Comparison of the dose on specific 3DCT images and the accumulated dose for cardiac structures in esophageal tumors radiotherapy: whether specific 3DCT images can be used for dose assessment?

BACKGROUND: Cardiac activity could impact the accuracy of dose assessment for the heart, pericardium and left ventricular myocardium (LVM). The purpose of this study was to explore whether it is possible to perform dose assessment by contouring the cardiac structures on specific three-dimensional computed tomography (3DCT) images to reduce the impact of cardiac activity. METHODS: Electrocardiograph-gated 4DCT (ECG-gated 4DCT) images of 22 patients in breath-hold were collected. MIM Maestro 6.8.2 (MIM) was used to reconstruct specific 3DCT images to obtain the Maximal intensity projection (MIP) image, Average intensity projection (AIP) image and Minimum intensity projection (Min-IP) image. The heart, pericardium and LVM were contoured in 20 phases of 4DCT images (0, 5%... 95%) and the MIP, AIP and Min-IP images. Then, a radiotherapy plan was designed at the 0% phase of the 4DCT images, and the dose was transplanted to all phases of 4DCT to acquire the dose on all phases, the accumulated dose of all phases was calculated using MIM. The dose on MIP, AIP and Min-IP images were also obtained by deformable registration of the dose. The mean dose (Dmean), V5, V10, V20, V30 and V40 for the heart, pericardium and LVM in MIP, AIP and Min-IP images were compared with the corresponding parameters after dose accumulation. RESULTS: The mean values of the difference between the Dmean in the MIP image and the Dmean after accumulation for the heart, pericardium and LVM were all less than 1.50 Gy, and the dose difference for the pericardium and LVM was not statistically significant (p > 0.05). For dose-volume parameters, there was no statistically significant difference between V5, V10, and V20 of the heart and pericardium in MIP, AIP, and Min-IP images and those after accumulation (p > 0.05). For the LVM, only in the MIP image, the differences of V5, V10, V20, V30 and V40 were not significant compared to those after dose accumulation (p > 0.05). CONCLUSIONS: There was a smallest difference for the dosimetry parameters of cardiac structures on MIP image compared to corresponding parameters after dose accumulation. Therefore, it is recommended to use the MIP image for the delineation and dose assessment of cardiac structures in clinical practice.

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.

Doses of radiation to the pericardium, instead of heart, are significant for survival in patients with non-small cell lung cancer.

BACKGROUND AND PURPOSE: Higher cardiac dose was associated with worse overall survival in the RTOG0617 study. Pericardial effusion (PCE) is a common cardiac complication of thoracic radiation therapy (RT). We investigated whether doses of radiation to the heart and pericardium are associated with PCE and overall survival in patients treated with thoracic radiation for non-small cell lung cancer (NSCLC). MATERIALS AND METHODS: A total of 94 patients with medically inoperable/unresectable NSCLC treated with definitive RT in prospective studies were reviewed for this secondary analysis. Heart and pericardium were contoured consistently according to the RTOG1106 Atlas, with the great vessels and thymus of the upper mediastinal structures included in the upper part of pericardium, only heart chambers included in the heart structure. Clinical factors and dose-volume parameters associated with PCE or survival were identified via Cox proportional hazards modeling. The risk of PCE and death were mapped using DVH atlases. RESULTS: Median follow-up for surviving patients was 58 months. The overall rate of PCE was 40.4%. On multivariable analysis, dosimetric factors of heart and pericardium were significantly associated with the risk of PCE. Pericardial V30 and V55 were significantly correlated with overall survival, but presence of PCE and heart dosimetric factors were not. CONCLUSION: PCE was associated with both heart and pericardial doses. The significance of pericardial dosimetric parameters, but not heart chamber parameters, on survival suggests the potential significance of radiation damage to the cranial region of pericardium.

Epicardial infrared ablation to create a linear conduction block on a beating right atrium.

BACKGROUND: It is still difficult to create a secure linear conduction block on a beating heart from the epicardial side. To overcome this drawback we developed an infrared coagulator equipped with a cuboid light-guiding quartz rod. This study was designed to electrophysiologically confirm the efficacy of a new ablation probe using infrared energy in a clinical case. METHODS: The infrared light from a lamp is focused into the newly developed cuboid quartz rod, which has a rectangular distal exit-plane that allows 30 mm × 10 mm linear photocoagulation. Two pairs of electrodes were attached to the right atrium of a patient who was undergoing surgery. Each pair of electrodes was placed 10 mm from an ablation line. The change in conduction time between the two pairs of electrodes was measured during ablation. The predicted conduction time delay ratio was 1.54. RESULTS: The actual conduction time after ablation was 1.38-1.43 times longer than the pre-ablation conduction time. CONCLUSIONS: The infrared ablation using a newly developed cuboid probe made it possible to create a linear conduction block on the beating right atrial free wall clinically.

Quantification of variation in dose-volume parameters for the heart, pericardium and left ventricular myocardium during thoracic tumor radiotherapy.

Cardiac activity can induce dose-volume evaluation errors for cardiac structures. The purpose of this study was to quantify the variation in dose-volume parameters for the heart, pericardium and left ventricular myocardium (LVM) throughout the cardiac circle. The heart, pericardium and LVM of 22 patients were contoured on 20 phases of electrocardiography-gated 4D computed tomography (4DCT) images acquired during breath-hold. Radiotherapy plans were designed on 0% phase of the 4DCT images, and the dose distributions of the plans were imported into MIM Maestro and deformed to each phase to generate distributions for all phases. Variations in dose-volume parameters for the heart, pericardium and LVM were compared among different phases. The rates of variation in Dmean for the heart and pericardium were 3.33 ± 1.04% and 2.66 ± 1.15%, respectively. The mean values of the maximum difference in V5, V10, V20, V30 and V40 were all <2% for the heart and pericardium and were not statistically significant (P > 0.05). The rate of variation in Dmean for the LVM reached 87.05 ± 38.34%, and the maximum differences in V5, V10, V20, V30 and V40 were 13.76 ± 4.46%, 13.64 ± 4.33%, 12.84 ± 4.55%, 11.62 ± 4.85% and 3.63 ± 2.56%, respectively; all differences were statistically significant (P < 0.05). Variations in dose-volume parameters were more significant in the LVM than in the heart and pericardium (P < 0.05). The dose-volume parameters for the LVM were significantly influenced by cardiac activity, whereas those for the heart and pericardium were not; therefore, individual dosimetric evaluation and limitation must be performed for the LVM.

Undifferentiated sarcoma of the pericardium after radiation therapy for Hodgkin's lymphoma.

Primary sarcomas of the pericardium are extremely rare malignant tumors of the heart. The incidence of sarcoma increases after radiation therapy in the field of breast. The specific features of this case report are the difficulties in diagnostics of undifferentiated spindle-cell sarcoma of the pericardium and the connection between the disease and the radiation therapy for Hodgkin's lymphoma.

Constrictive Pericarditis 5 Months after Radiation Therapy in a 62-Year-Old Woman with Esophageal Cancer.

Most pericardial changes appear within a few weeks in patients who have undergone radiation therapy for thoracic neoplasms. Chronic pericardial constriction typically occurs decades later, consequent to fibrosis. Early constrictive pericarditis after chest irradiation is quite rare. We report the case of a 62-year-old woman who underwent radiation therapy for esophageal cancer and presented with constrictive pericarditis 5 months later. We searched the English-language medical literature from January 1986 through December 2015 for reports of early constrictive pericarditis after irradiation for thoracic malignancies. We defined "early" as a diagnosis within one year after radiation therapy. Five cases fit our criteria, and we summarize the findings here. To our knowledge, ours is the first definitive report of a patient with esophageal cancer to present with early radiation-induced constrictive pericarditis. We conclude that constrictive pericarditis can occur early after radiation for thoracic malignancies, albeit rarely. When planning care for cancer patients, awareness of this sequela is helpful.

The Impact of Cardiac Radiation Dosimetry on Survival After Radiation Therapy for Non-Small Cell Lung Cancer.

PURPOSE: The heart receives high radiation doses during radiation therapy of advanced-stage lung cancer. We have explored associations between overall survival, cardiac radiation doses, and electrocardiographic (ECG) changes in patients treated in IDEAL-CRT, a trial of isotoxically escalated concurrent chemoradiation delivering tumor doses of 63 to 73 Gy. METHODS AND MATERIALS: Dosimetric and survival data were analyzed for 78 patients. The whole heart, pericardium, AV node, and walls of left and right atria (LA/RA-Wall) and ventricles (LV/RV-Wall) were outlined on radiation therapy planning scans, and differential dose-volume histograms (dDVHs) were calculated. For each structure, dDVHs were approximated using the average dDVH and the 10 highest-ranked structure-specific principal components (PCs). ECGs at baseline and 6 months after radiation therapy were analyzed for 53 patients, dichotomizing patients according to presence or absence of "any ECG change" (conduction or ischemic/pericarditis-like change). All-cause death rate (DR) was analyzed from the start of treatment using Cox regression. RESULTS: 38% of patients had ECG changes at 6 months. On univariable analysis, higher scores for LA-Wall-PC6, Heart-PC6, "any ECG change," and larger planning target volume (PTV) were significantly associated with higher DR (P=.003, .009, .029, and .037, respectively). Heart-PC6 and LA-Wall-PC6 represent larger volumes of whole heart and left atrial wall receiving 63 to 69 Gy. Cardiac doses ≥63 Gy were concentrated in the LA-Wall, and consequently Heart-PC6 was highly correlated with LA-Wall-PC6. "Any ECG change," LA-Wall-PC6 scores, and PTV size were retained in the multivariable model. CONCLUSIONS: We found associations between higher DR and conduction or ischemic/pericarditis-like changes on ECG at 6 months, and between higher DR and higher Heart-PC6 or LA-Wall-PC6 scores, which are closely related to heart or left atrial wall volumes receiving 63 to 69 Gy in this small cohort of patients.

Dosimetric predictors of radiation-induced pericardial effusion in esophageal cancer.

PURPOSE: To evaluate the dose-volume parameters of the pericardium and heart in order to reduce the risk of radiation-induced pericardial effusion (PE) and symptomatic PE (SPE) in esophageal cancer patients treated with concurrent chemoradiotherapy. METHODS: In 86 of 303 esophageal cancer patients, follow-up CT was obtained at least 24 months after concurrent chemoradiotherapy. Correlations between clinical factors, including risk factors for cardiac disease, dosimetric factors, and the incidence of PE and SPE after radiotherapy were analyzed using Cox proportional hazard regression analysis. Significant dosimetric factors with the highest hazard ratios were investigated using zones separated according to their distance from esophagus. RESULTS: PE developed in 49 patients. Univariate analysis showed the mean heart dose, heart V5-V55, mean pericardium dose, and pericardium V5-V50 to all significantly affect the incidence of PE. Additionally, body surface area was correlated with the incidence of PE in multivariate analysis. Grade 3 and 4 SPE developed in 5 patients. The pericardium V50 and pericardium D10 significantly affected the incidence of SPE. The pericardium V50 in patients with SPE ranged from 17.1 to 21.7%. Factors affecting the incidence of SPE were the V50 of the pericardium zones within 3 cm and 4 cm of the esophagus. CONCLUSION: A wide range of radiation doses to the heart and pericardium were related to the incidence of PE. A pericardium V50 ≤ 17% is important to avoid symptomatic PE in esophageal cancer patients treated with concurrent chemoradiotherapy.

Radiation-related heart and vascular disease.

Improvement in cancer therapy has led to increasing number of cancer survivors, some of whom have previously been treated with mediastinal radiation. Cardiac complication may manifest years after completion of radiation therapy. Hence long-term follow-up is essential in these patients. In this paper, we have discussed the short- and long-term cardiovascular side effects of radiation therapy.

Radiation- and anthracycline-induced cardiac toxicity and the influence of ErbB2 blocking agents.

In Her2-positive breast cancer patients, inhibition of epidermal growth factor receptor 2 (ErbB2)-signaling is often combined with chemotherapy and radiotherapy. The risk of cardiac toxicity after anthracyclines and radiotherapy is recognized, but little is known about increased risk when these treatments are combined with ErbB2 inhibition. This study investigated whether ErbB2 inhibition increased radiation or anthracycline-induced toxicity. In an in vitro study, human cardiomyocytes were treated with irradiation or doxorubicin, alone or in combination with trastuzumab, and evaluated for cell survival and growth. Groups of mice received 0 or 14 Gy to the heart, alone or in combination with lapatinib, or 3 × 4 mg/kg doxorubicin alone or in combination with lapatinib. Mice were evaluated 40 weeks after treatment for cardiac damage. Changes in cardiac function ((99m)Tc-Myoview gated SPECT) were related to histomorphology and microvascular damage. Radiation or doxorubicin-induced cardiomyocyte toxicity (in vitro) were not exacerbated by trastuzumab. Cardiac irradiation of mice decreased microvascular density (MVD) and increased endothelial damage in surviving capillaries (decrease alkaline phosphatase expression and increased von Willebrand factor), but these changes were not exacerbated by lapatinib. Inflammatory responses in the irradiated epicardium (CD45+ and F4/80+ cells) were significantly reduced in combination with lapatinib. Irradiation, doxorubicin, and lapatinib each induced cardiac fibrosis but this was not further enhanced when treatments were combined. At the ultra-structural level, both lapatinib and doxorubicin induced mitochondrial damage, which was enhanced in combined treatments. Lapatinib alone also induced mild changes in cardiac function but this was not enhanced in the combined treatments. Trastuzumab did not enhance direct radiation or anthracycline toxicity of cardiomyocytes in vitro. Lapatinib did not enhance the risk of radiation or anthracycline-induced cardiac toxicity in mice up to 40 weeks after treatment, but mitochondrial damage was more severe after doxorubicin combined with lapatinib.

Symptomatic pericardial effusion after chemoradiation therapy in esophageal cancer patients.

PURPOSE: We investigated clinical and treatment-related factors as predictors of symptomatic pericardial effusion in esophageal cancer patients after concurrent chemoradiation therapy. METHODS AND MATERIALS: We reviewed 214 consecutive primary esophageal cancer patients treated with concurrent chemoradiation therapy between 2001 and 2010 in our institute. Pericardial effusion was detected on follow-up computed tomography. Symptomatic effusion was defined as effusion ≥grade 3 according to Common Terminology Criteria for Adverse Events v4.0 criteria. Percent volume irradiated with 5 to 65 Gy (V5-V65) and mean dose to the pericardium were evaluated employing dose-volume histograms. To evaluate dosimetry for patients treated with two-dimensional planning in the earlier period (2001-2005), computed tomography data at diagnosis were transferred to a treatment planning system to reconstruct three-dimensional plans without modification. Optimal dosimetric thresholds for symptomatic pericardial effusion were calculated by receiver operating characteristic curves. Associating clinical and treatment-related risk factors for symptomatic pericardial effusion were detected by univariate and multivariate analyses. RESULTS: The median follow-up was 29 (range, 6-121) months for eligible 167 patients. Symptomatic pericardial effusion was observed in 14 (8.4%) patients. Dosimetric analyses revealed average values of V30 to V45 for the pericardium and mean pericardial doses were significantly higher in patients with symptomatic pericardial effusion than in those with asymptomatic pericardial effusion (P<.05). Pericardial V5 to V55 and mean pericardial doses were significantly higher in patients with symptomatic pericardial effusion than in those without pericardial effusion (P<.001). Mean pericardial doses of 36.5 Gy and V45 of 58% were selected as optimal cutoff values for predicting symptomatic pericardial effusion. Multivariate analysis identified mean pericardial dose as the strongest risk factor for symptomatic pericardial effusion. CONCLUSIONS: Dose-volume thresholds for the pericardium facilitate predicting symptomatic pericardial effusion. Mean pericardial dose was selected based not only on the optimal dose-volume threshold but also on the most significant risk factor for symptomatic pericardial effusion.

Use of irradiate animal pericardium membrane for prevention of Frey's syndrome after parotidectomy.

BACKGROUND: Frey syndrome is a common complication that appears few months after parotid surgery with flushing and sweating of the parotid-temporal area during mastication. It presumably originates from an aberrant nervous regeneration in which the parasympathetic fibers of the parotid gland would combine themselves with the sympathetic fibers of the sweat glands and with the cutaneous vessels. AIM: In the present study we analyze the effectiveness of a collagenous membrane derived from animal pericardium (APM) to prevent Frey's syndrome after parotidectomy. MATERIALS AND METHODS: We studied a total of 40 patients with benign tumors of the parotid gland, including 30 patients with pleomorphic adenoma, 7 patients with Warthin tumor and 3 with basal cells adenoma. The patients were divided into 2 groups: group 1 (experimental n=20) executed superficial parotidectomy with replacement of bovine pericardial matrix (BPM); group 2 (control n=20) underwent superficial parotidectomy followed by reposition of superficial musculoaponeurotic system (SMAS) flap. All patients were questioned over their subjective symptom and tested with Minor's test after 12 months from the intervention and introduced in a follow-up of 3 years. RESULTS: Subjectively Frey syndrome was referred in 5% of patients in group 1 and in 10% in group 2, while 0 cases were observed in group 1 after the starch-iodine test, 2 cases in group 2 (10%). CONCLUSIONS: Considering the present results, although this study needs further implementation, we can affirm that BPM is a valid option in preventing Frey's syndrome whereas SMAS flap is not available.

[Radiation-related heart toxicity]. / Toxicité cardiaque de la radiothérapie.

The radiotherapy of thoracic cancers exposes the heart to late radiation-induced complications. The physiopathological and clinical consequences of heart irradiation have been mostly studied in patients with Hodgkin lymphoma and breast cancer. The main cause of cardiac morbidity is radiation-induced coronaropathy with a relative risk estimated between 2 and 3 in earlier studies. Preexisting factors of cardiovascular risk, including chemotherapy, potentalize the cardiotoxicity of radiotherapy. Conformational radiotherapy, adapting the ballistics and the energy to the delineated volumes while carefully evaluating the dose-volume distribution in the organs at risk, allowed a drastic reduction in cardiac mortality. This toxicity no longer seems to be significant if the cardiac volume has received less than 30 Gy. Nevertheless, the prolonged life expectancy of cancer patients and the expanding use of new cardiotoxic anticancer drugs underline the persistent need to further reduce the dose delivered to the heart. Indeed, 1 Gy added to the mean heart dose would increase the cardiotoxic risk by 4% (IC 95%: 2-6%, P=0.0002). A strengthened collaboration between the radiation oncologist and the cardiologist aims at detecting and treating long-term complications after thoracic radiotherapy.

Helical tomotherapy for extramedullary hematopoiesis involving the pericardium in a patient with chronic myeloid leukemia.

Extramedullary hematopoiesis (EMH) refers to the development of foci of hematopoiesis outside its normal location in the bone marrow. This occurs normally during fetal development but is abnormal postpartum. The most common sites of EMH are the spleen and liver. The phenomenon occurs in a number of disease states, notably in myelofibrosis, thalassemia, immune thrombocytopenic purpura, sickle cell anemia, polycythemia vera, and myelodysplastic syndrome. Affected patients often develop symptoms related to the location of the EMH. Reported treatments include red blood cell transfusions, surgical excision, decompressive laminectomy in cases of cord compression, chemotherapy, and irradiation. Radiation therapy is highly effective for treating hematopoietic tissue because such tissues are extremely radiosensitive. Megavoltage helical tomotherapy is a technical advance in the delivery of radiation therapy, allowing more conformal and precise treatments. The present case report describes a patient with the diagnosis of atypical chronic myeloid leukemia and myelofibrosis who subsequently developed EMH of the pericardium with effusion and tamponade. By utilizing tomotherapy we were able to treat the pericardium while sparing much of the myocardium. The patient tolerated treatment well without acute adverse effects. His symptoms were alleviated, but he died approximately 1 year later.

Animal studies of epicardial atrial ablation.

The Cox maze procedure is an effective treatment of atrial fibrillation, with a long-term freedom from recurrence greater than 90%. The original procedure was highly invasive and required cardiopulmonary bypass. Modifications of the procedure that eliminate the need for cardiopulmonary bypass have been proposed, including use of alternative energy sources to replace cut-and-sew lesions with lines of ablation made from the epicardium on the beating heart. This has been challenging because atrial wall muscle thickness is extremely variable, and the muscle can be covered with an epicardial layer of fat. Moreover, the circulating intracavitary blood acts as a potential heat sink, making transmural lesions difficult to obtain. In this report, we summarize the use of nine different unidirectional devices (four radiofrequency, two microwave, two lasers, one cryothermic) for creating continuous transmural lines of ablation from the atrial epicardium in a porcine model. We define a unidirectional device as one in which all the energy is applied by a single transducer on a single heart surface. The maximum penetration of any device was 8.3 mm. All devices except one, the AtriCure Isolator pen, failed to penetrate 2 mm in some nontransmural sections. Future development of unidirectional energy sources should be directed at increasing the maximum depth and the consistency of penetration.

A new sterilization technique of bovine pericardial biomaterial using microwave radiation.

Bioprosthetic valves created from chemically treated natural tissues such as bovine pericardial biomaterial are used as heart valve scaffolds. Methods currently available for sterilization of biomaterial for transplantation include the application of gamma radiation and chemical sterilants. These techniques, however, can be problematic because they can be expensive and lead to a reduction in tissue integrity. Therefore, improved techniques are needed that are cost effective and do not disrupt the physical properties, functionality, and lifespan of the valvular leaflets. This study examined a novel technique using nonthermal microwave radiation that could lead to the inactivation of bacteria in bovine pericardial biomaterial without compromising valve durability. Two common pathogenic species of bacteria, Escherichia coli and Staphylococcus aureus, were used as test microorganisms. Optimized microwave parameters were used to determine whether inactivation of pathogenic bacteria from bovine pericardium could be achieved. In addition, the effect of microwave sterilization on tissue integrity was examined. The mechanical properties (assessed using dynamic mechanical analysis) and tensile strength testing (using a Universal Tensile Tester) as well as thermal analysis (using thermogravimetric analysis and differential scanning calorimetry) indicated that microwave sterilization did not compromise the functionality of bovine pericardial biomaterial. Scanning electron microscopy imaging and cytotoxicity testing also confirmed that the structure and biocompatibility of transplant biomaterial remained unaltered after the sterilization process. Results from the application of this new microwave (MW) sterilization technique to bovine pericardium showed that near-complete inactivation of the contaminant bacteria was achieved. It is concluded that nonthermal inactivation of pathogenic bacteria from bovine pericardial biomaterial could be achieved using microwave radiation.

Risk factors for pericardial effusion in inoperable esophageal cancer patients treated with definitive chemoradiation therapy.

PURPOSE: To identify clinical and dosimetric factors influencing the risk of pericardial effusion (PCE) in patients with inoperable esophageal cancer treated with definitive concurrent chemotherapy and radiation therapy (RT). METHODS AND MATERIALS: Data for 101 patients with inoperable esophageal cancer treated with concurrent chemotherapy and RT from 2000 to 2003 at our institution were analyzed. The PCE was confirmed from follow-up chest computed tomography scans and radiologic reports, with freedom from PCE computed from the end of RT. Log-rank tests were used to identify clinical and dosimetric factors influencing freedom from PCE. Dosimetric factors were calculated from the dose-volume histogram for the whole heart and pericardium. RESULTS: The crude rate of PCE was 27.7% (28 of 101). Median time to onset of PCE was 5.3 months (range, 1.0-16.7 months) after RT. None of the clinical factors investigated was found to significantly influence the risk of PCE. In univariate analysis, a wide range of dose-volume histogram parameters of the pericardium and heart were associated with risk of PCE, including mean dose to the pericardium, volume of pericardium receiving a dose greater than 3 Gy (V3) to greater than 50 Gy (V50), and heart volume treated to greater than 32-38 Gy. Multivariate analysis selected V30 as the only parameter significantly associated with risk of PCE. CONCLUSIONS: High-dose radiation to the pericardium may strongly increase the risk of PCE. Such a risk may be reduced by minimizing the dose-volume of the irradiated pericardium and heart.

Effects of gamma irradiation on mechanical behavior and calcification of glutaraldehyde-fixed bovine pericardium.

OBJECTIVE: To evaluate the effect of gamma irradiation on glutaraldehyde-fixed bovine pericardium. METHOD: Glutaraldehyde-fixed bovine pericardium was exposed to gamma radiation (doses from 0 to 10000 Gy). Six samples from each of nine groups were evaluated by optic microscopy, and shrinking and mechanical tests and the denaturation temperature was determined. Additionally, they were subcutaneously implanted in rats and after four months they were explanted and Ca2+ levels measured by atomic absorption spectroscopy. RESULTS: The Ca2+ levels were (in microg/mg): control (0 Gy) - 194.45; 50 Gy - 154.64; 100 Gy - 169.37; 200 Gy - 163.64; 500 Gy - 199.89; 1000 Gy - 184.02; 2000 Gy - 198.95; 5000 Gy - 227.95; 10000 Gy - 362.62. Gamma irradiation caused a significant effect on the biomechanical properties of the tissue. CONCLUSION: e-fixed bovine pericardium.