Tetralogy of fallot

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Background

  • Most common cyanotic CHD manifesting in post-infancy period. Tet spells are acute episodes of hypoxia and cyanosis caused by right-to-left shunting across the VSD. Patients will present with irritability, agitation, grunting, crying, and central cyanosis.
  • During cyanotic spells, there is either:
  1. Increased pulmonary outflow obstruction and/or
  2. Decreased systemic vascular resistance leading to right-to-left shunting
  • During the spell there is hypercarbia and hypoxemia (which further increases pulmonary vascular resistance). The process compounds itself creating worsening right-to-left shunting, hyperpnea, right outflow tract obstruction and increased systemic venous return.

Tetralogy

  1. VSD
  2. RV outflow obstruction (pulmonic stenosis)
  3. Overriding aorta
  4. RV hypertrophy

Clinical Features

  • Systolic ejection murmur along the left sternal border[1]
  • Cyanosis worse during feeding and crying[1]
  • May squat to relieve symptoms: increases afterload and decreases shunt[1]
  • Acute respiratory distress (Tet Spells) due to increased right outflow tract obstruction[1]
  • Chronic hypoxemia causes a compensatory polycythemia and clubbing of the fingers and toes

Differential Diagnosis

Congenital Heart Disease Types

Evaluation

  • Echo
  • CXR: shows the classic “boot-shaped” heart
    • Decreased pulmonary vascularity (due to pulmonic stenosis)

Management[3]

  • Acute Presentation (Tet spell):

Knee-to-Chest Position

  • Two-fold mechanism to reduce right to left shunt
    • Reduces systemic venous return
    • Increases systemic vascular resistance
  • Done in the parent's arms or while lifting the patient onto the parents shoulders and tucking the knees underneath the chest
Knee-to-chest.JPG

Conservative Measures

  • If it can be helped, do not provoke infant with IV line (worsens crying, increasing pulmonary vascular resistance and right-to-left shunt)
  • Permit child to remain with parents
  • Consider IO line as resuscitation tool

Analgesia

  1. Morphine 0.1-0.2mg/kg IV or IM
    • Goal is to ideally avoid IV placement if possible
    • Decreases ventilatory drive, thus decreasing systemic venous return
    • Caveat is decrease in vascular resistance
  2. Intranasal Fentanyl 1.5-2 mcg/kg range [4]
    • Only one case report but IN administration may avoid the pain from a needle stick

Ketamine

  • 0.25 - 1.0mg/kg IV or 3-5 mg/kg IM
  • Benefit of sedation without decrease in vascular resistance

Phenylephrine

  • Dose: 0.2mg/kg IV
  • Increases SVR similar to knee to chest positioning

Sodium bicarbonate

IV fluids

  • 10-20 cc/kg bolus NS initially
  • Improves RV filling in the context of restrictive RV physiology

Beta blockers

  • Should be administered in consulation with cardiology and pediatric surgery
  • Relax spasm causing RV outflow obstruction
  • Slows HR, decrease right to left shunting
  • Propranolol IV 0.1-0.2mg/kg over 5min (preferred)
  • Alternatives when IV propranolol not available (switch to PO propranolol after)
    • Metoprolol IV 0.1mg/kg over 5 min, q5 min to max dose of 3x
      • Then may start infusion 1-5 mcg/kg/min
    • Esmolol 0.5mg/kg over 1 min, then 50 mcg/kg/min over 4 min

Transfusion

  • pRBCs 5-10 cc/kg IV over 5hrs

Prostaglandin E1

  • Start infusion at 0.05 mcg/kg/min IV and titrate up to 0.1 mcg/kg/min, monitoring for hypotension (and apnea)[5]
  • Maintains the ductus (which completely seals by ~3 wks)
  • Side Effects: Hypotension, Bradycardia, Seizures and Apnea

Definitive Treatment

  • Cardiothoracic surgery to repair the defects early before significant pulmonary hypertension develops
  • Optimal age for correction controversial, but if elective repair, 3-11 months of age may be best[6]

Disposition

See Also

References

  1. 1.0 1.1 1.2 1.3 Horeczko T, Inaba AS: Cardiac Disorders; in Marx JA, Hockberger RS, Walls RM, et al (eds): Rosen’s Emergency Medicine: Concepts and Clinical Practice, ed 8. St. Louis, Mosby, Inc., 2014, (Ch) 171: p 2139-2169.
  2. Knipe K et al. Cyanotic congenital heart diseases. Radiopaedia. http://radiopaedia.org/articles/cyanotic-congenital-heart-disease
  3. Sharma R. Kids Heart ICU. Cyanotic Spells. http://kidshearticu.com/cyanoticspells.asp
  4. Tsze DS, Vitberg YM, Berezow3 J, Starc TJ, Dayan PS. Treatment of tetrology of Fallot hypoxic spell with in- tranasal fentanyl. Pediatrics. 2014 Jul;134(1):e266-9.
  5. Donofrio MT, Moon-Grady AJ, Hornberger LK, Copel JA, Sklansky MS, Abuhamad A, Cuneo BF, Huhta JC, Jonas RA, Krishnan A, Lacey S, Lee W, Michelfelder EC Sr, Rempel GR, Silverman NH, Spray TL, Strasburger JF, Tworetzky W, Rychik J. Diagnosis and treatment of fetal cardiac disease: a scientific statement from the American Heart Association. American Heart Association Adults With Congenital Heart Disease Joint Committee of the Council on Cardiovascular Disease in the Young and Council on Clinical Cardiology, Council on Cardiovascular Surgery and Anesthesia, and Council on Cardiovascular and Stroke Nursing.Circulation. 2014 May 27;129(21):2183-242. doi: 10.1161/01.cir.0000437597.44550.5d. Epub 2014 Apr 24.
  6. Van Arsdell GS et al. What is the Optimal Age for Repair of Tetralogy of Fallot? Circulation. 2000; 102: Iii-123-Iii-129.

Authors

Claire