Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M25/00—Catheters; Hollow probes
  • A61M25/0067—Catheters; Hollow probes characterised by the distal end, e.g. tips
  • A61M25/0068—Static characteristics of the catheter tip, e.g. shape, atraumatic tip, curved tip or tip structure
  • A61M25/007—Side holes, e.g. their profiles or arrangements; Provisions to keep side holes unblocked
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M1/00—Suction or pumping devices for medical purposes; Devices for carrying-off, for treatment of, or for carrying-over, body-liquids; Drainage systems
  • A61M1/36—Other treatment of blood in a by-pass of the natural circulatory system, e.g. temperature adaptation, irradiation ; Extra-corporeal blood circuits
  • A61M1/3621—Extra-corporeal blood circuits
  • A61M1/3653—Interfaces between patient blood circulation and extra-corporal blood circuit
  • A61M1/3659—Cannulae pertaining to extracorporeal circulation
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M25/00—Catheters; Hollow probes
  • A61M25/0043—Catheters; Hollow probes characterised by structural features
  • A61M25/005—Catheters; Hollow probes characterised by structural features with embedded materials for reinforcement, e.g. wires, coils, braids
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M25/00—Catheters; Hollow probes
  • A61M25/0021—Catheters; Hollow probes characterised by the form of the tubing
  • A61M25/0023—Catheters; Hollow probes characterised by the form of the tubing by the form of the lumen, e.g. cross-section, variable diameter
  • A61M25/0026—Multi-lumen catheters with stationary elements
  • A61M25/003—Multi-lumen catheters with stationary elements characterized by features relating to least one lumen located at the distal part of the catheter, e.g. filters, plugs or valves
  • A61M2025/0031—Multi-lumen catheters with stationary elements characterized by features relating to least one lumen located at the distal part of the catheter, e.g. filters, plugs or valves characterized by lumina for withdrawing or delivering, i.e. used for extracorporeal circuit treatment

Definitions

• the present invention relates to cannulas used in draining venous blood for surgical procedures requiring cardiopulmonary bypass. More particularly, the present invention is directed to a venous return cannula adapted for use in draining blood from the right atrium and the vena cavae with enhanced drainage for minimally invasive surgery.
• Venous blood depleted in oxygen and rich in carbon dioxide is removed from the patient and pumped to an oxygenating apparatus in order to oxygenate the blood and remove excess carbon dioxide.
• the blood is then returned to the patient's arterial system.
• One such technique involves placement of a pair of cannulas, one into the superior vena cava, and another into the inferior vena cava, in order to collect venous blood returned to the patient's right atrium.
• This technique is extremely reliable but suffers from the disadvantage that it takes time to surgically place two cannulas, and then to suture the insertion locations when the cannulas are removed following bypass. Nevertheless, because of problems experienced in connection with conventional single cannula designs discussed below, some physicians continue to utilize a two cannula technique.
• a second general technique involves placement of a single cannula. Many physicians prefer a single cannula technique over a two cannula technique because only one incision is required, thereby simplifying and shortening the cannulation procedure both at the time of insertion and at the time of removal. It is also helpful to reduce the number of cannulas that a surgeon must work around as he conducts surgery on the patient.
• One variation of the single cannula technique involves placement of a cannula so that its distal tip lies in the right atrium. Such a placement permits the cannula to collect blood draining into the right atrium from the inferior vena cava and from the superior vena cava. While this procedure is capable of achieving adequate venous drainage, on occasion the cannula tip is overinserted or otherwise inadvertently manipulated so that the drainage openings in the cannula are pressed against tissue within the right atrium, thereby reducing or even interrupting blood flow into the cannula. This can be extremely dangerous to the patient. Because of these dangers, only a relatively small number of physicians utilize this procedure.
• a second variation of the single cannula technique is a hybrid of the two cannula and single cannula techniques described above.
• a single cannula is provided having drainage openings not only at the distal end, but also along its length proximal to the distal end.
• Such a cannula sometimes referred to as a "dual drainage" cannula, is then inserted through the right atrium and into either the inferior vena cava or the superior vena cava, with the proximal drainage openings positioned within the right atrium. This placement permits blood to be drained simultaneously from the vena cava in which the dual drainage cannula is placed and from the right atrium.
• conventional dual drainage cannulas have a multi-diameter structure, with a relatively small diameter distal cannula portion (e.g., 36 French) and a larger diameter proximal portion (e.g., 51 French).
• Such cannulas are typically constructed by forming a molded reducer having elongate slots therein, and then affixing suitable lengths of 36 French and 51 French tubing to opposite sides of the reducer.
• the distal portion of the cannula is inserted only partially into one of the vena cavae so that the proximal drainage openings remain substantially centered within the right atrium.
• the cannula is overinserted, occasionally so much so that the proximal drainage openings are partially occluded at the entrance to the vena cava, or are actually inserted into the vena cava so that both distal and proximal drainage openings drain from the vena cava, and none drain the right atrium. This results in a substantial reduction in venous drainage.
• a dual drainage cannula is used by inserting it through the right atrial appendage and then into the inferior vena cava. Since the inferior vena cava is not directly opposite the right atrial appendage, placement of a cannula using this conventional placement technique results in a bend of about 30 degrees in the distal portion of the cannula.
• venous return cannula is positioned within the venous return side of heart, and connected with a venous reservoir that is placed below the level of the operating table.
• venous blood is removed from a patient and circulated through the bypass system.
• vacuum- assisted drainage systems typically include a hard-shelled venous reservoir to which a source of vacuum is connected, and into which the venous return cannula terminates.
• a negative pressure within the hard-shelled reservoir is transmitted along the venous return cannula to produce a suction at the distal tip apertures.
• Various benefits are realized by vacuum-assisted venous drainage, including the potential for reduced tubing and prime volume because the venous reservoir no longer needs to be positioned below the operating table to establish a pressure head.
• smaller cannulas can be utilized because of the active suction of the venous blood.
• Gravity-assisted drainage requires relatively large bore cannulas for adequate flow. The option of reducing the cannula bore size when using vacuum-assisted drainage facilitates moderate minimally invasive procedures, in which all of the components entering the heart through small passages are desirably reduced in size.
• USPN 4,639,252 to Kelly, et al. the entire disclosure of which is incorporated herein by reference.
• This patent discloses a venous return cannula having a first diameter distal portion suitable for insertion in a vena cava, a second, larger diameter proximal portion, and a transition portion forming a smooth transition between the first and second diameter portions. Drainage openings are provided in both the proximal and distal cannula portions. The cannula is also provided with wire reinforcement.
• the cannula disclosed in the Kelly patent is suitable for conventional gravity-assisted open heart surgeries in which the heart remains relatively stationary, there is a need for increased drainage during procedures in which the heart is substantially manipulated by the surgeon.
• Figure 1 illustrates a venous drainage cannula 20 of the prior art positioned within the right atrium (RA) and inferior vena cava (IVC) of the heart of a patient.
• the cannula passes through an aperture 22 created in the right atrial appendage (RAA) that is sealed around the cannula using purse string sutures 24.
• RAA right atrial appendage
• SVC superior vena cava
• the cannula 20 extends from a proximal end 30 to a tapered distal tip 32 having a distal port 34.
• the body of the cannula 20 is tubular and may be of a relatively constant diameter, or may have a stepped diameter.
• a plurality of suction holes is provided through the wall of cannula 20 for venous drainage. More particularly, a plurality of distal suction holes 36 are provided in a segment adjacent the distal tip 32. The suction holes 36 are entirely positioned within the IVC. Additionally, a plurality of atrial suction holes 38 are grouped together in a short segment of the cannula 20 that is positioned within the RA. In one embodiment, there are eight such suction holes 38 positioned in atrium.
• a distal reinforcement segment 40 In between the segment of the cannula 20 having the atrial suction holes 38, and the segment having the distal suction holes 36, is a distal reinforcement segment 40. Furthermore, a proximal reinforcement segment 42 begins just proximal to the atrial suction holes 38 and extends almost to the proximal end 30.
• the body of the cannula 20 is made of relatively soft polymer material, and the reinforcements 40 and 42 may be provided by a helically coiled wire, preferably stainless steel, molded within the wall of the cannula.
• a connector portion 44 on a proximal end of the cannula provides a coupling to a venous return line extending to a venous reservoir (not shown).
• the venous drainage cannula 20 is shown in operation during a vacuum- assisted procedure.
• the right side of the cannula 20 in the region of the distal suction holes 36 is shown in contact with the wall of the IVC at 46.
• the left side of the cannula 20 in the region of the atrial suction holes 38 is shown in contact with the wall of the RA at 48.
• the suction created by the negative pressure within the cannula 20 tends to draw the soft tissue adjacent the suction holes 36, 38 against the cannula body so that the holes are occluded. Although some of these suction holes 36, 38 remain unoccluded, the reduction in flow capacity may be detrimental to the procedure.
• the increase in pressure drop by the occlusion of a number of the suction holes 36, 38 may impact the flow rate.
• the occlusion of a number of either the distal suction holes 36 or atrial suction holes 38 may preclude drainage from one of the right atrium or vena cava.
• An alternative technique for introducing the venous drainage cannula 20 is to enter through the IVC and extend the distal tip 32 upward into the SVC. The same problems of occlusion of the suction holes 36, 38 tend to occur, except that the distal suction holes 36 are occluded by the wall of the SVC.
• the occlusion of the suction holes during vacuum-assisted surgeries is more of a problem when heart is substantially manipulated.
• the heart may need to be shifted around by the surgeon to gain access to otherwise hard to reach locations.
• repair or replacement of the mitral or aortic valve, or repair or bypass of the circumflex artery around the backside of heart requires the surgeon to move the heart muscle around in order to deliver instruments and/or implants to the operating site.
• This manipulation of the heart may cause mis-alignment between the SVC, RA, and IVC.
• Mis-alignment means the cannula 20 traverses a severely curved or bent path within the RA and respective vena cava, and inevitably brings the suction holes into close proximity with the surrounding soft tissue.
• the present invention comprises a kink-resistant venous return cannula having enhanced drainage for vacuum-assisted minimally invasive surgery.
• the cannula includes an elongate, flexible tubular body having a proximal end and a distal tip.
• a distal drainage segment adjacent the distal tip has at least one drainage hole through the tubular body and a first axial length.
• a first reinforced or otherwise strengthened segment is located proximal to the distal drainage segment and has a second axial length.
• a first atrial suction segment with a plurality of drainage holes therein is located proximal to the first reinforced segment and has a third axial length.
• a second reinforced segment is located proximal to the first atrial suction segment and has a fourth axial length.
• a second atrial suction segment with a plurality of drainage holes therein is located proximal to the second reinforced segment and has a fifth axial length.
• a proximal reinforced segment is located proximal to the second atrial suction segment and may extend substantially along the rest of the cannula into proximity with the proximal end.
• the present invention provides a venous cannula, comprising an elongate tubular body having a proximal end and a distal tip.
• Three discrete suction segments are formed in the tubular body each having a plurality of drainage holes therein.
• at least two of the segments are located closer to the distal tip than to the proximal end of the tubular body.
• the lengths of the two reinforced segments relative to lengths of said discrete suction segments and the number and size of the drainage holes are sufficient to avoid kinking of the cannula.
• Each of the reinforced segments has an axial length that is preferably equal or longer than each of two of the suction segments.
• an insertion indicator line is provided on the tubular body proximal to the proximally-most located suction segment, wherein an insertion length is defined between the distal tip and the indicator line.
• the three suction segments desirably comprise a distal segment adjacent the distal tip and first and second atrial suction segments located in series proximally with respect to the distal segment.
• the first atrial suction segment desirably commences at a point that is about 30-50% (preferably between 38-46%) of the insertion length from the distal tip.
• the second atrial suction segment may be spaced from the first atrial suction segment a distance between about 10-20% (preferably between 14- 17%) of the insertion length.
• Figure 1 is a perspective cutaway view of the heart of a patient showing a venous return cannula of the prior art positioned for venous drainage within the right atrium and inferior vena cava;
• Figure 2 is a perspective cutaway view of the heart of a patient showing an exemplary venous return cannula of the present invention positioned for venous drainage within the right atrium and inferior vena cava and illustrating the enhanced drainage capabilities of the cannula;
• Figure 3 is a perspective cutaway view of the heart of a patient showing an exemplary venous return cannula of the present invention positioned for venous drainage within the right atrium and inferior vena cava and further illustrating the enhanced drainage capabilities of the cannula;
• Figure 4A is a plan view of one embodiment of a venous return cannula of the present invention.
• Figure 4B is an elevational view of the venous return cannula of Figure 4A.
• Figures 2 and 3 illustrate a cannula 50 of the present invention positioned within the right atrium (RA) and inferior vena cava (IVC).
• the cannula 50 is shown in more detail in Figures 4A and 4B and includes a tubular cannula body that extends from a proximal end 52 to a tapered distal tip 54 having a distal aperture 56.
• the cannula 50 of the present invention includes two discrete segments 58a and 58b having atrial suction holes 60a and 60b in addition to the distal segment 62 having distal suction aperture 56, and preferably a plurality of distal suction holes 64.
• a first reinforcement segment 66 extends between the distal segment 62 and the first atrial suction segment 58a
• a second reinforcement segment 68 extends between the first and second atrial suction segments 58a, 58b
• a proximal, elongated reinforcement segment 70 may extend from the second atrial suction segment 58b at least and up to a proximal connector portion 72.
• the first reinforcement segment 66 extends at least up to the end of the length of the cannula that is inserted in the body vessel, however, it may extend substantially along the rest of the cannula into proximity with its proximal end.
• the three reinforcement segments 66, 68, 70 are dimensioned such that two of them are preferably longer than the two suction segments 58a, 58b.
• the reinforcement segments 66, 68, and 70 are desirably formed by molding a helically coiled stainless steel wire in the body of the cannula 50.
• Other means for reinforcing or strengthening the cannula body between the segments having suction holes are possible, including, but not limited to, segments with thicker walls, different materials, molded ribs, attached ribs, embedded fibers, mat or rings, or other suitable expedients.
• the cannula 50 further includes one or more indicator lines for gauging the depth of insertion of the cannula.
• the cannula 50 may include a single proximal indicator line 80 spaced proximally from the second atrial suction segment 58b. Additionally, a pair of distal indicator lines 82 are spaced proximally from the indicator line 80.
• Figures 2 and 3 illustrate the cannula 50 inserted through an aperture 90 formed in the right atrial appendage (RAA) and secured therein using purse string sutures 92.
• the cannula 50 is inserted into the right atrium (RA) so that the distal segment 62 having the distal suction holes 64 is located within the inferior vena cava (IVC).
• IVC inferior vena cava
• Both the first and second proximal suction segments 58a and 58b are located within the RA.
• This positioning of the cannula is insured by the surgeon by advancing the cannula until the aperture 90 is between the distal indicator line 80 and the proximal indicator lines 82.
• the axial spacing of the distal tip and suction holes of the cannula 50 relative to the indicator lines 80, 82 is designed to position the cannula in most adult patients as illustrated in Figure 2.
• a different relative axial spacing can be used.
• the surgeon can select from an array of sizes or cannulas 50 with different relative axial spacing, all of which are generally proportional to the spacing shown and described herein.
• Figure 2 shows the first suction segment 58a against the left wall of the RAA, such as might occur when a vacuum is drawn through the cannula 50 and the heart is manipulated, thus occluding some of the suction holes 60a.
• the second suction segment 58b is shown distanced from the su ⁇ ounding tissue walls so that all of the suction holes 60b are open and available for draining blood.
• the first suction segment 58a is shown in the middle of the RA, and not in contact with the su ⁇ ounding tissue walls so that all of the suction holes 60a are open.
• the second suction segment 58b is shown in contact with the left wall of the RA so that some of the suction holes 60b are occluded.
• both of the suction segments 58a and 58b may be out of contact with the su ⁇ ounding tissue walls so that all of the suction holes 60a, 60b remain open.
• the illustrations in Figures 2 and 3 are believed to represent the worst-case scenario with the cannula 50 of the present invention. This performance has been verified by numerous clinical trials.
• the lengths of the respective suction and reinforcement segments are preferably as seen in the exemplary embodiment of Figures 4A and 4B. It should be emphasized, however, that these dimensions and/or proportions are exemplary only, and should not limit the claims.
• the cannula 50 of the present invention better hole distribution and less chance of occlusion than the prior art without creating a structure that would be prone to kinking. That is, there is a balance between improved suction performance and kink-resistance provided by exemplary embodiments of the present invention.
• the distal suction segment 62 desirably extends from the distal tip 54 a distance A of about 1.75 inches.
• the first reinforcement segment 66 extends an axial distance B of about 1.25 inches.
• the first and second atrial suction segments 58a and 58b may extend similar distances C and C of about 1.15 inches.
• the second reinforcement segment 68 has an axial length D of about 1.15 inches.
• the distance E between the second atrial suction segment 58b and proximal indicator line 80 is about 1.18 inches.
• the distance F from the distal tip 54 to the proximal indicator line 80 is about 6.53 inches, while the distance G from the distal tip 54 to the distal indicator lines 82 is about 8.0 inches.
• the distance B between the distal suction segment 62 and the first atrial suction segment 58a is less than, and preferably about 70% of, the length A of the distal suction segment.
• the lengths C and C of both the first and second atrial suction segments 58a, 58b may be different, but are preferably equal, and are both less than length A (and preferably less than about 50% of length A).
• the spacing D between the first and second atrial suction segments 58a, 58b is desirably less than distance B, and preferably about 92 percent of distance B.
• the distance from the second atrial suction segment 58b to the proximal indicator line 80 is desirably about the same as spacing D, and more preferably slightly greater than spacing D.
• the length F from the distal tip 54 to the proximal indicator line 80 is the minimum extent of the cannula 50 inserted into the heart, and the length G is the maximum extent of the cannula inserted in the heart.
• the distal segment 62 makes up between 20- 30% (preferably between 22-27%)
• the first reinforcement portion 66 makes up between 15-20% (preferably between 16-19%)
• the first and second atrial suction segments 58a, 58b each make up between 5-10% (preferably between 7-9%)
• the second reinforcement portion 68 makes up between 15-20% (preferably between 14-17%).
• first atrial suction segment 58a preferably commences at a point about 30-50% (more preferably about 38-46%) along the length of the inserted portion (length range F to G) from the distal tip 54
• second atrial suction segment 58b preferably commences at a point about 55-75% (more preferably about 59-73%) along the inserted portion from the distal tip 54
• the discrete first and second atrial suction segments 58a and 58b are desirably spaced apart between about 10-20% (more preferably about 14-18%) of the length of the inserted portion (length range F to G) of the cannula 50, or between about 0.9 and 2.0 inches.
• the aforementioned dimensional relationships provide an optimum spacing between the discrete segments of suction holes, while also providing rigidity to the cannula 50 to prevent kinking. That is, between each of the segments having suction holes the cannula 50 is reinforced with, for example, a helically wound wire. Although more segments having suction holes may be provided, there is an attendant increased tendency of the cannula body to kink in the un-reinforced suction segments. Therefore, the aforementioned placement and length of suction segments is believed to provide an optimum compromise between adequate drainage and strength.
• the particular number and size of the various suction holes is also significant to ensure adequate drainage through the cannula 50.
• the hole size, spacing, and configuration may depend on the cannula bore, which in the exemplary embodiment is about 0.38 inches.
• more suction holes 64 are provided in the distal suction segment 62, than in either of the first or second atrial suction segments 58a or 58b.
• the circular holes preferably have a diameter of about 0.15 inches, and oval-shaped holes have a minor dimension of 0.13 inches and a major dimension of 0.38 inches.
• the holes are distributed circumferentially around the tubular body to minimize the proportion of holes occluded at any one time.
• suction holes 60a, 60b there are six suction holes 60a, 60b for each of the atrial suction segments 58a and 58b.
• the suction holes 60a, 60b preferably have a diameter of about 0.15 inches.
• more or less holes may be provided in any of the suction segments, and the size of each may be modified according to the drainage requirements.
• enough holes of sufficient size must be provided in each of the suction segments to accommodate adequate venous flow in case one or the other of the suction segments is in contact with tissue so that some of the suction holes are occluded.
• the present invention contemplates several ways to quantify this balance between an increased number of holes/segments and a sufficient strength. For example, the number of holes per inch of cannula could be used. Alternatively, the number of holes per suction segment, and the maximum number of segments could be specified. Or, the total area of the suction holes in relation to the cannula length affected could be set.
• a chart of flow rates against different suction pressures could be provided and optimized with the bending strength of the cannula.
• Those of skill in the art will therefore recognize that there are a number of ways to determine the practical maximum number of suction holes that can be effectively used, and the present invention is intended to cover the various formulations.
• a cannula as described herein having the particular diameter, suction hole size, segment size and placement, and reinforcement segment size and placement may have more than the six (6) suction holes per suction segment as illustrated.
• One example is to provide eight (8) suction holes per suction segment, assuming all other parameters remain the same.
• the number of holes per inch of cannula, the number of holes per segment using only two segments, and the total area of the suction holes relative to the affected cannula length can be calculated from the exemplary specifications given above.
• the actual flow rates at different suction pressures could be determined using conventional measurement techniques and co ⁇ elated with cannulas of different bending strengths. Therefore, those of skill in the art will realize that the flow rate can be maximized for any particular cannula while retaining kink-resistance within predetermined bending stress limits, which limits can be empirically determined with strain gauges and the like in the surgical field, or in training mock-ups of the heart.

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• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Heart & Thoracic Surgery (AREA)
• Engineering & Computer Science (AREA)
• General Health & Medical Sciences (AREA)
• Anesthesiology (AREA)
• Biomedical Technology (AREA)
• Hematology (AREA)
• Veterinary Medicine (AREA)
• Animal Behavior & Ethology (AREA)
• Public Health (AREA)
• Vascular Medicine (AREA)
• Biophysics (AREA)
• Pulmonology (AREA)
• Cardiology (AREA)
• External Artificial Organs (AREA)
• Media Introduction/Drainage Providing Device (AREA)

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• 2000
  • 2000-11-07 WO PCT/US2000/030686 patent/WO2001034237A1/en active Search and Examination
  • 2000-11-07 EP EP00978424A patent/EP1251898A1/de not_active Withdrawn
  • 2000-11-07 AU AU15890/01A patent/AU784413B2/en not_active Expired
  • 2000-11-07 CA CA002391214A patent/CA2391214C/en not_active Expired - Lifetime
  • 2000-11-07 JP JP2001536232A patent/JP2003534828A/ja active Pending
• 2009
  • 2009-03-05 JP JP2009052678A patent/JP2009148602A/ja active Pending

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