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Cardiac pacemakers: current concepts.

Cardiac pacemakers are generally used in conditions where bradyarrhythmia is a major problem, such as advanced heart block, sick sinus syndrome and bundle branch block. Temporary or permanent pacing may be needed to control certain tachyarrhythmias refractory to medical therapy. Temporary pacing may be of value in the diagnosis of sinus node dysfunction and preexcitation syndrome, and may be used expectantly in some patients with acute myocardial infarction.