Congenital Heart Disease 2 Flashcards
What is a VSD?
Ventricular septal defect.
What % of all congenital heart defects is VSD?
20%
How many fetuses have VSDs?
About 5%. Although there is a high incidence of spontaneous closure
True or False: VSDs are often seen in combination with other complex congenital heart lesions
True
When does Ventricular septation occur?
Post loop stage (day 28-42)
How many endocardial cushions form to make the ventricular septum?
4 (superior, inferior, right, and left)
Which 2 endocardial cushions fuse to create the left atrioventricular canal and right atrioventricular canal?
Superior and inferior endocardial cushions.
What is the membranous septum; interventricular portion?
The membranous portion of the interventricular septum is the most common area of VSD development. This is called a perimembranous VSD
What is the most common type of VSD?
Perimembranous VSD. deficiency or lack of the membranous portion of the interventricular septum.
What does the superior endocardial cushion turn into?
- The left surface of the outlet portion of the interventricular septum.
- Part of the mitral valve
What does the inferior endocardial cushion turn into?
- The inlet portion of the interventricular septum
- Membranous portion of the interventricular septum
- Parts of the tricuspid and mitral valves
What does the right endocardial cushion turn into?
Parts of the tricuspid valve
What does the left endocardial cushion turn into?
Posterior leaflet of the mitral valve.
Of the 4 endocardial cushions, which one is the perimembranous VSD a defect in?
Inferior Endocardial Cushion
What % of all VSDs is the perimembranous VSD?
70%
What is a muscular VSD?
10% of all VSDs. They form in any part of the muscular part of the septum (in contrast the membranous part).
Muscular VSDs are rarely and issue and often close on their own while perimembranous often do not.
What is considered a large defect for VSDs?
When the defect diameter is the same as or greater than the aortic orifice.
Explain the shunt direction and magnitude of VSD and ASD
For ASD, the blood in the LA is deciding whether to go through the ASD to the RA or to the LV. So, the compliance of the ventricles makes the difference.
For VSD, the blood in the LV is deciding whether to go through the VSD or through the aorta. So, the difference between systemic and pulmonary vascular resistances makes the difference.
These are still both left-to-right shunts (typically) because left is greater pressure than right.
Also, keep in mind that obstructive lesions (e.g. pulmonary or aortic valve stenosis) will also influence shunt magnitude and direction
In VSD, end-diastolic volume is increased in which chamber of the heart?
LV.
WTF? shouldn’t a ventricular septum hole make it so blood leaks out of the LV for less end-diastolic volume? No. Normally, all of the blood in the LV leaves through the aorta. But in VS, some of the blood that’s supposed to leave goes through the VSD to the RV and through the lungs back to the LV. The LV gets increased end-diastolic volume. The increased end-diastolic volume increases the muscle fiber length in the LV which increases contractility which results in an increased LV output. (This does not mean increased CO output… because the LV contractility is increased and LV output is increased but some of that “output” is back into the RV)
What are VSD symptoms after birth?
Typically asymptomatic until PVR starts to fall, even if the defect is large (takes a few days to fall). The fall in PVR is delayed at elevated altitudes.
In large VSDs
- there can be respiratory distress and diaphoresis, especially when feeding
- failure to thrive
In small VSDs
Tachypnea and diaphoresis are usually mild or absent.
What are the physical exam findings for a large VSD?
Active precordium
Accentuated second heart sound (from pulmonary HTN)
2-3/6 harsh, holosystolic murmur loudest at LLSB, but can usually be heard throughout the chest
Diastolic murmur secondary to increased flow across the mitral valve.
What are the physical exam findings for small VSDs?
Precordial activity is usually normal
Normal second heart sound
2-4/6 early systolic murmur
No diastolic murmur
What does the murmur volume mean?
A smaller VSD or a VSD starting to close will have a louder sound. Louder is often a good sign in VSDs.
Louder murmur could also mean a lower pulmonary vascular resistance. (which is also a good thing bc you aren’t having pulmonary HTN which happens in larger VSDs)
A murmur that goes away is not always a good thing. It may mean that the VSD has closed but it can also mean that the VSD is large with equalization of RV and LV pressure and elevation in pulmonary vascular resistance (pulmonary HTN)
What is the diagnostic tool of choice for VSDs?
Echo (gold standard)
Defines location and number of defects
Can estimate magnitude of shunt
Can identify associated lesions or complicating factors such as aortic insufficiency
– additional –
ECG
Normal in small defects
Right axis deviation and increase in RV and LV voltages (combined hypertrophy)
Radiograph
Increased lung vascularity. Enlarged main pulmonary artery. Cardiomegaly.
What is non-surgical management of VSD?
Symptom based management in infancy.
Diuretics can prevent pulmonary edema. Digoxin and afterload reduction can help (ACE inhibitors)
Small defects are just observed and hopefully they close on their own.
What are indications for surgical closure of a VSD? (3)
- Development of pulmonary vascular changes in the setting of a large defect.
- Persistent symptoms of poor growth despite medical therapy.
- Development of secondary complications (aortic insufficiency, double-chambered RV, etc)
True or false: Large VSDs can increase in size over time.
False. Many large defects actually decrease in size. However, large defects need to be treated because if they are left untreated it can be devastating.
What is Eisenmenger’s Syndrome?
Eisenmenger’s syndrome happens in large left to right shunts (more common in VSD but can happen in ASD).
A large left to right shunt causes an increase of pulmonary blood flow which results in a muscularization of pulmonary arterioles creating pulmonary HTN and increased right ventricular pressure. As this progresses, there can be a shunt reversal and now the blood is going from right to left. The blood going from RV to LV is deoxygenated and results in cyanosis and clubbing.
How do you fix eisenmenger’s syndrome?
It’s irreversible. You can’t close the VSD because these patients are relying on that hole to get blood out of the RV since the pulmonary HTN is so high.
This results in death or can maybe be helped by a heart/lung transplant.
What is Tetralogy of Fallot?
ToF is a cyanotic heart disease complex
- RV outflow tract obstruction
- RV hypertrophy
- Extraposition of the aorta (aorta overrides the VSD)
- VSD
Of all congenital heart defects, what % is ToF?
15%