Dilator For Performing Mitral And Tricuspidal Commissurotomy Per Atrium Cordis

Abstract

A dilator for performing mitral and tricuspidal commisurotomy per atrium cordis, comprising a working head with jaws and a jaw actuating mechanism, the working head being associated with a hand-operated drive through a flexible base. The working head of the dilator has a relatively rigid portion which enables the surgeon to easily pass the working head with finger guidance through tracts of any curvature, i.e., to utilize the dilator in all current methods of instrumental commissurotomy performed per atrium cordis. The working head of the dilator is distinguished by its high rigidity and strength.

Description

This invention relates to medical apparatus and particularly to the design of dilators used in performing mitral and tricuspidal commissurotomy per atrium cordis.

Widespread use is made in present-day cardiac surgery--of dilators, comprising a working head that consists of two jaws with a mechanism for bringing said jaws apart which, for the sake of brevity, will hereinafter be referred to as a jaw actuating mechanism, said working head being mounted on a rigid base secured to a hand-operated drive. The rigid base is essentially a tubular structure inside which a rod or link is passed to connect the jaw actuating mechanism with the hand-operated drive.

While in operation-- , the working head of said dilator is introduced into the cardiac mitral orifice via an operational incision in the left ventricle under the control of a finger passed through the auricular appendage of the atrium cordis sinistrum.

However, such an operational technique involves operational incisions in the heart in two zones, i.e., the left ventricle and the auricular appendage of the atrium cordis sinistrum.

Such an operation can cause hemorrhage, thromboembolism, reflex cardiac arrest and other complications.

Known in the surgical art are also dilators for "per atrium cordis" commissurotomy of the mitral and tricuspid valves, wherein their working head is made fast to the hand-operated drive by means of a flexible base which accommodates a flexible rod or link connecting the jaw actuating mechanism with said hand-operated drive. Such a dilator due to its flexible base enables its working head to be introduced under finger guidance into the heart being operated and, unlike dilators featuring a rigid base, it involves only cardiotomic operation per atrium cordis and only within a single cardiac zone, which is conducive to minimize loss of blood during operation, precludes and or substantially diminishes the risk of such complications as primary cardiac arrest, valvulorrhexis, and thromboembolisms.

The above-described dilator with a flexible base, however, features a relatively longer rigid portion thereof when in a closed state which depends upon the length of the jaws and protective elements, said elements being essentially guard strips interconnecting the ends of jaws with the flexible base, which makes it impossible to successfully employ the dilator to gain access to the cardiac valve involved via the auricular appendage of the atrium cordis sinistrum, this technique being practised by a great and overwhelming majority of surgeons in performing mitral commissurotomy, since the operational tract along which the dilator working head is to be introduced, is of considerable curvature.

A reduction of the length of the rigid portion of the dilator cannot be obtained by merely decreasing the length of the jaws and guard strips which constitute the overall length of the dilator rigid portion, since the size of said strips and the length of jaws depend upon the length of the arms of the jaw actuating mechanism, while the shortening of said arms will result in a decreased span or amount of jaw opening which is not permissible.

On the other hand, to make said guard strips flexible in the afore-described dilator is not permissible since due to the fact that the arms of the jaw actuating mechanism are articulately connected at the rear ends of the jaws, the pathways of the articulated joints of the guard strips when moving towards the jaws are so directed that the opposite ends of said strips should slide along the flexible base, whereas the guard strips should on the same account work in compression in order to overcome forces of friction against said flexible base.

Furthermore, the working head of the construction adopted in the known dilator possesses but inadequate rigidity and strength.

It is an object of the present invention to provide such a dilator for performing mitral and tricuspidal commissurotomy per atrium cordis that has a minimized length of the rigid portion of its working length, whereas its jaw actuating mechanism possesses a sufficient strength and rigidity, whereby the dilator is suitable for preforming safe and effective operations of commissurotomy with all possibilities of utilizing all hitherto known ways of gaining peratrial access to the mitral and tricuspid valves (viz. through the auricular appendage, left wall of the atrium cordis or via the interatrium septum).

To accomplish this object, in a dilator for performing mitral and tricuspidal commissurotomy per atrium cordis, comprising a working head having jaws of a trough-like shape with protective elements and an articulated linkage of the jaw actuator, said working head being interconnected with a hand-operated drive through a flexible base and an elastic link or rod accommodated thereinside, according to the invention the interior lateral areas of the jaws serve as guideways for the arms of the jaw actuating mechanism, while the articulated joint of the arm of said jaw actuating mechanism in each of the jaws is located in its front portion and said protective elements are made flexible and fixed with their ends to said flexible base.

Said protective elements are preferably made as coiled springs working in tension.

Said arms of the jaw actuating mechanism are preferably arranged symmetrically with respect to the plane in which the jaws are brought apart and which passes through a longitudinal axis of the working head.

In what follows the invention is made more evident from a consideration of a description of embodiments thereof with due reference to the accompanying drawings, wherein:

FIG. 1 is an elevation view of a dilator for performing mitral and tricuspidal commissurotomy per atrium cordis, according to the invention;

FIG. 2 is a sectional view of the working head of the dilator when open, taken on enlarged scale;

FIG. 3 is a section taken along line III--III of FIG. 1 on an enlarged scale; and

FIG. 4 illustrates in elevation view an embodiment of the hand-operated drive for the dilator of the invention.

Now referring to FIG. 1, the dilator of the invention comprises a working head 1 associated through a flexible base 2 with a hand-operated drive 3. As can be seen from FIG. 1 jaws 4 and 5 of the working head 1 when closed, contact each other to form an enclosure or casing for a jaw actuating mechanism 6 (FIG. 2). The mechanism 6 comprises arms or links 7, 8, 9 and 10. The arms 7 and 8 are attached to a sleeve 13 by means of articulated joints 11 and 12, and to the jaws 4 and 5 through articulated joints 14 and 16. The arms 9 and 10 are attached to a slide member 16 by means of articulated joints 17 and 18, while their respective ends 19 and 20 are free to slide along the inner surfaces of the jaws 4 and 5 so that the lateral walls of the jaws serve as guideways for the arms 9 and 10. The arms 7 and 8 are constituted as double levers (FIG. 3) which straddle the arms 9 and 10 in such a way that the arms of the jaw actuating mechanism 6 are arranged symmetrically with respect to the plane A--A (FIG. 3) in which the jaws are brought apart and which passes through the longitudinal axis of the working head, whereby the jaw actuating mechanism acquires rigidity and strength.

Slots 21 and 22 are provided in the jaws 4 and 5 (FIG. 2) to serve as guideways for the arms 9 and 10 as well. Connected to the jaws 4 and 5 and to the flexible base 2 are elastic protective elements 23 which are essentially coiled extension springs adapted to protect the working head 1 against possible catching on cardiac tissue when it is being opened.

The flexible base 2 is secured in the sleeve 13. Extending inside the flexible base 2 is a rod 24 which is fixed in place on in the slide member 16. The opposite ends of the flexible base 2 and of the rod 24 are secured to respective handles 25 and 26 (FIG. 1) of the hand-operated drive 3.

The rod 24 may be made of an elastic steel wire or of a stranded steel wire in dependence upon the required degree of its elasticity. Thus, when introducing the dilator per the auricular appendage of the atrium cordis sinistrum, use is made of a rod made of stranded steel wire, whereas if the dilator is to be introduced through the interatrium septum from the right (dextrolateral access) use is made of a rod made of elastic steel wire.

The flexible base 2 is made of a wound spring-steel wire and is provided with a locknut 27 at the place of its attachment to the handle 25, whereby the working head 1 can be set in any plane with respect to the hand-operated drive 3.

The hand-operated drive 3 is provided with a stop 28 for limiting the degree of opening of the working head 1, an indicator 29 of the degree of opening of the working head 1 and return springs 30.

The hand-operated drive 3, (FIG. 4) is more suitable for use when performing mitral commissurotomy by the dextrolateral access. When utilized in transauricular sinistrolateral access, use is made of the hand-operated drive 3 represented in FIG. 1.

For tricuspidal commissurotomy, use can be made of any of the above-stated hand-operated drives.

The dilator of the present invention is operated as follows.

When bringing the handles 25 and 26 together (FIG. 1) the rod 24 causes the slide member 16 (FIG. 2) to move towards the sleeve 13, while the jaw actuating mechanism 6 brings the jaws 4 and 5 apart. The degree of opening or span of the jaws 4 and 5 is monitored by the indicator 29 associated with the handles 25 and 26 (FIG. 1). Both jaws 4 and 5 are caused to return to their initial position under the effect of the return springs 30.

While in operation the dilator functions as follows: in performing mitral commissurotomy, the working head 1 is introduced into the heart's interior under finger guidance on the side of the atrium cordis sinistrum and is set under finger control in the mitral orifice. Bringing of the handles 25 and 26 of the hand-operated drive 3 together the working head 1 is caused to open which, in turn, effects separation of the concreted cusps of the mitral valve, i.e. in commissurotomy. Whenever necessary, the working head 1 of the dilator can be set in any plane with respect to and to suit the position of the commissures to be operated. The operation of commissurotomy with the use of the present dilator ensures an adequate dilation of the valve orifice, minimizes the operational trauma inflicted upon the cardiac valvular apparatus and the loss of blood during operation.

In the case of tricuspidal commissurotomy, the dilator can be introduced under finger guidance through the auricular appendage of the atrium cordis dextrum and through the wall of the latter. The elimination of the tricuspidal stenosis is similar to the mitral commissurotomy.

The dilator disclosed herein is successfully applicable to all the up-to-date methods of peratrial instrumental commissurotomy, this being due to the fact that the dilator of the invention is favorably compared to all hitherto known dilators as regards minimum length of the rigid portion of its working head which length depends only upon the length of the jaws; thus, the working head can be easily introduced and passed under finger guidance through tracts of any curvature.

The present dilator possesses a higher rigidity and sturdiness as compared to the dilators used heretofore and can sustain a load of up to 100 kg when in open state, whereas the maximum load for the known dilator with the flexible base is not more 8 to 10 kg.

Furthermore, a tight and snug adherence of the arms of the jaw actuating mechanism to the inner lateral surfaces of the jaws along with a symmetrical arrangement of the arms of said mechanism with respect to the plane in which the jaws are brought apart, ensure minimum free play and an increased rigidity of the dilator working head.

The herein-proposed dilator is of a sectionalized construction which allows preventive maintenance and replacement of worn-out or faulty components which, in turn, adds much to the service life.

The present dilator has been made employed in performing 65 operations in patients afflicted with mitral stenosis with no complications or fatal results. The obtained results enable the dilator of the present invention to be regarded as a valuable contribution to the sphere of surgical instruments used in cardiac surgery.

Claims

What is claimed is:

1. A dilator for performing mitral and tricuspidal commissurotomy per atrium cordis, said dilator comprising a working head including trough-shaped jaws, a lever mechanism coupled to said jaws for opening and closing said jaws, said lever mechanism including two groups of levers, the levers of one of the groups being articulated to one end of said jaws, the levers of the other group being freely slidable along the inner lateral surfaces of said jaws adjacent the other end of said jaws, serving as guideways for said levers, a hand-operated drive means coupled to said lever mechanism to operate the same, a flexible base connecting the other ends of the levers of said one group to said hand-operated drive means, a flexible link accommodated inside said flexible base and connecting the other ends of the levers of said other group with said hand-operated drive means, and elongated spring elements connected at one end thereof to the jaws and at the other end thereof to the flexible base, one lever of each group being pivotally connected to a lever of the other group intermediate the ends thereof.

2. A dilator as claimed in claim 1 wherein said spring elements are connected to the jaws at the ends thereof remote from the ends at which said one group of levers are connected to said jaws.

3. A dilator as claimed in claim 2 wherein said protective elements are connected to the jaws proximate the said guideways.

4. A dilator as claimed in claim 1 wherein said jaws have a longitudinal plane of symmetry and said two groups of levers are symmetrically disposed with respect to said plane.

5. A dilator as claimed in claim 4 wherein said one group of levers include arms straddling the levers of said other group.

6. A dilator as claimed in claim 1 wherein said trough-shaped jaws are hollow and when closed are in contact with one another and define an enclosure in which the lever mechanism is completely enclosed.

7. A dilator as claimed in claim 1 wherein said spring elements are constituted as coiled extension springs.