title: Systolic and diastolic unloading by mechanical support of the acute vs the chronic pressure overloaded right ventricle.
abstract: BACKGROUND
  Right ventricular (RV) mechanical support is well described in cases of sudden increase in RV afterload. In cases of chronic RV pressure overload (e.g., pulmonary arterial hypertension), it has rarely been described.
  
  
  METHODS
  The pulmonary artery was banded in 18 sheep. In the acute group (n = 9), we immediately implanted a Synergy Pocket Micro-Pump. Blood was withdrawn from the right atrium to the pulmonary artery. In the chronic group (n = 9), this pump was implanted 8 weeks after banding. Hemodynamics and pressure-volume loops were recorded before and 15 minutes after pump activation.
  
  
  RESULTS
  Low-flow RV mechanical support significantly improved arterial blood pressure in both groups, but cardiac output only in the acute group. Intrinsic RV contractility was not affected. The RV contribution to the total right-sided cardiac output was 54% ± 8 in the acute group vs 10% ± 13 in the chronic group (p < 1.10-5), indicating a more profound unloading in the latter. Diastolic unloading (reflected by decreases in central venous pressure, end-diastolic pressure and volume, and ventricular capacitance) was successful in both groups. Decreases in pressure-volume area and RV peak pressure reflected successful systolic unloading only in the chronic group.
  
  
  CONCLUSIONS
  Low-flow RV mechanical support improved arterial blood pressure in both conditions but caused a more profound unloading in the chronic group. Diastolic unloading was successful in both groups, but systolic unloading was successful only in the chronic group. The potential use of low-flow mechanical support for a chronic pressure overloaded right ventricle warrants further research to assess its long-term effects.
authors.affiliation: Department of Cardiac Surgery, University Hospitals Leuven, Leuven, Belgium; Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium. Electronic address: tom.verbelen@kuleuven.be.
authors.forename: Tom
authors.initials: T
authors.lastname: Verbelen
authors.affiliation: Division of Cardiology, Columbia University College of Physicians and Surgeons, New York, New York.
authors.forename: Daniel
authors.initials: D
authors.lastname: Burkhoff
authors.affiliation: Department of Cardiac Surgery, University Hospitals Leuven, Leuven, Belgium; Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium.
authors.forename: Keiichiro
authors.initials: K
authors.lastname: Kasama
authors.affiliation: Respiratory Division, University Hospitals Leuven, Leuven, Belgium; Department of Clinical and Experimental Medicine, University of Leuven, Leuven, Belgium.
authors.forename: Marion
authors.initials: M
authors.lastname: Delcroix
authors.affiliation: Department of Cardiac Surgery, University Hospitals Leuven, Leuven, Belgium; Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium.
authors.forename: Filip
authors.initials: F
authors.lastname: Rega
authors.affiliation: Department of Cardiac Surgery, University Hospitals Leuven, Leuven, Belgium; Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium.
authors.forename: Bart
authors.initials: B
authors.lastname: Meyns
mesh_terms: D000208:Acute Disease; D000818:Animals; D001243:Assisted Circulation; D002302:Cardiac Output / Q000502:physiology*; D002908:Chronic Disease; D003971:Diastole / Q000502:physiology*; D004195:Disease Models, Animal; D006325:Heart Atria / Q000503:physiopathology; D006976:Hypertension, Pulmonary / Q000503:physiopathology*; D012756:Sheep; D013599:Systole / Q000502:physiology*; D014655:Vascular Resistance / Q000502:physiology; D016278:Ventricular Function, Right / Q000502:physiology*
keywords: low-flow support; pulmonary hypertension; right ventricular assist device; right ventricular pressure overload