Risk scores' performance and their impact on operative decision-making in left-sided endocarditis: a cohort study.

The accuracy of contemporary risk scores in predicting perioperative mortality in infective endocarditis (IE) remains controversial. The aim is to evaluate the performance of existent mortality risk scores for cardiovascular surgery in IE and the impact on operability at high-risk thresholds. A single-center retrospective review of adult patients diagnosed with acute left-sided IE undergoing surgery from May 2014 to August 2019 (n = 142) was done. Individualized risk calculation was obtained according to the available mortality risk scores: EuroScore I and II, PALSUSE, Risk-E, Costa, De Feo-Cotrufo, AEPEI, STS-risk, STS-IE, APORTEI, and ICE-PCS scores. A cross-validation analysis was performed on the score with the best area under the curve (AUC). The 30-day survival was 96.5% (95%CI 91-98%). The score with worse area under the curve (AUC = 0.6) was the STS-IE score, while the higher was for the RISK-E score (AUC = 0.89). The AUC of the majority of risk scores suggested acceptable performance; however, statistically significant differences in expected versus observed mortalities were common. The cross-validation analysis showed that a large number of survivors (> 75%) would not have been operated if arbitrary high-risk threshold estimates had been used to deny surgery. The observed mortality in our cohort is significantly lower than is predicted by contemporary risk scores. Despite the reasonable numeric performance of the analyzed scores, their utility in judging the operability of a given patient remains questionable, as demonstrated in the cross-validation analysis. Future guidelines may advise that denial of surgery should only follow a highly experienced Endocarditis Team evaluation.

Unilateral pulmonary edema associated factors after minimally invasive mitral valve surgery.

BACKGROUND AND OBJECTIVES: In recent years, minimally invasive cardiac surgery (MICS) has been developed and applied to a greater number of pathologies, especially in mitral valve surgeries, as it obtains results comparable to those of conventional techniques while entailing lower surgical trauma and shorter recovery time. MICS requiring one-lung ventilation has been associated to the appearance of unilateral pulmonary edema (UPE), which is a potentially serious complication. The objective is determining the incidence of UPE after mitral MICS and its development associated factors. MATERIAL AND METHODS: Observational descriptive and single-center study analyzing data from patients undergoing mitral valve MICS (right mini-thoracotomy) consecutively collected between the years 2015 and 2017. RESULTS: A total of 93 patients were included and 26 presented UPE. The most common complications after mitral valve MICS were atrial fibrillation (38.7%), UPE (28%) and transient and/or definitive second- or third-degree auriculoventricular block (19.4%). The UPE group had longer ICU stay (3.3 ± 8.0 vs. 1.84 ± 2.23 days) and longer total hospitalization length-of-stay (15.5 ± 34.7 vs. 10.6 ± 7.5 days). The mortality in the UPE group was 3.9%. A significant association was found between the following collected variables and the development of postoperative UPE: preoperative baseline pulse oximetry, preoperative use of ACE inhibitors, postoperative atrial fibrillation and 24 first-hours cumulative chest tube drainage volume on the first 24 h. CONCLUSIONS: The incidence of UPE is high and its appearance is associated with a longer ICU and total length of stay. More studies are required to understand its pathophysiology and apply measures to help decreasing its appearance.

Factores asociados al edema pulmonar unilateral después de la cirugía mínimamente invasiva de la válvula mitral / Unilateral pulmonary edema associated factors after minimally invasive mitral valve surgery

Antecedentes y objetivo: En los últimos años la cirugía cardíaca mínimamente invasiva (CCMI) se ha desarrollado y aplicado a mayor número de dolencias, especialmente en cirugías sobre la válvula mitral, por presentar resultados comparables a las técnicas convencionales con menor agresividad y tiempo de recuperación. La CCMI que necesita ventilación unipulmonar se ha asociado a la aparición de edema pulmonar unilateral (EPU), que constituye una complicación potencialmente grave. El objetivo es determinar la incidencia de EPU tras CCMI mitral y los factores asociados a su desarrollo. Material y métodos: Estudio observacional descriptivo y unicéntrico. Se analizaron los pacientes tratados con CCMI sobre válvula mitral (minitoracotomía derecha), recogidos de manera consecutiva entre los años 2015 y 2017. Resultados: Se incluyó a un total de 93 pacientes, de los cuales 26 presentaron EPU. Las complicaciones más habituales tras la CCMI mitral fueron: fibrilación auricular (38,7%), EPU (28%) y bloqueo auriculoventricular de segundo o tercer grado transitorio o definitivo (19,4%). El grupo EPU presentó mayor tiempo de estancia en UCI (3,3±8,0 vs. 1,84±2,23 días) y mayor tiempo total de hospitalización (15,5±34,7 vs. 10,6±7,5 días). La mortalidad en el grupo EPU fue del 3,9%. Se encontró asociación significativa entre las siguientes variables recogidas y el desarrollo de EPU postoperatorio: pulsioximetría basal preoperatoria, uso preoperatorio de IECA, fibrilación auricular postoperatoria y volumen de drenajes en las primeras 24h. Conclusiones: La incidencia de EPU es elevada y su aparición se asocia a mayor estancia en UCI y mayor tiempo total de hospitalización. Se requieren más estudios para comprender su fisiopatología y aplicar medidas que ayuden a disminuir su aparición.(AU)

Background and objectives: In recent years, minimally invasive cardiac surgery (MICS) has been developed and applied to a greater number of pathologies, especially in mitral valve surgeries, as it obtains results comparable to those of conventional techniques while entailing lower surgical trauma and shorter recovery time. MICS requiring one-lung ventilation has been associated to the appearance of unilateral pulmonary edema (UPE), which is a potentially serious complication. The objective is determining the incidence of UPE after mitral MICS and its development associated factors. Material and methods: Observational descriptive and single-center study analyzing data from patients undergoing mitral valve MICS (right mini-thoracotomy) consecutively collected between the years 2015 and 2017. Results: A total of 93 patients were included and 26 presented UPE. The most common complications after mitral valve MICS were atrial fibrillation (38.7%), UPE (28%) and transient and/or definitive second- or third-degree auriculoventricular block (19.4%). The UPE group had longer ICU stay (3.3±8.0 vs. 1.84±2.23 days) and longer total hospitalization length-of-stay (15.5±34.7 vs. 10.6±7.5 days). The mortality in the UPE group was 3.9%. A significant association was found between the following collected variables and the development of postoperative UPE: preoperative baseline pulse oximetry, preoperative use of ACE inhibitors, postoperative atrial fibrillation and 24 first-hours cumulative chest tube drainage volume on the first 24h. Conclusions: The incidence of UPE is high and its appearance is associated with a longer ICU and total length of stay. More studies are required to understand its pathophysiology and apply measures to help decreasing its appearance.(AU)

Out-of-field doses for scanning proton radiotherapy of shallowly located paediatric tumours-a comparison of range shifter and 3D printed compensator.

The lowest possible energy of proton scanning beam in cyclotron proton therapy facilities is typically between 60 and 100 MeV. Treatment of superficial lesions requires a pre-absorber to deliver doses to shallower volumes. In most of the cases a range shifter (RS) is used, but as an alternative solution, a patient-specific 3D printed proton beam compensator (BC) can be applied. A BC enables further reduction of the air gap and consequently reduction of beam scattering. Such pre-absorbers are additional sources of secondary radiation. The aim of this work was the comparison of RS and BC with respect to out-of-field doses for a simulated treatment of superficial paediatric brain tumours. EURADOS WG9 performed comparative measurements of scattered radiation in the Proteus C-235 IBA facility (Cyclotron Centre Bronowice at the Institute of Nuclear Physics, CCB IFJ PAN, Kraków, Poland) using two anthropomorphic phantoms-5 and 10 yr old-for a superficial target in the brain. Both active detectors located inside the therapy room, and passive detectors placed inside the phantoms were used. Measurements were supplemented by Monte Carlo simulation of the radiation transport. For the applied 3D printed pre-absorbers, out-of-field doses from both secondary photons and neutrons were lower than for RS. Measurements with active environmental dosimeters at five positions inside the therapy room indicated that the RS/BC ratio of the out-of-field dose was also higher than one, with a maximum of 1.7. Photon dose inside phantoms leads to higher out-of-field doses for RS than BC to almost all organs with the highest RS/BC ratio 12.5 and 13.2 for breasts for 5 and 10 yr old phantoms, respectively. For organs closest to the isocentre such as the thyroid, neutron doses were lower for BC than RS due to neutrons moderation in the target volume, but for more distant organs like bladder-conversely-lower doses for RS than BC were observed. The use of 3D printed BC as the pre-absorber placed in the near vicinity of patient in the treatment of superficial tumours does not result in the increase of secondary radiation compared to the treatment with RS, placed far from the patient.

Study of the intracellular nanoparticle-based radiosensitization mechanisms in F98 glioma cells treated with charged particle therapy through synchrotron-based infrared microspectroscopy.

The use of nanoparticles (NP) as dose enhancers in radiotherapy (RT) is a growing research field. Recently, the use of NP has been extended to charged particle therapy in order to improve the performance in radioresistant tumors. However, the biological mechanisms underlying the synergistic effects involved in NP-RT approaches are not clearly understood. Here, we used the capabilities of synchrotron-based Fourier Transform Infrared Microspectroscopy (SR-FTIRM) as a bio-analytical tool to elucidate the NP-induced cellular damage at the molecular level and at a single-cell scale. F98 glioma cells doped with AuNP and GdNP were irradiated using several types of medical ion beams (proton, helium, carbon and oxygen). Differences in cell composition were analyzed in the nucleic acids, protein and lipid spectral regions using multivariate methods (Principal Component Analysis, PCA). Several NP-induced cellular modifications were detected, such as conformational changes in secondary protein structures, intensity variations in the lipid CHx stretching bands, as well as complex DNA rearrangements following charged particle therapy irradiations. These spectral features seem to be correlated with the already shown enhancement both in the DNA damage response and in the reactive oxygen species (ROS) production by the NP, which causes cell damage in the form of protein, lipid, and/or DNA oxidations. Vibrational features were NP-dependent due to the NP heterogeneous radiosensitization capability. Our results provided new insights into the molecular changes in response to NP-based RT treatments using ion beams, and highlighted the relevance of SR-FTIRM as a useful and precise technique for assessing cell response to innovative radiotherapy approaches.

A synchrotron-based infrared microspectroscopy study on the cellular response induced by gold nanoparticles combined with X-ray irradiations on F98 and U87-MG glioma cell lines.

The inclusion of nanoparticles (NP) in radiotherapy has been shown to increase the damaging effect on tumor cells. However, the mechanisms of action of NP combined with radiotherapy, and the influence of NP parameters and cell type on their radiosensitization capability at molecular and cellular levels still remain unclear. Gold NP (AuNP) have become particularly popular due to their multiple advantages. Within this context, our research work aimed to study the biochemical radiosensitization capacity of F98 and U87-MG glioma cell lines to 1.9 nm AuNP combined with X-ray irradiation. For this purpose, synchrotron-based infrared microspectroscopy (SR-FTIRM) was used as a powerful tool for biochemical composition and treatment response assessment of cells at a single-cell level. SR-FTIRM data, supported by multivariate analysis, revealed clear AuNP-induced changes in the DNA, protein and lipid spectral regions. The AuNP-related biochemical alterations appear prior to the irradiation, which gave us a first indication on the AuNP radiosensitization action. Biochemical modifications induced by the AuNP in the presence of radiotherapy irradiations include enhanced conformational changes in the protein secondary structures, variations in the intensity and position in the phosphodiester bands, and changes in the CH2 and CH3 stretching modes. These changes are better manifested at 24 hours post-irradiation time. SR-FTIRM results showed a clear heterogeneity in the biochemical cell response, probably due to the distinct cell-NP interactions and thus, to different DNA damage and cell death processes.

COMPARISON OF RESPONSE OF PASSIVE DOSIMETRY SYSTEMS IN SCANNING PROTON RADIOTHERAPY-A STUDY USING PAEDIATRIC ANTHROPOMORPHIC PHANTOMS.

Proton beam therapy has advantages in comparison to conventional photon radiotherapy due to the physical properties of proton beams (e.g. sharp distal fall off, adjustable range and modulation). In proton therapy, there is the possibility of sparing healthy tissue close to the target volume. This is especially important when tumours are located next to critical organs and while treating cancer in paediatric patients. On the other hand, the interactions of protons with matter result in the production of secondary radiation, mostly neutrons and gamma radiation, which deposit their energy at a distance from the target. The aim of this study was to compare the response of different passive dosimetry systems in mixed radiation field induced by proton pencil beam inside anthropomorphic phantoms representing 5 and 10 years old children. Doses were measured in different organs with thermoluminescent (MTS-7, MTS-6 and MCP-N), radiophotoluminescent (GD-352 M and GD-302M), bubble and poly-allyl-diglycol carbonate (PADC) track detectors. Results show that RPL detectors are the less sensitive for neutrons than LiF TLDs and can be applied for in-phantom dosimetry of gamma component. Neutron doses determined using track detectors, bubble detectors and pairs of MTS-7/MTS-6 are consistent within the uncertainty range. This is the first study dealing with measurements on child anthropomorphic phantoms irradiated by a pencil scanning beam technique.

Proton minibeam radiation therapy: Experimental dosimetry evaluation.

PURPOSE: Proton minibeam radiation therapy (pMBRT) is a new radiotherapy (RT) approach that allies the inherent physical advantages of protons with the normal tissue preservation observed when irradiated with submillimetric spatially fractionated beams. This dosimetry work aims at demonstrating the feasibility of the technical implementation of pMBRT. This has been performed at the Institut Curie - Proton Therapy Center in Orsay. METHODS: Proton minibeams (400 and 700 µm-width) were generated by means of a brass multislit collimator. Center-to-center distances between consecutive beams of 3200 and 3500 µm, respectively, were employed. The (passive scattered) beam energy was 100 MeV corresponding to a range of 7.7 cm water equivalent. Absolute dosimetry was performed with a thimble ionization chamber (IBA CC13) in a water tank. Relative dosimetry was carried out irradiating radiochromic films interspersed in a IBA RW3 slab phantom. Depth dose curves and lateral profiles at different depths were evaluated. Peak-to-valley dose ratios (PVDR), beam widths, and output factors were also assessed as a function of depth. RESULTS: A pattern of peaks and valleys was maintained in the transverse direction with PVDR values decreasing as a function of depth until 6.7 cm. From that depth, the transverse dose profiles became homogeneous due to multiple Coulomb scattering. Peak-to-valley dose ratio values extended from 8.2 ± 0.5 at the phantom surface to 1.08 ± 0.06 at the Bragg peak. This was the first time that dosimetry in such small proton field sizes was performed. Despite the challenge, a complete set of dosimetric data needed to guide the first biological experiments was achieved. CONCLUSIONS: pMBRT is a novel strategy in order to reduce the side effects of RT. This works provides the experimental proof of concept of this new RT method: clinical proton beams might allow depositing a (high) uniform dose in a brain tumor located in the center of the brain (7.5 cm depth, the worst scenario), while a spatial fractionation of the dose is retained in the normal tissues in the beam path, potentially leading to a gain in tissue sparing. This is the first complete experimental implementation of this promising technique. Biological experiments are needed in order to confirm the clinical potential of pMBRT.

Evaluation of the local dose enhancement in the combination of proton therapy and nanoparticles.

PURPOSE: The outcome of radiotherapy can be further improved by combining irradiation with dose enhancers such as high-Z nanoparticles. Since 2004, spectacular results have been obtained when low-energy x-ray irradiations have been combined with nanoparticles. Recently, the same combination has been explored in hadron therapy. In vitro studies have shown a significant amplification of the biological damage in tumor cells charged with nanoparticles and irradiated with fast ions. This has been attributed to the increase in the ionizations and electron emissions induced by the incident ions or the electrons in the secondary tracks on the high-Z atoms, resulting in a local energy deposition enhancement. However, this subject is still a matter of controversy. Within this context, the main goal of the authors' work was to provide new insights into the dose enhancement effects of nanoparticles in proton therapy. METHODS: For this purpose, Monte Carlo calculations (gate/geant4 code) were performed. In particular, the geant4-DNA toolkit, which allows the modeling of early biological damages induced by ionizing radiation at the DNA scale, was used. The nanometric radial energy distributions around the nanoparticle were studied, and the processes (such as Auger deexcitation or dissociative electron attachment) participating in the dose deposition of proton therapy treatments in the presence of nanoparticles were evaluated. It has been reported that the architecture of Monte Carlo calculations plays a crucial role in the assessment of nanoparticle dose enhancement and that it may introduce a bias in the results or amplify the possible final dose enhancement. Thus, a dosimetric study of different cases was performed, considering Au and Gd nanoparticles, several nanoparticle sizes (from 4 to 50 nm), and several beam configurations (source-nanoparticle distances and source sizes). RESULTS: This Monte Carlo study shows the influence of the simulations' parameters on the local dose enhancement and how more realistic configurations lead to a negligible increase of local energy deposition. The obtained dose enhancement factor was up to 1.7 when the source was located at the nanoparticle surface. This dose enhancement was reduced when the source was located at further distances (i.e., in more realistic situations). Additionally, no significant increase in the dissociative electron attachment processes was observed. CONCLUSIONS: The authors' results indicate that physical effects play a minor role in the amplification of damage, as a very low dose enhancement or increase of dissociative electron attachment processes is observed when the authors get closer to more realistic simulations. Thus, other effects, such as biological or chemical processes, may be mainly responsible for the enhanced radiosensibilization observed in biological studies. However, more biological studies are needed to verify this hypothesis.

Spatial fractionation of the dose using neon and heavier ions: A Monte Carlo study.

PURPOSE: This work explores a new radiation therapy approach which might trigger a renewed use of neon and heavier ions to treat cancers. These ions were shown to be extremely efficient in radioresistant tumor killing. Unfortunately, the efficient region also extends into the normal tissue in front of the tumor. The strategy the authors propose is to profit from the well-established sparing effect of thin spatially fractionated beams, so that the impact on normal tissues might be minimized while a high tumor control is achieved. The main goal of this work is to provide a proof of concept of this new approach. With that aim, a dosimetric study was carried out as a first step to evaluate the interest of further explorations of this avenue. METHODS: The gate/geant4 v.6.1 Monte Carlo simulation platform was employed to simulate arrays of rectangular minibeams (700 µm × 2 cm) of four ions (Ne, Si, Ar, and Fe). The irradiations were performed with a 2 cm-long spread-out Bragg peak centered at 7 cm-depth. Dose distributions in a water phantom were scored considering two minibeams center-to-center distances: 1400 and 3500 µm. Peak and valley doses, peak-to-valley dose ratios (PVDRs), beam penumbras, and relative contribution of nuclear fragments and electromagnetic processes were assessed as figures of merit. In addition, the type and proportion of the secondary nuclear fragments were evaluated in both peak and valley regions. RESULTS: Extremely high PVDR values (>100) and low valley doses were obtained. The higher the atomic number (Z) of the primary ion is, the lower the valleys and the narrower the penumbras. Although the yield of secondary nuclear products increases with Z, the actual dose being deposited by the secondary nuclear fragments in the valleys starts to be the dominant contribution at deeper points, helping in the sparing of proximal normal tissues. Additionally, a wider center-to-center distance leads to a minimized contribution of heavier secondary fragments in valleys. CONCLUSIONS: The computed dose distributions suggest that a spatial fractionation of the dose combined to the use of submillimetric field sizes might allow profiting from the high efficiency of neon and heavier ions for the treatment of radioresistant tumors, while preserving normal tissues. The authors' results support the further exploration of this avenue. Next steps include the realization of biological experiment to confirm the shifting of normal tissue complication probability curves.

Technical note: Implementation of biological washout processes within GATE/GEANT4--a Monte Carlo study in the case of carbon therapy treatments.

PURPOSE: The imaging of positron emitting isotopes produced during patient irradiation is the only in vivo method used for hadrontherapy dose monitoring in clinics nowadays. However, the accuracy of this method is limited by the loss of signal due to the metabolic decay processes (biological washout). In this work, a generic modeling of washout was incorporated into the GATE simulation platform. Additionally, the influence of the washout on the ß(+) activity distributions in terms of absolute quantification and spatial distribution was studied. METHODS: First, the irradiation of a human head phantom with a (12)C beam, so that a homogeneous dose distribution was achieved in the tumor, was simulated. The generated (11)C and (15)O distribution maps were used as ß(+) sources in a second simulation, where the PET scanner was modeled following a detailed Monte Carlo approach. The activity distributions obtained in the presence and absence of washout processes for several clinical situations were compared. RESULTS: Results show that activity values are highly reduced (by a factor of 2) in the presence of washout. These processes have a significant influence on the shape of the PET distributions. Differences in the distal activity falloff position of 4 mm are observed for a tumor dose deposition of 1 Gy (Tini = 0 min). However, in the case of high doses (3 Gy), the washout processes do not have a large effect on the position of the distal activity falloff (differences lower than 1 mm). The important role of the tumor washout parameters on the activity quantification was also evaluated. CONCLUSIONS: With this implementation, GATE/GEANT4 is the only open-source code able to simulate the full chain from the hadrontherapy irradiation to the PET dose monitoring including biological effects. Results show the strong impact of the washout processes, indicating that the development of better models and measurement of biological washout data are essential.

Dosimetric evaluation of new approaches in GRID therapy using nonconventional radiation sources.

PURPOSE: Spatial fractionation of the dose has proven to be a promising approach to increase the tolerance of healthy tissue, which is the main limitation of radiotherapy. A good example of that is GRID therapy, which has been successfully used in the management of large tumors with low toxicity. The aim of this work is to explore new avenues using nonconventional sources: GRID therapy by using kilovoltage (synchrotron) x-rays, the use of very high-energy electrons, and proton GRID therapy. They share in common the use of the smallest possible grid sizes in order to exploit the dose-volume effects. METHODS: Monte Carlo simulations (penelope/peneasy and geant4/GATE codes) were used as a method to study dose distributions resulting from irradiations in different configurations of the three proposed techniques. As figure of merit, percentage (peak and valley) depth dose curves, penumbras, and central peak-to-valley dose ratios (PVDR) were evaluated. As shown in previous biological experiments, high PVDR values are requested for healthy tissue sparing. A superior tumor control may benefit from a lower PVDR. RESULTS: High PVDR values were obtained in the healthy tissue for the three cases studied. When low energy photons are used, the treatment of deep-seated tumors can still be performed with submillimetric grid sizes. Superior PVDR values were reached with the other two approaches in the first centimeters along the beam path. The use of protons has the advantage of delivering a uniform dose distribution in the tumor, while healthy tissue benefits from the spatial fractionation of the dose. In the three evaluated techniques, there is a net reduction in penumbra with respect to radiosurgery. CONCLUSIONS: The high PVDR values in the healthy tissue and the use of small grid sizes in the three presented approaches might constitute a promising alternative to treat tumors with such spatially fractionated radiotherapy techniques. The dosimetric results presented here support the interest of performing radiobiology experiments in order to evaluate these new avenues.

Importancia de la ecocardiografía transesofágica intraoperatoria en la decisión quirúrgica en cirugía cardiaca / The importance of intraoperative transesophageal echocardiography in the surgical decision in cardiac surgery

Objetivo. Determinar la importancia de la ecocardiografía transesofágica (ECOTE) intraoperatoria en la decisión quirúrgica en pacientes intervenidos de cirugía cardiaca. Pacientes y método. Estudio prospectivo observacional en pacientes de cirugía cardiaca intervenidos desde enero de 2009 hasta mayo de 2012, a los que se monitorizó con ECOTE por el anestesiólogo responsable. Los datos recogidos fueron: 1) tipo de cirugía; 2) diagnóstico ecocardiográfico preoperatorio (ECO basal); 3) diagnóstico ecocardiográfico antes de entrar en circulación extracorpórea (CEC) (ECOTE pre-CEC); 4) si había diferencias entre la ECO basal y la ECOTE pre-CEC (hallazgo nuevo pre-CEC) y si estas diferencias modificaban la cirugía planeada, y 5) diagnóstico ecocardiográfico después de la desconexión de CEC (hallazgo no esperado pos-CEC) y si estos hallazgos ecocardiográficos pos-CEC hacían reinstaurarla. Para el análisis de datos se utilizó el programa de software SPSS(R). Resultados. El total de pacientes estudiados fue de 1.273; la monitorización con ECOTE mostró «hallazgos nuevos pre-CEC» en 98 pacientes (7,7%) y en 43,8% de estos modificó la cirugía programada; de estos hallazgos, los más frecuentes fueron alteraciones de la válvula mitral que no habían sido diagnosticadas, lo que determinó la sustitución o reparación de la misma que no estaba programada. La incidencia de «hallazgos no esperados pos-CEC» fue del 6,2% (79 pacientes), y de estos, en el 46,8% se requirió reinstaurar la CEC y modificar la cirugía realizada. Las reparaciones valvulares fallidas y las prótesis valvulares disfuncionantes fueron las causas principales que motivaron la reentrada en CEC. En los 42 pacientes restantes, con «hallazgos no esperados pos-CEC», no hubo cambios en la conducta quirúrgica, ya que se consideró que el hallazgo ecocardiográfico no era lo suficientemente significativo como para reinstaurar la CEC y revisar o cambiar el procedimiento quirúrgico. Conclusión. En cirugía cardiaca, la monitorización intraoperatoria con ECOTE por el anestesiólogo aporta información importante antes y después de la CEC que modificó el manejo quirúrgico (AU)

Objective. To determine the importance of intraoperative transesophageal echocardiography (IOTEE) in the surgical decision in patients undergoing cardiac surgery. Patients and method. Prospective observational study of patients undergoing cardiac surgery from January 2009 to May 2012, which was monitored with IOTEE by the anesthesiologist in charge. The data collected were: 1) type of surgery; 2) preoperative echocardiographic diagnosis (baseline ECHO); 3) echocardiographic diagnosis before entering cardiopulmonary bypass (CPB) (pre-CPB IOTEE); 4) any differences between the baseline ECHO and the pre-CPB IOTEE (new pre-CPB finding) and whether these differences modified the planned surgery, and 5) echocardiographic diagnosis after disconnection of CPB (unexpected post-CPB finding) and whether these post-CPB echocardiographic findings led to reinstating it. The software program SPSS(R) was used for data analysis. Results. The total number of patients studied was 1,273. Monitoring with IOTEE showed 'new pre-CPB' findings in 98 patients (7.7%), and 43.8% of these led to a change in the scheduled surgery. Of these findings, the most frequent were abnormalities of the mitral valve that had not been diagnosed, and which led to a replacement or repair that had not been scheduled. The incidence of 'unexpected post-CPB findings' was 6.2% (79 patients), and 46.8% of those required reinstating the CPB and modifying the surgery performed. The failed valve repairs and dysfunctional valve prostheses were the main causes that led to re-entry into CPB. In the remaining 42 patients, with 'unexpected post-CPB findings', there were no changes in the surgical procedure as the echocardiographic findings were not considered to be significant enough to re-establish CPB and revise or change the surgical procedure. Conclusion. Intraoperative monitoring with IOTEE by the anesthesiologist during surgery provides important information before and after the CPB that resulted in modifying surgical management (AU)

[The importance of intraoperative transesophageal echocardiography in the surgical decision in cardiac surgery]. / Importancia de la ecocardiografía transesofágica intraoperatoria en la decisión quirúrgica en cirugía cardiaca.

OBJECTIVE: To determine the importance of intraoperative transesophageal echocardiography (IOTEE) in the surgical decision in patients undergoing cardiac surgery. PATIENTS AND METHOD: Prospective observational study of patients undergoing cardiac surgery from January 2009 to May 2012, which was monitored with IOTEE by the anesthesiologist in charge. The data collected were: 1) type of surgery; 2) preoperative echocardiographic diagnosis (baseline ECHO); 3) echocardiographic diagnosis before entering cardiopulmonary bypass (CPB) (pre-CPB IOTEE); 4) any differences between the baseline ECHO and the pre-CPB IOTEE (new pre-CPB finding) and whether these differences modified the planned surgery, and 5) echocardiographic diagnosis after disconnection of CPB (unexpected post-CPB finding) and whether these post-CPB echocardiographic findings led to reinstating it. The software program SPSS(®) was used for data analysis. RESULTS: The total number of patients studied was 1,273. Monitoring with IOTEE showed "new pre-CPB" findings in 98 patients (7.7%), and 43.8% of these led to a change in the scheduled surgery. Of these findings, the most frequent were abnormalities of the mitral valve that had not been diagnosed, and which led to a replacement or repair that had not been scheduled. The incidence of "unexpected post-CPB findings" was 6.2% (79 patients), and 46.8% of those required reinstating the CPB and modifying the surgery performed. The failed valve repairs and dysfunctional valve prostheses were the main causes that led to re-entry into CPB. In the remaining 42 patients, with "unexpected post-CPB findings", there were no changes in the surgical procedure as the echocardiographic findings were not considered to be significant enough to re-establish CPB and revise or change the surgical procedure. CONCLUSION: Intraoperative monitoring with IOTEE by the anesthesiologist during surgery provides important information before and after the CPB that resulted in modifying surgical management.

Minibeam radiation therapy for the management of osteosarcomas: a Monte Carlo study.

PURPOSE: Minibeam radiation therapy (MBRT) exploits the well-established tissue-sparing effect provided by the combination of submillimetric field sizes and a spatial fractionation of the dose. The aim of this work is to evaluate the feasibility and potential therapeutic gain of MBRT, in comparison with conventional radiotherapy, for osteosarcoma treatments. METHODS: Monte Carlo simulations (PENELOPE/penEasy code) were used as a method to study the dose distributions resulting from MBRT irradiations of a rat femur and a realistic human femur phantoms. As a figure of merit, peak and valley doses and peak-to-valley dose ratios (PVDR) were assessed. Conversion of absorbed dose to normalized total dose (NTD) was performed in the human case. Several field sizes and irradiation geometries were evaluated. RESULTS: It is feasible to deliver a uniform dose distribution in the target while the healthy tissue benefits from a spatial fractionation of the dose. Very high PVDR values (⩾20) were achieved in the entrance beam path in the rat case. PVDR values ranged from 2 to 9 in the human phantom. NTD(2.0) of 87 Gy might be reached in the tumor in the human femur while the healthy tissues might receive valley NTD(2.0) lower than 20 Gy. The doses in the tumor and healthy tissues might be significantly higher and lower than the ones commonly delivered used in conventional radiotherapy. CONCLUSIONS: The obtained dose distributions indicate that a gain in normal tissue sparing might be expected. This would allow the use of higher (and potentially curative) doses in the tumor. Biological experiments are warranted.

Manejo perioperatorio de la fibrilación auricular / Perioperative management of atrial fibrillation

La fibrilación auricular es una complicación frecuente en el periodo perioperatorio, y cuando aparece se incrementa el riesgo de morbimortalidad perioperatoria debido a ACV, tromboembolismo, fallo cardiaco, IAM, hemorragia debida a anticoagulación y reingresos hospitalarios. En el presente artículo se recogen las recomendaciones para el manejo de la fibrilación auricular perioperatoria basándose en las últimas Guías de Práctica Clínica de la fibrilación auricular publicadas por la Sociedad Europea de Cardiología y la Sociedad Española de Cardiología, prestando atención tanto a su optimización preoperatoria, como al manejo del episodio agudo perioperatorio. En este sentido se incluyen las últimas recomendaciones para control de la frecuencia cardiaca, control del ritmo y anticoagulación (AU)

Atrial fibrillation is a frequent complication in the perioperative period. When it appears there is an increased risk of perioperative morbidity due to stroke, thromboembolism, cardiac arrest, myocardial infarction, anticoagulation haemorrhage, and hospital readmissions. The current article focuses on the recommendations for the management of perioperative atrial fibrillation based on the latest Clinical Practice Guidelines on atrial fibrillation by the European Society of Cardiology and the Spanish Society of Cardiology. This article pays special attention to the preoperative management, as well as to the acute perioperative episode. For this reason, the latest recommendations for the control of cardiac frequency, antiarrhythmic treatment and anticoagulation are included (AU)

Monte Carlo-based dose calculation engine for minibeam radiation therapy.

Minibeam radiation therapy (MBRT) is an innovative radiotherapy approach based on the well-established tissue sparing effect of arrays of quasi-parallel micrometre-sized beams. In order to guide the preclinical trials in progress at the European Synchrotron Radiation Facility (ESRF), a Monte Carlo-based dose calculation engine has been developed and successfully benchmarked with experimental data in anthropomorphic phantoms. Additionally, a realistic example of treatment plan is presented. Despite the micron scale of the voxels used to tally dose distributions in MBRT, the combination of several efficiency optimisation methods allowed to achieve acceptable computation times for clinical settings (approximately 2 h). The calculation engine can be easily adapted with little or no programming effort to other synchrotron sources or for dose calculations in presence of contrast agents.

[Perioperative management of atrial fibrillation]. / Manejo perioperatorio de la fibrilación auricular.

Atrial fibrillation is a frequent complication in the perioperative period. When it appears there is an increased risk of perioperative morbidity due to stroke, thromboembolism, cardiac arrest, myocardial infarction, anticoagulation haemorrhage, and hospital readmissions. The current article focuses on the recommendations for the management of perioperative atrial fibrillation based on the latest Clinical Practice Guidelines on atrial fibrillation by the European Society of Cardiology and the Spanish Society of Cardiology. This article pays special attention to the preoperative management, as well as to the acute perioperative episode. For this reason, the latest recommendations for the control of cardiac frequency, antiarrhythmic treatment and anticoagulation are included.

Monte Carlo-based treatment planning system calculation engine for microbeam radiation therapy.

PURPOSE: Microbeam radiation therapy (MRT) is a synchrotron radiotherapy technique that explores the limits of the dose-volume effect. Preclinical studies have shown that MRT irradiations (arrays of 25-75-µm-wide microbeams spaced by 200-400 µm) are able to eradicate highly aggressive animal tumor models while healthy tissue is preserved. These promising results have provided the basis for the forthcoming clinical trials at the ID17 Biomedical Beamline of the European Synchrotron Radiation Facility (ESRF). The first step includes irradiation of pets (cats and dogs) as a milestone before treatment of human patients. Within this context, accurate dose calculations are required. The distinct features of both beam generation and irradiation geometry in MRT with respect to conventional techniques require the development of a specific MRT treatment planning system (TPS). In particular, a Monte Carlo (MC)-based calculation engine for the MRT TPS has been developed in this work. Experimental verification in heterogeneous phantoms and optimization of the computation time have also been performed. METHODS: The penelope/penEasy MC code was used to compute dose distributions from a realistic beam source model. Experimental verification was carried out by means of radiochromic films placed within heterogeneous slab-phantoms. Once validation was completed, dose computations in a virtual model of a patient, reconstructed from computed tomography (CT) images, were performed. To this end, decoupling of the CT image voxel grid (a few cubic millimeter volume) to the dose bin grid, which has micrometer dimensions in the transversal direction of the microbeams, was performed. Optimization of the simulation parameters, the use of variance-reduction (VR) techniques, and other methods, such as the parallelization of the simulations, were applied in order to speed up the dose computation. RESULTS: Good agreement between MC simulations and experimental results was achieved, even at the interfaces between two different media. Optimization of the simulation parameters and the use of VR techniques saved a significant amount of computation time. Finally, parallelization of the simulations improved even further the calculation time, which reached 1 day for a typical irradiation case envisaged in the forthcoming clinical trials in MRT. An example of MRT treatment in a dog's head is presented, showing the performance of the calculation engine. CONCLUSIONS: The development of the first MC-based calculation engine for the future TPS devoted to MRT has been accomplished. This will constitute an essential tool for the future clinical trials on pets at the ESRF. The MC engine is able to calculate dose distributions in micrometer-sized bins in complex voxelized CT structures in a reasonable amount of time. Minimization of the computation time by using several approaches has led to timings that are adequate for pet radiotherapy at synchrotron facilities. The next step will consist in its integration into a user-friendly graphical front-end.

Scatter factors assessment in microbeam radiation therapy.

PURPOSE: The success of the preclinical studies in Microbeam Radiation Therapy (MRT) paved the way to the clinical trials under preparation at the Biomedical Beamline of the European Synchrotron Radiation Facility. Within this framework, an accurate determination of the deposited dose is crucial. With that aim, the scatter factors, which translate the absolute dose measured in reference conditions (2 × 2 cm(2) field size at 2 cm-depth in water) to peak doses, were assessed. METHODS: Monte Carlo (MC) simulations were performed with two different widely used codes, PENELOPE and GEANT4, for the sake of safety. The scatter factors were obtained as the ratio of the doses that are deposited by a microbeam and by a field of reference size, at the reference depth. The calculated values were compared with the experimental data obtained by radiochromic (ISP HD-810) films and a PTW 34070 large area chamber. RESULTS: The scatter factors for different microbeam field sizes assessed by the two MC codes were in agreement and reproduced the experimental data within uncertainty bars. Those correction factors were shown to be non-negligible for the future MRT clinical settings: an average 30% lower dose was deposited by a 50 µm microbeam with respect to the reference conditions. CONCLUSIONS: For the first time, the scatter factors in MRT were systematically studied. They constitute an essential key to deposit accurate doses in the forthcoming clinical trials in MRT. The good agreement between the different calculations and the experimental data confirms the reliability of this challenging micrometric dose estimation.