Abstract: Systems and methods sense stability of an ablation instrument inside a body region. The systems and methods position a tracking element in a fixed location spaced from the ablation instrument. The systems and methods generate an output, which varies according to movement of the ablation instrument relative to the tracking element over time.

Abstract: Heart tissue is characterized by using pacing without inducing ventricular tachycardia (VT). With the tissue characterization, a patient's risk of developing VT can be determined and a slow conduction zone in the patient's heart can be determined. The characterization involves applying pacing signals with varying pacing cycle intervals to a chamber of the patient's heart to pace the patient's heart. The response signals generated by the paced heart are received and used as the basis for characterizing the patient's heart tissue.

Abstract: A medical procedure for treatment of tachycardia (rapid heartbeat) or cardiac disrhythmia uses a catheter which includes a flexible coaxial transmission line (coax) terminated by an antenna. The antenna and coax are introduced into a chamber of the heart. The antenna is brought into contact with a wall of the heart. Action potentials generated by the heart are coupled through the antenna and the coaxial cable to a standard electrocardiograph apparatus for display. Other electrodes placed about the body also produce action potentials which are displayed by the electrocardiograph. The position of the antenna in the chamber of the heart is adjusted with the aid of the displayed action potentials until the antenna is in contact with the region to be ablated or injured as indicated by its characteristic electrical signature.