الفهرس 
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Abstract
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UMMARY
etralogy of Fallot is a congenital cardiac malformation that consists of an interventricular communication, also known as a ventricular septal defect, obstruction of the right ventricular outflow tract, overriding of the ventricular septum by the aortic root, and right ventricular hypertrophy. This combination of lesions occurs in 3 of every 10,000 live births, and accounts for 7-10% of all congenital cardiac malformations.
The development of tetralogy of Fallot is multifactorial; it has been associated with untreated maternal diabetes, maternal intake of retinoic acid, phenylketonuria, chromosomal anomalies (trisomies 21, 18, 13), microdeletions of chromosome 22q11.2, and Alagille syndrome with JAG1/NOTCH2 mutations.
Arrhythmia prevention is not feasible for all pediatric cardiac surgery patients. Thus, high-risk patients must be identified. Many predicted criteria have been offered; however, they lack accuracy. The aim of this work is to characterize patients with risk of arrhythmia (SVT or Junctional), identify its predictors and prognosis in selected TOF patients undergoing total repair at Ain Shams university, Cardiothoracic department.
It is a prospective observational study on 65 pediatric patients who underwent total correction of TOF. On admission, all patients were investigated thoroughly by assessing their fitness to surgery through conducting preoperative laboratory tests and ECG. A recent chest X-ray and ECHO were mandatory. Furthermore, the cases were carefully examined by our pediatrics
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team. This study conducted at Ain Shams University hospitals, Cardiothoracic department on TOF patients undergoing total repair.
In the present study, the prevalence of post operative arrhythmia was found to be 27%, which is consistent with the results of many recent studies. We observed that JET was the most common arrhythmia detected post-operatively. In the current study, 17 patients (26%) developed JET and 1 patient (1.5%) suffered from heart block. Nearly 40% of the patients showed one kind of permanent electrocardiographic abnormality in the form of RBB early after TOF total correction.
Various risk factors for arrhythmia described in the literature include younger age at surgery, low body weight, prolonged CPB time, longer aortic cross clamp time, cyanosis, deep hypothermic circulatory arrest, and use of Milrinone. Results of the current study indicated no direct relationships between the occurrence of JET and gender, weight, level of preoperative oxygen saturation, percentage of cyanotic spells, ECHO hemodynamic parameters (VSD size, RVOT gradient, associated valve disorders, pulmonary arteries sizes and McGoon index), CPB, CCT, cardioplegia type, approach, use of TAP, VSD closure technique, use of RVOT patch, previous shunt, intra-op temperature, and the type of inotropic support used. However, there were a significant relationship between younger age of operation and lower pulmonary annulus size with the occurrence of JET.
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The younger age can be explained by the fact that complex surgical interventions if more frequent at an early age, cause the biggest impact in favor of arrhythmia as the sensitivity to electrolyte and acid base disorder is higher early in life. Furthermore, younger patients are generally sicker and smaller hearts are more prone to damage by surgical technique and retraction. The disruption to the proximal right bundle branch as in courses around the rim of VSD, either by VSD repair, or by delay or block in the peripheral right ventricular Purkinje fibers, is the etiology of RBBB following TOF repair