Macroscopic deposition of epicardial adipose tissue (EAT) has been strongly associated with numerous indices of obesity and cardiovascular disease risk. In contrast, the morphology of EAT adipocytes has rarely been investigated. We aimed to determine whether obesity-driven adipocyte hypertrophy, which is characteristic of other visceral fat depots, is found within EAT adipocytes. EAT samples were collected from cardiac surgery patients (n = 49), stained with haematoxylin & eosin, and analysed for mean adipocyte size and non-adipocyte area. EAT thickness was measured using echocardiography. A significant positive relationship was found between EAT thickness and body mass index (BMI). When stratified into standardized BMI categories, EAT thickness was 58.7% greater (p = 0.003) in patients from the obese (7.3 ± 1.8 mm) compared to normal (4.6 ± 0.9 mm) category. BMI as a continuous variable significantly correlated with EAT thickness (r = 0.56, p < 0.0001). Conversely, no correlation was observed between adipocyte size and either BMI or EAT thickness. No difference in the nonadipocyte area was found between BMI groups. Our results suggest that the increased macroscopic EAT deposition associated with obesity is not caused by adipocyte hypertrophy. Rather, alternative remodelling via adipocyte proliferation might be responsible for the observed EAT expansion. ARTICLE HISTORY

Primary angiosarcoma of pulmonary artery is a very rare lesion. We present a case of primary angiosarcoma that was initially misdiagnosed as a subacute massive pulmonary thromboembolism in a 30-year-old man. This rare disease is usually indistinguishable from acute or chronic thromboembolic disease of the pulmonary arteries. The clinical and radiological findings of pulmonary artery angiosarcoma are similar to those of pulmonary thromboembolism. Although the incidence of pulmonary artery angiosarcoma is very low, our case demonstrates that this disease entity should be included in the differential diagnosis of pulmonary thromboembolism. Patients with early identification can have curative potential with aggressive surgical intervention.

Primary spontaneous pneumothorax is a common problem faced by doctors in medical practice. It is a significant global health problem affecting adolescent and young adults. This article will review the etiopathology, diagnosis and current management guidelines. It aims to improve clinical practice and compliance to the complexities of procedures involved in management.

The release of Ca2+ by ryanodine receptor (RyR2) channels is critical for cardiac function. However, abnormal RyR2 activity has been linked to the development of arrhythmias, including increased spontaneous Ca2+ release in human atrial fibrillation (AF). Clustering properties of RyR2 have been suggested to alter the activity of the channel, with remodeling of RyR2 clusters identified in pre-clinical models of AF and heart failure. Whether such remodeling occurs in human cardiac disease remains unclear. This study aimed to investigate the nanoscale organization of RyR2 clusters in AF patients – the first known study to examine this potential remodeling in diseased human cardiomyocytes. Right atrial appendage from cardiac surgery patients with paroxysmal or persistent AF, or without AF (non-AF) were examined using super-resolution (dSTORM) imaging. Significant atrial dilation and cardiomyocyte hypertrophy was observed in persistent AF patients compared to non-AF, with these two parameters significantly correlated. Interestingly, the clustering properties of RyR2 were remarkably unaltered in the AF patients. No significant differences were identified in cluster size (mean ∼18 RyR2 channels), density or channel packing within clusters between patient groups. The spatial organization of clusters throughout the cardiomyocyte was also unchanged across the groups. RyR2 clustering properties did not significantly correlate with patient characteristics. In this first study to examine nanoscale RyR2 organization in human cardiac disease, these findings indicate that RyR2 cluster remodeling is not an underlying mechanism contributing to altered channel function and subsequent arrhythmogenesis in human AF.

Torsion of lobes of the lung is a rare complication following lung transplantation. We present a case of counterclockwise torsion of the right lung allograft and review of nine additional cases in the literature of lobar torsion following lung transplantation. A high degree of suspicion is needed for early diagnosis with rapid surgical intervention to preserve lung viability.