Embryo Clinical Notes

Question 1

Laryngeal atresia

Answer 1

• present with asphyxia at time of birth
• obstruction of upper fetal airway
• results from failure of recanalization (no apoptosis during 10th week)

Question 2

Laryngeal webs

Answer 2

• incomplete atresia
• tissue between vocal folds
• usually present in infancy with respiratory distress and unusual cry or stridor

Question 3

Laryngomalacia

Answer 3

• also called congenital laryngeal stridor, refers to collapse of the supraglottic structures during inspiration (open during exhalation, collapse on inspiration)
• most common congenital anomaly of the larynx

Question 4

TE fistula (2 types)

Answer 4

1. Esophageal atresia (blind end esophagus, most common - 84% of cases)
2. Tracheoesophageal fistula (abnormal passage between trachea and esophagus

Both are due to failure of foregut endoderm to proliferate fast enough, so TE fold doesn’t fuse during the 5th week. Will have a colicky baby that spits up during feeding

Question 5

Respiratory distress syndrome

Answer 5

Aka Hyaline membrane disease

• tachypnea, cyanosis, nasal flaring and grunting
• subcostal, intercostal or supraclavicular retractions to compensate breathing
• lungs are under inflated, looks like fuzzy ground glass on Xray because alveoli contain fluid that looks like glass membrane
• caused by lack (or irreversible damage) of Type 2 pneumocytes , leading to a lack of surfactant

Question 6

Congenital diaphragmatic hernia

Answer 6

• Aka foramen of Brochdalek
• intestines in the thoracic cavity!
• barrel shaped chest, scaphoid appearing abdomen
• absence of breath sounds on the left side, heartbeat displaced to the right due to mediastinal shift
• caused by failure of septum transversum and plueroperitoneal membrane to fuse during week 6

Question 7

Polyhydramnios

Answer 7

• can lead to TE fisula -> infant presents with coughing, gagging, cyanosis, vomiting, voluminous oral secretions and possible respiratory distress
• prevents TE folds from fusing during the 5th week

Question 8

Congenital lung cysts

Answer 8

• cysts filled with fluid or air
• thought to result from a disturbance in bronchial development during late fetal life
• has a honeycomb appearance on Xray

Question 9

Patent ductus arteriosus

Answer 9

• Acyanotic defect, L->R (high pressure blood in aorta goes into pulmonary trunk), presents as continuous machinery murmur, can destroy capillary beds in lungs
• poor eating, sweating with crying or eating, rapid HR, easily tires, tachypnea
• PDA doesnt close due to low oxygen content and circulating PGE2, which is produced in part by the placenta and is mediated by its COX-2 isoform
• treatment: COX-2 inhibitors, ibuprofen or indomethacin

Question 10

Atrial septal defect

Answer 10

• Acyanotic defect, L->R, more common in females
• Ostium secundum (high atrial septal defect 90% of cases): hole in atrial septum caused by either excessive absorption of septum primum causing overly large foramen secundum, OR inadequate development of septum secundum
• Ostium primum (low atrial septal defect): septum primum does not fuse with endocardial cushion, associated with mitral valve cleft
• Probe patent formen ovale: present in 25% of people, incomplete adhesion between foramen ovale and septum primum after birth

Question 11

Ventricular septal defects

Answer 11

• Acyanotic (L->R) more common in males
• harsh or blowing systolic murmur, best heard at the left mid to lower sternal border or left 3rd-4th intercostal space
• caused by failure of neural crest cells, no bulbar ridges fusing with endocardial cushion

Question 12

AV septal defects

Answer 12

• Acyanotic (L->R), caused by failure of endocardial cushion to fuse
  -Complete: primum ASD that is contiguous with VSD and common AV valve (both ventricular and atrial septal defects, with abnormal valve leaflets)
• Partial: primum ASD, a single AV valve annulus with 2 separate valve orifices, atrial septal defect and abnormal valve leaflets (anterior cusp of bicusped valve is typically cleft)
  NOTE: 20% of persons with Downs syndrome affected!

Question 13

“Corrected” transposition of great vessels

Answer 13

• Acyanotic (L->R)

- caused by neural crest defect (improper septation of outflow tract) or reverse rotation of heart

Question 14

Complete transposition of great vessels

Answer 14

• Cyanotic (R->L)
• great vessels form wrong ventricles
• septal defects
• persistent ductus arteriosis
• neural crest defect: problem with 180 degree spiraling

Question 15

Double outlet right ventricle

Answer 15

• Cyanotic (R->L)
• great vessels form “right ventricle”
• ventricular septal defect in most cases
• neural crest defect: abnormal migration of bulbar ridges during septation, muscular portion of interventricular septum misaligned

Question 16

Truncus arteriosus

Answer 16

• Cyanotic (R->L), single great vessel

- neural crest interventricular defect: absence of bulbar ridges and truncal ridges to form/align properly

Question 17

Tetralogy of Fallot

Answer 17

• Cyanotic (R->L), very serious and very common
• pulmonary stenosis
• IV septal defect
• over-riding aorta
• right ventricular hypertrophy
• neural crest defect: abnormal septation of outflow tract

Question 18

Critical pulmonary stenosis

Answer 18

• Cyanotic (R->L) decreases pulmonary blood flow

- cusps of pulmonary valves are fused or thickened

Question 19

Critical aortic stenosis

Answer 19

• Cyanotic (R->L) decreases systemic blood flow
• tachypnea
• poor feeding
• poor perfusion
• may lead to hypoplastic left heart syndrome

Question 20

Hypoplastic left heart syndrome

Answer 20

• Cyanotic (R->L) decreases systemic blood flow
• mitral valve stenosis or atresia
• hypoplastic left ventricle
• aortic valve stenosis or atresia
• hypoplastic aortic arch
• dependent on ASD and PDA

Question 21

Angioma (2 types)

Answer 21

1. Capillary hemangioma (nevus vascularis): growth of SMALL capillary networks
2. Cavernous hemangioma: proliferation of LARGE dilated vascular channels

• Benign tumors, 10% in caucasian infants, consist of many endothelial cells
• vasculogenesis causes over proliferation of endothelial cells

Question 22

Coarctation of Aorta (2 types)

Answer 22

Aortic lumen beloew the origin of left subclavian artery is narrowed due to abnormal thickening of aortic wall. FREQUENT IN TURNER’S SYNDROME. Construction may be before or after ductus arteriosus

1. Postductal (adult): sometimes not noticed because collateral circulation is established though intercostal (intersegmental arteries)
2. Preductal: collaterals usually not well developed. After birth, little or no blood gets to lower body and legs unless ductus arteriosus remains open (can give PGE2 to help keep open), but many times the child dies if coarctation is severe)
   - can be caused by abnormal migration of smooth muscle into aorta, so when ductus arteriosis closes, smooth muscle also constrict, or possible abnormality of aortic arch remodeling

Question 23

Double Aortic arch

Answer 23

• persistence of distal portion of the right dorsal aorta
• forms vascular ring around trachea and esophagus
• stridor, respiratory infections, respiratory distress, wheezing, cough,
• esophageal complaints also common, including dysphagia, difficulty feeding, vomiting

Question 24

Interrupted Aortic arch

Answer 24

• both right and left 4th aortic arch arteries are obliterated
• distal right dorsal aorta is retained
• weakness, fatigue, poor feeding, rapid breathing, fast heart rate, low oxygen content (especially in legs and feet)
• right side always gets oxygen, left side of body is variable
• problem with neural crest migration
• > associated with DiGeorges syndrome: low calcium, developmental delay, immune system abnormalities

Question 25

Abnormal origin of right subclavian artery

Answer 25

• arises from the distal part of the right dorsal aorta and the 7th right intersegmental artery
• the right 4th aortic arch and the proximal part of the right dorsal aorta obliterate
• right subclavian passes behind esophagus and trachea
• > since subclavian artery goes through vertebral body, it can be compressed. You would see lower pulse/BP in RIGHT arm as compared to left

Question 26

Right arch of aorta

Answer 26

• the left 4th arch and left dorsal aorta are obliterated and replaced by the corresponding vessels on the right side
• > if ligamentum arteriosum lies on the left side and passes behind the esophagus, swallowing can be affected

Question 27

Left superior vena cava

Answer 27

• persistence of left anterior cardinal vein and obliteration of the common cardinal and proximal part of the anterior cardinal veins on the right

Question 28

Double superior vena cava

Answer 28

• persistence of the left anterior cardinal vein and failure of the left brachiocephalic vain to form

Question 29

Inferior vena cava abnormalities:

Answer 29

• Hepatic segment: right vitelline/hepatic veins and sinuses
• Prerenal: right subcardinal
• Renal: subcardinal-supracardinal anastimosis
• Postrenal: right supracardinal