Hemodynamic assessment of atrial septal defects

Abstract

Atrial septal defect (ASD) is one of the most common congenital cardiac anomalies. ASD can present as an isolated lesion in an otherwise normal heart or in association with other congenital heart conditions. Regardless of the type of ASD, the direction and degree of shunting across the communication is mainly determined by the difference in compliance between the right and left ventricle. Hemodynamics in children is characterized by left-to-right shunting, dilated right heart structures and normal pulmonary artery pressures (PAP). Patients diagnosed at adult age often present with complications related to long-standing volume overload such as pulmonary artery hypertension and right and left ventricular dysfunction. Diagnostic catheterization is usually not indicated unless there is suggestion of pulmonary hypertension on echocardiography. In older patients and/or in those with ventricular dysfunction, measurement of left heart pressures during temporary balloon occlusion is recommended prior to device closure as it may not be tolerated. In ASD associated with other congenital malformations, shunting degree and direction will depend upon underlying condition. Restrictive ASD can result in significant hemodynamic compromise in neonates with conditions such as hypoplastic left heart syndrome (HLHS) and transposition of the great arteries (TGA). In most cases, hemodynamics can be estimated with echocardiography only.

Keywords: Atrial septal defect (ASD); congenital heart disease; hemodynamics.

Figure 1

Simultaneous pulmonary artery pressure (PAP) tracing and transesophageal echocardiogram (TEE) performed in a patient with pulmonary hypertension and ASD at baseline (A, top figures), and during administration of pulmonary vasodilators (B, bottom figures). (A) Shows PAP tracing consistent with pulmonary hypertension and right-to-left shunting across the ASD; (B) shows reversal of flow (left-to-right) on TEE associated with a drop in PAP. LA, left atrium; RA, right atrium.

Figure 2

Change on left ventricular end diastolic pressure (LVEDP) during balloon occlusion of ASD on a 15-year-old patient with LV diastolic dysfunction. (A) LV tracing at baseline shows an end diastolic pressure of around 10–12 mmHg; (B) balloon occlusion of ASD; (C) LV tracing during ASD balloon occlusion shows an increase on the LVEDP to 22–25 mmHg. LA, left atrium; RA, right atrium; LV, left ventricle.