HomeDepartmentsCardiovascular EngineeringValve Replacement & InterventionsFinished ProjectsConduit


Development of a Polyurethane Heart Valve Conduit

Fig. 1: Tetralogy of Fallot

A malformation of the right ventricular outflow tract (RVOT, connection between the right ventricle and the pulmonary artery) occurs in many congenital heart diseases (e.g. Fallot’s tetralogy, figure 1). This affects the total body circulation as well as the pulmonary circulation.

The continuity between the right ventricle and the pulmonary artery can be reconstructed among a surgical procedure.

 

 

None of the currently available procedures are ideal:

For some patients, the reconstruction of the RVOT is achieved by sewing a patch, in order to cover the distance between the right ventricle and the pulmonary artery.

For others, a valveless vascular graft (conduit) is used. However, due to the missing valve function, these methods result in a backflow from the pulmonary artery into the right ventricle (valve insufficiency). Consequently, a widening of the right ventricle is observed. Therefore, and especially when the pulmonary vascular resistance is high, vascular grafts with integrated valves are preferred.

Figure 2: Carpentier-Edwards Bioprothesis (Porcine)

Currently three kinds of valves are used: homografts (heart valve from deceased persons), so called biological valves (bovine/porcine) and mechanical heart valves. These valve substitutes are then integrated in the vascular graft (valved conduit, figure 2).

 

 

However, homografts and other biological valve present a considerable diminished durability (via calcification, shrinkage). Moreover, small diameter homografts specialised for infants and children are hardly available.

A novel approach is the use of bovine jugular vein valved conduits which are available in small diameters but often rapidly show narrowing and/ or dilation due to high pressure in the pulmonary artery.

Mechanical heart valves are known to have in adults a long durability, but demand a permanent anticoagulation therapy (risks of thromboemboli or bleeding) and are not available in small sizes. A common disadvantage to all those valve prostheses is their disability to grow.

Based on our positive experience with polymeric heart valves, we intend to integrate in a polyurethane vascular graft three valve leaflets (also made of polyurethane).

Summarizing, the goal of the project is the systemic construction and development of a valved conduit for the surgical reconstruction of the RVOT which:

  • posses optimised flow properties (unloading of the right ventricle, better durability, lower thrombogenicity)
  • doesn’t need a continuous anticoagulation treatment (prevention of thromboemboli, bleeding)
  • exhibits a higher durability (less surgeries)
  • is steadily stands an increase of the pulmonary valvular pressure (permanently intact valve function)
  • is easily available in small diameters (starting from 10mm) (optimal availability)
  • is applicable for a wide range of patients.

Methods

Development of a valved conduit made of biocompatible polycarbonaturethan, followed by in vitro and in vivo tests.

In order to achieve an optimal design, extensive constructive studies as well as numerical calculations are needed. Then, the results are validated through comparison with in vitro tests. The practical verification of the conduit's function is finally processed in a calf.

Kontakt

M.Sc. Dipl. -Ing. Yara Safi
Phone: +49 241 80 88764

E-mail

 

This project is sponsored by

and

Period of sponsorship: 2 years

Start: August 07

 

Theses and student work

Actual descriptions for theses and student work can be found Opens internal link in current windowhere.