Degenerative mitral valve stenosis: Diagnosis and management.

Mitral stenosis (MS) is a common valvular disease characterized by narrowing of the mitral valve orifice and a reduction in mitral valve area (MVA). While rheumatic MS (RMS) is frequently encountered in young individuals in developing countries, degenerative MS (DMS) is seen in the elderly in developed countries and its prevalence is increasing. DMS is usually a late presentation of mitral annular calcification (MAC). Accurate assessment of MVA in patients with MAC is challenging due to the alterations in the atrial and valvular structures as well as the presence of other comorbidities in this aging population. We will review the epidemiology, etiology, pathophysiology, diagnostic assessment, and management of DMS and compare the findings with RMS. The latest therapeutic approaches, including medical, surgical, and transcatheter valvular interventions, will be discussed.

Pneumopericardium Leading to Cardiac Tamponade in a Patient with Lung Cancer.

Pneumopericardium resulting in cardiac tamponade in patients with lung cancer is not documented. We report a case of squamous cell carcinoma of the lung complicated by pneumopericardium and subsequent cardiac tamponade. The patient underwent an urgent pericardial window with rapid improvement in symptoms. We discuss the possible pathogenesis and treatment options for this rare condition.

Substrate modulation of fatty acid effects on energization and respiration of kidney proximal tubules during hypoxia/reoxygenation.

Kidney proximal tubules subjected to hypoxia/reoxygenation develop a nonesterified fatty acid-induced energetic deficit characterized by persistent partial mitochondrial deenergization that can be prevented and reversed by citric acid cycle substrates. To further assess the role of competition between fatty acids and substrates on inner membrane substrate carriers in the deenergization and the contribution to deenergization of fatty acid effects on respiratory function, digitonin-permeabilized rabbit and mouse tubules were studied using either addition of exogenous oleate after control normoxic incubation or increases of endogenous fatty acids produced by hypoxia/reoxygenation. The results demonstrated major effects of matrix oxaloacetate accumulation on succinate-supported energization and respiration and their modification by fatty acids. Improvements of energization in the presence of fatty acids by glutamate were shown to result predominantly from lowering matrix oxaloacetate rather than from amelioration of transmembrane cycling of fatty acids and uncoupling. Mouse tubules had 2.5 fold higher rates of succinate utilization, which resulted in stronger effects of oxaloacetate accumulation than rabbit tubules. Hypoxia/reoxygenation induced respiratory inhibition that was more severe for complex I-dependent substrates. Fatty acids themselves did not acutely contribute to this respiratory inhibition, but lowering them during 60 min. reoxygenation to allow recovery of ATP during that period alleviated it. These data clarify the basis for the nonesterified fatty acid-induced mitochondrial energetic deficit in kidney proximal tubules that impairs structural and functional recovery and provide insight into interactions that need to be considered in the design of substrate-based interventions to improve mitochondrial function.