ABSTRACT
Mitral stenosis [MS] may increase sympathetic nervous activity by increasing left atrial pressure and decreasing cardiac output. Consequently, increased sympathetic nervous activity may be a risk factor for the development of clinical manifestations and complications of mitral stenosis. Thus, we aimed in this study to assess the sympathetic nervous activity in patients with rheumatic mitral stenosis using heart rate variability analysis and to define factors affecting autonomic function in those patients. The study was conducted upon thirty-one consecutive patients with rheumatic mitral stenosis in sinus rhythm attending cardiology outpatient clinics and another thirty-one normal controls matched for age and gender, and continued from April-2005 until April-2006. Heart rate variability [HRV] analysis was performed in both groups; with full clinical and echocardiographic assessment performed in mitral stenosis patients. Mean N-N interval [Mean NN], standard deviation of all N-N intervals [SDNN], number of N-N intervals that differ by more than 50 milliseconds from adjacent interval divided by the total number of all N-N intervals [PNN50], and high frequency power [HF] were lower; and low frequency power [LF] and low frequency-to-high frequency ratio [LF/HF ratio] were higher in patients with mitral stenosis as compared to their normal counterparts. HRV parameters favoring sympathetic overactivity were found to be significantly correlated to a tighter mitral valve area, higher mean trans-mitral gradient, wider left atrial diameter, higher systolic pulmonary arterial pressure, increased severity of dyspnea and overall duration of patients' symptoms. Thus, sympathetic nervous activity is increased in patients with mitral stenosis and sympathetic overactivity worsens their symptoms. Most significant factors that affect autonomic function in those patients are mitral valve area, mean transmitral gradient, left atrial diameter, and systolic pulmonary arterial pressure