Single Ventricle Congenital Heart Disease

Aka: Single Ventricle Congenital Heart Disease, Single Ventricle Defect, Single Ventricle Defect Management, Norwood Procedure, Post-Norwood Decompensation, Interstage Decompensation of Congenital Heart Disease, Bidirectional Glenn Procedure, Fontan Procedure, Blalock-Taussig Shunt, Sano Shunt

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II. Causes

  1. Hypoplastic Left Heart Syndrome (HLHS)
  2. Tricuspid Atresia
  3. Mitral Valve Atresia
  4. Ebstein Anomaly
  5. Double Outlet Right Ventricle (DORV)
  6. Pulmonary Atresia
  7. Atrioventricular Canal Defect

III. Management: General

  1. Staged procedures aim to direct the single ventricle for systemic circulation and passive flow to the pulmonary circuit
  2. In some cases, Heart Transplantation is an option

IV. Management: Surgery Stage 1 (Norwood Procedure, Birth)

  1. Performed shortly after birth
  2. Key goal is to allow single ventricle to provide both systemic and pulmonary circulation
    1. Establishes permanent flow between right ventricle and aorta
  3. High mortality in the first 24-48 hours of procedure
  4. Three Stage Procedure (Very complex repair)
    1. Shunt replaces Patent Ductus Arteriosus
      1. Blalock-Taussig Shunt (subclavian artery to pulmonary artery) OR
      2. Sano Shunt (right ventricle to pulmonary artery)
    2. Atrial Septoplasty creates an Atrial Septal Defect
    3. Neo-Aorta created

V. Management: Post-Operative Stage 1 (Interstage Period, Post-Norwood, age <6 months)

  1. Newborns discharged after Norwood Procedure, awaiting Stage 2 repair at 4-6 months
    1. Delay allows for needed growth
  2. High risk period for decompensation due to tenuous cardiovascular physiology
    1. Mortality 10% during this period
  3. Decompensation Causes
    1. At risk for severe decompensation even with mild Viral Infections
    2. RSV BronchiolitisHypoxemia
    3. Gastroenteritis with Dehydration
  4. Presentations
    1. Increased Systemic Vascular Resistance (cold, cyanotic digits)
    2. Metabolic Acidosis
    3. Shunt thrombosis
      1. High mortality risk and requires immediate management
      2. Dehydration is a risk for shunt thrombosis
      3. Patent shunt normally creates a machinery murmur
        1. Consider shunt thrombosis if no murmur is heard
      4. Start IV Heparin if shunt thrombosis is suspected
  5. Evaluation and Management
    1. Emergent pediatric cardiology or cardiothoracic surgery Consultation
    2. Admit or observe all children even with mild illness in this stage
    3. Avoid excessive Supplemental Oxygen to maintain systemic perfusion
      1. Oxygen results in vasodilation of pulmonary vessels and shunts flow away from systemic circulation
        1. Excessive oxygen risks serious Hypotension, shock or death
      2. Keep Oxygen Saturation goal 75-85% (normal O2 Sat following Norwood)
        1. Ask parents the range of their child's Oxygen Saturation
    4. Preload dependent (excessive intrathoracic pressure decreases venous return)
      1. Consider small fluid Normal Saline bolus trials (5-10 ml/kg)
      2. Monitor IVC Ultrasound for Volume Status
      3. Vasopressors (if needed)
        1. Norepinephrine and Epinephrine are preferred
        2. Phenylephrine may be used to temporize
    5. Consider causes of Hypoxemia <75% Oxygen Saturation
      1. Consider shunting
      2. Trial low FIO2 by Nasal Cannula
      3. Evaluate Blood Pressure and other markers of perfusion
      4. Obtain Chest XRay
      5. Obtain Point Of Care Cardiac Ultrasound (e.g. Pericardial Effusion, Lung Ultrasound, Cardiac Function)
      6. Consider Brain Natriuretic Peptide (BNP)
    6. Pulmonary-Systemic Flow Ratio (Qp/Qs) evaluates persistently decreased perfusion:
      1. Normal Pulmonary (Qp, estimated at 25) to Systemic (Qs) ratio is 1:1
      2. Qs = 100 - Oxygen Saturation
      3. Qs <25 suggests need for either small fluid bolus trial or Vasopressors

VI. Management: Surgery Stage 2 (Glenn Procedure, age 4-6 months)

  1. Performed at age 4-6 months
  2. Bidirectional Glenn Procedure
    1. Partial Caval Anastomosis
      1. Superior vena cava is connected to pulmonary artery
      2. Allows for passive circulation to lung
    2. Shunt removed
      1. Blalock-Taussig or Sano Shunt placed with Norwood Procedure is removed
  3. Post-operative changes
    1. Cardiopulmonary physiology improves and hemodynamic status is more stable than Post-Norwood
    2. Oxygen Saturation improves to 90%

VII. Management: Surgery Stage 3 (Fontan Procedure, ages 18-36 months)

  1. Performed between ages 18 to 36 months
  2. Fontan Procedure
    1. Inferior Vena Cava (IVC) connected to pulmonary artery (PA)
    2. Fenestration may be placed between IVC and PA to regulate flow and prevent pulmonary overload
  3. Post-operative changes
    1. Cardiopulmonary status stabilizes significantly compared to prior stages
    2. Dysrhythmia Risk (longterm risk into adulthood)
      1. Atrial Dysrhythmias are most common (Atrial Fibrillation, Atrial Flutter, PSVT)
      2. Supraventricular Tachycardia Management is the same as for other patients (e.g. Adenosine, cardioversion)
    3. Thrombosis Risk
      1. Aspirin or other antiplatelet agent OR
      2. Anticoagulation

VIII. Prognosis

  1. Single ventricle conditions are uniformly fatal without circulation
  2. Staged procedures for Single Ventricle Defects have resulted in survival to adulthood in 70% of cases

IX. References

  1. Claudius and Stroebel in Swadron (2021) EM:Rap 21(11): 6-9
  2. Civitarese and Crane (2016) Crit Dec Emerg Med 30(1): 14-23
  3. Sloas and Orman in Majoewsky (2013) EM:Rap 13(9): 10-11
  4. Rao in Berger (2013) Pediatric Hypoplastic Left Heart Syndrome, Emedicine
    1. http://emedicine.medscape.com/article/890196-overview#showall

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