Catheter

Abstract

A catheter for the creation of an atrial septal defect without thoracotomy. The catheter comprises a main flexible tubular housing and a branch tubular housing. A flexible guide wire extends through the main housing and is secured at the distal end thereof and extends outwardly of the distal end. The guide wire can be deformed into a dome shape protruding from a slit opening in the distal end of the main housing by advancing the guide wire from the proximal end of the main housing. A tiny surgical blade disposed in the slit opening of the main housing is elevated to a desired angle by advancing a flexible control wire pivoted to the blade and extending through the main housing. The branch tubular housing communicates with the main housing and is adapted for connecting a syringe or pressure gauge. A pair of rubber stoppers are provided on the main housing.

Description

My invention relates to catheters in general, and in particular to a novel catheter for the creation of an atrial septal defect without thoracotomy.

For the past two decades, surgical creation of atrial septostomy has been known to be a palliative procedure in certain types of congenital heart disease, particularly in the transposition of the great arteries. However, this procedure carries a significant surgical mortality. After the introduction of a new catheter, namely the "Balloon Catheter" in 1966 by Rashkind, atrial septostomy without thoracotomy or opening of the chest wall surgically become possible. This catheter is equipped with an inflatable balloon at the catheter tip. In order to use this procedure, the catheter is advanced into the heart through a peripheral vein, usually the femoral vein. The catheter tip is then advanced into the left atrium through the patent foramen ovale, naturally existing hole in the atrial wall, under fluoroscopic control. The balloon at the catheter tip is inflated with a radium-opaque contrast material. Pulling this balloon catheter out abruptly and forcefully results in the breakage of the atrium septum.

Since the introduction of the balloon technique, mortality of patients with congenital heart diseases, such as the transposition of the great arteries in early infancy, has been reduced and a number of infants were saved at a life-threatening critical moment. The grim outlook for those patients has been brightened.

The use of this balloon catheter was promptly popularized with a great deal of enthusiasm. After several years of experience with the balloon catheter some technical and mechanical difficulties were encountered. Also, a few complications in use of this catheter were reported.

The original inventor of the balloon catheter, Dr. Rashkind, described theoretical problems in the use of the catheter in his original paper in 1966. Listed problems were as follows: (1) inability to pass the catheter through the patent foramen ovale, (2) The left atrium being too small to allow balloon inflation, (3) impairment of the return of venous blood due to slow emptying of the balloon, (4) rupture of the balloon, and (5) misplacement of the balloon into the right ventrical or other chamber.

Subsequently, other investigators reported complications: (1) inability of deflation of the balloon while the catheter tip was still inside of the heart, (2) fatal systemic arterial embolization (occlusion) by a fragment of rubber, as a result of rupture of the balloon during the procedure--the occlusion of the renal artery on one occasion and the cerebral artery involvement in another.

Furthermore, recent studies indicated that passage of the balloon through the foramen ovale has to be performed rapidly since the balloon shuts off the entire systemic output, which resulted in a precipitous drop of arterial pressure. A longer occlusion of the foramen ovale by the balloon may result in severe bradycardia, a slowing of the heart rate.

Current balloon atrial septostomy requires multiple pulls with vigorous and rapid force which undoubtably enhances the probability of the above complications and trauma to the adjoining the cardiac tissue.

Not infrequently, in spite of multiple pulls with the balloon catheter, adequate atrial septostomy could not be created. The reason for this failure could be an anatomically unusually thick atrial septum and mechanical or technical inadequacies.

The aim of the invention is to eliminate previously noted complications in the use of the balloon catheter and to carry out the atrial septostomy more effectively.

The primary object of the invention is to create an atrial septal defect in infants with various congenital heart disease, particularly of cyanotic variety, without a thoracotomy. Furthermore, the usage of the catheter may extend to valvulotomy in either valves of the great vessels or the atrio-ventricular valves.

Another object of the invention is to create a palliative atrial septostomy for certain type of the congenital heart disease, whereby risky thoracotomy may be eliminated in critically ill newborns and young infants.

Yet another object is to make possible the performance of a valvulotomy for either a therapeutic or an experimental purpose without a thoracotomy which is, at times, too dangerous to a critically ill patient and alters a great deal of hemodynamics and physiology.

This and other important objects of the invention will become apparent from the study of the following description and the accompanying drawing.

It is to be understood, however, that these are given by way of illustration and not as a limitation and that various changes in detail construction, size and shape of parts may be made within the scope of the invention.

In the drawing:

FIG. 1 is a perspective view of the catheter in nonoperative position;

FIG. 2 is an enlarged detail view in vertical cross-section of the distal part of the catheter in non-operative position, the operative position being shown in dotted lines;

FIG. 3 is a top plan view of the same;

FIG. 4 is a schematic view, partly in section, illustrating the catheter in operative position in a heart, just prior to an incision, and

FIG. 5 is an enlarged partial detail of the catheter shown in FIG. 4.

Referring now to the Figures in detail, the catheter, generally indicated by the numeral 6, comprises a long round thin walled polyethylene housing tube 8, 14 inches in length with a diameter of French No. 5, which may vary from No. 4 to No. 6. The proximal part of the catheter is branched or Y-shaped into two portions, branch 10 and 12. The branch portion 10 is 11/4 inches long and the branch portion 12 is a 23/4 inches long. The two branch portions are secured with a plastic Y-fitting 11 or molded integrally with one another, branch 12 being used for connecting a syringe or pressure gauge. The tip 14 of the catheter is provided with a slit 16 on the long axis of the catheter. The slit is 0.75 inch long and 0.031 inch wide. The catheter is equipped with a tiny surgical blade 18, a control wire 20 pivoted to one end of the blade at 22 and a guide wire 24. The distal portion of the guide wire is a very fine coiled spring of flexible wire, which has a diameter of 0.025 inch. The flexible part of the guide wire is permanently secured in the forward portion of the tip of the catheter. An end 30, measuring 0.31 inch, of the wire protrudes outwardly of the catheter tip 14. The guide wire is disposed in the slit above of the blade 18. The flexible portion 21 of the wire extends 2 inches backwards from its securement point in the catheter tip, and the remainder of the guide wire is stiffened by a solid wire reinforcement inside of the coil spring wire.

As shown in the Figures the fine tiny surgical blade 18 measuring 10mm .times. 0.8mm .times. 0.3mm is linked at its other end at 26 to one end of a lever 28 of stainless steel. The other end of the lever is pivoted to the wall of the catheter housing at 31 and is made of fine stainless steel wire 0.010 inch in diameter which remains inside of the catheter housing.

Both the blade control and the guide wires extend outwardly through the short branch 10 of the catheter 11/2 inches and 2 inches, respectively. The free ends of the wires are looped to form a round ring shape 32 for the guide wire and a triangular shape 34 for the blade wire. These loops serve as grips for the wires and also by their shapes provide their identifications. The long branch 12 is to be used in known manner for fluid infusion through the catheter and also for pressure measurement.

A pair of short rubber stoppers 36 and 38 are secured to the catheter housing one located in the middle of branch 10, the other just distal to the Y-fitting. These stoppers function by simple clamping with conventional hemostat clamps (not shown). Stopper 36 prevents a fluid leakage and pressure dissipation through branch 10. Stopper 38 is used to prevent a back flow of blood during the initial introduction of the catheter into the vessels and cardiac chamber.

MANIPULATION OF THE CATHETER

The catheter is introduced into the vessels, usually via the femoral vein 31, by the conventional cutdown technique. Then the catheter is advanced into the left atrium 25. The flexible part 21 of the guide wire is then advanced towards the catheter tip to form a dome-shaped loop 40. By gently moving the catheter back and forth an idea of the size and location of the septum 23 can be learned.

After the location of the septum is determined, the guide wire loop 40 can be readjusted to the desired direction, by simply rotating the entire catheter, to make the incision in the septum. The blade control wire 20 is then advanced to form an inverted "V" protrusion, as shown in dotted lines in FIG. 2. The angle and height of the blade can be adjusted as clinically indicated.

To make the incision in the atrial septum, the entire catheter is slowly withdrawn until the blade 18 crosses the atrial septum. After his maneuver, control 20 is retracted to fold the blade into the catheter, then similarly, the guide wire 24 is retracted to its original longitudinal position. Thus, the catheter may be re-advanced again into the left atrium and a dome-shaped loop formed again. By using the guide wire loop 40, the result of the incision may be evaluated. Depending on the result, the same procedure may be repeated in the same sequence to obtain the optimal result.

After the desired incision has been made and prior to total withdrawal of the catheter, both the wire loop and the blade must be folded back inside the catheter, into the initial non-operative position shown in FIG. 2 to prevent damage to the vein during the withdrawal.

The pressure branch 12 of the catheter serves as a route of fluid or contrast material administration, pressure measurement and blood sampling for oxymetry, through the catheter. Another important role of the pressure branch of the catheter is to prevent a blood clotting interiorly of the catheter system by a continuous drip of the anticoagulated fluid.

In order to measure the pressure of the cardiac chamber or vessel in which the catheter tip is placed, the guide wire 24 should first be pushed inward to open the side hole of the catheter tip. Then the rubber stopper 36 is clamped with a hemostat to prevent a pressure dissipation through the wire control branch. A pressure gauge (not shown) is then connected to the pressure branch 12 of the catheter.

In order to clean the guide wire control branch 10 of the catheter, the rubber stopper 38 is first clamped, the flushing fluid is then injected into the pressure branch 12 of the catheter.

This newly devised catheter can be used for atrial septostomy more effectively and eliminates the complications currently arising with the use of the balloon catheter.

1. This catheter is equipped with a flexible wire tip which minimizes the trauma or perforation of the cardiac wall or vessels during the manipulation of the catheter, also, the wire tip would decrease the chances of crossing any intra-atrial communication, such as the patent foramen ovale, even in the presence of a very small hole.

2. The space occupied in the left atrium by the catheter, including the wire loop and blade in the cardiac chamber, is negligible; therefore, the hazard of venous obstruction which occurs with the inflated balloon is eliminated. Also, even in the presence of a small left atrium, atrial septostomy could be performed.

3. Compared to the blind and forceful atrial septostomy by a balloon catheter, this catheter is capable of performing an incision on the atrial septum accurately in the desired direction and location. This procedure requires practically no force, which eliminates, with certainty, unnecessary trauma in adjoining tissue.

4. There is no problem with embolization by a foreign body, which has occurred in the use of the balloon catheter as a result of the rupture of the balloon.

5. Misplacement of the catheter into other cardiac chambers can be detected by careful examination of the guide wire loop and by direct pressure measurement.

ADVANTAGES OF CONSTRUCTION

1. size and manipulation of the catheter is practically identical as conventionally utilized ones.

2. Because the catheter is equipped with a flexible guide wire tip and loop, manipulation of the catheter is more convenient and the chance of entering the stenotic area (valve) of the heart is increased.

3. The guide loop wire will serve as an indicator of the direction of the scalpel which allows a precise incision of the tissue. Also the loop will be used in determination of a location or size of the septum or valves. An additional virtue of this loop wire is to prevent an inadvertent damage of the surrounding tissue as the blade is in use.

4. The height of the blade is easily adjustable.

Claims

I claim

1. A catheter for the creation of an atrial septal defect without thoracotomy, comprising, in combination, a main tubular housing of flexible material having an open end and a closed end tip formed with an elongated slit open portion, a flexible guide wire displaceable longitudinally in said main tubular housing, one end of said guide wire extending outwardly through said open end, the other end of said guide wire being secured in said closed end tip and extending outwardly thereof, said other end of the guide wire having a distal part lying within said open slit portion and being deformable into a dome-shaped protrusion upon advancing said guide wire in the direction of said closed end tip, a flexible control wire displaceable axially of said main housing and having a proximal outwardly extending end, a blade having one end pivoted to the distal end of said control wire, link means pivoted to the other end of said blade and to said closed end tip, said blade and said link means being normally disposed in said slit open end and deformable into V-shape upon advancing the control wire in the direction of the closed end tip, a branch tubular housing communicating with said main housing and having a free end adapted for connecting a syringe or pressure gauge, first and second stoppers of resilient material secured, respectively, about the main housing forwardly and posteriorly of said branch housing for applying hemostats to prevent fluid leakage, pressure and back flow of blood during the initial introduction of the catheter into the vessels and cardiac chamber of a patient.

2. A catheter as claimed in claim 1, wherein said guide wire consists of a fine coiled spring wire, and a flexible solid wire secured in said coiled spring wire inwardly of the proximal part of said guide wire.

3. A catheter as claimed in claim 2, wherein the one end of said guide wire extending from said flexible tubular housing terminates as a ring-shaped handle.

4. A catheter as claimed in claim 3, wherein the proximal outwardly extending end of said control wire terminates as a triangular-shaped handle, for easy identification of the control wire.