Presentation of preload and afterload to isolated heart preparations

The isolated heart preparation has been the fundamental model for performing mechanical and energetics investigations of cardiac function. Numerous reviews have been conducted detailing the evolution and development of Langendorff-heart and working-heart models, as well as considerations of experimental factors, including perfusion techniques, experimental conditions and applications in both preclinical and clinical areas. In this review, we provide the first narration and collection of the various techniques applied to load isolated heart preparations. Specifically, we describe how preload and afterload are presented, controlled and changed, either physically or using software, to prescribe pressure or flow impedance to the isolated heart. We also discuss the modelling of in vivo haemodynamics and how these conditions can be visualised in a working-heart model. We complete the review by offering future perspectives on developing working-heart models that not only aim to address the limitations of the current set-ups but also extend to a dynamic impedance afterload device that can adapt beat-by-beat impedance changes, mimicking the in vivo condition more accurately.