Harvey's Garden

Cyanotic congenital heart defects

4 min read

Tricuspid Valve Atresia (TVA)

  • Epidemiology & Pathophysiology
    • Congenital agenesis of the tricuspid valve No communication between RA and RV.
    • Hypoplastic RV (underdeveloped).
    • Survival depends on obligatory R L shunt (ASD/PFO) for mixing and VSD or PDA for pulmonary blood flow.
    • 3rd most common form of cyanotic CHD.
  • Clinical Features
    • Cyanosis: Present at birth or shortly after (severity depends on magnitude of pulmonary blood flow).
    • Heart Sounds:
      • Single S2 (pulmonary valve usually involved/hypoplastic).
      • Holosystolic murmur at LLSB (due to VSD) is common.
    • Symptoms: Tachypnea, poor feeding, hypoxic spells (if pulmonary flow is restricted).
  • Diagnosis
    • ECG (High-Yield):
      • Left Axis Deviation (LAD).
      • Left Ventricular Hypertrophy (LVH) (Since RV is hypoplastic, LV does all the pumping).
      • Note: Most other cyanotic CHDs (e.g., TOF) show RAD and RVH.
      • Tall, peaked P waves (RA enlargement). c
    • CXR:
      • Decreased pulmonary vascular markings (oligemia). c
      • Heart size normal or slightly enlarged; R heart border rounding (RAE).
    • Echocardiogram (Confirmatory/Gold Standard):
      • Demonstrates absence of tricuspid valve.
      • Hypoplastic RV.
      • Presence of ASD/VSD/PDA.
  • Differential Diagnostics
    • Tetralogy of Fallot (TOF): Diff by ECG (RAD, RVH) and CXR (“Boot-shaped heart”).
    • Ebstein Anomaly: Displacement of TV leaflets (not atresia). Diff by CXR (“Wall-to-wall” heart/Box-shaped), ECG (WPW association, RBBB).
    • Transposition of Great Arteries (TGA): Diff by “Egg-on-string” CXR, severe cyanosis within hours, ECG (RAD).
    • Total Anomalous Pulmonary Venous Return (TAPVR): Diff by “Snowman” sign on CXR, ECG (RAD).
    • Pulmonary Atresia with Intact Ventricular Septum: Clinical picture very similar to TVA (hypoplastic RV + LAD on ECG); distinguished by Echo.
  • Management
    • Immediate Stabilization:
      • IV Prostaglandin E1 (PGE1): Critical first step to maintain PDA and ensuring pulmonary blood flow.
    • Surgical Repair (Staged Palliative Pathway):
      1. Neonatal: Systemic-to-pulmonary shunt (e.g., Blalock-Taussig shunt) or PA banding (if excessive flow).
      2. 4-6 Months: Bidirectional Glenn procedure (SVC connected to Pulmonary Artery).
      3. 2-4 Years: Fontan procedure (IVC connected to Pulmonary Artery).
    • End Goal: Passive venous return to lungs; Single ventricle (LV) pumps oxygenated blood to body.
  • Complications
    • Paradoxical Emboli (Stroke risk due to R L shunting).
    • Arrhythmias (Atrial flutter/fib due to RA dilation/scarring).
    • Post-Fontan:
      • Protein-Losing Enteropathy (PLE).
      • Plastic Bronchitis.
      • Thrombosis.

Total Anomalous Pulmonary Venous Return (TAPVR)

  • Epidemiology & Pathophysiology

    • Mech: All 4 pulm veins drain into systemic venous circ (SVC, RA, Coronary Sinus) instead of LA.
    • Requirement: Must have ASD or PFO for R→L shunt to sustain life (mixed blood → systemic).
    • Class: Cyanotic Congenital Heart Disease (R→L shunt physiology).

  • Clinical Features

    • Presentation varies by obstruction
    • Obstructed (Infrastructure usually): Severe cyanosis/respiratory distress at birth (Pulm Edema). Sick neonate.
    • Non-obstructed: Mild cyanosis, HF sxs (tachypnea, poor feeding) in infancy (weeks-months).
    • Physical Exam:
      • Heart Sounds: Fixed split S2 (due to RV volume overload/ASD).
      • Murmur: Systolic ejection murmur at LUSB (increased flow across pulm valve). Diastolic rumble(increased flow across tricuspid).
      • Signs of HF: Hepatomegaly, RV heave.

  • Diagnosis

    • Initial/Screening:
      • CXR:
        • “Snowman” sign (or Figure-of-8): Dilated SVC + Vertical Vein + Cardiac shadow. Note: Often not seen in neonates due to thymus.
        • Increased pulm vascular markings (pulm congestion).
      • ECG: RAD, RVH (RV volume overload).
    • Confirmatory/Gold Standard:
      • Echocardiogram: Visualizes confluent vein behind LA; veins not entering LA. Dilated RA/RV.
    • Other:
      • Cardiac Cath: Only if Echo inconclusive (rarely needed). Shows O2 sat step-up in RA/SVC.

  • Differential Diagnostics

    • RDS (Respiratory Distress Syndrome): Preterm, ground-glass on CXR. No fixed split S2.
    • Transposition of Great Arteries (TGA): “Egg on a string” CXR. Cyanosis immediate.Single S2.
    • Tetralogy of Fallot: “Boot-shaped heart”. VSD murmur. Cyanosis depends on RVOT obstruction degree (“Tet spells”).
    • Persistent Pulm HTN of Newborn (PPHN): Structurally normal heart, severe hypoxemia.

  • Management

    1. Stabilization (ABC):
      • O2, intubation if resp failure.
      • Inotropes for HF.
      • PGE1 (Prostaglandin): Usually not helpful (unlike ductal-dependent lesions like Coarctation or TGA) unless obstruction is severe and systemic flow is compromised, but rarely main mgmt.
      • ECMO: If severe hypoxia/instability pre-op.
    2. Surgical Repair (Definitive):
      • Obstructed: Emergent surgery.
      • Non-obstructed: Elective but prompt repair (prevent pulm HTN).
    3. Procedure: Anastomosis of common pulm vein to LA; closure of ASD.

  • Complications

    • Pulmonary Vein Stenosis (post-op).
    • Arrhythmias (atrial).
    • Pulmonary HTN (if repair delayed).

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