Depression of left ventricular performance during canine splanchnic artery occlusion shock

We studied canine left ventricular contractile performance following splanchnic artery occlusion (SAO) shock. We evaluated contractile performance by analyzing the left ventricular end systolic pressure-diameter relationship (sigma ES) because we have previously shown that sigma ES is independent of large changes in preload, afterload, and heart rate but sensitive to changes in ventricular contractility. Following release from 2 hours of SAO, seven dogs survived, five expired immediately, and ten expired between 0.5 and 3.5 hours (termed nonsurvivors, [NS]). The NS dogs exhibited slight tachycardia, slight increase in total peripheral resistance, marked decreases in +dP/dt, cardiac output, arterial blood pressure, stroke volume, and stroke work. Ventricular performance (sigma ES) declined with time following SAO release in the nonsurviving dogs; in contrast, surviving animals exhibited an augmentation of sigma ES during SAO and following SAO release. Sham dogs exhibited no time-dependent changes in sigma ES. The dogs that expired immediately following SAO release exhibited a precipitous decline in sigma ES from 43.0 +/- 9.0 to 23.0 +/- 4.8 mm Hg/mm within minutes of SAO release. We analyzed these data by Cox multiple regression analysis to determine the major covariates of survivability. The analysis revealed that sigma ES at the midpoint in time between SAO release and death was best correlated with the survival function. These results suggest that cardiovascular collapse of SAO shock is associated with an early and sustained loss of ventricular contractility.