Radiation-associated cardiovascular disease

Radiation metabolomics in the quest of cardiotoxicity biomarkers: the review

Purpose: Ionizing radiation is a risk factor to the whole organism, including the heart. Cardiac damage is considered to be a late effect of radiation exposure. While the acute cardiotoxicity of high doses is well characterized, the knowledge about nature and magnitude of the cardiac risk following lower doses exposure is incomplete. It has been shown that the cardiotoxic effects of radiation are source-, dose- and time-dependent. This paper provides an overview on these dependencies with regard to the molecular responses at the cellular and tissue levels. Main focus is put on the Nuclear Magnetic Resonance (NMR)-based and Mass Spectrometry (MS)-based metabolomic approaches in search of toxicity markers of relatively small doses of radiation.Conclusions: Available literature indicates that radiation exposure affects metabolites associated with: energy production, degradation of proteins and cell membranes, expression of proteins and stress response. Such effects are common for both animal and human studies. However, the specific metabolic response depends on several factors, including the examined organ. Radiation metabolomics can be used to explain the mechanisms of development of radiation-induced heart disease and to find an organ-specific biomarker of radiation exposure. The main aim of this review was to collect the information on the human cardiotoxicity biomarkers. In addition it also summarizes results of the studies on the metabolic responses to ionizing radiation for other organs, as well as the comparative data concerning animal studies.

Pathology of radiation induced heart disease

The aim of this paper is dual - to review the relevant literature on pathology of radiation induced heart disease (RIHD), and to present an illustrative case of our own. Therapeutic ionizing radiation, such as that used in the treatment of Hodgkin´s lymphoma and cancers of left breast, lungs, esophagus, and thymus, can cause cardiac damage that may take several years to manifest. The spectrum of RIHD is broad and includes [1] pericarditis and pericardial effusion; [2] endocardial fibrosis and valvular dysfunction; [3] nonischemic myocardial fibrosis; [4] obstructive coronary artery disease with resultant myocardial ischemia; [5] damage to the great vessels; and [6] conduction system dysfunction. Pericardial disease, however, is the most common manifestation of mediastinal irradiation. A case is described of a typical RIHD in a 52-year-old female who died from heart failure with a history of mediastinal neuroblastoma operated and irradiated at the age of 9 years. Her autopsy heart lesions comprised chronic and acute pericarditis with constrictive features, myocardial fibrosis with features of restrictive cardiomyopathy and fibrosis with calcification of the left heart valves. As a unique lesion, there were small calcifications in the mural endocardium and in the large arterial intima. This finding seems to be diagnostic for RIHD.

Dosimetric comparison of three-dimensional conformal radiotherapy and intensity-modulated radiotherapy for left-sided chest wall and lymphatic irradiation

Introduction

The aim of this study was to compare five different techniques for chest wall (CW) and lymphatic irradiation in patients with left‐sided breast carcinoma.

Methods

Three‐dimensional conformal radiotherapy (3DCRT), forward‐planned intensity‐modulated radiotherapy (FP‐IMRT), inverse‐planned IMRT (IP‐IMRT; 7‐ or 9‐field), and hybrid IP‐/FP‐IMRT were compared in 10 patients. Clinical target volume (CTV) included CW and internal mammary (IM), supraclavicular (SC), and axillary nodes. Planning target volumes (PTVs), CTVs, and organs at risks (OARs) doses were analyzed with dose–volume histograms (DVHs).

Results

No differences could be observed among the techniques for doses received by 95% of the volume (D95%) of lymphatics. However, the FP‐IMRT resulted in a significantly lower D95% dose to the CW‐PTV compared to other techniques (P = 0.002). The 9‐field IP‐IMRT achieved the lowest volumes receiving higher doses (hotspots). Both IP‐IMRT techniques provided similar mean doses (Dmean) for the left lung which were smaller than the other techniques. There was no difference between the techniques for maximum dose (Dmax) of right breast. However, FP‐IMRT resulted in lower Dmean and volume of right breast receiving at least 5 Gy doses compared to other techniques.

Conclusion

The dose homogeneity in CW‐CTV was better using IMRT techniques compared to 3DCRT. Especially 9‐field IP‐IMRT provided a more homogeneous dose distribution in IM and axillary CTVs. Moreover, the OARs volumes receiving low radiation doses were larger with IP‐IMRT technique, while volumes receiving high radiation doses were larger with FP‐IMRT technique. Hybrid IMRT plans were found to have the advantages of both FP‐ and IP‐IMRT techniques.

New therapeutic insights into radiation-induced myocardial fibrosis

Radiation therapy (RT) for the treatment of thoracic tumors causes radiation-induced heart disease (RIHD). Radiation-induced myocardial fibrosis (RIMF) is both an acute and chronic stage of RIHD, depending on the specific pathology, and is thought to be a major risk factor for adverse myocardial remodeling and vascular changes. With the use of more three-dimensional conformal radiation regimens and early screenings and diagnoses for RIMF, the incidence of RIHD is declining, but it still must be carefully investigated to minimize the mortality and morbidity of patients with thoracic malignancies after RT treatment. Effective methods for preventing RIMF involve a decrease in the direct radiation dose in the heart, and early screening and diagnosis. Medications remain as a useful adjunct for preventing or treating RIMF. This review mainly discusses the cellular and molecular mechanisms underlying RIMF, and new therapeutic drugs that can potentially be developed from this knowledge.

Radiation-Associated Pericardial Disease

PURPOSE OF REVIEW

This review highlights the literature related to pericardial injury following radiation for oncologic diseases.

RECENT FINDINGS

Radiation-associated pericardial disease can have devastating consequences. Unfortunately, there is considerably less evidence regarding pericardial syndromes following thoracic radiation as compared to other cardiovascular outcomes. Pericardial complications of radiation may arise acutely or have an insidious onset several decades after treatment. Transthoracic echocardiography is the screening imaging modality of choice, while cardiac magnetic resonance imaging further characterizes the pericardium and guides treatment decision-making. Cardiac CT can be useful for assessing pericardial calcification. Ongoing efforts to lessen inadvertent cardiac injury are directed towards the revision of radiation techniques and protocols. As survival of mediastinal and thoracic malignancies continues to improve, radiation-associated pericardial disease is increasingly relevant. Though advances in radiation oncology demonstrate promise in curtailing cardiotoxicity, the long-term effects pertaining to pericardial complications remain to be seen.

Clinical Outcomes after Transcatheter Aortic Valve Replacement in Cancer Survivors Treated with Ionizing Radiation

BACKGROUND

Improved cancer survival in patients treated with thoracic ionizing radiation (XRT) has resulted in unanticipated surge of aortic stenosis. Transcatheter aortic valve replacement (TAVR) has revolutionized the management of severe aortic stenosis. However, long-term clinical outcomes in radiation-exposed cohorts undergoing TAVR are unknown. We compared the all-cause mortality and major adverse cardiac events (MACE) in patients with prior chest XRT (C-XRT) undergoing TAVR.

METHODS

This is an observational cohort study in subjects who underwent TAVR for symptomatic severe aortic stenosis from 2012 to 2017 in a tertiary care referral center. We examined the all-cause mortality and MACE using cox proportional hazard analysis to identify the clinical predictors of survival in the cohort of patients who had a history of prior C-XRT for malignancy.

RESULTS

Of the 610 patients who underwent TAVR for symptomatic severe aortic stenosis, 75 had prior C-XRT. The majority of C-XRT patients had prior breast cancer (44%) followed by Hodgkin's lymphoma (31%), with the median time from XRT to TAVR of 19.0 years. During a mean follow up of 17.1 months after TAVR, all-cause mortality was 17%. Those with prior C-XRT had higher all-cause mortality (XRT: 29%; non-XRT:15%, p<0.01) and MACE (XRT: 57%; non-XRT: 27%, p<0.001) after TAVR. Patients with prior XRT had a higher incidence of atrial fibrillation (XRT: 48 %; non-XRT: 2.4%, p<0.01) and high-grade heart block (XRT: 20%; non-XRT: 9.1%, p=0.007) requiring pacemaker implant after TAVR. On multivariate cox proportional hazard analysis, prior XRT (HR: 2.07, p=0.003), poor renal function (HR: 1.29, p<0.001) and post-operative anemia requiring transfusion (HR: 1.16, p:0.001) were the strongest predictors of reduced survival.

CONCLUSIONS

Cancer survivors with prior C- XRT have higher incidence of all-cause mortality and MACE after TAVR. Careful patient selection and follow-up strategies are needed to improve outcomes.

Selective Heart Irradiation Induces Cardiac Overexpression of the Pro-hypertrophic miR-212

Background: A deleterious, late-onset side effect of thoracic radiotherapy is the development of radiation-induced heart disease (RIHD). It covers a spectrum of cardiac pathology including also heart failure with preserved ejection fraction (HFpEF) characterized by left ventricular hypertrophy (LVH) and diastolic dysfunction. MicroRNA-212 (miR-212) is a crucial regulator of pathologic LVH via FOXO3-mediated pathways in pressure-overload-induced heart failure. We aimed to investigate whether miR-212 and its selected hypertrophy-associated targets play a role in the development of RIHD. Methods: RIHD was induced by selective heart irradiation (50 Gy) in a clinically relevant rat model. One, three, and nineteen weeks after selective heart irradiation, transthoracic echocardiography was performed to monitor cardiac morphology and function. Cardiomyocyte hypertrophy and fibrosis were assessed by histology at week 19. qRT-PCR was performed to measure the gene expression changes of miR-212 and forkhead box O3 (FOXO3) in all follow-up time points. The cardiac transcript level of other selected hypertrophy-associated targets of miR-212 including extracellular signal-regulated kinase 2 (ERK2), myocyte enhancer factor 2a (MEF2a), AMP-activated protein kinase, (AMPK), heat shock protein 40 (HSP40), sirtuin 1, (SIRT1), calcineurin A-alpha and phosphatase and tensin homolog (PTEN) were also measured at week 19. Cardiac expression of FOXO3 and phospho-FOXO3 were investigated at the protein level by Western blot at week 19. Results: In RIHD, diastolic dysfunction was present at every time point. Septal hypertrophy developed at week 3 and a marked LVH with interstitial fibrosis developed at week 19 in the irradiated hearts. In RIHD, cardiac miR-212 was overexpressed at week 3 and 19, and FOXO3 was repressed at the mRNA level only at week 19. In contrast, the total FOXO3 protein level failed to decrease in response to heart irradiation at week 19. Other selected hypertrophy-associated target genes failed to change at the mRNA level in RIHD at week 19. Conclusions: LVH in RIHD was associated with cardiac overexpression of miR-212. However, miR-212 seems to play a role in the development of LVH via FOXO3-independent mechanisms in RIHD. As a central regulator of pathologic remodeling, miR-212 might become a novel target for RIHD-induced LVH and heart failure.

Mortality from heart diseases following occupational radiation exposure: analysis of the National Registry for Radiation Workers (NRRW) in the United Kingdom

Statistically significant increases in heart disease (HD) mortality with cumulative recorded occupational radiation dose from external sources were observed among 174 541 subjects, who were predominately exposed to protracted low doses over a number of years, and were followed up until the end of 2011 in the UK National Registry for Radiation Workers (NRRW) cohort. Amongst the subtypes of HD, the increasing trends with cumulative dose arose for ischaemic heart disease (IHD) and other HD (which includes pulmonary HD, valve disorders, cardiomyopathy, cardiac dysrhythmias, carditis, conduction disorder and ill-defined HD). For IHD, the increased mortality appears to be at least 20 years after first exposure and the excess risk peaked between 30 and 40 years after the first exposure. There was no evidence of excess risk of IHD mortality for cumulative radiation doses below 0.1 Sv. A categorical analysis also showed that the risk falls below the expected value based on a linear trend, for cumulative doses greater than 0.4 Sv; this smaller risk appears to be primarily associated with workers who started employment at a younger age and who were employed for longer than 30 years, reflecting possible healthy worker survivor effect. This analysis provided further evidence that low doses of radiation exposure may be associated with increased risk of IHD. For other HD, the data suggest an increased risk starting around 40 years after the first exposure. The risk was statistically significant raised only for cumulative doses above 0.4 Sv. However, the number of deaths in this group was small and the results need to be interpreted with caution.

A New Approach for the Prevention and Treatment of Cardiovascular Disorders. Molecular Hydrogen Significantly Reduces the Effects of Oxidative Stress

Cardiovascular diseases are the most common causes of morbidity and mortality worldwide. Redox dysregulation and a dyshomeostasis of inflammation arise from, and result in, cellular aberrations and pathological conditions, which lead to cardiovascular diseases. Despite years of intensive research, there is still no safe and effective method for their prevention and treatment. Recently, molecular hydrogen has been investigated in preclinical and clinical studies on various diseases associated with oxidative and inflammatory stress such as radiation-induced heart disease, ischemia-reperfusion injury, myocardial and brain infarction, storage of the heart, heart transplantation, etc. Hydrogen is primarily administered via inhalation, drinking hydrogen-rich water, or injection of hydrogen-rich saline. It favorably modulates signal transduction and gene expression resulting in suppression of proinflammatory cytokines, excess ROS production, and in the activation of the Nrf2 antioxidant transcription factor. Although H₂ appears to be an important biological molecule with anti-oxidant, anti-inflammatory, and anti-apoptotic effects, the exact mechanisms of action remain elusive. There is no reported clinical toxicity; however, some data suggests that H₂ has a mild hormetic-like effect, which likely mediate some of its benefits. The mechanistic data, coupled with the pre-clinical and clinical studies, suggest that H₂ may be useful for ROS/inflammation-induced cardiotoxicity and other conditions.

Cardiomyopathy in Children: Classification and Diagnosis: A Scientific Statement From the American Heart Association

In this scientific statement from the American Heart Association, experts in the field of cardiomyopathy (heart muscle disease) in children address 2 issues: the most current understanding of the causes of cardiomyopathy in children and the optimal approaches to diagnosis cardiomyopathy in children. Cardiomyopathies result in some of the worst pediatric cardiology outcomes; nearly 40% of children who present with symptomatic cardiomyopathy undergo a heart transplantation or die within the first 2 years after diagnosis. The percentage of children with cardiomyopathy who underwent a heart transplantation has not declined over the past 10 years, and cardiomyopathy remains the leading cause of transplantation for children >1 year of age. Studies from the National Heart, Lung, and Blood Institute-funded Pediatric Cardiomyopathy Registry have shown that causes are established in very few children with cardiomyopathy, yet genetic causes are likely to be present in most. The incidence of pediatric cardiomyopathy is ≈1 per 100 000 children. This is comparable to the incidence of such childhood cancers as lymphoma, Wilms tumor, and neuroblastoma. However, the published research and scientific conferences focused on pediatric cardiomyopathy are sparcer than for those cancers. The aim of the statement is to focus on the diagnosis and classification of cardiomyopathy. We anticipate that this report will help shape the future research priorities in this set of diseases to achieve earlier diagnosis, improved clinical outcomes, and better quality of life for these children and their families.

Cardiovascular effects of space radiation: implications for future human deep space exploration

BACKGROUND

A manned mission to Mars has been contemplated by the world's largest space agencies for a number of years. The duration of the trip would necessitate a much longer exposure to deep space radiation than any human has ever been exposed to in the past. Concern regarding cancer risk has thus far stalled the progress of deep space exploration; however, the effect of space radiation on the cardiovascular system is significantly less well understood.

DISCUSSION

Damage by radiation in space is mediated by a number of sources, including X-rays, protons and heavier charged atomic nuclei (HZE ions, the high-energy component of galactic cosmic rays). Previously, only lunar mission astronauts have been exposed to significant deep space radiation, with all other missions being low earth orbits only. The effect of this radiation on the human body has been inconclusively studied, and the long-term damage caused to the vascular endothelium by this radiation due to the effect of high-energy particles is not well known.

CONCLUSION

Current radiation shielding technology, which would be viable for use in spacecraft, would not eliminate radiation risk. Similar to how a variety of shielding techniques are used every day by radiographers, again without full risk elimination, we need to explore and better understand the effect of deep space radiation in order to ensure the safety of those on future space missions.

Effects of low-dose oxygen ions and protons on cardiac function and structure in male C57BL/6J mice

PURPOSE

Astronauts traveling beyond low-Earth orbit will be exposed to high linear-energy transfer charged particles. Because there is concern about the adverse effects of space radiation on the cardiovascular system, this study assessed cardiac function and structure and immune cell infiltration in a mouse model of charged-particle irradiation.

MATERIALS AND METHODS

Male C57BL/6 J mice were exposed to oxygen ions (¹⁶O, 600 MeV/n at 0.25-0.26 Gy/min to a total dose of 0, 0.05, 0.1, 0.25, or 1 Gy), protons (150 MeV, 0.35-0.55 Gy/min to 0, 0.5, or 1 Gy), or protons (150 MeV, 0.5 Gy) followed by ¹⁶O (600 MeV/n, 0.1 Gy). Separate groups of mice received ¹³⁷Cs γ-rays (1 Gy/min to 0, 0.5, 1, or 3 Gy) as a reference. Cardiac function and blood velocity were measured with ultrasonography at 3, 5, 7, and 9 months after irradiation. At 2 weeks, 3 months, and 9 months, cardiac tissue was collected to assess apoptosis, tissue remodeling, and markers of immune cells.

RESULTS

Ejection fraction and fractional shortening decreased at 3 and 7 months after ¹⁶O. These parameters did not change in mice exposed to γ-rays, protons, or protons followed by ¹⁶O. Each of the radiation exposures caused only small increases in cleaved caspase-3 and numbers of apoptotic nuclei. Changes in the levels of α-smooth muscle cell actin and a 75-kDa peptide of collagen type III in the left ventricle suggested tissue remodeling, but there was no significant change in total collagen deposition at 2 weeks, 3 months, and 9 months. Increases in protein amounts of cluster of differentiation (CD)2, CD68, and CD45 as measured with immunoblots at 2 weeks, 3 months, and 9 months after exposure to protons or ¹⁶O alone suggested immune cell infiltration. For type III collagen, CD2 and CD68, the efficacy in inducing protein abundance of CD2, CD68, and CD45 was ¹⁶O > protons > γ-rays > protons followed by ¹⁶O.

CONCLUSIONS

Low-dose, high-energy charged-particle irradiation caused mild changes in cardiac function and tissue remodeling in the mouse.

Favourable health-related quality of life reported in survivors of thymic malignancies

OBJECTIVES

The management of patients with locally advanced thymic malignancies remains controversial. Differing combinations of surgical resection, chemotherapy and radiation are used in the management of initial and relapsed disease. Treatment-related toxicities and quality of life could inform therapeutic options. This study describes health utility scores (HUS) in survivors with locally advanced thymic malignancies and investigates the impact of multimodality regimens on HUS.

METHODS

In a cross-sectional study (2014-2017), patients with Masaoka Stage II-IVa thymic malignancies completed various self-reported questionnaires, including EuroQol-5-Dimensions with visual analogue scale (VAS), Eastern Cooperative Oncology Group (ECOG) and Edmonton Symptom Assessment Scale tools. Trimodality versus uni- or bimodality regimens and aggressive versus non-aggressive management of recurrent disease were compared using regression analyses.

RESULTS

Of the 72 patients, 43 (60%) were male with a median age of 58 years, 65 (90%) had thymoma while 7 (10%) had thymic carcinomas; and median time since diagnosis was 50.5 months (range: 3-266). Median HUS and VAS did not differ between groups (trimodality n = 24 vs uni- or bimodality n = 48: HUS = 0.77 vs 0.80, P = 0.29; VAS = 80 vs 75, P = 0.79, respectively). The distributions of patient-reported ECOG were also similar (P = 0.86). Edmonton Symptom Assessment Scale scores for every assessed symptom were similar for different modalities of therapy. Median scores on these tools were also similar regardless of recurrence status or management of relapsed disease (aggressive versus non-aggressive).

CONCLUSION

Survivors with Stage II-IVa thymic malignancies report favourable HUS, VAS and self-reported ECOG with minimal symptom burden. These outcomes may be independent of number and type of initial treatment modalities or management of recurrence.

A clinical prescription for heart health in midlife women

Cardiovascular disease is the leading cause of death in women throughout the United States and Europe. Despite efforts to raise awareness, the sex-specific risk factors are still poorly recognized in both regions, and many women do not identify cardiovascular disease as a primary threat. During midlife, the incidence of cardiovascular disease increases dramatically, and this unique time gives an opportunity to identify both traditional cardiovascular risk factors as well as emerging risk factors unique to women. This review will focus on the current guidelines for cardiovascular risk assessment in Europe and the United States, traditional and emerging cardiovascular risk factors, and preventive lifestyle recommendations for midlife women.

Early diagnosis of cardiotoxic complications of chemotherapy: the possibility of radiation research methods

Oncological diseases are the main causes of death in the world. Modern treatment of cancer patients contributes to an increase in survival rate due to strong chemotherapeutic drugs, the use of which is accompanied by toxic effects on cardiomyocytes. The main manifestations of cardiotoxicity are left ventricular dysfunction, myocardial ischemia, thromboembolic complications, chronic heart failure. As a result, the risk of cardiovascular mortality may be higher than the risk of death from the tumor process. An important task of oncologists and cardiologists is the early diagnosis of cardiotoxic complications in order to start treatment in time and reduce mortality from cardiovascular pathology in cancer patients.

Cardiovascular complications after radiotherapy

Over the past decades, effective cancer therapies have resulted in a significant improvement in the survival rates for a number of cancers and an increase in the number of cancer survivors. Radiation therapy is widely used in the treatment of cancer, and it can induce various cardiotoxicities that differ considerably from chemotherapy-induced cardiotoxicity. They occur primarily as late radiation-induced complications, several years from the end of anticancer treatment and present as coronary artery disease, heart failure, pericardial disease, valvular heart disease and arrhythmias. Patients who recovered from cancer disease suffer from cardiac complications of anticancer treatment, it affects the quality of their lives and life expectancy, especially if the diagnosis is delayed. These patients may present distinct symptoms of cardiac injury, resulting from radiation-induced neurotoxicity and altered pain perception, which makes diagnosis difficult. This review highlights the need for a screening programme for patients who have undergone radiation therapy and which will subsequently have a potentially profound impact on morbidity and mortality.

Radiation-Induced Coronary Artery Disease and Its Treatment: A Quick Review of Current Evidence

As advances in medical technology arise and the availability of cancer treatment increases, an increased number of patients are receiving cancer treatment. Radiation therapy has evolved to become one of the cornerstones of treatment for various types of cancers. One of the long-term consequences of radiation therapy is radiation-induced coronary artery disease (RICAD). Although the pathophysiology of RICAD may be slightly different and more acute onset than the commonly seen “generic” coronary artery disease, it is common practice to treat RICAD in the same method as nonradiation-induced CAD. This paper summarizes the current research available on the topic and shows there is not enough research to obtain significant data about outcomes and restenosis rates of PCI or outcomes of CABG in RICAD. The aim of this review is to create a concise and easy-to-follow review of the relevant data regarding RICAD and hopefully spark further interest in future studies in this field.

Early and late complications following hematopoietic stem cell transplantation in pediatric patients - A retrospective analysis over 11 years

Hematopoietic stem cell transplantation (HSCT) has been an effective method for treating a wide range of malignant or non-malignant disorders. In case of an autologous HSCT, patients receive their own stem cells after myeloablation before extraction. Allogeneic HSCT uses stem cells derived from a donor. Despite being associated with a high risk of early and long-term complications, it is often the last curative option. 229 pediatric patients, who between 1 January 2005 and 31 December 2015 received an HSCT at the University Children’s Hospital Wuerzburg, were studied. Correlations between two groups were calculated with the Chi square test or with a 2x2-contingency table. To calculate metric variables, the Mann-Whitney-U-test was used. Survival curves were calculated according to Kaplan and Meier. Significance was assumed for results with a p-value <0.05 (CI (Confident Interval) 95%). We retrospectively analyzed 229 pediatric patients (105 females, 124 males) for early and late complications of allogeneic and autologous hematopoietic stem cell transplantation. Median age at HSCT was seven years. Underlying diseases were leukemia (n = 73), lymphoma (n = 22), solid tumor (n = 65), CNS (central nervous system)- tumor (n = 41), and “other diseases” (n = 28). Survival times, overall survival, and event-free survival were calculated. Of all patients, 80.8% experienced complications of some degree, including mild and transient complications. Allo-HSCT (allogeneic HSCT) carried a significantly higher risk of complications than auto-HSCT (autologous HSCT) (n = 118 vs. n = 67; p = < .001) and the remission rate after allo-HSCT was also higher (58.7% vs. 44,7%; p = .032). Especially infection rates and pulmonary complications are different between auto- and allo-HSCT. Leukemia patients had the highest risk of early and late complications (95,0%; p < .001). Complications within HSCT are major risk factors following morbidity and mortality. In order to detect complications and risk factors early, strict recordings are needed to reduce the rate of complication by recognition and prevention of triggering factors. In the future, these factors should receive greater attention in the planning of HSCT post-transplantation care in order to improve the results of the transplantation and establish protocols to prevent their occurrence.

Heart toxicity from breast cancer radiotherapy : Current findings, assessment, and prevention

Background

Late cardiac toxicities caused by (particularly left-sided) breast radiotherapy (RT) are now recognized as rare but relevant sequelae, which has prompted research on risk structure identification and definition of threshold doses to heart subvolumes. The aim of the present review was to critically discuss the clinical evidence on late cardiac reactions based on dose-dependent outcome reports for mean heart doses as well as doses to cardiac substructures.

Methods

A literature review was performed to examine clinical evidence on radiation-induced heart toxicities. Mean heart doses and doses to cardiac substructures were focused upon based on dose-dependent outcome reports. Furthermore, an overview of radiation techniques for heart protection is given and non-radiotherapeutic aspects of cardiotoxicity in the multimodal setting of breast cancer treatment are discussed.

Results

Based on available findings, the DEGRO breast cancer expert panel recommends the following constraints: mean heart dose <2.5 Gy; D_meanLV (mean dose left ventricle) < 3 Gy; V5_LV (volume of LV receiving ≥5 Gy) < 17%; V23_LV (volume of LV receiving ≥23 Gy) < 5%; D_meanLAD (mean dose left descending artery) < 10 Gy; V30_LAD (volume of LAD receiving ≥30 Gy) < 2%; V40_LAD (volume of LAD receiving ≥40 Gy) < 1%.

Conclusion

In addition to mean heart dose, breast cancer RT treatment planning should also include constraints for cardiac subvolumes such as LV and LAD. The given constraints serve as a clinicians’ aid for ensuring adequate heart protection. The individual decision between sufficient protection of cardiac structures versus optimal target volume coverage remains in the physician’s hand. The risk of breast cancer-specific mortality and a patient’s cardiac risk factors must be individually weighed up against the risk of radiation-induced cardiotoxicity.

Cardiovascular Care Among Cancer Survivors in the United States

BACKGROUND

Cardiovascular disease (CVD) is a leading cause of mortality among cancer survivors, but whether survivors receive routine cardiovascular monitoring and preventive care has not been well studied. This study uses a population-based dataset to examine this question.

METHODS

Data from the National Health Interview Survey were used to identify 13 266 cancer survivors who completed surveys from 2011 to 2015. Prevalence of CVD and associated risk factors, patterns of doctor visitation, and receipt of CVD preventive care were examined. We used multivariable logistic regression analysis to examine factors associated with the receipt of preventive care for survivors with and without CVD risk factors.

RESULTS

CVD risk factors were prevalent in older cancer survivors 65 years and older (56.9% with hyperlipidemia, 66.8% with hypertension) and younger survivors younger than 50 years (35.4% obese, 30.3% current smokers). Rates of blood pressure, cholesterol, and glucose monitoring were high, but rates of lifestyle modification were lower (54.8% moderate exercise, 47.1% smoking cessation attempts among smokers). Although 71.5% of survivors at 2 years or less from diagnosis saw both general and specialist doctors, only 51.6% of survivors at 5 or more years saw both, and 43.5% saw only a general doctor. On multivariable analysis, receipt of CVD preventive care was strongly associated with general doctor visitation for those with and without CVD risk factors.

CONCLUSIONS

CVD and associated risk factors are prevalent among both older and younger cancer survivors across the United States. This study identifies areas for improvement related to lifestyle modification in survivors, and also highlights the importance of care transition to the primary care provider for long-term survivors.

Radiation and its associated health risks: assessment of knowledge and risk perception among adolescents and young adults in Saudi Arabia

Electromagnetic radiation is the fastest growing environmental factor due to the vast development in technology in the last decades. Awareness about radiation has received more attention worldwide due to its health hazards. Adolescents are exposed to radiation from various sources on a daily basis. The number of studies conducted to assess the knowledge and perception of adolescents and young adults regarding radiation and its risks is limited, especially in the Middle East. The aim of this study was to assess the knowledge and perception about radiation and its associated hazards among adolescents and young adults. Additionally, our aim was to identify the best methods of education regarding radiation and its protective measures. A cross-sectional study was conducted among 506 participants in Saudi Arabia. It was found that the overall knowledge and awareness on radiation sources and its hazards among adolescents and young adults is inadequate. The majority of participants had misconceptions regarding radiation sources and its detriments to health. Socio-demographic variables were associated with the participants' perception. Educating adolescents on radiation and its safety measures is much needed. It was found that the most preferred methods of education are social media and health care providers. The findings of this study will provide insight when designing future interventions to promote specific messages to enhance knowledge and improve awareness regarding radiation.

Cardiovascular Magnetic Resonance in the Oncology Patient

Patients with or receiving potentially cardiotoxic treatment for cancer are susceptible to developing decrements in left ventricular mass, diastolic function, or systolic function. They may also experience valvular heart disease, pericardial disease, or intracardiac masses. Cardiovascular magnetic resonance may be used to assess cardiac anatomy, structure, and function and to characterize myocardial tissue. This combination of features facilitates the diagnosis and management of disease processes in patients with or those who have survived cancer. This report outlines and describes prior research involving cardiovascular magnetic resonance for assessing cardiovascular disease in patients with or previously having received treatment for cancer.

Radiation Matters of the Heart: A Mini Review

Radiation Therapy (RT) has been critical in cancer treatment regimens to date. However, it has been shown that ionizing radiation is also associated with increased risk of damage to healthy tissues. At high radiation doses, varied effects including inactivation of cells in treated tissue and associated functional impairment are seen. These range from direct damage to the heart; particularly, diffuse fibrosis of the pericardium and myocardium, adhesion of the pericardium, injury to the blood vessels and stenosis. Cardiac damage is mostly a late responding end-point, occurring anywhere between 1 and 10 years after radiation procedures. Cardiovascular disease following radiotherapy was more common with radiation treatments used before the late 1980s. Modern RT regimens with more focused radiation beams, allow tumors to be targeted more precisely and shield the heart and other healthy tissues for minimizing the radiation damage to normal cells. In this review, we discuss radiation therapeutic doses used and post-radiation damage to the heart muscle from published studies. We also emphasize the need for early detection of cardiotoxicity and the need for more cardio-protection approaches where feasible.

Quantifying esophageal motion during free-breathing and breath-hold using fiducial markers in patients with early-stage esophageal cancer

Introduction

Cardiac toxicity after definitive chemoradiotherapy for esophageal cancer is a critical issue. To reduce irradiation doses to organs at risk, individual internal margins need to be identified and minimized. The purpose of this study was to quantify esophageal motion using fiducial makers based on four-dimensional computed tomography, and to evaluate the inter-CBCT session marker displacement using breath-hold.

Materials and methods

Sixteen patients with early stage esophageal cancer, who received endoscopy-guided metallic marker placement for treatment planning, were included; there were 35 markers in total, with 9, 15, and 11 markers in the upper thoracic, middle thoracic, and lower thoracic/esophagogastric junction regions, respectively. We defined fiducial marker motion as motion of the centroidal point of the markers. Respiratory esophageal motion during free-breathing was defined as the amplitude of individual marker motion between the consecutive breathing and end-expiration phases, derived from four-dimensional computed tomography. The inter-CBCT session marker displacement using breath-hold was defined as the amplitudes of marker motion between the first and each cone beam computed tomography image. Marker motion was analyzed in the three regions (upper thoracic, middle thoracic, and lower thoracic/esophagogastric junction) and in three orthogonal directions (right-left; anterior-posterior; and superior-inferior).

Results

Respiratory esophageal motion during free-breathing resulted in median absolute maximum amplitudes (interquartile range), in right-left, anterior-posterior, and superior-inferior directions, of 1.7 (1.4) mm, 2.0 (1.5) mm, and 3.6 (4.1) mm, respectively, in the upper thoracic region, 0.8 (1.1) mm, 1.4 (1.2) mm, and 4.8 (3.6) mm, respectively, in the middle thoracic region, and 1.8 (0.8) mm, 1.9 (2.0) mm, and 8.0 (4.5) mm, respectively, in the lower thoracic/esophagogastric region. The inter-CBCT session marker displacement using breath-hold resulted in median absolute maximum amplitudes (interquartile range), in right-left, anterior–posterior, and superior-inferior directions, of 1.3 (1.0) mm, 1.1 (0.7) mm, and 3.3 (1.8) mm, respectively, in the upper thoracic region, 0.7 (0.7) mm, 1.1 (0.4) mm, and 3.4 (1.4) mm, respectively, in the middle thoracic region, and 2.0 (0.8) mm, 2.6 (2.2) mm, and 3.5 (1.8) mm, respectively, in the lower thoracic/esophagogastric region.

Conclusions

During free-breathing, esophageal motion in the superior-inferior direction in all sites was large, compared to the other directions, and amplitudes showed substantial inter-individual variability. The breath-hold technique is feasible for minimizing esophageal displacement during radiotherapy in patients with esophageal cancer.

Heart volume reduction during radiotherapy involving the thoracic region in children: An unexplained phenomenon

BACKGROUND AND PURPOSE

Radiotherapy involving the thoracic region is associated with cardiotoxicity in long-term childhood cancer survivors. We quantified heart volume changes during radiotherapy in children (<18 years) and investigated correlations with patient and treatment related characteristics.

MATERIAL AND METHODS

Between 2010 and 2016, 34 children received radiotherapy involving the thoracic region. We delineated heart contours and measured heart volumes on 114 CBCTs. Relative volume changes were quantified with respect to the volume on the first CBCT (i.e., 100%). Cardiac radiation dose parameters expressed as 2 Gy/fraction equivalent doses were calculated from DVHs. Chemotherapy was categorized as treatment with anthracyclines, alkylating agents, vinca-alkaloids, and other.

RESULTS

The overall median heart volume reduction from the first to the last CBCT was 5.5% (interquartile range1.6-9.7%; p < 0.001). Heart volumes decreased significantly between the baseline measurement and the first week (Bonferroni's adjusted p = 0.002); volume changes were not significant during the following weeks. Univariate analysis showed a significant correlation between heart volume reduction and alkylating agents; however, no multivariate analyses could be done to further confirm this.

CONCLUSIONS

We found a significant heart volume reduction in children during radiotherapy. Elucidation of underlying mechanisms, clinical relevance, and possible long-term consequences of early heart volume reduction require a prospective follow-up study.

Associations Between Ambient Particle Radioactivity and Blood Pressure: The NAS (Normative Aging Study)

BACKGROUND

The cardiovascular effects of low-level environmental radiation exposures are poorly understood. Although particulate matter (PM) has been linked to cardiovascular morbidity and mortality, and elevated blood pressure (BP), the properties promoting its toxicity remain uncertain. Addressing a knowledge gap, we evaluated whether BP increased with higher exposures to radioactive components of ambient PM, herein referred to as particle radioactivity (PR).

METHODS AND RESULTS

We performed a repeated-measures analysis of 852 men to examine associations between PR exposure and BP using mixed-effects regression models. As a surrogate for PR, we used gross β activity, measured by the US Environmental Protection Agency's radiation monitoring network. Higher PR exposure was associated with increases in both diastolic BP and systolic BP, for exposures from 1 to 28 days. An interquartile range increase in 28-day PR exposure was associated with a 2.95-mm Hg increase in diastolic BP (95% confidence interval, 2.25-3.66; P<0.001) and a 3.94-mm Hg increase in systolic BP (95% confidence interval, 2.62-5.27; P<0.001). For models including both PR and PM ≤2.5 µm, the PR-BP associations remained stable and significant. For models including PR and black carbon or PR and particle number, the PR-BP associations were attenuated; however, they remained significant for many exposure durations.

CONCLUSIONS

This is the first study to demonstrate the potential adverse effects of PR on both systolic and diastolic BPs. These were independent and similar in magnitude to those of PM ≤2.5 µm, black carbon, and particle number. Understanding the effects of particle-bound radionuclide exposures on BP may have important implications for environmental and public health policy.

Gamma Low-Dose-Rate Ionizing Radiation Stimulates Adaptive Functional and Molecular Response in Human Aortic Endothelial Cells in a Threshold-, Dose-, and Dose Rate-Dependent Manner

A central question in radiation protection research is whether low-dose and low-dose-rate (LDR) exposures to ionizing radiation play a role in progression of cardiovascular disease. The response of endothelial cells to different LDR exposures may help estimate risk of cardiovascular disease by providing the biological mechanism involved. We investigated the effect of chronic LDR radiation on functional and molecular responses of human aorta endothelial cells (HAoECs). Human aorta endothelial cells were continuously irradiated at LDR (6 mGy/h) for 15 days and analyzed at time points when the cumulative dose reached 0.05, 0.5, 1.0, and 2.0 Gy. The same doses were administered acutely at high-dose rate (HDR; 1 Gy/min). The threshold for the loss of angiogenic capacity for both LDR and HDR radiations was between 0.5 and 1.0 Gy. At 2.0 Gy, angiogenic capacity returned to normal only for HAoEC exposed to LDR radiation, associated with increased expression of antioxidant and anti-inflammatory genes. Pre-LDR, but not pre-HDR, radiation, followed by a single acute 2.0 Gy challenge dose sustained the expression of antioxidant and anti-inflammatory genes and stimulated angiogenesis. Our results suggest that dose rate is important in cellular response and that a radioadaptive response is involved for a 2.0 Gy dose at LDR.

Severe bilateral isolated coronary ostial lesions as a rare manifestation of radiation-induced cardiac disease A case report

RATIONALE

With advances in contemporary radiotherapy techniques, and as cancer survival improves, severe isolated coronary ostial disease may develop many years following mediastinal radiotherapy, even in the absence of classical cardiovascular risk factors.

PATIENT CONCERNS

We describe the case of a 73-year-old woman with previous chest radiotherapy for breast cancer who underwent coronary artery bypass graft surgery for severe bilateral coronary ostial lesions.

DIAGNOSES

Coronary angiography demonstrated severe, isolated bilateral coronary ostial lesions.

INTERVENTIONS

The patient underwent urgent coronary artery bypass graft surgery to treat her critical coronary artery disease.

OUTCOMES

Intra-operatively, internal mammary arteries were not amenable to harvesting due to very dense mediastinal adhesions. Therefore, saphenous vein grafts were performed to the left anterior descending, distal left circumflex, obtuse marginal and distal right coronary arteries. The patient made a satisfactory in-hospital recovery, and was subsequently discharged back to her local hospital for rehabilitation.

LESSONS

Patients successfully treated with mediastinal radiotherapy require careful long-term follow-up for the assessment of radiation-induced coronary artery disease. Importantly, mediastinal irradiation may preclude internal mammary artery utilization, and thus alter the strategy for surgical myocardial revascularization.

Risk of Coronary Events 55 Years after Thymic Irradiation in the Hempelmann Cohort

Background

Studies of cancer survivors treated with older radiotherapy (RT) techniques (pre-1990s) strongly suggest that ionizing radiation to the chest increases the risk of coronary heart disease (CHD). Our goal was to evaluate the impact of more modern cardiac shielding techniques of RT on the magnitude and timing of CHD risk by studying a cohort exposed to similar levels of cardiac irradiation years ago.

Methods

Between 2004 and 2008, we re-established a population-based, longitudinal cohort of 2657 subjects exposed to irradiation for an enlarged thymus during infancy between 1926 and 1957 and 4388 of their non-irradiated siblings. CHD events were assessed using a mailed survey and from causes of death listed in the National Death Index. We used Poisson regression methods to compare incidence rates by irradiation status and cardiac radiation dose. Results were adjusted for the CHD risk factors of attained-age, sex, diabetes, dyslipidemia hypertension and smoking.

Results

Median age at time of follow-up was 57.5 years (range 41.2–88.8 yrs) for irradiated and non-irradiated siblings. The mean estimated cardiac dose amongst the irradiated was 1.45 Gray (range 0.17–20.20 Gy), with 91% receiving < 3.00 Gy. During a combined 339,924 person-years of follow-up, 213 myocardial infarctions (MI) and 350 CHD events (MI, bypass surgery and angioplasty) occurred. After adjustment for attained age, gender, and other CHD risk factors, the rate ratio for MI incidence in the irradiated group was 0.98 (95%CI, 0.74–1.30), and for any CHD event was 1.07 (95%CI, 0.86–1.32). Higher radiation doses were not associated with more MIs or CHD events in this dose range, in either the crude or the adjusted analyses.

Conclusions

Radiation to the heart during childhood of < 3 Gy, the exposure in most of our cohort, does not increase the lifelong risk of CHD. Reducing cardiac radiation to this amount without increasing other cardiotoxic therapies may eliminate the increased CHD risk associated with radiotherapy for childhood cancer. By extension there is unlikely to be increased CHD risk from relatively higher dose imaging techniques, such as CT, because such techniques use much smaller radiation doses than received by our cohort.

Radiation-Induced Coronary Artery Disease in Young Patients

Exposure to radiotherapy has been shown to accelerate myocardial damage or injury to the cardiac vasculature. Accelerated coronary artery disease (CAD) is one of the main manifestations of cardiac disease in patients who undergo mediastinal radiation therapy. We present the cases of three young patients who developed severe CAD secondary to remote mediastinal radiotherapy.

Optical metabolic imaging of irradiated rat heart exposed to ischemia-reperfusion injury

Whole thoracic irradiation (WTI) is known to cause deterioration in cardiac function. Whether irradiation predisposes the heart to further ischemia and reperfusion (IR) injury is not well known. The aim of this study is to examine the susceptibility of rat hearts to IR injury following a single fraction of 15 Gy WTI and to investigate the role of mitochondrial metabolism in the differential susceptibility to IR injury. After day 35 of irradiation, ex vivo hearts from irradiated and nonirradiated rats (controls) were exposed to 25-min global ischemia followed by 60-min IR, or hearts were perfused without IR for the same protocol duration [time controls (TC)]. Online fluorometry of metabolic indices [redox state: reduced nicotinamide adenine dinucleotide (NADH), oxidized flavin adenine dinucleotide (FAD), and NADH/FAD redox ratio] and functional variables [systolic left ventricular pressure (LVP), diastolic LVP (diaLVP), coronary flow (CF), and heart rate were recorded in the beating heart; developed LVP (dLVP) and rate pressure product (RPP)] were derived. At the end of each experimental protocol, hearts were immediately snap frozen in liquid N2 for later three-dimensional imaging of the mitochondrial redox state using optical cryoimaging. Irradiation caused a delay in recovery of dLVP and RPP after IR when compared to nonirradiated hearts but recovered to the same level at the end of reperfusion. CF in the irradiated hearts recovered better than the control hearts after IR injury. Both fluorometry and 3-D cryoimaging showed that in WTI and control hearts, the redox ratio increased during ischemia (reduced) and decreased on reperfusion (oxidized) when compared to their respective TCs; however, there was no significant difference in the redox state between WTI and controls. In conclusion, our results show that although irradiation of rat hearts compromised baseline cardiovascular function, it did not alter cardiac mitochondrial redox state and induce greater susceptibility of these hearts to IR injury.

Prophylactic use of colchicine in preventing radiation induced coronary artery disease

Radiation therapy is one of the primary treatments in fighting breast cancer, one of the most common cancers in the US. One of the dose limiting factors of this therapy is radiation induced heart damage that results from mediastinal radiation. Recently statins, a medication typically used to lower cholesterol levels, have been suggested as a prophylactic treatment to potentially mitigate this process. Similarly, we hypothesized whether colchicine, an anti-inflammatory medication that is presently used in the treatment of gout and pericarditis, might be used to prevent coronary artery disease induced by radiation therapy. We hypothesize that colchicine may help prevent the deleterious effect on coronary arteries induced by radiation therapy by inhibiting inflammation and platelet aggregation. The pathophysiology of radiation induced coronary artery disease is similar to that of coronary artery disease in the general population. Inflammation, fibrosis and platelet aggregation play a key role in this process. After radiation therapy, inflammation occurs, recruiting leukocytes, particularly neutrophils and monocytes. Neutrophils are fibrotic mediators, and macrophages form foam cells in the intimal layer of the vessel wall, leading to the build-up of atherosclerotic plaques. Platelet aggregation, both initially and upon plaque rupture, is also a culprit in exacerbating radiation damage. Colchicine is known to inhibit microtubule polymerization and therefore inhibits mitosis, neutrophil motility and has been shown to decrease platelet aggregation. Its anti-inflammatory properties have been attributed to several different effects based on microtubule dysfunction. Colchicine has also been shown to affect the expression of adhesion molecules on endothelial cells, leukocytes, and to decrease activation of thrombin induced platelet aggregation. There is evidence to suggest that colchicine may be beneficial in the treatment of radiation induced coronary artery disease due to its anti-inflammatory and anti-coagulant properties. This idea would be beneficial for future studies.

Out of the frying pan and into the fire: damage-associated molecular patterns and cardiovascular toxicity following cancer therapy

Cardio-oncology is a new and rapidly expanding field that merges cancer and cardiovascular disease. Cardiovascular disease is an omnipresent side effect of cancer therapy; in fact, it is the second leading cause of death in cancer survivors after recurrent cancer. It has been well documented that many cancer chemotherapeutic agents cause cardiovascular toxicity. Nonetheless, the underlying cause of cancer therapy-induced cardiovascular toxicity is largely unknown. In this review, we discuss the potential role of damage-associated molecular patterns (DAMPs) as an underlying contributor to cancer therapy-induced cardiovascular toxicity. With an increasing number of cancer patients, as well as extended life expectancy, understanding the mechanisms underlying cancer therapy-induced cardiovascular disease is of the utmost importance to ensure that cancer is the only disease burden that cancer survivors have to endure.

Mechanisms driving the ageing heart

Cardiovascular disease (CVD) is the leading cause of death globally. One of the main risk factors for CVD is age, however the biological processes that occur in the heart during ageing are poorly understood. It is therefore important to understand the fundamental mechanisms driving heart ageing to enable the development of preventions and treatments targeting these processes. Cellular senescence is often described as the irreversible cell-cycle arrest which occurs in somatic cells. Emerging evidence suggests that cellular senescence plays a key role in heart ageing, however the cell-types involved and the underlying mechanisms are not yet elucidated. In this review we discuss the current understanding of how mechanisms known to contribute to senescence impact on heart ageing and CVD. Finally, we evaluate recent data suggesting that targeting senescent cells may be a viable therapy to counteract the ageing of the heart.

Proteomics landscape of radiation-induced cardiovascular disease: somewhere over the paradigm

INTRODUCTION

Epidemiological studies clearly show that thoracic or whole body exposure to ionizing radiation increases the risk of cardiac morbidity and mortality. Radiation-induced cardiovascular disease (CVD) has been intensively studied during the last ten years but the underlying molecular mechanisms are still poorly understood. Areas covered: Heart proteomics is a powerful tool holding promise for the future research. The central focus of this review is to compare proteomics data on radiation-induced CVD with data arising from proteomics of healthy and diseased cardiac tissue in general. In this context we highlight common and unique features of radiation-related and other heart pathologies. Future prospects and challenges of the field are discussed. Expert commentary: Data from comprehensive cardiac proteomics have deepened the knowledge of molecular mechanisms involved in radiation-induced cardiac dysfunction. State-of-the-art proteomics has the potential to identify novel diagnostic and therapeutic markers of this disease.

Impact of Ionizing Radiation on the Cardiovascular System: A Review

Radiation therapy has become one of the main forms of treatment for various types of cancers. Cancer patients previously treated with high doses of radiation are at a greater risk to develop cardiovascular complications later in life. The heart can receive varying doses of radiation depending on the type of therapy and can even reach doses in the range of 17 Gy. Multiple studies have highlighted the role of oxidative stress and inflammation in radiation-induced cardiovascular damage. Doses of ionizing radiation below 200 mGy, however, have been shown to have beneficial effects in some experimental models of radiation-induced damage, but low-dose effects in the heart is still debated. Low-dose radiation may promote heart health and reduce damage from oxidative stress and inflammation, however there are few studies focusing on the impact of low-dose radiation on the heart. In this review, we summarize recent studies from animal models and human data focusing on the effects and mechanism(s) of action of radiation-induced damage to the heart, as well as the effects of high and low doses of radiation and dose rates.

Extensive pericardial calcification secondary to radiotherapy, causing mixed constrictive-restrictive pathology

This report presents the case of a patient who suffered from a mediastinal neuroblastoma in his childhood (in 1977), having been treated by surgery, chemotherapy and radiotherapy. As a result, he developed multiple calcifications in the atria walls, interatrial septum, right ventricular free wall, mitral and aortic valves and pericardium, triggering a mixed constrictive and restrictive pathology.

Potential markers and metabolic processes involved in the mechanism of radiation-induced heart injury

Irradiation of normal tissues leads to acute increase in reactive oxygen/nitrogen species that serve as intra- and inter-cellular signaling to alter cell and tissue function. In the case of chest irradiation, it can affect the heart, blood vessels, and lungs, with consequent tissue remodelation and adverse side effects and symptoms. This complex process is orchestrated by a large number of interacting molecular signals, including cytokines, chemokines, and growth factors. Inflammation, endothelial cell dysfunction, thrombogenesis, organ dysfunction, and ultimate failing of the heart occur as a pathological entity - "radiation-induced heart disease" (RIHD) that is major source of morbidity and mortality. The purpose of this review is to bring insights into the basic mechanisms of RIHD that may lead to the identification of targets for intervention in the radiotherapy side effect. Studies of authors also provide knowledge about how to select targeted drugs or biological molecules to modify the progression of radiation damage in the heart. New prospective studies are needed to validate that assessed factors and changes are useful as early markers of cardiac damage.

Effects of low-dose rate γ-irradiation combined with simulated microgravity on markers of oxidative stress, DNA methylation potential, and remodeling in the mouse heart

Purpose

Space travel is associated with an exposure to low-dose rate ionizing radiation and the microgravity environment, both of which may lead to impairments in cardiac function. We used a mouse model to determine short- and long-term cardiac effects to simulated microgravity (hindlimb unloading; HU), continuous low-dose rate γ-irradiation, or a combination of HU and low-dose rate γ-irradiation.

Methods

Cardiac tissue was obtained from female, C57BL/6J mice 7 days, 1 month, 4 months, and 9 months following the completion of a 21 day exposure to HU or a 21 day exposure to low-dose rate γ-irradiation (average dose rate of 0.01 cGy/h to a total of 0.04 Gy), or a 21 day simultaneous exposure to HU and low-dose rate γ-irradiation. Immunoblot analysis, rt-PCR, high-performance liquid chromatography, and histology were used to assess inflammatory cell infiltration, cardiac remodeling, oxidative stress, and the methylation potential of cardiac tissue in 3 to 6 animals per group.

Results

The combination of HU and γ-irradiation demonstrated the strongest increase in reduced to oxidized glutathione ratios 7 days and 1 month after treatment, but a difference was no longer apparent after 9 months. On the other hand, no significant changes in 4-hydroxynonenal adducts was seen in any of the groups, at the measured endpoints. While manganese superoxide dismutase protein levels decreased 9 months after low-dose γ-radiation, no changes were observed in expression of catalase or Nrf2, a transcription factor that determines the expression of several antioxidant enzymes, at the measured endpoints. Inflammatory marker, CD-2 protein content was significantly decreased in all groups 4 months after treatment. No significant differences were observed in α-smooth muscle cell actin protein content, collagen type III protein content or % total collagen.

Conclusions

This study has provided the first and relatively broad analysis of small molecule and protein markers of oxidative stress, T-lymphocyte infiltration, and cardiac remodeling in response to HU with simultaneous exposure to low-dose rate γ-radiation. Results from the late observation time points suggest that the hearts had mostly recovered from these two experimental conditions. However, further research is needed with larger numbers of animals for a more robust statistical power to fully characterize the early and late effects of simulated microgravity combined with exposure to low-dose rate ionizing radiation on the heart.

Cardio-oncology: cardiovascular complications of cancer therapy

This paper focuses on three classes of commonly used anticancer drugs, which can cause cardiotoxicity: anthracyclines, monoclonal antibodies exemplified by trastuzumab and tyrosine kinase inhibitors. Anthracyclines can induce cardiomyocyte necrosis and fibrosis. Trastuzumab can cause cardiac stunning. The tyrosine kinase inhibitors can increase systemic arterial pressure and impair myocyte contractility. In addition, radiation therapy to the mediastinum or left chest can exacerbate the cardiotoxicity of these anticancer drugs and can also cause accelerated atherosclerosis, myocardial infarction, heart failure and arrhythmias. Left ventricular ejection fraction measurements are most commonly used to assess cardiac function in patients who receive chemo- or radiation-therapy. However, echocardiographic determinations of global longitudinal strain are more sensitive for detection of early left ventricular systolic dysfunction. Information on patient-risk stratification and monitoring is presented and guidelines for the medical treatment of cardiac dysfunction due to cancer therapies are summarized.