Position control of catheters using magnetic fields

We describe a computerized closed-loop control system for navigating catheters, guidewires and other interventional devices inside the human body for minimally invasive diagnostic and therapeutic applications. Each device contains a permanent magnet near its distal tip. An external magnetostatic field, whose direction and magnitude can be selectively varied, is applied to the vicinity of the tissue where the medical procedure is being performed, in order to orient the catheter tip. At the same time, the length of the catheter is varied by a motorized advancer. The position and orientation of the catheter tip is determined in real-time by electromagnetic means. This information is fed into a control algorithm which decides how to change the external magnetic field and the catheter length. In this way, the catheter is automatically navigated to anatomical target points selected by the physician. Although potentially not limited to cardiology, most common applications at present include navigation inside the heart and coronary vessels, electrophysiology and interventional cardiology. Possible future clinical applications include atrial fibrillation, flutter and tachycardia, ventricular tachycardia, angioplasty, etc. The resulting system has more predictable navigation performance compared to manually deflected catheters, and provides an opportunity to shorten the procedure time considerably.