Atrial natriuretic factor and mitral valve prolapse syndrome

Mitral valve prolapse (MVP), is the most frequent valvulopathy, although it is difficult to evaluate its incidence since this pathology is often asymptomatic. However, in some patients a rich variety of symptoms such as chest pain, dyspnea, palpitations, syncope, dizziness, panic attacks and autonomic dysfunctions have been found. The pathogenesis of these symptoms, incompletely understood, appears to be multifactorial, related to altered autonomic function, adrenergic responsiveness and to combinations of these factors. In patients with MVP a variety of neuroendocrine anomalies has been found: high epinephrine and norepinephrine plasma levels, altered rennin-angiotensin-aldosteron (RAA) response to volume depletion and orthostatic stimulation, and high plasma levels of atrial natriuretic factor (ANF) especially in hypovolaemic individuals. The role of ANF could be important in the genesis of MVP syndrome, it could contribute to determine: the imbalance between the sympathetic and parasympathetic system, the altered RAA response to orthostatic stimulus, the volemic and venous flow reductions (with a direct action, other than diuretic and natriuretic action). Factors that can determine ANF secretion abnormality in MVP could be: 1) Mitral regurgitation; 2) increased heart rate and the high incidence, in MVP syndrome, of arrhythmias; 3) central nervous system neuroendocrine imbalance; 4) increased catecholamines secretion.