Strong π-stacking causes unusually large anisotropic thermal expansion and thermochromism.

π-stacking in ground-state dimers/trimers/tetramers of N-butoxyphenyl(naphthalene)diimide (BNDI) exceeds 50 kcal ⋅ mol-1 in strength, drastically surpassing that for the *3[pyrene]2 excimer (∼30 kcal ⋅ mol-1; formal bond order = 1) and similar to other weak-to-moderate classical covalent bonds. Cooperative π-stacking in triclinic (BNDI-T) and monoclinic (BNDI-M) polymorphs effects unusually large linear thermal expansion coefficients (α a , α b , α c , ß) of (452, -16.8, -154, 273) × 10-6 ⋅ K-1 and (70.1, -44.7, 163, 177) × 10-6 ⋅ K-1, respectively. BNDI-T exhibits highly reversible thermochromism over a 300-K range, manifest by color changes from orange (ambient temperature) toward red (cryogenic temperatures) or yellow (375 K), with repeated thermal cycling sustained for over at least 2 y.

Platypnea-Orthodeoxia in Patients on Hemodialysis: A New Approach to Its Pathophysiology and Implications for Treatment.

Platypnea-orthodeoxia is a poorly understood clinical syndrome resulting in dyspnea and hypoxemia in the upright position, which diminishes with recumbency. Recognition of the disease is limited by its low prevalence and decreased awareness among clinicians. However, understanding the disease, its pathophysiology, its clinical presentation, and the possible therapeutic options is vital in the management of these patients. Here, we present 2 cases of platypnea- orthodeoxia where oxygen saturations worsened with hemodialysis. After highlighting the common features in the clinical pattern of each patient, we present a pressure-mediated pathophysiologic mechanism (in contrast to a previously reported morphologically based hypothesis) to explain the characteristic effects of hemodialysis on hypoxia in platypnea-orthodeoxia. We present a novel diagnostic approach using balloon occlusion testing when the diagnosis is unclear and illustrate how treatments can be tailored to the comorbidities of a specific patient.

Incidence and characteristics of patients presenting with acute myocardial infarction and non-obstructive coronary artery disease.

OBJECTIVES: This study aimed to characterize the etiologies of patients presenting with myocardial infarction (MI) and found to have non-obstructive coronary artery disease (NOCAD) and compare risk factors and in-hospital mortality to those with obstructive coronary artery disease (CAD). BACKGROUND: Patients presenting with an MI are often found to have NOCAD defined as less than 50% luminal diameter reduction by visual estimation on coronary angiography. METHODS: This study is a retrospective analysis of a total of 2,038 patients that presented to NorthShore University HealthSystem with MI and underwent coronary angiography from 2010 to 2013. RESULTS: 1,822 patients (89%) had CAD and 216 (11%) had NOCAD. Of the NOCAD patients, the most common etiologies were Takotsubo cardiomyopathy (28%), no alternative explanation (26%), demand ischemia (21%), myopericarditis (7%), coronary artery vasospasm (5%), and coronary artery dissection (3%). NOCAD patients were more likely to be younger and female. There was no significant difference between NOCAD and CAD patients in terms of in-hospital mortality (3.7% vs. 4.0% respectively, OR = 1.1, 95% CI 0.5-2.3, P = 0.83 by univariate logistic regression, OR = 1.2, 95% CI 0.5-3.1, P = 0.74 by multivariable analysis). CONCLUSIONS: CAD patients were more likely to have traditional risk factors of diabetes, hypertension, hypercholesterolemia, previous MI, previous revascularization with percutaneous coronary intervention or coronary artery bypass graft surgery. Patients presenting with MI and NOCAD were found to have several different etiologies on coronary angiography with the most common being Takotsubo cardiomyopathy.

Spontaneous right-sided microcavitations in a healthy adult.

UNLABELLED: Spontaneous echo contrast (SEC) is frequently observed in patients with structural and functional cardiovascular abnormalities. Literature describes cases of SEC either from agglutination of red blood cells and plasma proteins or from microcavitations. SEC secondary to the former is an independent predictor of future thromboembolic events and is most commonly observed in the left atrium or left atrial appendage. Thus, many authors reason that left atrial SEC is an indication for initiating anticoagulant therapy. We report a rare case of right atrial SEC that was incidentally found during echocardiographic evaluation of isolated peripheral edema in a healthy adult with a structurally normal heart. At present, there are no studies to offer guidance for management of right atrial SEC. This case emphasizes a necessary area of future research. LEARNING POINTS: Cardiovascular implications of SEC.Diagnostic evaluation and management of SEC.