Brian D. Hoit

We chose the “natural laboratory” provided by high-altitude native ethnic Tibetan women who had completed childbearing to examine the hypothesis that multiple oxygen delivery traits were associated with lifetime reproductive success and had genomic associations. Four hundred seventeen (417) women aged 46 to 86 y residing at ≥3,500 m in Upper Mustang, Nepal, provided information on reproductive histories, sociocultural factors, physiological measurements, and DNA samples for this observational cohort study. Simultaneously assessing multiple traits identified combinations associated with lifetime reproductive success measured as the number of livebirths. Women with the most livebirths had distinctive hematological and cardiovascular traits. A hemoglobin concentration near the sample mode and a high percent of oxygen saturation of hemoglobin raised arterial oxygen concentration without risking elevated blood viscosity. We propose ongoing stabilizing selection on hemoglobin concentration because extreme values predicted fewer livebirths and directional selection favoring higher oxygen saturation because higher values had more predicted livebirths. EPAS1, an oxygen homeostasis locus with strong signals of positive natural selection and a high frequency of variants occurring only among populations indigenous to the Tibetan Plateau, associated with hemoglobin concentration. High blood flow into the lungs, wide left ventricles, and low hypoxic heart rate responses aided effective convective oxygen transport to tissues. Women with physiologies closer to unstressed, low altitude values had the highest lifetime reproductive success. This example of ethnic Tibetan women residing at high altitudes in Nepal links reproductive fitness with trait combinations increasing oxygen delivery under severe hypoxic stress and demonstrates ongoing natural selection.

Purpose of Review The objective of this manuscript is to examine up-to-date approaches to the diagnosis and treatment of pericardial effusions and cardiac tamponade. Recent Findings Recent recommendations from the American Society of Echocardiography and the European Society of Cardiology have improved our management of the patient with pericardial effusion and cardiac tamponade, but significant knowledge gaps remain. Novel diagnostic and triage strategies have been suggested, and recent information have improved our facility to assess the presence and size of a pericardial effusion, assess its hemodynamic impact, and determine its cause. Summary Despite these recent findings, there is a scarcity of evidence-based data to direct the management of pericardial effusion and cardiac tamponade. While the first-line function of echocardiography in managing these disorders is undisputed, there are increasingly niche functions for multimodality imaging.

Pericarditis is a rare but debilitating complication of cytarabine therapy. While echocardiography can aid with the diagnosis, cardiac MRI has superior accuracy in establishing the diagnosis. In this case, we describe a 65-year-old patient receiving cytarabine as part of induction chemotherapy for acute myeloid leukemia who developed acute pericarditis. Her cardiac MRI revealed pericardial edema on T2-weighted STIR imaging and pericardial late gadolinium enhancement which confirmed the diagnosis.

When pericardial fluid accumulates and exceed the reserve volume of the pericardium or when the pericardium becomes scarred and inelastic, one of three pericardial compressive syndromes may ensue, namely, cardiac tamponade (CT), characterised by the accumulation of pericardial fluid under pressure; constrictive pericarditis (CP), the result of scarring and loss of the normal elasticity of the pericardial sac; and effusive–constrictive pericarditis (ECP), characterised by the concurrence of a tense pericardial effusion and constriction of the heart by the visceral pericardium. Although relatively uncommon, prevalence estimates vary widely and depend on the nature of the cohorts studied, the methods used to diagnose ECP and the manner in which ECP is defined. Most cases of ECP are idiopathic, reflecting the frequency of idiopathic pericardial disease in general, and other causes include radiation, malignancy, chemotherapy, infection and postsurgical/iatrogenic pericardial disease. The diagnosis of ECP often becomes apparent when pericardiocentesis fails to decrease the right atrial pressure by 50% or to a level below 10 mm Hg. Important non-invasive diagnostic modalities include echocardiography, cardiac magnetic resonance and, to a lesser extent, cardiac CT. In cases with clear evidence of pericardial inflammation, a trial of an anti-inflammatory regimen is warranted. A complete pericardiectomy should be reserved for refractory symptoms or clinical evidence of chronic CP.