QUANTITATED LEFT-VENTRICULAR SYSTOLIC MECHANICS IN CHILDREN WITH SEPTIC SHOCK UTILIZING NONINVASIVE WALL-STRESS ANALYSIS

Objective: To quantitate ventricular systolic mechanics in septic children. Design: Prospective wall-stress analysis was compared to standard ejection phase indices. Setting: University-based pediatric intensive care unit. Patients: Fifteen children with sepsis (hemodynamically stable, n = 5; in shock, n = 10). Measurements and Main Results: Left ventricular ejection phase indices: shortening fraction (shortening) and corrected mean velocity of circumferential shortening (velocity) were adjusted for end-systolic wall stress (stress). Ejection phase, performance (stress-shortening relation), contractility (stress-velocity relation), and afterload (stress) were indexed to age-corrected normal means, with variance of greater than or equal to 2 SD regarded as significant. Preload index represented variance between performance and contractility indices. All hemodynamically stable septic patients had normal performance, contractility, and preload. Afterload was increased in three of five patients. Of the patients with septic shock, six often had decreased performance (decreased contractility and increased afterload, n = 4; decreased afterload, n = 1; and severe preload deficit, n = 1). Despite aggressive volume resuscitation, six of ten children in septic shock had evidence of diminished preload. Follow-up studies in the septic shock patients demonstrated reversal of depressed ventricular contractility within 3 to 6 days in all four patients initially affected (p < .05). One patient developed late decreased performance and contractility in association with multiple organ failure. Ventricular loading abnormalities persisted in a followup study of these patients including a preload deficit in five of ten patients in shock. Conclusions: The frequency rate (40%) of reversible impaired ventricular contractility in children with septic shock is significant. Afterload is normal or increased in the majority of septic subjects, possibly due to acute ventricular dilation. Decreased preload contributes to altered ventricular performance in the majority of children with septic shock, persisting days after the initiation of therapy. Wall-stress analysis provided detailed information regarding ventricular mechanics that was not otherwise obtainable by standard ejection phase indices.