Key result
Feet-first patient orientation significantly reduced maximum lead-tip heating for right ventricular leads at the MRI isocenter compared to head-first orientation (1.6°C vs 32.0°C; P=0.008).
Why the study?
The study evaluated changes in patient orientation to mitigate radiofrequency-induced lead-tip heating during MRI.
Does feet-first orientation reduce radiofrequency-induced lead-tip heating compared to head-first orientation for cardiac AIMDs during MRI?
Does feet-first orientation reduce radiofrequency-induced lead-tip heating compared to head-first orientation for cardiac AIMDs during MRI?
Absolute Event Rate: 1.6% vs 32%
p-value: p=0.008
Changing patient orientation to feet-first during MRI significantly reduces radiofrequency-induced lead-tip heating for patients with anterior left-sided cardiac AIMDs.
Feet-first orientation reduced lead-tip heating in this animal model; hypothesis-generating for human cardiac AIMD MRI safety.
Purpose To evaluate changes in patient orientation to mitigate radiofrequency-induced lead-tip heating (LTH) during MRI. Materials and Methods LTH was evaluated for device type, lead path, and distance to the isocenter of a 1.5-T MRI system. LTH for 378 conditions in both head-first (HF) and feet-first (FF) orientations was measured for nine MRI-unsafe cardiac active implantable medical devices (AIMDs) placed along three (two anatomic, one planar) left-sided lead paths at nine landmark locations. The devices were exposed to 5 minutes of continuous radiofrequency energy at 4 W/kg whole-body specific absorption rate. Results LTH was greater in HF than in FF orientation for the planar and one anatomic lead path (P < .05). LTH was significantly affected by lead path, distance to isocenter, and patient orientation (all P < .05), but not by cardiac AIMD device type. Maximum LTH was observed in an HF orientation for the planar lead path when the lead tip was at isocenter (right ventricular [RV] lead: 32.0 °C ± 16.3 [standard deviation], right atrial [RA] lead: 16.1°C ± 9.3). In the FF orientation, LTH was significantly reduced (RV lead: 1.6°C ± 1.4; mean RA lead: 0.5°C ± 1.0; P = .008). Conclusion LTH for supine FF patient orientations among patients with anterior left-sided cardiac AIMDs can be significantly lower than LTH for supine HF orientations. There was no scenario in which LTH was significantly worse in the FF position. Changing patient orientation is a simple method to reduce radiofrequency-induced LTH.
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Martinez et al. (2019) studied MRI-unsafe cardiac active implantable medical devices (n=9). Feet-first (FF) orientation vs. Head-first (HF) orientation was evaluated on Maximum lead-tip heating (LTH) for right ventricular lead at isocenter (p=0.008). Feet-first patient orientation significantly reduced maximum lead-tip heating for right ventricular leads at the MRI isocenter compared to head-first orientation (1.6°C vs 32.0°C; P=0.008).
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