Aortic Stenosis/PDA/Hypoplastic Left heart Flashcards by Meghan May

Normal aortic valve has:

____ cusps that are thin and mobile

Valve tissue attached to fibrous ring within _____ for support

aorta

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Aortic valve develops from 3
swellings of ____________
• Cavitation of these swellings
forms the thin valve leaflets
and sinuses of ________

subendocardial mesenchyme

Valsalva

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• Abnormal cavitation during aortic vavle devo results in

leaflet fusion and stenosis

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Congenital AS represents a wide spectrum of aortic valve pathology
• Stenosis is due to decreased _______
– Increased thickness and rigidity of ______
– Fusion of ________

orifice size

valve leaflets

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Unicuspid Aortic Valve

Unicommissural Aortic Valve

Bicuspid Aortic Valve

Stenotic Tricuspid Aortic Valve

are all examples of

Stenotic Aortic Valves

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Congenital Aortic Stenosis: Spectrum of Disease
• Congenitally malformed aortic valves represent a wide spectrum of disease
How does severity range?

Severity can range from mild clinically insignificant stenosis to severe life threatening stenosis which requires treatment as an infant

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Why is aortic stenosis described as a progressive disease?

Aortic stenosis worsens over time due to calcification and fibrosis of the valve leaflets
Aortic insufficiency may develop due to annular dilation and valve degeneration

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Effects of Aortic Valve obstruction include:

Hemodynamic abnomalities:

Aortic root dilitation, leaflet destruction, ventricular hypertrophy

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Aortic valve obstruction increases ________ and _______

LV pressure and wall stress

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Aortic valve obstruction causes increased LV pressure–> causing increased wall stress which results in:

compensatory LV hypertrophy as predicted by Laplace’s Law

*** LV hypertrophy reduces wall stress

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Severe aortic valve obstruciton eventually results in LV failure from:

from chronic ischemia
– ↑ Myocardial oxygen consumption (and less time in diastole)
– ↓ Myocardial oxygen supply

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2 month old with boy presents with progressive feeding intolerance manifested as fussiness with feeds, worsening reflux, decreased appetite and mild diaphoresis and tachypnea while feeding. He was noted to have a heart murmur at his 2 week well child visit.
• Exam demonstrates a healthy appearing infant with normal vital signs. Cardiac exam is notable for an LV heave and a III/VI harsh systolic cresendo-decresendo murmur heard at the right upper sternal border and radiating into the neck

What do you expect to see on echo?

• Echocardiogram demonstrates severe aortic valve stenosis

–harsh systolic cresendo-decresendo murmur at RUSB and radiates to neck

*see the calcified aortic vavle (shows bright white)

and LV dialates bc of volume overload

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In the tracing below, we have pt with aortic stenosis; Simultaneous left ventricular and aortic pressure tracings demonstrate a pressure gradient between the______ and _______ seen in the green shaded area

left ventricle and aorta

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In balloon valvuloplasty, operation to help with aortic stenosis, what do we worry about when performing? When do we perform this on kids with congenital aortic stenosis?

you can damage valve and cause insufficiency. At some point a child with congenital aortic stenosis will need surgery, but we try to limit surgeries and put this off for as long as possible

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Besides balloon valvuloplasty, what is another tx option for congenital aortic stenosis?

Surgical commissurotomy

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Mild-moderate AS has no effect on fetal circulation while severe AS results in an _______which reduces the flow of highly oxygenated blood from the umbilical vein into the LV and into the AAO

↑LVEDP

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• Severe AS results in an ↑LVEDP which reduces the flow of highly oxygenated blood from the umbilical vein into the LV and into the AAO thus umbilical venous blood high in O2 is
instead directed thru the_____ where it mixes with SVC blood which is low in O2 and then is directed thru the ________ and into the DAO and retrograde into the AAO
End Result:

ductus arteriosus

blood lower in O2 content supplying brain and coronary arteries

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Neonates with mild to severe AS have _____ post natal circulation

normal

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Neonates with critical AS are dependent on _____ for systemic blood flow

ductus arteirosus

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Fetal circulation is unique
_________ flow
 Oxygen-rich blood from placenta enters umbilical vein–>ductus venosus with
preferential flow–>PFO
 RV output _____%
 LV output ___%

Parallel

~60% RV output

~40% LV output

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Fetal circulation

 ~85% of RV output directed across_______
 ~_____% to the lungs
 ~___% of LV output directed across______

ductus arteriosus

~15% to lungs

~10%

aortic isthmus

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Why does the ductus arteriosus flow from the pulmonary artery to the descending aorta in the normal fetus?

The pulmonary vascular resistance is high

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The transition from fetal to
newborn circulation is critical
 Flow goes from ____ to ______
 Ductus venosus_____
 Lungs expand–>pulmonary vascular resistance ____

parellel to series

ducutus venous is ligated

drops

When we switch from fetal to newborn circulation:

 All RV output goes to the lungs–>increased LA flow; as LA pressures what happens to the fossa ovale?

fossa ovale flap valve closes

Newborn circulation when you transition from fetal to newborn circulation what happens to the ducutus arteriosus?

The ductus arteriosus spontaneously involutes and becomes a ligamentum

What should happen if the ductus arteriosus remains patent in the normal newborn?

Blood will now flow through the ductus arteriosus from the aorta to the pulmonary artery

If the ductus arteriosus remains open in an newborn we still see pulmonary resistance drop--\> Pressure in aorta becomes significantly higher than pressure in the pulmonary artery and the PDA creates:

L--\> R shunt through the PDA; blood flows from aorta to the pulmonary artery

What are the consequences to a newborn with a PDA?

The L--\>R shunt sends extra, already oxygenated blood back to lungs instead of to body--\> can lead to heart failure and poor growth

A newborn has a PDA, but blood continues to flow from the pulmonary artery to the aorta—how could you recognize this?

The baby’s legs would be blue \*R--\> L shunt

In the scenario described above, why would the PDA shunt continues to be right to left (ie from pulmonary artery to aorta) rather than left to right?

The resistance to flow into the lungs is higher than the resistance to flow into the body

If the ductus arteriosus remains open in an newborn and the infant develops heart failure the PDA should be closed 1. How is this acheived with meds? 2. How is this achieved surgically? 3. How can this be achieved without surgery?

medicine early after birth that promotes spontaneous involution (indomethacin)  This can be accomplished surgically through an incision in the left chest—suture ligation of the PDA  This can also be accomplished through placement of an obstructing coil or plug that closes off the PDA without surgery

The ductus arteriosus must remain open in an newborn with several forms of congenital heart disease in order for the infant to survive after birth: It provides blood flow to the lungs when there is severe obstruction to pulmonary blood flow

 Severe pulmonary stenosis or atresia  Right heart hypoplasia  Tricuspid stenosis or atresia

The ductus arteriosus must remain open in an newborn with several forms of congenital heart disease in order for the infant to survive after birth: It provides blood flow to the body when there is severe obstruction to the aortic blood flow in these conditions

 Severe aortic stenosis  Left heart hypoplasia  Coarctation of the aorta

The ductus can be kept open with a medicine that blocks spontaneous involution called:

PGE1; must be continuously infused into the body to maintain ductal patency, and so it is only a temporary treatment until the baby is stabilized and can undergo more definitive surgical treatment

Echo below is of newborn with cyanosis and poor pulses. Dx?

Hypoplast left heart syndrome

In hypoplastic left heart: LV hypoplasia with mitral/aortic valve hypoplasia/atresia While fetuses with HLHS do well infants rarely survive more than a week unless what two additional defects are present?

Atrial septal defect and patent ductus arteriosus

In hypoplastic left heart syndrome, a patent ductus arteriosus supplies: what structure helps get O2 to the body after birth?

PDA supplies Ao flow in fetus (R--\>L shunt) death with closure \* Foramen ovale empties LA (L--\>R) and must remain patent after birth to get O2to the body

This newborn has cyanosis (decreased oxygen levels) and good pulses. Based on Echo, whats the Dx?

Hypoplastic right heart syndrome

In hypoplastic right heart syndrome we see: What is the survival like for infants vs fetuses?

 RV hypoplasia with tricuspid/pulmonary valve hypoplasia/ atresia  Fetuses with this lesion also do well, but infants rarely survive more than a week, there is no blood flow to lungs

The 2 additional defects needed for survival after birth are the same in this heart lesion as in our other case with hypo left heart. What is different?

The atrial shunt is R--\>L and the PDA is L--\>R In hypoplastic left heart, the foramen ovale (btwn atria) is L--\>R the PDA is R--\> L

The ductus arteriosus is a critical structure in maintaining appropriate fetal flow patterns that allow

fetal blood to bypass the lungs \*\*\* Spontaneous closure occurs shortly after birth

Persistent patency of the ductus arteriosus (a PDA) can cause heart failure and poor growth in infants and children secondary to the:

L--\>R shunt

A PDA can be critical in many forms of congenital heart disease after birth where it is needed to supply:  Systemic blood flow when :  Pulmonary blood flow when :

there is severe obstruction to aortic flow there is severe obstruction to pulmonary flow

supplies Ao flow in fetus; results in death with closure in infants with HLHS (hypoplastic Left heart syndrome)

Ductus arteriosus

In HLHS, ______ empties LA and must remain patent after birth to get O2to the body

foramen ovale

What two structures are key to staying patent/open after birth of baby we see in this echo?

Echo shows HLHS, need foramen ovale and ductus arteriosus to stay open

HLS has variable presentation; we want to identigy these babies prenatal We usually see anomalies in a: If we see HLHS, what precautions do we take?

abnormal 4 chamber view on prenatal ultrasound – Allows for a smoother transition to post natal life, with the optimal scenario for the infant to be born at the center where the surgery is to be done

What murmur do we hear that is indicative of Hypoplastic LHS?

usually a soft I-II/VI SEM at the LUSB which radiates to the lungs and often mimics benign PPS – The heart sounds are often single and prominent (this is a very LUCKy method of diagnosis, as they may have 'normal murmur' and usually have mild cyanosis)

Because murmurs aren't the most sensitive ways to diagnose HLHS, what would be a more sensitive method?

A pulse oximitry test is more sensitive then getting lucky enough to hear the I-II/IV Systolic ejection murmur at the LUSB (radiates to lungs, mimics benign PPS)

BAbies with HLHS have variable Presentations: • Mild hypoxia unless \_\_\_\_\_\_\_

intact atrial septum –\*\*\*Usually very difficult to identify an oxygen saturation of 90-94% visually in a newborn infant

In a baby with HLHS you see mild hypoxia; what will be your only subtle hint of trouble?

An oxygen saturation that does not correct to normal without increased FIO2 \*\*\*Be careful as these infants SaO2 will increase to normal with Increased FIO2

In Infants with HLHS and intact atrial septum, the SaO2 will be

very low

Cardiogenic Shock in infant with HLHS occurs when: What are the signs of this?

the PDA is nearly fully closed

If a baby is going into cardiogenic shock from HLHS its when the PDA is nearly fully closed and the baby presents clincally the same way a child with what other conditions would?

Coarctation of aorta critical AS

What procedure is used for babies with HLHS?

Norwood procedure Glenn procedure: have the SVC feed right into pulmonary circulation to take stress off the RV and have the aorta connect to RV Fontan procedure: conduit to have the IVC bypass the RV and go right to pulmonary and have the aorta connect to the RV