Compared with control subjects, the systemic sympathetic nervous system is activated in patients with mitral regurgitation.
BACKGROUND
Whether the systemic sympathetic nervous system is activated as a compensatory mechanism in response to mitral regurgitation (MR) in humans is unknown. We tested the hypotheses that the systemic sympathetic nervous system would be activated in patients with MR in comparison with control subjects and that this activation would occur early in the disease process as a compensatory mechanism for chronic left ventricular (LV) volume overload.


METHODS
We studied 37 patients with MR who underwent right heart catheterization and biplane cineventriculography to obtain LV end-diastolic and end-systolic volumes, ejection fractions, and regurgitant volumes. In these 37 patients with MR and in 23 control subjects, an [(3)H]-norepinephrine ([(3)H]-NE) infusion and multiple arterial blood samples provided data for a 2-compartment modeling analysis to calculate extravascular NE release rates (NE(2)).


RESULTS
The mean NE(2) (2.05 +/- 0.76 microg/min/m(2)) in the patients with MR was greater than that in the control subjects (1.48 +/- 0.75 microg/min/m(2), P =.007). Furthermore, the mean NE(2) values were also greater in the patients with MR who were in clinical class I (P =.05), with a pulmonary capillary wedge pressure <12 mm Hg (P =.05) or a LV ejection fraction >or=0.60 (P =.06) compared with the control subjects. The mean NE(2) values were increased further in patients with MR who had a LV ejection fraction <0.60 (P =.02).


CONCLUSIONS
The systemic sympathetic nervous system is activated in patients with MR in comparison with control subjects, and this activation appears to occur early in the disease process as a compensatory mechanism for LV volume overload.
Mehta
Rajendra H
RH
TOP University of Michigan and Veterans Affairs Healthcare Systems, Ann Arbor, USA.
Supiano
Mark A
MA
Oral
Hakan
H
Grossman
P Michael
PM
Montgomery
Daniel S
DS
Smith
Marla J
MJ
Starling
Mark R
MR
D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D006328:Cardiac Catheterization; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D008875:Middle Aged; D008944:Mitral Valve Insufficiency / Q000378:metabolism / Q000503:physiopathology*; D009638:Norepinephrine / Q000378:metabolism* / Q000493:pharmacokinetics; D011859:Radiography; D018709:Statistics, Nonparametric; D013564:Sympathetic Nervous System / Q000378:metabolism / Q000503:physiopathology*; D013566:Sympathomimetics / Q000493:pharmacokinetics
D013566:Sympathomimetics; D009638:Norepinephrine