title: [Circulatory assist device in counterpulsation].
abstract: OBJECTIVE
  To test a circulatory assist device (CAD) developed in the University of São Paulo. Heart Institute, Bioengineering Division. It is a valveless chamber working through the counterpulsation principle, aiming at assistance to temporary the left ventricle.
  
  
  METHODS
  The CAD consists of a rigid polycarbonate shell, which houses in its interior a polyurethane bag with a maximum volume of 110 cm3, driven alternately by pressure and vacuum from an external electropneumatic device synchronized with the ECG. The device worked for 300 hours in a test bench simulating the cardiovascular system in order to verify its resistance to wear and fatigue. The CAD was implanted near the aortic root of five dogs, in whom cardiac failure was induced through the use of propranolol and plasma expanders. The CAD was driven for five periods of 2 minutes separated by pauses of equal duration. The hemodynamic parameters were measured during the mentioned periods.
  
  
  RESULTS
  "In vitro" testing resulted in no wear or fatigue. No leakage was observed. In the "in vivo" testing the averages obtained during the on and off periods of the device showed for the on periods; a) lowering of the systolic pressures of both the aorta (17.5%) and the left ventricle (LV) 15.1%), lowering of the final diastolic pressure of the LV (15.4%) and lowering of the diastolic pressure of the aorta (27.4%); b) increase in cardiac output (45.5%); c) increase of the endocardial viability ratio by 37.5%.
  
  
  CONCLUSIONS
  The tested device represents a therapeutic option in cases of acute left ventricle failure, since with it an improved cardiac performance was measured and an increased coronary perfusion can be presumed.
authors.affiliation: Instituto do Coração do Hospital das Clínicas-FMUSP.
authors.forename: A A
authors.initials: AA
authors.lastname: Leirner
authors.forename: E
authors.initials: E
authors.lastname: Marques
authors.forename: M P
authors.initials: MP
authors.lastname: Ribeiro
authors.forename: S G
authors.initials: SG
authors.lastname: Lage
authors.forename: A D
authors.initials: AD
authors.lastname: Jatene
mesh_terms: D000818:Animals; D015908:Counterpulsation; D004285:Dogs; D006333:Heart Failure / Q000139:chemically induced / Q000628:therapy; D006353:Heart-Assist Devices; D006439:Hemodynamics; D008297:Male; D010952:Plasma Substitutes / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology
chemical_list: D010952:Plasma Substitutes; D011433:Propranolol
vernacular_title: Dispositivo de assistencia circulatoria em contrapulsacao.