In a system for retrieving an implanted device, a flared inner surface of a catheter tubular sidewall may define a distal-most opening of a device receptacle; the opening has a first diameter equal to that of the receptacle, and a second diameter, coincident with a distal-most edge of the tubular sidewall, and at least 5% greater than the receptacle diameter. Alternately, a retrieval tool in sliding engagement within a lumen of a catheter includes a shaft assembly, through which a snare member passes, and which includes a collapsible spring-biased perimeter sidewall; the sidewall defines a capture member passageway approximately coaxial, and in fluid communication with a lumen of the shaft assembly. A distal-most opening of the passageway has a spring-biased diameter that is greater than that of a distal-most opening of a device receptacle of the catheter, and a collapsed diameter that is less than the receptacle distal-most opening diameter.