Pressure-Volume Relations

The physiologic characterization of an intact ventricular chamber ideally employs analyses yielding integrated functional assessments as well as separate quantification of the major factors (i.e. load, contractility, diastolic function) that determine net performance. More than a century ago, Otto Frank initiated studies to assess ventricular function by relations between chamber pressure and volume, an approach already familiar to 19’ century engineers. In one diagram, both the active and passive filling properties of the pump, its mechano-energetics, and its interaction with vascular loading systems could all be quantified. The pioneering work of Suga, Sagawa and colleagues in the 1970’s, performed in isolated yet physiologically ejecting canine ventricles (1), established the pressure-volume relationship as a powerful means to achieve the major goals of function analysis. Beyond the utility of the end-systolic pressure-volume relationship as a load-independent index of contractility, pressure-volume analysis proved insightful and valuable to both laboratory research and clinical studies (2-3). Recently, this method has been extended by means of miniaturized catheter technology to the mouse (4). The capacity to genetically alter mice combined with in-depth hemodynamic characterization by in-vivo pressure-volume analysis presents unparalleled potential for interfacing molecular science with cardiac systems physiology. This chapter reviews the instrumentation and methods involved in in vivo pressure-volume relation measurement in mice. Cardiovascular physiology of normal mice are compared with published reference human data, and examples from transgenic models are shown to highlight the utility of the method.