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Although ablation energy (AE) and force-time integral (FTI) are well-known active predictors of lesion characteristics, these parameters do not reflect passive tissue reactions during ablation, which may instead be represented by drops in local impedance (LI). This study aimed to investigate if additional LI data improves predicting lesion characteristics and steam pops. RF applications at a range of powers (30 W, 40 W, and 50 W), contact forces (8 g, 15 g, 25 g, and 35 g), and durations (10–180 s) using perpendicular/parallel catheter orientations were performed in excised porcine hearts (N = 30). The correlation between AE, FTI, and lesion characteristics was examined, and the impact of LI (%LI drop (%LID) defined by the ΔLI divided by the initial LI) was additionally assessed. Three hundred seventy-five lesions without steam pops were examined. Ablation energy (W × s) and FTI (g × s) showed a positive correlation with lesion depth (ρ = 0.824:P < 0.0001 and ρ = 0.708:P < 0.0001), surface area (ρ = 0.507:P < 0.0001 and ρ = 0.562:P < 0.0001), and volume (ρ = 0.807:P < 0.0001 and ρ = 0.685:P < 0.0001). %LID also showed a positive correlation individually with lesion depth (ρ = 0.643:P < 0.0001), surface area (ρ = 0.547:P < 0.0001), and volume (ρ = 0.733:P < 0.0001). However, the combined indices of AE × %LID (AE multiplied by %LID) and FTI × %LID (FTI multiplied by %LID) provided significantly stronger correlation with lesion depth (ρ = 0.834:P < 0.0001 and ρ = 0.809:P < 0.0001), surface area (ρ = 0.529:P < 0.0001 and ρ = 0.656:P < 0.0001), and volume (ρ = 0.864:P < 0.0001 and ρ = 0.838:P < 0.0001). This tendency was observed regardless of the catheter placement (parallel/perpendicular). AE (P = 0.02) and %LID (P = 0.002) independently remained as significant predictors to predict steam pops (N = 27). However, the AE × %LID did not increase the predictive power of steam pops compared to the AE alone. LI, when combined with conventional parameters (AE and FTI), may provide stronger correlation with lesion characteristics.

Background Sinus of Valsalva aneurysm (SVA) is a rare cardiac abnormality occurring in 0.09% of the general population, but few reports have examined its recurrence. Unruptured SVAs are usually asymptomatic. Case summary A 50-year-old woman presented with chest pain and a history of surgery for a ruptured right coronary SVA 32 years prior. Echocardiography showed the recurrence of an unruptured SVA of the non-coronary sinus with moderate aortic regurgitation, severe mitral regurgitation, and severe tricuspid regurgitation. Cardiac computed tomography (CT) revealed compression of the right coronary artery (RCA) between the SVA and sternum. Adenosine triphosphate stress myocardial perfusion imaging (MPI) identified reversible ischaemia of the inferior wall. The patient underwent patch closure of the SVA, aortic valve replacement, mitral valvuloplasty, and tricuspid annuloplasty. Post-operative MPI showed no residual ischaemia, and CT confirmed both successful repair of the SVA and intact RCA. Discussion This case provides two noteworthy findings. First, the SVA recurred after 32 years. Second, a non-coronary SVA causing myocardial ischaemia is extremely rare given the long anatomical distance between the non-coronary sinus and coronary arteries. In our patient, the non-coronary SVA grew large enough within the anterior mediastinum to cause RCA compression.

Clinical implication of local impedance (LI) for radiofrequency (RF) ablation has not been fully established. This study aimed to investigate this point using IntellaNav MiFi OITM catheter. LI and generator impedance drops (ΔLI and ΔGI) were evaluated in excised porcine hearts (N = 16) during RF applications at a range of powers (30 and 50 W), contact forces (5–40 g), and durations (10–180 s) using perpendicular or parallel catheter orientation. Additionally, temporal LI changes were assessed. Of the 240 lesions without steam pops (92.3%), ΔLI showed better correlations with lesion surface area (ρ = 0.55 vs 0.36, P = 0.004), maximum depth (ρ = 0.53 vs 0.14, P < 0.001), and lesion volume (ρ = 0.64 vs 0.23, P < 0.001) than ΔGI. Furthermore, %LI-drop (ΔLI/initial LI) demonstrated stronger correlations with lesion surface area (ρ = 0.60 vs 0.55, P < 0.001), maximum depth (ρ = 0.57 vs 0.53, P < 0.001), and volume (ρ = 0.69 vs 0.64, P < 0.001) than ΔLI. Parallel catheter orientation improved correlation of ΔLI with lesion surface area (ρ = 0.63 vs 0.40, P = 0.015) and depth (ρ = 0.68 vs 0.45, P = 0.008) and created a larger surface lesion (36.3[29.2–42.7] mm2 vs 28.8[21.6–34.2] mm2, P < 0.001) than the perpendicular. LI of the lesions significantly differed between baseline, immediately after RF, and 5 min after (P < 0.01). LI reaching plateau, larger initial LI, ΔLI, and %LI-drop, and larger RF power and longer duration were observed in pop lesions (P < 0.05). %LI-drop demonstrated a better correlation with lesion size than ΔLI. LI may be used as an additional parameter to predict lesion size and steam pops. Temporal variation and catheter orientation should be considered to interpret LI.

Background: D-serine, the enantiomer of L-serine, was identified in mammals 20 years ago. Although a close relationship between D-serine and renal dysfunction has been shown, the clinical implications of urinary D- and L-serine in humans are poorly understood. The aim of this study was to evaluate the relationship between urinary D- and L-serine with well-known renal biomarkers, and clarify the prognostic value of D- and L-serine for renal events. Methods: This cross-sectional, prospective study included 65 patients with atherosclerotic risk factors, who were followed up for a median of 16 months. The primary endpoint was a composite of end-stage renal disease and a decline in estimated glomerular filtration rate (eGFR) ≥ 25% from baseline. Results: Urinary D-serine concentrations showed a better correlation with eGFR than did urinary L-serine, whereas neither urinary D- nor L-serine correlated with tubular markers such as urinary liver-type fatty acid-binding protein and N-acetyl-beta-D-glucosaminidase. A Cox regression analysis revealed that low urinary D-serine levels were significantly associated with the primary endpoint after adjusting for confounding factors (hazard ratio 12.60; 95% confidence interval, 3.49–45.51). Conclusions: Urinary D-serine is associated with glomerular filtration and can be a prognostic biomarker of renal dysfunction in patients with atherosclerotic risk factors.