Search tips
Search criteria 


Logo of heartHeartVisit this articleSubmit a manuscriptReceive email alertsContact usBMJ
Heart. 1998 May; 79(5): 474–480.
PMCID: PMC1728703

Enhanced dispersion of epicardial activation-recovery intervals at sites of histological inhomogeneity during regional cardiac ischaemia and reperfusion


Objective—To examine how epicardial activation and repolarisation patterns change in the course of ischaemia, and how these changes are related to the underlying histological structures.
Methods—Langendorff perfused isolated rabbit hearts were submitted to 30 minutes of left anterior descending coronary artery occlusion followed by 30 minutes of reperfusion. A 256 channel epicardial map was plotted during the various experimental phases. Activation time points were determined as t(dU/dtmin) and repolarisation time points as t(dU/dtmax). From these data the local activation-recovery interval (ARI), its dispersion (SD of ARI), and the geometry of the activation spread could be analysed. After the experiments the hearts were processed histologically and the mapping data were projected onto histological slides.
Results—There was elevation of the ST segment within the occluded area, which recovered during reperfusion. Within this area, ARI was significantly shortened and its dispersion was maximally enhanced. The enhancement of dispersion was pronounced at sites of histological inhomogeneity like fat, connective tissue, or vessels. There was also a change in the preferential direction of activation spread within the occluded zone with a marked transverse propagation of the activation wavefront, whereas under normal conditions the activation followed the longitudinal fibre axis. In addition, the total activation time in the occluded area was significantly prolonged.
Conclusions—Ischaemia alters the local activation pattern with enhanced dispersion, especially at sites of histological irregularity, transverse shift of the activation waves, and a general slowing of conduction, which may explain the increased susceptibility to arrhythmia in hearts with enhanced histological irregularities—for example, an infarct or in multi-infarcted hearts, or after myocarditis.

Keywords: dispersion;  epicardial activation-recovery interval;  ischaemia

Figure 1
(A) Schematic representation of the experimental setup and analysis. Left upper panel: mapping system with 256 unipolar electrodes. Right upper and lower panels: the principle of vector construction: from the activation time and position of the ...
Figure 2
(A) Graphically reproduced images of the left ventricular wall during control (upper panel) and after 10 minutes of regional ischaemia (lower panel) in a typical experiment. The square represents the shape of the electrode grid, while black areas ...
Figure 3
(A) QTc, calculated as ARI (activation-recovery interval)/BCL (basic cycle length), of the left ventricular wall; (B) Local dispersion of the left ventricular wall. Values are given as the means of six experiments in the course of ischaemia and reperfusion. ...
Figure 4
Activation-recovery interval (ARI) isochrones of a typical experiment. The isochrones indicate areas of ARI within the same range as given by the numbers. The graph shows the situation for the equilibration period, at two and 10 minutes of regional ...
Figure 5
Absolute number of vectors that deviate from the fibre axis between 65° and 90° during the course of the experiment. All values are given as means of six experiments. Error bars = SEM. *p < 0.05 ...

Articles from Heart are provided here courtesy of BMJ Publishing Group