Complex sentence: This disorder is a form of long QT syndrome, which is a heart condition that causes the cardiac muscle to take longer than usual to recharge between beats; if untreated, the irregular heartbeats can lead to fainting, seizures, or sudden death.
Split into simpler sentences: This disorder is a form of long QT syndrome, which is a heart condition that causes the cardiac muscle to take longer than usual to recharge between beats. If untreated, the irregular heartbeats can lead to fainting, seizures, or sudden death.