Biomedical Engineering Reference
In-Depth Information
5.20 Calcification comparison between a prototype valve produced with an
optimized process and the Edwards PERIMOUNT
Õ
(CEP) valve. The calcium
++
content for each valve is reported (mg Ca
/mg dry tissue weight). Both valve
TM
types use Tween-80
as a calcification mitigation treatment; however, the
prototype process has been optimized to ensure effective treatment of every
tissue. By contrast, an individual PERIMOUNT Õ valve can occassionally
demonstrate moderate to significant calcification levels. (Figure reprinted with
permission fromArbor Surgical Technologies, Inc. (nowowned byMedtronic).
PERIMOUNT is a registered trademark of Edwards Lifesciences, Inc.)
reduce calcification in all samples, and all processes demonstrate a significant
standard deviation in mean calcium content within a group. This is evident in the
early studies reported by Jones et al. (1986), as well as more recent studies
reported by Flameng et al. (2006). Several recent processes have been described
which have been optimized to reduce calcification in all specimens, as deter-
mined by the rat subcutaneous implant model at 90 days (Cunanan et al., 2004,
2009). This was accomplished by approaching the problem using a chemical
engineering approach, which considers variability in the process. By the appli-
cation of variability-reducing methods such as design of experiments (DOE), the
critical inputs were identified and optimized for the desired output ± consistently
low calcium content after implantation. Demonstration of the success of this
approach has been reported in sheep (Flameng et al., 2008). As shown in Fig.
5.20, every valve implanted with the optimized process demonstrated very low
calcification levels, all below 3g calcium/mg dry tissue weight. In contrast, the
PERIMOUNT Õ valves tested in this study had calcium levels as high as 23.8g
calcium/mg dry tissue weight. As a patient may only receive one replacement
heart valve, it is an important concept to ensure that every heart valve has a
similarly low propensity to calcify.
￿ ￿ ￿ ￿ ￿
Search WWH ::




Custom Search