Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
1998-12-02
2001-06-19
Seidel, Richard K. (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S151000
Reexamination Certificate
active
06248091
ABSTRACT:
The present invention refers to a balloon catheter adapted for insertion into a blood vessel to, for example, expand obstructions in vessels or to temporarily isolate a portion of the blood vessel wall from contact with the blood flow.
Balloon catheters are known comprising a catheter hose having its distal end provided with a tubular balloon support with an angular balloon fitted thereon. A lumen extending through the catheter hose communicate the balloon with an extracorporeal pressure source. The balloon is expanded by feeding a pressurized liquid thereinto. A complete obstruction of the blood vessel usualy occurs in doing so, resulting in an inadequate supply (ischemia) to the downstream organ regions. To avoid this, perfusion catheters (circulation catheters) are used. Among these are auto-perfusion cathaters (DE 92 07 395 U1) with a passage through the balloon support so that blood can circulate through the interior of the angular balloon, as well as active perfusion systems, wherein an external high-pressure pump connected to the distal cathater end provides for a continuous perfusion through the interior of the cathater. In contrast to auto-perfusion cathaters, active perfusion systems actively develop a particular pressure that is independent from the momentary blood pressure of a patient. To do so, however, arterialized blood has to be drawn from the patient that is pumped outside the body into the lumen of the cathater hose. Moreover, due to the high pressure losses within the small-lumen cathater hose, very high pump pressures (up to about 12 bar) are necessary to convey about 40 to 60 ml/min.
From U.S. Pat. No. 4 969 865, an intravascular blood pump for cardiac support is known. This blood pump may be introduced into the heart through a blood vessel. It comprises an elongate tube accommodating a screw-type impeller driven by a flexible shaft. This pump has an axial intake and has its opposite outlet end provided with holes for the radial outflow. In operation, the blood pump is positioned in the opening of the cardiac valve, with the intake end being located in one of the cardiac ventricles, while the delivery end is disposed in the aorta.
It is an object of the present invention to provide a balloon cathater that forms a simplified active perfusion system.
According to the invention, the object is solved with the features of claim
1
.
In the present balloon cathater, a pump is disposed in the course of the cathater, in particular at a position proximal of the balloon support. Through appropriate openings, the pump draws blood laterally from the blood vessel and pumps is axially through the balloon support. Since the pump is disposed just in front of the balloon support, only a relatively low pump pressure is required. The pump is small enough to be located in the cathater immediately in the area of the surgical operation, i.e. close to the balloon, so that the length of the lumen to be flushed is short, thereby maintaining the pressure losses on a relatively low level. The diameter of the pump is so small that it can be inserted into the blood vessel together with the cathater, without injuring the blood vessel. Generally, smaller blood vessels are treated with balloon cathaters. The maximum diameter of the pump should not exceed about 1.4 mm. Such a small pump can be integrated into the cathater so that it is situated just in front of the balloon support extending through the site of the treatment of the blood vessel. Here, the pump draws blood in the flow direction of the vessel from the high pressure region via at least one lateral inlet and conveys the same into the low pressure region beyond the expanded balloon.
Due to the required compact size of the pump, it has to be driven at relatively high rotational speeds, so as to achieve the necessary delivery rate of, for example, 60 cm
3
/min. Preferably, the rotary speed of the pump is within the range from 80,000 to 150,000 rpm.
Preferably, the balloon cathater is used for expanding obstructions in vessels, in particular in the coronary vessel area, in the carotid artery, and the like. Yet, it is also possible to position a wire basket (stent) to distend obstructions in vessels.
Another aspect of the invention refers to a perfusion cathater comprising a plurality of serially arranged balloons. The balloons temporarily seal a length of the vessel to allow for a bypass to be sutured to this area. Blood keeps flowing through the tubular balloon support, while the sealed vessel section is available for surgery.
The invention provides an active perfusion cathater with an integrated pump. The handling of the same largely corresponds to that of passive auto-perfusion cathaters, yet its performance is similar to that of active perfusion systems. It is another advantage that the balloon support can be formed with a very small outer diameter of about 1 mm. Thus, it is guaranteed in almost any case, even with severe stenoses that the balloon portion can be placed in the stenosis.
Preferably , the pump is driven by a flexible shaft connected to a motor provided at the proximal end of the cathater hose. Such pumps comprising only a pump housing and an impeller rotatingly housed therein, can be manufactured with a very small outer diameter of about 1.5 min. In general, the invention also provides for integrating a pump motor in the cathater in the immediate vicinity of the pump, the motor directly driving the impeller wheel, in this case.
In order to place a balloon cathater in a blood vessel, a guide wire is usualy inserted over which the cathater is then pushed. Such placement using a guide wire is also possible with the present balloon cathater. Here, however, the guide wire has to be passed through the pump. The impeller of the pump or the pump itself is accordingly designed such that it allows for the passage of a guide wire having a diameter of about 0.3 mm. It should be taken into consideration that the pump is started up only after the guide wire has b e en withdrawn far enough from the immediate pump area. While placing the catheter, it is acceptable that the guide wire blocks the impeller wheel.
The following is a detailed description of embodiments of the present invention taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 4631052 (1986-12-01), Kensey
patent: 4729763 (1988-03-01), Henrie
patent: 4753221 (1988-06-01), Kensey et al.
patent: 4857046 (1989-08-01), Stevens et al.
patent: 5137513 (1992-08-01), McInnes et al.
patent: 5163910 (1992-11-01), Schwartz et al.
patent: 5628719 (1997-05-01), Hastings et al.
patent: PCT/NL92/00159 (1992-09-01), None
Fulwider Patton Lee & Utecht LLP
Seidel Richard K.
Sirmons Kevin C.
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