Cardiac pacemaker discharge at about 40-60 beats per minute, and are called the "secondary pacemaker". Further down the electrical conducting system of the heart is the Bundle of His. The left and right branches of this bundle, and the Purkinje fibres, will also produce a spontaneous action potential at a rate of 30-40 beats per minute, so if the SA and AV node both fail to function, these cells can become pacemakers. It is important to realize that these cells will be initiating action potentials and contraction at a much lower rate than the primary or secondary pacemaker cells. The SA node
Cardiac neural crest cells secondary heart field cells into the cardiac outflow tract. FGF8 mouse mutants have a range of cardiac defects including underdeveloped arch arteries and transposition of the great arteries. GATA transcription factors, which are complex molecules that bind to the DNA sequence "GATA", play a critical role in cell lineage differentiation restriction during cardiac development. The primary function of GATA6 in cardiovascular development is to regulate the morphogenetic patterning of the outflow tract and aortic arch. When GATA6 is inactivated in CNCCs, various cardiovascular defects such as persistent truncus arteriorus and interrupted aortic arch may occur. This phenotype (anomaly) was also