Bi-directional perfusion cannula

Abstract

A bi-directional perfusion cannula comprising a flexible elongated tube 1 for insertion into an artery having a first aperture 3 at a distal end and a second aperture 4 formed rearward of the first aperture, the elongated tube can be bent in correspondence of the second aperture to orient it in a direction opposite to the insertion direction. The cannula is provided with a tape 5 having a first end portion shaped as a ring, fixed on an outer surface of the elongated tube, and a second end portion opposite to the first end portion either coupled to or being integral with a belt 7 defining a strap 11 with holes 12 and at least a prong 13 integral with the strap and configured to engage a respective hole, wherein the belt is configured to be tightened around an outer surface of the artery.

Claims

1. A bi-directional perfusion cannula, comprising a flexible elongated tube for insertion into an artery configured to lay longitudinally in the artery, having: a first aperture oriented forward during insertion into an artery at a first end of a distal portion of the elongated tube, said distal portion of the elongated tube being configured to lay longitudinally in the artery, said first aperture being configured so that blood can flow into the artery in a direction of insertion, a second aperture formed rearward of the first aperture at a second end of said distal portion of the elongated tube, and configured to supply blood into the artery in a second direction, said elongated tube being configured to be bent in correspondence of said second aperture in order to orient said second aperture in said second direction opposite to the insertion direction, characterized in that the bi-directional perfusion cannula comprises: a tape having a first end portion shaped as a ring, fixed on an outer surface of the elongated tube, and a second end portion opposite to the first end portion, said second end portion being either configured to be coupled to or being integral with a belt defining a strap with holes and at least a prong integral with said strap and configured to engage a respective one of said holes, said belt being made of a bio-compatible material and being configured to be tightened around an outer surface of the artery; wherein said tape is configured to allow to tighten said belt at a distance from a point of insertion of said elongated tube in the artery, so as to tighten the artery together with the distal portion of the elongated tube when said distal portion of the elongated tube lays longitudinally in the artery.

2. The bi-directional perfusion cannula of claim 1, wherein said belt being integral with a head with a pawl, configured to engage with teeth of said second end portion; said second end portion is configured to be coupled with said belt and has teeth configured to engage with the pawl of said head to form a ratchet as a cable tie.

3. The bi-directional perfusion cannula of claim 1, comprising a metal wire incorporated into the flexible elongated tube as a spiral, wherein said spiral has an augmented step in correspondence of said second aperture.

4. The bi-directional perfusion cannula of claim 1, comprising a plurality of prongs integral with said strap.

5. The bi-directional perfusion cannula of claim 1, wherein said second aperture has a sectional area up 50% of a corresponding sectional area of said first aperture.

6. The bi-directional perfusion cannula of claim 5, wherein said second aperture has a sectional area ranging between 25% and 30% of a corresponding sectional area of said first aperture.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 depicts a side view of a prior bi-directional perfusion cannula with an introducer received therein.

(2) Figures from 2a to 2h depict different views of a bi-directional perfusion cannula according to an embodiment of this disclosure, having a tape with an end portion fixed to the cannula and the opposite end portion connectable to a belt having a strap with holes and at least a prong.

(3) Figure from 3a to 3h depict different views of a bi-directional perfusion cannula according to an embodiment of this disclosure, having a tape with an end portion fixed to the cannula and the opposite end portion integral with a belt having a strap with holes and at least a prong.

DETAILED DESCRIPTION

(4) Various views of two different exemplary embodiments of a bi-directional perfusion cannula of this disclosure are depicted in figures from 2a to 2h and from 3a to 3h, respectively. The perfusion cannula comprises a flexible elongated tube 1 adapted to be inserted into an artery 2. As the prior cannula depicted in FIG. 1 the elongated tube has a first aperture at a distal end, to inject blood in the direction of insertion of the tube 1 into the artery 2, and a second aperture 4, that is more clearly shown in the sectional views of detail of FIGS. 2e and 3e. The flexible tube 1 is adapted to be bent so as the second aperture 4 can be oriented to inject blood in a direction opposite to the insertion direction of the first aperture 3 for letting blood to flow also in the retrograde direction. When in use, a distal portion of the tube 1, comprised between the first aperture and the second aperture 4, lays longitudinally in the artery 2.

(5) In order to anchor firmly the tube 1 to the artery 2, the cannula of this disclosure comprises a tape 5, made of bio-compatible material, connected from a first end to a ring 6 fixed to the tube 1, and a belt 7 tightened around the artery 2.

(6) According to the embodiment of figures from 2a to 2h, the tape 5 may be connected to the belt 7 after the tube 1 has been inserted into the artery 2. This is made possible because the belt 7 has a head 8 with a pawl 9, and the free end of the tape 5 has teeth 10 so as to engage with the pawl 9 to form a ratchet as a cable tie. With this solution, it is possible to adjust the length of the tape 5 suspended between the ring 6 and the head 8 so as to tighten it and prevent the tube 1 from slipping out of the artery 2.

(7) As an alternative, illustrated in figures from 3a to 3h, the tape 5 may be integral with the belt 7. The cannula according to this latter embodiment is simpler from a constructive point of view and easier to use than the former one, but requires an accurate positioning of the belt 7 for tightening the tape 5.

(8) For both embodiments, the tube 1 is anchored to the artery 2 by tightening the tape 5 between the ring 6 and the belt 7, and by fastening the belt 7 so as to tighten the artery 2 together with the tube 1, as shown in FIGS. 2d and 3d. In practice, the tape 5 is long enough to allow to tighten the belt 7 at a distance from a point of insertion of the elongated tube 1 in the artery 2, so as to tighten the artery 2 together with the distal portion of the elongated tube 1 that lays longitudinally in the artery 2. In this way, blood is perfused in both directions by the forward aperture 3 and by the aperture 4 directed rearward, whilst there is no risk that the tube 1 slips out of the artery 2 even if the patient is awake and is moving.

(9) In order to fasten tight the belt 7, the belt 7 has a strap 11 with spaced holes 12 and at least a prong 13, integral with the strap, configured to engage a respective hole 12. In the shown embodiment a plurality of prongs 13 are depicted, though a single prong 13 may be sufficient for holding fastened the belt 7. It is considered more convenient to have prongs 13 integral with the strap instead of having a buckle (not shown) as in common belts, because a buckle would concentrate the pressure exerted by the belt 7 in certain parts of the side surface of the artery 2, instead of letting it be distributed uniformly.

(10) Conveniently, the area of the second aperture 4 may be up to 50% of the area of the forward aperture 3. Experiments carried out using working prototypes have shown that good performances in terms of forward and retrograde blood perfusion may be attained making the ratio between the sectional area of the second aperture 4 and of the first aperture 3 range between 25% and 30%.

(11) As in the prior cannula of FIG. 1, the cannulas of this disclosure preferably incorporate a metal wire 14 spirally wound in the body of the tube 1 to make it more robust. In order to make easier to bend the tube 1 in correspondence of the second aperture 4, the metal wire 14 is wounded with an augmented step in correspondence of the second aperture 4. According to an alternative, not depicted in the enclosed drawings, instead of having a wound metal wire, the elongated tube may be reinforced with an outer bio-compatible metal cover, shaped so as to allow bending of the cannula in correspondence of the second aperture 4 whilst preventing kink of the tube. Metal covers of this type, presently used for example in the cannula marketed by Medtronic™ under the commercial name Bio-Medicus™ NextGen Cannulae, are designed to deform plastically for allowing to bend the cannula in a controlled fashion.

(12) All parts of the bi-directional perfusion cannula of this disclosure are made of a bio-compatible material, in order to be adapted to be used within human body.