Factors Contributing to Acute Kidney Injury and the Impact on Mortality in Patients Undergoing Transcatheter Aortic Valve Replacement.

BACKGROUND: Transcatheter aortic valve replacement (TAVR) patients are at a high risk of acute kidney injury (AKI). This study aimed to investigate AKI and the relationship with iodinated contrast media (ICM), whether there are significant pre- or peri- procedural variables predicting AKI, and whether AKI impacts on hospital length of stay and mortality. METHODS: Serum creatinine (SC) levels pre- and post- (peak) TAVR were recorded in 209 consecutive TAVR patients. AKI was defined by the Valve Academic Research Consortium 2 (VARC2) criteria. Baseline characteristics, procedural variables, hospital length of stay (LOS) and mortality at 72hours, 30 days and one year were analysed. RESULTS: Eighty-two of 209 (39%) patients suffered AKI. Mean ICM volume was 228cc, with no difference between patients with AKI and those with no AKI (227cc (213-240(95%CI)) vs 231cc (212-250) p=0.700)). Univariate and multivariate analysis demonstrated that chronic kidney disease, respiratory failure, previous stroke, the need for blood transfusion and valve repositioning were all predictors of AKI. Acute kidney injury increased LOS (5.6 days (3.8 - 7.5) vs 3.2 days (2.6 - 3.9) no AKI (P=0.004)) but was not linked to increased mortality. Mortality rates did increase with AKI severity. CONCLUSION: Acute kidney injury is a common complication of TAVR. The severity of AKI is important in determining mortality. Acute kidney injury appears to be independent of ICM use but pre-existing renal impairment and respiratory failure were predictors for AKI. Transcatheter aortic valve replacement device repositioning or retrieval was identified as a new risk factor impacting on AKI.

Investigation of scatter radiation intensities in the cardiac catheter laboratory: novel versus traditional shielding solutions.

A manufacturer has released a novel shielding solution (NSS): Rampart M1128 and claimed that the personal protective equipment (PPE) can be removed. This study investigates the scatter intensities with the NSS or the traditional shielding solutions (TSS) including the ceiling-suspended screen and the tableside lead drape. Isodose maps were generated by two series of measurements with an anthropomorphic phantom using NSS and TSS. Three survey meters were positioned at different heights to measure the scatter intensities at the eye, chest, and pelvic levels. Additional measurements were made at the primary and secondary operators? locations to evaluate the scatter intensities with different clinical projections. For the main operator positions, the isodose maps showed that NSS could result in a scatter dose that reduced by 80% to 95% compared to the same positions with TSS at the eye and chest levels. The corresponding result at the pelvic level was a reduction of 50%. These reductions should be compared to the additional protection by PPE: up to 80% reduction from lead eyeglasses and up to 95% from protective garments. Considering both operators at clinically relevant LAO projections, NSS resulted in scatter dose that was 80% to 96%, 76% to 96% and 25% to 60% lower than those of the TSS at eye, chest and pelvis levels. The protection of NSS is comparable with that of TSS alongside PPE at the eye but not at the chest and the pelvic levels under the setup of coronary angiography.

Trial of a Novel Radiation Shielding Device to Protect Staff in the Cardiac Catheter Laboratory.

Continuous exposure to low-level scattered radiation to staff performing cardiac angiography and intervention is of concern. A novel shielding solution (NSS) (Rampart IC M1128) has the potential to provide greater shielding for staff present at the table-side. This study aimed to investigate the effectiveness of the NSS compared with a traditional shielding solution (TSS) in a randomized controlled trial that enrolled 100 patients who underwent cardiac angiography and/or intervention which were randomized to the NSS or TSS. Baseline patient characteristics and radiation dose data were collected. Staff who were scrubbed at the table-side wore 5 real-time dosimeters on the head, collar, waist, ankle, and under the apron. The median primary operator radiation dose was significantly lower (p <0.001) for all dosimeter locations with the NSS when compared with the TSS, being reduced by 86%, 80.0%, 100%, and 50.0% for the head, collar, waist, and leg respectively. Median under-apron dose was 0.0 µSv for both NSS and TSS. Median second operator dose was reduced by 100%, 100%, and 100% for the head, collar, and waist respectively (p <0.001). Median NSS and TSS dose at the ankle and under apron was 0.0 µSv. Median scrub nurse dose was reduced by 50% and 100% for the head and collar respectively (p <0.001). Median NSS and TSS dose at the waist, ankle, and under apron was 0.0 µSv. In conclusion, the NSS tested in this study demonstrates a significant decrease in radiation dose to operators and scrub nurses when compared with traditional radiation protection measures.

Primary operator radiation dose in the cardiac catheter laboratory.

OBJECTIVES: Radiation from cardiac angiography procedures is harmful to patients and the staff performing them. This study sought to investigate operator radiation dose for a range of procedures and different operators in order to investigate trends and optimise dose. METHODS: Real-time dosemeters (RTDs) were worn by operators for angiography procedures for 3 years. Dose-area product (DAP) and RTD were collected. RTD was normalised to DAP (RTD/DAP) to compare radiation dose and radiation protection measures. Comparisons were made across procedure categories and individual operators. RESULTS: In 7626 procedures, median and 75th percentile levels were established for operator dose for 8 procedure categories. There was a significant difference in all operator dose measures and DAP across procedure categories (p<0.001). DAP, RTD, and RTD/DAP were significantly different across 22 individual operators (p<0.001). CONCLUSION: DAP was significantly different across procedure categories and a higher RTD was seen with higher DAP. RTD/DAP can demonstrate radiation protection effectiveness and identified differences between procedures and individual operators with this measure. Procedures and individuals were identified where further optimisation of radiation protection measures may be beneficial. A reference level for operator dose can be created and audited against on a regular basis. ADVANCES IN KNOWLEDGE: This study demonstrates that operator dose can be easily and routinely measured on a case by case basis to investigate dose trends for different procedures. Normalising the operator dose to DAP demonstrates radiation protection effectiveness for the individual operator which can then be optimised as part of an ongoing audit program.

Factors contributing to radiation dose for patients and operators during diagnostic cardiac angiography.

INTRODUCTION: Diagnostic coronary angiography (CA) uses ionising radiation with relatively high doses, which impact on both patients and staff. This study sought to identify which patient and procedural factors impact patient and operator dose the most during CA. METHODS: Patient and procedure related variables impacting on Kerma area product (PKA ) and operator dose (OD) were collected for 16 months. Procedures were separated into 10 different procedure categories. PKA was used for patient dose and OD was measured with an instantly downloadable dosimeter (IDD) - downloaded at the end of each procedure. High and low radiation dose was defined by binary variables based on the 75th percentile of the continuous measures. Univariate and multivariate regression were used to identify predictors. RESULTS: Of 3860 patients included, the IDD was worn for 2591 (61.7%). Obesity (BMI > 30 compared to BMI < 25) was the strongest predictor for both a PKA (odds ratio (OR) = 19.1 (95% CI 13.5-26.9) P < 0.001) and OD (OR = 3.3 (2.4-4.4) P < 0.001) above the 75th percentile. Male gender, biplane imaging, the X-ray unit used, operator experience and procedure type also predicted a high PKA . Radial access, male gender, biplane imaging and procedure type also predicted a high OD. CONCLUSION: Radiation dose during CA is multifactorial and is dependent on patient and procedure related variables. Many factors impact on both PKA and OD but obesity is the strongest predictor for both patients and operators to receive a high radiation dose.

Radiation Exposure of Operators Performing Transesophageal Echocardiography During Percutaneous Structural Cardiac Interventions.

BACKGROUND: Transesophageal echocardiography operators (TEEOP) provide critical imaging support for percutaneous structural cardiac intervention procedures. They stand close to the patient and the associated scattered radiation. OBJECTIVES: This study sought to investigate TEEOP radiation dose during percutaneous structural cardiac intervention. METHODS: Key personnel (TEEOP, anesthetist, primary operator [OP1], and secondary operator) wore instantly downloadable personal dosimeters during procedures requiring TEE support. TEEOP effective dose (E) and E per unit Kerma area product (E/KAP) were calculated. E/KAP was compared with C-arm projections. Additional shielding for TEEOP was implemented, and doses were measured for a further 50 procedures. Multivariate linear regression was performed to investigate independent predictors of radiation dose reduction. RESULTS: In the initial 98 procedures, median TEEOP E was 2.62 µSv (interquartile range [IQR]: 0.95 to 4.76 µSv), similar to OP1 E: 1.91 µSv (IQR: 0.48 to 3.81 µSv) (p = 0.101), but significantly higher than secondary operator E: 0.48 µSv (IQR: 0.00 to 1.91 µSv) (p < 0.001) and anesthetist E: 0.48 µSv (IQR: 0.00 to 1.43 µSv) (p < 0.001). Procedures using predominantly right anterior oblique (RAO) and steep RAO projections were associated with high TEEOP E/KAP (p = 0.041). In a further 50 procedures, with additional TEEOP shielding, TEEOP E was reduced by 82% (2.62 µSv [IQR: 0.95 to 4.76] to 0.48 µSv [IQR: 0.00 to 1.43 µSv] [p < 0.001]). Multivariate regression demonstrated shielding, procedure type, and KAP as independent predictors of TEEOP dose. CONCLUSION: TEE operators are exposed to a radiation dose that is at least as high as that of OP1 during percutaneous cardiac intervention. Doses were higher with procedures using predominantly RAO projections. Radiation doses can be significantly reduced with the use of an additional ceiling-suspended lead shield.

The effect of X-ray beam distortion on the Edwards Sapien XT(™) trans-catheter aortic valve replacement prosthesis.

INTRODUCTION: Profiling the Aortic root perpendicular to the fluoroscopic image plane will achieve a more successful implant position for trans-catheter aortic valve replacement (TAVR). This study aimed to investigate whether the divergent nature of the X-ray beam from the C-arm altered the appearance of the TAVR device. METHODS: Under bench-top testing, a 23, 26 and 29 mm Edwards Sapien XT valve was positioned coaxially at the bottom of a fluoroscopic image utilising 22 and 32 cm fields of view (FOV). The table was then moved so that the valve was positioned at the top of the image. The valve's appearance was scored using a previously published three tier classification tool (excellent, satisfactory and poor) and quantified with measurements. The number of degrees of C-arm rotation that were required to bring the valve back to a coaxial appearance was recorded. RESULTS: When using the 32 cm FOV, the valve's appearance changes from excellent to satisfactory. When a 22 cm FOV was used, the change is less marked. More C-arm rotation is required to bring the appearance back to coaxial with the 32 cm FOV. CONCLUSION: Not maintaining the valve in the centre of the image can distort the valves appearance. This has the potential to affect the final implantation depth.

Radiation dose in coronary angiography and intervention: initial results from the establishment of a multi-centre diagnostic reference level in Queensland public hospitals.

INTRODUCTION: Radiation dose to patients undergoing invasive coronary angiography (ICA) is relatively high. Guidelines suggest that a local benchmark or diagnostic reference level (DRL) be established for these procedures. This study sought to create a DRL for ICA procedures in Queensland public hospitals. METHODS: Data were collected for all Cardiac Catheter Laboratories in Queensland public hospitals. Data were collected for diagnostic coronary angiography (CA) and single-vessel percutaneous intervention (PCI) procedures. Dose area product (P KA), skin surface entrance dose (K AR), fluoroscopy time (FT), and patient height and weight were collected for 3 months. The DRL was set from the 75th percentile of the P KA. RESULTS: 2590 patients were included in the CA group where the median FT was 3.5 min (inter-quartile range = 2.3-6.1). Median K AR = 581 mGy (374-876). Median P KA = 3908 uGym(2) (2489-5865) DRL = 5865 uGym(2). 947 patients were included in the PCI group where median FT was 11.2 min (7.7-17.4). Median K AR = 1501 mGy (928-2224). Median P KA = 8736 uGym(2) (5449-12,900) DRL = 12,900 uGym(2). CONCLUSION: This study established a benchmark for radiation dose for diagnostic and interventional coronary angiography in Queensland public facilities.

Novel utilization of 3D technology and the hybrid operating theatre: Peri-operative assessment of posterior sterno-clavicular dislocation using cone beam CT.

A patient with a medial and posterior dislocation of the right sterno-clavicular (SC) joint and displacement of the trachea and brachiocephalic artery by the medial head of the clavicle underwent general anaesthetic in the operating theatre for an open reduction procedure. The surgeon initially attempted a closed reduction, but this required imaging to check SC alignment. The patient was transferred to an adjacent hybrid operating theatre for imaging. Cone beam computed tomography (CBCT) was performed, which successfully demonstrated a significant reduction in the dislocation of the SC joint. The trachea and brachiocephalic artery were no longer compressed or displaced. This case study demonstrates an alternative to the patient being transferred to the medical imaging department for multi-slice CT. It also describes a novel use of the hybrid operating theatre and its CBCT capabilities.

Using DynaCT for the assessment of ilio-femoral arterial calibre, calcification and tortuosity index in patients selected for trans-catheter aortic valve replacement.

Adequate vascular access for femoral trans-catheter aortic valve replacement is fundamental to the success of the procedure. Assessment of vascular calibre, tortuosity and calcification is performed by angiography and multi-slice computed tomography (MSCT). Can DynaCT provide the same information as MSCT? 15 Patients underwent MSCT, angiography and DynaCT. Vessel diameter measurements were taken in three positions of the left and right ilio-femoral arteries. Tortuosity was assessed using an index of the direct distance and the distance taken by the artery between two points. Calcification was assessed in MSCT and DynaCT using a simple scoring system. Concordance correlation coefficient of arterial calibre between angiography and MSCT was 0.96 (95 % CI 0.94-0.97). DynaCT and angiography was 0.94 (95 % CI 0.91-0.96) and Dyna CT and MSCT, 0.95 (95 % CI 0.92-0.97). Bland-Altman tests demonstrate a mean difference between the angiogram and the MSCT of 0.06 mm (+0.97, -1.42), angiogram and DynaCT, 0.13 mm, (+1.00, -0.87), DynaCT and MSCT, 0.2 mm, (+1.15, -0.76). Tortuosity comparisons gave a median tortuosity index for MSCT 1.29 and DynaCT 1.23 (p = 0.472). Calcification comparisons of MSCT and DynaCT using correlation coefficients demonstrate a correlation of 0.245 (p = 0.378). Effective radiation doses were: DynaCT; 3.63 ± 0.65 mSv and angiography; 0.57 ± 0.72 mSv, MSCT; 7.15 ± 2.58 mSv. DynaCT is equal to MSCT and angiography in assessing femoral artery calibre. Like MSCT, it can assess tortuosity and can produce 3D images but is inferior in the assessment of calcification.