Clinical approach to paroxysmal atrial fibrillation

Abstract

Summary: In addition to the role of the electrophysiological substrate, paroxysmal atrial fibrillation depends on the modulation of the atrial tissues by the autonomic nervous system. Experimentally, models of atrial fibrillation can be based on either adrenergic or vagal stimulations that provoke the arrhythmia by disturbing in a different way conduction and refractory periods of the atrium. Clinically, the role of the autonomic nervous system can be suspected from the clinical history, and paroxysmal attacks can typically be observed either at daytime or at night, at exercise or at rest. Careful attention should be paid to the changes of heart rate that occur in the minutes or tens of minutes prior to the attacks, and the trend of acceleration or slowing of cardiac frequency observed in Holter tracings provides reliable indications of the state of the vago-sympathetic balance in these patients. During the attacks, the electrocardiographic aspect of atrial flutter alternating with a pattern of atrial fibrillation is typical of vagally dependent arrhythmias, whereas atrial tachycardia is more frequently observed at the onset of adrenergic atrial fibrillation. When the paroxysmal forms of arrhythmia are resistant to usual pure antiarrhythmic therapy including type IA agents and flecainide or encainide, one should take into account the role of the autonomic nervous system. Propafenone, or beta-blockers combined with type I drugs, are very effective every time an adrenergic factor is involved, but prevent the benefi- cia1 role of other agents if a vagal mechanism is predominant. Amiodarone, a complex drug with multiple facets, can be active in many different situations but its use should be reserved to definitely resistant cases, in combination with other agents, in order to limit its potential long-term side effects. Digitalis and verapamil mainly address the tolerance to arrhythmias, rather than their prevention.

Altered Complexity and Correlation Properties of R-R Interval Dynamics Before the Spontaneous Onset of Paroxysmal Atrial Fibrillation

“…6 -10 The autonomic nervous system may play an important role as a trigger for the spontaneous onset of paroxysmal atrial fibrillation (AF). 11,12 However, only a few and partly controversial reports exist concerning changes in HR variability preceding the onset of AF. [13][14][15][16] A recent study suggested that altered complexity of R-R interval dynamics precedes the AF episodes of patients after coronary artery bypass graft surgery.…”

RR Interval Dynamics Before Atrial Fibrillation in Patients After Coronary Artery Bypass Graft Surgery

“…8 -10 Autonomic nervous system perturbations may enhance vulnerability to atrial arrhythmias. 5,[11][12][13][14] Analysis of HRV has been used to probe autonomic mechanisms of ventricular tachycardia and fibrillation and to identify patients at risk for ventricular arrhythmias. [15][16][17][18][19][20] Preliminary investigations in primarily nonsurgical populations have suggested that risk for AF may be identified with measurement of HRV, but whether the onset of postoperative AF is preceded by autonomic dysfunction is not clear.…”

“…[15][16][17][18][19][20] Preliminary investigations in primarily nonsurgical populations have suggested that risk for AF may be identified with measurement of HRV, but whether the onset of postoperative AF is preceded by autonomic dysfunction is not clear. 13,14,[21][22][23] Moreover, initial evaluations of HRV and AF risk have been limited to the usual time or frequency domain measures of HRV. 13,14,[21][22][23] Nonlinear methods of HRV analysis provide information about the dynamics of heart rate not evident with traditional methods of HRV measurement.…”

American College of Cardiology, American Heart Association and European Society of Cardiology (2006) Guidelines for the Management of Patients With Atrial Fibrillation

“…У некоторых пациентов без структурных изменений сердца в тече-ние нескольких минут до развития ФП обнаруживали преобладание парасимпатического тонуса, в то время как у других отмечалось смещение баланса в сторону симпатической нервной системы [108,109]. У части па-циентов можно выделить вагальную или адренерги-ческую формы ФП [110]. ФП, опосредованная пара-симпатической активностью, обычно возникает ночью или после еды, в то время как адренергическая ФП в типичном случае развивается в дневное время [111].…”