title: Associations among left ventricular systolic function, tachycardia, and cardiac preload in septic patients.
abstract: BACKGROUND
  In sepsis, tachycardia may indicate low preload, adrenergic stimulation, or both. Adrenergic overstimulation is associated with septic cardiomyopathy. We sought to determine whether tachycardia was associated with left ventricular longitudinal strain, a measure of cardiac dysfunction. We hypothesized an association would primarily exist in patients with high preload.
  
  
  METHODS
  We prospectively observed septic patients admitted to three study ICUs, who underwent early transthoracic echocardiography. We measured longitudinal strain using speckle tracking echocardiography and estimated preload status with an echocardiographic surrogate (E/e'). We assessed correlation between strain and heart rate in patients with low preload (E/e' < 8), intermediate preload (E/e' 8-14), and high preload (E/e' > 14), adjusting for disease severity and vasopressor dependence.
  
  
  RESULTS
  We studied 452 patients, of whom 298 had both measurable strain and preload. Abnormal strain (defined as >-17%) was present in 54%. Patients with abnormal strain had higher heart rates (100 vs. 93 beat/min, p = 0.001). After adjusting for vasopressor dependence, disease severity, and cardiac preload, we observed an association between heart rate and longitudinal strain (β = 0.05, p = 0.003). This association persisted among patients with high preload (β = 0.07, p = 0.016) and in patients with shock (β = 0.07, p = 0.01), but was absent in patients with low or intermediate preload and those not in shock.
  
  
  CONCLUSIONS
  Tachycardia is associated with abnormal left ventricular strain in septic patients with high preload. This association was not apparent in patients with low or intermediate preload.
authors.affiliation: Critical Care Echocardiography Service, Intermountain Medical Center, 5121 S Cottonwood St, Murray, UT, 84157, USA. Michael.Lanspa@imail.org.|Division of Pulmonary and Critical Care Medicine, University of Utah, 30 N 1900 E, 701 Wintrobe, Salt Lake City, UT, 84132, USA. Michael.Lanspa@imail.org.
authors.forename: Michael J
authors.identifier: http://orcid.org/0000-0003-0968-4755
authors.initials: MJ
authors.lastname: Lanspa
authors.affiliation: Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Boston, MA, USA.|Department of Anesthesia and Critical Care, University of Chicago, 5841 South Maryland Avenue, Chicago, IL, 60637, USA.
authors.forename: Sajid
authors.initials: S
authors.lastname: Shahul
authors.affiliation: Division of Pulmonary and Critical Care Medicine, University of Utah, 30 N 1900 E, 701 Wintrobe, Salt Lake City, UT, 84132, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Hersh
authors.affiliation: Critical Care Echocardiography Service, Intermountain Medical Center, 5121 S Cottonwood St, Murray, UT, 84157, USA.
authors.forename: Emily L
authors.initials: EL
authors.lastname: Wilson
authors.affiliation: Critical Care Echocardiography Service, Intermountain Medical Center, 5121 S Cottonwood St, Murray, UT, 84157, USA.
authors.forename: Troy D
authors.initials: TD
authors.lastname: Olsen
authors.affiliation: Critical Care Echocardiography Service, Intermountain Medical Center, 5121 S Cottonwood St, Murray, UT, 84157, USA.|Division of Pulmonary and Critical Care Medicine, University of Utah, 30 N 1900 E, 701 Wintrobe, Salt Lake City, UT, 84132, USA.|Division of Pediatric Critical Care, Department of Pediatrics, University of Utah, 295 Chipeta Way, Salt Lake City, UT, 84108, USA.
authors.forename: Eliotte L
authors.initials: EL
authors.lastname: Hirshberg
authors.affiliation: Critical Care Echocardiography Service, Intermountain Medical Center, 5121 S Cottonwood St, Murray, UT, 84157, USA.|Division of Pulmonary and Critical Care Medicine, University of Utah, 30 N 1900 E, 701 Wintrobe, Salt Lake City, UT, 84132, USA.
authors.forename: Colin K
authors.initials: CK
authors.lastname: Grissom
authors.affiliation: Critical Care Echocardiography Service, Intermountain Medical Center, 5121 S Cottonwood St, Murray, UT, 84157, USA.|Division of Pulmonary and Critical Care Medicine, University of Utah, 30 N 1900 E, 701 Wintrobe, Salt Lake City, UT, 84132, USA.
authors.forename: Samuel M
authors.initials: SM
authors.lastname: Brown
keywords: Echocardiography; Preload; Septic cardiomyopathy; Strain; Tachycardia