Patent Description:
The present invention relates, in general, to devices and methods for assisting a patient's heart and/or lungs, with a cannula, a pump, and a gas exchange device. More specifically, the present invention relates to devices and methods for providing the patient with blood flow, oxygenation, and carbon dioxide removal, all while unloading the left side of the patient's heart with one cannula configured for draining blood flow from two sites within the patient's vasculature and a second cannula for returning blood into the patient's vasculature after gas exchange, with a pump and gas exchange device provided outside the patient's body.

Traditional veno-arterial extracorporeal membrane oxygenation (VA ECMO) is the current standard of care used for treating right ventricular failure and respiratory failure percutaneously. A VA ECMO procedure draws blood from the right atrium and pumps it through an oxygenator and back into the arterial circulation via the femoral artery. VA ECMO bypasses the lungs and the heart completely, elevating arterial pressure and infusing blood into the arterial system with added oxygen and reduced carbon dioxide. One of the results of this therapy is that the blood that remains in the heart must be pumped by the heart to a higher pressure level in order to be ejected by the left ventricle because the VA ECMO system has elevated the arterial pressure to a higher level that represents a higher afterload to the pumping effort of the left ventricle.

In traditional VA ECMO systems, one cannula is placed in the right atrium to drain blood therefrom and a separate, second cannula is placed in an artery to return oxygenated (and cleansed from carbon dioxide) blood at a higher pressure. Some blood inevitably flows past the right atrium drainage cannula, and once the blood gets into the right ventricle, the heart's valves prevent this blood from being drained into the VA ECMO system. Instead, the blood flows into the left ventricle, which must pump this blood to the higher pressure of the arterial system. This causes an additional load on the heart. In patients with a severely weakened heart muscle, the left ventricle cannot pump the blood to the higher pressure of the arterial system, causing the left ventricle to be distended and requiring emergent action. Even in patients whose left ventricle is capable of pumping blood therefrom, fluid can build up in the patient's lungs. In both cases, surgery is generally required to (a) insert a second drainage cannula into the pulmonary artery, (b) implant a pump to operate along with the ECMO circuit; or (c) insert a transseptal cannula into the left atrium.

One of the major deficiencies of traditional VA ECMO systems and methods is that they do not sufficiently unload the heart and reduce the workload on the strained muscle. In one existing VA ECMO system, one drainage cannula is configured to draw blood from the right atrium, while a separate, second cannula is configured to draw blood from the pulmonary artry. The pulmonary artery cannula drains blood flowing past the right atrial drainage cannula, and it may also drain residual blood in the left atrium, thereby reducing left atrial pressure and thus preventing additional load on the heart, or resulting in VA ECMO with an unloaded left ventricle. Blood is drawn from both cannulae, pumped through an oxygenator and delivered back into the arterial circulation via a separate, third cannula into the femoral artery or the subclavian artery.

There are a number of disadvantages associated with traditional VA ECMO systems and the methods. Traditional cannulas used in VA ECMO procedures have a single lumen and are inserted at multiple insertion sites. Multiple insertion sites increase the risk of bleeding, vessel damage, and infection, as well as pain and discomfort to the patient. Moreover, these cannulas are designed and built for short-term acute therapies. While multi-lumen cannulas exist in the art, such cannulas are generally not configured for draining blood flow from two separate sites. For example, a dual lumen cannula, such as the dual lumen cannula described in <CIT>, can be used to unload the right side of the heart by drawing blood from the right atrium through one lumen and infusing blood to the pulmonary artery through a second lumen. For example, a dual lumen endovascular cardiac venting catheter is disclosed in <CIT>.

In view of the foregoing, there is a need for a VA ECMO system and method having a multi-lumen drainage cannula with a single insertion point. There is an additional need for a VA ECMO system and method having a multi-lumen drainage cannula that eliminates multiple access sites and reduces bleeding, vessel damage, and infection, as well as pain and discomfort to the patient. Furthermore, there exists a need for a VA ECMO system and method having a multi-lumen drainage cannula that enables patients to be ambulatory with access sites provided in the neck or groin area.

According to one aspect of the present disclosure, a VA ECMO system may include a dual lumen drainage cannula having a first drainage tube with a proximal end, a distal end, and a sidewall extending between the proximal end and the distal end. The dual lumen cannula may further have a second drainage tube coaxially aligned with the first drainage tube with a proximal end, a distal end, and a sidewall extending between the proximal end and the distal end. A connector may be configured for fluidly connecting with the first drainage tube and the second drainage tube. The VA ECMO system may further have a blood pump with a pump inlet and a pump outlet. The pump outlet may be configured for fluidly connecting to the connector. The VA ECMO system may further have an oxygenator having an oxygenator inlet and an oxygenator outlet. The oxygenator inlet may be configured for fluidly connecting with the pump outlet; and an infusion cannula configured for fluidly connecting with the oxygenator outlet.

According to another aspect of the present disclosure, the first drainage tube may have at least one first drainage aperture provided at the distal end. The second drainage tube may have at least one second drainage aperture provided at the distal end. The at least one first drainage aperture may extend through the sidewall of the first drainage tube. The at least one second drainage aperture may extend through the sidewall of the second drainage tube. The at least one first drainage aperture may extend through the sidewall of the first drainage tube in a direction perpendicular to a longitudinal axis of the first drainage tube. The at least one second drainage aperture may extend through the sidewall of the second drainage tube in a direction perpendicular to a longitudinal axis of the second drainage tube. The at least one first drainage aperture may extend through the sidewall of the first drainage tube at an acute or obtuse angle with respect to a longitudinal axis of the first drainage tube. The at least one second drainage aperture may extend through the sidewall of the second drainage tube at an acute or obtuse angle with respect to a longitudinal axis of the second drainage tube. A plurality of first drainage apertures may extend in a circular pattern around the first drainage tube. A plurality of second drainage apertures may extend in a circular pattern around the second drainage tube. The at least one first drainage aperture may be separated from the at least one second drainage aperture by a predetermined distance along a longitudinal axis of the first drainage tube. The predetermined distance may be selected based on at least one of patient age, patient size, and a desired flow rate. The dual lumen cannula may be adapted for maneuvering through the patient's vasculature such that the distal end of the first drainage tube is substantially within the patient's right atrium and such that the distal end of the second drainage tube is substantially within the patient's pulmonary artery. The pump may be a centrifugal pump, an axial pump, or a roller pump. a controller for controlling the operation of the pump.

According to another aspect of the present disclosure, a dual lumen drainage cannula may be configured for use in a VA ECMO system. The dual drainage cannula may have a first drainage tube configured for insertion into a right atrium of a patient and a second drainage tube configured for insertion into a pulmonary artery of a patient. The first drainage tube may have a body with a proximal end, a distal end, and a sidewall extending between the proximal end and the distal end with at least one first drainage aperture provided at the distal end. The at least one first drainage aperture may extend through the sidewall of the first drainage tube. The second drainage tube may be coaxially aligned with the first drainage tube and may have a proximal end, a distal end, and a sidewall extending between the proximal end and the distal end with at least one second drainage aperture provided at the distal end. The at least one second drainage aperture may extend through the sidewall of the second drainage tube. The dual lumen drainage cannula may have a connector configured for fluidly connecting with the first drainage tube and the second drainage tube. The at least one first drainage aperture may be separated from the at least one second drainage aperture by a predetermined distance along a longitudinal axis of the first drainage tube. The predetermined distance may be selected based on at least one of patient age, patient size, and a desired flow rate.

According to another aspect of the present disclosure, a method of providing VA ECMO of a heart may include providing a dual lumen drainage cannula having a first drainage tube with a body with a proximal end, a distal end, and a sidewall extending between the proximal end and the distal end with at least one first drainage aperture provided at the distal end. The at least one first drainage aperture may extend through the sidewall of the first drainage tube. The dual lumen drainage cannula may further have a second drainage tube coaxially aligned with the first drainage tube and may have a proximal end, a distal end, and a sidewall extending between the proximal end and the distal end with at least one second drainage aperture provided at the distal end. The at least one second drainage aperture may extend through the sidewall of the second drainage tube. The dual lumen drainage cannula may further have a connector configured for fluidly connecting with the first drainage tube and the second drainage tube. The method may further include inserting the dual lumen drainage cannula into a first site in a patient's vasculature, maneuvering the dual lumen drainage cannula through the patient's vasculature such that the first distal end of the first infusion tube is at least within proximity of the patient's right atrium and such that the second distal end of the second drainage tube is at least within proximity of the patient's pulmonary artery, withdrawing blood through the first and second drainage tubes using a blood pump, pumping withdrawn blood through an oxygenator to reduce carbon dioxide content of the blood, and delivering oxygenated blood with reduced carbon dioxide content to a second site in the patient's vasculature.

In accordance with other aspects of the present disclosure, the VA ECMO system and method may be characterized by one or more of the following clauses. The following clauses further reflect or emphasise aspects of the present disclosure that may be supplementary to or independent of the invention as claimed but which fall within the totality of the disclosed inventive contribution.

Clause <NUM>. A VA ECMO system comprising: a dual lumen drainage cannula comprising: a first drainage tube having a proximal end, a distal end, and a sidewall extending between the proximal end and the distal end; a second drainage tube coaxially aligned with the first drainage tube and having a proximal end, a distal end, and a sidewall extending between the proximal end and the distal end; and a connector configured for fluidly connecting with the first drainage tube and the second drainage tube; a blood pump having a pump inlet and a pump outlet, the pump outlet configured for fluidly connecting to the connector; an oxygenator having an oxygenator inlet and an oxygenator outlet, the oxygenator inlet configured for fluidly connecting with the pump outlet; and an infusion cannula configured for fluidly connecting with the oxygenator outlet.

Clause <NUM>. The VA ECMO system according to clause <NUM>, wherein the first drainage tube has at least one first drainage aperture provided at the distal end.

Clause <NUM>. The VA ECMO system according to clause <NUM> or <NUM>, wherein the second drainage tube has at least one second drainage aperture provided at the distal end.

Clause <NUM>. The VA ECMO system according to any of clauses <NUM>-<NUM>, wherein the at least one first drainage aperture extends through the sidewall of the first drainage tube.

Clause <NUM>. The VA ECMO system of according to any of clauses <NUM>-<NUM>, wherein the at least one second drainage aperture extends through the sidewall of the second drainage tube.

Clause <NUM>. The VA ECMO system according to any of clauses <NUM>-<NUM>, wherein the at least one first drainage aperture extends through the sidewall of the first drainage tube in a direction perpendicular to a longitudinal axis of the first drainage tube.

Clause <NUM>. The VA ECMO system according to any of clauses <NUM>-<NUM>, wherein the at least one second drainage aperture extends through the sidewall of the second drainage tube in a direction perpendicular to a longitudinal axis of the second drainage tube.

Clause <NUM>. The VA ECMO system according to any of clauses <NUM>-<NUM>, wherein the at least one first drainage aperture extends through the sidewall of the first drainage tube at an acute or obtuse angle with respect to a longitudinal axis of the first drainage tube.

Clause <NUM>. The VA ECMO system according to any of clauses <NUM>-<NUM>, wherein the at least one second drainage aperture extends through the sidewall of the second drainage tube at an acute or obtuse angle with respect to a longitudinal axis of the second drainage tube.

Clause <NUM>. The VA ECMO system according to any of clauses <NUM>-<NUM>, wherein a plurality of first drainage apertures extends in a circular pattern around the first drainage tube.

Clause <NUM>. The VA ECMO system according to any of clauses <NUM>-<NUM>, wherein a plurality of second drainage apertures extends in a circular pattern around the second drainage tube.

Clause <NUM>. The VA ECMO system according to any of clauses <NUM>-<NUM>, wherein the at least one first drainage aperture is separated from the at least one second drainage aperture by a predetermined distance along a longitudinal axis of the first drainage tube.

Clause <NUM>. The VA ECMO system according to clause <NUM>, wherein the predetermined distance is selected based on at least one of patient age, patient size, and a desired flow rate.

Clause <NUM>. The VA ECMO system according to any of clauses <NUM>-<NUM>, wherein the dual lumen cannula is adapted for maneuvering through the patient's vasculature such that the distal end of the first drainage tube is substantially within the patient's right atrium and such that the distal end of the second drainage tube is substantially within the patient's pulmonary artery.

Clause <NUM>. The VA ECMO system according to any of clauses <NUM>-<NUM>, wherein the pump is a centrifugal pump, an axial pump, or a roller pump.

Clause <NUM>. The VA ECMO system according to any of clauses <NUM>-<NUM>, further comprising a controller for controlling the operation of the pump.

Clause <NUM>. A dual lumen drainage cannula configured for use in a VA ECMO system, the dual drainage cannula comprising: a first drainage tube configured for insertion into a right atrium of a patient, the first drainage tube having a body with a proximal end, a distal end, and a sidewall extending between the proximal end and the distal end with at least one first drainage aperture provided at the distal end, the at least one first drainage aperture extending through the sidewall of the first drainage tube; a second drainage tube configured for insertion into a pulmonary artery of a patient, the second drainage tube coaxially aligned with the first drainage tube and having a proximal end, a distal end, and a sidewall extending between the proximal end and the distal end with at least one second drainage aperture provided at the distal end, the at least one second drainage aperture extending through the sidewall of the second drainage tube; and a connector configured for fluidly connecting with the first drainage tube and the second drainage tube.

Clause <NUM>. The VA ECMO system of clause <NUM>, wherein the at least one first drainage aperture is separated from the at least one second drainage aperture by a predetermined distance along a longitudinal axis of the first drainage tube.

Clause <NUM>. The VA ECMO system of clause <NUM>, wherein the predetermined distance is selected based on at least one of patient age, patient size, and a desired flow rate.

Clause <NUM>. A method of providing VA ECMO of a heart, the method comprising: providing a dual lumen drainage cannula comprising: a first drainage tube having a body with a proximal end, a distal end, and a sidewall extending between the proximal end and the distal end with at least one first drainage aperture provided at the distal end, the at least one first drainage aperture extending through the sidewall of the first drainage tube; a second drainage tube coaxially aligned with the first drainage tube and having a proximal end, a distal end, and a sidewall extending between the proximal end and the distal end with at least one second drainage aperture provided at the distal end, the at least one second drainage aperture extending through the sidewall of the second drainage tube; and a connector configured for fluidly connecting with the first drainage tube and the second drainage tube; inserting the dual lumen drainage cannula into a first site in a patient's vasculature; maneuvering the dual lumen drainage cannula through the patient's vasculature such that the first distal end of the first infusion tube is at least within proximity of the patient's right atrium and such that the second distal end of the second drainage tube is at least within proximity of the patient's pulmonary artery; withdrawing blood through the first and second drainage tubes using a blood pump; pumping withdrawn blood through an oxygenator to reduce carbon dioxide content of the blood; and delivering oxygenated blood with reduced carbon dioxide content to a second site in the patient's vasculature.

These and other features and characteristics of the VA ECMO system having a multi-lumen drainage cannula, as well as the methods of operation and functions of the related elements of structures and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only. As used in the specification and the claims, the singular form of "a", "an", and "the" include plural referents unless the context clearly dictates otherwise.

For purposes of the description hereinafter, the terms "upper", "lower", "right", "left", "vertical", "horizontal", "top", "bottom", "lateral", "longitudinal", and derivatives thereof shall relate to the disclosure as it is oriented in the drawing figures. When used in relation to the syringe, the term "proximal" refers to the portion of a cannula closer to a medical practitioner handling a cannula. The term "distal" refers to a portion of a cannula farther from a medical practitioner handling ae cannula. It is to be understood, however, that the disclosure may assume alternative variations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary aspects of the disclosure. Hence, specific dimensions and other physical characteristics related to the aspects disclosed herein are not to be considered as limiting.

Referring to the drawings, in which like reference characters refer to like parts throughout the several views thereof, various aspects of a VA ECMO system and method will be discussed with reference to <FIG>. In various aspects, the VA ECMO system and method discussed herein utilize a multi-lumen drainage cannula. In some non-limiting aspects, a coaxial, dual lumen drainage cannula <NUM> (hereinafter referred to as "drainage cannula <NUM>") is shown. With initial reference to <FIG>, an assembled drainage cannula <NUM>, according to one aspect, generally includes a first drainage tube <NUM> having a first length and a second drainage tube <NUM> having a second length. In some aspects, the first length of the first drainage tube <NUM> is greater than the second length of the second drainage tube <NUM>.

The first drainage tube <NUM> is disposed within the second drainage tube <NUM> in a coaxial arrangement centered about a central axis <NUM>. In other aspects, the first and second drainage tubes <NUM>, <NUM> may be arranged in a side-by-side arrangement with an axial alignment of the tubes <NUM>, <NUM> along the length thereof. Each of the first drainage tube <NUM> and the second drainage tube <NUM> has a first circumference defining a first lumen and a second circumference defining a second lumen, respectively. The first circumference of the first drainage tube <NUM> is smaller than the second circumference of the second drainage tube <NUM> such that the first drainage tube <NUM> may be placed within the second lumen of the second drainage tube <NUM>. One or both of the first drainage tube <NUM> and the second drainage tube <NUM> may be manufactured from a medical-grade material, such as polyurethane. Alternatively, one or both of the first drainage tube <NUM> and the second drainage tube <NUM> may be made from PVC or silicone, and may be dip molded, extruded, co-molded, or made using any other suitable manufacturing technique.

The drainage cannula <NUM> has sufficient placement flexibility adapted for placement of the drainage cannula <NUM> within a patient's body. The drainage cannula <NUM> may be used with an introducer (not shown) to guide the drainage cannula <NUM> as it is inserted within the patient's body.

Desirably, a vascular insertion site is provided at the internal jugular vein on the patient's neck area or the femoral vein on the patient's groin area. The drainage cannula <NUM> is adapted for placement above or below the right atrium of the patient's heart with an access to the patient's pulmonary artery. With continuing reference to <FIG>, the drainage cannula <NUM> is configured to withdraw blood directly from the patient's heart. Withdrawn blood is returned back into the patient's heart via an infusion cannula after oxygenating the blood within an oxygenator, as described herein. In some aspects, the first drainage tube <NUM> is configured for positioning within the patient's pulmonary artery to draw blood therefrom, while the second drainage tube <NUM> is configured for positioning within the patient's right atrium to draw blood therefrom.

A plurality of first drainage apertures <NUM> is provided at a distal end of the first drainage tube <NUM>. In one aspect, the plurality of first drainage apertures <NUM> may be arranged in a circular pattern extending around an outer circumference of the first drainage tube <NUM>. In some aspects, the plurality of first drainage apertures <NUM> may be disposed in multiple groups provided at various sites along an axial length of the first drainage tube <NUM>. Similarly, the second drainage tube <NUM> includes a plurality of second drainage apertures <NUM> provided at a distal end of the second drainage tube <NUM>. In one aspect, the plurality of second drainage apertures <NUM> may be arranged in a circular pattern extending around an outer circumference of the second drainage tube <NUM>. In other aspects, the plurality of second drainage apertures <NUM> may be arranged in groups disposed at various sites along an axial length of the second drainage tube <NUM>. The first drainage apertures <NUM> are separated from the second drainage apertures <NUM> by a distance D in an axial direction along the length of the drainage cannula <NUM>. In different aspects of the drainage cannula <NUM>, the axial separation of the first drainage apertures <NUM> from the second drainage apertures <NUM> is based on a distance between the pulmonary artery and the right atrium of the patient. This distance may vary based on the age and size of the patient. For example, a drainage cannula <NUM> having a specific overall length and diameter, along with a desired pattern and distance between the first drainage apertures <NUM> and the second drainage apertures <NUM> may be selected based on age and/or size of the patient.

With continuing reference to <FIG>, a connector <NUM> is provided at the proximal end of the drainage cannula <NUM>. The connector <NUM> includes a first outlet portion <NUM> in fluid communication with the first drainage tube <NUM> to transfer blood from the first drainage tube <NUM> to a blood pump in the direction of the arrow shown in <FIG>, as described herein. The first outlet portion <NUM> of the connector <NUM> is also in fluid communication with the second drainage tube <NUM> to transfer blood from the second drainage tube <NUM> to the blood pump in the direction of the arrow shown in <FIG>, as described herein. The first outlet portion <NUM> is in fluid communication with the first and second outlet portions <NUM>, <NUM> which are arranged such that the fluid pathways leading from the first and second drainage tubes <NUM>, <NUM> transition from a coaxial arrangement at a distal end of the connector <NUM> to an axially-offset arrangement at a proximal end of the connector <NUM>. Connector <NUM> restricts blood flow path to a streamlined consistent path to avoid hemolysis and stagnation in flow. In some aspects, the first and second outlet portions <NUM>, <NUM> may have barbed fittings for connecting to additional tubing that leads to the blood pump (shown in <FIG>).

With reference to <FIG>, and with continuing reference to <FIG>, the first drainage tube <NUM> is illustrated separate from the drainage cannula <NUM>. The first drainage tube <NUM> has a first elongate body <NUM> having a substantially cylindrical shape and extending from a first proximal end <NUM> to a first distal end <NUM> of the first drainage tube <NUM>. The first elongate body <NUM> includes a first lumen <NUM> extending throughout the entire length of the first drainage tube <NUM>. The first proximal end <NUM> includes a first connector portion <NUM> for coupling the first drainage tube <NUM> to the first outlet portion <NUM> of the connector <NUM> (shown in <FIG>). The first elongate body <NUM> of the first drainage tube <NUM> has a hollow structure defined by a first sidewall <NUM> extending circumferentially about the first elongate body <NUM>. The first sidewall <NUM> has a substantially constant thickness throughout the length of the first elongate body <NUM>, with a first tapering section <NUM> at the first distal end <NUM> of the first elongate body <NUM>. At the first proximal end <NUM> of the first elongate body <NUM>, the first sidewall <NUM> gradually increases in thickness before transitioning into the first connector portion <NUM>, which is done with a streamlined blood flow path to avoid hemolysis or flow stagnation. The first tapering section <NUM> located at the first distal end <NUM> has a thinner first sidewall <NUM> but retains the internal diameter of the first drainage tube <NUM>. The first tapering section <NUM> enables easier insertion of the first drainage tube <NUM> into the patient's body.

With specific reference to <FIG>, the first distal end <NUM> of the first drainage tube <NUM> is shown. The plurality of first drainage apertures <NUM> is provided at the first distal end <NUM> of the first drainage tube <NUM>. The plurality of first drainage apertures <NUM> extends circumferentially around the first distal end <NUM>. Each first drainage aperture <NUM> has a diameter of, for example, about <NUM> +/-<NUM> in. (<NUM> inch = <NUM>).

The plurality of first drainage apertures <NUM> may be arranged in an alternating pattern of axially offset rows of first drainage apertures <NUM> arranged around the circumference of the first drainage tube <NUM>. Each of the plurality of first drainage apertures <NUM> extends through the thickness of the first sidewall <NUM>. In one aspect, six first drainage apertures <NUM> may be provided on the first drainage tube <NUM>. The first drainage apertures <NUM> illustrated in <FIG> extend through the first sidewall <NUM> in a direction perpendicular to a longitudinal axis of the first elongate body <NUM>. Alternatively, the plurality of first drainage apertures <NUM> may extend through the thickness of the first sidewall <NUM> in an angled manner with respect to the longitudinal axis of the first elongate body <NUM>. For example, the plurality of first drainage apertures <NUM> may be arranged at an acute or obtuse angle with respect to a cross-sectional plane of the first drainage tube <NUM> and extend perpendicular to the longitudinal axis of the first elongate body <NUM>. In one aspect, one or more sensors (not shown) may be provided at the first distal end <NUM> of the first drainage tube <NUM>. The sensor(s) may be adapted for measuring, for example, local blood pressure and/or oxygen concentration. At least a portion of the first drainage tube <NUM> may be reinforced, such as with a wire at least partially embedded with the first drainage tube <NUM>. In addition, at least a portion of the first drainage tube <NUM> may have one or more indicia, such as a radiopaque marker, visible under fluoroscopy or cineangiography to assist with positioning of the first drainage tube <NUM> within the patient's vasculature.

The total cross-sectional area of the plurality of first drainage apertures <NUM> is desirably approximately equal to or greater than the cross-sectional area of the first lumen <NUM>. If the cross-sectional area of the plurality of first drainage apertures <NUM> is less than the cross-sectional area of the first lumen <NUM>, an undesirable pressure drop may occur. This pressure drop reduces the flow throughput within the first lumen <NUM> and impairs the efficiency of the first drainage tube <NUM>. Desirably, the total cross-sectional area of the plurality of first drainage apertures <NUM> exceeds the cross-sectional area of the first lumen <NUM> such that if one or more of the first drainage apertures <NUM> becomes clogged, the total cross-sectional area of the remaining first drainage apertures <NUM> is equal to or greater than the cross-sectional area of the first lumen <NUM>. In this manner, the blood flow through the first lumen <NUM> is maximized even if one or more of the first drainage apertures <NUM> become clogged. The first drainage tube <NUM> is configured for placement within the patient's vasculature such that the plurality of first drainage apertures <NUM> provided at the first distal end <NUM> of the first drainage tube <NUM> are positioned within the right atrium of the patient's heart.

With reference to <FIG>, and with continuing reference to <FIG>, the second drainage tube <NUM> is illustrated separate from the drainage cannula <NUM>. The second drainage tube <NUM> has a second elongate body <NUM> having a substantially cylindrical shape and extending from a second proximal end <NUM> to a second distal end <NUM> of the second drainage tube <NUM>. The second elongate body <NUM> includes a second lumen <NUM> extending throughout the entire length of the second drainage tube <NUM>. The second proximal end <NUM> includes a second connector portion <NUM> for coupling the second drainage tube <NUM> to the first outlet portion <NUM> of the connector <NUM> (shown in <FIG>). The second elongate body <NUM> of the second drainage tube <NUM> has a hollow structure defined by a second sidewall <NUM> extending circumferentially about the second elongate body <NUM>. The second sidewall <NUM> has a substantially constant thickness throughout the length of the second elongate body <NUM>, with a second tapering section <NUM> at the second distal end <NUM> of the second elongate body <NUM>. At the second proximal end <NUM> of the second elongate body <NUM>, the second sidewall <NUM> gradually increases in thickness before transitioning into the second connector portion <NUM>. The second tapering section <NUM> located at the second distal end <NUM> has a thinner second sidewall <NUM> but retains the internal diameter of the second lumen <NUM>. The second tapering section <NUM> enables easier insertion of the second drainage tube <NUM> into the patient's body.

With specific reference to <FIG>, the second distal end <NUM> of the second drainage tube <NUM> is shown. The plurality of second drainage apertures <NUM> is provided at the second distal end <NUM> of the second drainage tube <NUM>. The plurality of second drainage apertures <NUM> extends circumferentially around the second distal end <NUM>. Each second drainage aperture <NUM> has a diameter of, for example, about <NUM> in. +/- <NUM> in. (<NUM> inch = <NUM>).

The plurality of second drainage apertures <NUM> may be arranged in an alternating pattern of axially offset rows around the circumference of the second drainage tube <NUM>. Each of the plurality of second drainage apertures <NUM> extends through the thickness of the second sidewall <NUM>. In one aspect, eighteen second drainage apertures <NUM> are provided on the second drainage tube <NUM>. The second drainage apertures <NUM> illustrated in <FIG> extend through the second sidewall <NUM> in a direction perpendicular to a longitudinal axis of the second elongate body <NUM>. Alternatively, the plurality of second drainage apertures <NUM> may extend through the thickness of the second sidewall <NUM> in an angled manner with respect to the longitudinal axis of the second elongate body <NUM>. For example, the plurality of second drainage apertures <NUM> may be arranged at an acute or obtuse angle with respect to a cross-sectional plane of the second drainage tube <NUM> and extend perpendicular to the longitudinal axis of the second elongate body <NUM>. In one aspect, one or more sensors (not shown) may be provided at the second distal end <NUM> of the second drainage tube <NUM>. The sensor(s) may be adapted for measuring, for example, local blood pressure and/or oxygen concentration. At least a portion of the second drainage tube <NUM> may be reinforced, such as with a wire at least partially embedded with the second drainage tube <NUM>. In addition, at least a portion of the second drainage tube <NUM> may have one or more indicia, such as a radiopaque marker, visible under fluoroscopy or cineangiography to assist with positioning of the second drainage tube <NUM> within the patient's vasculature.

The total cross-sectional area of the plurality of second drainage apertures <NUM> is desirably approximately equal to or greater than the cross-sectional area of the second lumen <NUM>. If the cross-sectional area of the plurality of the second drainage apertures <NUM> is less than the cross-sectional area of the second lumen <NUM>, an undesirable pressure drop within the second drainage tube <NUM> may occur. This pressure drop reduces the flow throughput within the second lumen <NUM> and impairs the efficiency of the second drainage tube <NUM>. Desirably, the total cross-sectional area of the plurality of second drainage apertures <NUM> exceeds the cross-sectional area of the second lumen <NUM> such that if one or more second drainage apertures <NUM> becomes clogged, the total cross-sectional area of the remaining second drainage apertures <NUM> is equal to or greater than the cross-sectional area of the second lumen <NUM>. In this manner, the blood flow through the second lumen <NUM> is maximized even if one or more of the second drainage apertures <NUM> becomes clogged. The second drainage tube <NUM> is configured for placement within the patient's vasculature such that the plurality of second drainage apertures <NUM> provided at the second distal end <NUM> of the first drainage tube <NUM> are positioned within the pulmonary artery of the patient's heart.

With reference to <FIG>, the drainage cannula <NUM> shown in <FIG> is illustrated in cross-section. The second distal end <NUM> of the second drainage tube <NUM> is fixedly attached to the first drainage tube <NUM> along the length of the second tapering section <NUM>, as shown in <FIG>. The first drainage tube <NUM> and the second drainage tube <NUM> are coupled to the connector <NUM> in such a manner that the first drainage tube <NUM> and the second drainage tube <NUM> cross inside the connector <NUM> body without being connected to each other.

With reference to <FIG>, a VA ECMO system <NUM> having the drainage cannula <NUM> is illustrated in accordance with one aspect. The VA ECMO system <NUM> includes the drainage cannula <NUM> having the first drainage tube <NUM> configured for positioning within the right atrium <NUM> and the second drainage tube <NUM> configured for positioning within the patient's pulmonary artery <NUM>. The first and second drainage tubes <NUM>, <NUM> are positioned within the right atrium <NUM> and the pulmonary artery <NUM>, respectively, such that blood may enter the respective lumens <NUM>, <NUM> (shown in <FIG>) of the first and second drainage tubes <NUM>, <NUM> through the plurality of first and second drainage apertures <NUM>, <NUM>, respectively.

The connector <NUM> of the drainage cannula <NUM> may be connected to an inlet conduit <NUM> that delivers blood to an inlet <NUM> of a pump <NUM>. In some aspects, the connector <NUM> may be directly connected to the inlet <NUM> of the pump <NUM>. The pump <NUM> can be any centrifugal, axial, mixed, or roller pump that can produce adequate flowrates through the system. Several examples of pumps include, without limitation the TANDEMHEART pump manufactured by Cardiac Assist, Inc. , the BIOMEDICUS pump manufactured by Medtronic, Inc. , the ROTAFLOW pump manufactured by Jostra Medizintechnik AG, the CENTRIMAG pump manufactured by Levitronix, LLC, the SARNS DELPHIN pump manufactured by the Terumo Cardiovascular Group, the REVOLUTION pump manufactured by Cobe Cardiovascular, Inc, and others. The pump <NUM> can be secured to the patient, for instance with a holster <NUM> that holds the pump <NUM> with a strap or in a pocket. The holster <NUM> can be wrapped around the abdomen or shoulder or leg of the patient. A controller <NUM> may be provided for controlling the operation of the pump <NUM>. The controller <NUM> may be built into the pump <NUM>. The pump <NUM> further includes an outlet <NUM> for delivering blood to an oxygenator <NUM> at an oxygenator inlet <NUM>. The oxygenator <NUM> may be secured to the holster <NUM>. The pump outlet <NUM> may be directly connected to the oxygenator inlet <NUM>. In some aspects, the pump outlet <NUM> may be connected to the oxygenator inlet <NUM> via an outlet conduit <NUM>. With reference to <FIG>, the oxygenator <NUM> includes an oxygenation membrane <NUM> or other element(s) for oxygenating blood flowing from the oxygenator inlet <NUM> to an oxygenator outlet <NUM>. Oxygenated blood is delivered to an artery in the patient's body through an infusion cannula <NUM> (shown in <FIG>). While <FIG> illustrates the infusion cannula <NUM> connected to the patient's subclavian artery <NUM>, in other aspects, the infusion cannula <NUM> may be connected to the patient's femoral artery <NUM> (shown in <FIG>), or other artery of the patient's vascular system.

In accordance with some aspects, a single lumen cannula (not shown) having at least two axially offset drainage apertures may be used to draw blood from the right atrium and separately from the pulmonary artery, which, through minimal loss of pressure across the lung bed, will also drain the left atrium. At least one expandable balloon may be provided between the drainage apertures to prevent blood flow between the apertures.

Having described several non-limiting aspects of the drainage cannula <NUM> and the VA ECMO system <NUM>, an exemplary and non-limiting method for bilateral unloading of a patient's heart using the drainage cannula <NUM> will now be described with reference to <FIG>. Prior to the initial use, the package (not shown) containing the drainage cannula <NUM> is inspected for damage and expiration date. If undamaged and within the expiration date, the drainage cannula <NUM> is transferred to a sterile field using an aseptic technique.

In use, the drainage cannula <NUM> is inserted into the patient's vasculature in a percutaneous procedure prior to being connected to an ECMO system. Initially, a percutaneous entry needle (not shown) is used to access the patient's internal jugular vein <NUM> (<FIG>) or the femoral vein <NUM> (<FIG>). A guidewire, such as a guidewire having maximum diameter <NUM> in. (<NUM>) and a minimum length of <NUM>, is inserted into the vasculature. In some aspects, the positioning of the guidewire is verified using an appropriate imaging technique. In the next step, the patient's active clotting time is checked for approximately <NUM> seconds.

In the next step, the drainage cannula <NUM> is prepared for insertion into the patient's vasculature. The drainage cannula <NUM> is initially assembled by removing an introducer with a hemostasis cap from its protective sheath (not shown). After flushing the introducer with a saline solution to verify that the distal tip of the introducer is not obstructed, the introducer is inserted into the first drainage tube <NUM> until the hemostasis cap seats securely on the first connector portion <NUM>. The hemostasis cap is then secured to the second drainage tube <NUM>. In some aspects, first and second drainage tubes <NUM>, <NUM> may have indicia, such as the words "Distal" and "Proximal", respectively, to assist the medical practitioner in placing the introducer and the hemostasis cap into the correct drainage tube. The introducer/drainage cannula assembly may then be guided over the guidewire into the desired position within the patient's vasculature.

In particular, introducer/drainage cannula assembly is advanced over the guidewire until the assembly reaches the desired position. In some aspects, the introducer/drainage cannula assembly may be guided into a desired position using the indicia, such as a radiopaque marker located in the first distal end <NUM> of the first drainage tube <NUM>, that is visualized under fluoroscopy, transthoracic echocardiography, or cineangiography. The position of the introducer/drainage cannula assembly may be guided and verified by an imaging system described in <CIT>. In some aspects, the first drainage apertures <NUM> on the first drainage tube <NUM> may be placed in the right atrium, while the second drainage apertures <NUM> on the second drainage tube <NUM> may be placed within the pulmonary artery. After noting and recording the location of the drainage cannula <NUM>, the introducer can be removed, leaving the hemostasis cap on the drainage cannula <NUM> to minimize blood loss. The drainage cannula <NUM> can be clamped at a clamping zone indicated on first drainage tube <NUM> as the introducer is removed. The hemostasis cap can then be removed from the second drainage tube <NUM>.

To connect the drainage cannula <NUM> to the blood pump <NUM>, a wet-to-wet, or other type, of a connection is made between the drainage cannula <NUM> and tubing that is attached to the pump <NUM>. Both tubes of the drainage cannula <NUM> should be connected to the connector <NUM> and the inlet of the pump <NUM>, and the drainage cannula <NUM> should not be kinked. After verifying the correct positioning and insertion depth of the drainage cannula <NUM>, the drainage cannula <NUM> can be secured to the patient, such as by suturing with a suture wing. The patient's active clotting time is checked for approximately <NUM>-<NUM> seconds before turning on the blood pump <NUM> to circulate the patient's blood through the system. During use, the blood pump <NUM> pumps the blood withdrawn through the first and second drainage tubes <NUM>, <NUM> through the oxygenator <NUM> to oxygenate the blood, which is then returned to the patient via the infusion line <NUM>. After use, the pump <NUM> is turned off and the pump inlet and outlet are clamped. The tubing is cut and the pump <NUM> may be removed. Any sutures securing the drainage cannula <NUM> to the patient may be removed, and the drainage cannula <NUM> removed from the patient. The puncture site may then be treated and dressed.

Although the disclosure has been described in detail for the purpose of illustration based on what is currently considered to be the most practical and preferred aspects, it is to be understood that such detail is solely for that purpose and that the disclosure is not limited to the disclosed aspects, but, on the contrary, is intended to cover modifications and equivalent arrangements. For example, it is to be understood that the present disclosure contemplates that, to the extent possible, one or more features of any aspect can be combined with one or more features of any other aspect.

Claim 1:
A veno-arterial extracorporeal membrane oxygenation (VA ECMO) system(<NUM>) comprising:
a dual lumen drainage cannula (<NUM>) comprising:
a first drainage tube (<NUM>) having a proximal end (<NUM>), a distal end (<NUM>), and a sidewall (<NUM>) extending between the proximal end (<NUM>) and the distal end (<NUM>); and
a second drainage tube (<NUM>) in axial alignment with the first drainage tube (<NUM>) and having a proximal end (<NUM>), a distal end (<NUM>), and a sidewall (<NUM>) extending between the proximal end (<NUM>) and the distal end (<NUM>);
a connector (<NUM>) configured for connecting to a proximal end of the drainage cannula (<NUM>) such that fluid pathways leading from the first and second drainage tubes (<NUM>, <NUM>) transition from a coaxial arrangement at a distal end of the connector (<NUM>) to an axially-offset arrangement at a proximal end of the connector (<NUM>);
a blood pump (<NUM>) having a pump inlet (<NUM>) and a pump outlet (<NUM>), the pump inlet (<NUM>) configured for fluidly connecting to the first drainage tube (<NUM>) and the second drainage tube (<NUM>);
an oxygenator (<NUM>) having an oxygenator inlet (<NUM>) and an oxygenator outlet (<NUM>), the oxygenator inlet (<NUM>) configured for fluidly connecting with the pump outlet (<NUM>); and
an infusion cannula (<NUM>) configured for fluidly connecting with the oxygenator outlet (<NUM>),
wherein the distal end (<NUM>) of the first drainage tube (<NUM>) has a plurality of first drainage apertures (<NUM>) and the distal end (<NUM>) of the second drainage tube (<NUM>) has a plurality of second drainage apertures (<NUM>),
wherein the first drainage tube (<NUM>) and the second drainage tube (<NUM>) are fixedly connected to each other at the distal end (<NUM>) of the second drainage tube (<NUM>).