Surgery – Miscellaneous – Methods
Reexamination Certificate
2000-01-21
2002-11-12
McDermott, Corrine (Department: 3738)
Surgery
Miscellaneous
Methods
C600S221000
Reexamination Certificate
active
06478028
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a surgical apparatus and method for performing less-invasive surgical procedures, and more specifically, to a surgical apparatus and method for performing a surgical procedure on the beating heart, such as stabilizing a portion of a beating heart during a coronary artery revascularization, wherein said surgical procedure is performed through a percutaneous transabdominal approach.
BACKGROUND OF THE INVENTION
Cardiac surgery, and more specifically traditional coronary artery bypass graft (CABG) surgery, has been performed since the 1970's on a regular basis with the advent of the cardio-pulmonary machine. In traditional CABG, the patient's heart is exposed by cutting through the patient's sternum and retracting the two halves of the ribcage. The heart is subsequently stopped while the blood continues to be pumped and oxygenated outside the body through extracorporeal circulation (ECC). The development of the cardio-pulmonary machine for ECC enables surgical interventions to take place on an arrested heart. This allows the surgeon to manipulate and operate on a perfectly still heart. As such, the arrested heart may be positioned to expose and provide the best access to the target artery requiring a bypass grafting.
However, there are two main invasive aspects associated to traditional CABG—the sternotomy incision and the ECC. Even with the constant technological improvements achieved during the last twenty-five years, the advantages offered with ECC have been at times offset by the morbidity (complications) and mortality related to the ECC itself. ECC has been documented to produce some well-known complications. Adverse effects associated with its use continue to be discovered and as such, ECC represents one of the most invasive clinical aspect associated with traditional CABG surgery. The inflammatory response, as well as the systemic microembolisms generated by ECC, induce to some extent a dysfunctional state of the brain, lungs, and kidneys, which tends to increase with the aging of the patient. Furthermore, evidence suggests that when ECC can be avoided, the left ventricular function (pumping efficiency) of the heart is better preserved, thereby also reducing the risks of post-operative complications and the need for ventricular assist devices to wean the arrested heart back to normal function. In addition to being one of the most invasive aspects of traditional CABG, ECC is also responsible for a large percentage of the initial procedure cost of traditional CABG. If ECC-related complications develop, ECC is also responsible for the post-operative costs incurred to treat these complications.
A median sternotomy, although less clinically-invasive than ECC, has the perception of being more invasive due to the surgical scaring that results from the surgery. A full median sternotomy may result in a temporary disturbance in the respiratory mechanism, an increased risk of operative shock or dehiscence, and re-operation surgery from bleeding complications. Moreover, prolonged exposure to air of the exposed mediastinum may lead to hypothermia, infection or compromise of the neuro-endocrine response. Patients with severe chronic obstructive pulmonary disease (COPD), severe emphysema or severe pulmonary insufficiency are therefore at a higher risk of developing complications when exposed to a sternotomy incision.
Port access surgery, developed largely by Heartport Inc. of Redwood City, Calif., consists of replacing the full median sternotomy by a series of intercostal port incision in the patient's chest, through which coronary artery revascularization is performed. However, the most invasive aspect, ECC, is retained in this type of surgery. The patient's heart is arrested by occluding the patient's aorta preferably between the coronary arteries and the brachiocephalic artery with an expandable balloon on the distal end of an endovascular catheter which may be introduced via a femoral artery. Cardioplegic fluid is then delivered to the patient's myocardium through a lumen in the same catheter or through a separate catheter positioned in the coronary sinus. A series of cannulae and catheters are usually employed to divert the patient's blood flow to the cardio-pulmonary machine and to return the oxygenated blood to the circulatory system while the aorta remains occluded to avoid backflow into the heart chambers and surgical field. The port access approach most often also requires lung deflation in order to improve the access to remote territories of the heart, such as the posterior coronary territory. Unlike traditional CABG, the longitudinal axis and apex of the heart cannot be “verticalized” with respect to the surgical table and retracted chest cavity tending to facilitate access to the posterior territory. Performing port access surgery remotely through a number of small ports tends to be difficult, at times leading to unwanted tissue dissection that requires the conversion to a full sternotomy in order to complete the surgical procedure.
In recent years, the drive for less-invasive and cost-effective surgical approaches and apparatus has placed emphasis on cardiac surgery as well. However, unlike other organ surgeries, gall bladder for instance, the beating motion of the heart tends to complicate the surgical intervention.
In minimally invasive direct coronary artery bypass graft surgery (MIDCAB), ECC is avoided and coronary artery revascularization is performed directly on the beating heart with the help of a mechanical coronary artery stabilizer, through a mini-sternotomy or mini-thoracotomy incision. This surgical approach allows access to only one or two of the anterior arteries of the heart, most commonly the left anterior descending artery (LAD). Demographically, only 5-15% of the cardiac surgery population is afflicted with single vessel disease; the majority of cardiac patients (70%) suffer from triple vessel disease, whereby at least one artery on each of the anterior, inferior and posterior territories of the heart requires a bypass graft. As a result, this approach has also been referred to as “limited access bypass surgery”. Moreover, the MIDCAB thoracotomy incision to access the beating heart has been discovered to be more painful and less tolerated by patients than originally anticipated, especially in younger patients.
More recently, the beating heart approach through a sternotomy incision has been adopted tending to facilitate positioning of the beating heart within the retracted chest cavity and tending to facilitate grafting of the difficult to access posterior arteries. Mechanical coronary artery stabilizers have been developed to immobilize a portion of the beating heart surface proximate to the target artery during the distal anastomosis phase of the surgery. A median sternotomy is desirable since it tends to allow the apex of the beating heart to clear the retracted ribcage as the heart's longitudinal axis is “verticalized” in order to expose the posterior coronary territory. In some patients, verticalization of a beating heart is not well tolerated and may lead to hemodynamic instability during the surgical procedure. At times, this unnatural “verticalized” orientation of the beating heart may be attained with some degree of atrial or ventricular distortion, and even some degree of valvular dysfunction and regurgitation. Moreover, although the beating heart approach achieves the elimination of the cardio-pulmonary machine, the sternotomy incision with its associated complications is retained in this approach.
Percutaneous transluminal angioplasty (PCTA) or Coronary Stenting are intraluminal surgical procedures which achieve coronary artery revascularization through the enlarging of restricted vessels by balloon angioplasty (PTCA) and in some cases also supplemented by the scaffolding effect of the tubular mesh stent. Sternotomy incisions and ECC are avoided since the entire procedure takes place through the patient's artery. However, the high
Cartier Raymond
Paolitto Anthony
Valentini Valerio
Barrett Thomas
Coroneo Inc.
McDermott Corrine
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