What is the treatment for a left to right shunt?

Treatment of Left-to-Right Shunts

Percutaneous device closure or surgical repair is the definitive treatment for significant left-to-right shunts causing physiological sequelae, provided that pulmonary artery systolic pressure is less than 50% of systemic pressure and pulmonary vascular resistance is less than one-third systemic. 1

Evaluation and Diagnosis

Before determining treatment, proper evaluation is essential:

• Hemodynamic assessment: Measure shunt magnitude (Qp:Qs ratio), pulmonary artery pressures, and pulmonary vascular resistance
• Imaging: Use echocardiography, CMR, or CTA to define anatomy and shunt direction
• Oxygen saturation: Perform pulse oximetry at rest and with ambulation to detect exercise-induced desaturation

Treatment Algorithm Based on Shunt Type

1. Atrial Septal Defect (ASD)

• Secundum ASD:

  • With Qp:Qs ≥1.5:1, right heart enlargement, PA systolic pressure <50% systemic, and PVR <1/3 systemic: Transcatheter device closure 1, 2
  • If unsuitable anatomy for device: Surgical closure 1

• Primum ASD, Sinus Venosus, or Coronary Sinus Defect:

  • With Qp:Qs ≥1.5:1, right heart enlargement, PA systolic pressure <50% systemic, and PVR <1/3 systemic: Surgical repair 1

2. Ventricular Septal Defect (VSD)

• With Qp:Qs ≥1.5:1, PA systolic pressure <50% systemic, and PVR <1/3 systemic:
  • Muscular or perimembranous VSD: Transcatheter device closure 1
  • Other VSD types: Surgical repair 1

3. Patent Ductus Arteriosus (PDA)

• Moderate-sized or large PDA with left-to-right shunt causing:
  • Congestive heart failure, pulmonary overcirculation, or left atrial/ventricular enlargement: Transcatheter PDA occlusion 1
  • Small PDA with audible murmur: Transcatheter PDA occlusion is reasonable 1

Special Considerations Based on Pulmonary Pressures

1. Normal pulmonary pressures (PA systolic pressure <50% systemic, PVR <1/3 systemic):

   • Definitive closure recommended for symptomatic patients or those with cardiac chamber enlargement 1

2. Borderline elevated pulmonary pressures (PA systolic pressure ≥50% systemic, PVR >1/3 but <2/3 systemic):

   • Closure may be considered but requires careful evaluation 1, 2
   • Consultation with ACHD and pulmonary hypertension specialists recommended 1

3. Severe pulmonary hypertension (PA systolic pressure >2/3 systemic, PVR >2/3 systemic, or right-to-left shunting):

   • Closure contraindicated due to high morbidity and mortality 1
   • Consider pulmonary vasodilator therapy first 1

Important Clinical Pitfalls

1. Eisenmenger syndrome: Never close a shunt in patients with severe pulmonary hypertension and right-to-left shunting as this carries high mortality 1

2. Diastolic dysfunction: In older adults, carefully evaluate for left atrial hypertension from diastolic dysfunction, as ASD closure could worsen symptoms by preventing right atrial decompression 1

3. Bidirectional shunting: In patients with bidirectional shunting, careful hemodynamic assessment with cardiac catheterization is essential before deciding on closure 1

4. Associated lesions: Evaluate for other cardiac abnormalities that may affect treatment decisions (e.g., aortic valve prolapse with VSD, tricuspid regurgitation with ASD) 1

5. Pulmonary vascular disease: Some patients with elevated but not severe pulmonary pressures may benefit from pulmonary vasodilator therapy before considering shunt closure 1

By following this algorithm and considering these special circumstances, clinicians can optimize outcomes for patients with left-to-right shunts, reducing morbidity and mortality while improving quality of life.