title: Dobutamine stress echocardiography predicts myocardial improvement in patients supported by left ventricular assist devices (LVADs): hemodynamic and histologic evidence of improvement before LVAD explantation.
abstract: BACKGROUND
  Cardiac function may improve in patients with end-stage heart failure who receive long-term support (>30 days) with left ventricular assist devices (LVADs). Dobutamine stress echocardiography (DSE) has been used to quantitate myocardial recovery in patients with heart failure supported with LVADs. By recording the hemodynamic response with the use of DSE, we evaluated and applied the resulting data to patients receiving LVAD support.
  
  
  RESULTS
  The study population included 16 patients who underwent LVAD implantation, regained functional capacity on full LVAD support, and tolerated decreased mechanical support with no worsening of dyspnea or fatigue. All 16 patients underwent dobutamine stress with increasing doses of dobutamine (from 5 to 40 mcg/kg/min). Hemodynamics and 2-dimensional (2-D) echocardiography was performed at each dose level. In addition, paired myocardial samples were obtained and analyzed histologically to determine myocyte size and collagen content. Dobutamine stress separated the study population into 2 groups: those who had favorable responses to dobutamine (9/16) and those who had unfavorable responses (i.e., experienced hemodynamic deterioration; 7/16). Favorable dobutamine responses were characterized by improved cardiac index, improved force-frequency relationship in the left ventricle (dP/dt), improved left ventricular ejection fraction, and decreased left ventricular end-diastolic dimension. All 9 favorable responders underwent LVAD explantation, and 6 survived for more than 12 months. In all patients studied, LVAD support resulted in decreased myocyte size (n = 14, 33.9 +/- 0.9 microm before vs 16.6 +/- 0.8 microm after support, p = 0.0001; normal, 5-15 microm) but resulted in no consistent changes in collagen content.
  
  
  CONCLUSIONS
  Dobutamine stress echocardiography with hemodynamic assessment may be a useful tool in assessing physiologic improvement in myocardial function of patients with end-stage heart failure who receive LVAD support. It may help predict which patients can tolerate LVAD removal. Prospective analysis of cardiac function is now warranted to better define myocardial recovery in patients supported with LVADs.
authors.affiliation: Department of Cardiopulmonary Transplantation at the Texas Heart Institute at St Luke's Episcopal Hospital, Houston, Texas 77225-0345, USA.
authors.forename: Tehreen
authors.initials: T
authors.lastname: Khan
authors.forename: Reynolds M
authors.initials: RM
authors.lastname: Delgado
authors.forename: Brano
authors.initials: B
authors.lastname: Radovancevic
authors.forename: Guillermo
authors.initials: G
authors.lastname: Torre-Amione
authors.forename: Jackie
authors.initials: J
authors.lastname: Abrams
authors.forename: Kathy
authors.initials: K
authors.lastname: Miller
authors.forename: Timothy
authors.initials: T
authors.lastname: Myers
authors.forename: Kristen
authors.initials: K
authors.lastname: Okerberg
authors.forename: Sonny J
authors.initials: SJ
authors.lastname: Stetson
authors.forename: Igor
authors.initials: I
authors.lastname: Gregoric
authors.forename: Antonita
authors.initials: A
authors.lastname: Hernandez
authors.forename: O H
authors.initials: OH
authors.lastname: Frazier
mesh_terms: D000328:Adult; D002311:Cardiomyopathy, Dilated / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000628:therapy*; D016022:Case-Control Studies; D020878:Device Removal; D025401:Echocardiography, Stress; D005260:Female; D006353:Heart-Assist Devices; D006439:Hemodynamics; D006801:Humans; D008297:Male; D009200:Myocardial Contraction; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000628:therapy*; D009206:Myocardium / Q000473:pathology; D032383:Myocytes, Cardiac / Q000473:pathology