Congenital Heart Disease 1 Flashcards
goals of fetal circulation
- preferential streaming of oxygenated blood to the myocardium and brain (O2-rich blood comes from the placenta, not the lungs)
- recycling of de-oxygenated blood through the placenta (via the descending aorta)
pathway of oxygenated blood flow in fetal circulation
- oxygenated blood from the placenta enters into the umbilical vein into the ductus venosus
- ductus venosus sends some of the blood into hepatic circulation and the rest enters the IVC
- oxygenated blood enters the right atrium and the Eustachian valve directs blood through the foramen ovale into the left atrium
- blood passes from the left atrium into the left ventricle and is sent out through the aorta into systemic circulation, particularly to the brain and heart muscle
pathway of deoxygenated blood flow in fetal circulation
- deoxygenated blood enters the right atrium primarily from the SVC and it is shunted through the tricuspid valve into the right ventricle
- right ventricle pumps blood into main pulmonary artery, where some goes to the lungs, but the majority passes through the ductus arteriosus to dump directly into the descending aorta
- the umbilical arteries carry deoxygenated blood from the descending aorta back to the placenta
transition from fetal circulation to newborn circulation
*before birth, pulmonary resistance is higher than systemic
*hypertrophied medial layer of pulmonary arterioles keeps blood out of the lungs
*on the first breath, pulmonary vascular resistance decreases
*pulmonary bed is fully “relaxed” by 4-8 weeks
patent foramen ovale (PFO)
*foramen ovale is necessary in the fetus to promote mixing of oxygenated & deoxygenated blood
*closes when septum primum & septum secundum close, usually by age 2
*25-30% of people have a residual PFO in adulthood
*can be a source of cryptogenic stroke
congenital heart disease - overview & epidemiology
*present in 8/1000 live births
*most common congenital defect
*many ways to classify, including:
-acyanotic shunt lesions
-acyanotic obstructive lesions
-cyanotic defects
-single ventricle lesions
most common congenital heart defects
most common (overall):
*ventricular septal defect (VSD): 25-30% of heart defects
most common CYANOTIC heart defects:
*Tetralogy of Fallot
*transposition of great arteries
acyanotic congenital heart defects: shunt lesions (left-to-right) - examples
*atrial septal defects (ASD)
*ventricular septal defects (VSD)
*patent ductus arteriosus (PDA)
*atrioventricular septal defect (AV canal)
acyanotic congenital heart defects: obstructive lesions - examples
*pulmonic stenosis (PS)
*aortic stenosis (AS)
*coarctation of the aorta
atrial septal defects (ASD) - 3 major types
- ostium secondum ASD:
-most common
-region of foramen ovale - ostium primum ASD:
-more inferior
-form of AV septal defect - sinus venosus ASD:
-least common
-high in atrial septum
-usually associated with anaomalous pulmonary veins
atrial septal defects (ASD) - overview
*defect in interatrial septum
*ASD is a LEFT-TO-RIGHT SHUNT
*ostium secundum defects are most common
atrial septal defects (ASD) - symptoms & diagnostic criteria
*most are asymptomatic
*essentials of diagnosis:
-WIDE, FIXED SPLIT S2
-right ventricular heave
-“pulmonary stenosis” or “tricuspid stenosis” murmur
-cardiac enlargement on CXR
atrial septal defects (ASD) - management
*no medical management necessary (asymptomatic)
*closed effectively after 3-4 years if needed to prevent pulmonary vascular changes
*catheter closure or surgery
ventricular septal defects (VSD) - overview
*most common congenital heart defect, accounting for almost 30% of congenital heart disease
*2 types: muscular vs. membranous
*clinical effect depends on size of defect
clinical features of large ventricular septal defects (VSD)
*“slow eater, fast breather”
*findings of heart failure:
-failure to thrive
-mild-plus respiratory distress
-lung findings
-enlarged liver
*quieter murmur (less resistance to flow compared to smaller VSD)
clinical features of small ventricular septal defects (VSD)
*asymptomatic
*thriving children with normal breathing pattern
*loud, harsh, high-pitched holosystolic murmurs
ventricular septal defects (VSD) - treatment
*small defects - no therapy indicated (often close spontaneously)
*moderate defects - medical management:
-treat symptoms of heart failure
-diuretics
-increased caloric density
-might close spontaneously
*large defects - medical management until 3-6 months of age, then patch closure in the OR
which side of the heart becomes enlarged in ASDs and VSDs?
*in ASDs, the right side of the heart generally becomes enlarged
*in VSDs, the left side of the heart generally becomes enlarged
systolic murmurs - general causes
- forward flow through aortic or pulmonary valve
-physiologic: anemia, bradycardia, fever, hyperthyroidism
-pathologic: aortic stenosis, pulmonary stenosis - backward flow through mitral valve (mitral or tricuspid regurgitation
- flow across a VSD
- innocent flow within the cavity (Still’s)
systolic ejection murmurs vs. holosystolic murmurs
*aortic stenosis and pulmonary stenosis are systolic ejection murmurs
-no murmur is heard during isovolumetric contraction because no blood is crossing the valve yet
*VSD and mitral regurgitation are holosytolic murmurs
-you can hear the murmur during the period of isovolumetric contraction
patent ductus arteriosus (PDA) - overview
*persistence of normal fetal vessel joining the pulmonary artery to the aorta
*in normal term infants, ductus arteriosus closes spontaneously at 3-5 days of age
*when PDA persists, blood starts to shunt from left-to-right (from aorta to pulmonary artery)
patent ductus arteriosus (PDA) - clinical findings
*characteristically has a rough “machinery” murmur heard below the left clavicle
*murmur occurs throughout the cardiac cycle because blood is flowing continuously
*occasionally a diastolic rumble at the apex
*widened pulse pressure (difference in pressure between systolic and diastolic)
*bounding pulses
patent ductus arteriosus (PDA) - treatment
*medical treatment: PGE inhibitors (indomethacin, ibuprofen, acetaminophen)
*surgical treatment: duct ligation via a thoracotomy
*catheter based treatment: Piccolo device
