title: Augmenting cardiac contractility hastens myocardial edema resolution after cardiopulmonary bypass and cardioplegic arrest.
abstract: Although myocardial edema is associated with cardiopulmonary bypass (CPB) and cardioplegic arrest (CPA), interventions to expedite edema removal have not been investigated. The primary mechanism for the removal of excess interstitial fluid in the heart is myocardial lymphatic drainage, but lymphatic function can be impaired by decreased contractility because of edema. The purpose of this study was to determine whether enhancing cardiac contractility would increase myocardial lymphatic function and hasten edema resolution after CPB. Sixteen dogs were subjected to CPB and 1 h of hypothermic CPA. After weaning from CPB, 10 dogs received an intravenous dobutamine infusion and 6 dogs received no inotropic support. We determined myocardial lymph driving pressure from the major cardiac lymphatic, myocardial water content by using microgravimetry, and the peak rate of left ventricular pressure increase (dP/dmax) by using micromanometry. Measurements were taken at baseline, during CPA, and 60 min after CPB. Compared with controls, dobutamine-treated dogs had an increased dP/dmax (P < 0.05), which was associated with higher lymph driving pressures (P < 0.05), resulting in lower myocardial water gain 1 h after CPB (P < 0.05). We conclude that the resolution of myocardial edema after CPB was hastened by dobutamine. Organized ventricular contraction and myocardial contractility seem to be important determinants of myocardial lymphatic function and myocardial edema removal. These findings suggest that the administration of inotropic drugs after CPB may hasten cardiac recovery.
  
  
  CONCLUSIONS
  Myocardial edema, which develops during cardiopulmonary bypass and cardioplegic arrest, contributes to cardiac dysfunction after heart surgery. This study demonstrated that enhancement of cardiac contractility by the administration of dobutamine after cardiopulmonary bypass and cardioplegic arrest was associated with increased myocardial lymphatic function and hastened edema resolution in dogs.
authors.affiliation: Department of Anesthesiology, University of Texas-Houston Medical School, 77030, USA. sallen@anes1.med.uth.tmc.edu
authors.forename: S J
authors.initials: SJ
authors.lastname: Allen
authors.forename: H J
authors.initials: HJ
authors.lastname: Geissler
authors.forename: K L
authors.initials: KL
authors.lastname: Davis
authors.forename: G R
authors.initials: GR
authors.lastname: Gogola
authors.forename: R D
authors.initials: RD
authors.lastname: Warters
authors.forename: E R
authors.initials: ER
authors.lastname: de Vivie
authors.forename: U
authors.initials: U
authors.lastname: Mehlhorn
mesh_terms: D000818:Animals; D002315:Cardiopulmonary Bypass / Q000009:adverse effects*; D002316:Cardiotonic Agents / Q000494:pharmacology*; D004280:Dobutamine / Q000494:pharmacology*; D004285:Dogs; D004489:Edema, Cardiac / Q000188:drug therapy* / Q000209:etiology* / Q000503:physiopathology; D005260:Female; D006324:Heart Arrest, Induced / Q000009:adverse effects*; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D013268:Stimulation, Chemical
chemical_list: D002316:Cardiotonic Agents; D004280:Dobutamine