Hydrodynamic ex vivo analysis of valve-sparing techniques: assessment and comparison

Abstract

Objectives: Valve-sparing procedures are surgical techniques allowing to restore adequate function of the native aortic valve by replacing the dysfunctional ascending aorta with a prosthetic conduit. A number of techniques are currently used, such as Yacoub's remodelling and David's reimplantation, based on a regular straight conduit. More recently, the De Paulis proposed the use of bulging conduits to reconstruct the shape of the Valsalva sinuses. This work investigates the impact of the valve-sparing technique on the aortic valve function.

Methods: The performance of 3 porcine aortic roots (Medtronic Freestyle™) was assessed in a cardiovascular pulse duplicator before and after performing 3 alternative valve-sparing procedures: David's reimplantation, Yacoub's remodelling and De Paulis' reimplantation.

Results: The porcine aortic roots, representative of the healthy native configuration, were characterized by the highest efficiency, with a mean energetic dissipation under normal operating conditions of 26 mJ. David's and Yacoub's techniques resulted in significantly lower performance (with mean energetic loss of about 70 mJ for both cases). The De Paulis' procedure exhibited intermediate behaviour, with superior systolic performance and valve dynamics similar to the native case, and a mean energetic loss of 38 mJ.

Conclusions: The dynamics and performance after valve-sparing strongly depend on the adopted technique, with the use of conduits replicating the presence of Valsalva sinuses restoring more physiological conditions.

Keywords: Ex vivo analysis; Aortic root prosthesis; Hydrodynamic performance; Valsalva sinuses; Valve-sparing implants.

Figure 1:

Freestyle prosthesis. Sagittal, inflow and outflow views.

Figure 2:

David implant steps: (a) equipment, (b) native valve cutting, (c) valve preparation, (d) graft suturing, final implant, (e) transversal and (f) sagittal views.

Figure 3:

Healthy native prosthesis and valve-sparing implants, David, Yacoub and De Paulis, set into resin support.

Figure 4:

Implant performance parameter diagram of: (a–c) $\Delta P$; (d–f) EOA; (g–i) CRV; (l–n) $E_{\mathrm{lossF}}+E_{\mathrm{lossC}}$. Each diagram reports mean performances value in 10 cycles. The standard deviation is reported as error bars.

Figure 5:

Mean $E_{\mathrm{lossC}}$ and $E_{\mathrm{lossF}}\mathrm{ }$for each kind of implant.

Figure 6:

HFR images corresponding to the POA maximum value.