Comparison of anterior mitral line and mitral isthmus line for ablation of mitral annular flutter.

BACKGROUND: Mitral annular flutter (MAF) is the most common left atrial macro-reentrant arrhythmia following catheter ablation of atrial fibrillation (AF). The best ablation approach for this arrhythmia remains unclear. METHODS: This single-center, retrospective study sought to compare the acute and long-term outcomes of patients with MAF treated with an anterior mitral line (AML) versus a mitral isthmus line (MIL). Acute ablation success, complication rates, and long-term arrhythmia recurrence were compared between the two groups. RESULTS: Between 2015 and 2021, a total of 81 patients underwent ablation of MAF (58 with an AML and 23 with a MIL). Acute procedural success defined as bidirectional block was achieved in 88% of the AML and 91% of the MIL patients respectively (p = 1.0). One year freedom from atrial arrhythmias was 49.5% versus 77.5% and at 4 years was 24% versus 59.6% for AML versus MIL, respectively (hazard ratio [HR]: 0.38, confidence interval [CI]: 0.17-0.82, p = .009). Fewer patients in the MIL group had recurrent atrial flutter when compared to the AML group (HR: 0.32, CI: 0.12-0.83, p = .009). The incidence of recurrent AF, on the other side, was not different between both groups (21.7% vs. 18.9%; p = .76). There were no serious adverse events in either group. CONCLUSION: In this retrospective study of patients with MAF, a MIL compared to AML was associated with a long-term reduction in recurrent atrial arrhythmias driven by a reduction in macroreentrant atrial flutters.

Feasibility, Efficacy, and Safety of Fluoroless Ablation of VT in Patients With Structural Heart Disease.

BACKGROUND: Catheter ablation of ventricular tachycardia (VT) typically requires radiation exposure with its potential adverse health effects. A completely fluoroless ablation approach is achievable using a combination of electroanatomical mapping and intracardiac echocardiography. Nonetheless, data in patients undergoing VT ablation are limited. OBJECTIVES: This study aimed to determine the feasibility, efficacy, and safety of VT ablation in patients with structural heart disease using a zero-fluoroscopy approach. METHODS: This multicenter study included consecutive patients with ischemic and nonischemic cardiomyopathy undergoing fluoroless VT ablation. Patients requiring epicardial access or coronary angiography were excluded. RESULTS: Between 2017 and 2023 a total of 198 patients (aged 66.4 ± 13.4 years, 76% male, 48% ischemic) were included. Most patients (95.4%) underwent left ventricular (LV) mapping and/or ablation, which was conducted via transseptal route in 54.5% (n = 103), via retrograde aortic route in 43.4% (n = 82), and using a combined approach in 2.1% (n = 4). Two-thirds of patients had a cardiac device, including a biventricular device in 15%; 2 patients had a LV assist device, and 1 patient had a mechanical aortic valve prosthesis. The mean total procedural time was 211 ± 70 minutes, and the total radiofrequency time was 30 ± 22 minutes. During a follow-up period of 22 ± 18 months, the freedom from VT recurrence was 80%, and 7.6% of patients underwent a repeated ablation. Procedural-related complications occurred in 6 patients (3.0%). CONCLUSIONS: Fluoroless ablation of VT in structural heart disease is feasible, effective, and safe when epicardial mapping/ablation is not required.

The USCENTCOM Walking Blood Bank Performance Benchmark and Anticipated Benefit of Universal Low Titer Type O Screening.

The walking blood bank (WBB) is a system for emergency blood acquisition from nearby donors if a patient's blood needs exceed the immediate supply. USCENTCOM medical units will perform a walking blood bank if immediate blood requirements exceed the local supply. A benchmark WBB performance time was needed to provide a training goal for military WBB exercises. An expeditionary WBB performance time benchmark was created from prospective measurements of USCENTCOM medical unit performance times over 9 months. The mean total time, and new performance benchmark, for a WBB in USCENTCOM was 41.4 min +/- 13.2 min. USCENTCOM time from donor arrival to a transfusable unit mean time was 34.4 +/- 12.1 min. Expeditionary medical units conducting a WBB should expect to meet or exceed the provided benchmark.

Military Blood Supply and Distribution in USCENTCOM.

In expeditionary environments, the consistent availability of blood for casualty care is imperative yet challenging. Responding to evidence and the specific needs of its expeditionary context, the US Central Command (USCENTCOM) prioritized supplying stored low titer O whole blood (LTOWB) to its units from March, 2023 onward. A strategy was devised to set minimal LTOWB on-hand supply benchmarks, determined by the number of operating beds and point of injury teams. This transition led to a 54% reduction in orders for packed red blood cells. As a countermove, the Armed Services Blood Program (ASBP) enhanced LTOWB production at a conversion rate 2:1 from packed red blood cell to LTOWB. Consequently, there was a decline in expired blood products, and fulfillment rates for blood requests are projected to reach 100% consistently. This paper delves into the intricacies of the expeditionary blood supply, the rationale behind the LTOWB transition, the devised allocation strategy, and the subsequent impacts of this change.

Bipolar ablation involving coronary venous system for refractory left ventricular summit arrhythmias.

Background: Catheter ablation of premature ventricular complexes (PVCs) and ventricular tachycardia (VT) from the left ventricular summit (LVS) may require advanced ablation techniques. Bipolar ablation from the coronary veins and adjacent endocardial structures can be effective for refractory LVS arrhythmias. Objective: The aim of this study was to investigate the outcomes of bipolar ablation performed between the coronary venous system and adjacent endocardial left ventricular outflow tract (LVOT) or right ventricular outflow tract (RVOT). Methods: This multicenter study included consecutive patients with LVS PVC/VT who underwent bipolar ablation between the anterior interventricular vein (AIV) or great cardiac vein (GCV) and the endocardial LVOT/RVOT after failed unipolar ablation. Ablation was started with powers of 10-20 W and uptitrated to achieve an impedance drop of at least 10%. Angiography was performed in all cases to confirm a safe distance (>5 mm) of the catheter from the major coronary arteries. Results: Between 2013 and 2023, bipolar radiofrequency ablation between the AIV/GCV and the adjacent LVOT/RVOT was attempted in 20 patients (4 female; age 57 ± 16 years). Unipolar ablation from sites of early activation (AIV/GCV, LVOT, aortic cusps, RVOT) failed to effectively suppress the PVC/VT in all subjects. Bipolar ablation was delivered with a maximum power of 30 ± 8 W and total duration of 238 ± 217 s and led to acute PVC/VT elimination in all patients. No procedural-related complications occurred. Over a follow-up period of 30 ± 24 months, the freedom from arrhythmia recurrence was 85% (1 recurrence in the VT group and 2 in the PVC group). PVC burden was reduced from 22% ± 10% to 4% ± 8% (P <.001). Conclusion: In cases of LVS PVC/VT refractory to unipolar ablation, bipolar ablation between the coronary venous system and adjacent endocardial LVOT/RVOT is safe and effective if careful titration of power and intraprocedural angiography are performed to ensure a safe distance from the coronary arteries.

Aeromedical Evacuation, the Expeditionary Medicine Learning Curve, and the Peacetime Effect.

INTRODUCTION: Organizational proficiency increases with experience, which is known as a learning curve. A theoretical peacetime effect occurs when knowledge and skills degrade during peacetime. In this study, the intertheater evacuation system was examined for evidence of a military learning curve and peacetime effect. MATERIALS AND METHODS: Data on medical evacuations from U.S. Central Command occurring between January 1, 2003, and December 31, 2022, were acquired from the TRANSCOM Regulating and Command & Control Evacuation System. Priority mission evacuation time corresponding to peak periods of activity in Iraq and Afghanistan and minimal activity in Afghanistan was analyzed. Any reduction or increase in the delivery time of casualties would be considered a change in proficiency. RESULTS: There was a marginal monthly decline of 0.019 days (27.4 min) to perform a priority evacuation from Iraq (95% confidence interval [CI], 0.009 to 0.028 days, P < .001) and a decline of 0.010 days (14.4 min) from Afghanistan (95% CI, 0.003 to 0.016 days, P = .004) over 40 months from peak monthly average times. There was a monthly marginal increase in priority evacuation average time from Afghanistan of 0.008 days (11.5 min) (95% CI, 0.005 to 0.011, P < .001) between January 2013 and December 2020. The number of monthly evacuations estimated to maintain or improve monthly average evacuation time is approximately 50. CONCLUSIONS: An intertheater aeromedical evacuation system increased in proficiency during periods of conflict and declined during relative peacetime. There is evidence of a peacetime effect on intertheater aeromedical evacuation.

Geometric and Electronic Effects in the Binding Affinity of Imidazole-Based N-Heterocyclic Carbenes to Cu(100)- and Ag(100)-Based Pd and Pt Single-Atom Alloy Surfaces.

We have conducted nonlocal periodic density functional theory (DFT) calculations of N-heterocyclic carbenes (NHCs) adsorbed to Pd/Cu(100), Pt/Cu(100), Pd/Ag(100), and Pt/Ag(100) single atom alloys (SAAs) utilizing the nonlocal optPBE-vdW functional. NHCs with electron donating groups (EDGs) are predicted to bind more strongly to the SAA surface compared to NHCs functionalized with electron withdrawing groups (EWGs). Our calculations show that NHCs typically bind to SAA geometries containing a small space between the heteroatom sites for the SAAs considered. Generally, this pattern is predicted to persist for a single NHCs or for a pair of NHCs bound to the SAA surfaces. Approximate linear relationships between NMR-based parameters and NHC-SAA binding energies are uncovered. We predict that the binding of NHCs to SAA surfaces is composition-dependent and heteroatom geometry dependent.

The External Auditory Canal: Examination and Evaluation.

The external auditory canal is a highly specialized skin appendage whose primary purpose is to provide a pathway for the transmission of sound to the tympanic membrane and beyond. It is also a frequent source of symptoms for our patients. Sources of pain, hearing loss, tinnitus, itching, and other sensations can be inferred from an appropriate history. This should be followed by a thorough cleaning of the ear, so that a thorough examination can be performed.

Fungal Infections of the External Auditory Canal and Emerging Pathogens.

Fungal infections of the external auditory canal can range from common (otomycosis) to life threatening (necrotizing otitis externa). Proper identification of fungal pathogens is necessary to guide appropriate therapy, and a high index of suspicion for fungal causes of ear canal disease is critical. Fungal pathogens may be an especially important cause of ear canal disease in certain populations, including patients with diabetes, patients recently treated with antibiotics, and immunosuppressed patients. Opportunistic fungal infections of the ear canal are an emerging concern.

Follow the Wax: The Natural Protection of the Ear Canal and Its Biome.

The external canal is a unique environment that has an elaborate mechanism for self-cleaning and protection. The fundamental basis of this is the epithelial migration of the desquamating layers of the keratinizing epithelium that lines the entire canal and ear drum. This migratory movement results in a "conveyor belt" effect where the dead skin is moved out of the bony ear canal to the cartilaginous portion, where it is lifted off with the help of glandular skin secretions and the hairs of the canal to form what we call "ear wax." The ear wax has numerous protective properties and is essential to the health of the external ear. The protective properties are due to chemical properties of the wax, in addition to intrinsic chemical secretions by the sebaceous and cerumen apocrine glands. The protection also comes from a diverse population of organisms that exist in the external ear that are usually saprophytic, commensal, and symbiotic, but in some cases, they can become parasitic and pathologic. Detection and quantification of the members of this biome has been difficult, and their overall role in the normal biome of the ear and their transition into pathogens remain an area of active research and investigation.

Early veno-venous extracorporeal membrane oxygenation is an effective strategy for traumatically injured patients presenting with refractory respiratory failure.

BACKGROUND: Venovenous extracorporeal membrane oxygenation (VV ECMO) is used for respiratory failure when standard therapy fails. Optimal trauma care requires patients be stable enough to undergo procedures. Early VV ECMO (EVV) to stabilize trauma patients with respiratory failure as part of resuscitation could facilitate additional care. As VV ECMO technology is portable and prehospital cannulation possible, it could also be used in austere environments. We hypothesize that EVV facilitates injury care without worsening survival. METHODS: Our single center, retrospective cohort study included all trauma patients between January 1, 2014, and August 1, 2022, who were placed on VV ECMO. Early VV was defined as cannulation ≤48 hours from arrival with subsequent operation for injuries. Data were analyzed with descriptive statistics. Parametric or nonparametric statistics were used based on the nature of the data. After testing for normality, significance was defined as a p < 0.05. Logistic regression diagnostics were performed. RESULTS: Seventy-five patients were identified and 57 (76%) underwent EVV. There was no difference in survival between the EVV and non-EVV groups (70% vs. 61%, p = 0.47). Age, race, and gender did not differ between EVV survivors and nonsurvivors. Time to cannulation (4.5 hours vs. 8 hours, p = 0.39) and injury severity scores (34 vs. 29, p = 0.74) were similar. Early VV survivors had lower lactic acid levels precannulation (3.9 mmol/L vs. 11.9 mmol/L, p < 0.001). A multivariable logistic regression analysis examining admission and precannulation laboratory and hemodynamic values demonstrated that lower precannulation lactic acid levels predicted survival (odds ratio, 1.2; 95% confidence interval, 1.02-1.5; p = 0.03), with a significant inflection point of 7.4 mmol/L corresponding to decreased survival at hospital discharge. CONCLUSION: Patients undergoing EVV did not have increased mortality compared with the overall trauma VV ECMO population. Early VV resulted in ventilatory stabilization that allowed subsequent procedural treatment of injuries. LEVEL OF EVIDENCE: Therapeutic Care/Management; Level III.

Catheter ablation of intramural outflow tract premature ventricular complexes: a multicentre study.

AIMS: Ablation of outflow tract ventricular arrhythmias may be limited by a deep intramural location of the arrhythmogenic source. This study evaluates the acute and long-term outcomes of patients undergoing ablation of intramural outflow tract premature ventricular complexes (PVCs). METHODS AND RESULTS: This multicenter series included patients with structurally normal heart or nonischemic cardiomyopathy and intramural outflow tract PVCs defined by: (a) ≥ 2 of the following criteria: (1) earliest endocardial or epicardial activation < 20ms pre-QRS; (2) Similar activation in different chambers; (3) no/transient PVC suppression with ablation at earliest endocardial/epicardial site; or (b) earliest ventricular activation recorded in a septal coronary vein. Ninety-two patients were included, with a mean PVC burden of 21.5±10.9%. Twenty-six patients had had previous ablations. All PVCs had inferior axis, with LBBB pattern in 68%. In 29 patients (32%) direct mapping of the intramural septum was performed using an insulated wire or multielectrode catheter, and in 13 of these cases the earliest activation was recorded within a septal vein. Most patients required special ablation techniques (one or more), including sequential unipolar ablation in 73%, low-ionic irrigation in 26%, bipolar ablation in 15% and ethanol ablation in 1%. Acute PVC suppression was achieved in 75% of patients. Following the procedure, the PVC burden was reduced to 5.8±8.4%. The mean follow-up was 15±14 months and 16 patients underwent a repeat ablation. CONCLUSION: Ablation of intramural PVCs is challenging; acute arrhythmia elimination is achieved in 3/4 patients, and non-conventional approaches are often necessary for success.

Deductive Electrocardiographic Analysis of Left Ventricular Summit Arrhythmias.

The left ventricular summit is a source of idiopathic ventricular arrhythmias and presents distinct challenges for mapping and ablation. These arrhythmias are typically targeted from the distal coronary venous system or most often from endocardial vantage points such as the left coronary cusp, basal left ventricle or septal right ventricular outflow tract. In this article, we review the electrocardiographic patterns that suggest a possible origin from the left ventricular summit and the features that may help to predict the most likely site of successful ablation.

Surgical Capability Utilization Time for Military Casualties at Role 2 and Role 3 Facilities.

INTRODUCTION: Operative capability utilization time for casualties is an important metric for trauma planning in the military. Operative capabilities can be a choke point resulting in multiple patients waiting for the asset to become available during mass casualty events. The objective measurement of how long deployed operative capabilities are utilized for various categories of injury has not been described. This study provides the measurements for role 2 and role 3 facilities. MATERIALS AND METHODS: The Department of Defense Trauma Registry was sampled for each composite injury severity score (ISS) category in the registry (mild, moderate, severe, and critical). Thirty randomly selected samples for role 2 and role 3 facilities for each composite ISS category with an anesthesia record including a start and end time for the index surgical case were included. RESULTS: There were no statistical differences between role 2 and role 3 facility operative capability utilization times for any composite ISS category. The mean time (min) for mild, moderate, severe, and critical for role 2 and role 3 was 93.9 and 96.3, 142.2 and 144.3, 177.4 and 171.1, 182.9 and 205.6, respectively. The proportion of Department of Defense Trauma Registry surgical patients who were mild, moderate, severe, or critical were 57.5%, 18.2%, 13.6%, and 10.7%, respectively. CONCLUSION: There is no statistical difference between roles of care in operative asset utilization time. The provided operative capability utilization times will be useful for casualty management planning and improvement initiatives.

Impact of bundle branch block morphology on outcomes of patients with syncope and bifascicular block: A SPRITELY (POST 3) substudy.

BACKGROUND: Permanent pacing is often considered for patients with syncope and bifascicular block. OBJECTIVE: The purpose of this study was to determine whether QRS morphology or other electrocardiographic characteristics can identify patients who may benefit from permanent pacing. METHODS: The Syncope: Pacing or Recording in the Later Years (SPRITELY) trial was a multicenter trial that randomized patients with bifascicular block and syncope (n = 115) to empiric pacemaker implantation vs implantable loop recorder (ILR) monitoring. In this SPRITELY subanalysis, baseline 12-lead electrocardiograms were evaluated for bundle branch block (BBB) morphology, QRS width, and PR and QT intervals and their impact on clinical outcomes was assessed. RESULTS: There were 41 patients with left BBB (36%), 69 patients with right bundle branch block (RBBB) and left anterior fascicular block (60%), and 5 patients with RBBB and left posterior fascicular block (4%). Pacemaker implant compared with ILR was associated with a significant reduction of major study-related events (MSREs) in both patients with left BBB (23.8% vs 78.9%; P = .001) and those with RBBB (27% vs 72.9%; P < .0001). Similarly, a reduction of MSREs was observed in both patients with trifascicular block (23% vs 84.6%; P < .0001) and those with bifascicular block (26.6% vs 68.9%; P = .002). In the group randomized to ILR monitoring, the type of BBB was not a predictor of recurrent syncope (P = .30), bradycardia requiring pacemaker (P = .15), or MSREs (P = .42). The presence of PR interval prolongation or QRS width in this group did not predict MSREs (P = .22 and P = .96, respectively). CONCLUSION: In patients with syncope and bifascicular block, pacemaker implantation reduces adverse events as compared with ILR monitoring, irrespective of the type of BBB or the presence of PR interval prolongation.

Half-Normal Saline vs Normal Saline for Cavotricuspid Isthmus-Dependent Atrial Flutter Ablation.

Background: Cavotricuspid isthmus (CTI) ablation requires permanent bidirectional block to prevent recurrence of typical atrial flutter (AFL). Catheter irrigation with half-normal saline (HNS) produces larger and deeper lesions in experimental models compared with normal saline (NS). This study was performed to compare the clinical efficacy and safety of HNS vs NS irrigation for typical AFL ablation. Methods: Sixty patients undergoing catheter ablation of typical AFL were randomized 1:1 to NS or HNS irrigation. Endpoints included time to CTI block, acute reconnection, incidence of steam pops, and recurrence of AFL during follow-up. Results: Baseline characteristics were comparable between both arms. The mean age of the patients was 68.5 ± 8.2 years, 20% were female, and 32% had atrial fibrillation before being enrolled. Bidirectional CTI block was obtained in all patients with no difference in time to CTI block between groups (6.4 ± 4.4 minutes vs 7.6 ± 4.5 minutes, respectively; P = 0.15). There was a trend to less acute reconnection in the HNS group compared with NS (13.3% vs 26.6%; P = 0.46). Steam pops occurred in 4 patients using HNS vs none in the NS group, but no major complications were observed. During the follow-up, rate of AFL recurrence was similar between groups (6.7% with HNS vs 10% with NS; P = 0.5). There was no difference in time to recurrence (7.6 ± 6.9 vs 4.9 ± 4.5 months; P = 0.6). Conclusions: In this small pilot randomized controlled trial, there was no significant difference between HNS and NS for CTI ablation; however, HNS may increase the incidence of steam pops.

Contexte: Pour prévenir la récurrence d'un flutter auriculaire (flutter) typique, l'ablation de l'isthme cavotricuspidien exige un bloc de conduction bidirectionnel permanent. Dans des modèles expérimentaux, l'irrigation par cathéter au moyen d'un soluté demi-salin produit des lésions plus larges et plus profondes, comparativement à un soluté physiologique salin. La présente étude a été réalisée dans le but de comparer l'efficacité clinique et l'innocuité de l'irrigation au moyen d'un soluté demi-salin à celles de l'irrigation par un soluté physiologique salin dans les cas d'ablation d'un flutter. Méthodologie: Soixante patients soumis à une ablation d'un flutter typique par cathéter ont été répartis au hasard dans un rapport de 1:1 en deux groupes d'irrigation, soit par soluté demi-salin, soit par soluté physiologique salin. Les critères d'évaluation de l'étude étaient les suivants : temps écoulé jusqu'au bloc de l'isthme cavotricuspidien, reconnexion aiguë, jet de vapeur sonore (steam pop) et récidive de flutter durant le suivi. Résultats: Les caractéristiques initiales étaient comparables dans les deux groupes. Les patients avaient une moyenne d'âge de 68,5 ± 8,2 ans, 20 % étaient des femmes et 32 % présentaient une fibrillation auriculaire avant leur admission à l'étude. Un bloc bidirectionnel dans l'isthme cavotricuspidien a été obtenu chez tous les patients, sans différence entre les groupes en ce qui a trait au temps écoulé jusqu'à l'obtention du bloc isthmique (6,4 ± 4,4 minutes vs 7,6 ± 4,5 minutes, respectivement; p = 0,15). Une tendance vers un nombre plus faible de cas de reconnexion aiguë a été notée dans le groupe d'irrigation par soluté demi-salin, comparativement au soluté physiologique salin (13,3 % vs 26,6 %; p = 0,46). Un jet de vapeur sonore est survenu chez 4 patients recevant un soluté demi-salin contre aucun dans le groupe sous soluté physiologique salin, mais aucune complication importante n'a été relevée. Durant le suivi, le taux de récidive de flutter a été similaire dans les deux groupes (6,7 % sous soluté demi-salin vs 10 % sous soluté physiologique salin; p = 0,5). Aucune différence n'a été notée pour ce qui est du temps écoulé jusqu'à la survenue d'une récidive (7,6 ± 6,9 vs 4,9 ± 4,5 mois; p = 0,6). Conclusions: Dans cette petite étude pilote contrôlée et avec répartition aléatoire, aucune différence significative n'a été observée entre le soluté demi-salin et le soluté physiologique salin pour l'ablation de l'isthme; toutefois, le soluté demi-salin augmenterait la fréquence des cas de jet de vapeur sonore.

Coupled local mode method for simulating vibrational spectroscopy.

Experimental and theoretical studies have highlighted protonated water clusters (PWCs) as important models of the excess proton in aqueous systems. A significant focus has been characterizing the spectral signatures associated with different excess proton solvation motifs. Accurate vibrational frequency calculations are crucial for connecting the measured spectra to the structure of PWCs. In this paper, we extend and characterize a coupled local mode (CLM) approach for calculating the infrared spectra of PWCs using the H+(H2O)4 cluster as a benchmark system. The CLM method is relatively low cost and incorporates the anharmonicity and coupling of OH vibrations. Here, we demonstrate the accuracy of the technique compared to experiments. We also illustrate the dependence of calculated spectral features on the underlying electronic structure theory and basis sets used in the local mode frequency and coupling calculations.