Computational fluid dynamic analysis of upper airway procedures in equine larynges.

Introduction: Computational fluid dynamics (CFD) has proven useful in the planning of upper airway surgery in humans, where it is used to anticipate the influence of the surgical procedures on post-operative airflow. This technology has only been reported twice in an equine model, with a limited scope of airflow mechanics situations examined. The reported study sought to widen this application to the variety of procedures used to treat equine recurrent laryngeal neuropathy (RLN). The first objective of this study was to generate a CFD model of an ex-vivo box model of ten different equine larynges replicating RLN and four therapeutic surgeries to compare the calculated impedance between these procedures for each larynx. The second objective was to determine the accuracy between a CFD model and measured airflow characteristics in equine larynges. The last objective was to explore the anatomic distribution of changes in pressure, velocity, and turbulent kinetic energy associated with the disease (RLN) and each surgical procedure performed. Methods: Ten equine cadaveric larynges underwent inhalation airflow testing in an instrumented box while undergoing a concurrent computed tomographic (CT) exam. The pressure upstream and downstream (outlet) were measured simultaneously. CT image segmentation was performed to generate stereolithography files, which underwent CFD analysis using the experimentally measured outlet pressure. The ranked procedural order and calculated laryngeal impedance were compared to the experimentally obtained values. Results and discussion: The CFD model agreed with the measured results in predicting the procedure resulting in the lowest post-operative impedance in 9/10 larynges. Numerically, the CFD calculated laryngeal impedance was approximately 0.7 times that of the measured calculation. Low pressure and high velocity were observed around regions of tissue protrusion within the lumen of the larynx. RLN, the corniculectomy and partial arytenoidectomy surgical procedures exhibited low pressure troughs and high velocity peaks compared to the laryngoplasty and combined laryngoplasty/corniculectomy procedures. CFD modeling of the equine larynx reliably calculated the lowest impedance of the different surgical procedures. Future development of the CFD technique to this application may improve numerical accuracy and is recommended prior to consideration for use in patients.

A biomechanical comparison of a novel two-loop suture technique and two sutures for laryngoplasty in the horse.

OBJECTIVES: Evaluation of the strength of the novel suture technique by comparison with a 2-interrupted suture technique. SAMPLE: 40 equine larynges. PROCEDURES: 40 larynges were used; 16 laryngoplasties were performed using the currently accepted 2-suture technique and 16 using the novel suture technique. These specimens were subjected to a single cycle to failure. Eight specimens were used to compare the rima glottidis area achieved with 2 different techniques. RESULTS: The mean force to failure, as well as the rima glottidis area of both constructs, were not significantly different. The cricoid width did not have a significant effect on the force to failure. CLINICAL RELEVANCE: Our results suggest that both constructs are equally strong and can achieve a similar cross-sectional area of the rima glottidis. Laryngoplasty ("tie-back") is currently the treatment of choice for horses with exercise intolerance due to recurrent laryngeal neuropathy. Failure to maintain the expected degree of arytenoid abduction post-surgery occurs in some horses. We believe this novel 2-loop pulley load-sharing suture technique can help achieve and, more importantly, maintain the desired degree of abduction during surgery.

Computed tomographic geometrical analysis of surgical treatments for equine recurrent laryngeal neuropathy.

OBJECTIVES: To characterize the 3-D geometry of the equine larynx replicating laryngeal hemiplegia and 4 surgical interventions by use of CT under steady-state airflow conditions. Secondly, to use fluid mechanic principles of flow through a constriction to establish the relationship between measured airflow geometries with impedance for each surgical procedure. SAMPLE: 10 cadaveric horse larynges. PROCEDURES: While CT scans were performed, inhalation during exercise conditions was replicated for each of the following 5 conditions: laryngeal hemiplegia, left laryngoplasty with ventriculocordectomy, left laryngoplasty with ipsilateral ventriculocordectomy and arytenoid corniculectomy, corniculectomy, and partial arytenoidectomy for each larynx while CT scans were performed. Laryngeal impedance was calculated, and selected cross-sectional areas were measured along each larynx for each test. Measured areas and constriction characteristics were analyzed with respect to impedance using a multilevel, mixed-effects model. RESULTS: Incident angle, entrance coefficient, outlet coefficient, friction coefficient, orifice thickness, and surgical procedure were significantly associated with upper airway impedance in the bivariable model. The multivariate model showed a significant influence of incident angle, entrance coefficient, and surgical procedure on impedance; however, the orifice thickness became nonsignificant within the model. CLINICAL RELEVANCE: Laryngeal impedance was significantly associated with the entrance configuration for each procedure. This suggested that the equine upper airway, despite having a highly complex geometry, adheres to fluid dynamic principles applying to constrictions within pipe flow. These underlying flow characteristics may explain the clinical outcomes observed in some patients, and lead to areas of improvement in the treatment of obstructive upper airway disease in horses.

Personalized subcutaneous implantable cardioverter-defibrillator sensing vectors generated by mathematical rotation increase device eligibility whilst preserving device performance.

AIMS: Approximately 5.7% of potential subcutaneous implantable cardioverter-defibrillator (S-ICD) recipients are ineligible by virtue of their vector morphology, with higher rates of ineligibility observed in some at-risk groups. Mathematical vector rotation is a novel technique that can generate a personalized sensing vector, one with maximal R:T ratio, using electrocardiogram (ECG) signal recorded from the present S-ICD location. METHODS AND RESULTS: A cohort of S-ICD ineligible patients were identified through ECG screening of ICD patients with no ventricular pacing requirement and their personalized vectors were generated using ECG signal from a Holter monitor. Subcutaneous ICD eligibility in this cohort was then recalculated. In a separate cohort, episodes of arrhythmia were recorded in patients undergoing arrhythmia induction, and arrhythmia detection in standard S-ICD vectors was compared to rotated vectors using an S-ICD simulator. Ninety-two participants (mean age 64.9 ± 2.7 years) underwent screening and 5.4% were found to be S-ICD ineligible. Personalized vector generation increased the R:T ratio in these vectors from 2.21 to 7.21 (4.54-9.88, P < 0.001) increasing the cohort eligibility from 94.6% to 100%. Rotated S-ICD vectors also showed high ventricular fibrillation (VF) detection sensitivity (97.8%), low time to VF detection (6.1 s), and excellent tachycardia discrimination (sensitivity 96%, specificity 88%), with no significant differences between rotated and standard vectors. CONCLUSION: In S-ICD ineligible patients, mathematical vector rotation can generate a personalized vector that is associated with a significant increase in R:T ratio, resulting in universal device eligibility in our cohort. Ventricular fibrillation detection efficacy, time to VF detection, and tachycardia discrimination were not affected by vector rotation.

Crystal structures of phosphine-supported (η5-cyclo-penta-dien-yl)molybdenum(II) propionyl complexes.

Three cyclo-penta-dienylmolybdenum(II) propionyl complexes featuring tri-aryl-phosphine ligands with different para substituents, namely, dicarbon-yl(η5-cyclo-penta-dien-yl)propion-yl(tri-phenyl-phosphane-κP)molybdenum(II), [Mo(C5H5)(C3H5O)(C18H15P)(CO)2], (1), dicarbon-yl(η5-cyclo-penta-dien-yl)propion-yl[tris-(4-fluoro-phen-yl)phosphane-κP]molybdenum(II), [Mo(C5H5)(C3H5O)(C18H12F3P)(CO)2], (2), and dicarbon-yl(η5-cyclo-penta-dien-yl)propion-yl[tris-(4-meth-oxy-phen-yl)phosphane-κP]molybdenum(II) dichloromethane solvate, [Mo(C5H5)(C3H5O)(C21H21O3P)(CO)2]·CH2Cl2, (3), have been prepared from the corresponding ethyl complexes via phosphine-induced migratory insertion. These complexes exhibit four-legged piano-stool geom-etries with mol-ecular structures quite similar to each other and to related acetyl complexes. The extended structures of the three complexes differ somewhat, with the para substituent of the tri-aryl-phosphine of (2) (fluoro) or (3) (meth-oxy) engaging in non-classical C-H⋯F or C-H⋯O hydrogen-bonding inter-actions. The structure of (3) exhibits modest disorder in the position of one Cl atom of the di-chloro-methane solvent, which was modeled with two sites showing approximately equivalent occupancies [0.532 (15) and 0.478 (15)].

Pain during cardiac implantable electronic device implantation.

In order to evaluate the extent and causes of pain during cardiac implantable electronic device (CIED) implantation in our hospital, a prospective audit over a 23-month period using a patient selfreporting questionnaire was undertaken. In total, 599 procedures were reported, 52.9% for de novo pacemaker implantation and 23.4% for high-energy devices (cardiac resynchronisation therapy defibrillator [CRT-D], implantable cardiac defibrillator [ICD], subcutaneous ICD). Overall, the median pain score was 2/10 (interquartile range 2-4). In total, 61.6% (367/599) reported no pain or mild pain (pain scores 0-3/10), 27.7% (165/599) reported moderate pain (pain score of 4-6/10) and 10.7% (64/599) reported severe pain (pain score of 7-10/10) during the procedure. Significant preimplant worry (odds ratio [OR] 2.13, 95% confidence interval [CI] 1.22 to 3.73) and higher lidocaine doses (OR 1.06, 95%CI 1.00 to 1.11) were associated with severe patient-reported pain. In conclusion, most patients underwent CIED implantation with minimum stress and maximum comfort. An important minority reported severe pain during the procedure. Optimising surgical technique and interventions targeted at reducing pre- and peri-implant worry, particularly in women, and especially in those receiving ICDs, warrants further investigation to reduce patient-reported pain during CIED implantation.

Chitosan-based agent use for hemostasis after cryptorchidectomy in a horse.

OBJECTIVE: To document marked hemorrhage as a complication of inguinal cryptorchidectomy and its successful treatment with a novel chitosan-based hemostatic agent. STUDY DESIGN: Case report. ANIMALS: One healthy 5-year old quarter horse cryptorchid. METHODS: The horse was presented for routine unilateral cryptorchidectomy after prior hemicastration. An inguinal approach was made to the abdomen, and the right external pudendal artery was lacerated at the level of the internal inguinal ring, requiring multiple anesthetic events over a 2-week period in attempts to control hemorrhage. A chitosan-based hemostatic agent was packed into the wound to gain control. RESULTS: Chitosan granules placed in the wound successfully controlled the hemorrhage, whereas the use of gauze packing alone failed. There were no immediate or long-term complications to the chitosan granules; the horse was doing well 18 months postoperatively, and the client was satisfied with the outcome. CONCLUSION: Major hemorrhage was demonstrated from the external pudendal artery and caused difficulties because it occurred deep within the inguinal canal during an inguinal cryptorchidectomy. A chitosan-based hemostatic agent was successfully used to achieve hemostasis. CLINICAL SIGNIFICANCE: The external pudendal artery should be avoided in the medial commissure of the inguinal canal. The use of chitosan-based hemostatic agents warrants further investigation in horses because these products may be useful for controlling major hemorrhage from various causes in equine practice.

Ex vivo evaluation of arytenoid corniculectomy, compared with three other airway interventions, performed on cadaveric equine larynges with simulated recurrent laryngeal neuropathy.

OBJECTIVE: To compare laryngeal impedance, in terms of air flow and pressure, following arytenoid corniculectomy (COR) versus 3 other airway interventions (left-sided laryngoplasty with ipsilateral ventriculocordectomy [LLP], LLP combined with COR [LLPCOR], and partial arytenoidectomy [PA]) performed on cadaveric equine larynges with simulated left recurrent laryngeal neuropathy (RLN) and to determine whether relative laryngeal collapse correlated with the interventions performed. SAMPLE: 28 cadaveric equine larynges. PROCEDURES: Each larynx in states of simulated left RLN alone and with airway interventions in the order LLP, LLPCOR, COR, and PA was evaluated in a box model construct that replicated upper airway flow mechanics consistent with peak exercise in horses. Results for impedance, calculated from airflow and pressure changes, were compared between states for each larynx. Multivariable mixed-effects analysis controlling for repeated measures within larynx was performed to calculate the predicted mean impedance for each state. RESULTS: Results indicated that tracheal adapter diameter, individual larynx properties, airway intervention, and relative laryngeal collapse affected laryngeal impedance. The LLP and LLPCOR interventions had the lowest impedance, whereas the COR and PA interventions did not differ substantially from the simulated left RLN state. Residual intraclass correlation of the model was 27.6 %. CONCLUSIONS AND CLINICAL RELEVANCE: Although impedance was higher for the simulated left RLN with the COR intervention state than with the LLP intervention state, given the clinical success of PA for treating RLN in horses and the similar results for the COR and PA intervention states in the present study, the use of COR warrants further investigation. The residual interclass correlation suggested that individual laryngeal variation affected impedance and may have a clinical effect.

Sacrococcygeal luxation and complete tail amputation following a tail pull injury in a horse.

A 17-year-old Quarter horse mare was presented because of traumatic luxation of the fifth sacral and first coccygeal vertebrae resulting in loss of sensation, motor function, and perfusion of the tail. The case was complicated by an associated tail head hematoma. Due to the severity of the injury, tail amputation was performed at the level of the luxation. Tail amputations in horses at the sacrococcygeal junction following a suspected tail pull injury are infrequently reported in the literature.

Luxation sacrococcygienne et amputation complète de la queue à la suite d'une blessure par traction de la queue chez un cheval. Une jument Quarter horse âgée de 17 ans fut présentée pour cause de luxation traumatique de la cinquième vertèbre sacrée et de la première vertèbre coccygienne résultant en une perte de sensation, de fonction moteur, et de perfusion de la queue. Le cas était compliqué par l'association d'un hématome de la tête de la queue. Compte tenu de la sévérité de la blessure, l'amputation de la queue fut effectuée au site de la luxation. Les amputations de la queue chez les chevaux à la jonction sacrococcygienne à la suite d'une blessure suspectée causée par traction de la queue ne sont rapportées que peu fréquemment dans la littérature.(Traduit par Dr Serge Messier).

Novel technique for prevention of rotation of the distal phalanx relative to the hoof wall in horses with acute laminitis.

OBJECTIVE: To determine the holding capacity of a 5.5-mm-diameter cortical bone screw when placed in the third phalanx (P3) of horses and assess whether screw placement through the dorsal hoof wall into P3 would be tolerated by clinically normal horses and would alleviate signs of pain and prevent P3 rotation in horses with oligofructose-induced laminitis. ANIMALS: 40 limbs from 10 equine cadavers and 19 clinically normal adult horses. PROCEDURES: In part 1 of a 3-part study, a 5.5-mm-diameter cortical bone screw was inserted by use of a lag-screw technique through the dorsal hoof wall midline into P3 of 40 cadaveric limbs and tested to failure to determine screw pullout force. In part 2, 6 horses had 5.5-mm-diameter cortical bone screws placed in both forefeet as described for part 1. Screws were removed 4 days after placement. Horses were monitored for lameness before and for 2 weeks after screw removal. In part 3, 13 horses were randomly assigned to serve as controls (n = 3) or undergo screw placement without (group 2; 6) or with (group 3; 4) a washer. Following the acquisition of baseline data, horses were sedated and administered oligofructose (10 g/kg) via a stomach tube. Twenty-four hours later, screws were placed as previously described in both forefeet of horses in groups 2 and 3. Horses were assessed every 4 hours, and radiographic images of the feet were obtained at 96 and 120 hours after oligofructose administration. Horses were euthanized, and the feet were harvested for histologic examination. RESULTS: The mean ± SD screw pullout force was 3,908.7 ± 1,473.4 N, and it was positively affected by the depth of screw insertion into P3. Horses of part 2 tolerated screw placement and removal well and did not become lame. All horses of part 3 developed signs of acute lameness, and the distance between P3 and the dorsal hoof wall increased slightly over time. The change in the ratio of the dorsal hoof wall width at the extensor process of P3 to that at the tip of P3 over time was the only variable significantly associated with treatment. CONCLUSIONS AND CLINICAL RELEVANCE: Placement of a 5.5-mm-diameter cortical bone screw through the dorsal hoof wall into P3 had sufficient holding power to counteract the pull of the deep digital flexor tendon in approximately 500-kg horses, and placement of such a screw was well tolerated by clinically normal horses but did not alleviate signs of pain in horses with oligofructose-induced laminitis. Further research is necessary before this technique can be recommended for horses with naturally occurring acute laminitis.

Electrode positions, transformation coordinates for ECG reconstruction from S-ICD vectors.

The article contains data pertaining to the reconstruction of an 8-lead ECG from 2 subcutaneous implantable cardioverter defibrillator vectors. The location of electrodes on the precordium required for the data collection are detailed; the flow chart for patient selection and exclusion is shown; the summary data of the root mean square error (RMSE) (in microvolts) and Pearson r for the ECG transformation all cases and the pearson correlation for all the leads measured and reconstructed leads are also shown. Detailed background, methodology and discussion can be found in the linked research article.

Reconstruction of an 8-lead surface ECG from two subcutaneous ICD vectors.

INTRODUCTION: Techniques exist which allow surface ECGs to be reconstructed from reduced lead sets. We aimed to reconstruct an 8-lead ECG from two independent S-ICD sensing electrodes vectors as proof of this principle. METHODS: Participants with ICDs (N=61) underwent 3minute ECGs using a TMSi Porti7 multi-channel signal recorder (TMS international, The Netherlands) with electrodes in the standard S-ICD and 12-lead positions. Participants were randomised to either a training (N=31) or validation (N=30) group. The transformation used was a linear combination of the 2 independent S-ICD vectors to each of the 8 independent leads of the 12-lead ECG, with coefficients selected that minimized the root mean square error (RMSE) between recorded and derived ECGs when applied to the training group. The transformation was then applied to the validation group and agreement between the recorded and derived lead pairs was measured by Pearson correlation coefficient (r) and normalised RMSE (NRMSE). RESULTS: In total, 27 patients with complete data sets were included in the validation set consisting of 57,888 data points from 216 full lead sets. The distribution of the r and NRMSE were skewed. Mean r=0.770 (SE 0.024), median r=0.925. NRMSE mean=0.233 (SE 0.015) median=0.171. CONCLUSIONS: We have demonstrated that the reconstruction of an 8-lead ECG from two S-ICD vectors is possible. If perfected, the ability to generate accurate multi-lead surface ECG data from an S-ICD would potentially allow recording and review of clinical arrhythmias at follow-up.

Increasing age does not affect time to appropriate therapy in primary prevention ICD/CRT-D: a competing risks analysis.

Aims: To evaluate the impact of age on the clinical outcomes in a primary prevention implantable cardioverter defibrillator (ICD)/cardiac resynchronization therapy defibrillator (CRT-D) population. Methods and Results: A retrospective, multicentre analysis of patients aged 60 years and over with primary prevention ICD/CRT-D devices implanted between 1 January 2006 and 1 November 2014 was performed. Survival to follow-up with no therapy (T1), death prior to follow-up with no therapy (T2), delivery of appropriate therapy with survival to follow-up (T3), and delivery of appropriate therapy with death prior to follow-up (T4) were measured. In total, 424 patients were eligible for inclusion in the analysis, mean follow-up of 32.6 months during which time 44 patients (10.1%) received appropriate therapy. The sub-hazard ratio (SHR) for the cumulative incidence of appropriate therapy (T3) according to age at implant was 1.00 (P = 0.851; 95% CI 0.96­1.04). The SHR for cumulative incidence of death (T2) according to age at implant was 1.06 (P < 0.001; 95% CI 1.03­1.01). Age at implant, ischaemic aetiology, baseline haemoglobin, and the presence of diabetes mellitus were predictors of all-cause mortality. Conclusion: Age has no impact on the time to appropriate therapy, but risk of death prior to therapy increases by 6% for every year increment. As the ICD population ages, the proportion who die without receiving appropriate therapy increases due to competing risks. Characterizing competing risks predictive of death independent of ICD indication would focus therapy on those with potential to benefit and reduce unnecessary exposure to ICD-related morbidity.

Quality of Adhesions After Sutured Paramedian vs. Laparoscopic Toggle Abomasopexy in an Ovine Model.

OBJECTIVE: To evaluate adhesions created by abomasopexies using either chromic gut or polydioxanone suture through a right paramedian approach and determine whether a laparoscopic toggle technique is an acceptable alternative to open abomasopexy using an ovine model. STUDY DESIGN: Experimental study. ANIMALS: Mature ewes (n=30). METHODS: Ewes received 1 of 3 abomasopexy techniques (n=10): right paramedian approach using chromic gut or polydioxanone, or a laparoscopic toggle technique. After euthanasia 8 weeks postoperatively, adhesions were removed en bloc and adhesion cross-sectional area (width × length) and depth (distance from abdominal wall to abomasum) were measured and given a grade of 0-3 based on the quality of adhesion. Surgical time was recorded and compared for each technique. Significance was set at P≤.05. RESULTS: Abomasopexies performed with either suture material resulted in a significantly larger mean cross-sectional area and higher adhesion grades compared to those performed using the toggle. Width and length of adhesions formed using chromic gut or polydioxanone were not significantly different; however, both were significantly wider and longer than those formed using the toggle. The laparoscopic toggle technique required significantly less surgical time than the sutured techniques. CONCLUSION: Polydioxanone is as effective as chromic gut suture material in inducing abomasal adhesion formation in our sheep model. The clinical significance of the size and grade of adhesions formed is unknown and requires further investigation before the laparoscopic toggle technique can be recommended as a replacement for paramedian abomasopexy in cattle for the treatment of displaced abomasum.

Left and Right Parasternal Sensing for the S-ICD in Adult Congenital Heart Disease Patients and Normal Controls.

BACKGROUND: This study investigated the impact of a right parasternal sensing electrode position on the R- and T-wave amplitudes and the R:T ratio in three subcutaneous implantable cardioverter defibrillator (S-ICD) vectors in patients with adult congenital heart disease (ACHD) and normal controls. METHODS: Conventional left parasternal sensing electrode position and right parasternal sensing electrode positions were used to collect 10-second electrograms, recorded through an 80-electrode body surface mapping technology (Prime ECG™ system, Heartscape Technologies Inc., now Verathon, Columbia, MD, USA). Recordings were made in the supine, prone, left lateral, right lateral, sitting, and standing positions in using both the standard electrode vector position and the right parasternal positions. RESULTS: Forty patients were recruited and 37 patients were used for analysis. Twenty-seven (73%) had complex ACHD; 10 patients had normal hearts and acted as controls. A total of 3,708 data points were analyzed. There were no significant differences in the R:T ratio when measured in ACHD patients in the right compared to the left parasternal lead position. In contrast, there were important differences in the magnitude of the R:T ratio when measured in control patients in the right compared to the left parasternal lead position; in the primary vector, the R:T ratio was greater in right than left by 2.99 (P = 0.0002; 95% confidence interval [CI]: 1.48-4.50) and in the secondary vector, the R:T ratio was smaller in the right than in the left by 0.77 (P = 0.004; 95% CI: -1.58-0.05). CONCLUSION: In selected patients, a right parasternal lead position may provide a useful alternative sensing configuration for the S-ICD.