Andrew Goldsweig (Division of Cardiology, University of Nebraska Medical Center, Omaha, USA) and others report in Catheterization and Cardiovascular Interventions that eight factors are associated with increased dose-area product (DAP) during transcatheter aortic valve implantation (TAVI)—including cutdown transfemoral access (vs. percutaneous access). They observe modification of procedural technique may facilitate reduction in radiation exposure.
Goldsweig et al comment that when TAVI was restricted to extreme risk or inoperable patients, radiation exposure was less of a concern because their life expectancies “preclude significant stochastic risk of malignancy related to procedural radiation”. However, they add that radiation exposure is becoming “increasingly important” now that TAVI is starting to be used in lower risk populations (and thus younger patients). “Younger patients are likely to live long enough to experience degeneration of their bioprosthetic valves, necessitating repeated valve-in-valve TAVI procedures,” the authors write. Therefore, according to Goldsweig et al, “the stochastic risk of radiation-related malignancy may be significant” in younger patients undergoing repeated fluoroscopy and CT scanning for TAVI procedures.
As few data are available for patient radiation exposure during TAVI, the authors sought to “identify those factors that influence radiation exposure during TAVI procedures and to quantify their relative impact”. After retrospective reviewing data from patients who underwent TAVI at their centre (Rhode Island Hospital, Providence, USA), they identified 294 TAVI procedures and found that the average DAP was 169Gy*cm2. Eight factors were associated with increased radiation exposure: increased patient weight, cutdown transfemoral vs. percutaneous access, transapical vs percutaneous transfemoral, preprocedural creatinine, prohibitive surgical risk vs. high risk, vascular complications, preprocedure haemoglobin and prior aortic valve replacement.
Goldsweig et al observe that some of these factors have been previously recognised as predictors of increased radiation exposure (ie patient weight) but note that other factors are novel. They say: “Our findings of increased radiation usage with cutdown vs. percutaneous transfemoral access contrast with those previously reported from an earlier era of TAVI in which cutdown access was the standard of care. In this study, we believe that cutdown access may reflect significant vascular disease seen on preprocedural computed tomography scan: such disease may increase procedural complexity and, therefore, increase radiation.”
Concluding, the authors note that “modification of procedural technique, especially using percutaneous femoral vascular access, may facilitate reduction in exposure.”
Goldsweig told Cardiovascular News: “We found that factors associated with increased procedural complexity, radiation attenuation and scatter were linked to increased patient radiation exposure, while use of percutaneous (vs. cutdown) femoral vascular access was associated with less patient radiation exposure during TAVI. As always, TAVI operators can reduce radiation exposure their patients and themselves by minimising beam time, maximising distance from the source, and maximizing shielding.”