The Impact of an Atrial Septal Defect on Hemodynamics in Patients With Heart Failure

Abstract

Access at: www.USCjournal.comPulmonary venous hypertension and congestion that occurs with left ventricular (LV) failure is generally not seen in the presence of a large atrial septal defect (ASD). As long as right ventricular (RV) function and distensibility are not impaired, the ASD provides an alternate pathway for atrial emptying, thus preventing or attenuating elevated LV filling pressures.When RV dysfunction develops and right atrial pressure increases, this 'protective' effect of the ASD is reduced, the left to right shunt flow declines, and the LV filling pressures increase. [1][2][3][4][5][6] These observations indicate that the hemodynamic consequences of ASD closure (or the creation of an ASD) are influenced by the functional state and the interaction of the two ventricles. In this brief review, we emphasize pulmonary venous, left atrial (LA), and LV diastolic pressures, and consider the impact of an ASD on the hemodynamics of heart failure. Closure of an Atrial Septal DefectSymptomatic patients with uncomplicated ASD generally show an improvement in functional capacity after closure of an ASD. However, some patients require special consideration. For example, in the presence of an abnormal left ventricle, closure of an ASD removes its protective effect, and contributes to the poor clinical outcome that is occasionally seen. 4,5 A modest increment in LA pressure is often seen after closure of an ASD, but large changes in pressure are uncommon and seen primarily in older patients with hypertension and/or LV dysfunction. 5,7-10 Before proceeding with ASD closure in such patients, consideration should be given to test occlusion of the ASD to evaluate the potential for a deleterious increase in LA pressure.An example of the effect of ASD closure in a patient with RV and LV dysfunction and mitral stenosis (valve area = 1.1 cm 2 ) is shown in Figure 1. Transient occlusion of the ASD resulted in an increase in pulmonary capillary wedge pressure (PCWP) from 18 to 23 mmHg.The increase developed gradually over several minutes, stabilizing after 3 minutes. The pressure returned to baseline after removal of the occluding balloon catheter. Some authorities suggest that an LA pressure increase exceeding 3 mmHg during test occlusion should prompt a consideration of the use of a fenestrated occluder that reduces, but does not abolish, the left-toright interatrial shunt. 7 This approach should decrease the shunt flow and reduce the volume load on the right heart, and would potentially provide a lower LA pressure than would be expected with a complete closure. 9Others use an LA pressure increment of 10 mmHg (during test occlusion) to identify high-risk patients. 8 Test occlusion of the ASD in patients at risk of a significant increment in LA pressure is relatively easy to recommend, but the exact partition pressure that would optimally identify patients who might benefit from a fenestrated occluder is not known. Creation of an Atrial Septal Defect as a Therapeutic MeasureIn 1948 Harkin and associates recognized the infr...

Acute-onset heart failure secondary to biventricular non-compaction cardiomyopathy and atrial septal defect in a woman presenting in the seventh decade

“…As highlighted by Shah et al , ASD provides an alternate pathway for left atrial emptying and provides alleviation of elevated left-sided pressures. However, this compensatory effect reverses in case of RV dysfunction and warrants ASD closure 10. This was the case in our patient, where the haemodynamic equilibrium was breached which caused her biventricular failure.…”

Comparison of the Change in Diastolic Dysfunction after Transcatheter Atrial Septal Defect Closure between Asymptomatic Younger and Older Age Groups

“…In patients presenting with senile LV dysfunction, left-to-right shunt in ASD could offer another inter-atrial route for LA flow instead of LV filling, and mask the abnormal increase of LA pressure and LV filling pressure [ 7 ]. Therefore, in these patients, ASD closure can increase the LV diastolic and LV filling pressures in the enlarged, volume-loaded left heart.…”

“…Moreover, even asymptomatic patients exhibited a similar diastolic function change after ASD closure, without presenting with any cardiac function deterioration patterns before diagnosis. We believe that ASD closure in elderly patients with suspected or existing LV or RV dysfunction should be performed only after a meticulous consideration of the hemodynamic benefits and risks of closure [ 7 , 19 ].…”