**9. Investigations**

### **9.1 Electrocardiogram**

As previously described, AV node is displaced posteriorly and inferiorly in these defects; this may result in prolongation of the PR interval. There will be a left superior deviation of the mean frontal plane vector. Biventricular hypertrophy is seen in complete and intermediate forms. Right ventricular hypertrophy is seen in the partial

#### **Figure 10.**

*12-lead EKG in patient with CAVSD showing left superior axis deviation and right ventricular hypertrophy.*

form. If there is moderate to severe mitral insufficiency, left ventricular hypertrophy may be seen. Other abnormalities which might be seen are prolongation of PR interval (**Figure 10**) [20].

### **9.2 Chest roentgenogram**

Chest roentgenogram shows cardiomegaly with increased pulmonary vascular markings. Features of pulmonary edema may be seen in subjects with congestive heart failure.

## **9.3 Echocardiography**

Echocardiography is the primary diagnostic modality for the evaluation of atrioventricular septal AV defects [21]. Assessment of the ASD can be best done from a subcostal coronal and sagittal view. VSD could be best evaluated in the parasternal short axis. En-face view of the common AV valves is best achieved with a modified subcostal left anterior oblique view (**Figure 11**). This view also demonstrates the bridging leaflets, their attachments and helps with the Rastelli classification in patients with complete AVSDs. Subcostal short axis view would assess atrial or ventricular level unbalance. An Apical four-chamber view would augment the information on previously mentioned variables along with AV valve inflow and regurgitation. Overall, all the views complement each other to get comprehensive information, as in any other heart. Associated malformations like tetralogy of Fallot, coarctation, patent ductus arteriosus, arch sidedness should be evaluated using modified subcostal right anterior oblique/parasternal long axis and high parasternal/suprasternal views [22]. 3D echocardiography demonstrates a comprehensive and accurate assessment of the size and extent of the septal defects, size, number, and abnormalities of AV valve leaflets and their attachment sites, as well as the relation of the valvular structures to the great vessels [23]. Other findings such as double orifice left AV-valve, single papillary muscle should be evaluated.

*DOI: http://dx.doi.org/10.5772/intechopen.105615 Atrioventricular Septal Defects*

#### **Figure 11.**

*Echocardiogam left anterior oblique (LAO) view. 1. Rastelli type a with attachments of the anterior/superior bridging leaflet (SBL) to crest of venticular septum; B. when valve is closed, notice the cleft in LAVV valve; C. Rastelli type C with "free floating" anterior bridging leaflet (<−>) and chordal attachments to right ventricular (RV) free wall (−>); D. 3D image showing tri-foliate cleft LAVV. IBL, inferior bridging leaflet; ML, mural leaflet; RAL, right anterior leaflet; RPL, right posterior leaflet; ML, left mural leaflet; LV, left ventricle.*

In determining the balance of ventricles, a quantitative approach was proposed by Cohen et al. [24] using a subcostal sagittal view. In this view, they measured the area of AV valve over each ventricle and calculated a left/right ventricular ratio, also known as AV valve index (AVVI). Based on the index, patients were stratified either to single-ventricle or bi-ventricular repair pathways. Patients with an AVVI <0.67 and a large VSD would be considered for the single-ventricle pathway. This was modified to the left AV valve area/total area. An AVVI >0.6 is considered left ventricular dominant whereas AVVI <0.4 was considered right ventricular dominant. It is important after surgical repair to assess for residual defects, progressive LVOT obstruction, AVV stenosis and regurgitation, systolic function.

## **9.4 Cardiac catheterization**

Cardiac catheterization is not frequently performed in AVSDs. However, it is helpful in assessing the hemodynamic information like the degree of shunting, pulmonary vascular resistance. One would see the characteristic "gooseneck appearance" from elongated LVOT on angiography. Patients with severely elevated PVR are poor candidates for full repair and may eventually be candidates for lung transplantation [25].

#### **9.5 Advanced cardiac imaging**

Cardiac computed tomography (CT) is particularly helpful to assess for any extracardiac defects or associated anomalies in these patients. Retrospective gated approach is useful for the evaluation of ventricular function and ventricular sizes, allows volumetric measurements, and also allows evaluation of ventricular function and wall motion. This may be of particular relevance in patients with hypoplastic ventricles and unbalanced AVSDs [26]. Cardiac magnetic resonance imaging (MRI) is an important tool to assess the degree of unbalance and guide for future surgical planning. These modalities have proven to decrease the amount of radiation exposure during cardiac catheterization [27].
