MHD: Congenital Heart Disease Flashcards
What is meant by “the complex” in congenital heart diseases?
When a group of abnormalities tend to be associated and contribute together to altered economy of the heart
What is a shunt?
A transfer of blood from one side of the circulation to the other through an abnormal pathway (Left to right, right to left)
What is the major shunt associated with the atria?
Atrial septal defect (ASD)
What is the major shunt associated with the ventricles?
Ventricular septal defect (VSD)
What is the major shunt associated with the ducts?
Patent ductus arteriosus (PDA)
What are the types of atrial septal defect?
Fossa ovalis (Secundum type) Ostium primum type Sinus venosus (proximal type) Coronary sinus type
Describe the blood flow through an atrial septal defect
Left to right shunt forms because the pressure in the left atrium is slightly higher than the right atrium and the right ventricle has a much larger compliance.
Result: volume hypertrophy of RA and RV, increased pulmonary flow
Do ASDs typically cause cyanosis and hypoxemia?
No. L to R shunt moves some oxygenated blood back to pulmonary, but does not typically reverse.
What is the most common type of VSD?
Subaortic: defect located just beneath the aortic valve through the membranous septum
Describe the blood flow through a ventricular septal defect
Left to right shunt leads to volume hypertrophy of the left atrium, left ventricle, right ventricle and enlargement of the pulmonic orifice
What is the natural history of VSDs?
Small defects can be asymptomatic, resolve in first few years of life.
VSDs increase risk for infective endocarditis
What is Eisenmenger syndrome?
Reversal of shunt direction due to changes in vascular resistance
Ex: as defect progresses, pulmonary pressure can raise above the left sided pressure, leading to R to L shunting
Describe the blood flow through a patent ductus arteriosus
Left to right shunt through the ductus arteriosus leads to volume hypertrophy of the LA and LV
Which congenital defects increase pulmonary flow?
L to R shunts
ASD, VSD, PDA
What are the reasons for the development of pulmonary hypertension in congenital heart defects?
Flow beyond the distensibility of the lung vasculature
Vasoconstriction of pulmonary vascular bed
Secondary pathologic changes in lung
Which shunts are most likely to involve pulmonary hypertension
VSD > PDA > ASD
Congenital pulmonary stenosis results in hypertrophy of what chamber?
Right ventricle
Congenital aortic stenosis results in hypertrophy of what chamber?
Left ventricle
What are the two types of supravalvular aortic stenosis?
Subaortic stenosis: involves fibroelastic tissue
Muscular: hypertrophic cardiomyopathy
What is coarctation of the aorta?
Narrowing of the transverse aortic arch
What is tetralogy of fallot?
A developmental defect leading to 4 anomalies:
1) Infundibular pulmonary stenosis
2) Right ventricular hypertrophy
3) VSD
4) Overriding aorta (receives blood from RV and LV)
What is the infundibulum?
The outflow tract of the right ventricle
What is the characteristic shape of the VSD in tetralogy of fallot?
U shaped
What are the two types of tetralogy of fallot?
Cyanotic (more common)
Acyanotic
Describe the effects of cyanotic tetralogy of fallot
Pressure hypertrophy of RA and RV due to pulmonary obstruction. LA and LV are typically smaller than normal.
Prominent R to L shunt leads to cyanosis
Describe the effects of acyanotic tetrology of fallot
L to R shunt at ventricles, so no cyanosis
Hypertrophy of RV, RA, LA and LV
What happens in Transposition of the Great Arteries?
Aorta originating from RV, pulmonary artery from LV
2 separate circuits in parallel as opposed to the normal in-series arrangement, oxygenation of systemic blood does not occur
Why doesn’t TGA cause death during fetal development or early after birth?
The physiologic shunts (foramen ovale and ductus arteriosus) allow mixing between the two circuits, so some oxygenated blood is able to reach system.
These must remain open for the defect to be compatible with life.
