(i9) United States
`(i2) Patent Application Publication
`Atkinson et al.
`
`US 20140025143A1
`
`(io) Pub. No.: US 2014/0025143 A1
`Jan. 23,2014
`(43) Pub. Date:
`
`(54) DEVICES AND METHODS TO REDUCE
`MYOCARDIAL REPERFUSION INJURY
`
`(71) Applicant: Prospex Medical III, New Brighton,
`MN (US)
`
`(72)
`
`Inventors: Robert Atkinson, White Bear Lake, MN
`(US); Jason Galdonik, Minneapolis,
`MN (US); Peter Keith, Lanesboro, MN
`(US); Paul McLean, North Oaks, MN
`(US)
`
`(73) Assignee: Prospex Medical III, New Brighton,
`MN (US)
`
`(21) Appl.No.: 13/943,605
`
`(22) Filed:
`
`Jul. 16, 2013
`
`Related U.S. Application Data
`(60) Provisional application No. 61/672,528, filed on Jul.
`17, 2012, provisional application No. 61/776,399,
`filed on Mar. 11,2013.
`Publication Classification
`
`(51)
`
`(2006.01)
`
`Int. Cl.
`A61F 7/12
`(52) U.S. Cl.
`CPC ......................................... A61F 7/12 (2013.01)
`USPC ............................................................ 607/105
`ABSTRACT
`(57)
`Devices and methods that mitigate reperfusion injury (RI) in
`a clinically practical manner so as to avoid significantly
`increasing time to reperfusion. In general, these systems and
`methods involve an antegrade approach to deliver a fluid to
`the myocardium at risk of RI before, during and after reper­
`fusion is established by a percutaneous coronary intervention
`such as aspiration and stenting.
`
`Medtronic
`EX | Y % 0
`Date'?-3-2-1
`
`Debby J. Campeau
`Stirewalt & Associates
`
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`FIG. 1
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`10
`;
`
`______________________________ /
`
`30
`
`Establish hypothermic state
`Meter oxygen delivery
`Reduce reactive oxygen
`species
`Reduce excess calcium
`Balance pH
`Reduce inflammation
`Capture embolic material
`
`>
`
`FIG. 2A
`
`FIG. 2B
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`FIG. 10
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`f 80
`
`X
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`86
`
`215
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`; 1
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`00
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`FIG. 11
`
`FIG. 12
`
`FIG. 13
`
`FIG. 14
`
`FIG. 15
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`250
`
`260
`
`270
`
`280
`
`FIG. 16
`
`FIG. 17
`
`FIG. 18
`
`FIG. 19
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`297
`
`aspiration
`
`297
`
`FIG. 20
`
`FIG. 21
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`330
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`FIG. 25
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`331
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`FIG. 26
`
`FIG. 27
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`297
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`FIG. 28
`
`FIG. 29
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`FIG. 30
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`297
`
`350
`
`340
`
`FIG. 31
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`FIG. 32
`
`363
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`297
`
`FIG. 33
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`340
`
`360
`
`342
`
`FIG. 34
`
`360
`
`FIG. 35
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`370
`
`2 L
`
`FIG. 37
`
`376
`
`B
`i
`i
`
`B
`
`C
`i
`i
`C
`
`372
`
`_A
`
`i A
`
`FIG. 37 A-A
`
`373
`
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`100
`
`FIG. 38
`
`FIG. 39
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`FIG. 40
`
`80
`
`298
`
`29 7
`
`100
`
`297
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`374
`
`FIG. 42
`
`372
`
`371
`
`372
`
`FIG. 42 A-A
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`2014/0025143 Al
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`A
`
`376
`
`o
`
`j
`
`B
`
`B
`
`J
`
`B
`
`370
`
`i
`
`J
`A
`
`375
`
`FIG. 43
`
`FIG. 43 A-A
`
`FIG. 43 B-B
`
`372
`
`375
`
`FIG. 44
`
`Ai
`
`J
`
`A
`
`375.
`
`370
`
`FIG. 44 A-A
`
`FIG. 44 B-B
`
`- // -
`
`375.
`
`375
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`2 2
`
`hJ
`A
`
`370
`
`370
`
`FIG. 45
`
`370
`
`370
`
`375
`
`370N
`
`375
`
`FIG. 45 A-A
`
`370
`
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`

`
`
`
`
`uoneayqnguoneayddyjuaeg
`
`€€JOLZINSPLZ‘EZ‘ue
`
`100
`
`FIG. 48A
`FIG. 48A
`
`FIG. 48B
`
`TV€rIsz00/rt0zSN.
`
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`FIG. 49B
`
`340
`
`FIG. 50A
`
`100
`
`FIG. 50B
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`■ CORONARY
`■HUB
`.FIXTURE
`BATH
`SALINE BAG
`
`FIG. 51A
`
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`CORONARY
`HUB
`FIXTURE
`BATH
`SALINE BAG
`
`FIG. 51B
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`CORONARY
`HUB
`SALINE BAG
`LINE BATH
`
`25
`20
`
`O
`
`FIG. 51C
`
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`Fia 52
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`TISSUE1
`TISSUE2
`TISSUE3
`TISSUE4
`TISSUE5
`HUB
`
`40
`
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`
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`FIG. 53
`
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`US 2014/0025143 A1
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`Jan. 23, 2014
`
`1
`
`DEVICES AND METHODS TO REDUCE
`MYOCARDIAL REPERFUSION INJURY
`
`CROSS-REFERENCE TO RELATED
`APPLICATIONS
`[0001] This patent application claims the benefit of U.S.
`Provisional Patent Application No. 61/672,528, filed Jul. 17,
`2012, entitled Devices and Methods to Reduce Myocardial
`Injury, and U.S. Provisional Patent Application No. 61/776,
`399, filed Mar. 11, 2013, entitled Devices and Methods to
`Reduce Myocardial Injury, the entire disclosures of which are
`incorporated herein by reference.
`
`FIELD OF THE DISCLOSURE
`[0002] Embodiments of the present disclosure describe
`devices and methods that mitigate reperfusion injury (RI) in a
`clinically practical manner so as to avoid significantly
`increasing time to reperfusion
`
`BACKGROUND OF THE DISCLOSURE
`[0003] S-T
`segment elevated myocardial
`infarction
`(STEMI) occurs when a major coronary artery, typically the
`left anterior descending artery, is significantly blocked result­
`ing in ischemia of the myocardium of the left ventricle. This
`results in characteristic changes in an electrocardiogram
`(ECG) recognized as an elevated S-T segment indicating that
`a large portion of the heart is being damaged. Due to the size
`and significance of the affected area, STEMI patients repre­
`sent the highest risk group of patients presenting with acute
`myocardial infarction (AMI). The duration of ischemia, or
`time-to-reperfusion, is a major factor influencing the size of
`the infarct, which is a major determining factor influencing
`acute and chronic clinical outcomes (e.g., mortality, left ven­
`tricular ejection fraction, cardiac functional capacity, conges­
`tive heart failure, etc.).
`[0004] Current medical guidelines call for rapid reperfu­
`sion of the ischemic area through thrombolytic therapy and/or
`primary percutaneous coronary intervention (PPCI) includ­
`ing balloon angioplasty and stenting. The restoration of blood
`flow to the affected area is intended to limit the duration of
`ischemia and reduce the size of the infarct. Clinical trials have
`demonstrated that the sooner reperfusion is established, the
`smaller the size of the infarct and the better the clinical out­
`come, hence the mantra to minimize “door-to-balloon” time.
`However, restoration of blood flow to the ischemic area can
`result in additional injury to the affected area. This phenom­
`enon has been termed reperfusion injury (RI).
`[0005] Reperfusion injury can be defined as dysfunction of
`the heart induced by restoration of blood flow to a previously
`ischemic area. There are four main types of dysfunction
`induced by reperfusion. The first is mechanical dysfunction
`or reduced contractile function of the left ventricular wall.
`The second type of dysfunction is termed the no-reflow phe­
`nomenon. No-reflow is defined as the impedance of blood
`flow to the micro vascular structures of the myocardium
`inhibiting reperfusion of the ischemic area. The third type of
`dysfunction is arrhythmias induced by the reperfusion. The
`final component of reperfusion injury is termed lethal reper­
`fusion injury. Lethal reperfusion injury is defined as contin­
`ued cardiac myocyte (heart muscle) death as a consequence of
`reperfusion. Lethal reperfusion injury has been shown to
`contribute to a significant portion (one third or more) of tissue
`necrosis after ischemia. The mechanisms of lethal reperfu­
`
`sion injury are multifactorial and complex including meta­
`bolic, biochemical and cellular responses to both ischemia
`and reperfusion.
`[0006] A number of strategies have demonstrated reduction
`in infarct size post reperfusion in both animal models an in the
`clinical setting. Although the mechanisms o f these strategies
`are not fully understood, there is a growing body of evidence
`to suggest they can reduce infarct size.
`[0007] One of these strategies involves hypothermia, which
`lias been demonstrated to reduce infarct size. Hypothermia
`involves the reduction of tissue temperature in order to reduce
`metabolic rate and/or enzymatic activity resulting in protec­
`tion of the affected tissues. Therapeutic hypothermia as
`applied to AMI is described in more detail by Hale et al., Mild
`hypothermia as a cardioprotective approach fo r AMI: lab to
`clinical application, 2011.
`[0008] Whole body cooling, by external and internal
`means, has been used to induce therapeutic hypothermia.
`Examples of external cooling devices include ice baths, cold
`packs and cooling blankets. Examples of internal cooling
`devices include a balloon catheter placed in the vena cava,
`where cold fluid is circulated through the balloon to cool the
`passing blood. In general, whole body cooling systems
`require a significant amount of time to achieve the desired
`temperature drop, which is at odds with the effort to minimize
`door-to-balloon time in STEMI patients.
`
`SUMMARY OF INVENTION
`It is desirable to start therapeutic hypothermia
`[0009]
`before reperfusion, and it is desirable to minimize time to
`reperfusion. Thus, a clinically successful hypothermic inter­
`vention is preferably performed before reperfusion by PPCI
`without significantly increasing door-to-balloon time. This
`represents a significant practical challenge in the clinical
`setting which has thus far eluded a practical solution. The
`present invention provides a number of different embodi­
`ments to address this challenge.
`[0010]
`In general, the present invention provides therapeu­
`tic hypothermia systems and methods that may protect the
`myocardium from reperfusion injury (RI) in a clinically prac­
`tical manner so as to avoid significantly increasing time to
`reperfusion. These systems and methods involve an antegrade
`approach to deliver a fluid to the myocardium at risk o f RI
`before, during and after reperfusion is established by PPCI
`(e.g., dilating the culprit lesion with a balloon catheter/stent).
`A variety of devices, fluids, and procedural steps are dis­
`closed to mitigate RI by, for example: pre-conditioning (e.g.,
`reducing the temperature of) the affected myocardium; con­
`trolling reperfusion dynamics (e.g., flow rate, oxygenation,
`flushing, buffering, etc.) to the affected myocardium, and/or
`post-conditioning the affected myocardium. These systems
`and methods could be used as a stand-alone therapy, or used
`to augment other therapeutic hypothermia approaches (e.g.,
`whole body cooling) and other interventional procedures.
`[0011]
`In embodiments of the present invention, reducing
`the temperature of the affected myocardium may reduce the
`rate of adverse reactions (e.g., toxic oxygen reactions, inflam­
`matory cascades, etc.) associated with RI. Flushing the
`affected myocardium may reduce the presence o f metabolic
`imbalances and adverse agents (e.g., calcium overload, lactic
`acid build-up, etc.) associated with RI. Delivering beneficial
`agents to the downstream vasculature may mitigate vasocon­
`striction and thrombus formation associated with no re-flow.
`Controlling reperfusion to the affected myocardium may
`
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`2
`
`meter the introduction of reagents (e.g., oxygen) that bring
`about adverse reactions (e.g., toxic oxygen species) while
`supporting beneficial reactions (e.g., ATP production).
`[0012] The embodiments of the present invention are
`described herein with reference to STEMI patients, where the
`ischemic myocardium is typically on the anterior side of the
`left ventricle and is typically caused by a restriction in the left
`anterior descending artery. However, the principles of the
`present invention may be applied to other myocardial areas,
`other coronary arteries, and arterial restrictions in other loca­
`tions.
`[0013] Similarly, while specifically useful for treating
`STEMI, the embodiments of the present invention may be
`used for other coronary indications such as all emergent or
`acute coronary syndromes (e.g., acute myocardial ischemia,
`unstable angina, etc.) and all non-emergent or elective coro­
`nary syndromes (e.g., stable angina). In addition, while spe­
`cifically useful for treating the heart, the embodiments of the
`present invention may be used with other organs such as the
`brain (e.g., stroke therapy), lungs (e.g., pulmonary embolism
`therapy) and kidneys (e.g., renal failure).
`[0014]
`In one embodiment, a cold fluid may be delivered
`via an infusion device extending through a guide catheter and
`across the culprit restriction in an artery. The device may
`comprise an infusion guide wire, an infusion catheter, an
`embolic protection (capturing) device, a balloon catheter, or a
`stent delivery catheter, for example, each with a lumen to
`transport the cold fluid. The infusion device may be config­
`ured to be compatible with conventional PPCI hardware (e.g.,
`guide catheters, guide wires, thrombus removal catheters,
`balloon catheters, stent delivery catheters, etc.), and may be
`configured to maximize uninterrupted cooling during the
`PPCI procedure.
`[0015] With the infusion device positioned distally of the
`culprit restriction, the cold fluid may be administered before
`the restriction is opened. Although the act of crossing the
`restriction with the infusion device may partially open the
`restriction, the cold fluid may be administered before the
`restriction is fully dilated. Optionally, an occlusion balloon
`may be provided on the distal end of the infusion device to
`occlude or reduce blood flow in the artery while the cold fluid
`is being delivered. Delivery o f the cold fluid may be main­
`tained during reperlusion and sustained for a period of time
`thereafter.
`[0016] The cold fluid may comprise, for example, a crys­
`talloid solution (e.g. saline), a lactate solution (e.g., Ringer’s),
`a radiopaque contrast solution used for angiographic visual­
`ization, autologous or non-autologous oxygenated (e.g., arte­
`rial) blood, autologous or non-autologous low-oxygenated
`(e.g., venous) blood, and/or a combination thereof. It may be
`desirable to control the rate of oxygen delivery to the affected
`myocardium to mitigate reperfusion injury. Accordingly, the
`cold fluid may have a lower oxygen content than arterial
`blood and/or may be delivered at a slower flow rate to reduce
`the rate of oxygen delivery relative to normal arterial blood
`flow. Reducing the rate of oxygen delivery to the affected
`myocardium is intended to provide a basis for modest ATP
`production while minimizing toxic oxygen reactions. By pro­
`viding a small amount of oxygen to the affected myocardium,
`vital ATP may be produced at a ratio o f 32:1, while toxic
`reactants may be produced at a much lower ratio. In one
`example, the cold fluid is arterial blood, but delivered at a flow
`rate that is well below normal. In another example, the cold
`fluid is crystalloid or the like, which has a much lower oxygen
`
`content than arterial blood, and can be delivered at any physi­
`ological flow rate. In another example, the cold fluid is a mix
`o f the two, the mix ratio o f which can be fixed or varied over
`the treatment time. In each of these examples, the ischemic
`myocardium is receiving some oxygen but less than that
`provided by restored normal blood flow across the restriction
`after dilation by PPCI.
`[0017] Delivery of the cold fluid may be continued until a
`target temperature (e.g., 32 C-35 C) is achieved in the affected
`myocardium. The target temperature may be achieved before
`reperfusion is established across the culprit restriction, main­
`tained during reperfusion, and sustained for a period of time
`thereafter. The temperature of the affected myocardium may
`be indirectly measured using a thermal sensor (e.g., thermo­
`couple) on a distal end of the infusion device, guide catheter
`or other device. Alternatively the temperature could be mea­
`sured using a thermal sensor placed in the liquid before it is
`delivered into the body, such as in the hub of the infusion
`device, in an accessory such as a stop cock or hemostasis
`valve assembly, or in the tubing connecting the infusion
`device to a pump/cooler. The temperature o f the affected
`myocardium may be estimated, for example, by applying the
`temperature measurement from the temperature sensor to an
`algorithm based on an empirically established heat transfer
`model or a thermodynamic model of the heart and coronary
`vasculature that assumes a given blood flow rate in the artery
`(e.g., TIMI flow score).
`[0018] Various other embodiments of the present disclo­
`sure are described in the following detailed description and
`referenced drawings.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`[0019] The drawings illustrate example embodiments of
`the present invention. The drawings are not necessarily to
`scale. Similar elements in different drawings may be num­
`bered the same. In the drawings:
`[0020] FIG. 1 is an anterior view of a human heart illustrat­
`ing the coronary arteries with a restriction in the left anterior
`descending artery affecting the downstream myocardium;
`[0021] FIGS. 2A and 2B are a schematic flow chart and plot
`showing general methods o f the present invention;
`[0022] FIG. 3 is a schematic flow diagram of a typical
`primary percutaneous coronary intervention (PPCI) proce­
`dure showing the timing o f pre-conditioning according to the
`present invention;
`[0023] FIGS. 4 and 5 are schematic diagrams of systems for
`delivering a cold fluid to the left main coronary artery via a
`guide catheter;
`[0024] FIGS. 6 and 7 are schematic diagrams of systems for
`delivering a cold fluid to the left anterior descending artery
`distal of a restriction via a crossing device;
`[0025] FIGS. 8 and 9 are schematic diagrams of systems for
`delivering cold fluids to both the left main coronary artery and
`the left anterior descending artery distal of a restriction.
`[0026] FIG. 10 is a schematic flow diagram of a modified
`PPCI procedure showing steps for using the system shown in
`FIG. 9;
`[0027] FIG. 11 is a schematic drawing of a guide catheter
`for use in any of the systems shown in FIGS. 4-9;
`[0028] FIGS. 12 and 13 are schematic diagrams of a cross­
`ing device in the configuration of an infusion guide wire;
`[0029] FIGS. 14 and 15 are schematic diagrams of a cross­
`ing device in the configuration of an infusion catheter;
`
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`[0030] FIGS. 16 and 17 are schematic diagrams of a cross­
`ing device in the configuration of a balloon catheter;
`[0031] FIGS. 18 and 19 are schematic diagrams of a cross­
`ing device in the configuration of a stent delivery catheter:
`[0032] FIGS. 20-50 are schematic illustrations of various
`intravascular devices that may be used in an antegrade hypo­
`thermia system; and
`[0033] FIGS. 51-53 illustrate empirically derived thermal
`loss data in different models.
`
`DETAILED DESCRIPTION OF THE
`DISCLOSURE
`[0034] With reference to FIG. 1, an anterior view of a
`human heart is shown. The heart includes two main coronary
`arteries: the right coronary and the left coronary artery. The
`right coronary artery generally provides oxygenated blood to
`the myocardium of the right atrium and ventricle, and the left
`coronary artery generally provides oxygenated blood to the
`myocardium of the left atrium and ventricle. Major branches
`of the right coronary artery include the right marginal branch,
`and major branches of the left coronary artery include the left
`anterior descending, the circumflex, the left marginal (branch
`of circumflex), and the left diagonal (branch of left anterior
`descending). Patients with ST elevation myocardial infarc­
`tion (STEMI) often have a restriction in the left anterior
`descending artery affecting the downstream myocardium as
`shown. Although the present invention is described with ref­
`erence to this presentation of STEMI, the principles of the
`present invention may be applied to other clinical presenta­
`tions, other myocardial areas, other coronary arteries, and
`arterial restrictions in other locations.
`[0035] With reference to FIG. 2A, general steps of a
`method 10 for mitigating reperiusion injury according to an
`embodiment o f the present invention are shown schemati­
`cally with reference to general objectives 30. The method 10
`may be broken down into three generalized steps (16, 20,24)
`relative to the time at which antegrade coronary artery access
`is established 14, relative to the time reperfusion across the
`culprit restriction is established 18, and relative to the time
`stabilized reperiusion is established 22. The myocardial tem­
`perature 40 relative to each step is graphically represented by
`the plot in FIG. 2B, which i s representative but not necessarily
`to scale.
`[0036] The step 14 of accessing to the coronary artery may
`be accomplished using a guide or diagnostic catheter as is
`common in PCI procedures. Access to the coronary artery
`typically represents the first instance where focal cooling may
`be administered using conventional steps in PCI. Immedi­
`ately after or coincident with establishing access 14, the
`affected myocardium or myocardium at risk may be focally
`pre-conditioned 16 via the established antegrade access.
`[0037] The step of pre-conditioning 16 may involve estab­
`lishing a mild hypothermic state in the affected myocardium
`at a temperature below normal body temperature (37 C) but
`above a temperature associated with adverse cardiac effects
`such as arrhythmia. Some clinical literature sources report no
`beneficial effect at 36 C, but significant beneficial effect at or
`below 35 C. Other clinical literature sources report adverse
`cardiac events below 32 C. Thus, the target temperature zone
`may be 32 C to 35 C. However, to the extent that the hypoth­
`ermic state is localized to only a portion of the myocardium
`(as opposed to the whole heart and/or the whole body), it may
`be safe to target a myocardial temperature below 32 C.. Thus,
`
`the target myocardial temperature zone of 32 C-35 C as
`shown in FIG. 2B is provided by way of example, not neces­
`sarily limitation.
`[0038] The pre-conditioning 16 may also involve flushing
`adverse agents (reactive oxygen species, excess calcium, lac­
`tic acid, inflammatory agents) from the affected myocardium
`and/or delivering beneficial agents (vasodilators, thrombolyt-
`ics, etc.) to the downstream vasculature. This may be accom­
`plished, for example, by delivering a cold fluid via the guide
`or diagnostic catheter seated in the coronary artery. Alterna­
`tively or in addition, this may be accomplished by delivering
`a cold fluid via a crossing device extending across the culprit
`restriction. Reducing the temperature of the affected myocar­
`dium is intended to reduce the rate of adverse reactions (e.g.,
`toxic oxygen reactions, inflammatory cascades, etc.) associ­
`ated with reperfusion injury. Flushing the affected myocar­
`dium is intended to reduce the presence of metabolic imbal­
`ances and adverse agents (e.g., calcium overload, lactic acid
`build-up, etc.) associated with reperiusion injury. Delivering
`beneficial agents to the downstream vasculature is intended to
`mitigate vasoconstriction and embolic formation associated
`with no re-flow after reperiusion. The step of focal pre-con-
`ditioning 16 may begin as soon as possible after coronary
`artery access 14 is established in order to reach the myocar­
`dial target temperature zone before reperiusion 18 is estab­
`lished as shown in FIG. 2B. Also as shown in FIG. 2B,
`reperfusion across the culprit restriction 18 may be initiated
`once the myocardial temperature 40 is within the target zone.
`The myocardial temperature 40 may be maintained within the
`target zone from a time prior to or coincident with reperfusion
`18 through the end 26 of post-conditioning 24, at a constant or
`minimally fluctuating manner as seen in FIG. 2B.
`[0039] The step of controlling reperfusion dynamics 20
`may involve continuing the pre-conditioning measures 16 as
`well as metering oxygen delivery to the affected myocardium
`by controlling the flow rate and/or oxygen concentration in
`the cold fluid being delivered past the restriction. Reperfusion
`injury may begin immediately upon establishing reperfusion
`18, and may be most significant in the first 5 minutes there­
`after. Therefore, it may be desirable to control reperiusion
`dynamics 20 coincident with but no greater than 5 minutes
`after the initiation of reflow across the restriction 18. Reper­
`iusion 18 may occur when the restriction is aspirated, dilated
`by a balloon catheter, and/or dilated by a stent delivery cath­
`eter. Thus, whichever device (guide wire, thrombus removal
`catheter, balloon catheter, or stent delivery catheter) is used to
`establish the first instance of reperiusion 18, it may be desir­
`able to configure that device to control reperfusion dynamics
`20. In general, the step of controlling reperiusion dynamics
`20 to the affected myocardium is intended to meter the intro­
`duction of reagents (e.g., oxygen) that bring about adverse
`reactions (e.g., toxic oxygen reaction) while supporting ben­
`eficial reactions (e.g., ATP production).
`[0040] Controlling reperiusion dynamics 20 may also
`involve embolic protection using a known emboli capturing
`device deployed downstream (distal) of the restriction.
`Embolic material captured during reperiusion and after rep­
`eriusion may be aspirated using known thrombus removal
`catheters.
`[0041] The step of post-conditioning 24 may involve con­
`tinuing the pre-conditioning measures 14 and/or the reperiu-
`sion measures 18. For example, it may be desirable to con­
`tinue mild hypothermia, continue
`flushing, continue
`medication, and/or continue metering oxygen. This may be
`
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`Jan. 23,2014
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`4
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`done after PCI is complete and stable reflow is established 22.
`For example, to facilitate post-conditioning 24, the guide
`catheter may remain in place in the coronary artery through
`which cold fluid may continue to be administered . In addition
`or as an alternative, the crossing device may remain in place
`across the dilated restriction through which oxygen may con­
`tinue to be metered. This may be initiated in the cath lab and
`continued in the recovery room, for example, and may last 30
`to 120 minutes. Because the typical recovery room is not
`equipped with angiography capability, it may be desirable to
`incorporate an anchoring balloon on the distal end of the
`guide catheter and/or the crossing device to stabilize the same
`in the coronary artery. To avoid thrombus formation in the
`guide catheter and/or crossing device, it may be desirable to
`continuously flush the same with the either the cold oxygen
`controlled fluid or a neutral fluid until the device is removed.
`If desired, the step of post-conditioning 24 may be performed
`with a retrograde approach via the coronary sinus. After the
`post-conditioning 24 is complete 26, the myocardium may be
`allowed to return to normal temperature as shown in FIG. 2B.
`[0042] With reference to FIG. 3, the basic steps involved in
`a typical primary percutaneous coronary intervention (PPCI)
`procedure are shown in a flow chart. Once a patient has been
`diagnosed as having a STEMI and the cath lab personnel have
`been notified, the cath lab is prepared SO to receive the patient.
`Once the patient is in the cath lab and prepped, a needle, wire
`and access sheath are used to establish arterial access, usually
`in the femoral artery or radial artery. A guide (or diagnostic)
`catheter is then routed 54 to the right or left coronary artery
`and radiopaque contrast media is injected 56 into the coro­
`nary arteiy via the catheter while taking x-ray images to
`produce an angiogram. Once the culprit restriction is identi­
`fied by angiography, a guide wire is advanced 58 through the
`guide catheter