Submitted on November 23, 2005
Accepted on January 12, 2006
Single Beat Estimation of theEnd-Diastolic Pressure-Volume Relationship A Novel Method with the Potential for Noninvasive Application
Stefan Klotz1*, Ilan Hay1, Marc L Dickstein2, Geng-Hua Yi1, Jie Wang1, Mathew M Maurer1, David A Kass3, and Daniel Burkhoff1
1 Medicine, Columbia University, New York, NY, USA
2 Anesthesiology, Columbia University, New York, NY, USA
3 Medicine, John Hopkins Medical Institutions, Baltimore, MD, USA
* To whom correspondence should be addressed. E-mail: stefan.klotz{at}ukmuenster.de.
Background: While end-systolic and end-diastolic pressure-volume relations (ESPVR, EDPVR) characterize 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 (Vm, Pm) point.
Methods and Results: Ex vivo EDPVRs were measured from 80 human hearts of different etiologies (Normal, CHF, LVAD support). Independent of etiology, when EDPVR were normalized (EDPVRn) by appropriate scaling of LV volumes, EDPVRn's were nearly identical and were optimally described by the relation EDP = An.EDVBn, with An=28.2 mmHg and Bn=2.79. V0 (the volume at the pressure of ~0 mmHg) was predicted using the relation V0=Vm.(0.6-0.006.Pm) and V30 by V30=V0+(Vm,n-V0)/(Pm/An)(1/Bn). The entire EDPVR of an individual heart was then predicted by forcing the curve through Vm, Pm and the predicted V0 and V30. This technique was applied prospectively to the ex vivo human EDPVRs not used in determining optimal An and Bn 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 less than 3 mmHg of measured EDPVR in all settings indicating good predictive value of this approach.
Conclusion: 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 non-invasive application. The results are most accurate when applied to groups of hearts rather than to individual hearts.
