ABSTRACT
INTRODUCTION: The evaluation of myocardial contractility is essential in cardiology practice. The gold standard for this evaluation is the end-systolic elastance, but it the method involved is complex. Echocardiographic measurement of the ejection fraction (EF) is the most commonly used parameter in clinical practice, but it has significant limitations, especially in patients with afterload mismatch. In this study, the area under the curve (AUC) of the isovolumetric contraction was measured to evaluate the myocardial contractility in patients with pulmonary arterial hypertension and severe aortic stenosis. METHODS: 110 patients with severe aortic stenosis and pulmonary arterial hypertension were included in this study. The AUC of the isovolumetric contraction was measured using pressure curves of the right ventricle-pulmonary artery and left ventricle-aorta ascendens. This AUC was then correlated with the echocardiographically measured EF, stroke volume (SV), and total ventricular work. RESULTS: The AUC of the isovolumetric contraction showed a statistically significant correlation with the EF of the corresponding ventricle (p < 0.0001). Both the AUC of the isovolumetric contraction and the EF showed a statistically significant correlation with the total work of the ventricle (AUC: R2 0.49, p < 0.001; EF: R2 0.51, p < 0.001). However, the SV only showed a statistically significant correlation with the EF. A statistically significant one-sample t-test could be found for the EF (decreased, p < 0.001) and for the AUC of the isovolumetric contraction (increased, p < 0.001), but not for the total work of the ventricle. CONCLUSION: The AUC space of the isovolumetric contraction is a useful marker of ventricular performance in patients with afterload mismatch, showing a statistically significant correlation with the EF and the total ventricular work. This method may have potential for use in clinical practice, especially in challenging cardiological cases. However, further studies are needed to evaluate its usefulness in healthy individuals and in other clinical scenarios.
ABSTRACT
S. aureus is a pathogenic bacterium that causesinfections. Its virulence is due to surface components, proteins, virulence genes, SCCmec, pvl, agr, and SEs, which are low molecular weight superantigens. SEs are usually encoded by mobile genetic elements, and horizontal gene transfer accounts for their widespread presence in S. aureus. This study analyzed the prevalence of MRSA and MSSA strains of S. aureus in two hospitals in Greece between 2020-2022 and their susceptibility to antibiotics. Specimens collected were tested using the VITEK 2 system and the PCR technique to detect SCCmec types, agr types, pvl genes, and sem and seg genes. Antibiotics from various classes were also tested. This study examined the prevalence and resistance of S. aureus strains in hospitals. It found a high prevalence of MRSA and that the MRSA strains were more resistant to antibiotics. The study also identified the genotypes of the S. aureus isolates and the associated antibiotic resistances. This highlights the need for continued surveillance and effective strategies to combat the spread of MRSA in hospitals. This study examined the prevalence of the pvl gene and its co-occurrence with other genes in S. aureus strains, as well as their antibiotic susceptibility. The results showed that 19.15% of the isolates were pvl-positive and 80.85% were pvl-negative. The pvl gene co-existed with other genes, such as the agr and enterotoxin genes. The results could inform treatment strategies for S. aureus infections.
