Tetralogy of Fallot is the most common congenital heart defect. It involves abnormalities of the heart walls, septum and blood vessels including the aorta.
Sick sinus syndrome is arrhythmia or abnormal heartbeat caused by dysfunction of the sinus node, the heart's natural pacemaker, often after a heart attack.
Croup is usually cause by infection with viral laryngotracheobronchitis. It causes a hoarse voice, barking cough and a high-pitched wheeze on inhalation.