ZIKV Envelope Domain-Specific Antibodies: Production, Purification and Characterization

Infection with Zika virus (ZIKV) came first to public attention after it was found to be associated with congenital microcephaly during the outbreak in Brazil (2015–2016). Diagnosis of ZIKV suffers from extensive cross-reactivity with other Flaviviruses, which are circulating in many ZIKV epidemic areas. Due to the fatal outcome of ZIKV infection during pregnancy, detailed knowledge about neutralizing and non-neutralizing epitopes is crucial for the development of robust detection systems of protective antibodies. Therefore, additional information about ZIKV immunogenicity and antibody response is required. In this project, we report the production, purification and characterization of six different polyclonal antibodies against ZIKV envelope (E) protein. The produced antibodies bind to isolated ZIKV E protein as well as to the surface of ZIKV particles, interestingly without being potently neutralizing. Surface plasmon resonance measurement showed that these antibodies bind with high affinity to ZIKV E protein. Epitope mapping revealed that the epitopes are distributed among the three ZIKV E domains with seven binding sites. These identified binding sites overlap only partially with the previously described epitopes recognized by neutralizing antibodies, which is in accordance with their lack of potent neutralizing activity. Additionally, these antibodies showed neither cross-reactivity nor potent neutralizing activity against West Nile virus, a related flavivirus. The gained set of data helps to extend our understanding about the distribution of neutralizing and non-/weak-neutralizing epitopes in ZIKV E protein, and provides a rationale for ZIKV vaccine design and development of robust detection assays for neutralizing antibodies

Deep Y-descent in right atrial waveforms following left ventricular assist device implantation: Deep Y-descent in LVAD

© 2020 Elsevier Inc. Background: Characterization of right heart catheterization (RHC) waveforms provides diagnostic and clinical information in heart failure patients. We aimed to investigate the implication of RHC waveforms, specifically the y-descent, in patients with left ventricular assist device (LVAD). Methods and Results: Patients underwent RHC and waveforms were quantified prior to and 6 months after LVAD implantation. The impact of a deep y-descent ( \u3e 3 mmHg) on echocardiographic measures of right heart function and 1-year hemocompatibility-related adverse event rates were investigated. Eighty-nine patients (median 59 years old, 65 male) underwent RHC. RHC waveform showed unique changes following LVAD implantation, particularly an increase in the steepness of the y-descent. A post-LVAD deep y-descent was associated with reduced right ventricular function and enlarged right heart. Patients with post-LVAD deep y-descent had higher rates of gastrointestinal bleeding (0.866 vs 0.191 events/year) and stroke (0.199 vs 0 events/year) compared with those without (P \u3c . 05 for both). Conclusion: RHC waveforms characterized by deep y-descent on RHC waveform during LVAD support was associated with impaired right ventricular function and worse clinical outcomes

Estimation of the severity of aortic insufficiency by HVAD flow waveform

© 2020 The Society of Thoracic Surgeons Purpose: Aortic insufficiency (AI) significantly affects morbidity and mortality in patients with left ventricular assist devices. Although AI may be commonly assessed by echocardiography, expert techniques are required for accurate quantification of AI severity. Description: In this prospective blinded study, screenshots from the HVAD (Medtronic, Framingham, MA) display and simultaneous echocardiographic measurements were obtained. Each screenshot was digitized and the early diastolic phase slope was calculated, with blinding to the echocardiographic results. The regurgitant fraction of AI was quantified by Doppler echocardiography of the outflow graft. Evaluation: A total of 30 patients (median, 57 years old; 57% male) were enrolled. A cutoff of −17.6 L/min/s for the early diastolic phase slope had a sensitivity of 0.92 and a specificity of 0.53 to estimate significant AI with a regurgitant fraction of 30% or greater, and it significantly stratified patients into a low regurgitant faction group (0.3%) and a high regurgitant fraction group (33.0%) (P =.009). The early diastolic phase slope had a moderate correlation with the actually measured regurgitant fraction (r =.50). Conclusions: The early diastolic phase slope of the HVAD flow waveform may be a parameter that can estimate the presence of clinically significant AI

Decoupling between diastolic pulmonary artery and pulmonary capillary wedge pressures is associated with right ventricular dysfunction and hemocompatibility-related adverse events in patients with left ventricular assist devices

Background Decoupling between diastolic pulmonary artery pressure and pulmonary capillary wedge pressure is an index of pulmonary vascular damage. This study assessed the impact of decoupling on right heart function and hemocompatibility-related adverse events. Methods and Results In this prospective study, patients underwent invasive hemodynamic tests following left ventricular assist device implantation. Decoupling was defined as a difference of \u3e 5 mm Hg between diastolic pulmonary artery pressure and pulmonary capillary wedge pressure. Among 92 patients with left ventricular assist devices (median age, 61 years; 57% male), 44 patients (48%) had decoupling. Right heart function and size by echocardiographic assessment worsened during a 1-year observational period in the decoupling group as compared with the control group (P \u3c 0.05). The decoupling group had significantly lower 1-year freedom from any hemocompatibility-related adverse events (49% versus 79%; P=0.005), as well as a higher hemocompatibility score (2.14 versus 0.67; P=0.004). The scoring system depicts the severity of hemocompatibility-related adverse events using 4 escalating tiers. Increased tier I scores (1-2 gastrointestinal bleedings or medically managed pump thrombosis; P=0.027) and tier IIIB scores (disabling stroke or hemocompatibility-related adverse event-related death; P=0.041) occurred more frequently in the decoupling group. Conclusions The presence of decoupling between diastolic pulmonary artery pressure and pulmonary capillary wedge pressure was associated with worsening of right heart function and hemocompatibility-related adverse events in patients with left ventricular assist devices

Discordance between lactic acidemia and hemodynamics in patients with advanced heart failure

BACKGROUND: Elevated lactic acid (LA) levels carry a poor prognosis in patients with shock. Data are lacking on the significance of LA levels in patients with acute decompensated heart failure (ADHF). HYPOTHESIS: This study assessed the relationship between LA levels, hemodynamics and clinical outcomes. METHODS: This was a retrospective analysis of registry data of 100 advanced heart failure patients presenting for right heart catheterization (RHC) for concern of ADHF. LA levels (normal ≤2.1 mmol/L) were obtained prior to RHC; no significant changes in therapy were made between LA collection and RHC. RESULTS: Median age was 58 (47.3, 64.8) years; 57% were receiving inotropes prior to RHC. Median pulmonary capillary wedge pressure (PCWP) and cardiac index (CI) were 28 (21, 35) mmHg and 2.0 (1.7, 2.5) L/min/m2 , respectively. Eighty patients had normal LA prior to RHC. There was no correlation between LA levels and PCWP (R = 0.09, p = .38); 63% of the normal LA group had a PCWP \u3e24 mmHg. There was a moderate inverse correlation between LA and CI (R = - 0.40; p \u3c .001); 58% of the normal LA group had a CI \u3c2.2 L/min/m2 . Thirty-day survival free of death/hospice, inotrope dependence, progression to heart transplant/left-ventricular assist device implant was comparable between the normal and elevated LA groups (28% vs. 20%; p = .17). CONCLUSION: In patients presenting with ADHF, normal LA levels do not exclude the presence of depressed CI (a hemodynamic criteria for cardiogenic shock) and may not offer accurate risk stratification. Invasive hemodynamics should not be delayed based on normal LA levels alone

Effect of concomitant tricuspid valve surgery with left ventricular assist device implantation

© 2020 The Society of Thoracic Surgeons Background: Tricuspid regurgitation (TR) is common in advanced heart failure (HF) patients. However, the effect of concomitant tricuspid valve repair or replacement (tricuspid valve intervention [TVI]) with left ventricular assist device (LVAD) implantation is controversial. The aim of this study was to investigate the longitudinal trend of TR after LVAD implantation and the effect of TVI on the TR trend and clinical outcomes. Methods: We retrospectively reviewed patients at our institution who underwent LVAD implantation between April 2014 and August 2018. We evaluated the grade of TR by echocardiography before and after LVAD implantation. Moderate or greater TR was defined as significant. Results: Among 199 consecutive patients, 194 had at least 2 echocardiographic TR assessments before and after LVAD implantation. Of these patients, 108 were included in the TVI-positive (TVI+) group and 86 in the TVI-negative (TVI–) group. In the TVI+ group, the prevalence of significant TR decreased from 52% to about 20% in the first 6 months after implantation (P \u3c .01). Overall survival and HF readmission–free survival were comparable between the TVI+ and TVI– patients. In contrast, patients in both groups who had significant postoperative TR during early follow-up had worse 2-year HF readmission–free survival (36% in patients with significant postoperative TR vs 55% in those without significant postoperative TR; P = .028). Conclusions: Concomitant TVI with LVAD implantation improved TR in most patients but did not have an impact on clinical outcomes. Significant postoperative TR after LVAD implantation, in patients with and without TVI, was associated with worse HF-free outcomes