E. Coli Sepsis Induces Profound Mechanoenergetic Inefficiency in the Porcine Left Ventricle

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Abstract
Myocardial dysfunction is believed to be a central part of septic multiorgan manifestations. The aim of the present study was to assess whether E. coli sepsis in an in vivo model would induce a dysfunction in the relationship between mechanical work and energy consumption in the left ventricle (LV). Accordingly, we measured hemodynamics, left ventricular pressure–volume area (PVA), and myocardial oxygen consumption (MVo2) in deeply anesthetized pigs. Eight pigs received 2.0 ± 0.5 × 109E. coli bacteria intravenously, and seven served as controls. Compared with baseline and the control group, no alternations were observed in LV diastolic function or indices of contractility in the septic group. The MVo2–PVA relationship was highly linear in both groups (all r2 = 0.96–0.99). At 5 h, the y-axis intercept of the MVo2–PVA relationship (nonmechanical MVo2) had increased in the sepsis group by 70% compared with baseline (P = 0.004) and by 60% compared with the control group (P = 0.003). Contractile efficiency (the inverse of the MVo2–PVA slope) remained unchanged over time and between groups. The study demonstrates a profound increase in nonmechanical oxygen consumption during E. coli sepsis in the LV.