Page 12 - Journal of Structural Heart Disease Volume 3, Issue 3

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Review Article
Melody valve because of the fracture rate, this is not essential for the Edwards TM valve as the frame is very robust with no fractures recorded on bench testing or in clinical trials. The stent material does not seem to matter with respect to metal to metal interaction that may cause corrosion or valve dysfunction although there are Chromium-Cobalt stents, such as the An- drastent XXL which are both robust and material compatible. The stents used must be able to dilate to large diameters with predetermined shortening to al- low for accurate placement and to cover the length of any narrowing. Although most of the time bare met- al stents are used, it is essential to have covered CP stents (NuMed) either for primary use if there is the possibility of conduit rupture or for a bailout situa- tion. If a longer covered stent is required above those available, these can be obtained from the manufac- turer as a special order up to 55mm in length. Stents that are commonly used for the RVOT include:
a) Andrastent (Andramed)
b) CP bare metal and covered (NuMed) c) Maxi LD (Ev3)
d) Palmaz (J & J)
These stents are often mounted on BiB, Cristal, or Z-Med balloons for deployment and delivered after RVOT interrogation to make sure that the stent or calci ed material will not compress the coronary ar- teries.
Venous closure
Venous access closure devices are not essential but some operators prefer to use these; however, simple manual compression or the use of a FemStop is an acceptable, alternative option. Devices that are commonly used include the Perclose/Proglide or the ProStar both from Abbott Vascular. An alternative is to form a gure-eight suture at the site of skin entry using thick silk on a large curved cutting needle; this invaginates the skin applying pressure to the femoral vein entry point and achieves hemostasis. The suture can be removed after six hours.
Patient Selection and Preparation
Patients are selected for pulmonary valve re- placement, according to accepted guidelines that include symptoms as well as supportive evidence
of significant stenosis, regurgitation, or a combina- tion of these; in other words, these patients would be equally candidates for surgery. Although some patients are suitable for either surgery or percu- taneous pulmonary valve replacement some may carry a higher risk or are considered not to be surgical candidates either because of cardiac or non-cardiac conditions ( e.g. Scoliosis, respiratory insufficiency, motor and/or developmental delay, psychological imbablance, amongst others). Some patients are asymptomatic but have objective evi- dence of significantly hemodynamic compromise. Those with symptoms often fall into NYHA class II or III.
Anatomic Situations
These include:
a) Truly native RVOT (usually stenosis due to dys-
plastic pulmonary valve or regurgitation fol-
lowing previous balloon valvuloplasty)
b) Trans-annular patch repair of native RVOT
c) Ventricle to pulmonary artery conduit (homo-
graft or xenograft)
Physiologic Factors
a) Severe RVOT obstruction with a peak gradient of greater than 50 mm Hg
b) Severe pulmonary regurgitation with right ven- tricular volume over load, a right ventricular end diastolic volume of greater than 150 ml/m2 on MRI, a regurgitant fraction of greater than 35% and a right ventricular ejection fraction of less than 40%
c) A combination of RVOT obstruction and regurgi- tation
d) Some patients may not have the above crite- ria but are nevertheless symptomatic with im- paired CPEX. Sometimes restrictive right ven- tricular physiology contributes to this clinical presentation.
Clinical Scenarios
a) Repaired Fallot’s tetralogy or pulmonary atresia with VSD
b) Repaired persistent arterial trunk
DeGiovanni, J.
Pulmonary Valve Replacement