Commercial Air Travel for Passengers With Cardiovascular Disease: Recommendations for Less Common Conditions, Considerations for Venous Thromboembolism, and General Guidance

The accelerated growth of commercial flights has resulted in a huge upswing of air travelers over the last few decades, including passengers with a wide range of cardiovascular conditions. Notwithstanding the ongoing COVID-19 pandemic that has set back the aviation industry for the next 1-2 years, air travel is expected to rebound fully by 2024. Guidelines and evidence-based recommendations for safe air travel in this group vary, and physicians often encounter situations where opinions and assessments on fitness for flights are sought. This article aims to provide an updated suite of recommendations for the aeromedical disposition of passenger with uncommon cardiovascular conditions, such as congenital heart diseases, inflammatory cardiac conditions (endocarditis/pericarditis/myocarditis), pulmonary hypertension, and venous thromboembolism. In addition, the article also aims to provide practical general guidance for the aeromedical examiner in evaluating, preparing, and optimizing the cardiac status of the patient with cardiovascular ailments for air travel.

Coronavirus Disease 2019 and the Myocardium

Infection with the coronavirus known as COVID-19 has promoted growing interest on the part of cardiologists, emergency care specialists, intensive care specialists, and researchers, due to the study of myocardial involvement based on different clinical forms resulting from immunoinflammatory and neurohumoral demodulation.Myocardial involvement may be minimal and identifiable only by electrocardiographic changes, mainly increased cardiac troponins, or, on the other side of the spectrum, by forms of fulminant myocarditis and takotsubo syndrome.The description of probable acute myocarditis has been widely supported by the observation of increased troponin in association with dysfunction. Classical definition of myocarditis, supported by endomyocardial biopsy of inflammatory infiltrate, is rare; it has been observed in only one case report to date, and the virus has not been identified inside cardiomyocytes.Thus, the phenomenon that has been documented is acute myocardial injury, making it necessary to rule our obstructive coronary disease based on increased markers of myocardial necrosis, whether or not they are associated with ventricular dysfunction, likely associated with cytokine storms and other factors that may synergistically promote myocardial injury, such as sympathetic hyperactivation, hypoxemia, arterial hypotension, and microvascular thrombotic phenomena.Systemic inflammatory and myocardial phenomena following viral infection have been well documented, and they may progress to cardiac remodeling and myocardial dysfunction. Cardiac monitoring of these patients is, therefore, important in order to monitor the development of the phenotype of dilated myocardiopathy.This review presents the main etiological and physiopathological findings, a description of the taxonomy of these types of cardiac involvement, and their correlation with the main clinical forms of the myocardial component present in patients in the acute phase of COVID-19.

A hexavalent Coxsackievirus B vaccine is highly immunogenic and has a strong protective capacity in mice and nonhuman primates

Coxsackievirus B (CVB) enteroviruses are common human pathogens known to cause severe diseases including myocarditis, chronic dilated cardiomyopathy, and aseptic meningitis. CVBs are also hypothesized to be a causal factor in type 1 diabetes. Vaccines against CVBs are not currently available, and here we describe the generation and preclinical testing of a novel hexavalent vaccine targeting the six known CVB serotypes. We show that the vaccine has an excellent safety profile in murine models and nonhuman primates and that it induces strong neutralizing antibody responses to the six serotypes in both species without an adjuvant. We also demonstrate that the vaccine provides immunity against acute CVB infections in mice, including CVB infections known to cause virus-induced myocarditis. In addition, it blocks CVB-induced diabetes in a genetically permissive mouse model. Our preclinical proof-of-concept studies demonstrate the successful generation of a promising hexavalent CVB vaccine with high immunogenicity capable of preventing CVB-induced diseases.

Dilated cardiomyopathies and non-compaction cardiomyopathy

Dilated cardiomyopathy (DCM) is the most common form of cardiomyopathy and one of the most common causes of heart failure. It is characterized by left or biventricular dilation and a reduced systolic function. The causes are manifold and range from myocarditis to alcohol and other toxins, to rheumatological, endocrinological, and metabolic diseases. Peripartum cardiomyopathy is a special form that occurs at the end of or shortly after pregnancy. Genetic mutations can be detected in approximately 30-50% of DCM patients. Owing to the growing possibilities of genetic diagnostics, increasingly more triggering variants and hereditary mechanisms emerge. This is particularly important with regard to risk stratification for patients with variants with an increased risk of arrhythmias. Patient prognosis is determined by the occurrence of heart failure and arrhythmias. In addition to the treatment of the underlying disease or the elimination of triggering harmful toxins, therapy consists in guideline-directed heart failure treatment including drug and device therapy.

Stop that glucose getting to heart!

Cardiac inflammation/infection imaging with 18F-FDG has been very useful in guiding patient management in conditions such as cardiac sarcoidosis, myocarditis, device infections, and prosthetic implant-related infections. Various protocols have been described to suppress normal myocardial glucose uptake. Certainly, there is need for standardization of protocols but adaptation of protocol to suit individual patient needs is also equally important. In the current article in this issue, Alexandra Clément et al have shown that a 7-day ketogenic diet can be used as an alternative method in mice models. This may work well in humans who are unable to fast.

[Myocarditis]

When dealing with myocarditis in clinical practice, it is important to consider the possibility of myocarditis in suspected cases and to manage quickly and properly for hemodynamic compromise. Regarding the diagnosis, electrocardiographic alteration such as ST-T abnormalities and to measuring the serum levels of cardiac troponin T or I, leading to the adequate consultation for cardiologists. When diagnosed as myocarditis, the patients should be transferred to advanced medical care hospitals possessing cardiac catheterization laboratory and coronary care unit. Immunomoduratory treatments including steroid pulse therapy are strongly recommended for myocarditis due to immune-related adverse events.

[Clinical and morphological observation of Löffler's endomyocarditis]

The article describes the case of a 42-year-old young woman with Löffler's endomyocarditis (fibroplastic endomyocarditis with eosinophilic syndrome). Pathomorphological (macroscopic and histological) criteria for the diagnosis of this rare form of restrictive cardiomyopathy are presented.

Clinical perspective on the myocarditis and cardiomyopathies

Myocardial diseases are often encountered in cardiology and pose a significant diagnostic challenge. Myocarditis is an acute inflammatory disease of the heart muscle. Pathophysiology of myocarditis is a complex interplay of genetic background, innate immunity, viral or bacterial agents and formation of autoreactive antibodies and lymphocytes that maintain the inflammation after the infection was eliminated. Differentiation of myocardial infarction or heart failure of different etiology is crucial in the acute stage. Cardiac magnetic resonance imaging (MRI) enables with sufficient sensitivity and specificity diagnosis of myocardial inflammation and scar. Endomyocardial biopsy (EMB) with histology and immunohistochemistry is a gold standard for detection of myocarditis. EMB is indicated in selected patients with life-threatening symptoms where EMB may have therapeutic consequences. Giant cell myocarditis and eosinophilic myocarditis are specific examples of such a condition. Polymerase chain reaction (PCR) of the myocardial sample is used to detect viral genome. Serum antibodies or PCR from blood are not helpful in determining the etiology of myocarditis. Viral presence in myocardium is found in patients who do not have histological evidence of myocarditis which makes the association of positive PCR and etiology of myocarditis obscure. Cardiomyopathies (CMP) are characterized by structural and functional cardiac abnormalities that cannot be explained by coronary artery disease or abnormal loading conditions (valvular disease, arterial hypertension, congenital heart disease). CMP are classified based on the prevailing morphology regardless of primary (genetic, idiopathic) or secondary (systemic disease) etiology. European Society of Cardiology defines five types of CMP: hypertrophic, dilated, restrictive, arrhythmogenic and unclassified. CMP diagnosis is based on the imaging with echocardiography, coronary angiography, invasive hemodynamics and cardiac MRI. EMB is rarely indicated in dilated or restrictive CMP. Genetic testing is used to determine pathogenic mutations in phenotype positive patients and in familiar screening. Genetically determined CMP are mostly monogenic and autosomal dominant. Incomplete penetrance and variable expressivity cause variable or even negative phenotypes in genotype positive individuals. Genetic screening of a large number of genes and non-coding DNA results in findings of many variants of uncertain significance which make the interpretation of the genetic testing difficult.

Histopathological diagnosis of myocarditis

Histopathological assessment of the endomyocardial biopsy represents a gold standard in diagnosis of myocarditis (MC). For a long time, the microscopic diagnosis relied on Dallas criteria. They defined MC on morphological grounds as a presence of inflammatory infiltrate accompanied by signs of myocyte damage. However, these criteria were abandoned due to large proportion of false negative results and substantial interpersonal variability in the histopathological evaluation. The immunohistochemistry was implemented in the diagnostic process as well. Morphological classification of MC is based on the type of the inflammatory infiltration. The most common type of MC in the routine bioptic practice is lymphocytic MC. Giant cell, granulomatous, neutrophilic and eozinophilic MC are less frequent. The aim of this work is to inform about the current level of knowledge in histopathological diagnostics of MC and, in relation to previous article “ Štěchovský, Adla, Bonaventura: Clinical perspective on the myocarditis and cardiomyopathies”, discuss also a different clinical and pathological view on this group of diseases.

Increased Total Serum Immunoglobulin E in Children Developing Mycoplasma pneumoniae-related Extra-pulmonary Diseases

Mycoplasma pneumoniae has been recognized to be involved in several extra-pulmonary diseases, but the underlying immunologic mechanisms are still largely unknown. Recently, we observed a significant elevation of serum Immunoglobulin E (IgE) in a small group of these children. Here, we assessed total serum IgE levels in children affected with Mycoplasma pneumoniae-related extra-pulmonary diseases. We prospectively collected the data of 162 children admitted to the hospital (because of respiratory infections or extra-pulmonary diseases) who were evaluated for Mycoplasma pneumoniae serology and total serum IgE levels, concomitantly. Based upon clinical and serology aspects, 3 groups of children were identified: I) with non-mycoplasma respiratory disease; II) with mycoplasma-related respiratory diseases; III) with extra-pulmonary diseases related to concomitant/recent Mycoplasma pneumoniae infection. Interestingly, children with Mycoplasma pneumoniae-related extra-pulmonary diseases showed a significant elevation of total serum IgE. In particular, patients developing Mycoplasma pneumoniae-related extra-pulmonary diseases (group III) showed significantly higher level of IgE than both previous groups (p<0.001 vs. group I; p<0.01 vs. group II). In conclusion, hospitalized children diagnosed with Mycoplasma pneumoniae-related extra-pulmonary diseases resulted to have significantly increased serum IgE compared to children developing respiratory illnesses only.

You're the Flight Surgeon

Netters TA Jr. You're the flight surgeon: chest discomfort in a flyer. Aerosp Med Hum Perform. 2018; 89(9):851-853.

Overlooking cardiac dysfunction triggered by immune checkpoint inhibitors: Caution, trespassers will be ventilated

Immune-related cardiac adverse events can ensue following immunotherapies.

Checkpoint Inhibitors May Induce Myocarditis

Myocarditis is a rare but serious side effect that can occur in patients receiving immune checkpoint inhibitors. To better understand the condition, researchers analyzed the symptoms, timing, demographics, and treatment outcomes for 101 patients who developed it following treatment.

Fragment-growing guided design of Keap1-Nrf2 protein-protein interaction inhibitors for targeting myocarditis

Small-molecule inhibitors that block the Keap1-Nrf2 protein-protein interactions are being intensely pursued as a new therapeutic strategy for oxidative stress-related diseases, such as cancer, diabetes, Alzheimer's disease, arteriosclerosis, inflammation and myocarditis. However, there are not enough studies on antioxidant treatments using small molecules in myocarditis. We herein provided a series of novel hydronaphthoquinones as the Keap1-Nrf2 interaction inhibitors targeting LPS-induced myocarditis both in vitro and in vivo. These compounds were designed through an in-silico fragment growing approach based on our previous reported compound, S47 (1). The new compounds were predicted to form additional hydrogen bonds with the S363 residue, leading to higher inhibitory activity. Among these new derivatives, compounds S01 and S05 emerged as inhibitors with significant biochemical potency, as determined by fluorescent anisotropy assay and confirmed by surface plasmon resonance (SPR) and differential scanning fluorimetry (DSF) assays. These inhibitors can dose-dependently protect the H9c2 cardiac cells against LPS-induced injury (100% at 2 μM and 4 μM) and effectively prolong survival or save the life of LPS-injured mice. Mechanistic studies showed that these inhibitors could release Nrf2 in H9c2 cells and LPS-inflammatory mouse models and translocate into the nucleus in a dose-response manner, which significantly increased the downstream genes (HO-1, NQO-1) and the pro-inflammatory cytokines (TNF-α, IL-1β, IL-6), while ROS production dramatically decreased. Their protective effects and the mechanism of action were further confirmed by siNrf2 transfected experiment. Collectively, the novel hydronaphthoquinones can be used as promising lead compounds for the study of Keap1-Nrf2 protein-protein interactions and further anti-myocarditis drug development.

Small interfering RNA therapy against carbohydrate sulfotransferase 15 inhibits cardiac remodeling in rats with dilated cardiomyopathy

Carbohydrate sulfotransferase 15 (CHST15) is a sulfotransferase responsible for biosynthesis of chondroitin sulfate E (CS-E), which plays important roles in numerous biological events such as biosynthesis of proinflammatory cytokines. However, the effects of CHST15 siRNA in rats with chronic heart failure (CHF) after experimental autoimmune myocarditis (EAM) have not yet been investigated. CHF was elicited in Lewis rats by immunization with cardiac myosin, and after immunization, the rats were divided into two groups and treated with either CHST15 siRNA (2μg/week) or vehicle. Age matched normal rats without immunizations were also included in this study. After 7weeks of treatment, we investigated the effects of CHST15 siRNA on cardiac function, proinflammatory cytokines, and cardiac remodeling in EAM rats. Myocardial functional parameters measured by hemodynamic and echocardiographic studies were significantly improved by CHST15 siRNA treatment in rats with CHF compared with that of vehicle-treated CHF rats. CHST15 siRNA significantly reduced cardiac fibrosis, and hypertrophy and its marker molecules (left ventricular (LV) mRNA expressions of transforming growth factor beta1, collagens I and III, and atrial natriuretic peptide) compared with vehicle-treated CHF rats. CHF-induced increased myocardial mRNA expressions of proinflammatory cytokines [interleukin (IL)-6, IL-1β], monocyte chemoattractant protein-1, and matrix metalloproteinases (MMP-2 and -9), and CHST15 were also suppressed by the treatment with CHST15 siRNA. Western blotting study has confirmed the results obtained from mRNA analysis as CHST15 siRNA treated rats expressed reduced levels of inflammatory and cardiac remodeling marker proteins. Our results demonstrate for the first time, that CHST15 siRNA treatment significantly improved LV function and ameliorated the progression of cardiac remodeling in rats with CHF after EAM.

[Establishment of human cardiac C protein induced experimental autoimmune myocarditis model in rat]

OBJECTIVE

To construct the recombinant plasmid of human cardiac C protein (CCP) peptide with immunogenicity and to express, purification and renature fusion protein. The fusion protein was injected to Lewis rats to establish experimental autoimmune myocarditis (EAM) model.

METHODS

Total RNA was extracted from human heart and used as the template for reverse transcriptase-directed cDNA synthesis. The cDNA was then amplified by polymerase chain reaction (PCR) using oligonucleotide primers specific for CCP peptide with immunogenicity. Subsequently, the purified CCP peptide gene was cloned into PEASY-T1 vector and the ligated product was identified by PCR and DNA sequence analysis. Then the CCP target gene of positive clone was inserted into the pQE30, a prokaryotic expression vector, and the inserting plasmid was transformed into Escherichia coli. host M15. The positive clone extracted from the bacterium liquid was sieved by insertional inactivation sieve method and identified by PCR of bacterium liquid, CCP immunological peptide was purified and renatured in semipermeable membrane. EAM model in Lewis rats was induced by injection of mixture of 100 µg CCP fusion protein immunological peptide and 2.5 g/L completed Freund adjuvant from two double foot pad and subsequent abdominal injection of 0.5 µg pertussis toxin. Two, four, six, and eight weeks after immunization, hemodynamic evaluation was made and hearts underwent histological examination.

RESULTS

The DNA sequence analysis for cloning vector extraction revealed that the CCP target gene was cloned into pQE30 exactly. The DNA of 1000 bp length was obtained by PCR examination of bacterium liquid with transformation of express recombinants which were consistent with the expected size. Purified fusion protein in vertical slab gel electrophoresis showed 35 000 as expected. The recombinant CCP fusion protein existed in inclusion bodies of E. coli and amounted to 80% - 90% of the total protein. Hemodynamic and histological evaluations showed typical acute inflammatory responses at 2 weeks, subacute inflammatory and fibrosis changes at 4 weeks after injection, and signs of chronic dilated cardiomyopathy at 6 weeks post injection.

CONCLUSION

Combination of gene clone technique and histidine tag protein purification technique can be used to synthesize human cardiac C protein to induce EAM model in Lewis rat.

Imaging myocardial inflammation of various etiologies with 99mTc-depreotide SPET/CT

Previous reports suggested the accumulation of technetium-99m-depreotide trifluoroacetate ((99m)Tc-D) at the sites of active infection or inflammation. Binding of depreotide to over-expressed somatostatin receptors in activated lymphocytes and macrophages probably accounts for the depiction of inflammation. We speculated that myocardial inflammation could also be illustrated by (99m)Tc-D scintigraphy. We report on 3 patients with the clinical diagnosis of myocarditis of various etiologies, in which (99m)Tc-D SPET/CT demonstrated obvious tracer uptake in the myocardium of the left ventricle. In conclusion, we suggest that depreotide imaging can depict myocardial inflammation, thus supporting clinical diagnosis.

The role of endocarditis, myocarditis and pericarditis in qualitative and quantitative data analysis

The current study is the first scientometric analysis of research activity and output in the field of inflammatory disorders of the heart (endo-, myo- and pericarditis). Scientometric methods are used to compare scientific performance on national and on international scale to identify single areas of research interest. Interest and research productivity in inflammatory diseases of the heart have increased since 1990. The majority of publications about inflammatory heart disorders were published in Western Europe and North America. The United States of America had a leading position in terms of research productivity and quality; half of the most productive authors in this study came from American institutions. The analysis of international cooperation revealed research activity in countries that are less established in the field of inflammatory heart disorder research, such as Brazil, Saudi Arabia and Tunisia. These results indicate that future research of heart inflammation may no longer be influenced predominantly by a small number of countries. Furthermore, this study revealed weaknesses in currently established scientometric parameters (i.e., h-index, impact factor) that limit their suitability as measures of research quality. In this respect, self-citations should be generally excluded from calculations of h-index and impact factor.