Atrial septal defects (ASDs) can go undiagnosed in childhood and in some cases may first come to medical attention during adolescence or adulthood. In such instances, patients commonly present with palpitations and exercise intolerance. The initial echocardiographic examination focuses on diagnosis and hemodynamic assessment of the defect. Precise definition of atrial septal anatomy, identification of coexisting anomalies, quantification of shunt size and right ventricular systolic pressure, are important aspects of the assessment (also refer to Chap.​ 7). In the adult population, TEE is more sensitive than TTE in detecting atrial communications, especially sinus venosus defects located near the junction of the superior vena cava and right atrium (Fig. 18.1). In general, all ASDs should be imaged in multiple planes in order to determine location and defect size. Determination of adequate rims is important in the case of a secundum ASD for consideration regarding transcatheter device closure (Videos 18.1 and 18.2). Three-dimensional imaging may offer additional benefits in this regard [14]. In general, secundum defects under 40 mm in balloon stretched diameter (Fig. 18.2, Video 18.3) and those with adequate rims are considered potentially suitable for percutaneous device closure [15]. TEE also plays an important role in guiding transcatheter device placement, evaluating residual shunting, and determining device stability (Fig. 18.3, Video 18.4). TEE following transcatheter device closure can identify complications related to the occluder such as thrombus formation [16].

Ventricular septal defects (VSDs) may be classified as muscular or non-muscular, aligned or malaligned, and restrictive or non-restrictive. The most common site for an unrepaired VSD in the adult is in the membranous septum, followed by muscular, inlet, and outlet septum.

The ventricular septum cannot be fully imaged in any one or a single plane because it is a curved structure (refer to Chap.​ 9). Communications in the region of the membranous septum are best seen in the mid esophageal four chamber (ME 4 Ch) view with probe anteflexion. Additional views to define this type of defect include the mid esophageal right ventricular inflow-outflow (ME RV In-Out) and mid esophageal long axis (ME LAX) views (Fig. 18.4, Video 18.5). Continuous wave Doppler allows estimation of shunt velocity and classification into a restrictive versus non-restrictive defect, if the peak velocity across the defect is high or low respectively. Spontaneous closure of a membranous VSD usually occurs by adherence of a redundant aneurysmal tricuspid septal leaflet to the membranous septum. This may be seen in several planes but is best imaged in the 30–60° mid esophageal aortic valve short axis (ME AV SAX) view.

Imaging and Doppler interrogation of the right ventricle may identify anomalous muscle bundles resulting in a high-pressure proximal chamber and a low-pressure distal chamber characteristic of double-chambered right ventricle (DCRV) (Fig. 18.5, Video 18.6). It has been proposed that this is an acquired lesion potentially related to chronic high velocity VSD flow impacting the right ventricle, however, some controversy still remains regarding this notion. This anomaly is best assessed in the mid esophageal position in the ME RV In-Out view (between 30° and 60°) or from the deep transgastric sagittal (DTG Sagittal) view [17]. Isolated DCRV without a VSD is exceedingly rare.

Occasionally, a patient with a repaired or unrepaired membranous VSD may have a left ventricular-to-right atrial shunt known as a “Gerbode defect”. This is usually a high velocity shunt that may be confused with a jet of high pressure tricuspid regurgitation. This is best seen in the ME 4 Ch and ME RV In-Out views.

A malaligned VSD is associated with great artery annular overriding; typically the aorta overrides the septum as seen in patients with tetralogy of Fallot. The ventriculoarterial connections and malaligned VSD are often best seen in the mid esophageal aortic valve long axis (ME AV LAX) or ME LAX views. Prolapse of the aortic valve (usually the right coronary cusp) into the VSD may cause partial closure of the defect and/or aortic regurgitation. This is seen in outlet (conal or supracristal) defects and is best appreciated in the ME LAX or ME RV In-Out views.

Following surgical or transcatheter VSD closure, interrogation of the septal patch or device for leaks and position as well as assessment of nearby structures is important, preferably done in the operating room or catheterization laboratory at the time of defect closure [18, 19]. In addition, color flow Doppler interrogation of the entire septum in multiple planes may reveal previously undetected small muscular VSDs. TEE plays an important role in transcatheter device occlusion by providing monitoring and guidance during the procedure, decreasing radiation exposure and allowing for detections of complications (refer to Chap.​ 17).

Atrioventricular canal defects, also known as atrioventricular septal defects (AVSDs) or endocardial cushion defects, are a group of malformations that share a common embryologic defect related to the endocardial cushions (refer to Chap.​ 8). This region influences the development of the atrioventricular septum and the atrioventricular valves.

In the “partial” form, a primum ASD is present with either a restrictive ventricular septal defect (VSD) or intact ventricular septum. This is frequently associated with a commissure or cleft in the anterior mitral leaflet (Fig. 18.6, Video 18.7). The “complete” form of the AVSD is characterized by the presence of a common atrioventricular valve, primum ASD and inlet VSD. The deficiency of the inlet ventricular septum along with abnormalities of the atrioventricular valves (overriding, straddling, and/or cleft) produces an elongated left ventricular outflow tract that has characteristically been described as having a “goose neck” appearance on left ventriculography. Subaortic stenosis is a common association often caused by chordal attachments of the left atrioventricular valve (mitral valve) to the left ventricular outflow septum (Fig. 18.6, Video 18.8).

Patients with complete defects frequently undergo definitive surgical repair in infancy. Palliated or unrepaired defects are now rarely seen in adulthood. Palliation is usually in the form of a pulmonary artery band aimed at restricting pulmonary blood flow. Unrepaired defects in adulthood are likely associated with severely elevated pulmonary vascular resistance (Eisenmenger syndrome) and cyanosis related to reversal in the direction of the shunt.

Presentation of an AVSD in the adult patient is most frequently in the form of a partial defect and associated mitral regurgitation. Chordal attachments to the ventricular septum may account for subaortic stenosis and symptomatology. In patients who have undergone a prior repair, TEE is predominantly utilized to evaluate the reconstructed atrioventricular valve(s), with special attention to the degree, etiology, and progression of regurgitation, iatrogenic stenosis, and presence/degree of subaortic stenosis.

TEE evaluation of the mitral apparatus is best done in the mid esophageal and transgastric locations. The various planes that display the mitral valve apparatus are essential for comprehensive visualization of the base and tips of the leaflets with dedicated imaging of the valve scallops from 0° to 180° (refer to Chaps.​ 4 and 8). The transgastric basal short axis view (TG Basal SAX) that displays the mitral valve in short axis is helpful for direct visualization of the commissure or cleft in the anterior leaflet and all of the scallops of the posterior leaflet (Fig. 18.6, Video 18.7). Color flow Doppler interrogation in this view demonstrates the location and etiology of mitral regurgitation. Short axis views at the level of the mid left ventricular cavity—known as the transgastric mid short axis (TG Mid SAX) views—define papillary muscle anatomy and chordal attachments. In the deep transgastric long axis (DTG LAX) view, flow acceleration in the region of the chordae should arouse the suspicion of subaortic stenosis. The tricuspid valve is also well seen in the ME RV In-Out view and from the transgastric location in the transgastric right ventricular inflow (TG RV In) view.

Interrogation of residual intracardiac shunts, particularly in the case of defects that involve a ventricular level communication or ventriculoatrial shunt, requires the use of multiple planes and is assisted by color flow Doppler imaging.

Pulmonary venous connections are well imaged by TEE (also refer to Chap.​ 6). In the normal heart, the right and left upper pulmonary veins are usually identified draining into the left atrium at the level of the mid esophagus in the horizontal or transverse plane from zero to 30° with movement of the probe towards the right and left respectively. The left upper pulmonary vein courses into the left atrium posterolateral to the left atrial appendage. The vertical or longitudinal plane at approximately 90° allows visualization of the left and right lower pulmonary veins as they enter the left atrium but modifications of the interrogating plane maybe necessary.

Determination of pulmonary venous anatomy is imperative in patients with ASDs because anomalous pulmonary venous drainage may necessitate surgical intervention as opposed to simple percutaneous closure of an interatrial communication. The most common malformation in this setting is the presence of an anomalous right upper pulmonary vein entering at the junction of the superior vena cava and right atrium in the presence of a superior sinus venosus ASD. Anomalous pulmonary venous connections to the low superior vena cava (between the azygous vein and right atrium) can be visualized by TEE imaging. The probe is positioned at the level of the superior vena cava-right atrial junction with imaging of this area performed in the ME 4 Ch and in the mid esophageal bicaval (ME Bicaval) views. A comprehensive assessment of this defect can be challenging solely on the basis of TEE. In many cases preoperative imaging with modalities such as chest-computed tomography, magnetic resonance imaging, or cardiac catheterization and angiography may be undertaken.

Uncorrected total anomalous pulmonary venous return is an unusual presentation in the adult but may be seen in patients who have received limited or no medical attention, for example, those in third world countries where the resources for appropriate diagnosis and therapies are lacking. A common form of total anomalous pulmonary venous connection seen in adults is the presence of a posteriorly located pulmonary venous confluence chamber into which all four pulmonary veins drain (Fig. 18.7). This chamber is not connected to the left atrium despite the close proximity of these two structures. The confluence typically drains into a greatly dilated coronary sinus that thereafter drains into a dilated right atrium. The presence of a patent foramen ovale or atrial septal defect is necessary to allow venous admixture. In some cases this condition may be confused with cor triatriatum because the close proximity of the venous confluence to the left atrium gives the appearance of a dividing membrane in the left atrium. Less frequently, a vertical vein or other venous structure connects the pulmonary venous confluence to the innominate vein, superior vena cava or travels below the level of the diaphragm to anastomose with the portal vein or a hepatic vein.