An interventional medical system comprising: an implantable medical device comprising an electronic controller, a hermetically sealed housing containing the controller, a fixation member, and an extension coupled to the controller, the extension extending from a proximal end of the housing, and the extension including a sense electrode; a delivery tool facilitating deployment of the device, the tool comprising: a handle including a control member; an elongate grasping mechanism including a tubular shaft and a pair of arms longitudinally movable within a lumen of the tubular shaft, each arm including a curved distal end protruding from a distal opening of the lumen of the shaft, at a distal end of the shaft, the curved distal ends being configured to spread apart from one another and to close together, via longitudinal movement of the arms within the lumen of the shaft, characterized by the curved distal ends being configured to grip the extension of the device; and an elongate deployment tube including a proximal end coupled to the control member of the handle, a distal-most portion, and a lumen extending from a proximal opening thereof at the proximal end of the deployment tube to a distal opening thereof that terminates the distal-most portion at a distal end thereof, the grasping mechanism extending within the lumen of the deployment tube such that an entirety of the deployment tube is longitudinally moveable with respect to the grasping mechanism by means of the control member of the handle, and the lumen of the deployment tube, along a length of the distal-most portion, being sized to contain an entirety of the device housing and the fixation member together with the curved distal ends of the arms of the grasping mechanism gripping the device extension when the device extension extends proximally from the distal-most portion within the lumen of the deployment tube; and wherein the grasping mechanism is moveable outside the lumen of the deployment tube, distal to the distal opening thereof. an implantable medical device comprising an electronic controller, a hermetically sealed housing containing the controller, a fixation member, and an extension coupled to the controller, the extension extending from a proximal end of the housing, and the extension including a sense electrode; a delivery tool facilitating deployment of the device, the tool comprising: a handle including a control member; an elongate grasping mechanism including a tubular shaft and a pair of arms longitudinally movable within a lumen of the tubular shaft, each arm including a curved distal end protruding from a distal opening of the lumen of the shaft, at a distal end of the shaft, the curved distal ends being configured to spread apart from one another and to close together, via longitudinal movement of the arms within the lumen of the shaft, characterized by the curved distal ends being configured to grip the extension of the device; and an elongate deployment tube including a proximal end coupled to the control member of the handle, a distal-most portion, and a lumen extending from a proximal opening thereof at the proximal end of the deployment tube to a distal opening thereof that terminates the distal-most portion at a distal end thereof, the grasping mechanism extending within the lumen of the deployment tube such that an entirety of the deployment tube is longitudinally moveable with respect to the grasping mechanism by means of the control member of the handle, and the lumen of the deployment tube, along a length of the distal-most portion, being sized to contain an entirety of the device housing and the fixation member together with the curved distal ends of the arms of the grasping mechanism gripping the device extension when the device extension extends proximally from the distal-most portion within the lumen of the deployment tube; and a handle including a control member; an elongate grasping mechanism including a tubular shaft and a pair of arms longitudinally movable within a lumen of the tubular shaft, each arm including a curved distal end protruding from a distal opening of the lumen of the shaft, at a distal end of the shaft, the curved distal ends being configured to spread apart from one another and to close together, via longitudinal movement of the arms within the lumen of the shaft, characterized by the curved distal ends being configured to grip the extension of the device; and an elongate deployment tube including a proximal end coupled to the control member of the handle, a distal-most portion, and a lumen extending from a proximal opening thereof at the proximal end of the deployment tube to a distal opening thereof that terminates the distal-most portion at a distal end thereof, the grasping mechanism extending within the lumen of the deployment tube such that an entirety of the deployment tube is longitudinally moveable with respect to the grasping mechanism by means of the control member of the handle, and the lumen of the deployment tube, along a length of the distal-most portion, being sized to contain an entirety of the device housing and the fixation member together with the curved distal ends of the arms of the grasping mechanism gripping the device extension when the device extension extends proximally from the distal-most portion within the lumen of the deployment tube; and wherein the grasping mechanism is moveable outside the lumen of the deployment tube, distal to the distal opening thereof.