Apparatus and method for stabilizing the ventricular rate of a heart during atrial fibrillation

A pacemaker implantable in a patient for stimulating the heart, said pacemaker comprising:

• means for generating atrial induced pacing signals for pacing an atrium;
• means for generating ventricular induced pacing signals for pacing a ventricle, in a normal mode of operation, said ventricular induced signals being coupled to said atrial induced pacing signals;
• means for detecting R--R intervals between consecutive R-waves in said heart;
• means for detecting a ventricular rate instability of a ventricular rate by analyzing said R--R intervals;
• means for detecting atrial tachyrhythmia;
• and
• means for increasing said ventricular induced pacing signals gradually when said ventricular rate instability is detected until the ventricular rate is stabilized.

A method of providing pacing signals to a heart with an implanted pacemaker, said method comprising the steps of:

• applying ventricular pacing signals to a ventricle;
• monitoring an atrium to determine atrial instability wherein said atrium exhibits random atrial beats by measuring R--R intervals between consecutive R waves in said ventricle;
• and
• increasing a rate of said ventricular pacing signals gradually until ventricular rate stability is achieved.