Thoracic Aortic Aneurysms

Silent Type-B Aortic Dissection Accidentally Discovered in a COVID-19-Positive Patient

Aortic dissection is a critical medical condition that poses a significant threat to life, and if left untreated, it can lead to high mortality and morbidity rates. The risk of various cardiovascular complications, including aortic dissection, is increased in individuals with coronavirus disease 2019 (COVID-19). However, the significance of aortic dissection as a complication in COVID-19 patients is often underestimated. Traditionally, aortic dissection without pain was considered uncommon. However, recent information indicates that symptoms in patients with aortic dissection can be more diverse than previously believed. The classic symptoms of tearing chest, back, or abdominal pain may be absent, making diagnosis challenging. We present the incidental detection of an asymptomatic Stanford type-B aortic dissection during a computed tomography (CT) scan conducted to evaluate COVID-19. The patient was managed through conservative treatment.

Aortic dissection and Covid-19; a comprehensive systematic review

Coronavirus disease 19 (Covid-19) has been declared as a pandemic disease since March 2020; causing wide array of signs and symptoms, many of which result in increased mortality rates worldwide. Although it was initially known as an acute respiratory disease, Covid-19 is accompanied with several extrapulmonary manifestations, of which the cardiovascular ones are of major importance. Among other cardiovascular complications of Covid-19, aortic dissection has been a significant yet underrated problem. The pathophysiology of aortic dissection consists of various inflammatory pathways, that could be influenced by Covid-19 infection. We herein have reviewed articles inclusive of aortic dissection concurrent with Covid-19 infection in a systematic manner, along with the probable similarities in pathophysiology of aortic dissection with Covid-19 infection.

Stem Cell Based Approaches to Modulate the Matrix Milieu in Vascular Disorders

The extracellular matrix (ECM) represents a complex and dynamic framework for cells, characterized by tissue-specific biophysical, mechanical, and biochemical properties. ECM components in vascular tissues provide structural support to vascular cells and modulate their function through interaction with specific cell-surface receptors. ECM–cell interactions, together with neurotransmitters, cytokines, hormones and mechanical forces imposed by blood flow, modulate the structural organization of the vascular wall. Changes in the ECM microenvironment, as in post-injury degradation or remodeling, lead to both altered tissue function and exacerbation of vascular pathologies. Regeneration and repair of the ECM are thus critical toward reinstating vascular homeostasis. The self-renewal and transdifferentiating potential of stem cells (SCs) into other cell lineages represents a potentially useful approach in regenerative medicine, and SC-based approaches hold great promise in the development of novel therapeutics toward ECM repair. Certain adult SCs, including mesenchymal stem cells (MSCs), possess a broader plasticity and differentiation potential, and thus represent a viable option for SC-based therapeutics. However, there are significant challenges to SC therapies including, but not limited to cell processing and scaleup, quality control, phenotypic integrity in a disease milieu in vivo, and inefficient delivery to the site of tissue injury. SC-derived or -inspired strategies as a putative surrogate for conventional cell therapy are thus gaining momentum. In this article, we review current knowledge on the patho-mechanistic roles of ECM components in common vascular disorders and the prospects of developing adult SC based/inspired therapies to modulate the vascular tissue environment and reinstate vessel homeostasis in these disorders.

Surgical aspects of thoracic aortic aneurysms: A case series from a real-world setting

Background

The objective of the present study is to review different surgical features and treatment modalities of thoracic aortic aneurysms.

Methods

This was a retrospective study of 17 patients operated on for thoracic aortic aneurysm in the Department of Cardiovascular Surgery of the Military Hospital of Rabat (Morocco) over a 10-year period, from January 2007 to December 2016. All patients with aneurysms located in the thoracic aorta or extended to the abdominal aorta were included in the study.

Results

The mean age of the patients was 49 ± 6 years. 58% of the patients were symptomatic. 10 patients (62%) had an aneurysm of the ascending thoracic aorta and 2 patients had an aneurysm of the ascending aorta extended to the arch. In 2 patients, the aneurysm was located in the descending thoracic aorta. Three patients (18%) had a post-traumatic false aneurysm of the aortic isthmus. Six patients underwent a Bentall procedure. One patient underwent the Yacoub technique. Two patients underwent ascending aorta replacement using the Wheat technique. In addition, two patients underwent ascending aorta and arch replacement and five patients (29%) underwent descending thoracic aorta replacement. In-hospital mortality was 12%. Two patients (12%) developed paraplegia and two developed renal failure (12%).

Conclusion

Thoracic aortic aneurysms are a serious pathology requiring surgical treatment before complications arise. Replacement of the arch and the descending thoracic aorta still remain a challenge for cardiovascular surgeons because of neurological complications.

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Thoracic aortic aneurysm is a life threatening disease.

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It requires surgical treatment before complications arise.

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Replacement of the arch and the descending thoracic aorta is challenging because of neurological complications.

Upregulation of lincRNA-p21 in thoracic aortic aneurysms is involved in the regulation of proliferation and apoptosis of vascular smooth muscle cells by activating TGF-β1 signaling pathway

OBJECTIVE

Long intergenic noncoding RNA-p21 (lincRNA-p21) has been proved in the pathogenesis of aortic aneurysms, while its functionality in thoracic aortic aneurysms (TAA) and the mechanism of function remains unclear. Therefore our study aimed to investigate the role of lincRNA-p21 in TAA.

METHODS

Aortic media specimens and blood samples were collected from both patients with TAA and healthy controls. Expression of lincRNA-p21 in those tissues was detected by reverse-transcription quantitative polymerase chain reaction (qRT-PCR). Diagnostic values of lincRNA-p21 in aortic media and blood for TAA were evaluated by receiver operating characteristic curve analysis. LincRNA-p21 overexpression human vascular smooth muscle cells (VSMCs) were prepared and the effects of lincRNA-p21 overexpression on cell proliferation and apoptosis were explored by cell counting kit-8 assay and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay, respectively. Expression of lincRNA-p21 and transforming growth factor β1 (TGF-β1) in VSMCs with different treatment was detected by qRT-PCR and Western blot analysis, respectively.

RESULTS

Expression of lincRNA-p21 in aortic media tissues and blood was significantly upregulated in TAA patients than in healthy controls. Expression of lincRNA-p21 in aortic media and blood can be used to effectively distinguish TAA patients form healthy controls. LincRNA-p21 overexpression inhibited proliferation and promoted apoptosis of VSMCs, while TGF-β1 inhibitor reduced those effects. LincRNA-p21 overexpression upregulated TGF-β1 expression, while TGF-β1 activator showed no significant effects on lincRNA-p21 expression in VSMC.

CONCLUSION

LincRNA-p21 participates in TAA by regulating the proliferation and apoptosis of VSMCs through the activation of TGF-β1 signaling pathway.

Epigenetic regulation of TGF-β1 signalling in dilative aortopathy of the thoracic ascending aorta

The term 'epigenetics' refers to heritable, reversible DNA or histone modifications that affect gene expression without modifying the DNA sequence. Epigenetic modulation of gene expression also includes the RNA interference mechanism. Epigenetic regulation of gene expression is fundamental during development and throughout life, also playing a central role in disease progression. The transforming growth factor β1 (TGF-β1) and its downstream effectors are key players in tissue repair and fibrosis, extracellular matrix remodelling, inflammation, cell proliferation and migration. TGF-β1 can also induce cell switch in epithelial-to-mesenchymal transition, leading to myofibroblast transdifferentiation. Cellular pathways triggered by TGF-β1 in thoracic ascending aorta dilatation have relevant roles to play in remodelling of the vascular wall by virtue of their association with monogenic syndromes that implicate an aortic aneurysm, including Loeys-Dietz and Marfan's syndromes. Several studies and reviews have focused on the progression of aneurysms in the abdominal aorta, but research efforts are now increasingly being focused on pathogenic mechanisms of thoracic ascending aorta dilatation. The present review summarizes the most recent findings concerning the epigenetic regulation of effectors of TGF-β1 pathways, triggered by sporadic dilative aortopathy of the thoracic ascending aorta in the presence of a tricuspid or bicuspid aortic valve, a congenital malformation occurring in 0.5-2% of the general population. A more in-depth comprehension of the epigenetic alterations associated with TGF-β1 canonical and non-canonical pathways in dilatation of the ascending aorta could be helpful to clarify its pathogenesis, identify early potential biomarkers of disease, and, possibly, develop preventive and therapeutic strategies.

Advances in the diagnosis of acute aortic syndromes: Role of imaging techniques

Aortic diseases include a wide range of pathological conditions: aortic aneurysms, pseudoaneurysms, acute aortic syndromes, atherosclerotic and inflammatory conditions, genetic diseases and congenital anomalies. Acute aortic syndromes have acute onset and may be life-threatening. They include aortic dissection, intramural haematoma, penetrating aortic ulcer and traumatic aortic injury. Pain is the common denominator to all acute aortic syndromes. Pain occurs regardless of age, gender and other associated clinical conditions. In this review, we deal with the main findings in the clinical setting and the most recent indications for diagnostic imaging, which are aimed to start an appropriate treatment and improve the short- and long-term prognosis of these patients.

The genetics and pathogenesis of thoracic aortic aneurysm disorder and dissections

Major advances have been made over the last 20 years to better elucidate the molecular basis of aortic aneurysmal diseases. Thoracic aortic aneurysm disorder and dissections (TAADs) have a high mortality rate, and one-fifth of TAADs patients have a high familial prevalence of the disease. Clinical presentations of TAADs are different, from no symptom to aortic insufficiency that may result in sudden death. The identification of the genetic factors associated with familial TAADs is beneficial for screening and early intervention of TAADs and provides a paradigm for the study of inherited blood vessel disorders. Defects in multiple genes have been identified as causing TAADs. Many genes/alleles are associated with clinical presentations of TAADs; however, the roles of these gene defects in the pathogenesis of TAADs remain unclear. Genetic studies are now beginning to shed light on the key molecules that regulate the extracellular matrix and cytoskeleton in smooth muscle cells and transforming growth factor-beta signaling pathways involved in TAADs pathogenesis. Deciphering the molecular basis of TAADs will improve our understanding of the basic physiology of aortic function and will provide knowledge of the causative genes/alleles and typical manifestations, which will benefit clinical decision-making going forward.

Clinical utility of a next generation sequencing panel assay for Marfan and Marfan-like syndromes featuring aortopathy

Aortopathy can be defined as aortic dilation, aneurysm, dissection, and tortuosity. Familial aortopathy may occur secondary to fibrillin-1 (FBN1) mutations in the setting of Marfan syndrome, or may occur as a result of other genetic defects with different, but occasionally overlapping, phenotypes. Because of the phenotypic overlap and genetic heterogeneity of disorders featuring aortopathy, we developed a next generation sequencing (NGS) assay and comparative genomic hybridization (CGH) array to detect mutations in 10 genes that cause thoracic aortic aneurysms (TAAs). Here, we report on the clinical and molecular findings in 175 individuals submitted for aortopathy panel testing at ARUP laboratories. Ten genes associated with heritable aortopathies were targeted using hybridization capture prior to sequencing. NGS results were analyzed, and variants were confirmed using Sanger sequencing. Array CGH was used to detect copy-number variation. Of 175 individuals, 18 had a pathogenic mutation and 32 had a variant of uncertain significance (VUS). Most pathogenic mutations (72%) were identified in FBN1. A novel large SMAD3 duplication and FBN1 deletion were identified. Over half who had TAAs or other aortic involvement tested negative for a mutation, suggesting that additional aortopathy genes exist. We anticipate that the clinical sensitivity of at least 10.3% will rise with VUS reclassification and as additional genes are identified and included in the panel. The aortopathy NGS panel aids in the timely molecular diagnosis of individuals with disorders featuring aortopathy and guides proper treatment.

[Age-related morphological changes in the aortic wall in dissecting aneurysm]

OBJECTIVE

To reveal the morphological features of the aorta in its dissection in persons of different age groups.

MATERIAL AND METHODS

The operative material obtained after resection of the aorta for its dissection was examined. The fragments of the wall of the ascending aorta were fixed in 10% formalin solution immediately following its resection. The material was treated by processing and fixing methods; paraffin sections were stained with hemotoxyllin-eosin, orsein by the Van-Gieson, MSB, and Leigh methods.

RESULTS

By analyzing 77 dissecting aortic aneurysm biopsy specimens, the authors presented the structural features of the aortic wall in terms of age-related changes. Examinations were made by light and electron microscopy using special stains. The signs of physiological or premature aging were assessed by elastic skeleton changes. There was a deficiency of collagen and its impaired maturation in all the study cases of vascular aging in the presence of aortic dissection.

CONCLUSION

Quantitative and qualitative changes in the smooth muscle cells were due to both patient age and concomitant hypertension. In young patients, aortic dissection was more frequently caused by a genetically determined disorder in the elastic skeleton in obvious substitutive sclerosis.

A direct comparison of next generation sequencing enrichment methods using an aortopathy gene panel- clinical diagnostics perspective

Background

Aortopathies are a group of disorders characterized by aneurysms, dilation, and tortuosity of the aorta. Because of the phenotypic overlap and genetic heterogeneity of diseases featuring aortopathy, molecular testing is often required for timely and correct diagnosis of affected individuals. In this setting next generation sequencing (NGS) offers several advantages over traditional molecular techniques.

Methods

The purpose of our study was to compare NGS enrichment methods for a clinical assay targeting the nine genes known to be associated with aortopathy. RainDance emulsion PCR and SureSelect RNA-bait hybridization capture enrichment methods were directly compared by enriching DNA from eight samples. Enriched samples were barcoded, pooled, and sequenced on the Illumina HiSeq2000 platform. Depth of coverage, consistency of coverage across samples, and the overlap of variants identified were assessed. This data was also compared to whole-exome sequencing data from ten individuals.

Results

Read depth was greater and less variable among samples that had been enriched using the RNA-bait hybridization capture enrichment method. In addition, samples enriched by hybridization capture had fewer exons with mean coverage less than 10, reducing the need for followup Sanger sequencing. Variants sets produced were 77% concordant, with both techniques yielding similar numbers of discordant variants.

Conclusions

When comparing the design flexibility, performance, and cost of the targeted enrichment methods to whole-exome sequencing, the RNA-bait hybridization capture enrichment gene panel offers the better solution for interrogating the aortopathy genes in a clinical laboratory setting.

Characterization of large genomic deletions in the FBN1 gene using multiplex ligation-dependent probe amplification

BACKGROUND

Connective tissue diseases characterized by aortic aneurysm, such as Marfan syndrome, Loeys-Dietz syndrome and Ehlers Danlos syndrome type IV are heterogeneous and despite overlapping phenotypes, the natural history, clinical manifestations and interventional course for each diagnosis can be quite unique. The majority of mutations involved in the etiology of these disorders are missense and nonsense mutations. However, large deletions and duplications undetected by sequencing may be implicated in their pathogenesis, and may explain the apparent lack of genotype-phenotype correlation in a subset of patients. The objective of this study was to search for large pathogenic deletions and/or duplications in the FBN1, TGFβR1, and TGFβR2 genes using multiplex-ligation dependent probe amplification (MLPA) in patients with aortopathy, in whom no mutations in the FBN1, TGFβR1, and TGFβR2 genes were identified by sequencing.

METHODS

The study included 14 patients from 11 unrelated families with aortic aneurysm. Of those, six patients (including 3 first-degree relatives), fulfilled the revised Ghent criteria for Marfan syndrome, and eight had predominantly aortic aneurysm/dilatation with variable skeletal and craniofacial involvement. MLPA for FBN1, TGFβR1, and TGFβR2 was carried out in all patients. A 385 K chromosome 15 specific array was used in two patients with a deletion of the entire FBN1 in order to define its size and boundaries.

RESULTS

We identified two novel large deletions in the FBN1 gene in four patients of two unrelated families who met clinical diagnostic criteria for Marfan syndrome. One patient was found to have a FBN1 deletion encompassing exons 1-5. The other three patients had a 542 Kb deletion spanning the whole FBN1 gene and five additional genes (SLC24A5, MYEF2, CTXN2, SLC12A1, DUT) in the chromosome 15.

CONCLUSIONS

Our findings expand the number of large FBN1 deletions, and emphasize the importance of screening for large genomic deletions in connective tissue disorders featuring aortopathies, especially for those with classic Marfan phenotype.

Endovascular interventions for descending thoracic aortic aneurysms: The pivotal role of the clinical nurse in postoperative care

Descending thoracic aortic aneurysms (dTAA) comprise 40% of all aneurysms arising from the thoracic aorta. Because rupture of thoracic aneurysms is associated with a 94% mortality rate, timely detection, surveillance and treatment is imperative. Endovascular stent-graft repair of thoracic aneurysms was first performed in 1992 and has become an accepted treatment option for this condition in select candidates. There is an abundance of information for the care of patients after open surgical repair of dTAA. However, still relatively few written guidelines exist in the nursing literature for postoperative care and complications associated with endovascular stent-graft repair. The prevalence of aortic endografting, however, now makes it necessary for nurses to have a solid knowledge base in the operative procedure, complications and postoperative care for this patient population. Ideal candidates for aortic endografting undergo CTA or MRI preoperatively and fit a set of strict anatomic criteria to ensure proper delivery and fixation of the device. The early postoperative care focuses on minimizing pulmonary complications, paraplegia, renal failure and embolic complications such as stroke and limb ischemia through skilled nursing assessment and interventions. Late complications such as stent-graft migration, kinking, stent fracture and endoleak are often without symptoms, making it necessary for patients to be educated about these potential complications and to be encouraged to comply with lifelong follow up. This overview provides a sound cognitive framework for nurses practicing in a vascular surgery milieu.

Epigenetic control of vascular smooth muscle cells in Marfan and non-Marfan thoracic aortic aneurysms

Aims

Human thoracic aortic aneurysms (TAAs) are characterized by extracellular matrix breakdown associated with progressive smooth muscle cell (SMC) rarefaction. These features are present in all types of TAA: monogenic forms [mainly Marfan syndrome (MFS)], forms associated with bicuspid aortic valve (BAV), and degenerative forms. Initially described in a mouse model of MFS, the transforming growth factor-β1 (TGF-β1)/Smad2 signalling pathway is now assumed to play a role in TAA of various aetiologies. However, the relation between the aetiological diversity and the common cell phenotype with respect to TGF-β signalling remains unexplained.

Methods and results

This study was performed on human aortic samples, including TAA [MFS, n = 14; BAV, n = 15; and degenerative, n = 19] and normal aortas (n = 10) from which tissue extracts and human SMCs and fibroblasts were obtained. We show that all types of TAA share a complex dysregulation of Smad2 signalling, independent of TGF-β1 in TAA-derived SMCs (pharmacological study, qPCR). The Smad2 dysregulation is characterized by an SMC-specific, heritable activation and overexpression of Smad2, compared with normal aortas. The cell specificity and heritability of this overexpression strongly suggest the implication of epigenetic control of Smad2 expression. By chromatin immunoprecipitation, we demonstrate that the increases in H3K9/14 acetylation and H3K4 methylation are involved in Smad2 overexpression in TAA, in a cell-specific and transcription start site-specific manner.

Conclusion

Our results demonstrate the heritability, the cell specificity, and the independence with regard to TGF-β1 and genetic backgrounds of the Smad2 dysregulation in human thoracic aneurysms and the involvement of epigenetic mechanisms regulating histone marks in this process.

Syndromic and non-syndromic aneurysms of the human ascending aorta share activation of the Smad2 pathway

Common features such as elastic fibre destruction, mucoid accumulation, and smooth muscle cell apoptosis are co-localized in aneurysms of the ascending aorta of various aetiologies. Recent experimental studies reported an activation of TGF-beta in aneurysms related to Marfan (and Loeys-Dietz) syndrome. Here we investigate TGF-beta signalling in normal and pathological human ascending aortic wall in syndromic and non-syndromic aneurysmal disease. Aneurysmal ascending aortic specimens, classified according to aetiology: syndromic MFS (n = 15, including two mutations in TGFBR2), associated with BAV (n = 15) or degenerative forms (n = 19), were examined. We show that the amounts of TGF-beta1 protein retained within and released by aneurysmal tissue were greater than for control aortic tissue, whatever the aetiology, contrasting with an unchanged TGF-beta1 mRNA level. The increase in stored TGF-beta1 was associated with enhanced LTBP-1 protein and mRNA levels. These dysregulations of the extracellular ligand are associated with higher phosphorylated Smad2 and Smad2 mRNA levels in the ascending aortic wall from all types of aneurysm. This activation correlated with the degree of elastic fibre fragmentation. Surprisingly, there was no consistent association between the nuclear location of pSmad2 and extracellular TGF-beta1 and LTBP-1 staining and between their respective mRNA expressions. In parallel, decorin was focally increased in aneurysmal media, whereas biglycan was globally decreased in aneurysmal aortas. In conclusion, this study highlights independent dysregulations of TGF-beta retention and Smad2 signalling in syndromic and non-syndromic aneurysms of the ascending aorta.

Detection of pathological aortic tissues by infrared multispectral imaging and chemometrics

Processing of multispectral images is becoming an important issue, especially in terms of data mining for disease diagnosis. We report here an original image analysis procedure developed in order to compare 42 infrared multispectral images acquired on human ascending aortic healthy and pathological tissues. Each image contained about 2500 infrared absorption spectra, each composed of 1641 variables (wavenumbers). To process this large data set, we have restricted the spectral window used to the 1800-950 cm(-1) spectral range and selected 100 spectra from the aortic media, which is the most altered part of the aortic tissue in aneurysms. Prior to this selection, a spectral quality test was performed to eliminate 'bad' spectra. Our data set was first subjected to a discriminant analysis, which allowed separation of aortic tissues in two groups corresponding respectively to normal and aneurysmal states. Then a K-means analysis, based on 20 groups, allowed reconstruction of infrared images using false-colours and discriminated between pathological and healthy tissues. These results demonstrate the usefulness of such data processing methods for the analysis and comparison of a set of spectral images.

Quantitative Analysis of ECG-Gated High-Resolution Contrast-Enhanced MR Angiography of the Thoracic Aorta

OBJECTIVE

The purpose of this study was to evaluate the effect of cardiac gating on the quality of images of the thoracic aorta at various levels during contrast-enhanced MR angiography compared with MR angiography without cardiac gating.

MATERIALS AND METHODS

Fifty patients underwent high-resolution contrast-enhanced MR angiography on a 1.5-T whole-body system. The 50 patients were composed of two groups of 25 consecutive patients; one group underwent MR angiography with ECG gating and the other group underwent MR angiography without ECG gating. A sagittal (3D) gradient-echo fast low-angle shot (FLASH) sequence (TR/TE, 2.8/1.4; flip angle, 25 degrees; readout, 512; voxel size, 1.4 x 0.8 x 1.3 mm) with an asymmetric k-space scanning scheme in all three gradient axes was used, and 0.2 mmol/kg of gadopentetate dimeglumine was injected at 2 mL/s. Sharpness of the thoracic aorta was evaluated at three levels by generating a signal intensity profile across the aortic vessel wall and calculating the distance between two points along a line representing the slope of the signal intensity profile. Both sides of the intensity profile were analyzed and averaged and then used to calculate sharpness. An additional group of six patients was included who had undergone both a gated and an ungated sequence; results of this group were analyzed independently.

RESULTS

Quantitative analysis of the sharpness of the ascending thoracic aorta showed a significant increase in sharpness in both the 50-patient and six-patient groups (p < 0.005) with the addition of cardiac gating.

CONCLUSION

Cardiac gating significantly improves the sharpness of the ascending aorta, a portion of the aorta that is subject to a great deal of blurring caused by cardiac motion. High-resolution contrast-enhanced MR angiography with cardiac gating can produce high quality images of the thoracic vasculature, thus enabling accurate diagnosis of vessel disease.

The modified Bentall procedure for aortic root replacement

The Bentall procedure is a surgical repair of an ascending aortic or aortic root aneurysm in combination with aortic valve disease. Less commonly, it is used to repair aortic dissection affecting the aortic root and valve. During the procedure, a composite aortic valve graft is used to replace the proximal ascending aorta and aortic valve. The procedure is performed through a median sternotomy during cardiopulmonary bypass. In this modification of the original procedure, coronary artery circulation is maintained by removing a full-thickness "button" of aorta surrounding the coronary ostia, making it easier to implant the proximal end of the coronary arteries into openings made in the aortic vascular graft.

Chest Pain: A Clinical Assessment

Chest pain is one of the most common presentations in emergency medicine. The initial evaluation should always consider life-threatening causes such as aortic dissection, pulmonary embolism, pneumothorax, pneumomediastinum, pericarditis, and esophageal perforation. Radiographic imaging is performed in tandem with the initial clinical assessment and stabilization of the patient. Radiologic findings are key to diagnosis and management of this entity.