Cardiac performance depends on a wide variety of factors, of which preload, afterload, heart rate, and contractility are the best recognised (Fig. 1.1). However, other factors play important roles but are less acknowledged. The diastolic ventricular interaction (DVI) and its impact on preload, the preload recruitable stroke-work, ventriculo-arterial coupling and other vascular and ventricular properties, through their interaction at end-systole, all have signifcant influence on cardiac performance.