A body comprising a nut retaining apparatus mounted thereon for fastening a bolt to the body. The electronic sensor can be positioned at various heights relative to the fill tube to provide variability in the height of the fill line. The high and low-side drive signals include a plurality of dead-time periods. This system and method can greatly simplify the image processing required to analyze the 3D model by moving the analysis techniques back into the 2D domain. In certain exemplary embodiments, the methods and devices are particularly useful during open or translumenal surgical approaches to apply long-term retrograde perfusion of the myocardium, the neurosystem, or a periphery, such as the arm or leg, thereby treating various medical conditions, such as coronary artery disease, stroke, renal failure, etc.