title: The combined role of sinuses of Valsalva and flow pulsatility improves energy loss of the aortic valve.
abstract: OBJECTIVE
  Normal aortic valve opening and closing movement is a complex mechanism mainly regulated by the blood flow characteristics and the cyclic modifications of the aortic root. Our previous in vitro observations demonstrated that the presence of the Valsalva sinuses, independently from root compliance, is important in reducing systolic pressure drop across the aortic valve. This in vitro study was designed to ascertain if this effect is dependent on the flow characteristics.
  
  
  METHODS
  Stentless 21, 23 and 25 mm aortic prostheses were sutured inside Dacron graft with and without sinuses. Hydrodynamic performance of the root models was investigated in steady-state (continuous) and unsteady-state (pulsatile) flow regimes. Aortic transvalvular pressure drop and effective orifice area (EOA) were evaluated.
  
  
  RESULTS
  The continuous flow analysis revealed that no marked differences in pressure drop characterized the two root configurations at flow regimes lower than 15 l/min, independently of valve size. Conversely, at higher flow regimes (up to 30 l/min) a relatively low pressure drop continued to characterize grafts with sinuses, whereas marked increments in pressure drop were measured in straight grafts, especially in the smaller size (77.05 ± 4.58 vs 23.80 ± 2.44 mmHg; 18.40 ± 1.31 vs 7.66 ± 0.37 mmHg and 29.54 ± 0.17 vs 7.12 ± 0.07 mmHg, for 21, 23 and 25 mm valve, respectively). Under pulsatile conditions, the presence of sinuses clearly confirmed lower pressure drops also more evident in the smaller valve sizes (53.89 ± 1.06 vs 11.6 ± 0.24 mmHg at 7 l/min for 21 mm valve). EOA values were always lower in the absence of sinuses. In continuous flow regimes, at 30 l/min EOA of 25 mm valve size was 3.67 ± 0.02 cm(2) in the Valsalva model versus 1.79 ± 0.01 cm(2) for the Straight model. In pulsatile tests, at 7 l/min a 25-valve size demonstrated an EOA of 5.47 ± 0.60 in the Valsalva model versus 2.50 ± 0.02 cm(2) in the Straight model.
  
  
  CONCLUSIONS
  These findings (i) confirm the hypothesis that the sinuses of Valsalva play a key role in optimizing the aortic haemodynamics during systole, minimizing energy losses; (ii) suggest that the sinuses of Valsalva are needed because of the complex nature of blood flow during ejection.
authors.affiliation: Division of Cardiac Surgery, European Hospital, Rome, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Salica
authors.affiliation: Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Pisani
authors.affiliation: Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy.
authors.forename: Umberto
authors.initials: U
authors.lastname: Morbiducci
authors.affiliation: Division of Cardiac Surgery, European Hospital, Rome, Italy.
authors.forename: Raffaele
authors.initials: R
authors.lastname: Scaffa
authors.affiliation: Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy.
authors.forename: Diana
authors.initials: D
authors.lastname: Massai
authors.affiliation: Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Audenino
authors.affiliation: Division of Cardiac Surgery, European Hospital, Rome, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Weltert
authors.affiliation: Division of Cardiac Surgery, European Hospital, Rome, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Guerrieri Wolf
authors.affiliation: Division of Cardiac Surgery, European Hospital, Rome, Italy depauli@tin.it.
authors.forename: Ruggero
authors.initials: R
authors.lastname: De Paulis
mesh_terms: D001021:Aortic Valve / Q000502:physiology* / Q000601:surgery; D006350:Heart Valve Prosthesis; D006801:Humans; D008955:Models, Cardiovascular; D011673:Pulsatile Flow / Q000502:physiology*; D012850:Sinus of Valsalva / Q000502:physiology*; D013599:Systole
keywords: Aortic valve; Dacron graft; Haemodynamics; Sinuses of Valsalva; Valve-sparing