Risks Related To Fluoroscopy Radiation Associated With Electrophysiology Procedures

Abstract

The benefits of cardiac imaging are immense, and modern cardiac electrophysiology (EP) requires the extensive and versatile use of a variety of cardiac imaging and radiology-based techniques. In the cardiac electrophysiology lab, doses can range around a reference effective dose (ED) of 15 milliSievert corresponding to 750 chest x-rays for a cardiac radiofrequency ablation, ranging from less than 2 to > 60 mSv. The reference dose for a regular pacemaker or ICD implant is 4 mSv (range 1.4-17) and for a CRT implant is 22 mSv (range 2.2-95). Doses on the order of magnitude of 10-100 milliSievert (mSv) correspond to a low (albeit definite, not negligible) additional lifetime risk of fatal and non-fatal cancer from between 1 in 1000 (10 mSv) to 1 in 100 (100 mSv). The increasing use and complexity of cardiac electrophysiology techniques have not been matched by increasing awareness and knowledge by prescribers and practitioners. The protection of doctors is just as important as protection of patients. Most experienced (and most exposed) interventional cardiologists and electrophysiologists have an exposure per annum of around 5 mSv, two to three times higher than diagnostic radiologists, with a typical cumulative lifetime attributable risk on the order of magnitude of 1 cancer (fatal and non-fatal) per 100 exposed subjects. Operator dose per procedure correlates somewhat with the patient dose, but may be typically 1000 times lower depending upon the shielding employed (one unit of incidence scatter dose for the operator when 1000 units of incident dose are given to the patient). However, adequate radiation protection training and diligent protection can reduce this radiation exposure by 90%. The priority given to radioprotection in every cardiology department is an effective strategy for primary prevention of cancer, a strong indicator of the quality of the cardiology division, and the most effective shielding for enhancing the safety of patients, doctors, and staff.

Keywords: Electrophysiology; Radiation; Risk.

Figure 1.. The dose-effect relationship between radiation exposure and cancer risk over background levels. The solid line indicates the epidemiological evidence, which is conclusive for doses > 50 mSv, and recently expanded with the publication of two medical cohorts of over 800,000 children who underwent CT in Australia and UK. The cumulative dose of 100 mSv corresponds to a 1% extra-risk of cancer over baseline and can be reached after three serial EP procedures and two CTs.

Figure 2.. The risk model for the Biological Effects of Ionizing Radiation Committee VII for exposure to low-level radiation predict that about one (red star) out of 100 people would likely develop solid cancer or leukemia from an exposure of 100 mSv above background. About 42 additional people (yellow circles) in the same group would be expected to develop solid cancer or leukemia from other causes. Roughly half of these cancers would result in death. This dose of 100 mSv is reached by 5% of patients in a single cardiac ablation or coronary angiography procedure. [Modified and adapted from ref 6: BEIR VII Health Risks from Exposure to Low levels of Ionizing Radiation, Phase 2. dels-old.nas.edu/dels/rpt_briefs/beir_vii_final.pdf.]