Pericardium retraction device for positioning a beating heart

Surgery – Instruments – Forceps

Reexamination Certificate

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C600S206000

Reexamination Certificate

active

06517563

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to the field of surgical apparatus and more specifically, to a tissue retraction device for positioning and orienting a beating heart during cardiac surgery.
BACKGROUND OF THE INVENTION
Coronary artery bypass graft (CABG) surgery is a widely practised surgical procedure for performing coronary artery revascularization or bypass grafts. This surgical procedure consists of replenishing or augmenting blood flow to a portion of the patient's heart which is being deprived of such flow due to a restriction or blockage in a coronary artery supplying the said portion of the patient's heart. A healthy segment from a blood vessel, such as an artery or a vein converted into an artery, is attached to the patient's vasculature from a point upstream of the coronary artery restriction or blockage to a point downstream thereof, thereby creating the bypass artery and associated bypass blood flow. Since the great majority of CABG surgeries are multi-vessel bypasses, this surgical procedure remains one of the most common and effective treatments for coronary artery disease.
Traditional CABG surgery has been commonly performed through a midline sternotomy incision, where the patient's sternum is incised and the ribcage retracted to obtain access mainly to the patient's heart, the coronary vessels, and other internal thoracic arteries. Intercostal thoracotomy approaches have also been employed whereby two adjacent ribs are spread apart, at times even removing a length of rib to improve access into the patient's thorax. In both approaches, a surgical retractor is used to spread the patient's skin and bone structure and to maintain an incised opening or surgical window onto the underlying heart and coronary vessels.
CABG surgery has been traditionally performed with the support of a cardio-pulmonary machine, whereby the patient's blood is oxygenated outside the body through extracorporeal circulation (ECC). This allows the surgeon to perform surgical procedures on a near perfectly still heart while the patient's life support is maintained by cardiopulmonary assistance. During traditional CABG surgery, the surgeon or assistant may manually or otherwise manipulate the arrested heart into a position and orientation that yields the best access to the target artery requiring the bypass graft. The great majority of CABG surgeries (approximately 70%) are triple vessel bypass surgeries; that is, at least one bypass graft is performed on each of the anterior, inferior and posterior artery beds of the patient's heart.
Recently, in an aim to render CABG surgery less invasive to the patient, beating heart CABG surgery is being developed whereby ECC, one of the most invasive aspects of cardiac surgery, is eliminated and coronary artery revascularization is performed directly on the beating heart. One of the challenges in performing beating heart CABG surgery lies in positioning and orienting the beating heart in order to obtain access to the inferior and posterior artery beds, while aiming to minimize physiologically undesirable effects such as hemodynamic instability, arrhythmia, or a precipitous drop in arterial pressure, any of which may occur as a result of such beating heart manipulation. Furthermore, a surgical device which enables manipulation of the beating heart or which restrains its movement or positioning may impose loads and constraints on the beating heart. This may impede the normal beating function of the heart and induce the onset of the physiologically undesirable effects described above. In traditional CABG surgery, the heart is arrested and therefore heart manipulations are well tolerated.
During CABG surgery or beating heart CABG surgery, the pericardium, namely the substantially thin membranous tissue forming a sac in which the heart and the commencement of the major blood vessels connecting with the heart are contained, is generally incised and unraveled to expose at least a portion of the heart surface which is to receive the bypass graft. The pericardium tissue, unlike the heart, is not beating and it may be separated from the heart surface except in certain locations where it is anatomically attached to the heart. Thus, it is surgically possible in CABG surgery to position and orient the heart through retraction, positioning and loading of the pericardium tissue to obtain access to the inferior and posterior coronary artery beds. In beating heart CABG, heart manipulations achieved through retraction of the pericardium tissue tends to reduce the likelihood of inducing trauma to the beating heart and tends to minimize the physiologically undesirable effects mentioned above, since direct contact with the beating heart is avoided. One such beating heart manipulation consists of “verticalizing” the heart in order to gain access to the posterior artery bed. In this maneuver, the pericardium is engaged close to the base of the heart, preferably 1.5 inches from pericardial reflection, and the apex of the heart is rotated outward from retracted chest cavity through the tensile loads applied to the engaged pericardium. The longitudinal axis of the beating heart thereby assumes a substantially vertical orientation.
The desired position and orientation of a beating heart may be maintained, at least in part, by maintaining retraction loads applied to the pericardium tissue and securing the surgical apparatus that applies the tensile load to pericardium tissue. During CABG surgery, a deployed surgical retractor provides a suitable stable platform for the securement of the pericardium retraction loads. The pericardium tissue may be engaged by a variety of methods. Sutures such as traction or stay sutures have been generally employed in cardiac surgery to retract tissue during a surgical intervention. Traditionally sutures consist of tissue piercing member such as a relatively sharp needle and a length of wire-like filament such as a suture line integrally attached to the blunt end of said needle. Pericardium retraction may be achieved through the application of pericardial traction sutures whereby the needle pierces the pericardium tissue, threading a certain length of suture line through the pierced pericardium tissue, and pulling simultaneously on both the resulting lengths of suture line; that is, the length between the pierced tissue and the free end of the suture line, and the length between the pierced tissue and the needle-bearing end of the suture line, to displace the pericardium tissue and consequently the beating heart anatomically attached to the pericardium.
In order to “verticalize” a beating with pericardial traction sutures, a number of such sutures must be inserted through and engaged with the pericardium tissue preferably along its pericardial reflection in order to get the desired lifting of the heart apex and consequently the best exposure to the posterior coronary bed. For example, one traction suture may be placed between the superior and inferior pulmonary vein, a second one below the inferior pulmonary vein, a third one midway between the apex of the heart and the inferior pulmonary vein, and a fourth one towards the diaphragmatic face near the inferior vena cava. Pericardium retraction loads are subsequently applied to each of these traction sutures independently. The resulting lengths of suture line must then be secured to a stable surgical platform such as the sternum retractor to maintain the desired retraction load on the pericardium tissue.
During the placement of these pericardial traction sutures deep within the patient's thorax and close to the base of the beating heart, the surgeon's view of the body tissue contained beyond the unraveled pericardium tissue is hindered. Consequently, because of this blind installation, the risk of unintentionally puncturing other underlying body tissue with the tissue piercing needle may lead to operative or postoperative complications, especially when a number of such sutures is required. For instance, an inadvertent punct

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