title: Longitudinal shortening accounts for the majority of right ventricular contraction and improves after pulmonary vasodilator therapy in normal subjects and patients with pulmonary arterial hypertension.
abstract: BACKGROUND
  The right ventricle has a unique contraction pattern, with a greater portion of the shortening occurring in the longitudinal plane. However, the relative contributions of longitudinal and transverse shortening to overall right ventricular (RV) function have not been quantified. We sought to quantify the proportions of longitudinal and transverse shortening to RV function in normal subjects and in patients with pulmonary arterial hypertension (PAH) at baseline and following PAH-specific therapy.
  
  
  METHODS
  The normal cohort comprised 90 subjects with normal clinical echocardiograms, whereas the PAH cohort included 36 patients, of whom 25 had echocardiograms before and after initiation of PAH-specific therapy. Assessment of RV function included tricuspid annular plane systolic excursion, RV fractional area change (RVFAC), and relative change in RV area in longitudinal and transverse planes.
  
  
  RESULTS
  Longitudinal fractional area change (LFAC) accounted for the majority of total RVFAC (77% ± 14%) in normal subjects. Among patients with PAH, longitudinal shortening still represented the majority of RVFAC, even though it was less than in normal subjects (63% ± 18%, P < .0001). Following PAH therapy, overall RV function improved (RVFAC, 30% ± 13% to 36% ± 9%; P = .026), solely because of an increase in longitudinal area change. As a result, the proportion of longitudinal shortening increased (LFAC, 58% ± 18% to 69% ± 17%; P = .002), whereas transverse shortening fell (transverse fractional area change, 42% ± 18% vs 31% ± 17%; P = .002).
  
  
  CONCLUSIONS
  Longitudinal shortening accounts for the majority of RV contraction in normal subjects and patients with PAH, although less so in PAH. Improved RV function following pulmonary vasodilator therapy occurs solely from improvements in longitudinal contraction, suggesting that longitudinal shortening may represent the afterload-responsive element of RV functional recovery.
authors.affiliation: Division of Cardiology, Hospital of the University of Pennsylvania, Philadelphia, PA.
authors.forename: Suzanne B
authors.initials: SB
authors.lastname: Brown
authors.affiliation: Division of Cardiology, Hospital of the University of Pennsylvania, Philadelphia, PA.
authors.forename: Amresh
authors.initials: A
authors.lastname: Raina
authors.affiliation: Division of Cardiology, University of Colorado, Aurora, CO.
authors.forename: David
authors.initials: D
authors.lastname: Katz
authors.affiliation: Division of Cardiology, University of Arizona, Tucson, AZ.
authors.forename: Molly
authors.initials: M
authors.lastname: Szerlip
authors.affiliation: Division of Cardiology, Hospital of the University of Pennsylvania, Philadelphia, PA.
authors.forename: Susan E
authors.initials: SE
authors.lastname: Wiegers
authors.affiliation: Division of Cardiology, Hospital of the University of Pennsylvania, Philadelphia, PA. Electronic address: paul.forfia@uphs.upenn.edu.
authors.forename: Paul R
authors.initials: PR
authors.lastname: Forfia
mesh_terms: D000328:Adult; D004452:Echocardiography; D004562:Electrocardiography; D065627:Familial Primary Pulmonary Hypertension; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006976:Hypertension, Pulmonary / Q000175:diagnosis / Q000188:drug therapy / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction / Q000187:drug effects; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome; D014665:Vasodilator Agents / Q000627:therapeutic use*; D016278:Ventricular Function, Right / Q000187:drug effects*
chemical_list: D014665:Vasodilator Agents