Updated: 7/19/2018

Cardiac Development

Review Topic
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
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 resoprtion of septum primum, secundum, or both



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Questions (6)
Lab Values
Blood, Plasma, Serum Reference Range
ALT 8-20 U/L
Amylase, serum 25-125 U/L
AST 8-20 U/L
Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL
Calcium, serum (Ca2+) 8.4-10.2 mg/dL
Cholesterol, serum Rec: < 200 mg/dL
Cortisol, serum 0800 h: 5-23 μg/dL //1600 h:
3-15 μg/dL
2000 h: ≤ 50% of 0800 h
Creatine kinase, serum Male: 25-90 U/L
Female: 10-70 U/L
Creatinine, serum 0.6-1.2 mg/dL
Electrolytes, serum  
Sodium (Na+) 136-145 mEq/L
Chloride (Cl-) 95-105 mEq/L
Potassium (K+) 3.5-5.0 mEq/L
Bicarbonate (HCO3-) 22-28 mEq/L
Magnesium (Mg2+) 1.5-2.0 mEq/L
Estriol, total, serum (in pregnancy)  
24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL
28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL
Ferritin, serum Male: 15-200 ng/mL
Female: 12-150 ng/mL
Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL
Female: premenopause: 4-30 mIU/mL
midcycle peak: 10-90 mIU/mL
postmenopause: 40-250
pH 7.35-7.45
PCO2 33-45 mmHg
PO2 75-105 mmHg
Glucose, serum Fasting: 70-110 mg/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative stimuli: > 7ng/mL
Immunoglobulins, serum  
IgA 76-390 mg/dL
IgE 0-380 IU/mL
IgG 650-1500 mg/dL
IgM 40-345 mg/dL
Iron 50-170 μg/dL
Lactate dehydrogenase, serum 45-90 U/L
Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL
Female: follicular phase: 5-30 mIU/mL
midcycle: 75-150 mIU/mL
postmenopause 30-200 mIU/mL
Osmolality, serum 275-295 mOsmol/kd H2O
Parathyroid hormone, serume, N-terminal 230-630 pg/mL
Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L
Phosphorus (inorganic), serum 3.0-4.5 mg/dL
Prolactin, serum (hPRL) < 20 ng/mL
Proteins, serum  
Total (recumbent) 6.0-7.8 g/dL
Albumin 3.5-5.5 g/dL
Globulin 2.3-3.5 g/dL
Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL
Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h
Thyroxine (T4), serum 5-12 μg/dL
Triglycerides, serum 35-160 mg/dL
Triiodothyronine (T3), serum (RIA) 115-190 ng/dL
Triiodothyronine (T3) resin uptake 25%-35%
Urea nitrogen, serum 7-18 mg/dL
Uric acid, serum 3.0-8.2 mg/dL
Hematologic Reference Range
Bleeding time 2-7 minutes
Erythrocyte count Male: 4.3-5.9 million/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 12.0-16.0 g/dL
Hemoglobin, plasma 1-4 mg/dL
Leukocyte count and differential  
Leukocyte count 4,500-11,000/mm3
Segmented neutrophils 54%-62%
Bands 3%-5%
Eosinophils 1%-3%
Basophils 0%-0.75%
Lymphocytes 25%-33%
Monocytes 3%-7%
Mean corpuscular hemoglobin 25.4-34.6 pg/cell
Mean corpuscular hemoglobin concentration 31%-36% Hb/cell
Mean corpuscular volume 80-100 μm3
Partial thromboplastin time (activated) 25-40 seconds
Platelet count 150,000-400,000/mm3
Prothrombin time 11-15 seconds
Reticulocyte count 0.5%-1.5% of red cells
Thrombin time < 2 seconds deviation from control
Plasma Male: 25-43 mL/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 19-31 mL/kg
Cerebrospinal Fluid Reference Range
Cell count 0-5/mm3
Chloride 118-132 mEq/L
Gamma globulin 3%-12% total proteins
Glucose 40-70 mg/dL
Pressure 70-180 mm H2O
Proteins, total < 40 mg/dL
Sweat Reference Range
Chloride 0-35 mmol/L
Calcium 100-300 mg/24 h
Chloride Varies with intake
Creatinine clearance Male: 97-137 mL/min
Female: 88-128 mL/min
Estriol, total (in pregnancy)  
30 wks 6-18 mg/24 h
35 wks 9-28 mg/24 h
40 wks 13-42 mg/24 h
17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 6-15 mg/24 h
Osmolality 50-1400 mOsmol/kg H2O
Oxalate 8-40 μg/mL
Potassium Varies with diet
Proteins, total < 150 mg/24 h
Sodium Varies with diet
Uric acid Varies with diet
Body Mass Index (BMI) Adult: 19-25 kg/m2

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(M1.EB.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? Review Topic

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




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(M1.EB.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? Review Topic

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




Select Answer to see Preferred Response

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