Management of the hypercyanotic spell
Overcoming a hypercyanotic spell requires maneuvers to
re-establish adequate balance between the systemic and
pulmonary flows. Treatment must focus on decreasing
pulmonary, and increasing systemic, vascular resistance,
hence promoting left to right flow across the ventricular
septal defect and into the subpulmonary outlet.
Parents at home with a child suffering such spells are
taught to place their child in the knee-to-chest position in
an effort to increase systemic vascular resistance and promote
systemic venous return to the right heart. This will
theoretically increase intracardiac shunting from left-toright
across the interventricular communication, as well as
increase the preload of the right ventricle. Emergency services
should be contacted immediately.
Medical management will consist of establishing immediate
intravenous access to allow prompt administration of
fluids, which will improve right ventricular preload. Oxygen
should be initiated to decrease peripheral pulmonary
vasoconstriction, and improve oxygenation once flow of
blood to the lungs is re-established. Subcutaneous morphine
should be administered to decrease the release of
catecholamines. This will increase the period of right ventricular
filling by decreasing the heart rate, and promote
relaxation of the infundibular spasm. If the patient
remains hypercyanotic after these measures, he or she
should be paralysed and intubated, with phenylephrine
administered intravenously to increase systemic vascular
resistance.
The long half-life, and potential side effects, such as hypotension
and cardiac dysfunction, of beta blockers precludes
their routine use in the emergency situation.
Propranolol has been used in small doses in the chronic
care of patients deemed to be at risk for spells in an effort
to minimise the infundibular spasm responsible for the
episodes. Once a patient requires prophylaxis by betablockade,
surgical referral should occur to prevent the
potential tragic and unpredictable outcome of a hypercyanotic
spell [10].