Hemodynamic instability in the transitional period after birth.

It is not uncommon for a patient to experience hemodynamic instability following birth. This is due to the fact that the transitional period requires dramatic cardiorespiratory changes. When it goes well, improved lung compliance and successful transition to the postnatal circulation is seen. However, it is highly beneficial that clinicians have a solid understanding of all of the required changes, the unique aspects of the neonatal myocardium, and the influence of cardiovascular disease on normal adaptive mechanisms. In this manuscript, we will review the physiology of the normal postnatal circulatory adaptation, the unique characteristics of the neonatal myocardium and how it behaves in states of altered loading conditions, and the impact of hemodynamic disease states on health and wellbeing during the immediate postnatal time-period.