Introduction

Twin-to-twin transfusion syndrome (TTTS) is a disease of monochorionic, diamniotic twin gestations affecting nearly 20% of monochorionic twin gestations [1, 2]. TTTS is the major cause of death in twin gestations, with a mortality of up to 90% if untreated [3, 4]. Although the initial insult in TTTS results from abnormal placental communications and circulatory derangements between the twins (see Chapter 11.2), we now know that the pathophysiology and clinical manifestations of TTTS are more complex than an imbalance of blood volume between the twin pair. The fundamental circulatory derangement in TTTS results in the release of vasoactive and hormonal mediators that cause a sequence of cardiovascular changes in the donor and recipient twins (see Chapter 11.1). The progression of the cardiovascular disease determines the prognosis and, ultimately, the outcome of the twins. Current treatment strategies are aimed at reversing the underlying origins of the disease in order to improve survival and reduce morbidity. Cardiovascular sequelae strongly influence morbidity and mortality in TTTS, and as such, cardiovascular surveillance is paramount to the understanding and management of this disorder.

In this chapter, our objective is to demonstrate the role of the cardiovascular system as a contributor to the mechanisms of TTTS and the essential role that cardiovascular characterization plays in diagnosing and monitoring the condition. We will review the pathophysiology of TTTS and its impact on the cardiovascular system, current methods for cardiovascular assessment, treatment strategies and the impact these have on the progression of cardiovascular disease, as well as long-term implications.