Technological Innovations

New technologies have played crucial roles in the evolution of less-invasive cardiac surgery. Importantly, they have changed the perceptions of cardiac surgeons regarding how cardiac surgery can or should be performed. With the help of new instruments specifically designed to meet the surgeon's need, less-invasive cardiac surgical procedures once deemed impossible or impractical have now become reality, or even common practice, in some medical centers. These technological innovations have typically involved the aspects of cardiac surgery discussed in this section.

5.1. Sternum-Sparing Surgery,

Minithoracotomy, and Thoracoscopy

Major advances in the area of sternum-sparing surgery, mini-thoracotomy, and thoracoscopy include the development of a cardiopulmonary bypass support system via peripheral access. The application of suction to the venous drainage has made possible aortic valve and mitral valve surgery via partial sternotomy, as well as mitral valve surgery via a minithoracotomy. An earlier breakthrough device in this field was the HeartPort system (Heartport; Redwood City, CA); although its use has proven impractical in most cardiac operations, its potential has significantly changed cardiac surgeons' perception of future technologies. Furthermore, the concept of the HeartPort system led to numerous other technological modifications and innovations in the field of less-invasive cardiac surgery. Such innovations include: (1) transesophageal echocardiography to guide venous cannulation; (2) development of the Chitwood aortic cross-

Coronary Bypass Anastomosis
Fig. 2. An octopus myocardium-stabilizing device was used to steady the coronary artery during direct bypass grafting anastomosis.

clamp; and (3) mitral valve repair or replacement with the assistance of thoracoscopy.

5.2. OPCABG Improvement

New instruments have also been developed to position the heart and to stabilize and improve the visualization of target arteries. For example, an available left ventricle suction device applies -400-mmHg suction to the left ventricular apex and can hold the heart up in different positions. Now widely used in OPCABG surgery, it has less of an effect on the venous return compared with the old "suture retraction" technique. Similarly, a focal myocardial stabilization device has been developed to stabilize segments of target arteries; it has both a suction and a compressing effect on the topical epicardial tissue and thus significantly decreases the motion of target arteries (Fig. 2). An additional noteworthy device is the temporary intracoronary plastic shunt; it can be inserted via arteriotomy to maintain blood flow to the distal myocardium during anastomosis, thus avoiding or minimizing ischemia time. Importantly, the use of such a shunt is considered crucial when the target artery supplies a large territory of myocardium.

5.3. Aortic Nontouch Techniques

Different proximal anastomotic devices are being developed to avoid clamping on the aorta during OPCABG surgery. Two such devices have been approved by the Food and Drug Administration. One is the automated proximal connector from St. Jude Medical (St. Paul, MN), which allows the vein graft to be anastomosed to the aorta without side-clamping and suturing. An early detected drawback of this preliminary model is that the proximal anastomosis must be performed first, making it difficult to assess the length of the vein graft when the distal anastomosis is performed; moreover, a delivery device must be inserted into the lumen of the vein graft, which can denude the endothelium and affect long-term patency. Nevertheless, in time, new innovations will likely correct for these noted compromises. The other device is Heartstring™ Proximal Seal System (Guidant Corporation, Indianapolis, IN), which temporarily occludes aortotomy during direct suture anastomosis of the proximal vein graft to the aortotomy; yet, to date one of the major drawbacks of its use is that the suture can catch the device, which requires that the anastomosis be redone.

5.4. Endoscopic Robotics

Someday soon, will operating rooms be devoid of cardiac surgeons? Perhaps, with the addition of robotics as a forefront technology. For example, Intuitive Surgical's (Sunnyvale, CA) daVinci robotic system has improved significantly and has made operating inside the chest cavity possible. Its 3D visualization, seven degrees of wrist motion, and capability to eliminate human hand tremors facilitate fine cutting and suturing tasks. For those few surgeons who are currently using these sophisticated machines, it has made internal mammary artery takedown and OPCABG surgery via minithoracotomy easier (Fig. 3). Further, it has been described to have been used to repair atrial septal defects and mitral valves without sterno-tomy or thoracotomy. Currently, the employment of such systems will lead the way in moving toward total endoscopic CABG surgery (Figs. 4 and 5).

Nevertheless, numerous complementary innovations have been required to allow for robotic surgery on the heart. For example, to make OPCABG surgery easier when it is performed via minithoracotomy or total endoscopic robotic approaches, an "endo suction device" and an "endo myocardium stabilizer"

Left Internal Mammary Vein
Fig. 3. Robotic arms operate inside the chest cavity to take down left internal mammary artery.
Peripheral Anastomosis Device Cabg

have been developed to position the heart and stabilize the target artery through port accesses. Other devices that are currently being developed include proximal and distal anastomotic devices and endo "U" clips.

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