title: Biomechanical hearts: muscular blood pumps, performed in a 1-step operation, and trained under support of clenbuterol.
abstract: BACKGROUND
  As shown previously in goats, clenbuterol increased the power of electrically conditioned skeletal muscle ventricles (SMVs) of clinically relevant size (150 mL), which were constructed around a mock system. They pumped against a pressure of 60 to 70 mm Hg immediately during surgery and up to several months after, finally at >1 L/min. SMVs without clenbuterol administration failed. Thus, we expected that clenbuterol-supported SMVs might become integrated into the circulation by a 1-step operation instead of the 2-step procedure required up to now.
  
  
  RESULTS
  In adult Boer goats (n=5), latissimus dorsi muscle was wrapped around a polyurethane chamber of 150 mL that was connected to the descending aorta. This muscular flow-through pumping chamber containing a stabilizing inner layer (called a biomechanical heart [BMH]) was formed and immediately made to work against a systemic load with the support of clenbuterol (5x150 microg/wk). During surgery, the mean stroke volume of BMHs was 53.8+/-22.4 mL. One month after surgery, in peripheral arterial pressure, the mean diastolic (P(MD)) and minimal diastolic (P(min)) pressures of BMH-supported heart cycles differed significantly from unsupported ones (P(MD)=+2.9+/-1.1 mm Hg [P<0.04], P(min)=-2.4+/-0.9 mm Hg [P<0.04]). After BMH-supported heart contractions, the subsequent maximal rate of pressure generation, dP/dt(max), increased by 20.5+/-8.1% (P<0.02). One BMH, catheterized 132 days after surgery, shifted a volume of 34.8 mL per beat and 1.4 L/min with a latissimus dorsi muscle of 330 g. Depending on duration of training, the percentage of myosin heavy chain type 1 ranged between 31% and 100%.
  
  
  CONCLUSIONS
  Under support of clenbuterol, BMHs of a clinically relevant size can be trained effectively in the systemic circulation after a 1-step operation and offer the prospect of a sufficient volume shift and probably unloading of the left ventricle.
authors.affiliation: Clinic of Cardiac Surgery, Institutes of Anesthesiology, Clinic of Cardiology Medical University of Lübeck, Lübeck, Germany. guldner@medinf.mu-luebeck.de
authors.forename: N W
authors.initials: NW
authors.lastname: Guldner
authors.forename: P
authors.initials: P
authors.lastname: Klapproth
authors.forename: M
authors.initials: M
authors.lastname: Grossherr
authors.forename: A
authors.initials: A
authors.lastname: Brügge
authors.forename: A
authors.initials: A
authors.lastname: Sheikhzadeh
authors.forename: R
authors.initials: R
authors.lastname: Tölg
authors.forename: E
authors.initials: E
authors.lastname: Rumpel
authors.forename: R
authors.initials: R
authors.lastname: Noel
authors.forename: H H
authors.initials: HH
authors.lastname: Sievers
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D001794:Blood Pressure / Q000187:drug effects; D002976:Clenbuterol / Q000494:pharmacology; D006041:Goats; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D018482:Muscle, Skeletal / Q000737:chemistry / Q000187:drug effects; D009200:Myocardial Contraction / Q000187:drug effects; D018995:Myosin Heavy Chains / Q000187:drug effects / Q000378:metabolism; D019739:Skeletal Muscle Ventricle / Q000098:blood supply / Q000502:physiology; D013318:Stroke Volume / Q000187:drug effects
chemical_list: D018995:Myosin Heavy Chains; D002976:Clenbuterol