Examining Developmental Changes in Heart Contractions of Children With Congenital Heart Defects

Congenital heart defects are abnormalities or problems with the structure of the heart that
are present at birth. Examples of congenital heart defects include hypoplastic left heart
syndrome, which is a condition that occurs when the left side of the heart does not develop
completely, and tetralogy of Fallot, which is a condition that involves four specific types
of structural defects within the heart. Many advances have been made in recent years in the
field of pediatric heart surgery, and children who are born with congenital heart defects
are now able to undergo heart surgery as infants to repair the defects. However, very little
is known about the differences between how an infant's heart functions and how an adult's
heart functions. Thus, most of the therapies that are used to treat children with heart
defects were originally developed for adults and may not be the best option for infants and
young children. The purpose of this study is to gain a better understanding of how the heart
changes during a child's first year of life, from being a newborn less than 1 week old to
being an infant 3 to 12 months old.

During surgical repair of congenital heart defects, tissue from the ventricular structures
of the heart is sometimes removed as part of the surgery. In this study, researchers will
examine ventricular tissue removed during the surgical procedures of newborns with
hypoplastic left heart syndrome and infants with tetralogy of Fallot. Study researchers will
compare the newborn and infant tissue samples in terms of their differences in
excitation-contraction coupling, also referred to as contraction response.
Excitation-contraction coupling in the heart is the process wherein electrical activity of
the heart is translated into contraction of the heart muscle, which then results in pumping
of the blood out to the body. Study researchers will also examine how calcium, which is
required for heart contraction, flows in and out of heart cells to determine whether the
process differs among newborns and infants. Acquiring data on both excitation-contraction
coupling and the role of calcium is important because increasing the strength of heart
contractions is a key component of treatment options for children with congenital heart
defects.

Inclusion Criteria:

- Newborns less than 1 week of age with hypoplastic left heart syndrome

- Infants between 3 to 12 months of age with tetralogy of Fallot

- Requires removal of ventricular tissue during surgery as part of the repair for a
congenital heart defect

Exclusion Criteria

- Children > 12 months of age