Streptococcus agalactiae infective endocarditis in Canada: a multicenter retrospective nested case control analysis

Background Infective endocarditis (IE) caused by Streptococcus agalactiae (GBS) is increasingly reported and associated with an aggressive course and high mortality rate. Existing literature on GBS IE is limited to case series; we compared the characteristics of patients with GBS IE to patients with GBS bacteremia without IE to identify risk factors for development of IE. Methods A nested case–control study in a cohort of adult patients with GBS bacteremia over a 18-year period was conducted across seven centres in three Canadian cities. A chart review identified patients with possible or definite IE (per Modified Duke Criteria) and patients with IE were matched to those without endocarditis in a 1:3 fashion. Multivariate analyses were completed using logistic regression. Results Of 520 patients with GBS bacteremia, 28 cases of possible or definite IE were identified (5.4%). 68% (19/28) met criteria for definite IE, surgery was performed in 29% (8/28), and the overall in-hospital mortality rate was 29% (8/28). Multivariate analysis demonstrated that IE was associated with injection drug use (OR = 19.6, 95% CI = 3.39–111.11, p = 0.001), prosthetic valve (OR = 11.5, 95% CI = 1.73–76.92, p = 0.011) and lack of identified source of bacteremia (OR = 3.81, 95% CI = 1.24–11.65, p = 0.019). Conclusions GBS bacteremia, especially amongst people who inject drugs, those with prosthetic valves, and those with no apparent source of infection, should increase clinical suspicion for IE.

Loss of engagement in controlling chronic anticoagulation therapy during Covid-19 stringency measures. A single center experience of disproportioned increase of stuck mechanical valves

Stuck valve is a very rare and severe complication that occurs in mechanical valve replacement patients with ineffective anticoagulation. However, with COVID-19 restriction measures, it became challenging to regularly assess INR to make sure it falls within the target therapeutic range to prevent this complication. We present a series of 10 patients who either underwent transthoracic echocardiography for a suspected stuck valve or were seen at the outpatient valve clinic with the residual consequences of a stuck valve during the COVID-19 restriction measures in our institute. Stuck prosthetic valves incident has increased significantly during this period, particularly those in the mitral position for which urgent replacement and prolonged hospitalization were necessary. Particularly with the COVID-19 restrictions in place, these cases highlight the need for physicians to be aware of the dramatic increase in the incidence of stuck prosthetic valves in patients on chronic warfarin therapy.

Left Ventricular Systolic Dysfunction Due to Atrial Fibrillation: Clinical and Echocardiographic Predictors

Background: Diagnosis of AF-induced cardiomyopathy can be challenging and relies on ruling out other causes of cardiomyopathy and, after restoration of sinus rhythm, recovery of left ventricular (LV) function. The aim of this study was to identify clinical and echocardiographic predictors for developing cardiomyopathy with systolic dysfunction in patients with atrial tachyarrhythmia. Methods: This retrospective study was conducted in a large tertiary care centre and compared patients who experienced deterioration of LV ejection fraction (EF) during paroxysmal AF, demonstrated by precardioversion transoesophageal echocardiography with patients with preserved LV function during AF. All patients had documented preserved LVEF at baseline (EF >50%) while in sinus rhythm. Results: Of 482 patients included in the final analysis, 80 (17%) had reduced and 402 (83%) had preserved LV function during the precardioversion transoesophageal echocardiography. Patients with reduced LVEF were more likely to be men and to have a more rapid ventricular response during AF or atrial flutter (AFL). A history of prosthetic valves was also identified as a risk factor for reduced LVEF. Patients with reduced LVEF also had higher incidence of tricuspid regurgitation and right ventricular dysfunction. Conclusion: In ‘real-world’ experience, male patients with rapid ventricular response during paroxysmal AF or AFL are more prone to LVEF reduction. Patients with prosthetic valves are also at risk for LVEF reduction during AF/AFL. Finally, tricuspid regurgitation and right ventricular dysfunction may indicate relatively long-standing AF with an associated reduction in LVEF.

Fabricating a Low-cost and Low-immune Xenogeneic Aortic Valve Bio Prosthesis

BackgroundCardiac valve replacement is the only available treatment for end-stage valvular dysfunction patients. In this treatment, among the available choices of valves, the bio-prosthetic valves are better than the mechanical ones in terms of hemodynamic and infection-resistant properties. However, they tend to fail with time, posing a catastrophic event. This study focuses on fabricating the heart valve to eliminate the flaws of bio-prosthetic valves. MethodsPerfusion-based decellularization method was adapted for decellularisation to the sheep heart. Further, decellularised aortic valves were cross-linked with 0.2% Glutaraldehyde (Group C). ResultsAll valves were tested for biochemical and molecular assays including biomechanical tensile testing. Histology, SEM showed a complete lack of cells with intact matrix for decellularised groups. The fibrin glue coated valves leaflet scaffolds showed remodeling of the cells as per the matrix (plasticity). Characterization studies emphasized the cellular behaviour onto matrigel assay, live-dead assay, and the expression of vWF, glycocalyx lectin. ConclusionsThis study focuses on fabricating a re-endothelialized xenogeneic aortic valve leaflet using cross-linking reaction to mask antigenicity of the host proteins (low-immune humanized) and avoid post-implantation cross-reaction.

Cardiovascular disease

This chapter describes the anaesthetic management of the patient with cardiovascular disease. The topics include ischaemic heart disease (including perioperative myocardial infarction and percutaneous coronary intervention), valvular heart disease (incuding prosthetic valves), congenital heart disease, cardiomyopathy, pericardial disease, the patient with a transplanted heart, narrow complex arrhythmias, broad complex arrhythmias and heart block. For each topic, pre-operative investigation and optimisation, treatment, and anaesthetic management are described including peri-operative management of pre-existing arrhythmias (such as atrial fibrillation), and the patient with an implanted pacemaker or defibrillator.

Transcatheter Aortic Valve Dislocation into the Left Ventricle Caused by the Watermelon Effect

Transcatheter aortic valve implantation (TAVI) is a well-established method for treating severe aortic stenosis. Prosthetic valve dislocation immediately after deployment is a rare and feared complication. We present a case of a patient with severe, symptomatic aortic stenosis who was admitted for TAVI. During balloon inflation the valve (Edwards SAPIEN XT) dislocated into the left ventricle as a result of the watermelon effect caused by a narrow, severely calcified sino-tubular junction. A second valve of the same type and size was immediately implanted in a suboptimal position in order to reduce severe aortic regurgitation. This facilitated the use of veno-arterial extracorporeal membrane oxygenation support (V-A ECMO). The patient was thereafter stabilized and transferred for urgent surgery, where both prosthetic valves were removed. The aortic valve was replaced with an additional reconstruction of the ascending aorta.

Exploration for Thermostable β-Amylase of a Bacillus sp. Isolated from Compost Soil to Degrade Bacterial Biofilm

More than 85% of nosocomial infections are due to the development of bacterial biofilms. Recent research proposed that biofilm-like structures are not only visible in autopsies, biopsies, patients with chronic wounds, and exudates in animal models but are also present in biomedical devices, implants, prosthetic valves, urinary catheters, etc.

Factors determining mitral valve dysfunction in patients who underwent surgical mitral valve replacement with bio-prosthetic valves

Background There is increasing Interest in bio-prosthetic MVD as recent advances in transcatheter MV interventions, but there is limited data. Objectives The aim of this study was to identify the factors determining mitral valve (MV) dysfunction (MVD) in patients who underwent MV replacement with bio-prosthetic valves. Also, we sought to investigate clinical outcomes in patients with bio-prosthetic MVD. Methods A total of 233 patients underwent surgical bio-prosthetic MV replacement between June 1996 and May 2015. Finally, 226 patients (mean age 66.9±11.5 years, 74.3% of women) were analyzed, excluding patients who followed-up for less than 5 years and patients whose baseline or follow-up echocardiography could not be analyzed. Clinical, echocardiographic, and laboratory data were collected early after the surgery and during follow-up. MVD was defined as an increase in mean gradient ≥5 mmHg with leaflet motion limitation and/or newly developed MV regurgitation during follow-up. Clinical outcome was defined as a composite of cardiovascular death, redo MV surgery or intervention, and hospitalization for heart failure. Results During a median of 102.0 months (interquartile range 72.0 to 132.0 months), 65 patients (28.8%) revealed MVD. 8 (12.3%) patients revealed predominant MV obstruction, and 57 (87.7%) showed predominant MV regurgitation. Factors associated with bio-prosthetic MVD by multivariate regression analysis were young age at operation (hazard ratio 0.97, 95% CI 0.95–0.99, p=0.001), end-stage renal disease (hazard ratio 4.29, 95% CI 1.45–12.71, p=0.007), elevated mean diastolic pressure gradient>5.5 mmHg across the bio-prosthetic MV early after operation (hazard ratio 1.86, 95% CI 0.97–3.74, p=0.063) and anemia after operation (hazard ratio 0.84, 95% CI 0.74–0.95, p=0.007). However, the presence of hypertension, dyslipidemia, or porcine bio-prosthesis was not related to the bio-prosthetic MVD. Kaplan-Meier curves revealed significant differences in event-free survivals for the occurrence of bio-prosthetic MVD according to each factor (Figure 1). Patients with bio-prosthetic MVD showed significantly poor clinical outcomes compared with those without bio-prosthetic MVD (event-free survival 43.1% vs. 91.9%, log-rank p<0.001) during the follow-up. Conclusions Young age at operation, end-stage renal disease, elevated mean pressure gradient early after the operation, and anemia after operation were associated with bio-prosthetic MVD in patients who underwent bio-prosthetic MV replacement. FUNDunding Acknowledgement Type of funding sources: None.