|
In patients with chronic atrial fibrillation (AF), control of ventricular rate
both at rest and during exercise are necessary as a rapid heart rate may produce variety of clinical symptoms,
limit exercise capacity and affect cardiac function. Determinants of ventricular rate in chronic AF are
multifactorial and include the atrial rate, properties of the atrioventricular (AV) node, structural integrity of the
AV conduction system, underlying heart disease, age and the state of autonomic nervous system.
The information on the optimal ventricular rate control in chronic AF is limited. Recently, the new criteria for
ventricular rate control in chronic AF were suggested. In rest, the ventricular rate should be ranging from 60 to
80 beats/min, during daily activities from 90 to 115 beats/min, and during submaximal or maximal exercise from
110 to 150 beats/min (individual approach).
Control of heart rate in chronic AF may be achieved with drugs or with radiofrequency AV node ablation or
modification. Among various drugs, digitalis is treatment of choice for patients with heart failure and/or left
ventricular systolic dysfunction, and for older patients with limited physical activities. The calcium channel
blockers and beta-blockers should be preferred in other clinical settings, because they better control ventricular
rate during exercise. The choice between these two classes of drugs depends on the associated clinical and
medical conditions. The AV node ablation should be reserved for symptomatic patients with chronic AF in whom
pharmacological inventions for rate control were ineffective, while the AV node modification is not yet
recommended for routine clinical use.
|
