With pressures on the health care system to continually reduce treatment costs and document the outcome benefits of a given therapy, much effort will continue to be placed on procedural improvements for cardiac care.
The ability to image internal and external features of the heart continues to improve at a rapid rate and, as indicated in Chapters 18 and 19 on echocardiography and magnetic resonance imaging, respectively, the sophistication of such systems can be quite extreme. Yet, as the cost of computer hardware continues to decrease while capabilities increase, opportunities to develop such technologies for widespread use become feasible.
Intracardiac echocardiography (ICE) has many possible applications, including guidance of radiofrequency ablation procedures and visualization of cardiac anatomy and physiology. Compared to standard 2D imaging, emerging 3D echocar-diography may provide additional clinical utility. To assess this, our laboratory compared real-time 3D ICE (RT3D ICE) images to capture real-time video images simultaneously in an isolated four-chamber working swine heart (19). The comparative images obtained in this study verified the ability of RT3D ICE to provide appropriate anatomical identification that could be applied to clinical practice. Stationary anatomical structures (i.e., coronary sinus ostium) are easily visualized with static 3D ICE images (Fig. 8). Moving structures (i.e., valves) were not easily distinguished on RT3D ICE when presented as still images; however, they were more easily identified during acquisition and full-speed playback.
Cardiovascular device companies typically work closely with clinicians to develop not only new technologies, but also modifications of existing devices or enhanced means to deploy them with better precision. One example of such a collaboration is the recently marketed implant tool for the placement of epi-cardial leads during a less-invasive surgery. This malleable epicardial lead implant tool features a stainless steel shaft that can be shaped to maneuver and position a lead optimally on the posterior of the heart, either on the right or the left ventricle (Fig. 9).
Another example of an innovative device that has been developed to fit a unique need is the device designed to trap plaque that may dislodge during interventional procedures; such plaque might otherwise migrate to smaller vessels, causing serious endovascular deficits. The SPIDER™ Embolic Protection Device (ev3 Inc., Plymouth, MN) is specially designed for capture and removal of dislodged embolic debris before it can harm the patient (Fig. 10). This device is considered to provide protection while conforming to the requirements of the primary intervention. The SPIDER™ Embolic Protection Device has been recommended to provide distal embolization protection in patients during a general vascular procedure, including peripheral, coronary, and carotid interventions.
In Chapter 28, the rapidly advancing field of less-invasive cardiac surgery and some initial uses of robotics to perform epicardial procedures (e.g., bypass grafting and lead implantations) were described. such approaches are becoming more practical because better tools to perform such procedures are continually refined. For example, the Octopus®3 Tissue Stabilizer (Medtronic, Inc.) is the pioneering and market-leading suction device featuring (1) malleable stabilizer pods that can be formed to the unique contours of the patient's anatomy and (2) a unique tissue-spreading mechanism that enhances stabilization of the anastomotic site and presentation of the coronary (Fig. 11). Similarly, the Starfish™ Heart Positioner (Medtronic, Inc.) has been shown to simplify cardiac positioning and thus minimize associated hemodynamic deterioration (20).
As cardiovascular surgeries employ less-invasive techniques, more and more novel devices and tools will be needed. For example, the HEARTSTRING™ Proximal Seal System (Guidant, Indianapolis, IN) is a unique means to perform bypass procedures that meet the challenge of clampless hemostasis; another example is the Symmetry Bypass System (St. Jude Medical, St. Paul, MN). Both of these devices allow the surgeon to complete coronary artery bypass successfully without cross-clamping or side biting (Fig. 12).
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.