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............................................................................................................................................................. non-familial CHD, the recurrence rate varies from 121%,141

according to the underlying lesion. An overview is provided in Table 11. Foetal echocardiography in affected couples is recommended at 1922 weeks gestation and can be done as early as 1516 weeks gestation.

4 Specific lesions

4.1 Atrial septal defect and anomalous

pulmonary venous connection 4.1.1 Introduction and background ASD can remain undiagnosed until adulthood. ASD types include: • Secundum ASD (80% of ASDs; located in the region of the fossa ovalis and its surrounding). • Primum ASD [15%; synonyms: partial AV septal defect [atrioventricular septal defect (AVSD) with communication on the atrial level only], partial AV canal; located near the crux, AV valves are typically malformed, resulting in various degrees of regurgitation (see section 4.3)]. • Superior sinus venosus defect [5%; located near the superior vena cava (SVC) entry, associated with partial or complete connection of right pulmonary veins to SVC/RA]. • Inferior sinus venosus defect [<1%; located near the inferior vena cava (IVC) entry]. • Unroofed coronary sinus [<1%; separation from the left atrium (LA) can be partially or completely missing]. Associated lesions include anomalous pulmonary venous connection, persistent left SVC, pulmonary valve stenosis, and mitral valve prolapse. Interatrial defects are the most frequently associated defects in Ebstein anomaly (see section 4.9). Treatment decisions are more complex in the latter combination. The present section deals with isolated ASD. The shunt volume depends on RV/LV compliance, defect size, and LA/RA pressure. A simple ASD results in LR shunt because of the higher compliance of the RV compared with the LV (relevant shunt in general with defect sizes >_10 mm), and causes RV volume overload and pulmonary overcirculation. Reduction in LV compliance, or any condition with elevation of LA pressure (hypertension, ischaemic heart disease, cardiomyopathy, aortic and mitral valve disease), increases LR shunt. As a consequence, an ASD may become haemodynamically more important with age. Reduced RV compliance (pulmonic stenosis, PAH, other RV disease) or TV disease may decrease LR shunt or eventually cause shunt reversal, resulting in cyanosis.

4.1.2 Clinical presentation and natural history Patients frequently remain asymptomatic until adulthood. However, the majority develop symptoms beyond the fourth decade including reduced functional capacity, exertional shortness of breath, and palpitations (supraventricular tachyarrhythmias), and less frequently pulmonary infections and right heart failure. Life expectancy is reduced overall, but survival is much better than previously assumed.142 PAP can be normal, but on average increases with age. Severe PVD is nevertheless very rare (<5%); its development presumably requires additional factors and the disease course is similar to idiopathic PAH.48 With increasing age, and with increasing PAP, tachyarrhythmias become more common (atrial flutter, AF).143 Systemic embolism may be caused by paradoxical embolism (rare) or AF and atrial flutter.

4.1.3 Diagnostic work-up See section 3.3 for general principles. Key clinical findings include fixed splitting of the second heart sound and a systolic pulmonary flow murmur. ECG typically shows an incomplete right bundle branch block and right-axis deviation (superior left-axis deviation in partial AVSD). An increased pulmonary vascularity on chest X-ray is frequently overlooked. • Echocardiography is the first-line diagnostic technique, providing diagnosis and quantification. RV volume overload, which may be the first unexpected finding in a patient with previously undiagnosed ASD, is the key finding and best characterizes the haemodynamic relevance of the defect (preferable to the shunt ratio). Sinus venosus defects in general require TOE for accurate diagnosis (CMR/CCT is an alternative and superior in case of inferior sinus venosus defects). TOE is also required for precise evaluation of secundum defects before device closure, which should include sizing, exploration of the residual septum’s morphology, the rim size and quality, exclusion of additional defects, and confirmation of a normal pulmonary venous connection. 3D echocardiography provides visualization of ASD morphology. Other key information to be provided includes PAP and tricuspid regurgitation (TR). • CMR is rarely required but may be useful for assessment of RV volume overload, identification of inferior sinus venosus defect, quantification of pulmonary to systemic flow ratio (Qp:Qs), and evaluation of pulmonary venous connection (alternatively for the latter, use CCT). • Cardiac catheterization is required in case of non-invasive signs of PAP elevation (calculated systolic PAP >40 mmHg or indirect signs when PAP cannot be estimated) to determine PVR. • Exercise testing should be performed in patients with PAH to exclude desaturation.

4.1.4 Surgical/catheter interventional treatment Indications for intervention are summarized in the Recommendations for intervention in atrial septal defect (native and residual) table and in Figure 2. Surgical repair has low mortality (<1% in patients without significant comorbidity) and good long-term outcome when performed early (childhood, adolescence) and in the absence of PH.144,145 Although surgical repair can be performed with very low risk, even in the elderly, comorbidities that may affect operative risk need to be considered and then risk weighed against potential benefit. Downloaded from academic.oup.com/eurheartj/article/42/6/563/5898606 by guest on 07 October 2026