Changes in systemic sympathetic nervous system activity after mitral valve surgery and their relationship to changes in left ventricular size and systolic performance in patients with mitral regurgitation.
BACKGROUND
We have shown that the systemic sympathetic nervous system (SNS) is activated in patients with chronic mitral regurgitation (MR). However, the fate of systemic SNS activity after surgical correction of MR is currently unknown.


METHODS
We examined 14 patients with MR who had normal sinus rhythm with an investigational, preoperative cardiac catheterization, including arterial norepinephrine (NE) sampling and [(3)H]-NE infusions and arterial blood sampling to determine NE kinetic parameters using a 2-compartment modeling analysis. The arterial NE and NE kinetic parameters were determined in all patients after mitral valve surgery (MVS) at a mean of 12 months. A 2-dimensional echocardiographic examination was also performed before and after MVS.


RESULTS
The average extravascular NE release rates (NE(2)) before and after MVS were 1.89 +/- 0.66 and 2.26 +/- 0.82 microg/min/m(2) (P =.24), respectively. The average left ventricular (LV) end-diastolic dimension, fractional shortening, and ejection fraction decreased, whereas the mean LV end-systolic dimension did not change between the pre- and post-MVS echocardiographic studies. However, these group averages were comprised of patients with MR in whom the NE(2) and echocardiographic values both increased and decreased. This lack of homogeneity was a reflection of our new observation that the pre- to post-MVS changes in NE(2) were directly proportional to the changes in LV end-systolic dimension (r = 0.91, P <.001) and inversely related to the changes in LV fractional shortening (r = -0.82, P <.001) and ejection fraction (r = -0.78, P <.001).


CONCLUSIONS
The response in systemic SNS activity in patients with MR after MVS is not homogeneous, and these changes are concordant with the post-MVS changes in LV size and systolic performance. These data further support our earlier observations and extend them to suggest that systemic SNS activation in patients with chronic MR is related to LV remodeling and impaired systolic performance.
Mehta
Rajendra H
RH
University of Michigan and Veterans Affairs, Healthcare Systems, Ann Arbor, MI, USA. rmehta@umich.edu
Supiano
Mark A
MA
Grossman
P Michael
PM
Oral
Hakan
H
Montgomery
Daniel G
DG
Briesmiester
Kerri A
KA
Smith
Marla J
MJ
Starling
Mark R
MR
D000328:Adult; D000368:Aged; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008943:Mitral Valve / Q000601:surgery*; D008944:Mitral Valve Insufficiency / Q000503:physiopathology* / Q000601:surgery*; D009638:Norepinephrine / Q000378:metabolism; D013318:Stroke Volume; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D013599:Systole; D014463:Ultrasonography; D016277:Ventricular Function, Left / Q000502:physiology*
D009638:Norepinephrine