Abstract MP164: Electrophysiologic Conservation of Epicardial Conduction Dynamics After Myocardial Infarction in Newborn Piglets

Introduction: Newborn piglets reportedly exhibit natural heart regeneration after myocardial infarction (MI). However, the electrophysiologic properties of this regenerated muscle have not been examined. We hypothesized that epicardial electrical conduction is preserved after MI in newborn piglets. Methods: Yorkshire-Landrace piglets underwent left anterior descending coronary artery ligation on postnatal day 1 (P1, n=4) or postnatal day 7 (P7, n=7), infarcting the anteroseptal left ventricle through which the Purkinje conduction system passes. After 7 weeks, cardiac magnetic resonance imaging (MRI) was performed with late gadolinium enhancement for fibrosis analysis. Epicardial conduction mapping was performed using custom 3D-printed, 256-channel high-resolution mapping arrays (Fig 1A). Age- and weight-matched healthy pigs served as controls (n=7). Data are expressed as mean±SD. Results: MRI analysis revealed significant differences between the control, P1, and P7 groups in ejection fraction (47.6±3.1% vs 37.6±3.3% vs 30.2±6.6%, p<0.001, Fig 1B) and the degree of transmural anteroseptal LV scar (0.0±0.0% vs 9.1±5.4% vs 15.4±4.2%, p<0.001), respectively. Evidence of infarcted myocardium was identified with high-resolution mapping in the P1 and P7 piglets (black arrows, Fig 1C-F). Epicardial electrical conduction was preserved in control and all P1 pigs (Figs 1C-D), whereas variable conduction block or aberrant propagation were observed in all P7 pigs (Fig 1E-F, p=0.001). Conclusion: P1 piglets exhibited incomplete natural cardiac regeneration after MI but nevertheless demonstrated electrophysiologic conservation of epicardial conduction dynamics.

Download Full-text

Spatial and temporal variations in pacemaking and conduction in the isolated renal pelvis

AJP Renal Physiology ◽

10.1152/ajprenal.1996.270.4.f567 ◽

1996 ◽

Vol 270 (4) ◽

pp. F567-F574 ◽

Cited By ~ 3

Author(s):

W. J. Lammers ◽

H. R. Ahmad ◽

K. Arafat

Keyword(s):

High Resolution ◽

Renal Pelvis ◽

Refractory Period ◽

Conduction Block ◽

Temporal Variations ◽

The Body ◽

High Resolution Mapping ◽

Resolution Mapping ◽

Preceding Interval ◽

And Behavior

In renal pelvis preparations isolated from the sheep, the location of the pacemaker and the pathway of conduction of the electrical impulse in the pelvis were analyzed in detail. An electrophysiological acquisition system was used allowing simultaneous recordings from 240 extracellular electrodes. Reconstruction of the spread of activity showed that the site of the pelvis pacemaker was, in virtually all cases, located at the pelvicalyceal border and never in the body of the pelvis or in the area of the pelviureteric junction. One single pacemaker was responsible for a particular spread of activation, and fusion of activity originating from two or more pacemakers did not place. Furthermore, spontaneous shifts of the pacemaker could occur from one site to another along the pelvicalyceal border. Conduction from the site of the current pacemaker to the pelviureteric junction and the ureter was slow, inhomogeneous, and contorted. Multiple instances of partial or total conduction block were seen at all levels in the pelvis and were not restricted to the pelviureteric junction. The occurrence of the conduction block did not seem to be related to the length of the preceding interval, implying that the refractory period did not play a major role in the genesis of intrapelvic conduction block. In conclusion, high-resolution mapping of the renal pelvis is possible and reveals location and behavior of the pacemaker and documents inhomogeneities in conduction and conduction block.

Download Full-text

High‐Resolution Mapping and Ablation of Atrial Tachycardias Involving the Lateral Left Atrium

Journal of the American Heart Association ◽

10.1161/jaha.121.022384 ◽

2021 ◽

Author(s):

Shinsuke Miyazaki ◽

Kanae Hasegawa ◽

Kazuya Yamao ◽

Moe Mukai ◽

Daisetsu Aoyama ◽

...

Keyword(s):

High Resolution ◽

Left Atrium ◽

Superior Vena ◽

Conduction Block ◽

Vena Cava ◽

Atrial Tachyarrhythmias ◽

High Resolution Mapping ◽

Complex Anatomy ◽

Resolution Mapping

Background The lateral left atrium (LA) is often associated with atrial tachycardia (AT) because of its complex anatomy. We sought to characterize ATs associated with the lateral LA, including the posterolateral mitral isthmus (MI) and left atrial ridge. Methods and Results Twenty‐eight lateral LA‐associated ATs were mapped with high‐resolution mapping systems and entrainment pacing. The vein of Marshall was mapped with a 1.8‐Fr mapping catheter when possible. ATs were associated with the posterolateral MI in 18 ATs (14 perimitral, 3 small reentry, and 1 focal AT). All patients had undergone MI area ablation, and all ATs were successfully eliminated. During 27.0 (interquartile range, 10.5–40.0) months of follow‐up, all were free from any atrial tachyarrhythmias, with 3 patients on antiarrhythmics. Of 10 ATs involving the ridge or Marshall bundle, 3 were ridge related, 3 were Marshall bundle related based on vein of Marshall mapping, and 1 was a persistent left superior vena cava related AT. All 7 patients had undergone MI linear ablation. The critical isthmus was in the LA‐ridge junction or the LA‐Marshall bundle junction. Bidirectional conduction block between the LA and ridge or Marshall bundle was created. Two patients had the critical isthmus in the other area. The remaining patient had micro‐reentry in the ridge. All 10 ATs were terminated during ablation at the critical isthmus. During 12.0 (5.2–31.7) months of follow‐up, all were free from any atrial tachyarrhythmias, with 7 patients on antiarrhythmics. Conclusions Most ATs occurred after MI area ablation. An high resolution mapping‐guided approach is highly effective for identifying the mechanism.

Download Full-text