Surgery: kinesitherapy – Kinesitherapy – Exercising appliance
Reexamination Certificate
1999-06-25
2002-06-18
Yu, Justine R. (Department: 3764)
Surgery: kinesitherapy
Kinesitherapy
Exercising appliance
C601S153000
Reexamination Certificate
active
06406444
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to medical devices and methods. More particularly, the present invention relates to devices and methods for performing minimally invasive direct cardiac massage.
Sudden cardiac arrest is a leading cause of death in most industrial societies. While in many cases it is theoretically possible to re-establish cardiac function, irreversible damage to vital organs, particularly the brain and the heart itself, will usually occur prior to restoration of normal cardiac activity.
A number of techniques have been developed to provide artificial circulation of blood to oxygenate the heart and brain during the period between cardiac arrest and restoration of normal cardiac activity. Prior to the 1960's, open chest cardiac massage (OCM) was a standard treatment for sudden cardiac arrest. Open chest cardiac massage, as its name implies, involved opening a patient's chest and manually squeezing the heart to pump blood to the body. In the 1960's, closed chest cardiac massage (CCM) where the heart is externally compressed through the chest wall became the standard of treatment. When CCM is combined with airway support, it is known as cardiopulmonary resuscitation (CPR). CPR has the advantage that it is much less invasive than OCM and can be performed by less skilled individuals. It has the disadvantage, however, that it is not generally effective. In particular, the medical literature shows that CCM provides significantly less cardiac output, neuroperfusion, and cardiac perfusion than achieved with OCM.
Methods and devices for performing minimally invasive direct cardiac massage have been described by Buckman et al. and by Drs. Filiberto and Giorgio Zadini in the patent and literature publications listed in the Description of the Background Art below. While the methods of Buckman et al. and the Zadinis differ in a number of respects, they generally rely on introducing a balloon, shoe, or other deployable member to engage the heart through a small incision through an intercostal space above the pericardium. The heart may then be pumped by directly engaging and compressing the pericardium, either by inflating and deflating the member or by reciprocating a shaft attached to the member. Although these approaches have been shown to be effective in animal models, the particular devices described in the patents are awkward for emergency use on human patients. In particular, the balloon-type and shoe-type heart-engaging members described in the patents may be difficult to deploy in the potential space between the posterior surface of the rib cage and the pericardium. For example, inflatable balloon members may lack sufficient rigidity to impart the necessary compressive force, rigid shoe-like members risk damage to the pericardium, and cup-shaped compressive members may compress so much of the heart volume that the end diastolic volume is compromised.
For these reasons, it would be desirable to provide improved methods and devices for performing minimally invasive direct cardiac massage. In particular, it would be desirable to provide apparatus and methods which are simple to deploy and carry out and in particular which do not require intervention by a physician. The heart-engaging component(s) of the devices should reliably deploy and expand within the region between the posterior rib cage and the pericardium and should minimize risk to the pericardium from perforation and other damage. The devices and methods should be simple to introduce to the patient in the first place, and in at least some circumstances, should eliminate the need to separately make an incision before introducing the device. The apparatus and method further should be compatible both with manual actuation, i.e., manual reciprocation of a handle or shaft attached to the heart-engaging member, and with automatic or powered systems for reciprocating the member. At least some of these objectives will be met by the invention described hereinafter.
2. Description of the Background Art
U.S. Pat. Nos. 5,582,580; 5,571,074 and 5,484,391 to Buckman, Jr. et al. and 5,683,364 and 5,466,221 to Zadini et al., licensed to the assignee of the present application, describe devices and methods for minimally invasive direct cardiac massage through an intercostal space. Published PCT application WO 98/05289 and U.S. Pat. No. 5,385,528 describe an inflatable device for performing direct cardiac massage. U.S. Pat. No. 3,496,932 describes a sharpened stylet for introducing a cardiac massage device to a space between the sternum and the heart. Cardiac assist devices employing inflatable cuffs and other mechanisms are described in U.S. Pat. Nos. 5,256,132; 5,169,381; 4,731,076; 4,690,134; 4,536,893; 4,192,293; 4,048,990; 3,613,672; 3,455,298; and 2,826,193. Dissectors employing inflatable components are described in U.S. Pat. Nos. 5,730,756; 5,730,748; 5,716,325; 5,707,390; 5,702,417; 5,702,416; 5,694,951; 5,690,668; 5,685,826; 5,667,520; 5,667,479; 5,653,726; 5,624,381; 5,618,287; 5,607,443; 5,601,590; 5,601,589; 5,601,581; 5,593,418; 5,573,517; 5,540,711; 5,514,153; and 5,496,345. Use of a direct cardiac massage device of the type shown in the Buckman, Jr. et al. patents is described in Buckman et al. (1997)
Resuscitation
34:247-253 and (1995)
Resuscitation
29:237-248.
SUMMARY OF THE INVENTION
The present invention provides improved devices and methods for performing cardiac massage, particularly minimally invasive direct cardiac massage where the heart is directly compressed through a small incision formed through an intercostal space over the pericardium. Devices according to the present invention comprise a support and a heart-engaging member attached to the support. The support may be any assembly, structure, system, or other mechanical framework which is suitable for positioning and manipulating the heart-engaging member so that it can engage and compress the heart. Most simply, the support could be a simple handle or shaft having the heart-engaging member attached at a distal end thereof. Once the heart-engaging member is deployed, cardiac massage can be performed by simple manual pumping or reciprocation of the handle or shaft. In the exemplary embodiment described hereinafter, the support comprises a shaft together with a sheath which is coaxially received over the shaft. The shaft and sheath may be manipulated relative to each other to deploy and retract the heart-engaging member, as described in more detail hereinbelow. A wide variety of other supports will also be possible, including supports which comprise powered drivers, such as electric, pneumatic, or other motors. Such drivers can be provided as part of the support, where the driver may be disposed externally, internally, or both externally and internally relative to the patient when the heart-engaging member is deployed over the pericardium.
The heart-engaging member of the present invention comprises a plurality of struts which are reciprocatably attached to the support. The struts are retractable to a radially contracted configuration and advancable along arcuate, diverging paths to define a surface which non-traumatically engages the pericardium to compress the heart when advanced against the pericardium: The struts will typically be composed of a resilient material, more typically be composed of a shape memory alloy, such as nickel titanium alloy, and will usually be formed to deploy radially outwardly and advance along the desired arcuate, diverging paths as they are advanced from a constraining member, usually a tubular sheath. The struts may be advanced and retracted relative to the sheath using any suitable mechanical system, typically a shaft which reciprocates together with the struts through a lumen of the sheath. In some instances, it will be desirable to provide at least some of the struts with a temperature-responsive memory so that the shape of the struts will change in response to a transition from room temperature to body temperature and/or in response to an
Brenneman Rodney A.
Lenker Jay A.
Theracardia, Inc.
Townsend and Townsend / and Crew LLP
Yu Justine R.
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