**7.1 Non-invasive imaging**

In current times, transthoracic echocardiogram (TTE) is the main modality for definitive diagnosis of VSDs. It allows to delineate size and location of the defect as well as other details such as outflow tracts, associated lesions, evidence of chamber dilation and pressures (**Figures 3–6**). Transesophageal echocardiographic (TEE)

#### **Figure 3.**

*Echocardiographic parasternal long axis view showing perimembranous ventricular septal defect (VSD). RV = right ventricle; LV = left ventricle.*

#### **Figure 4.**

*Echocardiographic parasternal short axis color compare view showing perimembranous ventricular septal defect (VSD) at ~11o' clock position. The red flow represents indicates left to right shunt during systole across it.*

#### **Figure 5.**

*Echocardigraphic image (parasternal short axis color compare view) showing subarterial ventricular septal defect (VSD) at ~12–1 o'clock position. The red flow represents indicates left to right shunt during systole across it.*

imaging is routinely used for evaluation of anatomy intraoperatively. It also helps to better delineate associated pathologies especially those involving valve abnormalities such as valve prolapse and regurgitation. Postoperatively, it is used to detect presence of residual defects as well as ventricular function assessment.

#### **Figure 6.**

*Echocardiographic parasternal long axis view showing trivial aortic regurgitation (AR) is seen by color flow in the presence of aortic cusp prolapse into the subarterial ventricular septal defect (VSD).*

Electrocardiographic changes such as left atrial enlargement as well as left ventricular hypertrophy is seen in hemodynamically significant defects. Right ventricular hypertrophy maybe seen in patients with significant pulmonary arterial hypertension. Chest X-rays serve as adjuncts to clinical assessment. Cardiomegaly, and increased pulmonary vascular markings are seen in patients with moderate to large VSDs. Left atrial dilation may cause superior deviation of the left main bronchus. In patients with Eisenmenger's, there is evidence of right heart enlargement with main pulmonary artery dilation without increased pulmonary vascular markings.

Advanced imaging such as cardiac magnetic resonance (CMR) imaging is not necessary in the routine evaluation of isolated VSDs. However, it is a helpful adjunct in the diagnosis of complex anatomical variants and in the evaluation of associated defects or complications such as double chambered right ventricle and pulmonary arterial hypertension (PAH). 3D phase contrast-CMR may help obtain additional information with regards to quantification of pulmonary blood flow.
