asymptomatic disease. No bleeding events or thromboembolic complications occurred. Furthermore, a protocol to administer ticagrelor to assay for HTPR on ticagrelor and consequent medication and patient management is proposed. Ticagrelor may represent a safe and effective alternative to overcome clopidogrel nonresponsiveness in DAPT regimens for TCAR.

Outcomes of Transcarotid Artery Revascularization (TCAR) in Octogenarians and Older.

BACKGROUND: Carotid revascularization, both endarterectomy (CEA) and transfemoral carotid artery stenting (TFCAS), are associated with an increased risk of adverse outcomes in patients aged ≥80 years. Transcarotid artery revascularization (TCAR) is a technique that combines surgical principles of neuroprotection with less invasive endovascular techniques to treat severe carotid stenosis. Data from a recent registry study comparing TCAR with that of CEA and TFCAS demonstrated no significant difference in outcomes between TCAR and CEA in patients aged ≥80 years, and a significant reduction in stroke and composite outcomes between TCAR and TFCAS in patients aged ≥80 years. To add to these studies, a more in-depth analysis of demographic, procedural, and outcome factors is warranted for elderly patients aged ≥80 years undergoing TCAR. At our center, with a large volume of elderly patients based on local demographics, we expect there will be no significant effect of age on outcome measures between patients aged <80 years and those aged ≥80 years. METHODS: Data were collected retrospectively for patients undergoing TCAR for symptomatic (≥50%) or asymptomatic (≥80%) extracranial carotid artery stenosis. Primary endpoints were the incidence of ipsilateral cerebrovascular ischemic event (stroke or transient ischemic attack), myocardial infarction (MI), cranial nerve injury, and death through 30 days after the procedure. Secondary endpoints were postoperative length of hospital stay (LOS), procedure time, carotid artery clamp/flow reversal time, and fluoroscopy time. Subgroup analyses were performed to examine the effect of inpatient/outpatient status, carotid symptomatology, and type of anesthesia on secondary outcomes. RESULTS: Ninety-seven TCAR procedures were performed at our institution during the study period, of which 43 (44%) were on patients aged ≥80 years. Technical success was achieved in all cases, with no incidence of cerebrovascular ischemic event, MI, cranial nerve injury, or mortality through 30 days after procedure. In patients aged ≥80 years, the mean procedure time was 47 ± 12 min, clamp/flow reversal time was 4.7 ± 1.1 min, fluoroscopy time was 4.1 ± 1.6 min, and median LOS was 2.0 ± 1.0 days. Procedure time, clamp/flow reversal time, and fluoroscopy time were not significantly different between the age groups. However, there was a significant difference in the LOS, with patients aged <80 years demonstrating a median LOS of 1.0 ± 0.0 days (P = <0.001). CONCLUSIONS: Our experience with TCAR confirms that it can be performed successfully in both symptomatic and asymptomatic high-risk elderly patients, with our series finding no incidence of perioperative cerebral ischemic event, MI, or death.

Lower extremity revascularization via endovascular and surgical approaches: A systematic review with emphasis on combined inflow and outflow revascularization.

This review is intended to help clinicians and patients understand the present state of peripheral artery disease, appreciate the progression and presentation of critical limb ischemia/chronic limb-threatening ischemia, and make informed decisions regarding inflow and outflow endovascular revascularization and surgical treatment options within the context of current debates in the medical community. A controlled literature search was performed to obtain research on outcomes of critical limb ischemia patients undergoing complete leg revascularization for peripheral artery disease inflow and outflow disease. Data for this review were identified by queries of medical and life science databases, expert referral, and references from relevant papers published between 1997 and 2019, resulting in 48 articles. The literature review herein indicates that endovascular revascularization-including ballooning, stenting, and atherectomy-is an effective peripheral artery disease therapy for both above the knee and below the knee disease, and can safely and effectively treat both inflow and outflow disease. As such, it plays a leading role in the therapy of lower extremity artery disease.

What do people match when they try to match force? Analysis at the level of hypothetical control variables.

We used the theory of control with spatial referent coordinates (RC) to explore how young, healthy persons modify finger pressing force and match forces between the two hands. Three specific hypotheses were tested related to patterns of RC and apparent stiffness (defined as the slope of force-coordinate relation) used in the presence of visual feedback on the force and in its absence. The subjects used the right hand to produce accurate force under visual feedback; further the force could be increased or decreased, intentionally or unintentionally (induced by controlled lifting or lowering of the fingertips). The left hand was used to match force without visual feedback before and after the force change; the match hand consistently underestimated the actual force change in the task hand. The "inverse piano" device was used to compute RC and apparent stiffness. We found very high coefficients of determination for the inter-trial hyperbolic regressions between RC and apparent stiffness in the presence of visual feedback; the coefficients of determination dropped significantly without visual feedback. There were consistent preferred sharing patterns in the space of RC and apparent stiffness between the task and match hands across subjects. In contrast, there was much less consistency between the task and match hands in the magnitudes of RC and apparent stiffness observed in individual trials. Compared to the task hand, the match hand showed consistently lower magnitudes of apparent stiffness and, correspondingly, larger absolute magnitudes of RC. Involuntary force changes produced by lifting and lowering the force sensors led to significantly lower force changes compared to what could be expected based on the computed values of apparent stiffness and sensor movement amplitude. The results confirm the importance of visual feedback for stabilization of force in the space of hypothetical control variables. They suggest the existence of personal traits reflected in preferred ranges of RC and apparent stiffness across the two hands. They also show that subjects react to external perturbations, even when instructed "not to interfere": Such perturbations cause unintentional and unperceived drifts in both RC and apparent stiffness.

Intravascular Ultrasound Validation of Contemporary Angiographic Scores Evaluating the Severity of Calcification in Peripheral Arteries.

PURPOSE: To validate 3 angiographic scoring systems for peripheral artery calcification using intravascular ultrasound (IVUS) as the gold standard. METHODS: The study employed preprocedure angiography and IVUS data from 47 patients (median age 72 years; 34 men) in the 55-patient JetStream G3 Calcium Study ( ClinicalTrials.gov identifier NCT01273623) to validate the 3 angiographic scoring systems [Peripheral Academic Research Consortium (PARC), Peripheral Arterial Calcium Scoring System (PACSS), and the DEFINITIVE Ca++ trial]. Preprocedure angiograms were analyzed using conventional quantitative vessel analysis software in 2 orthogonal views. Calcium length was evaluated by markers placed beside the artery during the procedure; calcium deposit(s) were assessed as being on one or both sides of the vessel wall. The 3 calcium scoring systems used these 2 basic angiographic elements to evaluate calcium severity. Based on these criteria, calcium severity varied from none to focal, mild, moderate, or severe in PARC; grade 0 to 4 in PACSS; and none, moderate, or severe in the DEFINITIVE Ca++ system. Calcium location on IVUS was classified as superficial, deep, or mixed. Lesion length was the segment between the most normal looking proximal and distal reference sites. Superficial, deep, and calcium length were based on motorized IVUS pullback. RESULTS: IVUS detected calcium in 44/47 (93.6%) lesions, and angiography detected calcium in 26/47 (55.3%) lesions (p<0.001). The sensitivity, specificity, positive predictive value, and negative predictive value of angiography relative to IVUS were 59%, 100%, 100%, and 14%, respectively. With increasing severity of angiographic calcium, there was a stepwise increase in the prevalence of IVUS superficial calcium and the maximum arc and length of superficial calcium. Using PARC criteria, with increasing severity of calcification, IVUS maximum calcium arc increased from 120° for none to 305° for severe (p<0.001); the length of calcium increased from 7 to 68 mm (p<0.001). Though a similar trend was seen in IVUS superficial calcium, it was not observed in IVUS deep calcium. Similar observations were seen when using the PACSS and DEFINITIVE Ca++ scoring systems. CONCLUSION: IVUS confirmed that the PARC, PACSS, and DEFINITIVE Ca++ calcium scoring systems can be used to classify the degree of calcium in peripheral artery disease, especially superficial calcium.

Outcomes of endovascular aneurysm repair with contemporary volume-dependent sac embolization in patients at risk for type II endoleak.

OBJECTIVE: The aim of this study was to evaluate outcomes of intraoperative aneurysm sac embolization during endovascular aneurysm repair (EVAR) in patients considered at risk for type II endoleak (EII), using a sac volume-dependent dose of fibrin glue and coils. METHODS: Between January 2012 and December 2014, 126 patients underwent EVAR. Based on preoperative computed tomography evaluation of anatomic criteria, 107 patients (85%) were defined as at risk for EII and assigned to randomization for standard EVAR (group A; n = 55, 44%) or EVAR with intraoperative sac embolization (group B; n = 52, 42%); the remaining 19 patients (15%) were defined as at low risk for EII and excluded from the randomization (group C). Computed tomography scans were evaluated with OsiriX Pro 4.0 software to obtain aneurysm sac volume. Freedom from EII, freedom from EII-related reintervention, and aneurysm sac volume shrinkage at 6, 12, and 24 months were compared by Kaplan-Meier estimates. Patients in group C underwent the same follow-up protocol as groups A and B. RESULTS: Patient characteristics, Society for Vascular Surgery comorbidity scores (0.99 ± 0.50 vs 0.95 ± 0.55; P = .70), and operative time (149 ± 50 minutes vs 157 ± 39 minutes; P = .63) were similar for groups A and B. Freedom from EII was significantly lower for group A compared with group B at 3 months (58% vs 80%; P = .002), 6 months (68% vs 85%; P = .04), and 12 months (70% vs 87%; P = .04) but not statistically significant at 24 months (85% vs 87%; P = .57). Freedom from EII-related reintervention at 24 months was significantly lower for group A compared with group B (82% vs 96%; P = .04). Patients in group B showed a significantly overall mean difference in aneurysm sac volume shrinkage compared with group A at 6 months (-11 ± 17 cm(3) vs -2 ± 14 cm(3); P < .01), 12 months (-18 ± 26 cm(3) vs -3 ± 32 cm(3); P = .02), and 24 months (-27 ± 25 cm(3) vs -5 ± 26 cm(3); P < .01). Patients in group C had the lowest EII rate compared with groups A and B (6 months, 5%; 12 months, 6%; 24 months, 0%) and no EII-related reintervention. CONCLUSIONS: This randomized study confirms that sac embolization during EVAR, using a sac volume-dependent dose of fibrin glue and coils, is a valid method to significantly reduce EII and its complications during early and midterm follow-up in patients considered at risk. Although further confirmatory studies are needed, the faster aneurysm sac volume shrinkage over time in patients who underwent embolization compared with standard EVAR may be a positive aspect influencing the lower EII rate also during long-term follow-up.

Contemporary results of carotid endarterectomy in "normal-risk" patients from the Society for Vascular Surgery Vascular Registry.

OBJECTIVE: Acceptable complication rates after carotid endarterectomy (CEA) are drawn from decades-old data. The recent Carotid Revascularization Endarterectomy versus Stenting Trial (CREST) demonstrated improved stroke and mortality outcomes after CEA compared with carotid artery stenting, with 30-day periprocedural CEA stroke rates of 3.2% and 1.4% for symptomatic (SX) and asymptomatic (ASX) patients, respectively. It is unclear whether these target rates can be attained in "normal-risk" (NR) patients experienced outside of the trial. This study was done to determine the contemporary results of CEA from a broader selection of NR patients. METHODS: The Society for Vascular Surgery (SVS) Vascular Registry was examined to determine in-hospital and 30-day event rates for NR, SX, and ASX patients undergoing CEA. NR was defined as patients without anatomic or physiologic risk factors as defined by SVS Carotid Practice Guidelines. Raw data and risk-adjusted rates of death, stroke, and myocardial infarction (MI) were compared between the ASX and SX cohorts. RESULTS: There were 3977 patients (1456 SX, 2521 ASX) available for comparison. The SX group consisted of more men (61.7% vs 57.0%; P = .0045) but reflected a lower proportion of white patients (91.3% vs 94.4%; P = .0002), with lower prevalence of coronary artery disease (P < .0001), prior MI (P < .0001), peripheral vascular disease (P = .0017), and hypertension (P = .029), although New York Heart Association grade >3 congestive heart failure was equally present in both groups (P = .30). Baseline stenosis >80% on duplex imaging was less prevalent among SX patients (54.2% vs 67.8%; P < .0001). Perioperative stroke rates were higher for SX patients in the hospital (2.8% vs 0.8%; P < .0001) and at 30 days (3.4% vs 1.0%; P < .0001), which contributed to the higher composite death, stroke, and MI rates in the hospital (3.6% vs 1.8; P = .0003) and at 30 days (4.5% vs 2.2%; P < .0001) observed in SX patients. After risk adjustment, the rate of stroke/death was greater among SX patients in the hospital (odds ratio, 2.05; 95% confidence interval, 1.18-3.58) although not at 30 days (odds ratio, 1.36; 95% confidence interval, 0.85-2.17). No in-hospital or 30-day differences were observed for death or MI by symptom status. CONCLUSIONS: The SVS Vascular Registry results for CEA in NR patients are similar by symptom status to those reported for CREST and may serve as a benchmark for comparing results of alternative therapies for treatment of carotid stenosis in NR patients outside of monitored clinical trials. The contemporary perioperative risk of stroke after CEA in NR patients continues to be higher for SX than for ASX patients.