Publications by authors named "Georgi Petrov"

The hyper-Raman scattering (HRS) spectra of biologically significant molecules (D-glucose, L-alanine, L-arabinose, L-tartaric acid) in aqueous solutions are reported. The HRS spectra were measured using a picosecond laser at 532 nm operating at a MHz repetition rate. High signal to noise spectra were collected with a commercial spectrometer and CCD without resonant, nanoparticle, or surface enhancement.

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Introduction: Sex differences in the adaptation to pressure overload have been described in humans, as well as animal models, and have been related to sex-specific expression of mitochondrial genes. We therefore tested whether sex differences in cardiac mitochondrial respiration exist in humans with aortic stenosis (AS). We also examined whether these potential differences may be at least partially due to sex hormones by testing if mitochondrial respiration is affected by estrogen (17ß-estradiol (E2)).

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Background: In 2009, updated European Society of Cardiology guidelines on the prevention, diagnosis, and treatment of infective endocarditis (IE) were released and restricted the use of antibiotic prophylaxis to high-risk patients only. The aim of this study was to analyze the effect of the restrictive antibiotic regimen on the incidence and manifestations of surgically treated IE before and after the guideline change.

Methods: This study retrospectively analyzed data of 4917 patients who underwent valve surgical procedures for IE between 1994 and 2018 in 6 German cardiac surgery centers.

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Hydrogen bonding plays an essential role in biological processes by stabilizing proteins and lipid structures as well as controlling the speed of enzyme catalyzed reactions. Dimethyl sulfoxide-water (DMSO-HO) solution serves as a classical model system by which the direct and indirect effects of hydrogen bonding between water hydrogens and the sulfoxide functional group can be explored. The complex transition from self-bonding to heterogeneous bonding is important, and multiple spectroscopic approaches are needed to provide a detailed assessment of those interactions.

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Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) may be cannulated using either central (cannulation of aorta) or peripheral (cannulation of femoral or axillary artery) access. The ideal cannulation approach for postcardiotomy cardiogenic shock (PCS) is still unknown. The aim of this study is to compare the outcome of patients with PCS who were supported with central vs.

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Background: It is current practice to perform concomitant coronary artery bypass grafting (CABG) in patients with infective endocarditis (IE) who have relevant coronary artery disease (CAD). However, CABG may add complexity to the operation. We aimed to investigate the impact of concomitant CABG on perioperative outcomes in patients undergoing surgery for IE.

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Background: Rivaroxaban, a direct oral factor Xa inhibitor, mediates anti-inflammatory and cardiovascular-protective effects besides its well-established anticoagulant properties; however, these remain poorly characterized. Extracellular vesicles (EVs) are important circulating messengers regulating a myriad of biological and pathological processes and may be highly relevant to the pathophysiology of atrial fibrillation as they reflect alterations in platelet and endothelial biology. However, the effects of rivaroxaban on circulating pro-inflammatory EVs remain unknown.

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Background:  With this study we aimed to analyze if the separate consideration of body mass index (BMI) could provide any superior predictive values compared with the established risk scores in isolated minimally invasive mitral valve surgery (MIMVS). This might facilitate future therapeutic decision-making, e.g.

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Chemical imaging of calcifications was demonstrated in the depth of a tissue. Using long wavelength excitation, broadband coherent anti-Stokes Raman scattering and hierarchical cluster analysis, imaging and chemical analysis were performed 2 mm below the skin level in a model system. Applications to breast cancer diagnostics and imaging are discussed together with the methods to further extend the depth and improve the spatial resolution of chemical imaging.

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The aim of this study was to evaluate the prognostic value of osteopontin (OPN) as a marker for left ventricular (LV) hypertrophy and its reversibility after surgical aortic valve replacement (SAVR). Echocardiographic data and OPN plasma levels of 149 consecutive patients undergoing SAVR were obtained preoperatively and 3 months postoperatively. OPN was measured by Quantikine Human OPN immunoassay.

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Background: Delirium is a common complication after cardiac surgery that leads to increased costs and worse outcomes. This retrospective study evaluated the potential risk factors and postoperative impact of delirium on cardiac surgery patients.

Methods: One thousand two hundred six patients who underwent open-heart surgery within a single year were included.

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Objectives: Prosthetic valve endocarditis is associated with worse outcomes compared with native valve endocarditis. Our aim was to evaluate the impact of native valve endocarditis versus prosthetic valve endocarditis on postoperative outcomes and long-term survival and to identify preoperative risk factors in a large cohort of 4300 patients with infective endocarditis.

Methods: This retrospective cohort study was conducted in 5 German Cardiac Surgery Centers: the Clinical Multicenter Project of Analysis of Infective Endocarditis in Germany.

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We present a narrowband laser system tunable from 219 to 236 nm for deep ultraviolet (DUV) Raman spectroscopy. The demonstrated laser system produces 6.7 ps nearly transform-limited pulses with energy up to 0.

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Objectives: Mitral valve repair is the preferred method used to address mitral valve regurgitation, whereas transcatheter mitral valve repair is recommended for high-risk patients. We evaluated the risk-predictive value of the age-adjusted Charlson comorbidity index (aa-CCI) in the setting of minimally invasive mitral valve surgery.

Methods: The perioperative course and 1-year follow-up of 537 patients who underwent isolated or combined minimally invasive mitral valve surgery were evaluated for 1-year mortality as the primary end point and other adverse events.

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Objectives: Despite substantial scientific effort, the relationship between stroke after coronary artery bypass grafting and the use of the aortic no-touch off-pump technique (anOPCAB) remains incompletely understood. The present study aimed to define the effect of anOPCAB on the occurrence and time point of stroke.

Methods: A total cohort of 15,042 consecutive patients underwent surgical myocardial revascularization at a single institution.

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We aimed to investigate the prevalence of gastrointestinal bleeding (GIB) events in patients supported with HeartWare ventricular assist device (VAD) and activated lavare cycle. Thirty-two GIB events were documented in 22 patients (21%) after median support duration of 22 days (IQR: 11-157 days). There were 13 patients with early episodes of GIB.

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We introduce a unique technique for generating directional coherent emissions that could be utilized to create coherent sources in a wide range of frequencies from the extreme ultraviolet (XUV) to the deep infrared. This is accomplished without population inversion by pumping a two-level system with a far-detuned strong optical field that induces the splitting of the two-level system. A nonlinear process of four-wave mixing then occurs across the split system, driving coherent emission at sidebands both red- and blue-detuned from the pump frequency, and propagates both forward and backward along the pump beam path.

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Tunable narrow-band short-pulse coherent emission can be generated by the optical parametric amplification of a seeded continuous wave (CW) laser. However, the residual CW pedestal can affect the accuracy of the optical measurements and the exact interpretation of the experimental data. We demonstrate a simple approach to removing the residual CW seed in a frequency tunable, seeded parametric amplification setup in the nanosecond regime by adding an additional parametric amplification stage which is seeded by an idler wave from the first stage.

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De novo aortic valve insufficiency (AI) is a frequent occurrence in patients supported with left ventricular assist device (LVAD). The European version of the HeartWare LVAD has intermittent low-speed software (lavare cycle) to facilitate intermittent aortic valve opening. We examined aortic valve opening status and prevalence of AI in patients supported with HeartWare LVAD and activated lavare cycle.

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Objectives: Selected patients who failed to be weaned off temporary veno-arterial extracorporeal membrane oxygenation (VA-ECMO) support may be considered for long-term left ventricular assist devices (LVADs). Activation of the systemic inflammatory response due to the cardiopulmonary bypass (CPB) machine and its associated deleterious effects on the coagulation system have been well documented. The aim of the study was to compare the outcome of patients receiving VAD on VA-ECMO with patients who were converted to CPB at the time of VAD implantation.

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Fast and sensitive Raman spectroscopy measurements are imperative for a large number of applications in biomedical imaging, remote sensing and material characterization. Stimulated Raman spectroscopy offers a substantial improvement in the signal-to-noise ratio but is often limited to a discrete number of wavelengths. In this report, by introducing an electronically-tunable acousto-optical filter as a wavelength selector, a novel approach to a broadband stimulated Raman spectroscopy is demonstrated.

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Fast and sensitive Raman spectroscopy measurements are imperative for a large number of applications in biomedical imaging, remote sensing and material characterization. In this report, by introducing an electronically-tunable acousto-optical filter as a wavelength selector, we demonstrated a novel instrumentation to the broadband coherent Raman spectroscopy. System's tunability allows assessing Raman transitions ranging from <400 cm(-1) to 4500 cm(-1).

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Raman spectroscopy is an important tool in understanding chemical components of various materials. However, the excessive weight and energy consumption of a conventional CCD-based Raman spectrometer forbids its applications under extreme conditions, including unmanned aircraft vehicles (UAVs) and Mars/Moon rovers. In this article, we present a highly sensitive, shot-noise-limited, and ruggedized Raman signal acquisition using a time-correlated photon-counting system.

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A novel concept of Brillouin imaging and sensing via time-resolved optical (BISTRO) measurements is introduced for flow cytometry applications. The system affords robust, maintenance-free and high-speed elasticity-sensitive measurements.

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