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Flashcards in Twenty Three Deck (50)
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Describe the embryological developmental timeline of the heart.

 Week 3: Endocardial tube
has formed

 Driven by metabolic needs exceeding diffusion alone

 Bordered by aortic arches rostrally, venous system

 Day 22-23: begins to beat

 Day 23: tube bends to right

 Constrictions form in tube
 Separates truncus arteriosus, bulbus cordis,
ventricle, atrium, and sinus venosus
 AV canal separates atrium and ventricle

 Week 4: Ventricle begins to grow and septate (from apex)

 Week 5: Spiraling of aorticopulmonary septum and formation of outlet ventricular septum

 Weeks 4-6: Development of atrial septum


Describe the epidemiology of CHD?

 Most common cause of heart disease in children

 ~1% incidence

 Most common organ malformed at birth

 10% of early miscarriages

 Spectrum of presentation and severity
 Asymptomatic through childhood
 Death in infancy without immediate treatment
 Everything in between


Describe the etiology of CHD?

 Why?

 Majority: “Multifactoral”

 Genetic + environmental

 Genetics
 Recurrence risk
 Syndromes
 ~1/3 children with chromosomal abnormalities

 Maternal risks
 Maternal diabetes

 Teratogens
 Alcohol, lithium, etc.

 Congenital infections
 Congenital rubella


Describe the pathway of oxygenated blood.

 Oxygenated blood:

1. Placenta

 Umbilical vein to:

 Ductus venosus to:

 Inferior vena cava to:

 Right atrium to:

 Foramen ovale to:

 Left atrium to:

 Coronary arteries, brain


What are the ductus venosus, foramen ovale, and ductus arteriosus?

2. Ductus venosus-A way for oxygenated blood from the placenta to bypass the liver.

3. Foramen ovale-A way for blood to bypass pulmonary circulation (connects RA and LA)

4. Ductus arteriosus-Another way for blood to bypass pulmonary circulation (connects PA with Aorta)


Describe the resistance of both pulmonary and systemic vasculature in fetal circulation.

 Systemic Vasculature:
 Placenta: very high vascular cross sectional area
 = “low” systemic vascular resistance (SVR)

 Pulmonary Vasculature:
 Lungs deflated (fluid-filled)
 Low oxygen tension
 = “high” pulmonary vascular resistance (PVR)


Describe the CO of the fetal heart? Where does it leave and where does it go?

 Where does fetal blood go?

 Right ventricle: ~2/3 of fetal

cardiac output

 12% of flow to lungs

 88% of flow to descending aorta

 Left ventricle: ~1/3 of fetal

cardiac output

 9% of flow to coronary arteries

 62% of flow to carotid-
subclavian arteries

 29% of flow to descending aorta


How and why does circulation change in a newborn?

 Systemic Vasculature:
 Umbilical vessels constrict
 Increases SVR

 Pulmonary Vasculature:
 Lungs inflate, pulling open pulmonary vasculature
 Oxygen increases
 Decreases PVR

 Increased pulmonary flow increases LV stroke volume
 LV cardiac output = RV cardiac output


What happens to the foramen ovale and ductus arteriosus after birth?

 Foramen ovale
 Decreasing PVR increases pulmonary blood flow
 Increased left atrial filling
 Foramen flap closes

 Ductus arteriosus
 Endogenous prostaglandin E1 (PGE1) decreases
 Increased oxygen tension
 Stimulates ductal closure


What happens to the individual ventricles after birth and why? How much time?

 Higher SVR = thickeningof LV

 Lower PVR = thinning of RV

 LV:RV Weight Ratio

Age Ratio

Birth 0.8:1

1 Month 1.5:1

6 Months 2:1

Adult 2.5:1


What is cyanosis? What are the two possible cardiac causes of it?

 Strict definition:

 > 4 g/dL deoxygenated


 Cardiac causes:

 Inadequate pulmonary blood flow (lack of

 Mixing of systemic venous (blue) blood into systemic
arterial (red) blood


What are the three paired fetal veins? What do they do?

 3 paired veins in embryo:

a) Vitelline veins (return from yolk sac)

b) Umbilical veins (return from placenta)

c) Cardinal veins (return from body of embryo)
 Anterior and posterior
(subcardinal, supracardinal) cardinal veins


What fetal veins do the IVC and SVC come from? Why is this important to note?

 Superior vena cava:

 Right anterior cardinal vein

 Bridging vein between anterior

cardinal veins becomes

brachiocephalic vein

 Inferior vena cava:

1. Hepatic and subhepatic segments (vitelline vein)

2. Prerenal segment (right subcardinal vein)

3. Renal segment (subcardinal-
supracardinal anastamosis)

4. Postrenal segment (right supracardinal vein)

It's signinficant b/c the IVC comes from many different fetal veins which means that various factors can lead to a deformed IVC.


What is a persistent left SVC? What is the vasculature like? Is it cyanotic or acyanotic?

 Persistent Left SVC: persistence of left anterior cardinal vein

 Drains to coronary sinus
 Acyaontic.


What is an interuppted IVC? What is the vasculature like? Is it acyanotic or cyanotic?

 Interrupted IVC: absence of a contribution of IVC
development (most commonly hepatic segment)

 IVC drains into azygous system

 Acyanotic?


Describe the development of pulmonary veins.

 Vascular plexus of foregut enmeshes lung buds (connections to

cardinal and vitelline systems)

 Evagination in posterior wall of left atrium

 “Common pulmonary vein” connects LA to foregut plexus

 Systemic connections involute


What is TAPVR? What is the vasculature like? What are the three types? Is it acyanotic or cyanotic?

 Pathology: Total

Anomalous Pulmonary

Venous Return (TAPVR)

 Lack of connection to LA,

persistence of connections to

cardinal/vitelline veins

 3 types:

1. Supracardiac: Drain above

2. Cardiac: Drain back to

3. Infracardiac: Drain below

heart (often SVC)

heart (often coronary


heart (often IVC/hepatic



What occurs when TAPVR involves obstructed pulmonary veins? Clinical implications? Unobstructed? Clinical implications

 “Obstructed” pulmonary veins (usually in infracardiac due to the diaphragm).

 Profoundly cyanotic, unstable

 Surgical emergency

 “Unobstructed”

pulmonary veins

 Cyanotic (mixed systemic

and pulmonary veins)

 Repaired 1st

month of life


Describe atrial septal development. What happens at birth?

 Atrial Septum:


 Goal: allow fetal shunt that

closes at birth

1. Septum primum: grows

 Leaves ostium primum

 Perforations in septum

 Fuses with endocardial

from roof towards

endocardial cushions

between septum primum

and endocardial cushion

primum form ostium


cushion to close ostium


2. Septum secundum:

grows to right of septum

primum, covering

ostium secundum

 Leaves foramen ovale

 “Flap” of foramen ovale

on LA side from septum


 At birth: increased

pulmonary flow

increases LA flow, closes



What is a patent foramen ovale? How common is it? What is it like clinically?

 Intact septum

 Remnant of PFO flap:

fossa ovalis

 “Patent” foramen ovale

present in 15-20% of the


 No pathologic

significance unless. . .

 Avenue for a clot to pass

from systemic veins to

systemic arteries

• “Paradoxic” embolus


What is the pathology of an ASD? Cyanotic or acyanotic? What are the three distinct types? What symptoms are there? What will be found on exam? How are the distinct types treated?

 Pathology: Atrial Septal Defect (ASD)
 Due to deficiency of septal tissue
 Acyanotic

 3 distinct types:

1. Sinus venosus (10%)
 Often with RUPV PAPVR

2. Ostium secundum (60%)
 Involves fossa ovalis

3. Ostium primum (30%)
 Involves endocardial cushion

 Symptoms: ~lower side of growth curve

 Physical exam:
 Systolic ejection murmur at LUSB (pulmonary flow
 Fixed split S2

 No symptoms = no medications

 ~40% secundum ASD close by age 4 years

 Surgery (primum, sinus

venosus, some secundum)

 Interventional cath



Describe the development of the AV valves.

 Endocardial Cushions (EDC): Development

 “Atrioventricular canal” = junction of atrium and ventricle

 Endocardial cushions (EDC) form dorsal/ventral to
separate canal into 2 canals (right/left)

 EDC also contributes to:
 Atrial septum (fuses with septum primum to close
ostium primum)
 Ventricular septum (inlet portion)

Mitral and Tricuspid Valves: Development

 Proliferation of tissue around AV canals

 “Delamination:” valves “peel” off ventricular endocardial
surface (anchored at hinge point)


What is an AVC? What are the different names for it? What are the two different kinds? What is it commonly associated with?

Atrioventricular Canal

Defect (AVC)

 Embryology: lack of fusion of endocardial cushions

 Endocardial cushion defect (ECD) = atrioventricular
canal defect (AVC) = atrioventricular septal defect (AVSD)

 “Complete” versus “partial” AV canal defect

 Commonly associated with

Down syndrome


Describe the pathology of complete AVC? Acyanotic or cyanotic? What are the symptoms? Physical exam findings? Treatment?

a) “Complete” Atrioventricular Canal Defect

 Lack of fusion of entire endocardial cushion

 Results in:

1. Ostium primum atrial septal defect (ASD)
2. Common atrioventricular valve spanning both ventricles
3. Inlet ventricular septal defect (VSD)

 Acyanotic

“Holosystolic” murmur
 Pitch/volume varies based on pressure difference
from LV to RV

 Symptoms: pulmonary overcirculation (related to VSD)
 Tachypnea, tachycardia
 Poor feeding = poor weight gain
 Increased catechols = diaphoresis

 Treatment:

 Symptomatic medications:
 Diuretics (dry out lungs)
 Digoxin (augment contractility)?
 ACE-inhibitor (afterload reduction)
 Augment nutrition (increasing caloric density of formula)
 Surgical closure (~4-6 months)


Describe partial AVC. Cyanotic? What are the syptoms? Exam Findings? Treatment?

b) “Partial” Atrioventricular Canal Defect
 Incomplete fusion in a portion of endocardial cushion

 Results in:

1. Ostium primum ASD

2. Cleft in anterior leaflet of mitral valve

 Acyanotic

 Symptoms: ~lower side of growth curve

 Physical exam:
 Systolic ejection murmur at LUSB (pulmonary flow murmur)
 Fixed split S2
 +/- holosystolic murmur at apex (mitral regurgitation)

 Treatment:
 No symptoms = no medications
 Surgical repair (ASD closure, cleft closure) ~2 years


Describe the vasculature and bloodflow in tricuspid atresia. Treatment?

2) Pathology: Tricuspid


 Atresia = absence of a

normal opening

 Clinical:

 Where does right atrial

blood go?

 ASD (right to left)

 How does blood get to lungs?

 VSD to right ventricle

 cyanotic

 Treatment: single ventricle palliation


What is the pathology of ebsteins anomaly? What is the resulting vasculature? What risk factor is it associated with? Cyanotic? Treatment?

3) Pathology: Ebstein’s Anomaly

 Failure of delamination of

tricuspid valve

 Results in leaflets “stuck”in body of RV

 Significant tricuspid regurgitation

 Varying degrees of


 Association: maternal lithium (teratogen)

 Clinical: May be acyanotic or cyanotic
 Depends on severity of delamination failure

 Treatment: tricuspid valve repair if significant


Describe ventricular septal development.

 Ventricular Septum: Development

 Week 4: muscular

ventricular septum grows

up from apex

 “Excavation” of ventricles

 Leaves interventricular

foramen (above)

 Endocardial cushion

forms inlet portion

 Week 5: “Bulbar ridges”

grow from outflow tracts

 Week 8: fusion of


septum (membranous



What are the 4 regions of the ventricular septum?

 Ventricular septum

composed of 4 regions:

1. Inlet (EDC)

2. Outlet (Bulbar)

3. Trabecular (Muscular)

4. Membranous (Fusion point)


How common is a VSD? What is their etiology? Cyanotic? Symptoms? Exam Findings? Treatment?

1) Pathology: Ventricular

Septal Defect (VSD)

 Most common congenital

heart defect

 Isolated VSD’s: ~20% of all CHD

 VSD’s occur due to:

1. Malalignment of portions

of septum (adequate


2. Deficiency in tissue

(congenital vs traumatic

vs MI)

 Acyanotic

“Holosystolic” murmur at LLSB

 Pitch/volume varies based on pressure difference from
LV to RV

 Murmur and symptoms:when?

 Newborn: higher PVR limits shunting

 ~2 months of age: PVR has dropped low enough
to allow significant shunting

 Symptoms: pulmonary overcirculation (related to VSD)

 Tachypnea, tachycardia

 Poor feeding = poor weight gain

 Increased catechols = diaphoresis

 Treatment:

 Symptomatic medications:

 Diuretics (dry out lungs)

 Digoxin (augment contractility)

 ACE-inhibitor (afterload reduction)

 Augment nutrition (increasing caloric density
of formula)

 Surgical closure (~4-6 months)
versus cath device closure