Congenital Heart Abnormalities Flashcards
What is the incidence and etiology of congenital heart disease? What is the most common CHD?
~8/1000 live births (0.8%)
Etiology:
- majority is multifactorial
- genetic (e.g. trisomy 21, single gene, microdeletion)
- environmental (e.g. EtOH, teratogens, maternal diabetes)
Most common is bicuspid aortic valve (1% of the population), then VSD.
What is the segmental approach to evaluating congenital heart anomalies?
- what is the situs of the heart?
- what is the situs of the atria
- are the atrio-ventricular connections concordant or discordant?
- are the ventricle-great vessel connections concordant or discordant and what is their relationship to one another?
What is situs inversus?
SItus inversus: when the position of the organs is the mirror image of what it should be.
What is isomerism?
Isomerism: when you have two of something, instead of one of each (e.g. two righ atria instead of one of each). Can have with atria, ventricles, bronchi, or everything (2 right lungs, 2 right hearts, midline liver…)
What are general (AKA suspicious) features of a congenital heart defect history and exam? What investigations must be done?
History:
- family Hx of CHD, pregnancy complications
- difficulty feeding
- poor growth
- color (cynosis?)
- exercise toletance
Exam
- extra heart sounds, murmurs
- clubbing, cyanosis
- vascular congestion
- work of breathing
Investigations
- EKG
- echo
What is the usual classification of congenital heart defects?
Mixing Lesions:
- left-to-right
- right-to-left
Obstructive lesions
Or cyanotic (the 5 T’s) vs. acyanotic (L–>R shunts, and obstructive)
**These can be alone (simple) or in combination with others (complex)**
Give 4 examples of L–>R shunt and 5 examples of R–>L shunt (5 T’s).
L–> R Shunt:
- ASD
- VSD
- Patent ductus arteriosis
- atriventricular septal (canal) defect
R–> L
- 5 T’s
- Tetrology of Fallot
- TGA
- Tricuspid atresia
- Truncus arteriosis
- Total anomalous pulmonary venous return
- Eisenmenger syndrome (secondary to other defects
What is the difference between an ASD and a patent foramen ovale?
A patent foramen ovale is thought to be present in around 20% of the population, and although it is not anatomically closed, it is functionally closed, so is not classified as a true ASD. ASD can happen at the foramen ovale, but they can also be at other places.
What are the symptoms, physical exam features, CXR/EKG/Echo features, and treatment of ASD?
Symptoms
- usually asymptomatic
- if symptomatic: dyspnea on exertion, fatigue, frequent lower RTI
Physical exam
- right ventricular heave
- fixed S2 splitting
- systolic murmur at pulmonary valve or tricuspid valve (mid-diastolic)
- ASD itself doesn’t produce a murmur
CXR:
- RA and RV enlargment
EKG
- RV hypertrophy
- possible left axis deviation
Echo
- RA and RV enlargement
- may be able to visualize the ASD
Treatment
- percutaneous patch if symptomatic or a significant amount of blood is being shunted
What is the pathophysiology of ASD?
- There are several common locations for this defect, but the most common is near the foramen ovale (called ostum secundum ASD)
- At birth oxygenated blood is pushed from the higher pressure LA into the lower pressure RA during diastole and systole
- This results in a volume overload in the compliant RA, that can eventually develop into severe pulmonary vascular disease (4-5th decade)
- An ASD doesn’t result in pulmonary edema right away because the LA doesn’t back-up into the lungs, and the RV is very compliant and can accomodate extra volume without much change in pressure
What are the symptoms, physical exam features, CXR/EKG/Echo features, and treatment of VSD?
Symptoms
- 90% asymptomatic
- 10%: symptoms of heart failure (FTT, tachypnea,
- frequent lower RTI
Physical exam
- harsh holosystolic murmur
- thrill felt over the defect
- widened S2 splitting
CXR
- cardiomegaly
- enlarged pulmonary arteries
Echo
- can see VSD
EKG
- left ventricular hypertrophy
Treatment
- 50% close on their own
- decision to pursue surgery usually made in the first few months of life
- antibiotic prophylaxis during dental procedures
What is the pathophysiology of a VSD?
- The defect can happen at several sites along the septum.
- After birth blood is shunted from the high pressure LV to the low pressure RV during systole
- This creates volume and pressure overload in the RV, LA and LV
- A VSD has a higher pressure differential than the atria, so it progresses to heart failure more quickly
*
Why does an ASD have fixed S2 splitting and VSD has widened splitting?
The pressure differential is greated between the ventricles, so it is not as affected by the increased venous return during inspiration. In the atria, the pressure differential is pretty small so during inspiration, the venous return pressure diminishes the volume of blood shunted, and during expiration the volume of blood shunted increases (compared to inspiration) resulting in a fixed split
Differences between ASD and VSD
- ASD has fixed splitting, VSD has widened splitting
- No murmur is heard over an ASD because the pressure difference is not high enough
- A thrill is often felt over a VSD because the pressure differential is greater
- Usually see RVH with ASD and LVH with VSD
- VSD has more risk for infective endocarditis.
What is the natural course of ASD?
- usually clinically quiet
- compromises CO, increases pulmonary work
- dynamics of shunt chnage with age, often presents in 30-50’s
- Presents with one or more of:
- arrhythmia (stertching of the conduction system)
- RV dysfunction
- Paradoxical emboli
- Pulmonary vascular disease (rarely!)