Validation of rectal sparing throughout the course of proton therapy treatment in prostate cancer patients treated with SpaceOAR®.

The purpose of this study was to investigate the consistency of rectal sparing using multiple periodic quality assurance computerized tomography imaging scans (QACT) obtained during the course of proton therapy for patients with prostate cancer treated with a hydrogel spacer. Forty-one low- and intermediate-risk prostate cancer patients treated with image-guided proton therapy with rectal spacer hydrogel were analyzed. To assess the reproducibility of rectal sparing with the hydrogel spacer, three to four QACTs were performed for each patient on day 1 and during weeks 1, 3, and 5 of treatment. The treatment plan was calculated on the QACT and the rectum V90%, V75%, V65%, V50%, and V40% were evaluated. For the retrospective analysis, we evaluated each QACT and compared it to the corresponding treatment planning CT (TPCT), to determine the average change in rectum DVH points. We were also interested in how many patients exceeded an upper rectum V90% threshold on a QACT. Finally, we were interested in a correlation between rectum volume and V90%. On each QACT, if the rectum V90% exceeded the upper threshold of 6%, the attending physician was notified and the patient was typically prescribed additional stool softeners or laxatives and reminded of dietary compliance. In all cases of the rectum V90% exceeding the threshold, the patient had increased gas and/or stool, compared to the TPCT. On average, the rectum V90% calculated on the QACT was 0.81% higher than that calculated on the TPCT. The average increase in V75%, V65%, V50%, and V40% on the QACT was 1.38%, 1.59%, 1.87%, and 2.17%, respectively. The rectum V90% was within ± 1% of the treatment planning dose in 71.2% of the QACTs, and within ± 5% in 93.2% of the QACTs. The 6% threshold for rectum V90% was exceeded in 7 out of 144 QACTs (4.8%), identified in 5 of the 41 patients. We evaluated the average rectum V90% across all QACTs for each of these patients, and it was found that the rectum V90% never exceeded 6%. 53% of the QACTs had a rectum volume within 5 cm3 of the TPCT volume, 68% were within 10 cm3. We found that patients who exceeded the threshold on one or more QACTs had a lower TPCT rectal volume than the overall average. By extrapolating patient anatomy from three to four QACT scans, we have shown that the use of hydrogel in conjunction with our patient diet program and use of stool softeners is effective in achieving consistent rectal sparing in patients undergoing proton therapy.

A comparison between hydrogel spacer and endorectal balloon: An analysis of intrafraction prostate motion during proton therapy.

The purpose of this study was to evaluate intrafraction prostate motion in patients treated with proton therapy and an endorectal balloon or a hydrogel spacer using orthogonal x-rays acquired before and after each treatment field. This study evaluated 10 patients (662 fields throughout treatment) treated daily with an endorectal balloon (ERB) and 16 patients (840 fields throughout treatment) treated with a hydrogel spacer (GEL) without an ERB. Patient shifts were recorded before and after each treatment field, correlated with a treatment time, using x-ray imaging and implanted fiducial alignment. For each shift, recorded in X, Y, and Z, a 3D vector was calculated to determine the positional change. There was a statistically significant difference in the mean vector shift between ERB (0.06 cm) and GEL (0.09 cm), (P < 0.001). The mean includes a large number of zero shifts, but the smallest non-zero shift recorded was 0.2 cm. The largest shifts were, on average, in the Z direction (anterior to posterior). The average Z shift was +0.02 cm for both ERB and GEL. There was no statistical difference between ERB and GEL for shifts greater than 0.3 cm (P = 0.13) or greater than 0.5 cm (P = 0.36). For treatment times between 5 and 9 min, a majority of shifts were less than 0.2 cm, 85.9% for ERB and 73.2% for GEL. There was a significant positive correlation between the vector shifts and field time for both ERB (r = 0.2, P < 0.001) and GEL (r = 0.07, P < 0.04). We have shown that prostate motion is clinically comparable between an ERB and a hydrogel spacer, and the time dependencies are similar. A large majority of shifts for both ERB and hydrogel are well within a typical robust planning margin. For GEL patients, we chose to maintain slightly larger planning margins than for ERB due to already improved rectal sparing with GEL.

Assessment of Tissue Oxygenation and Radiation Dermatitis Pre-, During, and Post-Radiation Therapy in Breast Cancer Patients.

Over 95% of breast cancer patients treated with radiation therapy (RT) undergo an adverse skin reaction known as radiation dermatitis (RD). Assessment of severity or grading of RD is clinically visual and hence subjective. Our objective is to determine sub-clinical tissue oxygenation (oxygen saturation) changes in response to RT in breast cancer patients using near-infrared spectroscopic imaging and correlate these changes to RD grading. A 4-8 week longitudinal pilot imaging study was carried out on 10 RT-treated breast cancer patients. Non-contact near-infrared spectroscopic (NIRS) imaging was performed on the irradiated ipsilateral and the contralateral breast/chest wall, axilla and lower neck regions before RT, across the weeks of RT, and during follow-up after RT ended. Significant changes (p < 0.05) in oxygen saturation (StO2) of irradiated and contralateral breast/chest wall and axilla regions were observed across weeks of RT. The overall drop in StO2 was negatively correlated to RD scaling (in 7 out of 9 cases) and was higher in the irradiated regions when compared to its contralateral region. Differences in the pre-RT StO2 between ipsilateral and contralateral chest wall is a potential predictor of the severity of RD. The subclinical recovery of StO2 to its original state was longer than the visual recovery in RD grading scale, as observed from the post-RT assessment of tissue oxygenation.

Evaluation of a prospective radiation oncology departmental team review process using standardized simulation directives.

INTRODUCTION: The primary objective of this study is to evaluate the utility and value of an institutional, multi-disciplinary radiation oncology team review process prior to radiotherapy (RT) simulation. METHODS: Over a period of 3 months and through an iterative team-based process, a standardized simulation requisition directive (SSRD) was developed, piloted, modified, and subsequently implemented for all patients treated with external beam RT at a single tertiary care institution from January to December 2020. The SSRDs were reviewed at a daily multi-disciplinary radiation oncology team review conference; modifications consequential to the review were prospectively recorded in a quality database. RESULTS: 1500 consecutive SSRDs were prospectively reviewed for this study. 397 modifications on 290 (19.3%) SSRDs were recorded and parsed into 5 main categories and 18 subcategories. The most common modifications resulted from changes in immobilization device (n = 88, 22.2%), RT care path (n = 56, 14.1%), and arm positioning (n = 43, 10.8%). On univariate analysis, modifications were associated with RT intent, scan parameters, tumor site, and consultation type. An increased rate modifications was observed for patients had telemedicine consults (n = 101, 22.7%) compared to in-person consultations (n = 189, 17.9%) (p = 0.032). Using logistic regression analysis, there was also a statistically significant relationship between postoperative RT delivery and modification rates (OR: 2.913, 95% CI: 1.014-8.372) (p = 0.0126). Overall, only 14 patients (0.9%) needed re-simulation during the entire study period. CONCLUSIONS: Prospective multi-disciplinary radiation oncology team review prior to simulation identifies actionable change in approximately 19% of procedures, and results in an extremely low rate (<1%) of re-simulation. As departmental processes transition to virtual platforms, thorough attention is needed to identify patients at higher risk of simulation modifications.

Expanding the Utilization of Rectal Spacer Hydrogel for Larger Prostate Glands (>80 cc): Feasibility and Dosimetric Outcomes.

PURPOSE: The Hydrogel Spacer Prospective Randomized Pivotal Trial achieved mean rectoprostatic spacing of 12.6 mm resulting in lowering of rectal V70 from 12.4% (without spacer) to 3.3% (with spacer) in patients with glands up to 80 cm3. The value of this approach in patients with larger glands is inadequately established. This study assesses the feasibility and dosimetric outcomes of perirectal spacing in patients with prostate cancer with larger glands (>80 cm3). METHODS AND MATERIALS: Between January 2017 and December 2019, 33 patients with prostate glands >80 cm3 (mean 108.1 cm3; range, 81.1-186.6 cm3) were treated, 15 with glands >80 to 100 cm3 and 18 >100 cm3. Median follow-up was 10 months (range, 3-26). The median international prostate symptom score was 9 (range, 1-18). Hydrogel was placed under local anesthesia in all cases. Treatment modality included intensity modulated radiation therapy in 15 and proton therapy (PT) in 18 patients. Treatment targeted the prostate plus seminal vesicles in 21 patients and 12 also had elective nodal irradiation. Conventional fractionation (CF) to 78 Gy in 39 fractions was used in 16 and moderate hypofractionation (HF) to 70 Gy in 28 fractions in 17 patients. RESULTS: In the CF group, mean rectum (r) V75, 70, 60, 50 was 0.87%, 2.25%, 5.61%, and 10.5%, respectively. For glands >80 to 100 cm3 and >100 cm3, rV70 was 2.55% and 2%, respectively. In HF patients, mean rV65, 63, 60, and 50 was 1.67%, 2.3%, 3.4%, and 8.6%. For glands >80 to 100 cm3 and >100 cm3, rV63 was 2% and 2.56%, respectively. Overall, the mean midgland rectoprostatic hydrogel separation was 9.3 mm (range, 4.7-19.4 mm). All patients tolerated treatment well; no acute grade 2 or higher adverse gastrointestinal events were observed. CONCLUSIONS: Hydrogel placement is feasible in prostate glands larger than 80 cm3 with favorable dosimetric outcomes.

A Comprehensive Analysis of a Prospective Multidisciplinary Peer Review Process Before Radiation Therapy Simulation.

PURPOSE: Although peer review in radiation oncology (RO) has been recommended to improve quality of care, an analysis of modifications resulting from an RO multidisciplinary presimulation standardized review process has yet to be empirically demonstrated. METHODS AND MATERIALS: A standardized simulation directive was used for patients undergoing simulation for external beam radiation therapy at a single tertiary care institution. The simulation directives were presented, and all aspects were reviewed by representatives from key RO disciplines. Modifications to the original directives were prospectively captured in a quality improvement registry. Association between key variables and the incidence of modifications were performed using Fisher exact test and t test. RESULTS: A registry of 500 consecutive simulations for patients undergoing radiation therapy was reviewed. A median of 105 simulations occurred per month. All simulation directives were entered by a physician a median of 3 days before simulation (range, 1-76 days). The treatment intent was curative for 269 patients (53.8%), palliative for 203 patients (40.6%), and benign for 3 patients (0.6%). Twenty-five (5%) patients did not have a treatment intent selected. Based on RO multidisciplinary review, 105 directives (21%) were modified from the original intent, with 29 (5.8%) requiring more than 1 modification. A total of 149 modifications were made and categorized as changes to patient positioning and immobilization (n = 100, 20%), treatment site and care path (n = 34, 6.8%), simulation coordination activities (n = 6, 1.2%), and treatment technique and planning instructions (n = 9, 1.8%). A higher proportion of modifications occurred at the time of multidisciplinary review in patients receiving more complex treatments (intensity modulated radiation therapy/stereotactic radiosurgery/stereotactic body radiation therapy [IMRT/SRS/SBRT] vs 3-dimensional radiation therapy [3DCRT] radiation therapy, 25% vs 16%, P < .025). CONCLUSIONS: Given the complexity of radiation therapy simulation, standardization of directives with prospective RO multidisciplinary presimulation peer review is critical to optimizing department processes and reducing errors. Approximately 1 in 5 patients benefits from this peer review process, especially patients treated with IMRT/SRS/SBRT.

Proton Therapy for Breast Cancer: A Consensus Statement From the Particle Therapy Cooperative Group Breast Cancer Subcommittee.

Radiation therapy plays an important role in the multidisciplinary management of breast cancer. Recent years have seen improvements in breast cancer survival and a greater appreciation of potential long-term morbidity associated with the dose and volume of irradiated organs. Proton therapy reduces the dose to nontarget structures while optimizing target coverage. However, there remain additional financial costs associated with proton therapy, despite reductions over time, and studies have yet to demonstrate that protons improve upon the treatment outcomes achieved with photon radiation therapy. There remains considerable heterogeneity in proton patient selection and techniques, and the rapid technological advances in the field have the potential to affect evidence evaluation, given the long latency period for breast cancer radiation therapy recurrence and late effects. In this consensus statement, we assess the data available to the radiation oncology community of proton therapy for breast cancer, provide expert consensus recommendations on indications and technique, and highlight ongoing trials' cost-effectiveness analyses and key areas for future research.

Experience in a Brazilian Center with Cryoablation for Electric Isolation of the Pulmonary Veins in Paroxysmal and Persistent Atrial Fibrillation - Preliminary Results in Brazil. / Experiência de um Centro Brasileiro com Crioablação para Isolamento Elétrico das Veias Pulmonares na Fibrilação Atrial Paroxística e Persistente ­ Resultados Preliminares no Brasil.

BACKGROUND: Electrical isolation of the pulmonary veins is recognized as the cornerstone of non-pharmacological treatment of Atrial Fibrillation (AF), and therefore, has been recommended as the first step in AF ablation according to all guidelines. Even though the cryoballoon technology is widely used in North America and Europe, this experience is still incipient in many developing countries such as Brazil. OBJECTIVE: To evaluate initial results regarding success and safety of the new technology in patients with persistent and paroxysmal AF. METHODS: One hundred and eight consecutive patients with symptomatic AF refractory to pharmacological treatment were submitted to cryoablation for isolation of the pulmonary veins. Patients were separated into two groups according to AF classification: persistent (AF for over one week); or paroxysmal (shorter episodes). Recurrence and procedural safety data were analyzed respectively as primary and secondary outcomes. The level of significance was 5%. RESULTS: One hundred and eight patients, with mean age 58±13 years, 84 males (77.8%), underwent cryoablation. Sixty-five patients had paroxysmal AF (60.2%) and 43 had persistent AF (39.2%). The mean time of the procedure was 96.5±29.3 minutes and the mean fluoroscopy time was 29.6±11.1 minutes. Five (4.6%) complications were observed, none fatal. Considering a blanking period of 3 months, 21 recurrences (19.4%) were observed in a one-year follow-up period. The recurrence-free survival rates of AF in the paroxysmal and persistent groups were 89.2% and 67.4%, respectively. CONCLUSION: Cryoablation for electrical isolation of the pulmonary veins is a safe and effective method for the treatment of AF. Our results are consistent with other studies suggesting that this technology can be used as an initial technique even in cases of persistent AF.

FUNDAMENTO: O isolamento elétrico das veias pulmonares é reconhecidamente base fundamental para o tratamento não farmacológico da fibrilação atrial (FA) e, portanto, tem sido recomendado como passo inicial na ablação de FA em todas as diretrizes. A técnica com balão de crioenergia, embora amplamente utilizada na América do Norte e Europa, ainda se encontra em fase inicial em muitos países em desenvolvimento, como o Brasil. OBJETIVO: Avaliar o sucesso e a segurança da técnica de crioablação em nosso serviço, em pacientes com FA paroxística e persistente. MÉTODOS: Cento e oito pacientes consecutivos com FA sintomática e refratária ao tratamento farmacológico foram submetidos à crioablação para isolamento das veias pulmonares. Os pacientes foram separados em dois grupos, de acordo com a classificação convencional da FA paroxística (duração de até sete dias) e persistente (FA por mais de sete dias). Dados de recorrência e segurança do procedimento foram analisados respectivamente como desfechos primário e secundário. O nível de significância adotado foi de 5%. RESULTADOS: Cento e oito pacientes, com idade média de 58±13 anos, 84 do sexo masculino (77,8%), foram submetidos ao procedimento de crioablação de FA. Sessenta e cinco pacientes apresentavam FA paroxística (60,2%) e 43, FA persistente (39,2%). O tempo médio do procedimento foi de 96,5±29,3 minutos e o tempo médio de fluoroscopia foi de 29,6±11,1 minutos. Foram observadas cinco (4,6%) complicações, nenhuma fatal. Considerando a evolução após os 3 meses iniciais, foram observadas 21 recorrências (19,4%) em período de um ano de seguimento. As taxas de sobrevivência livre de recorrência nos grupos paroxístico e persistente foram de 89,2% e 67,4%, respectivamente. CONCLUSÃO: A crioablação para isolamento elétrico das veias pulmonares é um método seguro e eficaz para tratamento da FA. Nossos resultados estão consoantes com demais estudos, que sugerem que a tecnologia pode ser utilizada como abordagem inicial, mesmo nos casos de FA persistente. (Arq Bras Cardiol. 2020; [online].ahead print, PP.0-0).

Multi-Institutional Prospective Study of Reirradiation with Proton Beam Radiotherapy for Locoregionally Recurrent Non-Small Cell Lung Cancer.

OBJECTIVES: The management of recurrent NSCLC in the setting of prior radiation therapy is challenging. Proton radiotherapy (PRT) is ideally suited to minimize toxicity to previously irradiated organs. We report the safety/feasibility of PRT for NSCLC reirradiation in a prospective multi-institutional study. MATERIALS AND METHODS: Between October 2010 and December 2015, 57 patients with recurrent NSCLC in or near their prior radiation field were treated at three proton centers. Patients were classified by tumor volume, location, and clinical characteristics. Toxicities were scored using the National Cancer Institute Common Terminology Criteria for Adverse Events, version 4.0. Survival outcomes were estimated by using Kaplan-Meier analysis. RESULTS: Fifty-two patients (93%) completed the reirradiation course. Their median age was 65 years (41-86). Patients with high tumor volume (clinical target volume-to-internal target volume ratio ≥250 cm3) were closed to enrollment owing to infeasibility in August 2012. Concurrent systemic therapy was delivered to 67% of patients. Fourteen patients (25%) had evidence of local (n = 9) or regional (n = 5) recurrence. Distant metastases after reirradiation developed in six patients (11%). The 1-year rates of overall and progression-free survival were 59% and 58%, respectively. In total, grade 3 or higher acute and/or late toxicity developed in 24 patients (42%), acute toxicity developed in 22 (39%), and late toxicity developed in seven (12%). Six grade 5 toxicities were observed. Increased overlap with the central airway region, mean esophagus and heart doses, and concurrent chemotherapy were associated with significantly higher rates of grade 3 or higher toxicity. Decreased overall survival was seen with increased mean esophagus dose (p = 0.007). CONCLUSIONS: In this prospective study, PRT for recurrent NSCLC is feasible but can be associated with significant toxicity. Providers should remain cautious in reirradiating NSCLC, paying close consideration to tumor volume, location, and relevant dosimetric parameters. Further research is needed for optimal patient selection to improve overall outcomes.

Experiência de um Centro Brasileiro com Crioablação para Isolamento Elétrico das Veias Pulmonares na Fibrilação Atrial Paroxística e Persistente - Resultados Preliminares no Brasil / Experience in a Brazilian Center with Cryoablation for Electric Isolation of the Pulmonary Veins in Paroxysmal and Persistent Atrial Fibrillation - Preliminary Results in Brazil

Resumo Fundamento O isolamento elétrico das veias pulmonares é reconhecidamente base fundamental para o tratamento não farmacológico da fibrilação atrial (FA) e, portanto, tem sido recomendado como passo inicial na ablação de FA em todas as diretrizes. A técnica com balão de crioenergia, embora amplamente utilizada na América do Norte e Europa, ainda se encontra em fase inicial em muitos países em desenvolvimento, como o Brasil. Objetivo Avaliar o sucesso e a segurança da técnica de crioablação em nosso serviço, em pacientes com FA paroxística e persistente. Métodos Cento e oito pacientes consecutivos com FA sintomática e refratária ao tratamento farmacológico foram submetidos à crioablação para isolamento das veias pulmonares. Os pacientes foram separados em dois grupos, de acordo com a classificação convencional da FA paroxística (duração de até sete dias) e persistente (FA por mais de sete dias). Dados de recorrência e segurança do procedimento foram analisados respectivamente como desfechos primário e secundário. O nível de significância adotado foi de 5%. Resultados Cento e oito pacientes, com idade média de 58±13 anos, 84 do sexo masculino (77,8%), foram submetidos ao procedimento de crioablação de FA. Sessenta e cinco pacientes apresentavam FA paroxística (60,2%) e 43, FA persistente (39,2%). O tempo médio do procedimento foi de 96,5±29,3 minutos e o tempo médio de fluoroscopia foi de 29,6±11,1 minutos. Foram observadas cinco (4,6%) complicações, nenhuma fatal. Considerando a evolução após os 3 meses iniciais, foram observadas 21 recorrências (19,4%) em período de um ano de seguimento. As taxas de sobrevivência livre de recorrência nos grupos paroxístico e persistente foram de 89,2% e 67,4%, respectivamente. Conclusão A crioablação para isolamento elétrico das veias pulmonares é um método seguro e eficaz para tratamento da FA. Nossos resultados estão consoantes com demais estudos, que sugerem que a tecnologia pode ser utilizada como abordagem inicial, mesmo nos casos de FA persistente. (Arq Bras Cardiol. 2020; [online].ahead print, PP.0-0)

Abstract Background Electrical isolation of the pulmonary veins is recognized as the cornerstone of non-pharmacological treatment of Atrial Fibrillation (AF), and therefore, has been recommended as the first step in AF ablation according to all guidelines. Even though the cryoballoon technology is widely used in North America and Europe, this experience is still incipient in many developing countries such as Brazil. Objective To evaluate initial results regarding success and safety of the new technology in patients with persistent and paroxysmal AF. Methods One hundred and eight consecutive patients with symptomatic AF refractory to pharmacological treatment were submitted to cryoablation for isolation of the pulmonary veins. Patients were separated into two groups according to AF classification: persistent (AF for over one week); or paroxysmal (shorter episodes). Recurrence and procedural safety data were analyzed respectively as primary and secondary outcomes. The level of significance was 5%. Results One hundred and eight patients, with mean age 58±13 years, 84 males (77.8%), underwent cryoablation. Sixty-five patients had paroxysmal AF (60.2%) and 43 had persistent AF (39.2%). The mean time of the procedure was 96.5±29.3 minutes and the mean fluoroscopy time was 29.6±11.1 minutes. Five (4.6%) complications were observed, none fatal. Considering a blanking period of 3 months, 21 recurrences (19.4%) were observed in a one-year follow-up period. The recurrence-free survival rates of AF in the paroxysmal and persistent groups were 89.2% and 67.4%, respectively. Conclusion Cryoablation for electrical isolation of the pulmonary veins is a safe and effective method for the treatment of AF. Our results are consistent with other studies suggesting that this technology can be used as an initial technique even in cases of persistent AF.

Electrocardiogram during tachycardia in patients with anterograde conduction over a Mahaim fiber: old criteria revisited.

OBJECTIVES: The aim of this study was to prospectively evaluate the sensitivity, specificity, and positive and negative predictive values of previously described ECG criteria to identify preexcited tachycardia due to decrementally conducting accessory pathways (QRS axis between 0 and -75 degrees , QRS width < or = 0.15 seconds, an R wave in lead I, an rS pattern in lead V(1), RS > 1 QRS transition > V(4), and cycle length between 220 and 450 ms). BACKGROUND: Preexcited tachycardia associated with decrementally conducting right-sided accessory pathways usually shows a rather "narrow" QRS complex and can be difficult to differentiate from supraventricular tachycardia (SVT) with left bundle branch block (LBBB) aberrant conduction. METHODS: We analyzed three groups of patients: 32 patients with an atriofascicular pathway (group I); 8 patients with long (n = 3) or short (n = 5) decrementally conducting right-sided AV pathway (group II); and a control group that consisted of 35 patients with SVT and LBBB (group III). RESULTS: Presence of all six criteria had 87.5% sensitivity in group I and a 0% sensitivity in group II. There were four false negatives in group I. The negative predictive value was 82.5%, with six false positives in group III (five patients with an aberrant LBBB-shaped tachycardia with ventriculoatrial conduction over an accessory AV pathway). The criterion cycle length was not helpful. CONCLUSIONS: Criteria for identifying a tachycardia with anterograde conduction over a Mahaim fiber are helpful only in atriofascicular pathways, with a sensitivity of 87.5% and a negative predictive value of 82.5%. The major cause of false positives was a tachycardia with aberrant LBBB conduction and ventriculoatrial conduction over an accessory AV pathway.

Image-guided method for TLD-based in vivo rectal dose verification with endorectal balloon in proton therapy for prostate cancer.

PURPOSE: To present a practical image-guided method to position an endorectal balloon that improves in vivo thermoluminiscent dosimeter (TLD) measurements of rectal doses in proton therapy for prostate cancer. METHODS: TLDs were combined with endorectal balloons to measure dose at the anterior rectal wall during daily proton treatment delivery. Radiopaque metallic markers were employed as surrogates for balloon position reproducibility in rotation and translation. The markers were utilized to guide the balloon orientation during daily treatment employing orthogonal x-ray image-guided patient positioning. TLDs were placed at the 12 o'clock position on the anterior balloon surface at the midprostatic plane. Markers were placed at the 3 and 9 o'clock positions on the balloon to align it with respect to the planned orientation. The balloon rotation along its stem axis, referred to as roll, causes TLD displacement along the anterior-posterior direction. The magnitude of TLD displacement is revealed by the separation distance between markers at opposite sides of the balloon on sagittal x-ray images. RESULTS: A total of 81 in vivo TLD measurements were performed on six patients. Eighty-three percent of all measurements (65 TLD readings) were within +5% and -10% of the planning dose with a mean of -2.1% and a standard deviation of 3.5%. Examination of marker positions with in-room x-ray images of measured doses between -10% and -20% of the planned dose revealed a strong correlation between balloon roll and TLD displacement posteriorly from the planned position. The magnitude of the roll was confirmed by separations of 10-20 mm between the markers which could be corrected by manually adjusting the balloon position and verified by a repeat x-ray image prior to proton delivery. This approach could properly correct the balloon roll, resulting in TLD positioning within 2 mm along the anterior-posterior direction. CONCLUSIONS: Our results show that image-guided TLD-based in vivo dosimetry for rectal dose verification can be perfomed reliably and reproducibly for proton therapy in prostate cancer.

Contribution of the electrophysiological and anatomical analysis of the atypical atrioventricular nodal tachycardia circuit.

OBJECTIVES: To analyze retrograde conduction during junctional ectopic tachycardia (JET) episodes and investigate the existence of a relationship between the presence of a retrograde block and the risk of atrioventricular block (AVB) development during radiofrequency ablation procedures in patients with nodal atrioventricular tachycardia (NAVT). METHODS: 145 male and female patients aged 16-84 years, with NAVT who had undergone radiofrequency catheter ablation in the posteroseptal region of the right atrium were studied. Evaluation criteria were anatomical location and electrophysiological behavior of retrograde conduction during NAVT, in order to understand the nodal reentrant circuit (classifying the tachycardia as typical or atypical), and monitoring of retrograde conduction during JET episodes for risk-predicting AVB events. RESULTS: Of the 145 patients studied, 132 (91%) met electrophysiological and anatomical criteria of the typical form of NAVT, and 13 (9%) of atypical form. During the ablation, 5.3% with the typical form and 30.8% of the atypical form presented risk events for AVB. After the ablation, complications were a total AVB episode in one patient and a first-degree AVB episode in another in the typical group, and one first-degree AVB in the atypical group. All three episodes were preceded by risk events and resulted in permanent nodal injury. CONCLUSION: Patients with atypical NAVT presented higher percentages of risk events for atrioventricular block than did patients with the typical form (p=0.021).A careful observation of retrograde conduction during JET episodes is vital in order to avoid permanent damage in AV nodal conduction, such as TAVB, after the ablation procedure.

Ritmo com complexos QRS pouco alargados e sem atividade atrial: qual é o mecanismo ? / Narrow QRS complex rhythm without atrial activity: what is the mechanism?

Paciente admitido em fase aguda de infarto do miocárdio apresentou registro eletrocardiográfico não usual. Os aspectos pertinentes do registro para a elucidação diagnóstica são discutidos.

A patient admitted with acute myocardial infarction presented an unusual electrocardiographic record. Therelevant aspects of the record for confirming the diagnosis are discussed.

Effects of right bundle branch block on the antidromic circus movement tachycardia in patients with presumed atriofascicular pathways.

BACKGROUND: The typical and most common tachycardia in patients with atriofascicular pathways is a macro reentrant tachycardia, with anterograde conduction over the decrementally conducting bypass tract and retrograde conduction over the right bundle branch-His-AV node axis resulting in a short V-right bundle branch and short V-H interval. OBJECTIVES: To report on changes in rate and QRS configuration when right bundle branch block (RBBB) develops spontaneously during antidromic tachycardia using an atriofascicular fiber. METHODS: Three of 25 patients with an antidromic circus movement tachycardia using a right-sided atriofascicular pathway showed episodes of right bundle branch block (RBBB) during ventriculo-atrial conduction. Effect of retrograde RBBB on tachycardia rate and QRS configuration was studied using intracardiac and extracardiac recordings. RESULTS: All 3 patients showed prolongation of their V-A interval when retrograde RBBB occurred during tachycardia, resulting in a longer tachycardia cycle length. The VA time increase ranged from 85 to 100 msec, with a mean 346 +/- 5 msec. Two of the 3 patients also showed a change in QRS configuration due to a more leftward shift of the frontal plane QRS axis. CONCLUSION: Rate changes in antidromic tachycardia in patients with atriofascicular fibers can be based on a shift in VA conduction from one bundle branch to the other. This may be accompanied by changes in the frontal plane QRS axis because of a change in ventricular activation sequence.

Short atrioventricular Mahaim fibers: observations on their clinical, electrocardiographic, and electrophysiologic profile.

UNLABELLED: Short A-V manheim fiber. INTRODUCTION: A short atrioventricular decrementally conducting accessory pathway is an uncommon variant of preexcitation. Available data from small series suggest that their decremental properties might not be caused by A-V nodal-like tissue. METHODS: We compared clinical, electrocardiographic and electrophysiologic parameters in two groups of patients: 8 patients with a short A-V Mahaim pathway (Group A), and 33 patients with atriofascicular pathways (Group B). Radiofrequency catheter ablation was carried out guided by activation mapping at the annulus in Group A patients and targeting the "M" potential in Group B patients. RESULTS: After ablation of all associated rapidly conducting bypass tracts, 7 of the 8 Group A patients showed clear preexcitation. In only 1 of 8 patients the short A-V Mahaim fiber was actively engaged in a reentrant tachycardia circuit. During radiofrequency catheter ablation an automatic rhythm occurred in 4 of 8 patients. Intravenous adenosine caused conduction a block in the Mahaim fiber in 3 of the 5 patients tested. In group B, no patient showed clear preexcitation (P<00001) while 72% had a minimal preexcitation pattern. Twenty-nine of the 33 patients had a circus movement tachycardia with AV conduction over the atriofascicular fiber. During radiofrequency catheter ablation 30 of 33 patients showed accessory pathway automaticity. Adenosine caused transient block at the atriofascicular pathway in 11 (92%) of the 12 patients tested. CONCLUSIONS: While short decrementally conducting right-sided accessory pathways show a typical ECG pattern different from atriofascicular pathways, their electrophysiologic properties do not seem to be uniform. Those pathways can be successfully interrupted by catheter ablation.

Automaticity in Mahaim fibers.

INTRODUCTION: Automatic rhythms associated with Mahaim fibers usually occur during radiofrequency catheter ablation. The incidence and significance of spontaneous automaticity in Mahaim fibers are unknown. METHODS AND RESULTS: Spontaneous automatic rhythms were observed in 5 (12.5%) of 40 patients with Mahaim fibers referred for nonpharmacologic therapy because of recurrent episodes of symptomatic tachyarrhythmias, usually antidromic circus movement tachycardia (33/40 patients). Three were female and two were male. Their mean age was 15 +/- 7 years compared to 26 +/- 13 years of the patients without automaticity (P = 0.09). Three patients had both antidromic tachycardia and asymptomatic spontaneous automatic rhythms recorded during ambulatory ECG (1 patient) or electrophysiologic study (2 patients). In 2 patients, the automatic rhythm triggered antidromic tachycardia. Two other patients had nonsustained repetitive episodes of wide QRS tachycardia due to automaticity arising in the Mahaim fiber, without antidromic tachycardia. All automatic rhythms were abolished by successful catheter ablation of the Mahaim fibers. CONCLUSION: Spontaneous automaticity occurred in 12.5% of our Mahaim patients and may trigger antidromic tachycardia. Spontaneous automaticity, which is not seen in rapidly conducting accessory pathways, is another argument for the presence of an AV nodal-like structure in Mahaim fibers.