Key result
Lower atmospheric pressure yields smaller ablation lesions and increases steam pops to ~5%.
Why the study?
Atmospheric pressure affects the boiling point of water and may influence thermal lesion formation during radiofrequency (RF) ablation, but whether it alters RF lesion formation and steam-pop risk under fixed ablation index (AI) targets remained unknown.
Does lower atmospheric pressure at high altitudes alter radiofrequency ablation lesion dimensions and steam-pop occurrence under fixed ablation index targets in an ex vivo porcine heart model?
Does lower atmospheric pressure at high altitudes alter radiofrequency ablation lesion dimensions and steam-pop occurrence under fixed ablation index targets in an ex vivo porcine heart model?
This ex vivo study demonstrates that natural high-altitude hypobaric conditions result in shallower, smaller-volume radiofrequency ablation lesions and a higher rate of steam pops at fixed ablation index targets, suggesting that environmental atmospheric pressure may affect ablation biophysics.
Answers are grounded in this paper and cite their sources.
High-altitude hypobaria may increase steam-pop risk and reduce lesion depth at fixed AI; leaves open need for adjusted targets in clinical studies.
Background Atmospheric pressure affects the boiling point of water and may influence thermal lesion formation during radiofrequency (RF) ablation. However, whether atmospheric pressure alters RF lesion formation and steam-pop risk under fixed ablation index (AI) targets remains unknown. Methods A total of 360 analyzable lesions were created in 36 ex vivo porcine hearts using the same RF ablation system, which was transported and used consistently at three sites with different atmospheric pressures: Beijing (1,014 hPa), Xining (770 hPa), and Lhasa (650 hPa). At each site, 30 analyzable lesions were obtained at each target AI value (300, 400, 500, and 600). Lesion dimensions, impedance reduction, ablation duration, temperature, and steam-pop occurrence were recorded. Differences among sites were assessed using analysis of variance and Fisher's exact test. A multiple linear regression model was constructed to evaluate the relationship between atmospheric pressure, AI, and lesion volume. Results At fixed AI targets, lesions created at lower-pressure sites were significantly shallower and had smaller volumes (all P < 0.05), whereas surface and maximum diameters remained similar among the three sites. Steam pops occurred in 0/120 (0.0%) RF applications in Beijing, 2/122 (1.6%) in Xining, and 6/126 (4.8%) in Lhasa (overall P = 0.031). Impedance reductions differed significantly among sites at 3 and 10 s (both P < 0.001), but not at 5 s ( P = 0.498). Atmospheric pressure and AI jointly explained 88.4% of the variation in lesion volume (R 2 = 0.884), enabling derivation of a hypothesis-generating AI correction equation. Conclusion Within the natural range of atmospheric pressures examined, lower atmospheric pressure was associated with shallower and smaller-volume RF lesions at fixed AI targets and a higher observed incidence of steam pops. These findings suggest that atmospheric pressure may influence RF lesion formation and steam-pop occurrence, warranting further mechanistic and in vivo validation.
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Li et al. (2026) studied Radiofrequency catheter ablation lesion formation (n=360). Radiofrequency ablation under lower atmospheric pressure (Xining 770 hPa and Lhasa 650 hPa) at fixed ablation index targets (300, 400, 500, 600) vs. Radiofrequency ablation at near sea-level atmospheric pressure in Beijing (1,014 hPa) at identical fixed ablation index targets was evaluated on Lesion depth, lesion volume, and steam-pop occurrence at fixed ablation index targets (p=0.031). Lower atmospheric pressure resulted in significantly shallower, smaller-volume lesions (P < 0.05) and more steam pops (4.8% at 650 hPa vs 0.0% at 1,014 hPa, P = 0.031) at fixed AI targets.
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