Cyanotic spells

Cyanotic spells

കുട്ടികളിൽ സയനോട്ടിക് സ്പെല്ലുകൾ (ടെറ്റ് സ്പെല്ലുകൾ)

बच्चों में सयनोटिक स्पेल्स (टेट स्पेल्स)

Cyanotic spells are episodes of worsening of cyanosis (also called hypercyanotic spells, Tet spell for short [1]) in infants with cyanotic congenital heart disease with low pulmonary blood flow (Tetralogy of Fallot physiology). Tet spells can also rarely occur in adults with Tetralogy of Fallot [1]. Cyanotic spells are associated with hyperpnea and may lead to loss of consciousness and even hypoxic seizures if the episodes are prolonged. They can be precipitated by crying or other forms of exertion.

A rare instance of refractory cyanotic spell in a patient with Tetralogy of Fallot due to thrombus in right ventricular outflow tract has also been described [2]. Thrombus occurred following intravenous iron sucrose therapy for iron deficiency, which is known to worsen hyperviscosity symptoms in Tetralogy of Fallot.

Mechanism of cyanotic spells

Proposed mechanism for the cyanotic spells are increase in contractility of the infundibulum enhancing obstruction and there by right to left shunt and immature respiratory center causing hyperventilation/hypoventilation, hypoxia vicious cycle. Another mechanism suggested is mechanoreceptor stimulation from the right ventricle. Increased contractility of right ventricle due to catecholamines and decreased right ventricular volume can trigger reflex hyperventilation and peripheral vasodilatation and initiate a spell [3].

Treatment of cyanotic spells

Conventional treatment of cyanotic spells or Tet spells is sedation with morphine, keeping in knee chest position, oxygen administration, hydration and intravenous propranolol. Knee chest position compresses the femoral arteries and veins, thereby enhancing the afterload and reducing return of desaturated blood from the lower limbs. Enhanced systemic afterload reduces right to left shunting across the ventricular septal defect and enhances the pulmonary blood flow.

Use of intranasal midazolam in an emergency situation in an infant with difficult venous access as the child was deeply cyanosed, crying and hyperpneic, has been reported [4]. Intravenous access could be easily obtained after termination of the spell. Another case in which the cyanotic spell in Tetralogy of Fallot could be relieved by intranasal fentanyl has also been reported [5].

An interesting case reported manual autotransfusion of blood from aorta to pulmonary artery for a refractory cyanotic spell occurring in the cardiac catheterization laboratory [6].

Blalock-Taussig (BT) shunt is useful in preventing cyanotic spells refractory to medical therapy, when immediate surgical correction of the cyanotic congenital heart disease is not feasible [7].

Cyanotic spells in D-TGA with LVOT obstruction

Cyanotic spells can occur due to dynamic left ventricular outflow tract obstruction (LVOTO) in infants with d-transposition of great arteries (D-TGA) and intact interventricular septum. Worsening of outflow tract gradient with isoproterenol and relief of obstruction with intravenous propranolol has been documented in these cases [8].

References

1. Weng YM, Chang YC, Chiu TF, Weng CS. Tet spell in an adult. Am J Emerg Med. 2009 Jan;27(1):130.e3-5.
   
2. Gupta SK, Saxena A, Anil OM, Bisoi AK. Thrombus in right ventricular outflow tract: unique cause of refractory cyanotic spell. Congenit Heart Dis. 2012 Jul-Aug;7(4):E56-8.
3. Kothari SS. Mechanism of cyanotic spells in tetralogy of Fallot–the missing link? Int J Cardiol. 1992 Oct;37(1):1-5.
4. Montero JV, Nieto EM, Vallejo IR, Montero SV. Intranasal midazolam for the emergency management of hypercyanotic spells in tetralogy of Fallot. Pediatr Emerg Care. 2015 Apr;31(4):269-71.
   
5. Tsze DS, Vitberg YM, Berezow J, Starc TJ, Dayan PS. Treatment of tetralogy of Fallot hypoxic spell with intranasal fentanyl. Pediatrics. 2014 Jul;134(1):e266-9.
   
6. Kothari SS, Ramakrishnan S, Bisoi AK. Emergency manual systemic-to-pulmonary artery autotransfusion for severe cyanotic spell. Catheter Cardiovasc Interv. 2011 Aug 1;78(2):280-1.
   
7. Kulkarni H, Rajani R, Dalvi B, Gupta KG, Vora A, Kelkar P. Effect of Blalock Taussig shunt on clinical parameters, left ventricular function and pulmonary arteries. J Postgrad Med. 1995 Apr-Jun;41(2):34-6.
8. Aziz KU, Paul MH, Idriss FS, Wilson AD, Muster AJ. Clinical manifestations of dynamic left ventricular outflow tract stenosis in infants with d-transposition of the great arteries with intact ventricular septum. Am J Cardiol. 1979 Aug;44(2):290-7.