Anatomy Of Congenital Heart Disease

Front 1

What is Congenital heart disease? How common is it?

Back 1

*Abnormalities of the heart and great vessels that are present from birth:
-Severe abnormalities are incompatible with life.
-Some require intrauterine intervention.
~50% diagnosed in the first year of life.
-Some become evident by the change from fetal to postnatal circulatory pattern.
-Some may not become evident until adulthood.

*Incidence: 1%.

*Most common type of heart disease among children.

Front 2

Etiology of CHD:

Back 2

*Single-gene or chromosomal mechanisms.

*Environmental factors (e.g. rubella virus, acne treatment).

*In most of the cases it is multifactorial (environmental, genetic, etc.).

Front 3

Discuss Cardiac Genetic Programming:

Back 3

*A complex subject under intensive investigation.

*Must involve myriad genes, many (or most) of which are not cardiac-specific.

*Must consider genes related to anatomical development as well as production of all the proteins concerned with contraction, pacemaking, conduction (e.g. myosin, dystrophin, troponin T and I).

Front 4

Quick diagram review of Cardiac development:
Days 15, 21, 28, 50.

Back 4

Front 5

Cardiac development with transcription factors and miRNAs identified:

Back 5

*Tbx1 is the only one she mentioned; an important transcription factor for the outflow tract.

Front 6

What is the Etiology and pathogenesis of CHD? 4

Back 6

*Single gene mutations.

*Small chromosomal deletions (22q11.2).

*Aneuploidies (monosomy X [Turner syndrome and aortic coarctation], trisomies 13, 18 and 21):
-Trisomy 21 is the most common genetic cause of CHD.

*Environmental (rubella [PDA], diabetes, etc.).

*Most are SPORADIC.

Front 7

Table of genetic causes of CHD:

Back 7

*DiGeorge is a big one (TBX1 mutation)

Front 8

Table of frequencies of congenital heart malformation in live births:

Back 8

*VSD most common with LIVE births (still births are another matter). Most close on their own in the first year of life.

Front 9

Describe the Fetal circulation:
-What are the 3 oxygenated blood bypasses?

Back 9

*Oxygenated blood bypasses:
-liver via the ductus venosus
-lungs via the foramen ovale and ductus arteriosus.

Front 10

Describe the Neonatal circulation?

Back 10

*1st breath: clears the airway reducing the pressure within the pulmonary vascular beds.

*Lower pulmonary pressure causes blood to enter the lungs instead of passing through DA.

*Blood rushes from the lungs into the LA and presses the septum primum against the septum secundum.

Front 11

Discuss the Closing of the DA and FO:

Back 11

*In neonates born at 26 weeks to term, functional ductal closure in 10%, 60%, 85%, and 97% on days 1, 2, 3, and 4.

*Functional closure of the foramen ovale as soon as LA pressure exceeds RA pressure; anatomical closure takes a long time and 1/3 of adults have a patent foramen ovale.

Front 12

Describe the Classification of CHDs: 3 categories; briefly explain each--

Back 12

*Malformations causing a left-to-right shunt:
-Increased pulmonary blood flow.
-RV hypertrophy and atherosclerosis of pulmonary vasculature.
-Pulmonary arterial vasoconstriction.
-Pulmonary vascular resistance approaches systemic levels --> right-to-left shunt (Eisenmenger syndrome).

*Malformations causing a right-to-left shunt:
-Cyanotic heart disease (5 Ts).

*Malformations causing an obstruction.

Front 13

Diagrams of the 5 Left-to-right shunts:

Back 13

Front 14

ID.

Back 14

*Left: Arrow points to membranous part of IV septum (derives from what? bulbus!)

*Right: Paramembranous VSD; i.e. a defect where the membranous septum is supposed to be.

Front 15

ID. How common is it? What are the sx?

Back 15

*Membranous VSD. Most common type of VSD.

*Sx depend on size of defect. Small may be asymtomatic; large ones can result in significant shunting.

Front 16

Diagrams of muscular VSDs:

Back 16

Front 17

ID.

Back 17

Muscular VSD. Most close within a year of life on their own.

Front 18

Diagrams of Atrial septal defects (ASDs): 3 of them--

Back 18

*These are named by the embryological origin of the defect (like sinus venosus defect, etc.).

Front 19

What's the most common form of ASD?

Back 19

*Probe patent foramen ovale= functional closing of foramen ovale, but it's still open if you probe it. Not really significant.

Front 20

?

Back 20

Probe patent foramen ovale. The left atrial cavity is open. A probe has been inserted into the LA from the RA via a patent foramen ovale.

Front 21

Back 21

RA – patent foramen ovale; more severe than the "probe" variant.

Front 22

ID.

Back 22

Front 23

Diagrams of a PDA and its pathophysiology:

Back 23

Front 24

Diagram of Atrioventricular septal defects:
AKA?

Back 24

AKA endocardial cushion defect. HUGE opening; this is bad.

Front 25

Diagrams of AV canal defect:
What's it commonly associated with?

Back 25

*Commonly associated with trisomy 21.

Front 26

ID.

Back 26

AV communis from a T21 case. Autopsy specimen.

Front 27

ID:

Back 27

Stillborn.

Front 28

List the Right-to-left shunts: 5

Back 28

*Tetralogy of Fallot (most common cause of early cyanosis).

*Transposition of great arteries.

*Truncus arteriosus.

*Tricuspid atresia.

*Total anomalous pulmonary venous return (TAPVR).

**The 5 Ts**

Front 29

What are the Spiral septum defects? 3

Back 29

*Persistent truncus arteriosus:
-Spiral septum is not developed.

*Transposition of great vessels:
-Spiral septum does not take a spiral course.

*Tetralogy of Fallot:
-Spiral septum divides the truncus arteriosus unequally.

Front 30

Describe Tetralogy of Fallot:

What are the 4 components of it?

Back 30

*Anterosuperior displacement of the infundibular septum:

-Pulmonary stenosis (most important)
-Right ventricular hypertrophy.
-Overriding aorta (overrides the VSD).
-VSD.

Front 31

ID.

Back 31

*Normal anatomy of the right ventricular outflow tract (RVOT):
-pv = pulmonary valve
-pb = parietal band
-sb = septal band

*Must be understood to understand tetralogy of Fallot.

Front 32

ID.

Back 32

*Normal anatomy of the right ventricular outflow tract (RVOT): *Must be understood to understand tetralogy of Fallot.

*Note superior and inferior limbs of septal band.

Front 33

ID.

Back 33

Tetralogy of Fallot. Note septal band and parietal band and the conoventricular septal defect (*).

Front 34

ID.

Back 34

Transposition of great arteries

Front 35

What are the two variants of Transposition of great arteries?

Back 35

*With a shunt (left), babies can survive.

Front 36

Diagrams of Persistent truncus arteriosus:

Back 36

*Note the VSD.

Front 37

ID.

Back 37

*Persistent Truncus arteriosus.

Left: Probe is in IVC-SVC.
Right: Quadricuspid truncal valve; Subvalvular VSD (vertical slit on right).

Front 38

ID.

Back 38

Persistent Truncus Arteriosus. Not compatible with life.

Front 39

What are the congenital Obstructive anomalies? 3

Back 39

*Coarctation of the aorta
*Atresia of AV valve
*Atresia of semilunar valves (not compatible with life, unless there's a shunt).

*Usually these present with other malformations.

Front 40

Diagrams of Coarctation of the aorta:

Back 40

*Preductal--some blood goes to lower extremities.
*Postductal--might have loss of blood to the legs (can't feel femoral pulses).

Front 41

Coarctation of aorta diagrams with and without PDA.

Back 41

Front 42

Other malformations we may see in babies? List 4

Back 42

*Persistent left superior vena cava
*Aberrant origin of the right subclavian artery
*Ectopia cordis
*Dextrocardia

*Not huge clinical impacts.

Front 43

ID.

Back 43

*Heart with Thymus removed.
*Note innominate (brachiocephalic) vein. This means there is NOT a persistent left Vena Cava.

Front 44

ID.

Back 44

Absent innominate vein. Persistent left superior vena cava (*).

Front 45

ID and discuss.

Back 45

*NORMAL origin of the right subclavian artery.

*Aortic arch branching as seen from posterior aspect; right to left – innominate (IA), LCCA, LSA.

*If RSA is not a branch of the IA, it will be a 4th branch and will go to the right in a retroesophageal route.

Front 46

ID and discuss.

Back 46

*ABERRANT origin of the right subclavian artery.
*Left: Probe is under an ARSA.
*Right: ARSA is retroesophageal.

Front 47

ID and discuss:

Back 47

*Common origin of the carotid arteries (COCA), a frequent variant (no clinical significance).

Front 48

Discuss Laterality (Looping):

Back 48

*An asymmetrical axial signaling system determines cardiac looping as well as the position of other organs.

*This directs asymmetrical expression of Sonic hedgehog and Nodal in the lateral mesoderm.

*Interpretation of L-R signals is mediated, at least in part, by a TF, Ptx2, which is expressed along the left side of developing organs.

*Leads to "situs invertus."