Left-Right Shunt Congenital Heart Disease Flashcards
Incidence of L-R shunt
8/1000 live births (about 1%)
What is the risk of a child with a family history (parents) to develop the disease?
10%
What is the risk of a child with a family history (siblings) to develop the disease?
2%
What medications increase incidence of CHD?
Anticonvulsants, lithium, warfarin, alcohol.
What diseases increase risk of CHD?
DMI, Lupus (SLE), rubella, mumps, Coxsackie.
What risk factors in the baby correlate with CHD?
Trisomy 21, 13 and 18, Turner syndrome.
Typed of congenital heart disease
- L-R shunt (pink babies), 2. R-L shunt (blue babies), 3. Obstructive lesions, 4. Arrhythmias
When can CHD be detected on a fetal echo?
20 weeks
Types of left to right shunts?
- Ventricular Septal Defect (VSD), 2. Atrial septal Defect (ASD) 3. Patent Ductus Arteriosus (PDA) 4. Atrio Ventricular Septal Defects (AV canal)
How does pulmonary vascular resistance change between pregnancy and birth?
Very high resistance during pregnancy (lungs not inflated). Sharp dramatic drop during first hours after first cry. Continuous drop to normal levels during 4-6 weeks of life.
What is the perimembranous region?
Part of muscular intraventricular septum adjacent to membranous septum.
What does the endocardial cushion produce?
4 projections like an amoeba: 1. Membranous intraventricular septum, 2. Atroventricular septum, 3. Anterior leaflet of mitral valve, 4. Septal leaflet of TCV.
If a surgeon is told that a patient has a perimembranous outlet VSD, where does he look?
Coming from RA to look anteriorly at the level of the pulmonary artery.
What components influence the severity of the VSD shunt?
VSD size and Pulmonary resistance
How is the VSD size determined?
Compared to baby’s aorta. 60% is large.
What is the clinical presentation of a small VSD?
Pansystolic (the smaller the stronger) murmur or no murmur. No problems until after 1st year. Harsh noise but no symptoms.
What is the prognosis for a small VSD?
In 60-80% spontaneous closure before 1yo. No treatment. Complications: endocarditis (SBE prophylaxis recommended).
Clinical presentation of moderate and large VSD?
Pulmonary resistance is a factor: illness at 4-6 weeks after PR drops. Pressure gradient: L-R shunt. Pansystolic murmur at LLSB or middiastolic murmur at apex. 1st thing seen in echo is increased LA pressure and size because pulmonary veins have a lot of flow. Increasing pressure in LA: backwards flow in pulnmonary veins, alveoli backflow, pulmonary edema- stress situation: tachycardia, tachypnea, sweating (forehead), enlarged liver, difficulty feeding. Slowly, not overnight. CXR: cardiomegaly, enlarge PA, pulmonary edema.
Murmur in moderate and large VSD
Mitral valve formed by fibrous analous so movement is limited A lot of volume goes through the same size mitral valve creates turbulence and a murmur: 2 murmurs: 1. through VSD in L-R ventricle-pansystolic; and 2. diastolic murmur when extra flow passes from LA to LV through undilated mitral valve.
Treatment of moderate/large VSD
Frequent feedings with added calories. Medications.
What medications treat VSD?
- Preload: diuretics. 2. Contractility: inotropes (Digoxin), 3. Afterload (mercaptopurine)
Types of surgical treatment of VSD
Palliative (Pulmonary Artery Banding-PAB) or Curative (Primary repair)
Pulmonary artery banding (PAB)
Small surgery, closed chest. Enter pulmonary artery through axila. Place band around pulmonary trunk and decrease diameter, increasing resistance. Right side has to create more pressure and shunt decreases.