Conductance, admittance, and hypertonic saline: should we take ventricular volume measurements with a grain of salt?

摘要

Undoubtedly the most comprehensive way to assess contractile function of the heart relies on pressure-volume relationships, often called pressure-volume loops. Originally established in the canine model by Sagawa and coworkers, pressure-volume relationships allow us to determine indexes of ventricular performance that are independent of loading conditions and heart rate such as preload-recruitable stroke work (PRSW), end-systolic chamber stiffness (Ees or Emax), diastolic function (EDPVR), and load-independent contractility as derived from the dP/dmiax end-diastolic volume relation (2, 7). All these indexes require simultaneous recordings of left ventricular volumes and intraventricular pressures in vivo. Although more easily achievable in large animals and humans, real-time volume measurements in mouse hearts remain challenging.