Adenosine hypersensitivity and atrioventricular block.

Area of Science:

• Cardiovascular Physiology
• Neuroscience
• Clinical Medicine

Background:

• Adenosine is a ubiquitous endogenous compound with significant cardiovascular effects, including cardioinhibition and vasodilation.
• Adenosine plays a crucial role as a modulator in various forms of syncope, a condition characterized by transient loss of consciousness.

Purpose of the Study:

• To investigate the correlation between distinct plasma adenosine levels and specific clinical presentations of syncope.
• To explore the pathophysiological classification of syncope based on purinergic profiles and its potential therapeutic implications.

Main Methods:

• Analysis of plasma adenosine levels in patients presenting with syncope.
• Correlation of purinergic profiles with clinical manifestations, including heart rhythm, prodromes, and vasodilation/vasodepression.
• Classification of patients into 'low-adenosine' and 'high-adenosine' groups based on their adenosine levels.

Main Results:

• Patients with chronically low plasma adenosine levels ('low-adenosine patients') are prone to asystole, often presenting with idiopathic atrioventricular block or carotid sinus syndrome.
• Patients with chronically high plasma adenosine levels ('high-adenosine patients') are prone to vasodilation, typically experiencing vasovagal syncope.
• Distinct purinergic profiles were significantly correlated with specific syncope presentations and underlying mechanisms.

Conclusions:

• Plasma adenosine levels are critical determinants in the pathophysiology of different syncope types.
• A pathophysiological classification based on adenosine levels ('low-adenosine' vs. 'high-adenosine') offers a novel framework for understanding syncope.
• This classification holds potential for guiding targeted therapeutic strategies in syncope management.