الفهرس 
EMBRYOLOGYOnly 14 pages are availabe for public view
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Abstract
Atrioventricular (AV) septal defects are characterized by a deficiency or absence of septal tissue immediately above and below the normal level of the AV valves, including the region normally occupied by the AV septum, in hearts with two ventricles.
The atrioventricular septal defect is a congenital malformation of the heart. The prevalence is 3-4% of all congenital cardiac malformation.
Patients with complete AV septal defect, presentation is usually in the first year of life, frequently during the first months, as a result of progressive severe heart failure, which may not be controllable medically. Congestive heart failure and pulmonary artery hypertension are associated with feeding difficulties, abnormal energy expenditure, and failure to thrive.
Patients with complete AV septal defects, medical therapy consists of anticongestive treatment for the signs and symptoms of congestive heart failure. The mainstays of medical therapy are Diuretics, digoxin, and ACE- inhibitors.
In several studies, pulmonary artery banding, as a palliative procedure in early infancy, is no longer recommended unless other associated abnormalities make primary repair a high-risk operation.
Surgical repair is considered to be the definitive treatment for atrioventricular septal defect (AVSD). The first successful repair of a complete AV septal defect was performed by Lillehei and colleagues in 1954, using cross-circulation and direct suture of the atrial rim of the septal defect to the crest of the ventricular septum. In 1955 began repairing AV septal defects by open cardiotomy and use of the pump-oxygenator.
Early experiences with complete AV septal defects were all associated with a high hospital mortality, often related to complete heart block, postrepair left AV valve regurgitation, or creation of subaortic stenosis. In 1958, Lev‟s description of the location of the bundle of His provided the basis for repair techniques that avoid heart block. Surgical treatment of AV septal defects is directed toward:
(1) Closing the interatrial communication, which is virtually always present
(2) Closing the interventricular communication if one is present
(3) Avoiding damage to the AV node and bundle of His
(4) Maintaining or creating two competent, nonstenotic AV valves.
Better understanding of the pathoanatomic features of this disease, careful timing of the surgery, advances in surgical technique, and improvements in the preoperative and postoperative management have reduced the postoperative morbidity and mortality.
There are many techniques in reparing complete atrioventricular septal defect including: double patch technique, classic single patch technique, modified sinfle patch technique, and recently no patch technique.
There are many centers that currently use the two patch technique using a Gore-Tex or Dacron patch for the ventricular component and a pericardial patch for the atrial component.
There are also groups that still use the “classic” single-patch technique, which involves using a portion of the pericardial patch for the ventricular component, cutting the AV valve, and resuspending the AV valve to the middle of this pericardial patch. The top portion of the pericardial patch is then used to close the atrial septal defect.
When closing the VSD with the modified single-patch technique, a series of not-pledgeted, interrupted, horizontal mattress sutures (Polypropylene) was first placed on the right side of the ventricular septal crest. These sutures were passed through the midportion of the common atrioventricular (AV) valve leaflet and through a harvested autologous pericardial patch, after which they were tied off and obliterated the interventricular component. The degree of cleft closure depended on the anatomy of the AV valve. The primum atrial septal defect (ASD) was closed with a pericardial patch with a continuous suture.
The choice of a double patch for cleft closure rather than a single patch is debatable. Both techniques provide good early and late results and no significant differences have been observed in the incidence of mortality, reoperation, or postoperative complete heart block between these two techniques.Some authors prefer to use the double-patch technique for AVSD closure because it produces less AV valve distortion and avoids dividing the bridging leaflet in a type C defect, which is always necessary in the single-patch technique.
The modified single-patch repair required shorter cardiopulmonary bypass and aortic cross-clamp times. In addition, there were no differences in LAVV regurgitation grade, indexed LAVV coaptation length, LAVV coaptation point, or indexed LVOT diameters.
The obliteration of a large VSD without a patch may produce important tension between the common AV valve and the crest of the ventricular septum.
The focus on repairing complete atrioventricular septal defects earlier and earlier in infancy is certainly facilitated by the modified single-patch technique. The removal of the VSD patch from the operation considerably reduces the degree of difficulty of this procedure. It also removes a potential source of error.