Arch vessel injury: geometrical considerations. Implications for the mechanism of traumatic myocardial infarction II

Internal Mammary Artery Injury without Chest Wall Fractures after Cardiopulmonary Resuscitation: A Case Report

High-quality cardiopulmonary resuscitation (CPR) is crucial for survival from cardiac arrest. However, various chest compression-associated injuries have been reported. Internal mammary artery (IMA) injury is one of the rare complications after CPR, and most of cases include rib and sternum fractures. In this report, we describe a rare case of IMA injury without chest wall fractures after CPR. An 85-year-old man with a history of acute myocardial infarction 2 weeks prior visited to our hospital for sustained ventricular tachycardia (VT). After admission, sustained VT requiring CPR occurred several times. Emergency coronary angiogram revealed 90% stenosis at the left anterior descending artery. Hence, emergency percutaneous coronary intervention (PCI) was performed. During the PCI, blood gas analysis showed decreasing serum hemoglobin levels. Contrast computed tomography revealed hemothorax and extravasation at the branch of the right IMA without chest wall fractures. The patient's deteriorating hemodynamic condition precluded thoracotomy or embolization to stop the bleeding. The patient died on the next day of hospitalization. IMA injury can occur after CPR, regardless of chest wall fractures and can be fatal without early diagnosis. For an emergency physician, IMA injury should be considered as a cause of unknown anemia after CPR.

The innate immune response to ischemic injury: a multiscale modeling perspective

Background

Cell death as a result of ischemic injury triggers powerful mechanisms regulated by germline-encoded Pattern Recognition Receptors (PRRs) with shared specificity that recognize invading pathogens and endogenous ligands released from dying cells, and as such are essential to human health. Alternatively, dysregulation of these mechanisms contributes to extreme inflammation, deleterious tissue damage and impaired healing in various diseases. The Toll-like receptors (TLRs) are a prototypical family of PRRs that may be powerful anti-inflammatory targets if agents can be designed that antagonize their harmful effects while preserving host defense functions. This requires an understanding of the complex interactions and consequences of targeting the TLR-mediated pathways as well as technologies to analyze and interpret these, which will then allow the simulation of perturbations targeting specific pathway components, predict potential outcomes and identify safe and effective therapeutic targets.

Results

We constructed a multiscale mathematical model that spans the tissue and intracellular scales, and captures the consequences of targeting various regulatory components of injury-induced TLR4 signal transduction on potential pro-inflammatory or pro-healing outcomes. We applied known interactions to simulate how inactivation of specific regulatory nodes affects dynamics in the context of injury and to predict phenotypes of potential therapeutic interventions. We propose rules to link model behavior to qualitative estimates of pro-inflammatory signal activation, macrophage infiltration, production of reactive oxygen species and resolution. We tested the validity of the model by assessing its ability to reproduce published data not used in its construction.

Conclusions

These studies will enable us to form a conceptual framework focusing on TLR4-mediated ischemic repair to assess potential molecular targets that can be utilized therapeutically to improve efficacy and safety in treating ischemic/inflammatory injury.

Circle of Willis atherosclerosis, Alzheimer’s disease and the Dean number

The important role of atherosclerosis in pathophysiology of Alzheimer’s Disease has become evident. Mechanisms such as hyperlipidemia, inflammation, abdominal obesity and insulin resistance are important yet they may not fully explain the specific involvement of the Circle of Willis in these pathologies. The Circle of Wills is a complex geometrical structure which has several areas with different curvature as well as various branching angles of vessels composing the circle. The hemodynamics in this region should take into account the Dean number which indicates the influence of curvature on the resistance to blood flow. Thus, areas with various curvature and angles may have different hemodynamics and there are certain areas in the Circle of Willis that are more likely to develop atherosclerotic changes. Therefore, this could suggest the novel pathophysiological pathway resulting from the geometric peculiarities of the Circle of Willis. One of the directions of future research is to examine whether specific areas of the Circle of Willis are more likely to develop atherosclerotic changes compared to other ones. Selective areas of the Circle of Willis affected by atherosclerotic changes could indicate the primary role of atherosclerosis promoting Alzheimer’s disease although other pathophysiological mechanisms suggesting the opposite direction should be also examined in prospective studies.