"Heart of the Matter": Cardiac Dysfunction in Congenital Diaphragmatic Hernia.

Despite advances in caring for neonates with congenital diaphragmatic hernia (CDH), mortality and morbidity continues to be high. Additionally, the pathophysiology of cardiac dysfunction in this condition is poorly understood. Postnatal cardiac dysfunction in neonates with CDH may be multifactorial with origins in fetal life. Mechanical obstruction, competition from herniated abdominal organs into thoracic cavity combined with redirection of ductus venosus flow away from patent foramen ovale leading to smaller left-sided structures may be a contributing factor. This shunting decreases left atrial and left ventricular blood volume which may result in altered micro- and macro- vascular aberrations affecting cardiac development in the prenatal period. Direct mass effect from herniated intra-abdominal contents restricting cardiac growth, and/or reduced left ventricular preload may contribute independently to left ventricular dysfunction in the absence of right ventricular dysfunction and or pulmonary hypertension. With variable clinical phenotypes of cardiac dysfunction, pulmonary hypertension, and respiratory failure in patients with CDH, there is increased need for individualized diagnosis and tailored therapy. Routine use of therapy such as inhaled nitric oxide (iNO) and sildenafil which induces significant pulmonary vasodilation may be detrimental in LV dysfunction whereas in a patient with pure RV dysfunction, they may be beneficial. Targeted functional echocardiography serves as a real time tool for defining the pathophysiology and aids optimization of vasoactive therapy in affected neonates.