Updated: 10/12/2022

Cardiac Development

Review Topic
Videos / Pods
embryonic structures
  • 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

interventricular septum2

  • 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

interatrial septum

  • 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 


Please rate topic.

Average 4.8 of 8 Ratings

Questions (6)
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK

(M1.EB.14.62) After receiving no prenatal care during her pregnancy, a 29-year-old woman gives birth to a full term male. Shortly after delivery the infant becomes cyanotic. Pulse oximetry is placed on upper and lower extremities. It reads <90% in all locations and oxygen saturation is unchanged with administration of 100% supplemental oxygen. An echocardiogram is performed and demonstrates the aorta lying anterior and to the right of the pulmonary artery. What typically occurs during fetal development that leads to the above congenital heart defect?

QID: 106454

Incomplete formation of septum secundum



Failure of the aorticopulmonary septum to spiral



Incomplete formation of ostium primum



Failure of interventricular septation



Failure of ductus arteriosus closure



M 1 E

Select Answer to see Preferred Response

Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK

(M1.EB.13.29) A patient in the neonatal intensive care unit develops severe cyanosis. Cardiac exam reveals a single loud S2 with a right ventricular heave. Echocardiography reveals an aorta lying anterior and right of the pulmonary artery. Which of the following processes failed during fetal development?

QID: 101923

Fusion of the membranous ventricular septum



Aorticopulmonary septum to spiral



Ectopic ductal tissue tightening



Reentry of viscera from yolk sac



Fusion of septum primum and septum secondum



M 1 E

Select Answer to see Preferred Response

Evidence (7)
Private Note