Contribution of asynchrony and nonuniformity to mechanical interaction in normal and stunned myocardium

In anesthetized pigs, we investigated whether asynchrony (ΔT) and nonuniformity (regional differences) in contractility (ΔE) could describe the interaction between normal and stunned myocardium. Mechanical interaction was evaluated by regional postsystolic work (PSW) before and after production of stunning by a 5-min occlusion of the left circumflex coronary artery [LCX (LCX stunning)] and a subsequent 10-min occlusion of the left anterior descending coronary artery [LAD (LAD stunning)]. ΔT and ΔE were intensified by intracoronary (LAD) infusions of dobutamine. From regional end-systolic pressure-segment length relationships, systolic segment shortening (SS), end-systolic elastance (E), external work (EW), and PSW were determined. LCX stunning decreased SSLCX from 14 ± 2 (mean ± SE, n = 9) to 10 ± 2% andE LCX from 103 ± 25 to 52 ± 7 mmHg/mm, whereas the LAD region was unaffected. EWLCX decreased from 165 ± 16 to 138 ± 20 mmHg ⋅ mm, whereas PSWLCX increased from −4 ± 6 to 8 ± 3 mmHg ⋅ mm. Additional LAD st...