The importance of right ventricular dysfunction, as a driver of symptoms and outcomes in the normal biventricular circulation, is increasingly recognized. However, the pathophysiologic mechanisms underlying the role of the right ventricle in acute and chronic hemodynamic deterioration are less well understood. This review aims to clarify the impact of acute right ventricular dysfunction on biventricular interactions and, in turn, to discuss the role of cardiopulmonary interactions in the normal circulation and when modified by the presence of associated structural malformations. Such interactions may be adverse or beneficial, and a more complete understanding of their importance may result in novel therapeutic strategies and improved outcomes.
It is becoming increasingly recognized that right ventricular dysfunction plays a crucial role in many cardiovascular diseases. Even in traditionally “left heart” diseases such as dilated cardiomyopathy, the impact of right ventricular dysfunction on mortality is now well established.1 It would be surprising, therefore, if the right ventricle (RV) did not play a similarly important role in congenital heart disease. Many congenital heart diseases are characterized by primary abnormalities of right ventricular structure and function, and while “corrective” surgery often restores the heart to a functionally “normal” biventricular circuit, right ventricular hemodynamics are often far from normal. Indeed, the RV frequently remains exposed to highly abnormal loading conditions and is subject to the additional impact of adverse electromechanical, mechanoelectric, and cardiopulmonary interactions.
Consequently, assessment of right ventricular function in congenital heart disease is just as important, if not more so, in the congenitally malformed heart as it is in the otherwise structurally normal heart. In many ways, however, it is more difficult, because the unusual, and sometimes unique, hemodynamics in the congenitally malformed heart challenge the validity of many of the techniques available for assessment. Conversely, congenital heart disease provides us with “natural models” of abnormal right ventricular loading that are difficult to produce in animal models. There is therefore a unique opportunity to better understand right ventricular dysfunction as it is affected by such abnormalities. It is beyond the scope of this review to discuss the impact of the hundreds of different congenital heart malformations and the detailed results of their treatment, particularly when the RV functions as the systemic ventricle. Instead, this review will focus on more general considerations of systolic and diastolic dysfunction in the congenitally malformed subpulmonary RV, especially as it pertains to early postoperative outcomes.