Quantifying and Minimizing Radiation Exposure During Pediatric Cardiac Catheterization

This study reports findings from evaluations of new technologies to measure radiation exposure during pediatric cardiac catheterization procedures. A strategy of pulsed fluoroscopy and low power settings resulted in significantly lower patient radiation exposure compared to conventional 60 frames/sec, high-power settings during fluoroscopy. During radiofrequency ablation procedures, thyroid and thoracic skin sites outside the direct fluoroscopic field received minimal radiation exposure. Intrathoracic radiation exposure was measured with the use of an esophageal dosimeter. In conclusion, strategies to reduce total radiation exposure should be employed, radiation dose should be measured, and assessment of radiation skin injury should be included in postcatheterization assessment.     

Radiation Exposure by Three-Dimensional Rotational Angiography (3DRA) During Trans-catheter Melody Pulmonary Valve Procedures (TMPV) in a Pediatric Cardiac Catheterization Laboratory

This retrospective study aims to evaluate radiation exposure by three-dimensional rotational angiography (3DRA) during trans-catheter Melody pulmonary valve (TMPV) procedures. 3DRA has been reported to have added value in the management of complex congenital heart disease aiding in the performance of interventional procedures albeit with concerns of higher radiation exposure. We test the hypothesis that 3DRA does not cause additional radiation exposure during TMPV procedures. We analyzed all 81 TMPV procedures performed at St. Louis Children’s Hospital, MO, USA, from January 1, 2011 to December 31, 2014. Dose-area product (DAP), DAP indexed to body weight (DAP/BW), fluoroscopy time (FT), and weight–fluoroscopy time product of each procedure were recorded. We reviewed each procedure’s images to determine whether additional interventions were performed (e.g., pulmonary artery angioplasty or treatment of conduit pseudo-aneurysm). 3DRA was used in 36 % of the procedures. 3DRA group had a higher number of additional procedures performed. The 3DRA group did not differ from the non-3DRA group in DAP, DAP/BW, and weight–fluoroscopy time product. 3DRA does not cause greater radiation exposure during TMPV procedures.     

Building a Pediatric Cardiac Catheterization Laboratory and Conference Room: Design Considerations and Filmless Imaging

Building or upgrading a dedicated pediatric cardiac catheterization laboratory is an expensive and elaborate undertaking complicated by long-standing biases based on adult laboratory requirements. Optimal design for the needs of pediatric cardiologists and their patients has never been published. This communication discusses these design issues in the context of pediatric needs and offers potential solutions. It also attempts to educate the reader on the basics of digital imaging and its advantages over cine film technology; and it explains how to achieve optimal filmless data acquisition and subsequent display for pediatric cardiac management.     

Radiation Exposure in Children During the Current Era of Pediatric Cardiac Intervention

Cardiac catheterizations are among the X-ray procedures with the highest patient radiation dose and therefore are of great concern in pediatric settings. This study aimed to evaluate factors that influence variability of X-ray exposure in children with congenital heart diseases during cardiac catheterization. The study included 107 children who underwent either diagnostic (n = 46) or interventional (n = 61) procedures. A custom-made sheet for patient and procedural characteristics was designed. Data were collected, and different correlations were applied to determine factors that influence variability of X-ray exposure. The flouroscopy time (FT) differed significantly between the diagnostic (8.9 ± 6.3 min) and intervention (12.8 ± 9.98 min) groups (P = 0.032). The mean dose–area product (DAP) differed significantly between the two groups (3.775 ± 2.5 Gy/cm² vs. 13.239 ± 15.4 Gy/cm²; P = 0.003). The highest DAP was during left anterior oblique (LAO) cranial 30° angulation (2.8 Gy/cm²/4 s cine). The mean cumulative dose (CD) was 0.053 Gy in diagnostic cases and 0.48 Gy in intervention cases. The effective dose was 5.97 ± 7.05 mSv for theraputic procedures compared with 3.42 ± 3.64 mSv for diagnostic procedures. The FT correlated significantly with both the DAP (r = 0.718; P < 0.001) and the CD (r = 0.701; P < 0.001). Other correlations were reported. An increasing number of therapeutic catheterization procedures are being performed for children. The justification for these procedures is evident because they avoid complicated surgery. However, the complexity of these procedures results in higher radiation exposures.     

Effective Radiation Dose in Computed Tomographic Angiography of the Chest and Diagnostic Cardiac Catheterization in Pediatric Patients

Computed tomographic angiography (CTA) and cardiac catheterization are useful adjuncts to echocardiography for delineating cardiovascular anatomy in pediatric patients. These studies require ionizing radiation, and it is paramount to understand the amount of radiation pediatric patients receive when these tests are performed. Modern dosimetry methods facilitate the conversion of radiation doses of varying units into an effective radiation dose. To compare the effective radiation dose between nongated CTA of the chest and diagnostic cardiac catheterization in pediatric patients. This is a retrospective cohort study of patients of patients who underwent either nongated CTA of the chest or diagnostic cardiac catheterization between July 2009 and April 2010. Fifty patients were included in each group as consecutive samples at a single tertiary care center. An effective radiation dose (mSv) was formulated using conversion factors for each group. The median effective dose (ED) for the CTA group was 0.74 mSv compared with 10.8 mSv for the catheterization group (p < 0.0001). The median ED for children <1 year of age in the CTA group was 0.76 mSv compared with 13.4 mSv for the catheterization group (p < 0.0001). Nongated CTA of the chest exposes children to 15 times less radiation than diagnostic cardiac catheterization. Unless hemodynamic data are necessary, CTA of the chest should be considered in lieu of diagnostic cardiac catheterization in patients with known or presumed cardiac disease who need additional imaging beyond echocardiography     

Radiation Safety Protocol Using Real-Time Dose Reporting Reduces Patient Exposure in Pediatric Electrophysiology Procedures

Radiation exposure during pediatric catheterization is significant. We sought to describe radiation exposure and the effectiveness of radiation safety protocols in reducing exposure during catheter ablations with electrophysiology studies in children and patients with congenital heart disease. We additionally sought to identify at-risk patients. We retrospectively reviewed all interventional electrophysiology procedures performed from April 2009 to September 2011 (6 months preceding intervention, 12 months following implementation of initial radiation safety protocol, and 8 months following implementation of modified protocol). The protocols consisted of low pulse rate fluoroscopy settings, operator notification of skin entrance dose every 1,000 mGy, adjusting cameras by >5 at every 1,000 mGy, and appropriate collimation. The cohort consisted of 291 patients (70 pre-intervention, 137 after initial protocol implementation, 84 after modified protocol implementation) at a median age of 14.9 years with congenital heart disease present in 11 %. Diagnoses included atrioventricular nodal reentrant tachycardia (25 %), atrioventricular reentrant tachycardia (61 %), atrial tachycardias (12 %), and ventricular tachycardia (2 %). There were no differences between groups based on patient, arrhythmia, and procedural characteristics. Following implementation of the protocols, there were significant reductions in all measures of radiation exposure: fluoroscopy time (17.8 %), dose area product (80.2 %), skin entry dose (81.0 %), and effective dose (76.9 %), p = 0.0001. Independent predictors of increased radiation exposure included larger patient weight, longer fluoroscopy time, and lack of radiation safety protocol. Implementation of a radiation safety protocol for pediatric and congenital catheter ablations can drastically reduce radiation exposure to patients without affecting procedural success.     

Ultrasound- Versus Landmark-Guided Femoral Catheterization in the Pediatric Catheterization Laboratory: A Randomized-Controlled Trial

Ultrasound (US) is the standard of care for vascular access in many clinical scenarios. Limited data exist regarding the benefits of US- versus landmark (LM)-guided femoral vascular access in the pediatric catheterization laboratory. This study aimed to compare US- and LM-guided vascular access in the pediatric catheterization laboratory. A single operator randomized 95 patients (201 vessels) to undergo either LM- or US-guided vascular access. The primary end point was the access success rate. Number of attempts, inadvertent access, time to sheath placement, and complications also were compared between the two groups. No difference was seen in the overall access success rate: 98 % with US versus 93 % with LM (p = 0.17). The success rate for the targeted vessel was higher with US (89 %) than with LM (67 %) (p = 0.012). US facilitated fewer attempts (1.1 ± 0.4 vs 1.4 ± 0.9; p = 0.048) and improved the first-attempt success rate (87 vs 77 %; p = 0.049). The time to access did not differ significantly between the two groups (US 2:55 ± 4:03 vs LM 3:37 ± 2:54; p = 0.28). No differences in complication rates were noted. The benefits of US were accentuated in the subgroup weighing less than 10 kg. In this study, US access in the pediatric catheterization laboratory did not improve overall success. However, US improved accuracy and reduced the number attempts necessary for access without prolonging the access time of the procedure. Small children realized the greatest benefit of US-guided access.     

Ultrasound-Guided Versus Landmark-Guided Femoral Vein Access in Pediatric Cardiac Catheterization

Background This study aimed to evaluate whether an ultrasound-guided technique can improve upon a landmark-guided technique in achieving femoral vein access in pediatric cardiac catheterization. Methods This study examined 87 consecutive subjects with a median age of 2 years (range, 1 month to 19 years) who had congenital or other heart disease. Femoral vein puncture was attempted using either an ultrasound-guided technique (US group, n = 43) or a landmark-guided technique (LM group, n = 44). The patients were assigned alternately to either an ultrasound- or landmark-guided group. Overall success and traumatic complication rates were compared between the two groups, as well as the influence of patient size and age. Results The overall rate of success in achieving femoral vein access did not differ between the two groups. Among the successful cases in the two groups, there were no significant differences in patient size or age. Inadvertent femoral artery puncture occurred with 3 (7%) of 43 patients in the US group and with 14 (31.8%) of 44 patients in the LM group, for a significantly higher complication rate in the LM group (p < 0.01). Conclusions Ultrasound-guided access to the femoral vein minimizes the complication of inadvertent arterial puncture as compared with the landmark-guided approach.     

Successful Femoral Vessel Puncture Facilitated by Using a J-Tipped Hydrophilic Guidewire in Pediatric Cardiac Catheterization

Vascular access is an important part of cardiac catheterization, but it is extremely difficult in some cases. We present two cases in which a J-tipped hydrophilic guidewire inserted from the contralateral vessel facilitated successful vascular access after initial access failure by conventional method using anatomical landmark.     

Patient Safety and Human Factors in Pediatric Cardiac Surgery

The patient safety movement and human factors studies are becoming an increasingly important part of everyday clinical practice. Pediatric cardiac surgery is a high-risk field that is very much dependent on safe practices and continuous research into improvement of outcomes. This article reviews the main research frameworks, methods used, and current findings in the area of patient safety and human factors within pediatric cardiac surgery.     

Cumulative Radiation Exposure in Pediatric Patients with Congenital Heart Disease

Certain pediatric patients undergoing surgery for the most severe forms of congenital heart disease are exposed to high doses of ionizing radiation. The amount of cumulative radiation exposure from all modalities has not yet been evaluated. The purpose of our study was to evaluate the cumulative radiation exposure in a contemporary cohort of patients with congenital heart disease undergoing single-ventricle palliation. This is a single-center, retrospective study of pediatric patients undergoing Fontan completion between May 2005 and May 2010. Radiation exposure from all procedures including cardiac catheterizations, computed tomography (CT) scans, plain film radiography, and nuclear medicine scans was evaluated. Radiation dose was calculated as the dose area product (μGy m²) and was measured in all cardiac catheterizations, CT scans, and other imaging modalities. Seventy patients who underwent Fontan completion at a mean age of 3.6 ± 1.5 years (range 1.4–8 years) were included in the study. Mean number of chest X-rays was 32 ± 8 (range 10–285) with a mean cumulative total exposure of 1,320 μGy m² (range 480–12,960) per patient. Mean number of cardiac catheterizations was 2.45 ± 1.3 (range 1–8), and mean fluoroscopy and cine angiography exposures per case were 1,103 ± 245 and 1,412 ± 273 μGy m² giving a mean cumulative exposure of 9,054 μGy m² (range 2,515–201,200) per patient for all catheterizations. Mean number of CT scans performed was 0.44 ± 0.4 (0–11), and the mean exposure was 352 μGy m², giving a mean cumulative total of 154 μGy m² (range 0–3,872) per person. A total of five lung perfusion scans were carried out. Radiation exposure in patients with congenital heart disease undergoing single-ventricle palliation is quite variable. Most of the exposure to ionizing radiation occurs during cardiac catheterization. Strategies to utilize other imaging modalities such as MRI would decrease exposure in this particular group of patients who may be particularly vulnerable to its side effects.     

Use of Low-Dose Ketamine and/or Midazolam for Pediatric Cardiac Catheterization

Ketamine and midazolam are commonly used in children undergoing cardiac catheterization. However, there is controversy regarding the safety of administering these agents in the absence of an anesthesiologist. We retrospectively reviewed pediatric cardiac catheterization procedures at our institution between 1996 and 1997. A total of 154 patients (0.3-192 months) underwent a total of 205 procedures. They received ketamine (n = 79, 1.05 +/- 0.88 mg/kg/hr), midazolam (n = 35, 0.14 +/- 0.09 mg/kg/hr), or both (n = 91; ketamine, 1.13 +/- 0.84 mg/kg/hr; midazolam, 1.57 +/- 1.03 mg/kg//hr). In 18.5% of patients there were complex cardiac lesions. Mean procedure time was 79 +/- 36.2 minutes. Pre- and postprocedure systolic and diastolic mean blood procedure 72 +/- 14 and 68 +/- 12 mmHg, respectively. Pre- and postprocedure O2 saturation was 93.19 +/- 8.72 and 93.63 +/- 8.3, respectively. One patient required intubation, and 15% required oxygen therapy. The mortality rate was zero. The anesthesiologist's assistance was requested by the cardiologist in 21 procedures (group A) and not requested in 184 procedures (group B). The two groups were not different in relation to the drug used (p = 0.283) or the complexity of the cardiac lesions (p = 0.051). However, there was significant difference between the two regarding the need for supporting drugs (3/21 vs 3/184, p = 0.02) or oxygen treatment (7/21 vs 26/184, p = 0.014). No patients in group B required intubation, whereas 14% and 1.6% required oxygen therapy and supporting drugs, respectively. We conclude that low-dose ketamine and midazolam can be administered safely to most pediatric patients by the cardiologist, who can safely predict the need for an anesthesiologist.     

Radiation Exposure and the Risk of Pediatric Thyroid Cancer

It has been more than three years since the unprecedentedly massive earthquake and tsunami struck eastern Japan on March 11, 2011, and the large accident occurred at the Fukushima Daiichi Nuclear Power Plant. To investigate the influence of radiation exposure, thyroid ultrasonography has been provided preliminarily for 360,000 children who lived in Fukushima Prefecture at the time of the accident. As of September 2013, 59 children had been diagnosed with thyroid cancer by fine-needle aspiration cytology, and 34 children had been treated surgically and ultimately diagnosed with papillary thyroid cancer. Here, I would like to describe the characteristics of pediatric thyroid cancer and typical thyroid images obtained by ultrasonography.     

Simplified Pulmonary Vasodilatory Testing in the Cardiac Catheterization Laboratory with Nasal Cannula Nitric Oxide

In patients with pulmonary hypertension, pulmonary vasodilator testing with inhaled nitric oxide (NO) during cardiac catheterization provides valuable data for defining future care plans. Previously, the use of delivery systems for spontaneously breathing individuals required a tight-fitting seal by face mask and an approved delivery and dilution device. We hypothesized that a simplified delivery system using nasal cannula could be utilized to effectively deliver NO during cardiac catheterization. We developed a simple delivery system to deliver through a nasal cannula a concentration of NO at 50 ppm at the nares along with supplemental oxygen (O₂) via face tent. We prospectively employed this system for 10-minute intervals on 11 patients (age range, 7 months to 41 years) with pulmonary hypertension undergoing scheduled cardiac catheterization. Mean pulmonary artery pressure (PA_p) decreased from 62 mmHg (range, 38–99) at room air testing to 45 mmHg (range, 36–91) with the addition of NO plus O₂ (p = 0.014). Pulmonary vascular resistance (PVR) decreased from 11.6 U · m² (range, 4.5–43.4) to 6.3 U · m² (range, 2.0–34.2) (p = 0.001). A response of 20% or more reduction in PVR was seen in all 11 patients. The initial ratio of pulmonary to systemic vascular resistance (R_p:R_s) was 0.49 (range, 0.25–3.5) and decreased to 0.35 (range 0.1–2.6) (p = 0.002). No adverse side effects were noted. We found this NO delivery system to be a simple and effective method of pulmonary vasodilatory testing that may have wide applicability in the cardiac catheterization laboratory.     

Staff Radiation Doses in Interventional Cardiology: Correlation With Patient Exposure

In pediatric interventional cardiology, cardiologists need to stay closer to the patient than during adult catheterization, and the use of biplane systems increases the scatter radiation. Occupational radiation risk is rather high, and estimation of lens doses becomes necessary. Deriving factors for assessing these doses from the patient doses displayed in catheterization laboratories can help in preserving staff radiation safety. A biplane X-ray system and polymethylmethacrylate plates of 4 to 20 cm to simulate pediatric patients have been used. Patient entrance dose rates, dose-area product, and doses to the eyes of the cardiologists for the typical operation modes have been measured. Correlations between patient and staff doses have been obtained. Scatter dose rates increase by a factor of 92 from low fluoroscopy to cine acquisition when phantom thickness increases from 4 to 20 cm. Scatter doses increase linearly with dose-area product for all the thicknesses. Administration of 1 Gy·cm² to the patient involves 7 μSv to the eyes of the cardiologist (without extra protection). In conclusion, the experimental correlation factors found between phantom and scatter doses allow a fairly good estimation of staff doses from the dosimetric patient data.