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

Objective: To quantitate ventricular systolic mechanics in septic chil dren. Design: Prospective wall-stress analysis was compared to standar d ejection phase indices. Setting: University-based pediatric intensiv e care unit. Patients: Fifteen children with sepsis (hemodynamically s table, n = 5; in shock, n = 10). Measurements and Main Results: Left v entricular ejection phase indices: shortening fraction (shortening) an d corrected mean velocity of circumferential shortening (velocity) wer e adjusted for end-systolic wall stress (stress). Ejection phase, perf ormance (stress-shortening relation), contractility (stress-velocity r elation), and afterload (stress) were indexed to age-corrected normal means, with variance of greater than or equal to 2 SD regarded as sign ificant. Preload index represented variance between performance and co ntractility indices. All hemodynamically stable septic patients had no rmal performance, contractility, and preload. Afterload was increased in three of five patients. Of the patients with septic shock, six ofte n had decreased performance (decreased contractility and increased aft erload, 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 ventri cular contractility within 3 to 6 days in all four patients initially affected (p < .05). One patient developed late decreased performance a nd contractility in association with multiple organ failure. Ventricul ar loading abnormalities persisted in a followup study of these patien ts including a preload deficit in five of ten patients in shock. Concl usions: The frequency rate (40%) of reversible impaired ventricular co ntractility 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 altere d ventricular performance in the majority of children with septic shoc k, persisting days after the initiation of therapy. Wall-stress analys is provided detailed information regarding ventricular mechanics that was not otherwise obtainable by standard ejection phase indices.