Spatial reproducibility of complex fractionated atrial electrogram depending on the direction and configuration of bipolar electrodes: an in-silico modeling study

Although 3D-complex fractionated atrial electrogram (CFAE) mapping is useful in radiofrequency catheter ablation for persistent atrial fibrillation (AF), the directions and configuration of the bipolar electrodes may affect the electrogram. This study aimed to compare the spatial reproducibility of CFAE by changing the catheter orientations and electrode distance in an in-silico left atrium (LA). We conducted this study by importing the heart CT image of a patient with AF into a 3D-homogeneous human LA model. Electrogram morphology, CFAE-cycle lengths (CLs) were compared for 16 different orientations of a virtual bipolar conventional catheter (conv-cath: size 3.5 mm, inter-electrode distance 4.75 mm). Additionally, the spatial correlations of CFAE-CLs and the percentage of consistent sites with CFAE-CL<120 ms were analyzed. The results from the conv-cath were compared with that obtained using a mini catheter (mini-cath: size 1 mm, inter-electrode distance 2.5 mm). Depending on the catheter orientation, the electrogram morphology and CFAE-CLs varied (conv-cath: 11.5±0.7% variation, mini-cath: 7.1±1.2% variation), however the mini-cath produced less variation of CFAE-CL than conv-cath (p<0.001). There were moderate spatial correlations among CFAE-CL measured at 16 orientations (conv-cath: r=0.3055±0.2194 vs. mini-cath: 0.6074±0.0733, p<0.001). Additionally, the ratio of consistent CFAE sites was higher for mini catheter than conventional one (38.3±4.6% vs. 22.3±1.4%, p<0.05). Electrograms and CFAE distribution are affected by catheter orientation and electrode configuration in the in-silico LA model. However, there was moderate spatial consistency of CFAE areas, and narrowly spaced bipolar catheters were less influenced by catheter direction than conventional catheters.

Digestion Pattern of Antihypertensive Angiotensin I-Converting Enzyme Inhibitory Peptides from Saccharomyces cerevisiae in a Successive Simulated Gastricintestinal Bioreactor

A cell-free extract of Saccharomyces cerevisiae containing the angiotensin I-converting enzyme (ACE) inhibitory peptide was treated in a successive simulated gastric-intestinal bioreactor (step 1: amylase digestion, step 2: gastric fluid digestion, step 3: intestinal fluid digestion) to illustrate the absorption pattern of antihypertensive ACE inhibitory peptide, and the ACE inhibitory activities of each step were determined. Total ACE inhibitory activities of step 1, step 2, and step 3 were 55.96%, 80.09%, and 76.77%, respectively. The peptide sequence of each steps was analyzed by MS/MS spectrophotometry. Eleven kinds of representative peptide sequences were conserved in each step, and representative new peptides including RLPTESVPEPK were identified in step 3.