Radiation reduction in pediatric and adult congenital patients during cardiac catheterization

The burden of radiation exposure in congenital heart disease: the Italian cohort profile and bioresource collection in HARMONIC project

BACKGROUND

The European-funded Health Effects of Cardiac Fluoroscopy and Modern Radiotherapy in Pediatrics (HARMONIC) project aims to improve knowledge on the effects of medical exposure to ionizing radiation (IR) received during childhood. One of its objectives is to build a consolidated European cohort of pediatric patients who have undergone cardiac catheterization (Cath) procedures, with the goal of enhancing the assessment of long-term radiation-associated cancer risk. The purpose of our study is to provide a detailed description of the Italian cohort contributing to the HARMONIC project, including an analysis of cumulative IR exposure, reduction trend over the years and an overview of the prospective collection of biological samples for research in this vulnerable population.

METHODS

In a single-center retrospective cohort study, a total of 584 patients (323 males) with a median age of 6 (2-13) years, referred at the Pediatric Cardiology in Niguarda Hospital from January 2015 to October 2023, were included. Biological specimens from a subset of 60 patients were prospectively collected for biobanking at baseline, immediately post-procedure and after 12 months.

RESULTS

Two hundred fifty-nine (44%) patients were under 1 year old at their first procedure. The median KAP/weight was 0.09 Gy·cm2/kg (IQR: 0.03-0.20), and the median fluoroscopy time was 8.10 min (IQR: 4.00-16.25). KAP/weight ratio showed a positive correlation with the fluoroscopy time (Spearman's rho = 0.679, p < 0.001). Significant dose reduction was observed either after implementation of an upgraded technology system and a radiation training among staff. The Italian cohort includes 1858 different types of specimens for Harmonic biobank, including blood, plasma, serum, clot, cell pellet/lymphocytes, saliva.

CONCLUSIONS

In the Italian Harmonic cohort, radiation dose in cardiac catheterization varies by age and procedure type. An institution's radiological protection strategy has contributed to a reduction in radiation dose over time. Biological samples provide a valuable resource for future research, offering an opportunity to identify potential early biomarkers for health surveillance and personalized risk assessment.

[Hybrid operating theater]

A hybrid suite is an operating theater with imaging equipment equivalent to that used in an angiography suite with computed tomography (CT) and magnetic resonance imaging (MRI). They are often situated outside the operating room area and typically serve as multifunctional rooms designed to support a variety of catheter-based endovascular procedures and open surgery to be performed in the same location. The possibility to perform these in the same location facilitates the combination of both approaches to so-called hybrid procedures. Typical clinical applications of hybrid suites are cardiac, thoracic and vascular surgery, neurosurgery and neuroradiology, as well as orthopedics and traumatology. Transcatheter aortic valve implantation (TAVI) is significantly less invasive than a classical approach by open surgery. Patients older than 75 years with relevant comorbidities benefit most from the minimally invasive interventional approach. There has been a paradigm shift in the management of vascular diseases from open surgical repair to new percutaneous endovascular interventions with good early outcomes. Of particular interest in this context is the ability to block the part of the aorta proximal to the aneurysm with a catheter-based dilatation balloon. Progress in image fusion technology and intraoperative navigation has led to an increased acceptance of hybrid suites in orthopedics and traumatology. The complex care of high-risk patients most often outside the operating theater area is a challenge for the anesthesia team. This demands meticulous planning on behalf of the anesthesiologist to ensure an appropriate and safe strategy for anesthesia, intraoperative monitoring, vascular access and the need for additional equipment. A thorough understanding of the complexity of procedures is vital and a series of questions must be addressed: what is needed to safely administer anesthesia in this environment? What additional resources would be needed for an emergency situation? Is the patient being kept safe from radiation hazards? Moreover, logistics may become an issue as the hybrid suite is most often delocalized. In addition, many procedures realized in a hybrid suite require a multidisciplinary approach and therefore teamwork and professional communication are mandatory. Anesthesiologists need to have an integral role in the hybrid suite team, understanding and anticipating the risks for patients and leading the organization of workflow. The challenge in anesthesia is to ensure that when patients are taken to these complex environments the resources available enable high standards of care to be provided. With future developments in imaging technology combined with more powerful hardware and software, a far greater integration of all these imaging and navigation technologies will be seen in future operating rooms. Finally, patients are becoming more aware of medical developments via the world wide web and increasingly request what they consider to be state of the art treatment.

Reducing Radiation Exposure in Cardiac Catheterizations for Congenital Heart Disease

Ionizing radiation exposure is a necessary risk entailed during congenital cardiac catheterizations. The congenital catheterization lab at Yale New Haven Children's Hospital employed quality improvement strategies to minimize radiation exposure in this vulnerable population. In two phases, we implemented six interventions, which included adding and utilizing lower fluoroscopy and digital angiography (DA) doses, increasing staff and physician radiation awareness, focusing on tighter collimation, and changing the default fluoroscopy and DA doses to lower settings. Post-intervention data were collected prospectively for all procedures in the congenital catheterization lab and compared to pre-intervention radiation data collected retrospectively. Radiation exposure was measured in total air kerma (mGy), dose area product per body weight (DAP/kg) (µGy m²/kg), and fluoroscopy time (min). Data were collected for a total of 312 cases. In considering all procedures, the DAP/kg decreased by 67.6% and air kerma decreased by 63%. Fluoroscopy time did not change over the study period. Significant decreases in radiation exposure (DAP/kg) by procedure type were seen for atrial septal defect, patent ductus arteriosus, and transcatheter pulmonary valve procedures with a 45%, 42% and 83% decrease, respectively. Air kerma decreased significantly for ASD and PDA procedures with an 80% and 72% decrease, respectively. When compared to national benchmarks, the median DAP/kg and air kerma for these procedures are lower at our institution. The decreases continue to be sustained 2 years post-interventions. Systems-based interventions can be readily implemented in the congenital cardiac catheterization lab with dramatic and sustainable radiation dose reduction for patients.

Choice of tube extremity for emission of the lowest radiation dose in pediatric patients

AIMS

To compare the dosage of radiation the thyroid and gonad glands receive in pediatric patients undergoing chest X-rays, in distinct positions, towards the goal of developing of an X-ray tube positioning protocol.

METHODS

A randomized controlled clinical trial was carried out in the Pediatric Intensive Care Unit (PICU) at the Institute of Cardiology/University Foundation of Cardiology of Rio Grande do Sul, Brazil from June 2014 to September 2016. Patients were divided into two groups. One group was positioned with the thyroid gland facing the anode end of an X-ray tube, and in the other group the thyroid gland faced the cathode end. Radiographs were evaluated by five observers, following criteria recommended by the Commission of the European Communities (CEC).

RESULTS

Forty-eight pediatric patients, with a mean age of 2.0 ± 1.3 years, participated in this study. Based on the evaluation of 48 images, it was determined that the thyroid and gonad glands facing the cathode were exposed to 13.3 ± 3.1 μGy and 13.5 ± 4.1 μGy of radiation, respectively (p = 0.008). Additionally, the thyroid and gonad glands facing the anode were exposed to 11.7 ± 3.1 μGy and 12.7 ± 3.1 μGy of radiation, respectively (p = 0.007). The mean input dose in the center of the chest was 20.8 ± 9.6 μGy in both positions.

DISCUSSION

The proximity of the thyroid gland to the cathode end of the X-ray tube appears to be related to the dosage of ionizing radiation. Adverse effects associated with exposure to ionizing radiation could be minimized by positioning the thyroid gland to the anodic end of the X-ray tube.

CONCLUSION

Patients should be placed facing the anode end of the X-ray tube when taking thoracic X-rays, in order to reduce radiation exposure to the thyroid and gonad glands.ClinicalTrials.gov Identifier: NCT02925936.

Recommendations for the configuration of a cardiac catheterisation laboratory for the treatment of children with CHD

A modern catheter laboratory for the treatment of children with CHD should be in close proximity to the paediatric ICU, operating theatres, and imaging facilities. Space requirements and equipment for an up-to-date catheter laboratory are discussed. The document was endorsed by the council of the Association of European Paediatric and Congenital Cardiologists.

Comparison of skin dose measurement using nanoDot® dosimeter and machine readings of radiation dose during cardiac catheterization in children

Objectives

Direct measurement of skin dose of radiation for children using optically stimulated luminescence (OSL) technology using nanoDot^® (Landauer, Glenwood, IL, USA).

Background

Radiation dose is estimated as cumulative air kerma (AK) and dosearea product based on standards established for adult size patients. Body size of pediatric patients who undergo cardiac catheterization for congenital heart disease vary widely from newborn to adolescence. Direct, skindose measurement applying OSL technology may eliminate errors in the estimate.

Materials and Methods

The nanoDot^® (1 cm × 1 cm × flat plastic cassette) is applied to patient's skin using adhesive tape during cardiac catheterization and radiation skin doses were read within 24 hrs. nanoDot^® values were compared to the currently available cumulative AK values estimated and displayed on fluoroscopy monitor.

Results

A total of 12 children were studied, aged 4 months to 18 years (median 1.1 years) and weight range 5.3-86 kg (median 8.4 kg). nanoDot® readings ranged from 2.58 mGy to 424.8 mGy (median 84.1 mGy). Cumulative AK ranged from 16.2 mGy to 571.2 mGy (median 171.1 mGy). Linear correlation was noted between nanoDot® values and AK values (R² = 0.88, R = 0.94). nanoDot® readings were approximately 65% of the estimated cumulative AK estimated using the International Electrotechnical Commission standards.

Conclusions

Application of OSL technology using nanoDot® provides an alternative to directly measure fluoroscopic skin dose in children during cardiac catheterization. Our data show that the actual skin dose for children is approximately one-third lower than the AK estimated using international standards for adult size patients.

Removal of scatter radiation in paediatric cardiac catheterisation: a randomised controlled clinical trial

OBJECTIVE

This study sought to determine if DNA integrity was compromised by ionising radiation from paediatric cardiac catheterisations and if dose optimisation techniques allowed DNA integrity to be maintained.

MATERIALS AND METHODS

Children were imaged using either: (i) an anti-scatter grid (current departmental protocol), (ii) no anti-scatter grid or, (iii) no anti-scatter grid and a 15 cm air-gap between the child and the x-ray detector. Dose area product and image quality were assessed, lifetime attributable cancer risk estimates were calculated and DNA double-strand breakages quantified using the γH2AX assay.

RESULTS

Consent was obtained from 70 parents/guardians/children. Image quality was sufficient for each procedure performed. Removal of the anti-scatter grid resulted in dose reductions of 20% (no anti-scatter grid) and 30% (15 cm air-gap), DNA double-strand break reductions of 30% (no anti-scatter grid) and 20% (15 cm air-gap) and a reduction of radiation-induced cancer mortality risk of up to 45%.

CONCLUSION

Radiation doses received during paediatric cardiac catheterisation procedures resulted in a significant increase in DNA damage while maintaining acceptable image quality and diagnostic efficacy. It is feasible to remove the anti-scatter grid resulting in a reduction in DNA damage to the patient. The γH2AX assay may be used for assessment of dose optimisation strategies in children.

Changing Landscape of Congenital Heart Disease

Congenital heart disease is the most frequently occurring congenital disorder affecting ≈0.8% of live births. Thanks to great efforts and technical improvements, including the development of cardiopulmonary bypass in the 1950s, large-scale repair in these patients became possible, with subsequent dramatic reduction in morbidity and mortality. The ongoing search for progress and the growing understanding of the cardiovascular system and its pathophysiology refined all aspects of care for these patients. As a consequence, survival further increased over the past decades, and a new group of patients, those who survived congenital heart disease into adulthood, emerged. However, a large range of complications raised at the horizon as arrhythmias, endocarditis, pulmonary hypertension, and heart failure, and the need for additional treatment became clear. Technical solutions were sought in perfection and creation of new surgical techniques by developing catheter-based interventions, with elimination of open heart surgery and new electronic devices enabling, for example, multisite pacing and implantation of internal cardiac defibrillators to prevent sudden death. Over time, many pharmaceutical studies were conducted, changing clinical treatment slowly toward evidence-based care, although results were often limited by low numbers and clinical heterogeneity. More attention has been given to secondary issues like sports participation, pregnancy, work, and social-related difficulties. The relevance of these issues was already recognized in the 1970s when the need for specialized centers with multidisciplinary teams was proclaimed. Finally, research has become incorporated in care. Results of intervention studies and registries increased the knowledge on epidemiology of adults with congenital heart disease and their complications during life, and at the end, several guidelines became easily accessible, guiding physicians to deliver care appropriately. Over the past decades, the landscape of adult congenital heart disease has changed dramatically, which has to be continued in the future.

Reducing Fluoroscopic Radiation Exposure During Endomyocardial Biopsy in Pediatric Transplant Recipients

Endomyocardial biopsy (EMB) with fluoroscopy is used for rejection surveillance in pediatric heart transplantation. Lowering frame rate may reduce radiation, but decreases temporal resolution and image quality. We undertook a quality initiative reducing frame rate from 10 frames per second (FPS) to 5 FPS. To assess whether lowering frame rate can reduce radiation exposure without compromising safety, data on EMBs from 9/2009 to 4/2013 without angiography or intervention were reviewed. Effective dose was calculated from dose area product (DAP) and fluoroscopy time. Complications were reviewed. Independent t test compared pre- and post-data and a general linear model were used to control for confounders. Paired t test of most proximate data was used for pts with EMB before and after our change. Eighty-six patients had 543 EMB. After adjusting for weight, attending, and presence of a fellow, the lower FPS group had a 60.3% reduction in DAP (p < 0.0001) and 53.8% drop in effective dose (p < 0.0001). Fluoroscopy time did not differ. Twenty-eight pts had EMBs both before and after the FPS change. Pair-wise analysis of this group demonstrated a 33% reduction in DAP (p < 0.05) and 37% drop in effective dose (p < 0.01), without difference in fluoroscopy time. No patient had an increase in TR > 1 grade by ECHO. There were no deaths or perforations. Lowering the frame rate reduces radiation exposure by >50% without compromising safety. Efforts to further minimize radiation exposure of this vulnerable population should be considered.

Anaesthesia outside of the operating room: the paediatric cardiac catheterization laboratory

PURPOSE OF REVIEW

The focus of cardiac catheterization has changed from principally a diagnostic procedure to providing therapeutic options at various stages of childhood and adult congenital heart disease. The paediatric cardiac catheterization laboratory functions as a 'satellite' operating room. Combined ('hybrid') procedures with interventional cardiologists and cardiac surgeons present additional challenges for anaesthesia. The increased patient and procedure complexity represents higher risk for anaesthesia-related adverse events.

RECENT FINDINGS

This review concentrates on the recent efforts to determine these patient and procedure-related risks. Multicentre registries have been developed, generating information regarding adverse events and patient outcomes. Standardized adverse events ratios allow comparisons between institutions and providers. Models to identify high-risk groups have been developed.

SUMMARY

Advances in paediatric cardiac catheterization have created significant challenges for delivering anaesthesia in this environment. Anaesthetists need to have an integral role in the cardiac catheterization team, understanding and anticipating the risks for patients and leading the organization of workflow. Techniques used to improve systems in the operating room have been introduced to the cardiac catheterization laboratory to promote patient safety.

Radiation Reduction Capabilities of a Next-Generation Pediatric Imaging Platform

The aims of this study were to quantify patient radiation exposure for a single interventional procedure during transition from an adult catheterization laboratory to a next-generation imaging system with pediatric settings, and to compare this radiation data to published benchmarks. Radiation exposure occurs with any X-ray-directed pediatric catheterization. Technologies and imaging techniques that limit dose while preserving image quality benefit patient care. Patient radiation dose metrics, air kerma, and dose-area product (DAP) were retrospectively obtained for patients <20 kg who underwent patent ductus arteriosus (PDA) closure on a standard imaging system (Group 1, n = 11) and a next-generation pediatric imaging system (Group 2, n = 10) with air-gap technique. Group 2 radiation dose metrics were then compared to published benchmarks. Patient demographics, procedural technique, PDA dimensions, closure devices, and fluoroscopy time were similar for the two groups. Air kerma and DAP decreased by 65-70% in Group 2 (p values <0.001). The average number of angiograms approached statistical significance (p value = 0.06); therefore, analysis of covariance (ANCOVA) was conducted that confirmed significantly lower dose measures in Group 2. This degree of dose reduction was similar when Group 2 data (Kerma 28 mGy, DAP 199 µGy m(2)) was compared to published benchmarks for PDA closure (Kerma 76 mGy, DAP 500 µGy m(2)). This is the first clinical study documenting the radiation reduction capabilities of a next-generation pediatric imaging platform. The true benefit of this dose reduction will be seen in patients requiring complex and often recurrent catheterizations.