What is the significance of a step-up in hemodynamics in Atrial Septal Defect (ASD)?

From the Guidelines

A significant step-up in hemodynamics in an atrial septal defect (ASD) is a critical finding that warrants consideration for closure, either via transcatheter device or surgical repair, to prevent long-term complications and improve quality of life. This finding is typically identified during cardiac catheterization, where a measurable increase in oxygen saturation is observed as blood moves from the right atrium to the right ventricle, indicating left-to-right shunting 1. The pulmonary-to-systemic flow ratio (Qp:Qs) is a key metric in assessing the significance of the shunt, with a ratio greater than 1.5:1 suggesting substantial shunting that may require intervention.

Key Considerations

• Patients with significant hemodynamic ASDs often present with symptoms such as fatigue, exercise intolerance, or right heart enlargement, and should be referred for closure 1.
• Even asymptomatic patients with significant shunting should be considered for closure to prevent long-term complications such as right heart failure, pulmonary hypertension, and atrial arrhythmias 1.
• The decision for closure should be made by a multidisciplinary heart team, taking into account the patient's age, ASD size and location, presence of other cardiac abnormalities, and overall health status 1.
• Early intervention in appropriate candidates can prevent irreversible cardiac remodeling and improve long-term outcomes, as evidenced by studies demonstrating improved functional status and reduced risk of atrial arrhythmias after closure 1.

Clinical Implications

• Cardiac catheterization is a crucial diagnostic tool in assessing the hemodynamics of ASD, and may be necessary to determine detailed hemodynamics for decision-making or to clarify discrepant or inconclusive noninvasive imaging data 1.
• The presence of reduced functional capacity, presumed caused by hemodynamically important secundum ASD, is a strong indication for surgical or transcatheter closure 1.
• Older adults should be evaluated for left atrial hypertension resulting from diastolic dysfunction, which may cause similar symptoms but could result in clinical worsening after ASD closure 1.

From the Research

Significance of a Step-up in Hemodynamics in Atrial Septal Defect (ASD)

• A step-up in hemodynamics in ASD is significant as it can lead to complications such as atrial arrhythmia, paradoxical embolization, Eisenmenger's syndrome, pulmonary hypertension, and right ventricular failure if left untreated 2.
• The direction and degree of shunting across the ASD is mainly determined by the difference in compliance between the right and left ventricle, with left-to-right shunting being the most common type 3.
• Hemodynamic assessment of ASD is crucial in determining the significance of the defect and the need for treatment, with diagnostic catheterization usually not indicated unless there is suggestion of pulmonary hypertension on echocardiography 3.
• 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 3.
• Transcatheter device closure has become a standard procedure for treating ASD, with excellent outcomes and minimal complications, especially in adults 4, 5.
• The Amplatzer septal occluder is a commonly used device for transcatheter closure of ASD, with high success rates and low complication rates 2, 5.
• Echocardiography plays a superior role in the precise evaluation of ASD type and suitability for transcatheter device closure 2.