A 5-month-old infant, referred to our institution for percutaneous arterial duct (AD) embolization, showed multiple huge pulmonary arteriovenous malformations (PAVMs) associated with a small AD and several tiny systemic-to-pulmonary collaterals. This anatomic arrangement was a possible cause of lack of cyanosis and disproportionately higher hemodynamic relevance of the ductal shunt. The PAVMs became pathophysiologically evident immediately after the closure of AD and systemic to pulmonary artery collaterals and presented clinically with a life-threatening cyanosis. To improve the patient's clinical and hemodynamic condition, the PAVMs were closed in multiple sittings using a large number of Amplatzer Vascular Plugs (St. Jude Medical Inc., St. Paul, MN, USA). The hemodynamic burden of cardiac malformations resulting in left-to-right shunt may be magnified by the presence of PAVMs as a result of low pulmonary vascular resistance which in turn may completely mask the clinical impact of the latter. Transcatheter approach is life-saving in these complex arrangements.