title: Relation between pressure and volume unloading during ramp testing in patients supported with a continuous-flow left ventricular assist device.
abstract: Pulmonary capillary wedge pressure (PCWP) is the key to describing left ventricular (LV) unloading; however, the relation between pressure and the echocardiography-derived surrogate of LV volume (LV end-diastolic diameter [LVEDD]) as a function of pump speed (revolutions per minute [RPM]) in continuous-flow LV assist device (CF-LVAD) patients is unknown. In this study, the pressure-volume relation as a function of RPM during ramp testing was investigated by simultaneously measuring PCWP by Swan-Ganz catheter and LVEDD by echocardiography. The ramp protocol started at usual pump setting (ramp-base) and then went from 8,000 RPM (ramp-low) increasing by 400 RPM/5 minutes until reaching 12,000 RPM or suction/arrhythmic event (ramp-high). The study was finalized by a 25 Watt exercise test at two ramp steps. Ten patients with ramp-base of 9,300 ± 241 RPM (at which 3 of 10 had aortic valve opening) were examined. At ramp-low, ramp-base, and ramp-high, PCWP was 20 ± 4, 14 ± 4, and 7 ± 3 mm Hg (p < 0.001 for all comparisons) and LVEDD 6.6 ± 1.0, 6.7 ± 0.9, and 5.5 ± 1.7 cm (p < 0.05 for all comparisons but ramp-low versus ramp-base). Correlation between PCWP and LVEDD slopes; R = 0.53 (p = 0.02). In conclusion, PCWP as a function of RPM is weakly correlated with changes in LVEDD. Thus, LVEDD is not an accurate measure of unloading in CF-LVAD patients.
authors.affiliation: From the *Department of Cardiology, Rigshospitalet, Copenhagen, Denmark; and †Department of Cardiology, Johns Hopkins Hospital, Baltimore, Maryland.
authors.forename: Mette H
authors.initials: MH
authors.lastname: Jung
authors.forename: Christian
authors.initials: C
authors.lastname: Hassager
authors.forename: Louise
authors.initials: L
authors.lastname: Balling
authors.forename: Stuart D
authors.initials: SD
authors.lastname: Russell
authors.forename: Soeren
authors.initials: S
authors.lastname: Boesgaard
authors.forename: Finn
authors.initials: F
authors.lastname: Gustafsson
mesh_terms: D004452:Echocardiography; D005260:Female; D006333:Heart Failure / Q000601:surgery; D006352:Heart Ventricles / Q000503:physiopathology*; D006353:Heart-Assist Devices; D006801:Humans; D008297:Male; D008875:Middle Aged; D011669:Pulmonary Wedge Pressure / Q000502:physiology*