Erythrocyte aggregation in sudden flow arrest is linked to hyperthermia, hypoxemia, and band 3 availability.

BACKGROUND: Erythrocyte aggregation is a phenomenon that is commonly found in several pathological disease states: stroke, myocardial infarction, thermal burn injury, and COVID-19. Erythrocyte aggregation is characterized by rouleaux, closely packed stacks of cells, forming three-dimensional structures. Healthy blood flow monodisperses the red blood cells (RBCs) throughout the vasculature; however, in select pathological conditions, involving hyperthermia and hypoxemia, rouleaux formation remains and results in occlusion of microvessels with decreased perfusion. OBJECTIVES: Our objective is to address the kinetics of rouleaux formation with sudden cessation of flow in variable temperature and oxygen conditions. METHODS: RBCs used in this in vitro system were obtained from healthy human donors. Using a vertical stop-flow system aligned with a microscope, images were acquired and analyzed for increased variation in grayscale to indicate increased aggregation. The onset of aggregation after sudden cessation of flow was determined at proscribed temperatures (37-49°C) and oxygen (0%, 10%), and in the presence and absence of 4, 4'-Diisothiocyano-2,2'-stilbenedisulfonic acid (DIDS). Both autologous and homologous plasma were tested. RESULTS: RBCs in autologous plasma aggregate faster and with a higher magnitude with both hyperthermia and hypoxemia. Preventing deoxyhemoglobin from binding to band 3 with DIDS (dissociates the cytoskeleton from the membrane) fully blocks aggregation. Further, RBC aggregation magnitude is greater in autologous plasma. CONCLUSIONS: We show that the C-terminal domain of band 3 plays a pivotal role in RBC aggregation. Further, aggregation is enhanced by hyperthermia and hypoxemia.

Balloon Aortic Valvuloplasty With Same-Setting Complex Percutaneous Coronary Intervention in the TAVR Era: A Case Series.

BACKGROUND: The use of balloon aortic valvuloplasty (BAV) prior to same-setting complex percutaneous coronary intervention (PCI) in patients with severe aortic stenosis (AS) and concomitant severe coronary artery disease (CAD) has not been well studied in the era of transcatheter aortic valve replacement (TAVR). METHODS: We reviewed 379 BAVs performed between January 2016 and April 2020 at an academic tertiary-care medical center. Overall, 327 BAVs were performed in the setting of TAVR. Of the remaining 52 BAVs, 20 were performed immediately prior to same-setting complex PCI. We examined the baseline and procedural data, and clinical outcomes of these cases. RESULTS: Mean patient age was 81 ± 9 years and 70% were men. Chronic kidney disease (40%), diabetes mellitus (35%), and atrial fibrillation (35%) were the most prevalent comorbidities. Rotational atherectomy was performed in 75% of cases and Impella device was utilized in 15%. PCI of distal left main coronary artery and proximal left anterior descending coronary artery was performed in 30% and 80% of cases, respectively. Mean contrast volume was 149 ± 61 mL, fluoroscopy time was 37 ± 20 minutes, total skin dose was 2821 ± 1931 mGy, and total area dose was 18651 ± 12090 µGy/m². Rate of in-hospital complications was low, with a 0% mortality and stroke rate. Eighty percent of patients were referred for TAVR; 70% went on to undergo successful TAVR and 10% deferred TAVR due to improvement in symptoms. CONCLUSIONS: BAV with same-setting complex PCI is safe and feasible in patients with severe AS and severe CAD awaiting TAVR.