Methods and apparatus for anchoring an occluding member

Abstract

Pressure is measured on both sides of an occluding member for determining when pressure forces on the occluding member may cause migration of the occluding member. An alarm indicates when the pressure force on the balloon exceed a predetermined threshold. In another aspect of the invention, a pressure monitor determines when a rate of pressure increase with respect to the fluid volume in the balloon reaches a predetermined threshold when inflating the occluding member. A predetermined amount of fluid is then added to the balloon so that the balloon is not under inflated or over inflated.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a divisional of U.S. patent application Ser. No. 08 / 570,286, filed Dec. 11, 1995, which is a continuation-in-part of Ser. No. 08 / 486,216, filed Jun. 7, 1995 which is a continuation-in-part of application of copending U.S. patent application Ser. No. 08 / 282,192, filed Jul. 28, 1994, which is a continuation-in-part of application Ser. No. 08 / 162,742, filed Dec. 3, 1993, which is a continuation-in-part of application Ser. No. 08 / 123,411, filed Sep. 17, 1993, which is a continuation-in-part of application Ser. No. 07 / 991,188, filed Dec. 15, 1992, which is a continuation-in-part of application Ser. No. 07 / 730,559, filed Jul. 16, 1991, which issued as U.S. Pat. No. 5,370,685 on Dec. 6, 1994. This application is also related to copending U.S. patent application Ser. No. 08 / 159,815, filed Nov. 30, 1993, which is a U.S. counterpart of Australian Patent Application No. PL 6170, filed Dec. 3, 1992. This application is also rela...

AI Technical Summary

Benefits of technology

[0032] The second low-friction portion is preferably positioned at a radially outward position relative to the first portion so that when the balloon is advanced within the patient substantially only the low friction portion contacts the body passageway. The balloon preferably includes a number of low friction portions which are positioned at radially outward portions of at least three, and preferably at least four, arms. The high friction portion is positioned between adjacent low friction portions and, further, the high friction everts when the balloon moves from the collapsed shape to the expanded shape. The term “collapsed” as used herein refers to the overall configuration of the expandable member when the expandable member is advanced within the patient to the desired occluding position. An advantage of the present invention is that the first, high-friction portion does not contact the body passageway when the balloon is advanced within the patient thereby reducing trauma and, furthermore, reducing the risk of releasing plaque into the bloodstream.

[0033] The first portion is preferably integrally formed with the second portion and is provided with a number of ribs and / or a selective coating. A method of providing a selective coating and other methods of providing a frictional surface are described in PCT Application Number PCT / US94 / 09489 which is incorporated herein by reference. Another method of providing high and low friction portions would be to mask the low friction portion and sandblast the high friction portion. Alternatively, a mandrel which is used to make the balloon may have the high friction portion sandblasted.

[0034] The present invention provides distinct advantages over PCT Application Number PCT / US94 / 09489 since the radially-extending arms help prevent the high friction portions from contacting the blood vessel. A problem which might occur with the balloon of PCT / US94 / 09489 is that the balloon might unravel when the balloon is inserted into the patient thereby exposing the high friction portions. Conversely, if the balloon is wrapped too tight, the balloon may not open correctly when the balloon is inflated. The present invention provides high friction portions which are exposed but prevented from contacting the body passageway by the radially outward portion of the arms.

[0035] In another aspect of the invention, pressure sensors are provided on both sides of the balloon for measuring pressures exerted on the balloon. In this manner, it can be determined when a pressure differential exists across the expandable member which might move the balloon upstream or downstream. The pressure sensors are preferably coupled to an alarm which indicates when the pressure differential exceeds a predetermined threshold pressure. In a preferred embodiment, the pressure of cardioplegic fluid in the ascending aorta is adjusted to reduce the pressure differential to a value below the threshold pressure. The descriptive terms downstream and upstream refer to the direction of blood flow and the direction opposite normal blood flow, respectively. In the arterial system, downstream refers to the direction away from the heart and upstream refers to the direction toward to the heart. The terms proximal and distal, when used herein in relation to instruments used in the procedure, refer to directions closer to and farther away from the operator performing the procedure, respectively.

[0036] In another aspect of the invention, the pressure of the balloon is monitored to optimize the inflation pressure. When inflating the balloon, it is desirable to provide a high pressure so that the balloon holding force is maximized to prevent migration. On the other hand, it is desirable to minimize balloon pressure so that aortic distention is minimized. In order to provide a balloon pressure which balances these two concerns the balloon pressure is monitored until a spike in the pressure vs. fluid volume is detected. The pressure spike generally indicates that the balloon has engaged the sidewall of the passageway. After the pressure spike is detected, a predetermined amount of fluid is added or the pressure of the balloon is increased a predetermined amount so that the balloon pressure is optimized to enhance the holding force on the balloon while preventing excessive aortic distention.

[0037] In yet another aspect of the invention, the shaft of the catheter is displaced and anchored so that a portion of the shaft engages the aortic lumen for resisting balloon migration. The shaft is preferably slidably coupled to a delivery cannula for movement in both inward and outward directions. The shaft preferably includes a first portion configured to contact the radially inner wall of the aortic lumen when the shaft is slidably displaced in the outward direction. The first portion anchors the shaft which, in turn, anchors the occluding member. When the shaft is displaced in the inward direction, a second portion engages the radially outer wall of the aortic lumen. A preferred shape for the shaft includes two bends and three substantially straight portions. The first predetermined portion, which engages the radially inward wall of the aorta, is preferably positioned between the first and second bends.

Problems solved by technology

First, such isolation facilitates infusion of cardioplegic fluid into the coronary arteries to perfuse the myocardium and arrest cardiac function without allowing the cardioplegic fluid to be distributed elsewhere in the patient's circulatory system.

Second, such isolation facilitates use of a cardiopulmonary bypass system to maintain circulation of oxygenated blood throughout the circulatory system without allowing such blood to reach the coronary arteries and resuscitate the heart.

This has significant advantages over the aortic cross-clamps used in current cardiac procedures, not only obviating the need for a thoracotomy, but providing the ability to stop blood flow through the aorta even when calcification or other complications would make the use of an external cross-clamp undesirable.

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