title: Heart Rate Dependence of the Pulmonary Resistance x Compliance (RC) Time and Impact on Right Ventricular Load.
abstract: BACKGROUND
  The effect of heart rate (HR) and body surface area (BSA) on pulmonary RC time and right ventricular (RV) load is unknown.
  
  
  METHODS
  To determine the association of HR and BSA with the pulmonary RC time and measures of RV load, we studied three large patient cohorts including subjects with 1) known or suspected pulmonary arterial hypertension (PAH) (n = 1008), 2) pulmonary hypertension due to left heart disease (n = 468), and 3) end-stage heart failure with reduced ejection fraction (n = 150). To corroborate these associations on an individual patient level, we performed an additional analysis using high-fidelity catheters in 22 patients with PAH undergoing right atrial pacing.
  
  
  RESULTS
  A faster HR inversely correlated with RC time (p<0.01 for all), suggesting augmented RV pulsatile loading. Lower BSA directly correlated with RC time (p<0.05) although the magnitude of this effect was smaller than for HR. With incremental atrial pacing, cardiac output increased and total pulmonary resistance (TPR) fell. However, effective arterial elastance, its mean resistive component (TPR/heart period; 0.60±0.27 vs. 0.79±0.45;p = 0.048), and its pulsatile component (0.27±0.18 vs 0.39±0.28;p = 0.03) all increased at faster HR.
  
  
  CONCLUSIONS
  Heart rate and BSA are associated with pulmonary RC time. As heart rate increases, the pulsatile and total load on the RV also increase. This relationship supports a hemodynamic mechanism for adverse effects of tachycardia on the RV.
authors.affiliation: Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America.
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Metkus
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Mullin
authors.affiliation: Division of Cardiovascular Medicine, University of Pennsylvania, Philadelphia, PA, United States of America.
authors.forename: E Wilson
authors.initials: EW
authors.lastname: Grandin
authors.affiliation: Division of Cardiovascular Medicine, University of Pennsylvania, Philadelphia, PA, United States of America.
authors.forename: J Eduardo
authors.initials: JE
authors.lastname: Rame
authors.affiliation: Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America.
authors.forename: Emmanouil
authors.initials: E
authors.lastname: Tampakakis
authors.affiliation: Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America.
authors.forename: Steven
authors.initials: S
authors.lastname: Hsu
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America.
authors.forename: Todd M
authors.initials: TM
authors.lastname: Kolb
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America.
authors.forename: Rachel
authors.initials: R
authors.lastname: Damico
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America.
authors.forename: Paul M
authors.initials: PM
authors.lastname: Hassoun
authors.affiliation: Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America.
authors.forename: David A
authors.initials: DA
authors.lastname: Kass
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America.
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Mathai
authors.affiliation: Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America.
authors.forename: Ryan J
authors.identifier: http://orcid.org/0000-0001-9045-7722
authors.initials: RJ
authors.lastname: Tedford
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006334:Heart Function Tests; D006339:Heart Rate; D006352:Heart Ventricles; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D011651:Pulmonary Artery / Q000503:physiopathology*; D012189:Retrospective Studies; D014655:Vascular Resistance; D018497:Ventricular Dysfunction, Right; D016276:Ventricular Function