To describe the types and incidence of cardiac dysrhythmias that occur under anesthesia in the present anesthesia environment.

It is unclear what the current state of anesthesia associated dysrhythmias is in the pediatric population. This was last investigated retrospectively in 1992 when the predominant volatile agent used for inhalation induction was halothane. Sevoflurane was approved by the Food and Drug Administration in 1995. Since that time, Sevoflurane has displaced halothane as the agent of choice for inhalation induction and has relegated halothane to be used in a narrow niche which primarily involves patients with very specific congenital heart diseases. It has been described that halothane has a larger proarrhythmic effect than sevoflurane for ventricular dysrhythmias. With the transition from the halothane to the sevoflurane era, a reassessment of the incidence and types of dysrhythmias occurring in non-cardiac pediatric patients is important.

Inclusion Criteria:

Children, while under anesthesia, having

1. circumstances of tachycardia and bradycardia,
2. administration of medications used in the treatment of dysrhythmias,
3. the commentary which includes comment about the heart rhythm or therapy for dysrhythmia,
4. in the quality assurance database for evidence of dysrhythmia

Exclusion Criteria:

Children with a known pre-operative:

1. prior history of dysrhythmia and/or
2. residual congenital heart disease
3. anti/pro dysrhythmic medications

All patients who have undergone anesthesia at the Children's Hospital of Philadelphia or at one of CHOP's satellite surgicenters, and whose anesthetic record was recorded electronically into the Compurecord system will be screened.