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Quantitated left ventricular systolic mechanics in children with septic shock utilizing noninvasive wall-stress
T F Feltes1, R Pignatelli, S Kleinert
1Department of Pediatrics, Baylor College of Medicine, Texas Children's Hospital, Houston, TX 77030.
Insights
Forty percent of children in septic shock experience reversible impaired ventricular contractility. Decreased preload significantly impacts ventricular performance in pediatric septic shock, persisting despite therapy.
Area of Science:
- Pediatric Cardiology
- Critical Care Medicine
- Biomedical Engineering
Background:
- Sepsis in children can lead to significant cardiovascular compromise.
- Standard ejection phase indices may not fully capture complex ventricular mechanics in sepsis.
Purpose of the Study:
- To quantify ventricular systolic mechanics in children with sepsis using wall-stress analysis.
- To compare wall-stress analysis with standard ejection phase indices for assessing cardiac function in septic pediatric patients.
Main Methods:
- Prospective study involving 15 children with sepsis (5 stable, 10 in shock) in a pediatric intensive care unit.
- Utilized wall-stress analysis to assess ventricular performance, contractility, afterload, and preload.
- Compared results with age-corrected normal values, defining significant variance as >= 2 standard deviations.
Main Results:
- Hemodynamically stable septic children showed normal ventricular performance, contractility, and preload; 3/5 had increased afterload.
- In septic shock, 6/10 children had decreased performance, often linked to decreased contractility and altered afterload or preload.
- Reversible impaired ventricular contractility was observed in 40% of septic shock patients within 3-6 days; preload deficits persisted.
Conclusions:
- A significant rate (40%) of reversible impaired ventricular contractility exists in pediatric septic shock.
- Afterload is typically normal or increased, potentially due to dilation; decreased preload is a common contributor to altered ventricular performance.
- Wall-stress analysis offers detailed insights into ventricular mechanics beyond standard ejection phase indices.
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 > or = 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 of ten 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 follow-up 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.