Anatomy/Embryology of the Heart Flashcards
1
Q
Coronary Sulcus
A
(aka: AV Sulcus)
Contains:
- Arteries:
- RCA,
- Circumflex Branch of Left Coronary Artery;
- VENOUS:
- Coronary Sinus;
- Great Cardiac Vein
2
Q
Anterior Interventricular Sulcus
A
1) LAD (anterior interventricular artery): branch of L coronary atery
2) Great cardiac vein
3
Q
Posterior Interventricular Sulcus
A
1) right posterior descending artery (posterior interventricular artery): branch of RCA;
2) middle cardiac vein
4
Q
Formation of Atrial Septum
A
-
Stepum Primum: (thin, flexible) - begins to form at the end of the 4th week
- Grows from wall of atria toward endocardial cushions
- Gap between growing septum primum and endocardial cushion: Ostium (Foramen) Primum
- Ostium (Foramen) Secundum forms: perforation (apoptosis) in ostium primum to maintain communiation between L and R atria
- Ostium primum closes.
-
Septum Secundum: (thicker; rigid) - forms on R side of septum primum
- incomplete septum which covers ostium secundum, then stops
- Free edge of septum becomes: limbus of the fossa ovalis
- Portion of setpum primum not covered by septum secundum becomes Fossa ovalis
- bc septum primum is flexible, blood can pass from RA to LA (pressure gradient) through the Foramen Ovale
5
Q
Ventricular septum
A
Two Parts:
-
Muscular septum: develops with cardiac wall from cardiac muscle; partially separates L and R ventricles, with area of communication called the interventricular foramen
- forms during 5th week
- Membranous septum: formed from the aorticopulmonary septum and endocardial cushions
6
Q
Atrial Septum Defect: Primum Type
A
- ACYANOTIC - left to right shunt
- Septum Primum doesn’t fuse with endocardial cushion
- leaves patent ostium primum
- usually bc not enough NC cells migrated into endocardial cushion (thus, seen in association with NC defects)
- endocardial cushion contributes to valves
- second most common of the heart defects (ventricular is most common)
- most common defect of the acyanotic type
7
Q
Atrial Septal Defect: Secundum
A
- ACYANOTIC - left to right shunt
- More common than primum ASD
- ostium secundum not being covered over completely by septum secundum
- preventing complete closure of foramen ovale
8
Q
Ventricular Septum Defects
A
-
usually ACYANOTIC
- However a large L to R shunt may eventually result in overload of the pulm circuit, changes in pulm vasculatire and development of pulmonary HTN
- if Pressure in pulm circuit eventually rise > pressure in system circuit, the previous L to R shutn through VSD will reverse to
- R to L shunt = LATE CYANOSIS (Eisenmenger complex)
- However a large L to R shunt may eventually result in overload of the pulm circuit, changes in pulm vasculatire and development of pulmonary HTN
- in muscular or membranous septum
-
Muscular VSD
- result of excessive resorption of the embryonic ventricular septum during growth of the ventricle
-
Membranous VSD
- result of defective formation of aotricopulmonary septum; failure of this septum to fuse with embryonic ventricular septum
- more common
9
Q
Patent Ductus Arteriosis
A
- Failure of the ductus arteriosus to close = postnatal aorta to pulmonary (L to R) shunt
- ACYANOTIC
- more common in preterm babies: neonatal hypoxia and elevated prostaglandin levels contribute to this finding
-
Tx: inhibition of prostaglandin synthesis with indomethicin + O2 therapy
- gets PDA to close
10
Q
Tetrology of Fallot
A
most common heart defect
- CYANOSIS typically appears some time after birth
- caused by malpositioning of AORTICOPULMONARY SEPTUM
- formed displaced to the side of the truncus arteriosus and conus cordis (dextropositioning)
- Results in:
- pulmonary stenosis
- overriding aorta
- ventricular septal defect (bc aotricopulmonary septum does not fuse with the embryonic ventricular septum)
- right ventricular hypertrophy (develops secondarily)
*Pressure in RV is elevated, causeing RV blood to shunt through VSD into overriding aorta.
*R to L shunt –> CYANOSIS
11
Q
Persistant Truncus Arteriosus
A
- CYANOTIC
- aorticopulmonary septum does not form: truncus arteriosus persists rather than becoming ascending aorta and pulmonary trunk
- both ventricles empty their blood into this common artery
- deoxy and oxygenated blood is mixed –> CYANOSIS
- bc the absent aorticopulmonary septum would have contributed to the membranous ventricular septum, VSD coexists with persistent truncus arteriosus
12
Q
Transposition of the Great Arteries
A
- CYANOTIC
- most common cause of cyanosis presenting immediately after birth
- aorticopulmonary septum, which normally forms in a spiral shape, is not spiraled
- thus, aorta and pulmonary trunk are reversed from their normal positions
- RV flows into the aorta
- LV flows into the pulmonary trunk
- babies who remain alive after birth must have other defects that allow mixing of blood between the pulmonary and aortic circuit
- septal defects are common and PDA is typically seen in infants with transposition
13
Q
Prenatal IVC Flow
A
- more oxygenated IVC –> foramen ovale –> LA –> LV –> out LV to AA
- Kept separate from SVC to that the 3 branches of the aortic arch (below) can only be filled with IVC (more oxygenated blood to brain)
- brachiocephalic trunk
- left common carotid
- left subclavian
- this happens bc ductus arteriosus comes into the aorta just after the subclavian leaves the aorta
14
Q
Prenatal SVC
A
- deoxygenated SCV: RA –> very litte through foramen ovale (would have to make a U-turn to get through foramen ovale, so doesn’t) –> tricuspid –> RV –> out pulm trunk (vascular resistance is high in pulm cuircut bc not exapnded so very little in lungs) –> almost all shunts out of pulm circuit into aorta thorugh ductus arteriosus (R to L gradient) –> enters aorta and mixes with IVC in Ascending Aorta –> descending AA to umbilicles and to supply lower limbs
15
Q
Changes at Birth
A
- Ductus arteriosus –> ligamentum arteriosum
- Ductus venosus (liver) –> ligamentum venosum
- Umbilical vein –> ligamentum teres
- Right and left umbilical arteries –> medial umbilical ligaments
