Overview Heart development 5 dilatations along primitive heart tube forms into adult heart structures dextral looping of the primitive heart aligns the heart chambers and structures septum and valves develop which allow for separation of the venous and arterial circulatory pathways heart begins beating during week 4 can be detected by transvaginal ultrasound by week 6 Embryonic structures Embryonic structure Adult structure Truncus Arteriosus Ascending aorta Pulmonary trunk Bulbus cordis Smooth part of left and right ventricle Primitive ventricle Trabeculated part of left and right ventricle Primitive atria Trabeculated part of left and right atrium Sinus venosus Coronary sinus Smooth part of right atrium Right common and right anterior cardinal vein SVC Truncus arteriosus neural crest cells migrate from hindbrain to aorticopulmonary (AP) trunk cells invade truncal and bulbar ridges the ridges then twist, spiral, and fuse to form the AP septum dividing the AP trunk into the ascending aorta and pulmonary trunk Persistent truncus arteriosus partial development of AP septum resulting in mixing of oxygenated and deoxygenated blood leading to cyanosis Transposition of great vessels (transposition of great arteries) ridges do not spiral as they develop resulting in two separate circulatory pathways aorta arises from the right ventricle pulmonary artery arises from the left ventricle blood never gets oxygenated which will result in neonatal death, unless there is a shunt between the two pathways VSD, patent foramen ovale, or PDA Tetralogy of Fallot skewed development of AP septum resulting in Pulmonary stenosis Right ventricular hypertrophy Overriding aorta VEntricular septal defect cyanosis but severity depends on degree of pulmonary stenosis Interventricular septum development Muscular ventricular septum forms from the floor of the primitive ventricle opening between muscular ventricular septum and fused AV cushions is called interventricular foramen AP septum then fuses with muscular ventricular septum to form the membranous interventricular septum Common ventricle muscular and membranous interventricular septum do not form Membranous septal defect failure of the membranous interventricular septum to form properly blood flows from left to right due to higher pressure in systemic circulatory system as a result pulmonary hypertension develops the lumen of pulmonary arteries and arterioles narrow due to proliferation of the tunica media and intima pulmonary resistance then becomes greater than systemic reversing the flow of blood across the opening the resulting condition is called Eisenmenger complex Interatrial septum development Septum primum grows downward from the superior part of the primitive atrium as the septum primum nears the atrioventricular cushions, new openings form at the center creating the foramen secundum foramen secundum allows for shunting of the blood from right to left Septum secundum grows downward and covers the foramen secundum leaving an opening inferiorly superior portion of septum primum degenerates inferior portion of septum primum and septum secundum form the foramen ovale foramen ovale remains open until birth at birth, right atrial pressure decreases and left aftrial pressures increases due to increased pulmonary blood flow into left atrium resting in the closure of the foramen ovale Patent foramen ovale foramen ovale does not close due to excessive resorption of septum primum, secundum, or both Interatrial septum needs to be penetrated to allow for access to the left side of the heart during procedures