The majority of the patients are asymptomatic during neonatal and early childhood. Any of the following findings like slow weight gain, tachypnea, or recurrent respiratory infections during infancy should raise suspicion. Most of them are acyanotic; however, very rarely, mild transient cyanosis may happen in the newborn which is due to right-to-left shunt. In physical examination, the precordium is hyperdynamic. Fixed splitting of the second heart sound is heard through respiratory cycles; the severity of pulmonary component of second heart sound (P2) corresponds with the severity of pulmonary hypertension only if it is present. So, the diagnosis in this time domain is usually an incidental finding by echo during routine clinical or paraclinical assessment like looking for the origin of an incidental heart murmur or anything abnormal found in chest X-ray or other studies. Untreated adults have more symptoms and signs, especially related to potential pulmonary hypertension. More explanation regarding adult patients with ASD could be found in Chap. 14 – Anesthetic Management of Adults with Congenital Heart Disease (Andrews et al. 2002; Lammers et al. 2005; Geva et al. 2014; Zvaigzne et al. 2014).

This is an uncommon finding in young ASD patients. However, with increasing age, in those who have been untreated, the frequency of exercise intolerance increases surreptitiously due to aggravation of pulmonary vascular function. If ASD secundum remains unrepaired, exercise capacity will decrease as much as 50–60 % of the predicted values (Geva et al. 2014).

It is not a common finding in neonates and young children; but may be much more frequent in untreated adults. Increasing age and female gender are two main predisposing factors for the occurrence of pulmonary hypertension in untreated ASD; Down syndrome, sleep apnea, and pulmonary vascular embolic events are other risk factors. Eisenmenger syndrome is seen in 5–10 % of untreated adults (Rosas and Attie 2007; Warnes et al. 2008).

It allows both anatomic assessment and, also, the hemodynamic effects of interatrial defects, and it has a great application in sinus venosus ASD. Also, cardiac MR is considered the gold standard in the assessment of RV volume and function and, also, the pulmonary artery and veins. Cardiac MR is the most accurate and the fastest data acquisition modality. However, this technology is not usually used before treatment of ASD secundum and has limited application before treatment of ASD primum (Webb and Gatzoulis 2006; Kharouf et al. 2008; Warnes et al. 2008; Geva et al. 2014).

Especially when using high-resolution cardiac CT, many great data could be acquired; however, the data gained from cardiac CT are not significantly more than the data gained from cardiac MR; also, the risk of radiation in cardiac CT should be considered.

It is not usually indicated to use cardiac catheterization in ASD unless one of the following three (Warnes et al. 2008; Geva et al. 2014):

Using anesthetic drugs with both hemodynamic stability and, also, the capacity to do fast-track extubation seems logic. Also, it is recommended to have an arterial line, a central venous line, and TEE monitoring. Usually, pulmonary artery catheter is not recommended, since it does not increase any data more than TEE. Antibiotic prophylaxis should be considered; Chap. 4 describes fully the antibiotic regime.

(device closure of ASD): although sedation could be used, often general anesthesia and tracheal intubation are preferred since TEE is almost always used for defining the correct deployment of the device and ruling out any residual defect.