Acute regional ischemia during ventricular fibrillation increased wavebreaks in the border zone (from 6.2 to 10.8) and decreased them in the ischemic zone (from 5.8 to 2.8).
Does acute regional ischemia alter the incidence and distribution of wavebreaks during ventricular fibrillation in isolated pig hearts?
Acute regional ischemia plays a dual role in maintaining ventricular fibrillation by decreasing wavebreaks in the ischemic zone while increasing them in the border zone, suggesting fixed heterogeneities predominantly drive wavebreak formation.
Absolute Event Rate: 10.8% vs 6.2%
Both fixed and dynamic heterogeneities were implicated in the mechanism of wavebreak (WB) generation during ventricular fibrillation (VF). However, their relative roles remain unclear. We hypothesized that during ischemic VF, the WBs are produced primarily because of a fixed heterogeneity; namely, the gradient of refractoriness across the ischemic border zone (BZ). Ischemia was induced in 15 isolated blood-perfused hearts by occluding the left anterior descending coronary artery. Simultaneous video imaging (approximately 32x32 mm2) of Di-4-ANEPPS fluorescence in the ischemic zone (IZ), the BZ, and the nonischemic zone (NIZ) was performed. Dominant-frequency maps were constructed to assess gradients of refractoriness during VF. We used singularity points analysis to quantify the incidence of WBs per square centimeter per second. During preischemic VF, the distribution of WBs was relatively uniform. Ischemia caused an increase of WBs in the BZ (from 6.2+/-2.8 to 10.8+/-4.0) and a decrease of WBs in the IZ (from 5.8+/-2.8 to 2.8+/-1.4), without a significant change in NIZ (from 6.4+/-2.3 to 4.1+/-1.7). This finding is fully consistent with the dominant-frequency distribution during ischemic VF: the average dominant frequency was significantly slower in IZ than in NIZ (7.8+/-0.7 versus 10.1+/-1.0 Hz), suggesting a large gradient in refractory periods across the BZ. We concluded that acute regional ischemia plays a dual role in the maintenance of VF, decreasing the incidence of WB in the IZ while increasing it in the BZ. This suggests a predominant role of fixed heterogeneities in the formation of WB during VF in acute regional ischemia.
Зайцев et al. (Thu,) conducted a other in Ventricular fibrillation and acute regional ischemia (n=15). Acute regional ischemia vs. Preischemic state was evaluated on Incidence of wavebreaks per square centimeter per second in the border zone. Acute regional ischemia during ventricular fibrillation increased wavebreaks in the border zone (from 6.2 to 10.8) and decreased them in the ischemic zone (from 5.8 to 2.8).
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