Tetralogy of Fallot

(Redirected from Tet Spell)


  • Most common cyanotic CHD manifesting in post-infancy period
  • Acute episodes of hypoxia and cyanosis caused by right-to-left shunting across the VSD ('Tet Spells')
  • Patients may present with irritability, agitation, grunting, crying, and central cyanosis
  • May have history of squatting during spells (increases systemic vascular resistance)
  • During cyanotic spells, there is either:
  1. Increased pulmonary outflow obstruction 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


  • VSD
  • RV outflow obstruction (pulmonic stenosis)
  • Overriding aorta
  • RV hypertrophy

Clinical Features

Digital clubbing with cyanotic nail beds in an otherwise healthy-appearing, asymptomatic young adult with Tetralogy of Fallot.
  • 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

Syncope (peds)

Congenital Heart Disease Types


CXR of child with tetralogy of Fallot
  • Echocardiography: Gold standard
  • CXR: shows the classic “boot-shaped” heart
    • Decreased pulmonary vascularity (due to pulmonic stenosis)


  • Acute Presentation (Tet spell):

Knee-to-Chest Position

Knee to chest positioning of patient
  • 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

Conservative Measures

  • Avoid needle sticks if possible as crying worsens pulmonary vascular resistance and right-to-left shunt
    • Consider intranasal or intramuscular medications if needed
  • Permit child to remain with parents
  • Maintain calm, quiet, dim room to reduce agitation
  • Consider IO line as resuscitation tool


  • 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
  • Intranasal Fentanyl 1.5-2 mcg/kg range [4]
    • Only one case report but IN administration may avoid the pain from a needle stick


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


  • 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 consultation 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


  • pRBCs 5-10 cc/kg IV over 5hrs

Prostaglandin E1

  • Appropriate in neonatal period only (prior to closure of ductus arteriosus)
  • 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
    • Often staged repair, completed over several surgeries
  • Optimal age for correction controversial, but if elective repair, 3-11 months of age may be best[6]


  • Admit

See Also


  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 tetralogy 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.