Heart disease following radiation

Cardiotoxicity following thoracic radiotherapy for lung cancer

Radiotherapy is the standard of care treatment for unresectable NSCLC, combined with concurrent chemotherapy and adjuvant immunotherapy. Despite technological advances in radiotherapy planning and delivery, the risk of damage to surrounding thoracic tissues remains high. Cardiac problems, including arrhythmia, heart failure and ischaemic events, occur in 20% of patients with lung cancer who undergo radiotherapy. As survival rates improve incrementally for this cohort, minimising the cardiovascular morbidity of RT is increasingly important. Problematically, the reporting of cardiac endpoints has been poor in thoracic radiotherapy clinical trials, and retrospective studies have been limited by the lack of standardisation of nomenclature and endpoints. How baseline cardiovascular profile and cardiac substructure radiation dose distribution impact the risk of cardiotoxicity is incompletely understood. As Thoracic Oncology departments seek to expand the indications for radiotherapy, and as the patient cohort becomes older and more comorbid, there is a pressing need for cardiotoxicity to be comprehensively characterised with sophisticated oncology, physics and cardio-oncology evaluations. This review synthesises the evidence base for cardiotoxicity in conventional radiotherapy, focusing on lung cancer, including current data, unmet clinical needs, and future scientific directions.

Mediastinal irradiation and valvular heart disease

Anticancer therapy has the potential to cause unwanted cardiovascular side effects. Utilization of radiation therapy to treat tumors near the heart can result in radiation-induced valvular heart disease among other cardiovascular pathologies. The aim of this review is to describe the epidemiology, pathophysiology, risk prediction, non-invasive imaging modalities and management of radiation-induced valvular heart disease with a focus on pre-operative risk assessment and contemporary treatment options.

Puerarin Reduces Radiation-Induced Vascular Endothelial Cell Damage Via miR-34a/Placental Growth Factor

The aim is to explore the protective effects of Puerarin on radiation-induced vascular endothelial cell damage and its underlying mechanism. The apoptosis and DNA damage of Human umbilical vascular endothelial cells (HUVECs) exposed to radiation alone or in combination with glucose in the exposed group were significantly elevated (P < .05) compared with those in the control group. The Puerarin-treated HUVECs showed significant reduction in the radiation-induced apoptosis and DNA damage (P < .05). Furthermore, X-ray irradiation significantly increased the expression of miR-34a, which was reversed by pre-treatment with Puerarin. Placental Growth Factor (PLGF) was a target gene of miR-34a. The expression of PLGF in the peripheral blood of patients receiving radiotherapy significantly increased with an increase in the cumulative dose of radiation (P < .05), after which it began to decrease at the fourth week (P < .05) and then remained at a low level until the end of radiotherapy. Puerarin exerts a radioprotective effect by decreasing DNA damage and apoptosis through miR-34a-targeted PLGF.

Cardiotoxicity in pediatric lymphoma survivors

INTRODUCTION

Over the past five decades, the diagnosis and management of children with various malignancies have improved tremendously. As a result, an increasing number of children are long-term cancer survivors. With improved survival, however, has come an increased risk of treatment-related cardiovascular complications that can appear decades later.

AREAS COVERED

This review discusses the pathophysiology, epidemiology and effects of treatment-related cardiovascular complications from anthracyclines and radiotherapy in pediatric lymphoma survivors. There is a paucity of evidence-based recommendations for screening for and treatment of cancer therapy-induced cardiovascular complications. We discuss current preventive measures and strategies for their treatment.

EXPERT OPINION

Significant cardiac adverse effects occur due to radiation and chemotherapy received by patients treated for lymphoma. Higher lifetime cumulative doses, female sex, longer follow-up, younger age, and preexisting cardiovascular disease are associated with a higher incidence of cardiotoxicity. With deeper understanding of the mechanisms of these adverse cardiac effects and identification of driver mutations causing these effects, personalized cancer therapy to limit cardiotoxic effects while ensuring an adequate anti-neoplastic effect would be ideal. In the meantime, expanding the use of cardioprotective agents with the best evidence such as dexrazoxane should be encouraged and further studied.

Mesenchymal stem cell-derived extracellular vesicles as probable triggers of radiation-induced heart disease

BACKGROUND

Radiation-induced heart disease has been reported, but the underlying mechanisms remain unclear. Mesenchymal stem cells (MSCs), also residing in the heart, are highly susceptible to radiation. We examined the hypothesis that the altered secretion of extracellular vesicles (EVs) from MSCs is the trigger of radiation-induced heart disease.

METHODS

By exposing human placental tissue-derived MSCs to 5 Gy γ-rays, we then isolated EVs from the culture medium 48 h later and evaluated the changes in quantity and quality of EVs from MSCs after radiation exposure. The biological effects of EVs from irradiated MSCs on HUVECs and H9c2 cells were also examined.

RESULTS

Although the amount and size distribution of EVs did not differ between the nonirradiated and irradiated MSCs, miRNA sequences indicated many upregulated or downregulated miRNAs in irradiated MSCs EVs. In vitro experiments using HUVEC and H9c2 cells showed that irradiated MSC-EVs decreased cell proliferation (P < 0.01), but increased cell apoptosis and DNA damage. Moreover, irradiated MSC-EVs impaired the HUVEC tube formation and induced calcium overload in H9c2 cells.

CONCLUSIONS

EVs released from irradiated MSCs show altered miRNA profiles and harmful effects on heart cells, which provides new insight into the mechanism of radiation-related heart disease risks.

Impairment of IGF-1 Signaling and Antioxidant Response Are Associated with Radiation Sensitivity and Mortality

Following exposure to high doses of ionizing radiation, diverse strains of vertebrate species will manifest varying levels of radiation sensitivity. To understand the inter-strain cellular and molecular mechanisms of radiation sensitivity, two mouse strains with varying radiosensitivity (C3H/HeN, and CD2F1), were exposed to total body irradiation (TBI). Since Insulin-like Growth Factor-1 (IGF-1) signaling pathway is associated with radiosensitivity, we investigated the link between systemic or tissue-specific IGF-1 signaling and radiosensitivity. Adult male C3H/HeN and CD2F1 mice were irradiated using gamma photons at Lethal Dose-70/30 (LD_70/30), 7.8 and 9.35 Gy doses, respectively. Those mice that survived up to 30 days post-irradiation, were termed the survivors. Mice that were euthanized prior to 30 days post-irradiation due to deteriorated health were termed decedents. The analysis of non-irradiated and irradiated survivor and decedent mice showed that inter-strain radiosensitivity and post-irradiation survival outcomes are associated with activation status of tissue and systemic IGF-1 signaling, nuclear factor erythroid 2-related factor 2 (Nrf2) activation, and the gene expression profile of cardiac mitochondrial energy metabolism pathways. Our findings link radiosensitivity with dysregulation of IGF-1 signaling, and highlight the role of antioxidant gene response and mitochondrial function in radiation sensitivity.

The use of cardiovascular magnetic resonance as an early non-invasive biomarker for cardiotoxicity in cardio-oncology

Contemporary cancer therapy has resulted in significant survival gains for patients. However, many current and emerging cancer therapies have an associated risk of cardiotoxicity, either acutely or later in life. Regular cardiac screening and surveillance is recommended for patients undergoing treatment for cancer, with emphasis on the early detection of cardiotoxicity before irreversible complications develop. Cardiovascular magnetic resonance imaging is able to accurately assess cardiac structure, function, and perform advanced myocardial tissue characterisation, including perfusion, features which may facilitate the diagnosis and management of cardiotoxicity in cancer survivors. This review outlines the current standards for the diagnosis and screening of cardiotoxicity, with particular focus on current and future applications of cardiovascular magnetic resonance imaging.

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.

Coronary Artery Stenosis following Mediastinal Radiation Therapy. Case Report and Review of the Literature

A case of coronary artery stenosis following mediastinal radiation therapy in a young woman and a review of the literature offer indications on the criteria to follow in the diagnosis of coronary artery disease secondary to mediastinal radiation therapy.

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.

Long-term cardiovascular health in adult cancer survivors

The number of cancer survivors has tremendously increased over the past decades as a result of aging of the population and improvements in early cancer detection and treatment. Ongoing successes in cancer treatment are expected to result in a further increase in the number of long-term survivors. However, cancer treatment can have detrimental cardiovascular side-effects that impact morbidity and mortality, reducing quality of life in cancer survivors. The spectrum of radiotherapy- and chemotherapy-induced cardiovascular disease is broad, varying from subclinical valvular dysfunction to overt congestive heart failure, and such effects may not be apparent for more than twenty years after the initial cancer treatment. Awareness of these long-term side-effects is of crucial value in the management of these patients, in order to reduce the impact of cardiovascular morbidity and mortality. This review provides a comprehensive overview of the long-term cardiovascular complications of cancer treatments (radiotherapy and chemotherapy) in adult cancer survivors.

Radiation-induced heart disease: an under-recognized entity?

OPINION STATEMENT

Radiation-induced heart disease (RIHD) represents a spectrum of cardiovascular disease in patients who have undergone mediastinal, thoracic, or breast radiotherapy (RT). RIHD may involve any cardiac structure and is a major cause of morbidity and mortality in cancer survivors. While large cohort studies have demonstrated that symptomatic RIHD is a common late finding in this population, the incidence of asymptomatic disease is likely to be even higher. Long-term follow-up with regular screening for RIHD plays an important role in the management of cancer survivors who have undergone RT. Aggressive modification of traditional cardiovascular risk factors such as hypertension, dyslipidemia, and cigarette smoking is essential in patients at risk for RIHD, as these have been shown to potentiate the risks of radiation. In patients with symptomatic RIHD, medical and/or percutaneous therapies are often preferable to surgical interventions in view of the increased surgical risk associated with radiation damage to surrounding tissues. Percutaneous revascularization should generally be favored over surgical revascularization. Transcatheter valve replacements have not been widely used in this population but may offer an alternative to high-risk surgical valve procedures. Pericardiectomy is usually associated with extremely poor short-term and long-term outcomes in patients with RIHD and should be avoided in most cases. Heart transplantation is also higher risk in patients with RIHD than in patients with other etiologies of heart failure, but may be considered in young patients without other comorbidities.

Cardiovascular complications of radiotherapy

Chest radiotherapy is routinely used to treat malignancies such as Hodgkin disease and breast cancer but is commonly associated with a variety of cardiovascular complications involving the pericardium, myocardium, valves, coronary arteries, and conduction system. Cardiovascular complications are related to the total dose of radiation and the fractionation of the dose. They are usually progressive, portend poor prognosis, and are often refractory to treatment after significant radiation exposure. The mechanism of injury is multifactorial and likely involves endothelial damage of the microvasculature and coronary arteries and liberation of multiple inflammatory and profibrotic cytokines. In conclusion, routine follow-up with a cardiologist, which might include screening for valvular disease with echocardiography and coronary artery disease with computed tomography angiography or coronary artery calcium scoring, should be considered in patients with a history of chest radiotherapy.

Complications of thoracic radiotherapy

The issue of toxicity is a primary concern for chest irradiation, because it is a dose-limiting toxicity and because in some circumstances it can alleviate the survival benefit of radiation therapy. Potential acute and delayed side effects can compromise the patients' prognosis and generate significant morbidity. Here we review on chest complications of radiation therapy, with focus on cardiac and pulmonary radio-induced side effects. Most radiographic changes associated with thoracic irradiation are asymptomatic. However, chest irradiation generated by treatment of breast cancer, bronchopulmonary malignancies, or mediastinal lymphoma has been associated with a risk of acute radiation pneumonitis and late lung fibrosis. An increasing number of clinical studies suggest that some dosimetric factors (e.g. V20, V30, mean lung dose) should be considered for limiting the risk of lung toxicity. Improvements in radiation techniques as well as changes in indications, volumes and prescribed doses of radiation therapy should help to better spare lungs from irradiation and thus decreasing the risk of subsequent toxicity. Numerous other contributing factors should also be considered, such as chemotherapeutic agents, smoking, tumor topography, or intrinsic sensitivity. Cardiac toxicity is another clinically relevant issue in patients receiving radiation therapy for breast cancer or for lymphoma. This life threatening toxicity should be analyzed in the light of dosimetric factors (including low doses) but also associated systemic agents which almost carry a potential for additive toxicity toward myocardium or coronaries. A long-term follow-up of patients as well as an increasing knowledge of the underlying biological pathways involved in cardiac toxicity should help designing effective preventing strategies.

Cardiovascular complications of radiation therapy for thoracic malignancies: the role for non-invasive imaging for detection of cardiovascular disease

Radiation exposure to the thorax is associated with substantial risk for the subsequent development of cardiovascular disease. Thus, the increasing role of radiation therapy in the contemporary treatment of cancer, combined with improving survival rates of patients undergoing this therapy, contributes to a growing population at risk of cardiovascular morbidity and mortality. Associated cardiovascular injuries include pericardial disease, coronary artery disease, valvular disease, conduction disease, cardiomyopathy, and medium and large vessel vasculopathy-any of which can occur at varying intervals following irradiation. Higher radiation doses, younger age at the time of irradiation, longer intervals from the time of radiation, and coexisting cardiovascular risk factors all predispose to these injuries. The true incidence of radiation-related cardiovascular disease remains uncertain due to lack of large multicentre studies with a sufficient duration of cardiovascular follow-up. There are currently no consensus guidelines available to inform the optimal approach to cardiovascular surveillance of recipients of thoracic radiation. Therefore, we review the cardiovascular consequences of radiation therapy and focus on the potential role of non-invasive cardiovascular imaging in the assessment and management of radiation-related cardiovascular disease. In doing so, we highlight characteristics that can be used to identify individuals at risk for developing post-radiation cardiovascular disease and propose an imaging-based algorithm for their clinical surveillance.

Radiation-induced heart disease

Radiation-induced heart disease (RIHD) is becoming an increasing concern for patients and clinicians alike as the use of radiation therapy for the treatment of certain malignancies increases, and patient mortality secondary to neoplasms of the thorax, in particular Hodgkin's lymphoma and breast cancer, decreases. The spectrum of pathology affecting the heart spans from acute to chronic and can affect almost all facets of the heart, including but not restricted to the pericardial sac, coronary arteries, myocardium, and heart valves. Significant research has been conducted over the past 40 years to further understand the toxic effects of radiation therapy and those protective methods that could curtail these adverse reactions. This article will focus on RIHD, the pathophysiological mechanisms for RIHD, the clinical presentations, and current and future directions for attempting to reduce the incidence of this condition.

Irradiation induced modest changes in murine cardiac function despite progressive structural damage to the myocardium and microvasculature

BACKGROUND

Radiotherapy of thoracic and chest wall tumors increases the long-term risk of cardiotoxicity, but the underlying mechanisms are unclear.

METHODS

Single doses of 2, 8, or 16 Gy were delivered to the hearts of mice and damage was evaluated at 20, 40, and 60 weeks, relative to age matched controls. Single photon emission computed tomography (SPECT/CT) and ultrasound were used to measure cardiac geometry and function, which was related to histo-morphology and microvascular damage.

RESULTS

Gated SPECT/CT and ultrasound demonstrated decreases in end diastolic and systolic volumes, while the ejection fraction was increased at 20 and 40 weeks after 2, 8, and 16 Gy. Cardiac blood volume was decreased at 20 and 60 weeks after irradiation. Histological examination revealed inflammatory changes at 20 and 40 weeks after 8 and 16 Gy. Microvascular density in the left ventricle was decreased at 40 and 60 weeks after 8 and 16 Gy, with functional damage to remaining microvasculature manifest as decreased alkaline phosphatase (2, 8, and 16 Gy), increased von Willebrand Factor and albumin leakage from vessels (8 and 16 Gy), and amyloidosis (16 Gy). 16 Gy lead to sudden death between 30 and 40 weeks in 38% of mice.

CONCLUSIONS

Irradiation with 2 and 8 Gy induced modest changes in murine cardiac function within 20 weeks but this did not deteriorate further, despite progressive structural and microvascular damage. This indicates that heart function can compensate for significant structural damage, although higher doses, eventually lead to sudden death.

Radiation as a risk factor for cardiovascular disease

Abstract population are ubiquitous background radiation and medical exposure of patients. From the early 1980s to 2006, the average dose per individual in the United States for all sources of radiation increased by a factor of 1.7-6.2 mSv, with this increase due to the growth of medical imaging procedures. Radiation can place individuals at an increased risk of developing cardiovascular disease. Excess risk of cardiovascular disease occurs a long time after exposure to lower doses of radiation as demonstrated in Japanese atomic bomb survivors. This review examines sources of radiation (atomic bombs, radiation accidents, radiological terrorism, cancer treatment, space exploration, radiosurgery for cardiac arrhythmia, and computed tomography) and the risk for developing cardiovascular disease. The evidence presented suggests an association between cardiovascular disease and exposure to low-to-moderate levels of radiation, as well as the well-known association at high doses. Studies are needed to define the extent that diagnostic and therapeutic radiation results in increased risk factors for cardiovascular disease, to understand the mechanisms involved, and to develop strategies to mitigate or treat radiation-induced cardiovascular disease.

Coronary heart disease--a possible risk in megavoltage therapy?

A 21-year old man died of an extensive anteroseptal myocardial infarction 16 months after receiving megavoltage radiotherapy to a mantle field for Hodgkin's disease stage PS IA confined to the midcervical lymph nodes on the left side of the neck. Post mortem findings revealed severe atherosclerotic changes in the coronary arteries. This case and a review of the literature suggest that irradiation to the heart may induce or accelerate atherosclerosis of the epicardial vessels. This should be taken into consideration when starting prophylactic irradiation to the mantle field in patients with Hodgkin's disease stage IA without obvious involvement of the mediastinun. Histologic examination of the heart and coronary vessels should be performed in any fatal case after megavoltage therapy involving the heart.

Cardiocutaneous fistula in a delayed iathrogenic ventricular perforation of the heart: computed tomographic and magnetic resonance imaging findings

Cardiac iathrogenic lesions can occur during diagnostic or therapeutic procedures. Resistance of the heart to an injury may cause a delay from the traumatic event to onset of the symptomatology or to heart rupture. We describe a rare case cardiac perforation with delayed rupture of the heart in a patient previously submitted to radiation therapy for breast cancer. Cardiocutaneous fistula at the cross-sectional computed tomographic and magnetic resonance imaging findings has not been previously reported, to our knowledge.

Radiation pericarditis and breast reconstruction: a surgical dilemma

OBJECTIVE

To discuss a case of radiation pericarditis and the physiology of the disease, and to discuss the left thoracotomy as an effective alternative to median sternotomy for pericardiectomy in the treatment of complicated radiation pericarditis.

DESIGN

A case report with accompanying discussion of the disease and literature search.

SETTING

Keesler Air Force Base Medical Center, a military training facility and general surgery residency program.

PARTICIPANTS

A single case report with review of literature.

RESULTS

Left thoracotomy is an effective alternative to median sternotomy for the surgical treatment of radiation pericarditis, with a mild increase in pulmonary-associated complications.

CONCLUSIONS

With an increase in the use of mediastinal radiation for treatment of malignant disease as well as the increase in women having reconstructive procedures of the breast, one may expect complicated cases of radiation pericarditis that may not be amenable to median sternotomy. Left thoracotomy may be an alternative to median sternotomy for pericardiectomy in cases of pericarditis complicated by cosmetic constraints.

Dose mapping of porcine coronary arteries using an optical fiber dosimeter

BACKGROUND

This study is about the measurement of radiation dose contribution to the coronary arteries during intravascular brachytherapy with beta and gamma emitters utilizing in vivo optical fiber dosimeters.

METHODS AND MATERIALS

Domestic pigs were used. With each measurement, catheters were introduced into two different coronary arteries, including the left circumflex (LCX), the left anterior descending (LAD), the first diagonal, and/or the right coronary artery (RCA). A radioactive source (192Ir, 90Sr/Y, or 32P) and the dosimeter were loaded in each of these catheters. Data were collected as the dosimeter was being retracted at a constant rate via computer control.

RESULTS

The radiation dose was normalized to 100% at a 2-mm radial distance from the source. When radiating a branching artery, the dose to the bifurcation at 5 mm from the source was 35%, 10%, and 3% for the 192Ir (10 seeds), 90Sr/Y (40 mm), and 32P sources, respectively. When utilizing a 23-seed 192Ir source, the dose is 40% at a 5-mm distance. However, radiation of the RCA did not result in dosing to the LAD or LCX using any source.

CONCLUSIONS

The dose to adjacent artery segments is less with beta than with gamma emitters. Significant dose exposition is noted when using gamma emitters at a distance of 5 mm. The results can serve as a guideline for establishing prescription doses and safety margins for the treatment of bifurcation lesions and retreatment of the arteries.

Noncancer Disease Incidence in Atomic Bomb Survivors, 1958–1998

We examined the relationships between the incidence of noncancer diseases and atomic bomb radiation dose using the longitudinal data for about 10,000 Adult Health Study (AHS) participants during 1958-1998. The current report updates the analysis we presented in 1993 with 12 additional years of follow-up. In addition to the statistically significant positive linear dose-response relationships detected previously for the incidence of thyroid disease (P < 0.0001), chronic liver disease and cirrhosis (P = 0.001), and uterine myoma (P < 0.00001), we also found a significant positive dose response for cataract (P = 0.026), a negative linear dose-response relationship for glaucoma (P = 0.025), and significant quadratic dose-response relationships for hypertension (P = 0.028) and for myocardial infarction among survivors exposed at less than 40 years of age (P = 0.049). Significant radiation effects for calculus of the kidney and ureter were evident for men but not for women (test of heterogeneity by sex: P = 0.007). Accounting for smoking and drinking did not alter the results. Radiation effects for cataract, glaucoma, hypertension, and calculus of the kidney and ureter in men are new findings. These results attest to the need for continued follow-up of the aging A-bomb survivors to fully elucidate the effects of radiation exposure on the occurrence of noncancer diseases.

Expressão da proteína tgfbeta1 em coração irradiado in vivo

OBJETIVO: Avaliar, no coração, por imuno-histoquímica, a localização das proteínas TGFbeta1 latente e TGFbeta1 ativa, se ocorre ativação radioinduzida da proteína TGFbeta1 latente, e a distribuição das fibras colágenas em diversos períodos de tempo após irradiação. MATERIAIS E MÉTODOS: Trinta e dois camundongos isogênicos (C57BL) foram divididos em dois grupos: GI (não irradiado), com 12 animais, e GII (irradiado), com 20 animais. Os animais do GII receberam radiação gama (telecobaltoterapia, 60Co, com rendimento de 0,97 Gy/min., dose única de 7 Gy em corpo inteiro). Os camundongos dos grupos I e II foram sacrificados por estiramento cervical nos períodos de 1, 14, 30 e 90 dias após irradiação. RESULTADOS: Os corações irradiados apresentaram: 1) alterações nucleares e diminuição das estriações das células musculares cardíacas; 2) aumento significante da deposição de fibras colágenas aos 90 dias depois da irradiação; 3) ativação da proteína TGFbeta1 latente em cardiomiócitos e células do conjuntivo depois da irradiação. CONCLUSÃO: Nossos resultados mostram a importância da proteína TGFbeta1 no processo de fibrose cardíaca radioinduzida e sugerem que células do parênquima (cardiomiócitos) e do conjuntivo podem participar deste mecanismo atuando como fontes da proteína TGFbeta1 ativa.

Coronary artery brachytherapy

Coronary artery disease is the leading cause of mortality in the West with over 1.2 million angioplasties performed annually. Despite the introduction of stents, restenosis occurs in 30-40% of vessels, which until recently has only been treated effectively by coronary artery bypass surgery. Coronary artery brachytherapy appears to provide an alternative, less invasive remedy. The mechanisms of restenosis and how these are inhibited by radiation are described here. The practicalities of radiation delivery and the history of the development of intravascular radiation as an effective clinical tool are outlined. Finally, the pitfalls of the current technology and the areas in which future research must be targeted for the field to develop are discussed.

Partial irradiation of the heart

Radiation-induced heart disease (RIHD) includes pericarditis, ischemic heart disease, and myocardial infarction and leads in some cases to fatal complications. It has been shown that the increased survival due to radiotherapy could be negated by excess deaths from RIHD in breast cancer radiotherapy for left-sided tumors. Subclinical effects following irradiation have been detected in several studies both of breast cancer and Hodgkin's irradiation. The dose-volume response relationships describing cardiac complications have been studied for pericarditis and cardiac mortality by means of biologic models, including the well-known Lyman-Kutcher-Burman (LKB) model and Källman's relative seriality model. Studies by Martel and coworkers on pericarditis and by Gagliardi and coworkers on cardiac mortality are reviewed. The anatomical and functional definition of the heart represents a key issue in modeling, as it affects strongly the dosimetrical data to be used as input data in the models. Several treatment strategies to decrease heart irradiation, based on models and/or based on dose-distribution evaluations, are reviewed. It is concluded that left-sided breast cancer patients should always be 3-dimensional (3D) dose planned.

Prognostic role of pericardial fluid cytology in cardiac tamponade associated with non-small cell lung cancer

BACKGROUND AND STUDY OBJECTIVES

Cardiac tamponade is a life-threatening complication of non-small cell lung cancer (NSCLC). Malignant pericardial effusion signifies advanced disease, but the significance of a negative pericardial fluid cytology in patients with advanced lung cancer is still controversial. The differential diagnosis of cytology-negative pericardial effusion is difficult and sometimes impossible. The purpose of this study is to determine the prognostic role of pericardial fluid cytology in patients with NSCLC and cardiac tamponade.

DESIGN

Retrospective review of patients with concurrent NSCLC and cardiac tamponade over a 10-year period.

METHODS AND RESULTS

Eighty-two patients were included in this study. Pericardial fluid cytology was positive in 60 patients and negative in 22 patients. The overall median survival was 74.5 days, and 1-year survival was 7.3%, with no survival difference between the two groups (p = 0.2506). However, there was a significant survival difference after different treatment strategies. Patients receiving systemic chemotherapy survived longer than those receiving local therapy (p<0.001), and these patients, in turn, survived longer than those receiving supportive treatment (p<0.001).

CONCLUSIONS

When patients have concurrent advanced NSCLC and cardiac tamponade, the most likely cause of the pericardial effusion is the cancer itself, regardless of the results of the cytologic examination. Our results suggest that systemic chemotherapy might prolong survival in such patients, but further prospective, randomized study is necessary.

Cardiac systolic function before and after hematopoietic stem cell transplantation

In order to examine the effect of hematopoietic stem cell transplantation (HSCT) on cardiac systolic function, we measured left ventricular ejection fraction (LVEF) by radioventriculography (RVG) before and after the transplantation procedure. One hundred and forty-eight patients were examined, 96 undergoing allogeneic grafting and 52 autologous. Fifty patients had CML, 48 AML, 21 ALL, 18 multiple myeloma and 11 breast cancer. The second RVG examination was performed 22 to 227 days (median 60 days) after HSCT. The mean LVEF value in the whole patient group was 60.2% (range 39-81%) before and 61.1% (35-86%) after transplantation. Patients with CML had significantly higher LVEF before transplantation than patients with acute leukemia (P = 0.007) and multiple myeloma (P = 0.005). No significant changes in mean LVEF between the pre- and post-transplant measurements were seen in any of the diagnostic subgroups or in allogeneic or autologous recipients. None of the 148 patients in the study has shown any signs of clinical heart failure at 2, 5 to 10 years follow-up. Patients who had received anthracyclines in the previous treatment had significantly lower LVEF before transplantation but showed no increased risk of decline in cardiac function. In conclusion, the HSCT procedure does not seem to affect myocardial function 1-7 months after transplantation.

Long-term cardiac mortality following radiation therapy for Hodgkin's disease: analysis with the relative seriality model

PURPOSE

(a) To assess the increased risk of death due to ischemic heart disease (IHD) in a group of patients treated for Hodgkin's disease (HD) with radiation therapy (RT) as the primary treatment. (b) To quantify the dose response of IHD using a biophysical model.

MATERIALS AND METHODS

Patient material consisted of 157 patients diagnosed for HD between 1972 and 1985 who received RT as the primary treatment at Radiumhemmet, Karolinska Hospital. The general population formed the control group. The RT treatments were reconstructed based on the individual treatment data and simulator films. Individual clinical and dosimetrical data were analyzed with the relative seriality model. The material was also analyzed grouping the material according to dose-volume constraints.

RESULTS

Of the 157 patients, 13 (8.3%) died due to IHD. The standardized mortality ratio (SMR) was 5.0 (95% CI, 2.7-8.6). Analysis of dose-volume histograms (DVH) showed an increasing risk with increasing dose to a larger volume fraction. The observed individual clinical complication data could not be modeled unambiguously. The group analysis resulted in the dose-response parameters: D(50)=71 Gy, gamma=0.96 and s=1.0.

CONCLUSIONS

A significantly increased risk of death due to IHD following RT for HD was found. The risk was found to increase with higher dose and larger volume fraction irradiated.

Recurrent cardiac tamponade treated using a pericardio-venous shunt

A 49-year-old woman was admitted because of recurrent cardiac tamponade. She had undergone radical mastectomy and radiotherapy for left breast cancer four years previously. In the following two years, she felt short of breath on exertion due to cardiac tamponade. Repeated conservative therapy with diuretics and pericardial drainage were ineffective in terminating pericardial effusion. The therapeutic procedure of a pericardio-venous shunt was then employed and was effective for improving the recurrent symptoms.

Constrictive pericarditis in the modern era: evolving clinical spectrum and impact on outcome after pericardiectomy

BACKGROUND

The clinical spectrum of constrictive pericarditis (CP) has been affected by a change in incidence of etiological factors. We sought to determine the impact of these changes on the outcome of pericardiectomy.

METHODS AND RESULTS

The contemporary spectrum of CP in 135 patients (76% male) evaluated at the Mayo Clinic from 1985 to 1995 was compared with that of a historic cohort. Notable trends were an increasing frequency of CP due to cardiac surgery and mediastinal radiation and presentation in older patients (median age, 61 versus 45 years). Perioperative mortality decreased (6% versus 14%, P = 0.011), but late survival was inferior to that of an age- and sex-matched US population (57+/-8% at 10 years). The long-term outcome was predicted independently by 3 variables in stepwise logistic regression analyses: (1) age, (2) NYHA class, and most powerfully, (3) a postradiation cause. Of 90 late survivors in whom functional class could be determined, functional status had improved markedly (2.6+/-0.7 at baseline versus 1.5+/-0.8 at latest follow-up [P<0.0001]), with 83% being free of clinical symptoms.

CONCLUSIONS

The evolving profile of CP, with increasingly older patients and those with radiation-induced disease in the past decade, significantly affects postoperative prognosis. Long-term results of pericardiectomy are disappointing for some patient groups, especially those with radiation-induced CP. By contrast, surgery alleviates or improves symptoms in the majority of late survivors.

Theoretical assessment of late cardiac complication from endovascular brachytherapy for restenosis prevention

PURPOSE

In this study, a theoretical assessment of late cardiac complication from endovascular brachytherapy is performed using the integrated logistic model.

MATERIALS AND METHODS

Calculation were performed for various lengths of Ir-192 sources using alpha/beta = 3.2 for the endpoint of chronic ischemia, TD50/5 = 7,000 cGy, and TD5/5 = 5,000 cGy. The dose distribution over a standard heart was divided into volume elements with uniform dose (dose-volume histogram). Using linear-quadratic equation, the dose in each of the volume elements was converted into dose equivalent to standard fractionation external beam irradiation. The normal tissue complication probability (NTCP) for each volume element was calculated and combined together to arrive at the cumulative risk of late cardiac complication. The NTCP was plotted against the dose prescribed at 2-mm radial distance for four treatment lengths.

RESULTS

(1) The overall risk of late cardiac toxicity (chronic ischemia within 5 years) was estimated to be less than 1% for current clinical trials using Ir-192. (2) There is a volume effect with higher risk for larger irradiated volume, which can come from longer treatment time, the same dose prescribed at a greater radial distance, and a longer source train. (3) The NTCP vs. dose demonstrates a sigmoidal relationship. There is a threshold dose (about 500 cGy), below which the risk is minimal; the gradient of the curve is greater for longer treatment length.

CONCLUSION

If the prediction from this model is validated with clinical data, it will contribute to guidelines for dose prescription, dose escalation, evaluation of new source design, and multivessel treatment.

Vasculopathy of small muscular arteries in pediatric patients after bone marrow transplantation

Bone Marrow Transplant (BMT) is a critical therapeutic intervention for a variety of diseases occurring in the pediatric patient. Complications of allogeneic BMT include graft-versus-host disease (GVHD), infection, drug toxicity, thrombotic microangiopathy, and veno-occlusive disease. With solid organ transplantation, chronic vascular rejection has emerged as a major factor limiting long-term survival of the graft. We present a vasculopathy of small muscular arteries in 6 patients after allogeneic BMT. Cases include 4 boys and 2 girls ranging in age from 4 months to 13 years with full or partial human leukocyte antigen matching. Five of the 6 transplants were from related donors. The vasculopathy occurred 13 to 418 days after transplant and was noted in surgical specimens (2) and at autopsy (4). It was seen in the gastrointestinal tract and lung in 3 cases each. Vascular changes in small muscular arteries include concentric intimal or medial hyperplasia with luminal narrowing, prominent myxoid change, extravasated red blood cells, and presence of some foamy histiocytes with no evidence of thrombotic microangiopathy. Vasculopathy contributed to intestinal compromise requiring surgical intervention 3 times in 1 patient, and diffuse alveolar damage with hemorrhage in another. All 6 patients are dead. The cause of this unusual vasculopathy present in patients after BMT is likely to be multifactorial, involving effects of irradiation, chemotherapy, cyclosporine, and GVHD. Together these may create a negative synergy which produces an obliterative arteriopathy that should be recognized as a pathological entity and may be a harbinger of a poor prognosis.

Effects of intraoperative irradiation (IORT) and intraoperative hyperthermia (IOHT) on canine sciatic nerve: histopathological and morphometric studies

PURPOSE/OBJECTIVE

Peripheral neuropathies have emerged as the major dose-limiting complication reported after intraoperative radiation therapy (IORT). The combination of IORT with hyperthermia may further increase the risk of peripheral nerve injury. The objective of this study was to evaluate histopathological and histomorphometric changes in the sciatic nerve of dogs, after IORT with or without hyperthermia treatment.

METHODS AND MATERIALS

Young adult beagle dogs were randomized into five groups of 3-5 dogs each to receive IORT doses of 16, 20, 24, 28, or 32 Gy. Six groups of 4-5 dogs each received IORT doses of 12, 16, 20, 24, or 28 Gy simultaneously with 44 degrees C of intraoperative hyperthermia (IOHT) for 60 min. One group of dogs acted as hyperthermia-alone controls. Two years after the treatment, dogs were euthanized, and histopathological and morphometric analyses were performed.

RESULTS

Qualitative histological analysis showed prominent changes such as focal necrosis, mineralization, fibrosis, and severe fiber loss in dogs which received combined treatment. Histomorphometric results showed a significantly higher decrease in axon and myelin and small blood vessels, with a corresponding increase in connective tissue in dogs receiving IORT plus hyperthermia treatment. The effective dose for 50% of nerve fiber loss (ED50) in dogs exposed to IORT only was 25.3 Gy. The ED50 for nerve fiber loss in dogs exposed to IORT combined with IOHT was 14.8 Gy. The thermal enhancement ratio (TER) was 1.7.

CONCLUSION

The probability of developing peripheral neuropathies in a large animal model is higher when IORT is combined with IOHT, when compared to IORT application alone. To minimize the risk of peripheral neuropathy, clinical treatment protocols for the combination of IORT and hyperthermia should not assume a thermal enhancement ratio (TER) to be lower than 1.5.

[Intravascular irradiation in the combined therapy and prevention of restenosis. Overview]

Despite numerous efforts in catheter technology and procedural approaches the problem of restenosis in interventional cardiology persists. Although the implantation of coronary stents has significantly reduced restenosis rates based on the inhibition of elastic recoil, intimal proliferation as the second major mechanism for postinterventional restenosis could not effectively be suppressed. Intimal proliferation is the response to vessel injury following interventional procedure, e.g. balloon angioplasty. It results in the adhesion of mono- and lymphocytes which themselves trigger the colonisation of myofibroblasts. Intracoronary irradiation seeks to prevent this proliferative process as it destroys or irreversibly alters DNA structures of cells at the site of balloon injury. The antiproliferative effect depends on the irradiation dosis, the timing and the cell cycle phase. Mainly beta- and gamma-radiation is used for intracoronary irradiation. Beta-emitters are characterized by a sharp decline of dose rate within millimeters from the actual source. The exposure to surrounding tissue as well the catheter staff can be kept to a minimum. The high intensity of beta-emitters allow a short treatment period of minutes to gain an effective radiation dose to the target. In contrast, gamma-emitters have a low radial dose distribution resulting in high dosage even centimeters away from the source. These emitters require additional shielding in the catheter laboratory and lead to excessive whole body doses. To achieve a sufficient dose in the target tissue, irradiation times of more than 20 minutes are necessary which prolongs the interventional procedure substantially. At present, catheter based systems or radioactive implantable stents are available to deliver the required dose. Catheter based systems seem more flexible in a number of considerations. On the other hand they require a substantial amount of hardware. Beta-emitting stents are implanted via a conventional stent delivery system with small shielding modifications. However, stents emit an inhomogeneous radiation profile due to the mesh-like structure. In addition, not every lesion can be reached by a stent nor does every lesion require a stent solely to deliver radiation. External irradiation is presently not recommended due to its ineffectiveness and the high rate of side effects. In the experimental setting the porcine model comes closest to the clinical situation in man. Animal experiments have demonstrated the effective reduction of intimal proliferation using beta- and gamma-sources in a wide dose range of 3 to 56 Gy. Although the initial and early results are convincing little is know about the long term results. Only few studies have been and are currently performed in patients. Some of these investigations demonstrate a significant reduction of restenosis rate after 6 months. Again, information on long-term results are lacking. It has to be considered that perivascular fibrosis, which may occur with a delay of 5 to 10 years depending on the dosage, could curtail the initial success. Intracoronary irradiation is a promising method for the prevention of restenosis. The dose finding with respect to the dose effect relation, the determination of the therapeutic window and the timing of irradiation have to be further defined in the clinical setting. Nevertheless, intracoronary irradiation remains high on the priority list in fighting restenosis.

Complete AV block following mediastinal radiation therapy: electrocardiographic and pathologic correlation and review of the world literature

The clinical, features, serial electrocardiograms, and autopsy findings of a patient with symptomatic complete AV block, who had received mediastinal radiation therapy 8 1/2 years previously, are presented. The cardiac histopathology disclosed immense fibrosis of the conduction system and of the atria and ventricles. The enormous amount of fibrosis was similar in location and intensity to that observed in our previously reported patient (Cohen et al., Arch Intern Med 1981; 141:676-679) who had undergone mediastinal radiation. We conclude that the severe fibrosis was primarily due to radiation, rather than secondary to atherosclerotic coronary artery disease, which also has been described as a consequence of mediastinal radiotherapy. This patient's serial electrocardiograms disclosed evidence of complete block both in the AV nodal area and infra His system, which correlated well with the histopathology. The characteristic clinical features of patients with symptomatic complete AV block post mediastinal radiation therapy are presented, along with a review of the world literature.