Infants with hypoplastic left heart syndrome and intact or highly restrictive atrial septum require emergent therapy to relieve pulmonary congestion. Transcatheter stenting has become, in most large centers, the mainstay of therapy for relief of left atrial hypertension. Normally, this procedure is performed with the assistance of transesophageal echocardiographic guidance. However, the transesophageal approach is untenable in neonates of low birth weight, as the transducers can be traumatic and can cause ventilatory difficulty. We present two cases in which transthoracic echocardiographic guidance was used to guide atrial perforation and stenting in low birth-weight neonates with hypoplastic left heart syndrome with intact or highly restrictive atrial septum. Both procedures were straightforward and there were no complications. Real-time biplane imaging greatly assisted in the intervention in one case. The advantages of this approach are discussed.