Relation of papillary muscle traction to autonomic nervous system dysfunction as evaluated by head-up-tilt-test in mitral valve prolapse

ABSTRACT

Mitral valve prolapse [MVP] is one of the commonest valvular abnormalities and is characterized by systolic superior leaflet displacement. This results in abnormal tension on the papillary muscles which may lead to, or is associated with alteration in the autonomic functions. The aim of this work is to detect and assess papillary muscle traction [PMT] in patients with idiopathic MVP in a trial to correlate it with any autonomic dysfunction as evaluated by head-up-tilt test [HUTT]. Thirty symptomatic MVP patients and a control group of 15 persons [cardiologically free], aged 15-35 years, were enrolled in the study. They were all thoroughly evaluated clinically, radiologically, electrocardiographically and by ECHO-Doppler. Patients with secondary causes for MVP were excluded. PMT was measured by 2-dimentional ECHO in all patients and controls who were subsequently subjected to HUTT. The obtained results showed both groups to be comparable. The MVP patients showed mitral regurgitation [MR] in 13 cases [43.3%]. Seventeen patients [56.7%] had MVP with no MR. PMT was greater in patients than in controls [5.7+/-3 versus 0.85+/-0.7mm], p value <0.001. Leaflet displacement as well as PMT index were also significantly higher in patients than in controls [p<0.001]. HUTT was positive [provoking syncope or presyncope associated with hypotension, bradycardia, or both] in six MVP patients [20%] and in none of the controls. HUTT appeared to be predictable by four of the studied parameters, namely, leaflet displacement, PMT, traction index and MR. Ten patients had PMT >/=6mm and 20 patients had it <6mm as shown by ECHO. Six out of the 10 patients who had PMT of >/=6mm had abnormal response to HUTT, while none of the 20 patients with PMT <6mm, and none of the controls had an abnormal response to HUTT. A statistically derived predictor value of >/=6mm PMT should be considered as an indicator to perform HUTT to MVP patients in a trial to detect asymptomatic patients prone to syncope. We recommend that PMT be a part of routine ECHO examination of MVP patients. Those with MR or PMT of 6 mm or more should be evaluated by HUTT for the occurrence of syncope or other manifestations of autonomic dysfunction aiming at avoidance or decrease of morbidity in this group of patients