The role of mitral regurgitation in the neurovegetative regulation of mitral valve prolapse

To define the role of mitral regurgitation (MR) on sympatho-vagal balance in mitral valve prolapse (MVP) patients, we analyzed 41 ambulatory MVP symptomatic patients. Twenty-seven patients (4 males, 23 females, aged 34 +/- 3 years) had significative MR assessed color Doppler, while 14 patients (5 males, 9 females, aged 29 +/- 3 years) had no MR; 36 age- and sex-matched subjects were studied as controls (C). Spectral analysis of heart rate variability (HRV) was performed at rest and during sympathetic activation (tilt). In the whole group of MVP patients spectral components did not differ significantly from C at rest and during tilt. When patients were subdivided in relation to the presence (+) or absence (-) of MR, HRV revealed in MR+ patients at rest an increased high frequency (HF) and a diminished low frequency (LF) component (47 +/- 5 and 41 +/- 5 normalized units, nu) with respect to C (34 +/- 3 and 54 +/- 3 nu, p < 0.05, respectively). Viceversa during tilt, in MR+ patients it was possible to observe a LF increase greater than in C (delta LF: 36 +/- 4 versus 25 +/- 3 nu, p < 0.05). As HF component is currently interpreted as a marker of vagal modulation of HRV, our results suggest an increased vagal tone associated with MR possibly due to stimulation of atrial vagal receptors; moreover, an increased sympathetic responsiveness to tilt seems to characterize MR+ patients.