What is the incidence and etiology of congenital heart disease? What is the most common CHD?
~8/1000 live births (0.8%)
- 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?
- family Hx of CHD, pregnancy complications
- difficulty feeding
- poor growth
- color (cynosis?)
- exercise toletance
- extra heart sounds, murmurs
- clubbing, cyanosis
- vascular congestion
- work of breathing
What is the usual classification of congenital heart defects?
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:
- Patent ductus arteriosis
- atriventricular septal (canal) defect
- Tetrology of Fallot
- 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?
- usually asymptomatic
- if symptomatic: dyspnea on exertion, fatigue, frequent lower RTI
- right ventricular heave
- fixed S2 splitting
- systolic murmur at pulmonary valve or tricuspid valve (mid-diastolic)
- ASD itself doesn't produce a murmur
- RA and RV enlargment
- RV hypertrophy
- possible left axis deviation
- RA and RV enlargement
- may be able to visualize the ASD
- 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?
- 90% asymptomatic
- 10%: symptoms of heart failure (FTT, tachypnea,
- frequent lower RTI
- harsh holosystolic murmur
- thrill felt over the defect
- widened S2 splitting
- enlarged pulmonary arteries
- can see VSD
- left ventricular hypertrophy
- 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)
Pulmonary vascular disease (rarely!)
- arrhythmia (stertching of the conduction system)
- RV dysfunction
- Paradoxical emboli
- Pulmonary vascular disease (rarely!)
What is the natural history of VSD?
As always, depends on the size of the defect. Most small defects close spontaneously.
For large VSD:
- CHF in infancy (brings FTT, infection risk)
- Pulmonary vascular disease
- usually repaired early (< 6 mo)
Define Eisenmenger's syndrome
Eisenmenger syndrome is a general term applied to pulmonary hypertension and shunt reversal in the presence of a congenital defect, including VSD, ostium primum ASD, AV canal defect, aortopulmonary window, or PDA.
What is the pathophysiology of patent ductus arteriosis?
blood flows from the aorta into the pulmonary circulation
LA and LV become volume overloaded and dilate
left-sided heart failure can occur
Eisenmenger syndrome can occur
What are the symptoms, physical exam features, CXR/EKG/Echo features, and treatment of PDA?
- small lesions are asymptomatic (but should be closed anyways due to rick of endoarterirtis)
- large lesions develop CHF symptoms (poor feeding, FTT, tachypnea, tachycardia, frequent lower RTI)
- continuous machine-like murmur, crescendo-decrescendo
- cardiomegaly (LA and LV)
- pulmonary markings
- can see lesion, and how much blood is flowing through it
- pharmacological closure (prostaglandin synthesis inhibitors)
Natural course of PDA
Before surgical intervention, most died before 40 yrs, and many got infective endocarditis
Now 99% of surgery is successful
Give 2 examples of obstructive lesions? Do obstructive lesions lead to cyanosis?Do they lead to pressure or volume overload?
coarctation of the aorta
**not in isolation because there is no mixing of oxy/deoxy blood
**they cause pressure overload
What is the pathophysiology of aortic coarctation?
This is when there is a constriction in the aorta. There are 2 kinds: preductal (2%) and postductal (98%). (Duct= ductus arteriosis)
- pressure overload on upstream aorta, valve, LA and LV
- chronic hypertension upstream of kesion
- LVH--> anginal pains are possible
What are the symptoms, physical exam features, CXR/EKG/Echo features, and treatment of aortic coarctation?
- preductal or sever postductal found at birth
- otherwise is often asymptomatic
- cyanosis in lower limbs (if the ductus arteriosis remains open)
- upper limb hypertension
- weak, delayed femoral pulses
- can see constriction
- if severe neonate, give PG to keep DA open
- surgical repair (stent, reanastomsing)
Are the ventricles of neonates relatively more or less compliant than adult ventricles? Why do infants become cyanotic easily?
The ventricles are less compliant, therefore the neonate compensates for low cardiac output mainly by increasing heart rate
Neonates are transiently polycythemic because blood from the placenta is now restricted to the neonate after birth. This means a lower percentage of cells need to be deoxy to see cyanosis.
Features of Tetrology of Fallot
There are four primary components of TOF:
- right ventricular outflow obstruction (created by valvular or supravalvular pulmonic stenosis)
- a large VSD
- an overriding aorta
- right ventricular hypertrophy.
What must accompany a TGA in order for the neonate to survive?
They must have a mixing lesion of some kind, usually VSD or ASD.
What are the adult remnants of the umbilical vein and the ductus venosus?
Umbilical vein--> ligamentum teres (round ligament of the liver)
Ductus venosus--> liganmentum venosum
Are the "cardiac nerves" sympathetic or parasympathetic?
How many lesions are required for a R--> L shunt?
Need 2 lesions
- one connection between R and L side (e.g. ASD or VSD)
- something that makes it hard to pump blood into the pulmonary circulation (e.g. pulmonary stenosis)
Oxygen Saturation Measurements: superior vena cava 70%, right atrium 70%, right ventricle 70 %, pulmonary artery 95%, pulmonary vein 99%, left atrium 99%, left ventricle 99%, aorta 75%
What kind of defect is this?
transposition of the great arteries
Atrioventricular canal defect is commonly associated with:
What is truncus arteriosis?
What is hypoplastic left heart syndrome?
A spectrum of abnormally small left-sided heart structures.