Fig 1.
(A) Internal Cardiac Monitor Device. (B) Pacemaker Device. (C) Programmer (Medtronic 2090) sets regular, rapid atrial overdrive pacing parameters on the pacemaker (400-600 bpm, 8V). (D) The programmer (Medtronic CareLink Encore) is used to record frozen strips and episodes from the Internal Cardiac Monitor, which constitutes Internal Cardiac Monitor reports.
Fig 2.
Medtronic Rapid Atrial Pacing System.
A pacing wire is inserted into the right atrial appendage and connected to a pacing generator implanted in the lateral neck wall muscle. A programmer, Medtronic CareLink 2090, controlled the pacing generator and internal cardiac monitor wirelessly. https://biorender.com/mngrgm4.
Fig 3.
Activity levels 24/7 were tracked using Fitbark collars worn by the swine as illustrated above.
Fig 4.
Cardiac Monitoring by Electrocardiograms.
Electrocardiogram strip extracted from implanted cardiac monitor displaying. Normal Sinus Rhythm, Paced Rhythm, and Atrial Fibrillation (AFib).
Fig 5.
Kaplan-Meier curve depicting the proportion of pigs remaining free from induced AFib over this observation period (n = 6). Four of six pigs (67%) successfully converted to AFib during the study period, with conversions occurring at 14-, 94-, 105-, and 108-days post-induction attempt. Two pigs (33%) did not develop AFib during the observation window. The stepped curve represents individual AFib induction events, with the y-axis showing the proportion of subjects not yet induced into AFib and the x-axis showing time in days.
Fig 6.
Hourly activity levels, tracked using Fitbark collars show a significant decrease during AFib episodes compared to baseline, mirroring human symptoms like fatigue and exercise intolerance. #P < 0.01, *P < 0.05 refers to persistent AFib versus baseline.
Fig 7.
Histopathological Analysis of persistent AFib tissue. Masson’s trichrome staining of left and right atrial biopsies were imaged and analyzed for blue/red positive staining in ImageJ.
Swine that were induced into persistent atrial fibrillation displayed increased collagen staining and significantly reduced muscle staining (P < 0.05) and (P < 0.001).