Patient-Activated Implantable Drug Delivery System for Treatment of Vasovagal Syncope: A Simple Solution?
Vasovagal events, like many other autonomic nervous system disturbances, have a cyclic and unpredictable course with usually brief periods of symptom recrudescence (so-called “clusters”) alternating with sometimes very long periods of quiescience and asymptomatic status [1, 2]. Thus, chronic therapy with drugs does not appear indicated in the majority of cases and is often associated with serious or intolerable side effects as well as poor patient compliance, especially in young people . Moreover, when events occur, prevention of vasovagal reaction usually requires high drug plasma levels which are difficult to attain through chronic oral administration . Indeed, only occasionally have oral drugs proved to be effective in the few double-blind, randomized, placebo-controlled trials performed to date [5–9]. It is also noteworthy that electrical treatment with a pacemaker, even when useful, rarely leads to complete elimination of symptoms [10, 11], because of the hypotensive effects of the vasodepressor reflex that is practically present in all subjects, generally precedes cardioinhibition and bradycardia  and is not amenable to correction or reversal by cardiac pacing. For all these reasons, it seems logical and desirable to develop an implantable drug delivery system for treatment of vasovagal syncope . Such a device would allow the automatic “on demand” delivery of a bolus of a vasoactive or a cardioactive drug, previously recognized to be effective and safe in preventing tilt-induced syncope, possibly together with the activation of sequential cardiac pacing.
KeywordsDrug Delivery System Cardiac Pace Vasovagal Syncope Placebo Injection Vasovagal Reaction
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