Surgery – Instruments – Blunt dissectors
Reexamination Certificate
1999-02-03
2001-08-28
Recla, Henry J. (Department: 3731)
Surgery
Instruments
Blunt dissectors
C606S159000
Reexamination Certificate
active
06280455
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to minimally invasive surgical instruments and procedures and, in particular, to surgical tools for dissecting and manipulating an artery, such as the internal mammary artery (IMA), from its natural location in connection with a coronary artery bypass grafting (CABG) procedure. cl BACKGROUND OF THE INVENTION
Surgeons are constantly striving to develop advanced surgical techniques resulting in the need for advanced surgical devices and instruments required to perform such techniques. Recent advances in the surgical field are increasingly related to surgical procedures which are less invasive and reduce the overall trauma to the patient. To illustrate, in a conventional CABG procedure it has been common practice for surgeons to perform a sternotomy to expose the body cavity in the thoracic region. To this end, a surgeon makes a long incision down the middle of a patient's chest, saws through the length of the sternum and spreads the two halves of the sternum apart. Retractors then are employed to provide access to the vessels where an anastomosis will be performed. The CABG procedure is further complicated by the need to stop the beating of the heart by means of cardioplegia and to attach the patient to a cardiopulmonary bypass (CPB) machine to continue the circulation of oxygenated blood to the rest of the body while the graft is sewn in place.
In a procedure known as an “in situ bypass graft,” the surgeon dissects a sufficient length of the artery from its connective tissue, then transects the artery, and connects the transected end to a diseased target coronary artery distal to an obstruction, while leaving the other end of the dissected artery attached to the arterial supply, thus restoring blood perfusion to the heart.
The internal mammary arteries (IMAs), left (LIMA) and right (RIMA), are particularly desirable for use as in situ bypass grafts as they are conveniently located, have diameters and blood flow volumes that are comparable to those of coronary arteries, and in practice typically have superior patency rates. Extending from the subclavian arteries near the neck to the diaphragm and running along the backside of the ribs adjacent the sternum, the IMAs deliver blood to the musculature of the chest wall. The LIMA is typically used as an arterial source for target locations on the left anterior descending coronary artery (LAD), the diagonal coronary artery (Dx), the circumflex artery (Cx), the obtuse marginal artery, and the ramus intermedius coronary artery. The RIMA is typically used for connection to all of the same target locations, as well as the right coronary artery (RCA) and the posterior descending artery.
Use of either IMA as a bypass graft first involves harvesting the IMA free from the inside chest wall. In conventional CABG approaches, access to the IMA is obtained through a sternotomy or major thoracotomy incision (involving sawing through one or more ribs) through the chest. Harvesting of the IMAs is accomplished with relative ease due to the working space made available by the sternotomy or major thoracotomy.
An IMA is detached from its connective tissue until there is sufficient slack in the IMA to allow the distal end thereof to be attached to an incision, generally in the left anterior descending coronary artery (LAD). In preparation for the in situ bypass graft, the sternotomy procedure provides the surgeon with ready access to the IMA since it is exposed by the spreading of the sternum. The IMA thus may be transected at its distal end and detached from the connective tissues in its native location in the sternum region, while still attached at its proximal end to its arterial supply, using the usual surgical instruments such as scalpels, scissors, forceps, etc.
The CABG procedure would be improved if surgeons could avoid the need for arresting the heart, thereby eliminating the need to connect the patient to a cardiopulmonary bypass machine to sustain the patient's life. To this end, recent developments lend themselves to CABG procedures using surgical techniques which enable surgeons to perform the procedure while the heart is beating. This eliminates the need for the lengthy and traumatic cardiopulmonary bypass procedure, cardioplegia is unnecessary, the overall surgery is much less invasive and traumatic, and patient recovery time and costs are reduced.
Recently, progress has been made in advancing minimally invasive surgical techniques, particularly in cardiothoracic surgery, which eliminates the need for a sternotomy or major thoracotomy. Access to the heart with these minimally invasive techniques is obtained through one very small surgical incision (minimal thoracotomy) or through several percutaneous cannulas known as trocar sleeves positioned intercostally in the thoracic cavity of the patient. Visualization of the operative area may be facilitated by thoracoscopes which typically consist of a video camera configured for introduction through a small incision or trocar sleeve to allow observation of the target area on a video monitor.
With the advent of these minimally invasive techniques, harvesting the IMA has become more complex and difficult due to a restricted work space and access, and to reduced visualization of the IMA. The in situ bypass graft procedure and thus the procedure of detaching the IMA likewise must be performed through the minimal thoracotomy. Surgeons presently perform the procedure of detaching the IMA from its native location with the aid of the usual instruments such as the scalpels, scissors and forceps of previous mention. These instruments are not specially designed for use in less invasive procedures and do not facilitate the desired gentle handling of the IMA as it is detached from the surrounding connective tissues to provide the bypass graft for the CABG procedure. The harvesting procedure itself may actually be lengthened and the trauma to the vessel potentially increased by the less invasive techniques, in part because a number of tools must be introduced and exchanged through the restricted incision(s). This is a concern as a high degree of precision is required when harvesting a bypass vessel to avoid injury (such as over cutting or cauterizing) to the vessel which may in turn lead to increased rates of occlusion in the vessel in the months and years after the procedure.
Although low-profile micro-surgical instruments are readily available for some procedures, such has not been the case for harvesting the IMA and other similarly situated arteries in minimally invasive CABG procedures. Surgical instruments designed for laparoscopic and other minimally invasive applications are not generally suitable for performing minimally invasive CABG. Most laparoscopic procedures, for example, target body structures which are quite large in comparison to coronary vessels, and do not require the high degree of precision required in a CABG procedure. Accordingly, laparoscopic instruments generally provide only limited angular orientation, making them unsuitable for harvesting of the IMA and other similarly situated arteries through a minimal thoracotomy or an intercostal puncture site.
Typically an electrosurgical tool (often called a “Bovie”) similar to that described in U.S. Pat. No. 5,013,312 is used to free a length of the IMA by incising the endothoracic fascia and severing the side branch vessels to free the IMA. The use of such electrosurgical devices is well known in the art and can be crucial in controlling bleeding during harvesting of the IMA. Such devices are typically in the form of scalpels, forceps, and scissors, and employ at least one conductive electrode connected thereto.
Despite the use of an electrosurgical tool, because initial cauterization may be applied over too short a length of a vessel or side branch to be complete, it is common practice to apply sutures or surgical clips to control bleeding before complete coagulation is effected. Applying and removal of clips or sutures can be time-consuming. In addition, if clips are accidenta
Ginn Richard S.
Sepetka Ivan
Shennib Hani
Taylor Charles S.
Cardiothoracic Systems, Inc.
Fenwick & West LLP
Recla Henry J.
Truong Kevin
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