The traditional implantable cardiac pacemaker includes a pulse generator device to which one or more flexible elongate lead wires are coupled. The device is typically implanted in a subcutaneous pocket, remote from the heart, and each of the one or more lead wires extends therefrom to a corresponding electrode, coupled thereto and positioned at a pacing site, either endocardial or epicardial. Mechanical complications and/or MRI compatibility issues, which are sometimes associated with elongate lead wires and well known to those skilled in the art, have motivated the development of implantable cardiac pacing devices that are wholly contained within a relatively compact package for implant in close proximity to the pacing site, for example, within the right ventricle RV of the heart. With reference to FIG. 1, such an implantable medical device 100 is illustrated, wherein an hermetically sealed housing 105, preferably formed from a biocompatible and biostable metal such as titanium, contains a pulse generator, or an electronic controller (not shown), to which at least one electrode 111 is coupled, for example, by a hermetic feedthrough assembly (not shown) like those known to those skilled in the art of implantable medical devices. Housing 105 may be overlaid with an insulative layer, for example, medical grade polyurethane, silicone, or parylene.
FIG. 1 further illustrates a distal portion of a standard guiding catheter 150 having been maneuvered up through the inferior vena cava IVC and into the right ventricle RV from the right atrium RA, according to methods known in the art of interventional cardiology. Although catheter 150 may be employed to deliver device 100 to the right ventricle RV, for implant, more sophisticated tools, which are more suitable to facilitate deployment of relatively compact implantable devices, like device 100, are desired.