Method and apparatus using vagal stimulation for control of ventricular rate during atrial fibrillation

A closed-loop, variable-frequency, vagal-stimulation method for control of ventricular rate during an ongoing atrial arrhythmia, comprising:

• detecting an atrial arrhythmia;
• sensing ventricular excitation rate;
• automatically, upon detection of said atrial arrhythmia, determining a left vagal stimulation frequency and automatically adjusting said vagal stimulation frequency as a function of the difference between actual and desired ventricular excitation rates, said adjusting step including changing said vagal stimulation frequency by a greater amount for one value of said ventricular rate difference than for a smaller value of said ventricular rate difference;
• generating pulses at said vagal stimulation frequency;
• and
• delivering said pulses to a left vagus nerve.

A closed-loop, variable-frequency, vagal-stimulation method of controlling ventricular rate during atrial fibrillation without electrical stimulation of the heart, comprising:

• detecting atrial fibrillation;
• allowing said atrial fibrillation to persist;
• sensing ventricular rate;
• automatically, upon detection of said atrial fibrillation, determining a left vagal stimulation frequency in response to sensed ventricular rate relative to a desired value of ventricular rate, said determining step including increasing said vagal stimulation frequency by an amount directly proportional to a detected difference between sensed and desired ventricular excitation rates;
• stimulating a left vagus nerve at said vagal stimulation frequency during said atrial fibrillation;
• and
• terminating said vagal stimulation frequency upon cessation of said atrial fibrillation.