Single-beat estimation of end-diastolic pressure-volume relationship: A novel method with potential for noninvasive application

Whereas end-systolic and end-diastolic pressure-volume relations (ESPVR, EDPVR) characterize left ventricular (LV) pump properties, clinical utility of these relations has been hampered by the need for invasive measurements over a range of pressure and volumes. We propose a single-beat approach to estimate the whole EDPVR from one measured volume-pressure (V_m and P_m) point. Ex vivo EDPVRs were measured from 80 human hearts of different etiologies (normal, congestive heart failure, left ventricular assist device support). Independent of etiology, when EDPVRs were normalized (EDPVR _n) by appropriate scaling of LV volumes, EDPVR_ns were nearly identical and were optimally described by the relation EDP = A _n·EDV^Bn, with A_n = 28.2 mmHg and B _n = 2.79. V₀ (the volume at the pressure of ∼0 mmHg) was predicted by using the relation V₀ = V_m·(0.6 - 0.006·P_m) and V₃₀ by V₃₀ = V₀ + (V_m,n - V₀)/(P_m/A_n) ^(1/Bn). The entire EDPVR of an individual heart was then predicted by forcing the curve through V_m, P_m, and the predicted V₀ and V₃₀. This technique was applied prospectively to the ex vivo human EDPVRs not used in determining optimal A_n and B_n values and to 36 in vivo human, 12 acute and 14 chronic canine, and 80 in vivo and ex vivo rat studies. The root-mean-square error (RMSE) in pressure between measured and predicted EDPVRs over the range of 0-40 mmHg was <3 mmHg of measured EDPVR in all settings, indicating a good predictive value of this approach. Volume-normalized EDPVRs have a common shape, despite different etiology and species. This allows the entire curve to be predicted by a new method with a potential for noninvasive application. The results are most accurate when applied to groups of hearts rather than to individual hearts.