Recurrent Syncope Associated with Lung Cancer

Investigation of air bubble behaviour after gas embolism events induced in a microfluidic network mimicking microvasculature

Gas embolism is a medical condition that occurs when gas bubbles are present in veins or arteries, decreasing blood flow and potentially reducing oxygen delivery to vital organs, such as the brain. Although usually reported as rare, gas embolism can lead to severe neurological damage or death. However, presently, only limited understanding exists regarding the microscale processes leading to the formation, persistence, movement, and resolution of gas emboli, as modulated by microvasculature geometrical features and blood properties. Because gas embolism is initially a physico-chemical-only process, with biological responses starting later, the opportunity exists to fully study the genesis and evolution of gas emboli using in vitro microfluidic networks mimicking small regions of microvasculature. The microfluidics networks used in this study, which aim to mimic microvasculature geometry, comprise linear channels with T-, or Y-junction air inlets, with 20, 40, and 60 μm widths (arterial or venous), and a 30 μm width honeycombed network (arterial) with three bifurcation angles (30°, 60°, and 90°). Synthetic blood, equivalent to 46% haematocrit concentrations, and water were used to study the modulation of gas embolism-like events by liquid viscosity. Our study shows that (i) longer bubbles with lower velocity occur in narrower channels, e.g., with 20 μm width; (ii) the resistance of air bubbles to the flow increases with the higher haematocrit concentration; and lastly (iii) the propensity of gas embolism-like events in honeycomb architectures increases for more acute, e.g., 30°, bifurcation angles. A dimensionless analysis using Euler, Weber, and capillary numbers demarcated the conditions conducive to gas embolism. This work suggests that in vitro experimentation using microfluidic devices with microvascular tissue-like structures could assist medical guidelines and management in preventing and mitigating the effects of gas embolism.

Direct Endoscopic Necrosectomy: Timing and Technique

Walled-off pancreatic necrosis (WOPN) is one of the local complications of acute pancreatitis (AP). Several interventional techniques have been developed over the last few years. The purpose of this narrative review is to explore such methodologies, with specific focus on endoscopic drainage and direct endoscopic necrosectomy (DEN), through evaluation of their indications and timing for intervention. Findings indicated how, after the introduction of lumen-apposing metal stents (LAMS), DEN is becoming the favorite technique to treat WOPN, especially when large solid debris or infection are present. Additionally, DEN is associated with a lower adverse events rate and hospital stay, and with improved clinical outcome.

Heart of the Matter: Syncope as a Rare Presentation of Lung Cancer Invading the Heart

Syncope is common, affecting approximately 1 million Americans every year. Although multiple pathophysiological mechanisms regarding its etiology have been documented, neurocardiogenic or vasovagal syncope is the most common cause of these episodes. Other less appreciated etiologies include various cardiac abnormalities in which a structural, electrical, or obstructive disturbance leads to a temporary reduction in blood flow to the brain, resulting in transient loss of consciousness. Cardiac malignancies, while rare, can present with syncope by either disrupting the cardiac conduction apparatus or simply obstructing blood flow through the cardiac chambers. Electrocardiograms and echocardiography are often very helpful in identifying these abnormalities. Here, we report a rare case of late-stage invasive squamous cell carcinoma of the lung presenting with recurrent syncopal events. The cancer invaded the cardiac right atrium causing various dysrhythmias, leading to a very rare cause of cardiogenic syncope. We also discuss how lung cancer can present in a subclinical manner and at times without obvious respiratory symptoms, dramatic physical examination abnormalities, and/or thoracic imaging abnormalities on chest radiograph.

Small-cell lung cancer with recurrent syncope as the initial symptom: A case report and literature review

Small-cell lung cancer (SCLC) presenting with syncope as the initial symptom is rare in adults. This onset of tumour-induced syncope cannot be screened or differentiated by coronary angiography, magnetic resonance angiography of the neck or 24-hour dynamic electrocardiogram. We herein describe the case of a 61-year-old man who presented with recurrent syncope that resolved after the first course of chemotherapy (carboplatin plus etoposide) for SCLC. A mass measuring 57×53 mm was identified in the left hilum, and a diagnosis of limited-disease SCLC (T4N2M0, IIIB) was made. Considering the rapid and complete remission after the treatment of the primary lesion, we hypothesised that the syncope was neurogenic and associated with cancer. Thus, 8 similar cases retrieved from PubMed were reviewed and, for the first time, the mechanism underlying the syncope was identified, which may involve tumour location, neurobiology and other inducing factors. Thus, for the treatment of such SCLC patients, standard chemotherapy is crucial for preventing syncopal attacks.