OB week 2

Embryology

• paired tubular structures fuse at 22 days
• caudal portion bends to form atrioventricular loop, develops a single common atrium,
• the space between the R/L atrium is called the ostium primum; is disappears when...
• septum primum develops along the cephalad portion of the atrium and toward the endocardial cushions
• before complete fusion, ostium secundum forms, opening within it is foramen ovale
• the great vessels arise from the common trunk - truncus arteriosus
• week 7: twisting forms aorticopulmonary septum
• days 19-30: long process with many pairs to form aorta and pulmonary arches

Fetal Circulation

• placenta is sole source of oxygen for fetus
• oxy blood in placenta --> umbilical vein --> ductus venosus/IVC/SVC --> rt atrium --> foramen ovale --> Lt atrium --> Lt ventricle --> aorta --> distal arteries --> umbilical artery --> placenta
• OR
• rt atrium --> rt ventricle -- >pulmonary artery --> ductus arteriosis --> descending aorta --> distal ateries --> umbilical artery -- > placenta

Slide 3

• What are some of the things we are looking for or assessing when evaluating a 2D echo?
• what is a normal fetal heart rate?
• what are PAC's, PVC's?
• what are PAC's associated with?
• define tachycardia.
• name the 3 categories of SVTs
• what are SVTs associated with?
• define bradycardia?
• what is congenital heart block?
• what maternal disorder is it associated with?
• what is complete heart block?
• 40% of complete heart block fetuses have?
• how do we check for situs?
• what is levocardia?
• what is dextrocardia?
• what is dextroposition?
• what is mesocardia?
• which situs is associated with chest masses?
• Answers
• situs, viability, 4CH, ventricular/atrial septae, LVOT, RVOT, 3VV, aortic arch, ductal arch
• 120-180 BPM; 100-120 at 5.5-6 wks; 170 by 9-10 wks; 130 by term
• abnormal atrial and ventricular contractions originating from locations other than the sinus node
• PAC's ass.c redundancy of foramen ovale membrane, caffeine, smoking, multiple pregnancies
• heart rate greater than 180 BPM supraventricular tachycardias (SVTs) more common than ventricular tachycardia
• a) paroxysmal supraventricular tach-: atrial rate 180-300, conduction rate 1:1
• b) atrial flutter: atrial rate 300-400 conduction rate 2:1-4:1...ass.c heart block
• c) atrial fibrillation: atrial rate >400, irregular vent rate 120-160;
• ventricular tach. is rapid heart rate associated with >3 consecutive premature ventricular systoles
• structural cardiac lesions 10%; can lead to hydrops and death;
• prolonged FHR
• failure of transmission of impulses from atrium to ventricles; immature/absent conduction system
• maternal collagen vascular disease (systemic lupus erythematosus
• complete disassociation between atrial and vent. rates (odd ratios). ass.c non-immune hydrops
• structural cardiac anomalies, prognosis is poor
• stomach and heart on Lt side ?
• normal position of heart on left side of chest
• apex is directed rightward, heart is primarily in right chest
• heart in normal axis, displaced to the right by external process (e.g. left-sided chest mass)
• heart is central with apex pointing anteriorly
• dextroposition