Limitations
There are several limitations to our study beyond those noted above.
First, evaluation was done on a limited number of hearts. Thus,
consistency in results across larger sample sizes needs to be evaluated.
Second, these studies reflected acute evaluations of changes in
conduction both post-ablation and post-injection. It is possible that
lesion maturation may occur over a longer period of time, resulting in
dynamic shifts in cardiac activation that may not have been reflected in
the acute state. Third, as stated previously, we could not inject a
predictable amount of hydrogel each time due to materials properties not
permitting appropriate in-tissue retention. Thus, we could not determine
a threshold amount of material that would need to be injected to
facilitate some change in conduction. In addition, the approach to the
testing and mapping (ex vivo perfused hearts and epicardial only
mapping) may not necessarily extend to in vivo examples, and, thus,
before further conclusions can be made, in vivo acute and chronic
studies will be needed. Finally, we could not evaluate immunogenicity or
potential for chronic maintenance of the perceived conduction changes
due to the acute and ex vivo nature of the study.
Conclusion Our study shows that novel injectable conductive hydrogel can enhance
myocardial conduction through regions of tissue injury. Future studies
will need to focus on optimizing rheological, electrical conductivity,
and in-situ gel formation properties of the conductive hydrogel such
that it can be predictably retained within tissue while maintaining
conductive properties. In addition, it will be important to improve
understanding of the effect on local conduction not just epicardially
but transmurally. Finally, establishing both long-term durability of
activation normalization and biocompatibility will be key.