Safety considerations during transapical aortic valve implantation

Transcatheter aortic valve implantation (TAVI) is a new method for the treatment of very high-risk patients with aortic valve stenosis. The radiation dose to which the patient and each member of the heart team are exposed during this new fluoroscopically guided intervention is unknown.

Between April 2008 and August 2013, 1177 consecutive patients underwent transapical TAVI (TA-TAVI). In 22 consecutive patients undergoing TA-TAVI, the radiation doses to the cardiothoracic surgeon, cardiologist, anaesthesiologist (performing echocardiography examination), surgical assistant and nurse were measured. The radiation dose measurements were performed during TAVI using thermoluminescence and film dosimeters positioned on seven parts of the body: (i) chest above the lead apron, (ii) pelvic area below the apron, (iii) chest below the apron, (iv) thyroid gland above the apron, (v) near eyes, (vi) hands (using rings) and (vii) the feet. The results were compared with the values given in the international literature on recommended radiation dose limits for workers.

The mean radiation time was 6.1 min and the mean dose-area product for the patients was 8.661 µGy · m(2). Analysis of the dosimeters and the calculation of the effective dose showed a per intervention dose of 0.03 mSv for the surgeon, 0.05 mSv for the assistant, 0.02 mSv for the cardiologist and the anaesthesiologist and 0.001 mSv for the nurse. The maximum ionizing radiation per intervention was 0.5 mSv at the right hand of the surgeon (holding the introducer sheet) and 0.7 mSv at the left hand of the surgical assistant. Additionally, the analysis of the body dose shows a maximum dose to the lower leg of the surgeon (0.3 mSv) and the genital area of the assistant (0.06 mSv).

During a TA-TAVI procedure, the patients receive a higher X-ray dose than during coronary angiography with intervention. After 100 TAVI procedures, the members of the heart team sustain a comparable dose of ionizing radiation to the annual dose received by a busy interventional cardiologist. Therefore, maximal safety and optimal X-ray protection for patients and the members of the team are crucial and should be redefined.