Restoration of Pulsatile Flow Reduces Sympathetic Nerve Activity Among Individuals With Continuous-Flow Left Ventricular Assist Devices.
BACKGROUND
Current-generation left ventricular assist devices provide circulatory support that is minimally or entirely nonpulsatile and are associated with marked increases in muscle sympathetic nerve activity (MSNA), likely through a baroreceptor-mediated pathway. We sought to determine whether the restoration of pulsatile flow through modulations in pump speed would reduce MSNA through the arterial baroreceptor reflex.


RESULTS
Ten men and 3 women (54 ± 14 years) with Heartmate II continuous-flow left ventricular assist devices underwent hemodynamic and sympathetic neural assessment. Beat-to-beat blood pressure, carotid ultrasonography at the level of the arterial baroreceptors, and MSNA via microneurography were continuously recorded to determine steady-state responses to step changes (200-400 revolutions per minute) in continuous-flow left ventricular assist device pump speed from a maximum of 10,480 ± 315 revolutions per minute to a minimum of 8500 ± 380 revolutions per minute. Reductions in pump speed led to increases in pulse pressure (high versus low speed: 17 ± 7 versus 26 ± 12 mm Hg; P<0.01), distension of the carotid artery, and carotid arterial wall tension (P<0.05 for all measures). In addition, MSNA was reduced (high versus low speed: 41 ± 15 versus 33 ± 16 bursts per minute; P<0.01) despite a reduction in mean arterial pressure and was inversely related to pulse pressure (P=0.037).


CONCLUSIONS
Among subjects with continuous-flow left ventricular assist devices, the restoration of pulsatile flow through modulations in pump speed leads to increased distortion of the arterial baroreceptors with a subsequent decline in MSNA. Additional study is needed to determine whether reduction of MSNA in this setting leads to improved outcomes.
From Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas (W.K.C., T.T., A.S., J.L., M.R., R.P., Q.F., B.D.L.); Division of Cardiology, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas (W.K.C., C.F., J.K., C.A., M.H.D., B.D.L.); and Division of Cardiology, Department of Medicine, Emory University, Atlanta, GA (D.M.).
William K
WK
Cornwell
From Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas (W.K.C., T.T., A.S., J.L., M.R., R.P., Q.F., B.D.L.); Division of Cardiology, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas (W.K.C., C.F., J.K., C.A., M.H.D., B.D.L.); and Division of Cardiology, Department of Medicine, Emory University, Atlanta, GA (D.M.).
Takashi
T
Tarumi
From Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas (W.K.C., T.T., A.S., J.L., M.R., R.P., Q.F., B.D.L.); Division of Cardiology, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas (W.K.C., C.F., J.K., C.A., M.H.D., B.D.L.); and Division of Cardiology, Department of Medicine, Emory University, Atlanta, GA (D.M.).
Abigail
A
Stickford
From Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas (W.K.C., T.T., A.S., J.L., M.R., R.P., Q.F., B.D.L.); Division of Cardiology, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas (W.K.C., C.F., J.K., C.A., M.H.D., B.D.L.); and Division of Cardiology, Department of Medicine, Emory University, Atlanta, GA (D.M.).
Justin
J
Lawley
From Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas (W.K.C., T.T., A.S., J.L., M.R., R.P., Q.F., B.D.L.); Division of Cardiology, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas (W.K.C., C.F., J.K., C.A., M.H.D., B.D.L.); and Division of Cardiology, Department of Medicine, Emory University, Atlanta, GA (D.M.).
Monique
M
Roberts
From Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas (W.K.C., T.T., A.S., J.L., M.R., R.P., Q.F., B.D.L.); Division of Cardiology, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas (W.K.C., C.F., J.K., C.A., M.H.D., B.D.L.); and Division of Cardiology, Department of Medicine, Emory University, Atlanta, GA (D.M.).
Rosemary
R
Parker
From Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas (W.K.C., T.T., A.S., J.L., M.R., R.P., Q.F., B.D.L.); Division of Cardiology, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas (W.K.C., C.F., J.K., C.A., M.H.D., B.D.L.); and Division of Cardiology, Department of Medicine, Emory University, Atlanta, GA (D.M.).
Catherine
C
Fitzsimmons
From Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas (W.K.C., T.T., A.S., J.L., M.R., R.P., Q.F., B.D.L.); Division of Cardiology, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas (W.K.C., C.F., J.K., C.A., M.H.D., B.D.L.); and Division of Cardiology, Department of Medicine, Emory University, Atlanta, GA (D.M.).
Julius
J
Kibe
From Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas (W.K.C., T.T., A.S., J.L., M.R., R.P., Q.F., B.D.L.); Division of Cardiology, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas (W.K.C., C.F., J.K., C.A., M.H.D., B.D.L.); and Division of Cardiology, Department of Medicine, Emory University, Atlanta, GA (D.M.).
Colby
C
Ayers
From Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas (W.K.C., T.T., A.S., J.L., M.R., R.P., Q.F., B.D.L.); Division of Cardiology, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas (W.K.C., C.F., J.K., C.A., M.H.D., B.D.L.); and Division of Cardiology, Department of Medicine, Emory University, Atlanta, GA (D.M.).
David
D
Markham
From Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas (W.K.C., T.T., A.S., J.L., M.R., R.P., Q.F., B.D.L.); Division of Cardiology, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas (W.K.C., C.F., J.K., C.A., M.H.D., B.D.L.); and Division of Cardiology, Department of Medicine, Emory University, Atlanta, GA (D.M.).
Mark H
MH
Drazner
From Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas (W.K.C., T.T., A.S., J.L., M.R., R.P., Q.F., B.D.L.); Division of Cardiology, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas (W.K.C., C.F., J.K., C.A., M.H.D., B.D.L.); and Division of Cardiology, Department of Medicine, Emory University, Atlanta, GA (D.M.).
Qi
Q
Fu
From Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas (W.K.C., T.T., A.S., J.L., M.R., R.P., Q.F., B.D.L.); Division of Cardiology, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas (W.K.C., C.F., J.K., C.A., M.H.D., B.D.L.); and Division of Cardiology, Department of Medicine, Emory University, Atlanta, GA (D.M.).
Benjamin D
BD
Levine
D000328:Adult; D000368:Aged; D017704:Baroreflex / Q000502:physiology*; D005260:Female; D006353:Heart-Assist Devices / Q000639:trends; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011311:Pressoreceptors / Q000502:physiology*; D011673:Pulsatile Flow / Q000502:physiology*; D013564:Sympathetic Nervous System / Q000502:physiology; D016277:Ventricular Function, Left / Q000502:physiology*
blood pressure; heart failure; pressoreceptors; sympathetic nervous system; ventricular assist device