Atrial Septal Defect Dr. mahsa ghasemi

ASDs account for approximately 10% of all congenital heart disease and 20% to 40% of congenital heart disease occurring in adulthood.

Secundum Atrial Septal Defect. Secundum ASDs account for 75% of all ASDs and 30% to 40% of congenital disease seen in patients older than 40 years the Amplatzer may be used for defects up to 35 mm if adequate tissue rims are present ,whereas the Helex device may be used only for defects up to 17 to 18 mm Measurements should be taken in ventricular systole The rims are defined by adjacent structures —anterior (toward the aorta), posterior (toward the pulmonary veins), superior (toward the SVC), and inferior (toward the IVC)

Acceptable rim margins are 3 to 5 mm for the anterior rim and 5 to 7 mm for all other rims. A patent foramen ovale (PFO) is a related condition characterized by incomplete fusion of the septum primum and septum secundum following birth. It may be detected by saline contrast demonstration of a right-to-left interatrial shunt, typically with maneuvers that raise RA pressure (cough, Valsalva or Müller maneuver). It is a very frequent condition that occurs in 20% to 35% of the normal population. It is a common association with aneurysm of the interatrial septum

Primum Atrial Septal Defect. Primum ASDs account for 15% to 20% of ASDs and occur as part of the spectrum of atrioventricular canal defects. They may occur as isolated defects (partial atrioventricular canal defect) or be accompanied by inlet VSDs (complete atrioventricular canal defect). Partial canal defects typically have an associated cleft mitral valve. In complete canal defects there is a common single atrioventricular valve. Atrioventricular canal defects are the most common congenital heart abnormality in Down syndrome.

Sinus Venosus Atrial Septal Defect Sinus venosus ASDs account for 2% to 10% of ASDs and occur in two locations. The SVC type creates a confluence between the left atrium, right atrium, and SVC as it enters the right atrium. It is frequently accompanied by partial anomalous drainage of the right upper pulmonary vein, which is created when this vein enters the confluence. Partial anomalous drainage contributes to the left-to-right shunt.

IVC-type defects are less common and create a confluence between the left atrium, right atrium, and IVC as it enters the right atrium. They may be accompanied by partial anomalous drainage of the right lower pulmonary vein. These defects should be suspected in patients with markers of RV volume overload without apparent cause.

Coronary Sinus Atrial Septal Defect Coronary sinus ASDs are rare and may be associated with fenestrations or complete unroofing of the coronary sinus into the left atrium. They are frequently associated with a persistent left SVC, a more frequent finding (found in 0.3% of the general population) and the most common cause of a dilated coronary sinus in general. The diagnosis is facilitated with TEE.

The Echocardiography (Echo) Exam: Step-by-Step Approach

Step 1: Evaluate the Location of the Atrial Septal Defect • Most ASDs are best imaged from a subcostal view. • Parasternal short axis view may also be used. • The apical view is not used for measurements or assessment of most ASDs. • The atrial septum is thin, particularly in the region of the fossa ovalis. • From an apical view, the septum is parallel to the ultrasound beam, resulting in dropout. • Evaluate surrounding structures including PVs, the SVC, IVC, and CS. • Pulmonary venous anomalies are associated with sinus venosus defects. • Agitated saline solution is the preferred contrast used in pediatrics.

• Contrast echocardiography is performed by rapid injection of agitated saline solution into a peripheral vein. • Upper extremity veins are preferred. • Filling of the left atrium with contrast echoes confirms the presence of an interatrial communication. agitated saline injections may demonstrate the transient right-to-left shunts that occur in patients with dominant left-to-right shunting or evidence of negative contrast enhancement when the left-to-right shunt flow meets the contrast-enhanced RA blood

Step 2: Evaluate the Atrial Septal Defect Dimensions and Position

Step 3: Evaluate the Direction of the Shunt Step 4: Determine the Size of the Shunt

The two-dimensional appearance of RV volume overload and rightsided heart enlargement is considered evidence of a hemodynamically significant shunt (Qp/Qs ≥1.5:1). Qp/Qs may be calculated directly by applying the principles of the continuity equation to measure Qp as RV SV (π[DRVOT/2]2 × VTIRVOT) and Qs as LV SV (π[DLVOT/2]2 × VTILVOT) PVR in Wood units as 10(Peak TR velocity/VTIRVOT ) + 0.16; normal PVR is 0.5 to 1.5 Wood units.

Step 5: Evaluate the Effects of Shunting • In hemodynamically significant shunts, volume overload may result in: • Right atrial enlargement. • Right ventricular enlargement. • Main and branch pulmonary artery (PA) enlargement. • Left atrial enlargement. • The interventricular septum (IVS) may appear flat during diastole. • Right ventricular dilation with paradoxical septal motion may be present.

Ventricular Septal Defect

Small (restrictive) VSDs : when less than half the size of the aortic root and when the LV-RV pressure gradient is greater than 64 mm Hg. Moderately restrictive VSDs are approximately half the size of the root with gradients of approximately 36 mm Hg. With larger nonrestrictive defects, LV and RV systolic pressures are equalized. It is these latter defects that most commonly result in irreversible pulmonary vascular changes (Eisenmenger syndrome).

Membranous (Paramembranous) and Outlet Ventricular Septal Defects Eighty percent of VSDs involve the membranous septum. The jets of membranous and outlet defects appear similar on the parasternal long-axis view, these defects may be distinguished from one another on short-axis views at the level of the great vessels. Membranous defects will be directed toward the septal leaflet of the tricuspid valve (10 to 11 o’clock position on the short-axis clock face Outlet defects will be associated with jets that are directed toward the pulmonic valve Either defect may be accompanied by aortic cusp prolapse and consequent aortic regurgitation.

Inlet Ventricular Septal Defects Inlet defects have been addressed in the preceding discussion of complete atrioventricular canal defects. Although they are often easily detected as in Figure 14-92 (left panel), they may be partially closed by adjacent atrioventricular valve tissue. In such situations, nonstandard views and TEE may be required to detect the ventricular component of the canal defect.

Muscular Ventricular Septal Defects

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