Electrophysiological and histological characterization of atrial scarring in a model of isolated atrial myocardial infarction

FIGURE 1. Illustration of the experimental procedure and study specimen preparations. (A) Fluoroscopic image of one studied pig showing the catheter balloon located in the proximal segment of the LCX while deploying the covered stent (white arrow). (B) Photograph showing the anatomical relationship between the left ventricle (LV), left atrium (LA) and the left circumflex coronary artery (LCX) where the covered stent was deployed. (C) Microphotograph of a histological preparation (frontal section) showing both areas of infarct infarcted (dashed arrows) and non-infarcted areas (solid arrows) in the left atrial appendage with preserved left ventricular myocardium (white arrows) corresponding to the annular area.

FIGURE 2. Electroanatomical voltage and multifrequency impedance maps of the left atrium and histological preparations of the explanted hearts of four representative pigs submitted to acute transcatheter occlusion of the atrial coronary artery branches arising from the proximal segment of the left circumflex coronary artery, with preserved left ventricular myocardium. The figure shows a correspondence between endocardial areas of low voltage and impedance and location of infarct zones.

FIGURE 3. Electroanatomical voltage and multifequency maps and corresponding signals in two representative pigs. The upper panel shows the electroanatomical maps and the corresponding multifrequency impedance, ECG, local bipolar and unipolar signals in two selected sites (A,B) in a pig with acute transcatheter occlusion of the atrial coronary artery branches arising from the proximal segment of the left circumflex coronary artery. The lower panel shows the electroanatomical maps and the corresponding signals in two selected sites (A,B) in a control pig non-submitted to atrial coronary branch occlusion. LAA: Left atrial appendage; MA: Mitral annulus; PV: Pulmonary vein.

FIGURE 4. Mean values of the impedance magnitude and phase angle at multifrequency in 6 pigs submitted to acute transcatheter occlusion of the atrial coronary artery branches arising from the proximal segment of the left circumflex coronary artery. The left panels show the mean changes in atrial myocardial impedance magnitude (upper) and phase angle (lower at 26 studied current frequencies. The right panels show the mean changes in atrial myocardial impedance magnitude (upper) and phase angle (lower) at four selected current frequencies. NZ: normal zone; IZ: infarcted zone; ***: ANOVA p < .001 between myocardial impedance NZ and IZ areas.

FIGURE 5. Variability of median values of phase angle of atrial tissue electrical impedance at 307 kHz and bipolar voltage of local atrial electrograms. Data are represented in box and whisker plots. Boxes represent 25th to 75th quartiles; horizontal lines within boxes represent the median; whiskers represent the minimum and maximum values.