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The excitation of Rayleigh surface waves by an interdigital transducer (IDT) on a piezoelectric layered structure has been studied in this paper. The surface wave velocity, optimum finger width, and number of fingers for maximum bandwidth for the IDT have been calculated for several values of the product (ks) of wavenumber and layer thickness. The frequency response and equivalent circuit of the IDT have been determined. Numerical examples are also presented and discussed. Subject Classification: 20.15. [ABSTRACT FROM AUTHOR]

Background: Cardiac troponin (cTn) can also be elevated in patients with non-cardiac illnesses. The utility of elevated cTn in patients with acute gastrointestinal bleeding (AGIB) is unclear. Methods: We retrospectively identified all patients admitted with AGIB who had cTn ordered. We assessed the prevalence, predictors and mortality. Results: A total of 172 patients with AGIB were included in the study, of whom 17% had abnormal cTn. Predictors of elevated cTn were advanced age, lower BMI, coronary artery disease and chronic kidney disease. The abnormal cTn group had more cardiac consultation and procedures and longer length of stay. However, there was no difference in mortality between the two groups. Conclusion: Elevated cTn in patients with AGIB was associated with more cardiology consultation and downstream cardiac testing, greater delay to endoscopic evaluation and longer length of stay, without significantly affecting the mortality.

Atrial fibrillation (AF) and cerebral amyloid angiopathy (CAA) present risks of ischemic stroke and intracerebral hemorrhage (ICH). Vitamin K antagonist use is associated with fluctuations in international normalized ratio (INR), which predispose to a higher bleeding risk. Patients with a diagnosis of AF and ICH while on a vitamin K antagonist were identified using the Rochester Epidemiology Project. Sixty patients were identified (mean age 81.3 years; 24 men). Thirty-three (55%) exhibited characteristics consistent with possible (n = 25) or probable (n = 8) CAA. Mean time in therapeutic range in the 30 days preceding ICH was 55.4%, with no difference between CAA and non-CAA patients. Mean time spent above therapeutic range (INR > 3.0) was 17.7%, with no difference between CAA and non-CAA patients. Following ICH, 21 (35%) died within 30 days, with total mortality at 76.7% after 176.4 person-years of follow-up (mean 2.9 years). Time in therapeutic range in the 30 days prior to ICH had no significant impact on 7-day mortality, nor risk of recurrent ICH or ischemic stroke. Patients with warfarin-related ICH were often outside of the therapeutic range within the month preceding hemorrhage but more frequently were subtherapeutic. Even with careful avoidance of supratherapeutic INR, vitamin K antagonist use in CAA patients is unlikely to have a major effect in preventing ICH and must be used with caution., (Copyright © 2021 Baylor University Medical Center.)

The Watchman device (WD) is a commonly used alternative strategy to oral anticoagulation for stroke risk reduction in patients with atrial fibrillation who have an increased bleeding risk. There are rare case reports of WD-related infection. Currently, there is no formal study that has systematically evaluated the incidence and outcomes WD-related infections. The objective of this study was to evaluate the incidence, risk factors, and outcomes for WD-associated infections in a single-center cohort over a 14-year period. All patients who underwent WD implantation over a 14-year study period (July 2004 through December 2018) comprised our cohort. Baseline characteristics, procedural data, and postimplantation events were identified through a retrospective chart review. Primary study outcomes included WD-related infection, other cardiovascular device-related infection, bacteremia, and mortality. A total of 181 patients (119 males; 65.7%) with a mean age of 75 years at implantation were included in the analysis. A total of 534.7 patient years of follow-up was accrued, with an average of 2.9 years per patient. The most common indications for implantation included gastrointestinal bleeding (56 patients; 30.9%) and intracerebral bleeding (51 patients; 28.2%). During the follow-up period, 37 (20.4%) patients died. Six developed evidence of bacteremia. Only 1 developed an implantable cardioverter defibrillator infection that required a complete system extraction. None of the cohort developed a WD-related device infection during the study period. We concluded that there is a low risk of WD-related infection even in the setting of a blood stream infection., Competing Interests: R.C.W.: Mayo Clinic, Fellow. T.M.: Mayo Clinic, Resident. F.A.: Mayo Clinic, Resident. S.P.: Creighton University, Fellow. S.J.A.: Mayo Clinic, Professor of Medicine; royalties for work licensed through the Mayo Clinic to a privately held company for contributions related to the use of nerve signal modulation to treat central, autonomic, and peripheral nervous system disorders, including pain. The Mayo Clinic received royalties from and owns equity in this company and is copatent holder for a technique to minimize coagulum formation during radiofrequency ablation. Products or techniques related to the above disclosures are not discussed in this paper. Honoraria/speaker: Atricure, Biotronik, Boston Scientific, Medtronic, Abbott, Zoll, and Johnson & Johnson. L.M.B.: Mayo Clinic, Professor Emeritus of Medicine, supplemental employee; royalty payments (authorship duties): UpToDate, Inc.; consultant duties: Boston Scientific Corp., Botanix Pharmaceuticals Inc., and Roivant Sciences Inc. D.R.H.: Mayo Clinic, Professor of Medicine. D.C.D.: Mayo Clinic, Associate Professor of Medicine. C.V.D.: Mayo Clinic, Associate Professor of Medicine., (Copyright © 2021 by S. Karger AG, Basel.)

Objective: To determine the utility of the HAS-BLED (Hypertension, Abnormal renal/liver function, Stroke, Bleeding history or predisposition, Labile international normalized ratio, Elderly, Drugs/alcohol concomitantly) and CHA 2 DS 2 -VASc (Congestive heart failure, Hypertension, Age, Diabetes, previous Stroke/transient ischemic attack-VAScular disease) scores among patients on anticoagulation (AC) therapy for atrial fibrillation (AF) who have evidence of cerebral amyloid angiopathy (CAA)., Patients and Methods: Patients older than 55 years with a diagnosis of AF who had a nontraumatic intracerebral hemorrhage (ICH) while on AC therapy between 1995 and 2016 were identified using the Rochester Epidemiology Project Database. Medical records were reviewed, including imaging of the brain, to identify baseline characteristics, AC use, and outcomes., Results: A total of 65 patients were identified (mean age, 81.3 years); 35 (53.8%) had evidence of possible/probable CAA. Mean HAS-BLED score in the CAA group was significantly lower (2.1) than that of the non-CAA group (2.9; P<.001). Mortality after ICH, adjusted for HAS-BLED scores, was not significantly different among patients with and without CAA. Sixteen patients restarted on AC therapy after ICH; CHA 2 DS 2 -VASc scores were no different between this group and those who were not restarted. Among patients with CAA, the overall rate of ICH recurrence was 8.6% over 93.5 person-years of follow-up. Among patients with CAA, the rate of ICH recurrence was 3.2 per 100 patient-years, higher than their HAS-BLED scores would predict (1.9 bleeds/100 patient-years)., Conclusion: HAS-BLED scores were lower in patients who had evidence of CAA compared with those without, suggesting underestimation of ICH risk in patients with CAA. CHA 2 DS 2 -VASc scores did not affect resumption of AC therapy. ICH recurrence was higher in patients with CAA than their HAS-BLED scores predicted. Current risk assessment scoring systems do not accurately account for CAA in patients with AF on AC., (Copyright © 2020 Mayo Foundation for Medical Education and Research. Published by Elsevier Inc. All rights reserved.)

Purpose: To determine anti-HCV antibodies and genomic subtype of HCV in 1487 confirmed human immunodeficiency virus (HIV) positive samples., Methods: A total of 1487 confirmed HIV-positive samples were tested for anti-HCV antibodies by using a third generation ELISA kit (Ortho 3.0) and by RT PCR for HCV. HIV and HCV coinfected samples were selected for HCV genotyping by RFLP and subtyping with NS5-type specific primers., Results: A total of 1487 HIV-infected serum samples were screened for HCV infection, of which, a 1443 (97.04%) were negative and 45 (3.02%) were coinfected. HIV-HCV coinfection was predominant in the age group 41-50 years (51.1%). HCV genotyping and subtyping was done for the 45 HCV RNA-positive specimens of which genotype 1 was observed in 31 (68.8%) and genotype 3 was observed in 14 (31.1%) subjects. Further subtyping analysis showed the genotype 1b in 23 (51.1%), 1a in eight (17.7%), 3a in 10 (22.2%) and 3b in four (8.8%) subjects., Conclusion: HIV and HCV seroprevalence is higher in South India, and the most prevalent genotype in coinfection was genotype 1b.

Laboratory diagnosis is the mainstay in the diagnosis of HIV infection in an individual. The wide range of diagnostic kits available, for the detection of anti HIV antibodies, makes it mandatory that the kits are evaluated before they are made available in the market. We evaluated the performance of a Microlisa HIV kit (J. Mitra & Co.) using a panel of HIV reactive and non reactive clinical specimens. The sensitivity and specificity of the kit were found to be 100% as compared to the UBI HIV 1/2 EIA kit. The ease of testing, the assay characteristics including efficiency of the Microlisa favour its use by laboratories as a primary screen for HIV infection.