Congenital Heart Disease 1 Flashcards
What is the prevalence of congenital cardiovascular malformations in USA live-born infants?
5-8 per 1,000
0.5-0.8%
What gender is more likely to have severe congenital heart disease?
Males
True or False: African americans are more likely to have congenital heart disease
False. There is no difference in race, parental age, or marital status
True or False: Maternal diabetes is a risk factor for congenital cardiovascular disease
True. 3x risk
Fetal echo recommended in this subpopulation of patients
True or False: Family history of cardiac defect in a first degree relative (parent or sibling) is a major risk factor
True
For family history of PAD or PFO, this typically isn’t severe enough to warrant screening. It’s typically the more complicated cardiac birth defects that we decide to screen future births and siblings for
What is the prevalence of the following defects? Per 10,000 live births
- VSD
- PDA
- TOF
- ASD
- Coarctation of the aorta
VSD - 15.6 per 10,000 PDA - 5 TOF - 2.6 ASD - 2.35 Coarctation of the aorta - 1.39
What keeps the ductus arteriosus open?
Prostaglandins: a product of the metabolism of arachidonic acid; potent vasoactive agent.
Prostaglandins are produced by the placenta. In utero, ductus is kept open by this exposure.
Site of production is not entirely understood. In addition to the placenta, it is thought to be locally produced at the ductal wall.
Administration of prostaglandin (PGE1) through IV will maintain ductal patency postnatally which can be beneficial to compensate for other congenital heart defects. It can be kept open for as long as you need it to be as long as they are on the IV PGE.
What is a shunt?
A connection between 2 chambers/vessels
What determines the direction of blood flow through a shunt?
Pressure or resistance difference between the 2 chambers
In standard shunt nomenclature, what is a left-to-right shunt?
This is blood flow from a systemic chamber into a pulmonary chamber
Systemic chambers: Pulmonary veins, left atrium, left ventricle, aorta
Pulmonary chambers: Systemic veins, right atrium, right ventricle, pulmonary arteries
The magnitude of a shunt across a PDA is based on what 3 factors?
- Size of PDA
- Relative resistances of the aorta and pulmonary artery
- Pressure differences between the aorta and pulmonary artery
In PDA, what direction shunt is most common?
Left to right, because the pressure and resistance of aorta is greater than the pulmonary resistance or pressure.
What are the symptoms of PDA?
Small PDA is asymptomatic.
Moderate to large PDA have symptoms within the first couple days (especially preterm infants).
You will see symptoms that are consistent with increased pulmonary blood flow and decreased systemic blood flow.
- Difficulty weaning off ventilator
- Pulmonary edema/hemorrhage
- Congestive Heart Failure
- Feeding intolerence (can lead to bowel ischemia - necrotizing enterocolitis which is life threatening)
- Renal insufficiency (not enough blood flow to kidneys)
- Intraventricular hemorrhage or stroke
- Death (Rarely)
Older infants or young children can have specific clinical presentation.
Hoarse cry
History of pneumonias
Failure to thrive
Labored breathing and diaphoresis with activity/feeding
Note that even a large ductus can be asymptomatic in an older child. (subtle exercise intolerance or frequent “infections”/asthma)
What are 5 physical exam findings of a large PDA with left-to-right flow in a neonate?
- Wide pulse pressure (lower diastolic BP because blood typically travels through the aorta during diastole but with PDA it will escape into the pulmonary artery)
- Bounding pulses (palpable palmar pulses)
- Increased work of breathing
- Hyperactive precordium
- Murmur- variable
What murmurs can you hear with PDA?
Classic: Continuous or machinery sounding murmur along the left upper sternal border. Can be associated with a diastolic rumble if the shunt is large. It’s continuous because throughout all parts of the cardiac cycle, the left side is higher pressure so there is always left to right shunt.
If the velocity is low or if the shunt is tiny, there won’t be murmur. (this is most dangerous because you won’t find it)
An accentuated P2 component of the heart sounds if there is associated pulmonary hypertension.
What is A2 and P2?
A2 is aortic valvue closure and P2 is pulmonary valve closure (both make up the S2 heart sound)
What tools do you use to diagnose PDA?
Can often have an idea of what’s going on from history and physical exam. You can confirm with imaging.
Chest radiograph - typically looks normal if the PDA is small. You may see increased pulmonary vascular markings and an enlarged left atrium and left ventricle if the PDA is large.
Echocardiogram can confirm for sure.
How do you manage a patient with PDA?
Depends on the age of the patient and symptoms.
Asymptomatic neonate => conservative management. just wait and see if it closes
Symptomatic neonate => try cyclooxyrgenase inhibitors (NSAIDS - delivered IV). If medication fails, try surgical ligation via lateral thoracotomy. Can be done bedside in the NICU
Symptomatic older child or large ductus in an older child => percutaneous occlusion
Asymptomatic older child => controversial** this isn’t testable
- murmur => percutaneous closure
- silent => no need to intervene
Controversy is whether or not a silent ductus has an increased risk of bacterial endocarditis (SBE)
Why do you treat symptomatic neonate PAD with NSAIDs?
Because NSAIDS are COX inhibitors and block conversion of arachidonic acid to prostaglandin.
NSAID treatment doesn’t work on the older kids. This is most effective in the first week of life and in preterm infants. Usually you wait until after the first two days though to see if there is spontaneous closure.
How often do NSAIDs work in treating neonate PAD?
This works 70% of the time in closing PDA in preterm neonates. Indomethacin and ibuprofen have equal efficacy
When would you use ibuprofen over indocin and vice versa?
Indocin is protective against intraventricular hemorrhage, but results in decreased blood flow to kidneys and brain. So, Ibuprofen Lysine is preferred in the setting of renal disease/insufficiency.
How do you do percutaneous ductal occlusion?
Catheter is put through from the femoral artery and threaded up the aorta. Contrast is used to fill the aorta and you can also see it travel across the ductus arteriosus. You put another catheter into the femoral vein up all the way to the pulmonary artery and position the spindle to plug the ductus. You inject contrast again from the aorta and no longer see contrast going into the pulmonary artery from the ductus arteriosus.
Which shunts are most prone to bacterial endocarditis?
Ones with higher velocity
What is ASD?
Atrial septal defect. This is a hole that exist in between the left and the right atrium.
When does the atrial septum form?
Days 28-42 (post-loop stage)
How does the atrial septum form?
In the middle of the primitive atria, you have a curtain like growth that is called the septum primum. As it grows, the negative/empty space is called the ostium primum. As the septum primum grows across the cavity, the ostium primum disappears. There is apoptosis in the middle of the septum primum which creates the ostium secundum. This turns into the foramen ovale and a second septum curtain layer called the septum secundum grows across the cavity. The foramen ovale is a hole through both septum primum and secundum.
In the primitive atrium, which side does septum primum end up on and which side does septum secundum end up on?
Primum ends up on left and secundum ends up on the right
What are endocardial cushions?
They sit where the mitral and tricuspid valves will form. The septum primum fuses with these endocardial cushions
What % of all congenital heart defects is ASD?
7-8%
What is the embryologic basis of ASD?
The ostium secundum in the septum primum is too large. OR there is inadequate development of the septum secundum.
What is considered a “large defect” for ASD?
If the diameter of the opening is equal to or greater than that of the mitral valve
Is there more risk of the LA and RA pressures equalizing if the ASD is large or small?
Large
True or False: ASD is typically detected during infancy
FALSE. It’s typically asymptomatic during infancy because LV and RV myocardium are similar immediately after birth with similar inflow resistance which causes minimal atrial level shunt.
Remember, the flow through the defect is due to a difference in pressure and resistance. In utero, the lungs are full of fluid and, for the most part, are bypassed. The ventricles develop about the same size and it isn’t until the baby is born that the LV starts to get bigger and stiffer in comparison to the RV. As the LV get stiffer, compliance goes down, and the amount of pressure it would take to create an increase in volume is greater, so some blood would rather travel through the defect than through the LV.
What are the physical exam findings for a small ASD?
Small defect with no/minimal shunt or neonate may have normal exam.
What are the physical exam findings for a large ASD? (4 things)
Large defects may present with:
- In infancy, increased RR, sweating with feeds, but may also still be asymptomatic.
- Liver 2-3 cm below right costal margin (More blood flowing into right atrium which causes back flow)
- . 2-3/6 systolic ejection murmur at the upper left sternal border +/- diastolic rumble at lower left sternal border
- Second heart sound is widely split
What causes the murmur in the ASD?
NOT the blood flowing across the defect.
The 2-3/6 systolic ejection murmur at the upper left sternal border is excessive blow flow across the pulmonary valve. This is because some of the blood in the LA is shunted to the RA which goes to the RV and causes excess blood flow across the Pulmonary Valve.
There may also be a diastolic rumble at the lower left sternal border. This is excessive blood flow in diastole across the tricuspid valve. During diastole, blood typically flows from Atrium to Ventricle. And in ASD, there is extra blood from the LA going to the RA which causes more blood flow to cross the tricuspid valve causing the murmur.
Why is there a widely split S2 in ASD?
S2 sound is made of A2 and P2. During inspiration, the A2-P2 split is more prominent because the negative intrathoracic pressure increases right heart filling-delaying RV emptying and P2 closure.
With ASD, RV volume overload secondary to the ASD results in delayed RV emptying and therefore a wide splitting of S2 in all phases of respiration
What are diagnostic tools for ASD?
Echocardiography is diagnostic.
- Size and location of defect
- Magnitude of shunt
- Associated lesions
Chest radiograph (not really used) would have findings:
Heart is of variable size depending on degree of shunting
The main pulmonary artery is enlarged
Pulmonary vascular markings are prominent
True or false: ASD is often undetected in childhood.
True
What are the long term risks of a hemodynamically significant ASD? (3 things)
- Development of pulmonary vascular disease
- Occurrence of atrial arrhythmias
- Onset of cardiac failure
What is pulmonary vascular disease?
High pulmonary blood flow results in increased pulmonary vascular resistance. This is a risk of all large, left-to-right shunt lesions that aren’t fixed. This is irreversible and life threatening.
This typically takes years-decades to happen. It’s unusual in childhood
Of patients who have shunt defects, how many develop PVD?
5-10%
Typically happens in less developed countries where they don’t detect the ASDs.
True or false: At elevated altitudes, PVD is more common and occurs at earlier ages.
True
How do you manage ASD?
In infants, diuretics can help relieve breathlessness and you watch to see if it closes on its own.
In older children, adolescents, or adults with significant ASD, treatment is to close the hole.
How can you tell the difference between ASD and PFO?
PFO has a flap that’s moving but ASD is a hole. Can see on echo
PFO doesn’t have overflow of the right heart, the murmurs, or wide S2.
How do you close an ASD?
Surgery or Percutaneous Device Closure
Depends on the size of patient, size of defect, and patient/cardiologist preference.
The Percutaneous procedure is done with a catheter that is positioned across the hole and a disk is deployed on each side of the atrial septum.
