A patient admitted with heart failure who has atrial fibrillation with a rate of 88 bpm while at rest.

A patient with a newly implanted demand ventricular pacemaker, who has sinus rhythm, rate 90 to 100 bpm.

A patient who has just arrived on the unit with an acute MI and has sinus rhythm, rate 76 bpm, with frequent premature ventricular contractions.

A patient who recently started taking atenolol (Tenormin) and has a first-degree heart block, rate 58 bpm.