Congestive heart failure (“CHF”) is characterized by the failure of the heart to pump blood at sufficient flow rates to meet the metabolic demand of tissues, especially the demand for oxygen. It has been determined that a passive wrap, or cardiac harness, may increase the efficiency of a heart affected by congestive heart disease. While advances have been made in cardiac harness technology, a satisfactory device for delivering and positioning the cardiac harness onto a patient's heart has yet to be provided.
In one method, access to a patient's heart is achieved through an open chest procedure, wherein the sternum is split and separated to allow access to the heart. The cardiac harness is then positioned over the heart by manual manipulation. Such an open chest procedure is highly traumatic to the patient and, thus, remains a relatively undesirable option for cardiac harness delivery.
Present cardiac harness delivery devices are adapted for use in minimally invasive procedures in which the delivery devices are advanced through a relatively small incision through the body cavity of a patient. Because of the relatively rigid structure and size of such delivery devices, separate introducer devices are used to create an entry path sufficient in size to allow the delivery device to access the heart. In addition, access to the apex of the heart is typically required, in which case an entry path that passes between two ribs is convenient. Importantly, since CHF hearts are enlarged, they have an apex that is rounded which presents a very steep angle of approach when mounting a cardiac harness over the heart.
An example of an introducer assembly 160 usable to assist in creating an access opening in the pericardium of a patient's heart to permit deployment of a medical device, such as a cardiac harness, to the heart is provided in FIGS. 26, 27, and 28. In this embodiment, the introducer assembly includes an introducer sleeve 162 and a dilator sleeve 164. The introducer sleeve 162 has outwardly extending flanges 150 at the proximal end 152, the flanges being sufficiently sized to serve as a grip. With the flanges, the introducer sleeve may be easily held in place by the doctor while inserting the dilator sleeve 164.
With particular reference to FIG. 26, the introducer sleeve 162 is a thin-walled, tubular element having a substantially circular cross-sectional shape. A distal end 163 of the introducer sleeve 162 comprises a plurality of flared portions 165 that are biased outwardly from a longitudinal axis As of the introducer sleeve 162. In the illustrated embodiment, a portion of the introducer sleeve 162 is divided into several elongate strips 166 that are spaced apart from each other. A resilient annular member, such as an elastic ring 168, is positioned toward the distal end 163 of the introducer sleeve 162 to bias the strips 166 into a reduced-diameter configuration, which is operable to ease insertion of the introducer sleeve 162 into an incision in the pericardium.
Referring now to FIG. 27, the dilator sleeve 164 is a thin-walled, tubular member, which is also substantially circular in cross-section. The dilator sleeve 164 is slidably inserted within the introducer sleeve 162, as illustrated in FIG. 28 to expand the strips 166 and flared portions 165. In particular, the dilator sleeve 164 presses against an inner surface of the reduced-diameter portion of the introducer sleeve 162 to force the reduced-diameter portion outward against the biasing force provided by the elastic ring 168. Thus, in the assembled configuration, the reduced diameter portion of the introducer sleeve 162 is enlarged and the introducer assembly 160 is configured to provide an access pathway for the delivery device 30. The dilator sleeve 164 also has an enlarged diameter portion 170 on its proximal most end to limit the insertion within the introducer sleeve 162.
FIG. 29 illustrates a human heart 172, which is enclosed within a pericardium 174. To permit introduction of the delivery device 30 to a location within the pericardium 174, preferably, a small incision 176 is made in the pericardium 174 adjacent the apex of the heart. With reference next to FIG. 30, the introducer sleeve 162, in its contracted, or collapsed, orientation is introduced into and through the incision 176. In practice, one side of the distal end of the introducer sleeve 162 may be inserted into the incision 176 first, followed by the remaining side.
With reference next to FIG. 31, once the flared portions 165 of the introducer sleeve 162 have been advanced through the slit 176, the dilator sleeve 164 is then introduced within the introducer sleeve 162 to urge the introducer sleeve 162 into its expanded configuration. In this configuration, the flared portions 165 are expanded to a diameter greater than the diameter of the rest of the introducer sleeve 162 and preferably greater than the size of the incision 176. As such, the flared portions 165 press upon and open the incision 176 and the surrounding portion of the pericardium so as to create a space between at least part of the pericardium and the heart. Further, the flared portions 165 function as a lock to resist pulling the introducer out of the incision 176. Accordingly, the introducer assembly 160 is effectively locked in place between the heart 172 and the pericardium 174.
Since the dilator sleeve 164 dilates the introducer sleeve 162, an access pathway is created to allow the delivery device 30 to be advanced through the dilator sleeve, the introducer sleeve, and through the pericardium to deliver the cardiac harness 42 onto the heart 172. When the procedure is completed, the delivery device 30 is retracted through the access pathway and the introducer arrangement 160 is removed in generally the reverse order of the insertion.
While the above discussed and illustrated introducer assembly has provided a significant advance in the art and has provided advantages in delivering cardiac harnesses recognized and appreciated by many in the art, it has also been recognized that providing even smaller delivery devices that may accomplish both the introducing and delivery functions simultaneously would be desirable. Provided that such smaller delivery devices are in fact less traumatic, include fewer parts or complexity, and provide equivalent functionality, such would be of interest.