Mitral valve prolapse syndrome: neuro-endocrinological aspects.

Based on analysis of 399 symptomatic patients with mitral valve prolapse (MVP) and the reported experience of others, we developed a clinical classification in order to improve nosology, provide better identification and promote insight into the mechanism of symptoms in patients with MVP. The heading of anatomic MVP designates those in whom symptoms or complications were primarily or directly related to valvular dysfunction and the heading of MVP syndrome designates those patients in whom symptoms cannot be explained on the basis of valvular dysfunction alone. Patients with MVP syndrome present with a symptom complex which results from various forms of neuroendocrine or autonomic dysfunction; the most common symptoms include chest pain, palpitations, cardiac arrhythmias, orthostatic phenomena, syncope, presyncope, fatigue, exercise intolerance, dyspnea and neuropsychiatric symptoms (Table 1). Mechanisms underlying the condition have been shown to include increased adrenergic activity, disturbances of catecholamine regulation, hyperresponsiveness to adrenergic stimulation, anomalous beta-adrenergic receptors, dysfunction of the parasympathetic portion of the autonomic nervous system, disturbances in renin-aldosterone regulation, decreased intravascular volume, diminished left ventricular diastolic volume in the upright position as well as abnormal secretion of atrial natriuretic factor (Table 2). In MVP syndrome, alterations of the heart, kidney, the adrenals and the autonomic nervous system coexist and interact, creating a complex "neuro-endocrine cardiovascular process" which may account for many of the symptoms otherwise unexplained on the basis of the valvular abnormality alone.