title: The efficacy of the high volume counterpulsation technique at very low levels of aortic pressure.
abstract: BACKGROUND
  The objective of the present study was to identify the hemodynamic variables, that preclude the effectiveness of the counterpulsation technique.
  
  
  METHODS
  In order to achieve high counterpulsation volume two devices were used simultaneously. The para-aortic counterpulsation device pumping 60-70 ml was implanted on the ascending aorta, and the intra-aortic balloon (20 ml) was placed in the descending aorta of 14 dogs with severe cardiogenic shock. Both devices were synchronized to provide aortic diastolic augmentation. The mechanical assistance provided by these devices was considered adequate when the mean aortic pressure during the supportive period was at least 50 mmHg, a pressure compatible with life.
  
  
  RESULTS
  The mechanical assistance provided by the two devices was adequate in none (0%) of the cases with a systolic aortic pressure below 30 mmHg (Group I), in 71% of the cases with a systolic aortic pressure between 30-56 mmHg (Group II), and in 100% of the cases with a systolic aortic pressure above 56 mmHg (Group III). In group II the left ventricular end-diastolic pressure was higher in the cases responding adequately to mechanical assistance (Subgroup IIa) than in the ones where no adequate response was obtained (Subgroup IIb).
  
  
  CONCLUSIONS
  The very low levels of the systolic aortic pressure was the most important factor precluding the adequate effectiveness of the counterpulsation technique.
authors.affiliation: Department of Clinical Therapeutics, Alexandra Hospital, University of Athens, School of Medicine, Greece.
authors.forename: C E
authors.initials: CE
authors.lastname: Charitos
authors.forename: J N
authors.initials: JN
authors.lastname: Nanas
authors.forename: D A
authors.initials: DA
authors.lastname: Kontoyiannis
authors.forename: S N
authors.initials: SN
authors.lastname: Nanas
authors.forename: G Z
authors.initials: GZ
authors.lastname: Stamatopoulos
authors.forename: A C
authors.initials: AC
authors.lastname: Rapti
authors.forename: S F
authors.initials: SF
authors.lastname: Stamatelopoulos
authors.forename: S D
authors.initials: SD
authors.lastname: Moulopoulos
mesh_terms: D000818:Animals; D001011:Aorta / Q000503:physiopathology*; D001794:Blood Pressure; D004195:Disease Models, Animal; D004285:Dogs; D007423:Intra-Aortic Balloon Pumping / Q000379:methods*; D009200:Myocardial Contraction; D012770:Shock, Cardiogenic / Q000503:physiopathology* / Q000628:therapy; D016896:Treatment Outcome