Reversible postural orthostatic tachycardia syndrome

Clinical and Laboratory Improvement in Hyperadrenergic Postural Orthostatic Tachycardia Syndrome (POTS) after COVID-19 Infection

A 32-year-old woman with a history of symptomatic supraventricular tachycardia, inappropriate sinus tachycardia, and hyperadrenergic POTS was treated with ivabradine and metoprolol. She then presented with bradycardia and Mobitz II second-degree AV block on event monitoring six weeks after COVID-19 infection. Her post-viral workup revealed normalization of catecholamine levels and significant symptomatic improvement in heart rate. To the authors' knowledge, this is the first reported case of improvement in POTS after COVID-19 infection. As our understanding of COVID-19 continues to improve, it will be vital to better understand the impact of COVID-19 dysautonomia on cardiac patients.

How fast monoamine oxidases decompose adrenaline? Kinetics of isoenzymes A and B evaluated by empirical valence bond simulation

This work scrutinizes kinetics of decomposition of adrenaline catalyzed by monoamine oxidase (MAO) A and B enzymes, a process controlling the levels of adrenaline in the central nervous system and other tissues. Experimental kinetic data for MAO A and B catalyzed decomposition of adrenaline are reported only in the form of the maximum reaction rate. Therefore, we estimated the experimental free energy barriers form the kinetic data of closely related systems using regression method, as was done in our previous study. By using multiscale simulation on the Empirical Valence Bond (EVB) level, we studied the chemical reactivity of the MAO A catalyzed decomposition of adrenaline and we obtained a value of activation free energy of 17.3 ± 0.4 kcal/mol. The corresponding value for MAO B is 15.7 ± 0.7 kcal/mol. Both values are in good agreement with the estimated experimental barriers of 16.6 and 16.0 kcal/mol for MAO A and MAO B, respectively. The fact that we reproduced the kinetic data and preferential catalytic effect of MAO B over MAO A gives additional support to the validity of the proposed hydride transfer mechanism. Furthermore, we demonstrate that adrenaline is preferably involved in the reaction in a neutral rather than in a protonated form due to considerably higher barriers computed for the protonated adrenaline substrate. The results are discussed in the context of chemical mechanism of MAO enzymes and possible applications of multiscale simulation to rationalize the effects of MAO activity on adrenaline level.