referring firstly to fig1 and 2 there is shown a first embodiment of an intravascular heart assist device 10 according to the invention . the device 10 includes an inelastic , preferably plastic , shell 12 and a membrane 14 , sealingly attached to periphery of the shell 12 . the membrane 14 defines an inflatable space 16 between it and the interior of the shell 12 . the shell 12 also has an inlet / outlet port 18 which is adapted for connection to a motive means ( not shown ) that can periodically introduce , and withdraw , a fluid ( eg ., a gas such as helium or a liquid such as a saline solution or an oil ) to and from the space 16 ( to expand and retract the membrane 14 respectively ) in counter - pulsation with the patient &# 39 ; s heart rhythm . turning to fig2 the solid line of the membrane 14 shows the membrane 14 after withdrawal of fluid from the space 16 . the phantom line shows the membrane 14 after introduction of fluid into the space 16 and expansion of the membrane 14 . a general explanation of heart assistance utilising aortic counter - pulsation can be found in the applicant &# 39 ; s international pct patent application no . pct / au00 / 00654 , now entitled “ heart assist devices , systems and methods ”, which is incorporated herein by cross - reference . returning to fig1 the device 10 is shown positioned in the ascending aspect 20 of a patient &# 39 ; s aorta 22 . fig1 also shows that the device 10 is attached to the inside wall of a stent - graft formed form an expandable frame 24 . the frame 24 is covered with a fabric , such as dacron , or other external coating such as teflon around its periphery on either the outside or the inside of the frame 24 . the wires of the frame 24 are bare adjacent any vessels branching off from the aorta 20 so that such vessels are not occluded . it should also be noted that the shell 12 extends around only a part of the circumference of the frame 24 and any part of the frame 24 over which the shell 12 or membrane 14 does not extend are formed bare , again to avoid occlusion of any branching vessels diverging from the aorta 20 . the frame 24 may be self expanding and formed of a spring material or of a shape memory alloy such as nitinol . alternatively , the frame 24 may be expandable under the influences of the expansion of the membrane 14 , as will be describe [ sic ] in more detail below . in another alternative a conventional balloon catheter could be used to expand the frame 24 . as best seen in fig2 under normal operating conditions , the membrane is expanded ( see phantom line ) to a diameter less than that of the expanded frame 24 . accordingly , to expand the frame 24 with the membrane 14 , the membrane 14 is initially expanded by a larger than normal amount and then a lesser amount of expansion is used in counter - pulsation with the patient &# 39 ; s heart . the frame 24 , the shell 12 and the membrane 14 are packaged into a catheter delivery structure ( not shown ) which can be introduced into the aorta 20 . such structures are well known to persons skilled in the art and shall not be described in any more detail . [ 0033 ] fig3 and 4 show a patient after the frame 24 has been placed intraluminally and then connected to a drive mechanism 26 . this is done by forming an aperture 28 ( see fig4 ) in the wall of the aorta 20 and connecting a fluid connecting tube 30 from the drive mechanism 26 to the inlet / outlet port 18 of the device 10 . more particularly , the fluid connecting tube 30 is a gas carrying tube which exists [ sic ] the body percutaneously at the opening 32 and the drive mechanism 26 is a suitable pneumatic driver . [ 0034 ] fig5 shows an alternative arrangement in which the frame 24 is positioned through a stab would in the aorta , preferably the ascending aorta . in this case the aorta is approached through a sternotomy . a purse string 33 is then placed around a site for a stab incision and drawn tight around the catheter used for placement of the frame in the aorta . in this embodiment , a driver 34 may be connected to the device prior to the placement of the device in the aorta . suitable hydraulic drivers are disclosed in the applicant &# 39 ; s international pct patent application no . pct / au02 / 00974 entitled “ a fluid pressure generating means ”, which is incorporated herein by cross reference and are capable of cyclically inflating and deflating the space 16 . the driver 34 may be connected to one end of the shell 12 , as is shown in fig5 or intermediate its ends . the embodiments of the invention described above possess a number of major advantages over prior art devices . firstly , by positioning and holding the shell 12 of the device 10 against a wall of the aorta , the blood contacting surfaces of the device 10 are minimised as blood is not able to flow over the surfaces of the shell 12 adjacent the aorta wall . secondly , where a patient has a vasculature that requires the expansion and / or support of a stent , and also a heart that requires the assistance of an inflatable counter - pulsation heart assist device , then both these objectives can be achieved with only a single surgical procedure , thus reducing the risk of surgical complications . further , in some embodiments , the heart assist device itself can also be used to expand the stent . the devices may be placed with limited surgical intervention as compared with , for instance , the aortic patch . if there were plaque present in the aorta of a patient it may be possible to immobilise this plaque when placing the device bt trapping the plaque between the device and the aortic wall . while the embodiments described above have been described in relation to positioning of an intraluminal inflatable counter - pulsation heart assist device within the ascending aorta , it would be appreciated by persons skilled in the art that such devices can be positioned in other parts of the aorta or in other arteries to assist in heart function . the heart assist devices described above are suitable for short and long term treatment for heart failure and / or myocardial ischemia . it would also be appreciated by persons skilled in the art that numerous variations and / or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as before described . the present embodiments are , therefore , to be considered in all respects as illustrative and not restrictive .
apparatus and method for performing a heart assist function by use of intraluminal inflatable counter - pulsation balloon or chamber . the apparatus includes means to hold the balloon or chamber in place against an inner wall of a blood vessel . the balloon or chamber is connected to a source of pressure which expands and contracts the balloon in counter - pulsation with the heart .