Atrial Septal Defect (ASD)

Cardiovascular Disorders

• Two main categories include congenital heart disease (CHD), which are anatomical abnormalities at birth, and acquired heart disorders, which develop after birth.
• CHD occurs in 5-8 per 1000 live births with 2-3 per 1000 infants being symptomatic within the first year.
• Development of defects occur primarily in the first 8 weeks of gestation as a result of genetic and environmental factors.
• Classification is based on pathophysiology and hemodynamics, not only cyanosis.

Atrial Septal Defect (ASD)

• Characterized by an abnormal opening between the atria, resulting in a left-to-right shunt.
• 30-50% of ASD cases occur with other congenital heart defects, and 5-10% present as an isolated defect.
• Large ASDs may cause dyspnea, fatigue, poor growth, a soft systolic murmur in the pulmonic area, and potential congestive heart failure (CHF).
• Echocardiogram shows a dilated right ventricle.
• Chest X-ray/ECG show defects when the defect is large.
• Small ASDs close spontaneously in about 4 years.
• Device closure with an Amplatzer Septal Occluder happens via cardiac catheterization.
  • An Aspirin regimen of 81 mg happens daily for 6 months post-procedure.
• Surgery includes a pericardial or Dacron patch if CHF is present.
  • Open repair with cardiopulmonary bypass happens before school age.
• Post-op arrhythmias is a potential complication.

Ventricular Septal Defect (VSD)

• An opening between the right and left ventricles that increases pulmonary blood flow, resulting in a left-to-right shunt.
• It is the most common CHD, accounting for 15-20% of cases, and can appear alone or with other defects.
• Small VSDs are often asymptomatic.
• Large/moderate VSDs can lead to CHF, poor growth, exercise intolerance, pulmonary infections, pulmonary hypertension, a systolic murmur (3rd/4th LICS, sternal border), and a possible thrill.
• Chest X-rays provide little information for small VSDs.
  • Large VSDs show an enlarged heart, pulmonary markings, and ventricular hypertrophy.
• Echocardiograms can determine the size and location of VSDs.
• Small VSDs commonly close spontaneously within 6-12 months.
• Medical management is an option for asymptomatic or mild cases.
• Surgical closure is opted for if:
  • One year has passed unless CHF is unmanageable, or within 6 months if severe.
  • Device closure is possible unless near valves.
  • Pulmonary artery banding for multiple or complex VSDs.
  • Dacron patches are used for large VSDs and suture repairs are used for small VSDs.
• Procedure includes cardiopulmonary bypass and an approach is made through the right atrium to the tricuspid valve.
• Complications include residual VSD, conduction issues like RBBB/heart block, arrhythmias, and the possible need for a pacemaker.
• There is a high risk in the first 2 months of life, with good recovery and catch-up growth being common.

Patent Ductus Arteriosus (PDA)

• Failure of the ductus arteriosus (connecting the aorta and pulmonary artery) to close after birth, leading to a left-to-right shunt.
• It is common among preterm infants with respiratory distress or hypoxemia, with an incidence of 5-10% of CHD cases.
• Mild instances are asymptomatic.
• Moderate to large PDAs show dyspnea, tachypnea, tachycardia, full/bounding pulses, widened pulse pressure, hypotension, CHF, poor growth, hepatomegaly, a continuous "machinery" murmur, and frequent respiratory infections.
• Clinical findings of an LV hypertrophy are seen through a Chest X-ray/ECG.
• Echocardiogram visualizes PDA and blood flow.
• Medical intervention includes IV Indomethacin/Ibuprofen only for preterm infants, not for those with CHF or term infants.
• Nonsurgical intervention involves transcatheter closure (obstructive device or coils).
• A thoracotomy and thoracoscopy are possible options to apply (ligature and clipping).
• Complications are rare if treated early; <1% mortality unless very premature.

Tetralogy of Fallot (TOF)

• Cyanotic heart defects composed of 4 anatomical abnormalities: Pulmonary Stenosis (PS), Right Ventricular Hypertrophy, Ventricular Septal Defect (VSD), and Overriding Aorta.
• Accounts for 5-10% of congenital heart disease.
• Blood from both ventricles mixes → unoxygenated blood enters systemic circulation.
• Shunting direction depends on vascular resistance:
  • Right-to-left shunt: pulmonary resistance > systemic resistance → cyanosis.
  • Left-to-right shunt: systemic resistance > pulmonary resistance.
• Clinical presentation:
  • Newborns: cyanosis worsens as ductus arteriosus closes.
  • Older infants/children: cyanosis, tachypnea, hypoxic (tet) spells, polycythemia, clubbing, poor growth, squatting/knee–chest position.
• Squatting/knee-chest position improves oxygenation.
• Murmur occurs systolic in pulmonic area, may have thrill.
• Boot-shaped heart, decreased pulmonary vascular markings show on chest x-ray.
• Shows RV hypertrophy on ECG.
• Echo confirms all 4 defects.
• Elevated Hct/Hb, prolonged clotting time, and iron deficiency show in labs.
• Palliative action includes a Modified Blalock-Taussig shunt if not ready for repair.
• Surgical options for repair include:
  • VSD closure
  • Resection of stenosis
  • Transannular patch may cause pulmonary valve incompetence
  • Median sternotomy with cardiopulmonary bypass
• Mortality rate is at <3%.
• Postoperative HF, arrhythmias, and rare surgical heart block are potential complications.