Patent Description:
Heart failure affects <NUM>% of North Americans and is the leading hospital discharge diagnosis. The diagnosis of heart failure is accompanied by a survival outlook that is comparable to a major cancer. There are limited rehabilitation options available to patients who are suffering with heart failure, and few strategies actually re-power the heart. Cardiac transplantation remains the gold-standard therapeutic intervention for patients with end-stage heart failure, with an increasing number of individuals being added to the transplant wait list every year. However, wider application of this life-preserving intervention is limited by the availability of donors. Data from the International Society of Heart and Lung Transplantation Registry shows that cardiac transplantation is in progressive decline in suitable donors (<NPL>). Two hundred and fifty eight Canadians have died during the last decade (<NUM> - <NUM>; Heart and Stroke Foundation of Canada) while waiting for heart transplantation. Similarly, in the United States, <NUM> patients died in <NUM> alone while waiting for heart transplantation (Organ Procurement and Transplantation Network, US Dept. of Health & Human Services). This phenomenon is primarily due to a shortage of suitable organ donors, and is being experienced across the globe.

Time is of the essence for removal of a heart from a donor and its successful transplantation into a recipient. The following principles generally apply for optimal donor heart preservation for the period of time between removal from the donor and transplantation: (i) minimization of cell swelling and edema, (ii) prevention of intracellular acidosis, (iii) prevention of injury caused by oxygen free radicals, and (iv) provision of substrate for regeneration of high-energy phosphate compounds and ATP during reperfusion. The two main sources of donor hearts for transplantation are breathing patients who have suffered irreversible loss of brain function as a result of blunt head trauma or intracerebral hemorrhage and are classified as "brainstem-dead" donors, and patients who have suffered circulatory death and are referred to as "non-heart-beating" donors.

Brainstem-dead organ donors can be maintained under artificial respiration for extended periods of time to provide relative hemodynamic stability up throughout their bodies until the point of organ retrieval. Therefore, cardiac perfusion is uncompromised and organ functionality is theoretically maintained. However, brainstem death itself can profoundly affect cardiac function. The humoral response to brainstem death is characterized by a marked rise in circulating catecholamines. Physiological responses to this "catecholamine storm" include vasoconstriction, hypertension and tachycardia, all of which increase myocardial oxygen demand. In the coronary circulation Significant increased levels of catecholamine circulating throughout the vascular system induce vasoconstriction which in turn, compromises myocardial oxygen supply and can lead to subendocardial ischemia. This imbalance between myocardial oxygen supply and demand is one factor implicated in the impairment of cardiac function observed following brainstem death (<NPL>; <NPL>). Structural myocardial damage occurring after brainstem death is characterized by myocytolysis, contraction band necrosis, sub-endocardial hemorrhage, edema and interstitial mononuclear cell infiltration (<NPL>). In spite of no direct cardiac insult, brainstem-dead donors often exhibit reduced cardiac function and the current views are that only <NUM>% of hearts can be recovered from this donor population for transplantation.

Well-defined criteria have been developed for harvesting organs for transplantation from non-heart-beating donors (<NPL>; <NPL>). Non-heart-beating donors have minimal brain function but do not meet the criteria for brainstem death and therefore, cannot be legally declared brainstem dead. When it is clear that there is no hope for meaningful recovery of the patient, the physicians and family must be in agreement to withdraw supportive measures. Up to this point in care, non-heart-beating patients are often supported with mechanical ventilation as well as intravenous inotropic or vasopressor medication. However, only those with single system organ failure (neurologic system) can be considered for organ donation. Withdrawal of life support, most commonly the cessation of mechanical ventilation, is followed by anoxic cardiac arrest after which, the patient must remain asystolic for five minutes before organ procurement is allowed. Consequently, non-heart-beating donors are necessarily exposed to variable periods of warm ischemia after cardiac arrest which may result in various degrees of organ damage. However, provided that the time duration of warm ischemia is not excessive, many types organs, i.e., kidneys, livers, and lungs, harvested from non-heart-beating donors are able to recover function after transplantation with success rates that approximate those for transplanted organs from brainstem-dead beating donors.

Numerous perfusion apparatus, systems and methods have been developed for ex vivo maintenance and transportation of harvested organs. Most employ hypothermic conditions to reduce organ metabolism, lower organ energy requirements, delay the depletion of high energy phosphate reserves, delay the accumulation of lactic acid, and retard morphological and functional deteriorations associated with disruption of oxygenated blood supply. Harvested organs are generally perfused in these systems with preservative solutions comprising antioxidants and pyruvate under low temperatures to maintain their physiological functionality. However, it has been found that increasing amounts of free radicals and catalytic enzymes are produced during extended maintenance of harvested organs in pulsing pressurized hypothermic systems. Fluctuating perfusion pressures in such systems can damage the organs by washing off their vascular endothelial lining and traumatize the underlying tissues. Furthermore, the harvested organs will elute increasing amounts of intracellular, endothelial and membrane constituents resulting in their further physiological debilitation.

The short-comings of hypothermic apparatus, systems and methods have been recognized by those skilled in these arts, and alternative apparatus, systems and methods have been developed for preservation and maintenance of harvested organs at temperatures in the range of about <NUM>° C to about <NUM>° C, commonly referred to as "normothermic" temperatures. Normothermic systems typically use perfusates based on the Viaspan formulation supplemented with one or more of serum albumin as a source of protein and colloid, trace elements to potentiate viability and cellular function, pyruvate and adenosine for oxidative phosphorylation support, transferrin as an attachment factor; insulin and sugars for metabolic support, glutathione to scavenge toxic free radicals as well as a source of impermeant, cyclodextrin as a source of impermeant, scavenger, and potentiator of cell attachment and growth factors, a high Mg++ concentration for microvessel metabolism support, mucopolysaccharides for growth factor potentiation and hemostasis, and endothelial growth factors (Viaspan comprises potassium lactobionate, KH<NUM>PO<NUM>, MgSO<NUM>, raffinose, adenosine, glutathione, allopurinol, and hydroxyethyl starch). Other normothermic perfusion solutions have been developed and used (<NPL>). While harvested kidneys and livers can be maintained beyond twelve hours in normothermic systems, it has become apparent that normothermic bathing, and maintenance of harvested hearts by pulsed perfusion beyond <NUM> hours results in deterioration and irreversible debilitation of the hearts' physiological functionality. Another disadvantage of using normothermic continuous pulsed perfusion systems for maintenance of harvested hearts is the time required to excise the heart from a donor, mount it into the nomothermic perfusion system and then initiate and stabilize the perfusion process. After the excised heart has been stabilized, its physiological functionality is determined and if transplantation criteria are met, then the excised heart is transported as quickly as possible to a transplant facility.

Current technologies employ occlusive roller pumps to provide flow of perfusate into an isolated aortic root. With this approach, the heart cannot eject against the pump without a significant rise in systolic stress. Furthermore, there currently is no device in the market that allows comprehensive assessment of right and left ventricular systolic and diastolic function, in addition to providing metabolic assessments of excised hearts.

<CIT> discloses a perfusion apparatus for pre-transplant maintenance and assessment of an excised donor heart. The apparatus is interconnected with a perfusate-processing system; a bi-directional perfusate pumping system; flow sensors for monitoring the flow of perfusate to and from an installed heart's aorta, pulmonary artery, pulmonary vein, and vena cava; and an ECG apparatus interconnectable with the installed heart, and probes interconnecting the installed heart with instruments for monitoring the heart's physiological functionality.

The present disclosure pertains to an apparatus for maintenance and transport of an excised donor heart.

The apparatus may comprise a first component for receiving and submerging an excised heart in a constantly circulating perfusate solution, a second component comprising equipment for adjusting the temperature and oxygen content of the perfusate solution, a third component comprising a non-occlusive centrifugal pump to pump perfusate into an isolated aortic root of an excised heart during preservation mode and to provide non-occlusive resistance to ejection (afterload) during working/assessment mode, and a fourth component comprising a non-occlusive centrifugal pump to provide filling of the excised heart (preload) during working/assessment mode. By positioning the pumps below the heart, coupled with the non-occlusive nature of the pumps, decompression of the excised heart is provided in the event of poor cardiac function or arrhythmias. The need for gravity as an energy source for provision of preload or afterload to excised hearts is obviated in the current design, thus permitting a compact, portable design for the apparatus of the present disclosure.

A system, not forming part of the present invention, generally comprises the apparatus into which an excised heart is installed, wherein the apparatus is interconnected with: (i) a perfusate pumping system, (ii) flow sensors for monitoring the flow of perfusate to and from the installed heart's aorta, pulmonary artery, pulmonary vein, and vena cava, (iii) an ECG apparatus interconnectable with the excised heart, and (iv) probes interconnecting the installed heart with instruments for monitoring the excised heart's physiological functionality using load independent indices and load dependent indices.

The present invention will be described in conjunction with reference to the following drawings in which:.

In order that the invention herein described may be fully understood, the following terms and definitions are provided herein.

The word "comprise" or variations such as "comprises" or "comprising" will be understood to imply the inclusion of a stated integer or groups of integers but not the exclusion of any other integer or group of integers.

The term "about" or "approximately" means within <NUM>%, preferably within <NUM>%, and more preferably within <NUM>% of a given value or range.

The term "modulate" as used herein means to regulate the operation of a device by increasing a signal to the device in order to increase an output by the device, or by decreasing a signal to the device in order to decrease an output by the device.

The term "afterload" means the mean tension produced by a chamber of the heart in order to contract. It can also be considered as the 'load' that the heart must eject blood against. Afterload is therefore a consequence of aortic large vessel compliance, wave reflection and small vessel resistance (left ventricular afterload) or similar pulmonary artery parameters (right ventricular afterload).

The term "preload" refers to the stretching of a single cardiac myocyte immediately prior to contraction and is therefore related to the sarcomere length. Since sarcomere length cannot be determined in the intact heart, other indices of preload such as ventricular end diastolic volume or pressure are used. As an example, preload increases when venous return is increased.

The term "cardiac myocyte" means a cardiac muscle cell.

The term "stroke volume" (SV) means the volume of blood ejected by the right/left ventricle in a single contraction. It is the difference between the end diastolic volume (EDV) and the end systolic volume (ESV). Mathematically, SV = EDV - ESV. The stroke volume is affected by changes in preload, afterload and inotropy (contractility). In normal hearts, the SV is not strongly influenced by afterload whereas in failing hearts, the SV is highly sensitive to afterload changes.

The term "stroke work" (SW) refers to the work performed by the left or right ventricle to eject the stroke volume into the aorta or pulmonary artery, respectively. The area enclosed by the pressure/volume loop is a measure of the ventricular stroke work, which is a product of the stroke volume and the mean aortic or pulmonary artery pressure (afterload), depending on whether one is considering the left or the right ventricle.

The term "ejection fraction" (EF) means the fraction of end diastolic volume that is ejected out of the ventricle during each contraction. Mathematically, EF = SV/EDV. Healthy ventricles typically have ejection fractions greater than <NUM>. Low EF usually indicates systolic dysfunction and severe heart failure can result in EF lower than <NUM>. EF is also used as a clinical indicator of the inotropy (contractility) of the heart. Increasing inotropy leads to an increase in EF, while decreasing inotropy decreases EF.

The term "end systolic pressure volume relationship" (ESPVR) describes the maximal pressure that can be developed by the left ventricle at any given left ventricular volume, or alternatively, by the right ventricle at any given right ventricular volume. This implies that the PV loop cannot cross over the line defining ESPVR for any given contractile state. The slope of ESPVR (Ees) represents the end-systolic elastance, which provides an index of myocardial contractility. The ESPVR is relatively insensitive to changes in preload, afterload and heart rate. This makes it an improved index of systolic function over other hemodynamic parameters like ejection fraction, cardiac output and stroke volume. The ESPVR becomes steeper and shifts to the left as inotropy (contractility) increases. The ESPVR becomes flatter and shifts to the right as inotropy decreases.

The term "preload recruitable stroke work relationship" (PRSW) means a measure of cardiac contractility, and is the linear relationship between SW and EDV.

The term "pressure-volume area" (PVA) means the total mechanical energy generated by ventricular contraction. This is equal to the sum of the stroke work (SW), encompassed within the PV loop, and the elastic potential energy (PE). Mathematically, PVA = PE + SW.

The term "Langendorff perfusion" refers to a method of perfusing an excised heart with a nutrient-rich oxygenated solution in a reverse fashion via the aorta. The backwards pressure causes the aortic valve to shut thereby forcing the solution into the coronary vessels, which normally supply the heart tissue with blood. This feeds nutrients and oxygen to the cardiac muscle, allowing it to continue beating for several hours after its removal from the animal.

The term "working heart" as used herein, refers to clinical ex vivo coronary perfusion throughout a excised heart by ventricular filling via the left atrium and ejection from the left ventricle via the aorta driven by the heart's contractile function and regular cardiac rhythm. The excised heart is attached by cannulae to a perfusate reservoir and circulatory pumps in a Langendorff preparation. The flow of perfusate through the excised heart in "working heart" mode is in the direction opposite to the flow of perfusate during Langendorff perfusion.

The term "ischemia" means a condition that occurs when blood flow and oxygen are kept from the heart.

The term "conduit" as used herein means tubing and/or cannula.

The present disclosure pertains to apparatus for maintaining an excised heart under continuous Langendorff perfusion until transplantation. The apparatus and systems are communicable and cooperable with cardiac monitoring equipment and microprocessors for monitoring the physiological condition and functioning of the excised heart.

A modular apparatus for receiving and maintaining an excised heart under continuous Langendorff perfusion until transplantation comprises two modules. The first module comprises a hard-shell reservoir, also referred to herein as a reservoir, for housing therein an excised heart under constant bathing with a suitable perfusate solution. The excised heart is mounted onto a stand and submerged within the hard-shell reservoir. The hard-shell reservoir is provided with four ports (i.e., two egress ports and two ingress ports) that are sealingly engageable by conduits that have been interconnected to the excised heart's right atrium, left atrium, aorta, and pulmonary artery. The second module is a perfusate conditioning apparatus comprising: (i) a heat-exchanger for warming and maintaining the perfusate solution at a user-specified temperature (typically referred to as a normothermic temperature), and (ii) and oxygenator for maintaining the dissolved oxygen levels in the perfusate solution above <NUM>% saturation, and maintaining the pH balance through addition of carbon dioxide. The two modules are interconnected by a conduit infrastructure that is engageable by a pump such as those exemplified by centrifugal pumps. Suitable centrifugal pumps are exemplified by ROTAFLOW® centrifugal pumps (ROTAFLOW is a registered trademark of Maquet Cardiopulmonary AG Corp. , Hirrlingen, Fed. ), by Medtronic's centrifugal blood BIO-PUMP®s BIO-PUMP is a registered trademark of Medtronics Bio-Medicus Inc. , Minnetonka, MN, USA), by Sorin's RevOlution <NUM> blood pump (Sorin Group USA, Arvada, CO, USA). In operation, the centrifugal pump provides a constant flow of perfusate solution from the first module (i.e., the hard-shell reservoir) to the second module (i.e., the perfusate conditioning apparatus). The first module is additionally provided with ports for receiving therethrough leads from cardiac monitoring equipment for engaging specific sites on and/or in the excised heart. Each module can be separately assembled and prepared for use multiple units, thereby facilitating rapid assembly and configuration of the apparatus as needed to receive and maintain an excised heart.

An exemplary apparatus <NUM> according to one embodiment of the present disclosure is shown in <FIG>. The apparatus comprises: (i) a first component which is a hard-shell reservoir <NUM> housing a removable support (not shown) for mounting thereon and therein an excised heart <NUM>, and (ii) a second component which is a perfusate solution conditioning device <NUM> comprising a heat-exchanger <NUM> and an oxygenator <NUM>. The hard-shell reservoir <NUM> may additionally have a level sensor (not shown) for monitoring the level of perfusate solution in the hard-shell reservoir <NUM>. The two components are interconnected by a first conduit infrastructure comprising: (i) an egress line <NUM> that is sealably engageable at one end with a port <NUM> provided therefore near the bottom of the hard-shell reservoir <NUM> and is sealably engageable at its other end with the inlet of a first centrifugal pump <NUM>. The outlet of the first centrifugal pump <NUM> is sealably engaged with a line <NUM> that is sealably engageable with an inlet to the heat exchanger <NUM> of the perfusate solution conditioning device <NUM>. A line <NUM> is sealably engageable with an outlet from the oxygenator <NUM> of the perfusate solution conditioning device <NUM>. The other end of line <NUM> is sealably engageable with a Y-connector <NUM> which diverts a portion of the flow of conditioned perfusion solution from the perfusion solution conditioning device <NUM> into a purge line <NUM> that is sealably engageable with a first ingress port <NUM> provided therefore on the hard-shell reservoir <NUM>. The remainder of the flow of perfusate solution conditioning device <NUM> is diverted by the Y-connector <NUM> into a flow sensor <NUM> interconnected with an integrated pressure port <NUM> that is clampable into the aorta <NUM> of the harvested heart. In operation, the flow sensor <NUM> measures aortic flow of the conditioned perfusion solution from the perfusate solution conditioning device <NUM> into the aorta <NUM>. Perfusion solution egressing from the hard-shell reservoir <NUM> into the perfusate solution conditioning device <NUM> is conditioned by heating in the heat exchanger <NUM> to a normothermic temperature from the range of about <NUM>° C to about <NUM>° C and then is oxygenated by oxygenator <NUM> prior to flowing into line <NUM> for conveyance into the aorta <NUM>. The diastolic pressure in the aorta <NUM> can be specified and tightly regulated by computer controlled feedback to modulate the centrifugal pump <NUM>. During assessment mode, with provision of flow into the left atrium the heart ejects the perfusion solution back through line <NUM> with the centrifugal pump <NUM> providing resistance (afterload). In this manner the heart can beat against an afterload pressure that is delivered by the flow of perfusate solution from the centrifugal pump <NUM>.

A second conduit infrastructure comprises a line 60a sealably engageable at one end with a second egress port <NUM> provided therefore near the bottom of the hard-shell reservoir <NUM>, and its other end sealably engageable with the inlet into a second centrifugal pump <NUM>. The outlet of the second centrifugal pump <NUM> is sealably engageable with a line 60b that terminates in a Y-connector <NUM>. Y-connector <NUM> splits the pressurized flow of perfusion solution into two lines <NUM>, <NUM>. Line <NUM> is interconnected with, firstly, an occlusion clamp <NUM>, secondly, a flow sensor <NUM>, and thirdly, an integrated pressure port <NUM>. The terminal end of line <NUM> is insertable into the right atrium <NUM> of the harvested heart <NUM>. It should be noted that occlusion clamp <NUM> is preferably a servo-actuated partial occlusion clamp whose variable positions enables regulation of the rate of flow of the perfusion solution into the right atrium <NUM> and therefore, can also be used to modulate pressure delivered to the harvested heart <NUM>. Line <NUM> is interconnected with, firstly, a flow sensor <NUM>, and secondly, an integrated pressure port <NUM>. The terminal end of line <NUM> is insertable into the left atrium <NUM> of the harvested heart <NUM>. It should be noted that lines <NUM>, <NUM> are additionally provided with bubble detectors (not shown). During the assessment mode, pump <NUM> provides flow of the perfusate solution into the right atrium and left atrium (preload pressure) under a feedback loop from pressure ports <NUM>, <NUM> with differential control of flow into the right atrium and left atrium being provided by modulation of clamp <NUM>. In the event of overpressurization of the heart as a consequence, for example, of arrhythmia or poor cardiac function, the flow of perfusate solution from pump <NUM> is decreased thereby allowing decompression of the heart to occur through passive retrograde flow of the perfusate solution back through the pump <NUM>.

A third conduit infrastructure comprises a line <NUM> that is clampable into the pulmonary artery <NUM> of the harvested heart <NUM>. The line <NUM> is sequentially sealably engageable with an integrated pressure port <NUM>, a flow sensor <NUM>, and a third centrifugal pump <NUM>. The terminal end of the line <NUM> is sealably engageable with the second ingress port <NUM> provided therefore on the hard-shell reservoir <NUM>. Pump <NUM> provides resistance (afterload pressure) to the right ventricle, through computer-controlled modulation of the pump <NUM> in reference to feedback from pressure port <NUM>.

<FIG> illustrates exemplary monitoring and maintenance equipment for maintaining a harvested heart in a functional condition during storage and transport in the exemplary apparatus of the present disclosure. Leads <NUM> from an ECG monitoring device <NUM> are engageable with, for example, the right ventricle <NUM> and the left ventricle <NUM> of a harvested heart <NUM> for monitoring the electrical activity of the harvested heart <NUM>. Alternatively, the ECG leads may be integrally incorporated into the walls of the hard-shell reservoir <NUM>. Leads <NUM> from a dual-chamber pacemaker <NUM> are engageable with the right atrium <NUM> and the right ventricle <NUM> of the harvested heart <NUM>. Although a dual-chamber pacemaker is preferable for use with the apparatus <NUM> of the present disclosure, it is optional to substitute a single-chamber pacemaker having a single lead that is engageable with the right atrium or the right ventricle. Two defibrillator pads <NUM> are integrally provided opposite each other on the inner surfaces of the hard-shell reservoir <NUM> and are connected by leads <NUM> to a defibrillator. The ECG monitoring device <NUM>, the pacemaker <NUM> and the defibrillator <NUM> may be mounted on a support provided therefore (not shown) that is an integral component of the hard-shell reservoir <NUM>. Alternatively, the ECG monitoring device <NUM>, the pacemaker <NUM> and the defibrillator <NUM> may be integrally incorporated into the housing of a transportation container configured to receive therein the hard-shell reservoir <NUM>.

As soon as an excised heart <NUM> is mounted onto the removable support and placed into the hard-shell reservoir <NUM>, the terminal end of line <NUM> is clamped into the aorta, <NUM>, line <NUM> is inserted into the right atrium <NUM>, line <NUM> is inserted into the left atrium <NUM>, and line <NUM> is clamped into the pulmonary artery <NUM>. Then, a suitable perfusion solution exemplified by whole blood, whole blood amended with citrate and/or phosphate and/or dextrose, modified Krebs solutions, Viaspan, modified Viaspan solutions, and the like, is added into the hard-shell reservoir <NUM> until the heart <NUM> is completely submerged. It should be noted that the hard-shell reservoir <NUM> may be additionally provided with a level sensor (not shown) and a supplementary supply of the perfusion solution (not shown) for conveyance into the hard-shell reservoir <NUM> as need to maintain the excised heart <NUM> fully submerged during storage and transport in the apparatus of the present disclosure.

When in operation, the pump <NUM> continuously draws the perfusate solution from the hard-shell reservoir <NUM> from egress port <NUM> into line <NUM> into the perfusate solution conditioning device <NUM> wherein the perfusate solution is conditioned by warming to a normothermic temperature and then, is oxygenated. The conditioned and pressurized conditioned perfusate solution is then conveyed to Y-connector <NUM> that diverts a portion of the conditioned perfusate solution into purge line <NUM> for conveyance through ingress port <NUM> back into the hard-shell reservoir <NUM> where it circulates about and baths the heart <NUM>. The remaining flow of pressurized conditioned perfusate solution is conveyed through flow sensor <NUM> and integrated pressure port <NUM> into the aorta <NUM>. It is to be noted that the purge line <NUM> is positioned to be the highest point in the assembled apparatus <NUM> when an excised heart <NUM> is mounted therein so that any air that is ejected by the heart immediately goes out via the purge line <NUM> and back to the hard-shell reservoir <NUM>.

A preload centrifugal pump <NUM> draws the perfusion solution out of the hard-shell reservoir through egress port <NUM> into line 60b and then pushes the perfusion solution to Y-connector <NUM> where its flow is split into two lines <NUM>,<NUM>. The perfusion solution is pushed through line <NUM> through a computer-controlled servo-actuated partial occlusion clamp <NUM>, a flow sensor <NUM>, and an integrated pressure port <NUM> into the right atrium <NUM>. The variable positions of the servo-actuated partial occlusion clamp <NUM> enables precise regulation of the rate of flow of the perfusion solution into the right atrium <NUM>. The perfusion solution is concurrently pushed through line <NUM> through a flow sensor <NUM>, and an integrated pressure port <NUM> into the left atrium <NUM>.

The pressurised perfusion solution flowing into the aorta <NUM>, right atrium <NUM>, and left atrium <NUM> flows into the right ventricle <NUM>, and then out through the pulmonary artery <NUM> into line <NUM> through, firstly, an integrated pressure port <NUM>, secondly, a flow meter <NUM>, thirdly, an afterload centrifugal pump <NUM> to regulate the right ventricular afterload pressure (which is measured by the flow meter <NUM>), and finally, back into the hard-shell reservoir <NUM> through ingress port <NUM>. The pressurized flow of conditioned perfusion solution into the aorta <NUM> via line <NUM> is supplied by centrifugal pump <NUM> and is monitored by aortic flow sensor <NUM>. The pressurized flow of conditioned perfusion solution into the aorta <NUM> and then out of the pulmonary artery <NUM> will maintain the heart <NUM> in a Langendorff, isolated root perfusion state. To maintain and assess the heart's function in working mode, tight regulation of preload is required. Therefore lines <NUM>, <NUM> connected to the right atrium and left atrium, respectively, comprise <NUM>/<NUM>" tubing and receive pressurized flow of perfusion solution from the preload pump <NUM>. Right atrial flow pressure is monitored by flow sensor <NUM> while left atrial flow pressure is monitored by flow sensor <NUM>. The computer-controlled servo-actuated partial occlusion clamp <NUM> enables precise control over the rate of perfusion solution to the right atrium <NUM> and the left atrium <NUM>, and therefore, the pressure applied to the receiving chamber. The flow meters <NUM>, <NUM>, <NUM>, <NUM> and the integrated pressure points <NUM>, <NUM>, <NUM>, <NUM> are connectable to and communicable with a computer for constant monitoring and integrating of the flow rates and pressures to enable constant assessment of cardiac function, i.e., the right ventricular stroke work and the left ventricular stroke work while varying resistance to the flow of perfusion solution (i.e., afterload). It should be noted that the levels of haematocrit, Ca++, K+, NaHCO<NUM>, Na+, pO<NUM>, CO<NUM>, and glucose in the perfusion solution must be balanced before perfusion starts. In the case of using bank CPD donor blood, deranged K+ and Ca++ concentrations may not allow for a homeostatic prime. This can be adjusted by haemofiltration using Ringers solution as the rinse. All these values should ideally start within normal physiological ranges and should be monitored by inline continuous blood gas analysis. The primary purpose for the perfusion solution is to avoid causing tissue edema and to maintain ion homeostasis to preserve cardiac function.

The present disclosure relates to a support for mounting thereon and dismounting therefrom of the modules and the pumps. The support may additionally have mounts for installation of cardiac monitoring equipment and/or computer equipment and/or monitors for displaying the physiological condition and functioning of the excised heart. The support may be a racking system mounted on wheels so that the apparatus is transportable within a medical facility, for example between surgical theatres, staging rooms, assembly rooms and disassembly rooms. The support may be a cabinet with two opposing side walls and with other two sides having opening doors. Alternatively, the support may be a cabinet with three fixed side walls being opposing walls and having one side with opening doors. The side walls and doors may be insulated and/or cushioned. The support may be configured for transport by vehicles or by airplanes.

The present disclosure also relates to a system for receiving, perfusing and maintaining and assessing an excised donor heart. The system generally comprises the above-disclosed apparatus interconnected with: (i) a perfusate-processing system, (ii) a perfusate pumping system, (iii) flow sensors for monitoring the flow of perfusate to and from an installed heart's aorta, right atrium, left atrium, and pulmonary artery vena cava, (iv) an ECG apparatus interconnectable with the installed heart, (v) a pacemaker interconnectable with the installed heart, (vi) a defibrillator interconnectable with the pair of defibrillator pads integral with the inner surface of the hard-shell reservoir component of the apparatus, and (vii) probes interconnecting the installed heart with instruments for monitoring the heart's physiological functionality using load independent indices and load dependent indices. Suitable perfusion-processing systems are exemplified by heart-lung machines commonly used for coronary bypass surgeries.

Claim 1:
A modular and portable perfusion apparatus (<NUM>) for maintenance and transport of an excised donor heart (<NUM>), comprising:
a first module comprising a hard-shell reservoir (<NUM>) with a removable support for positioning and mounting thereon the excised heart (<NUM>), said hard-shell reservoir (<NUM>) having a pair of opposing defibrillator pads (<NUM>) engaged with an inner surface of the hard-shell reservoir (<NUM>);
a second module (<NUM>) comprising a heat-exchanger (<NUM>) in communication with an oxygenator (<NUM>);
a transportable support for disengagably mounting thereon the first module and the second module (<NUM>);
a first conduit infrastructure interconnecting the first module, the second module (<NUM>) and an aorta (<NUM>) of the excised donor heart (<NUM>), said first conduit infrastructure having a first centrifugal pump (<NUM>) for pushing a perfusion solution from the first module to the second module (<NUM>);
a second conduit infrastructure for connecting the first module with a right atrium (<NUM>) and a left atrium (<NUM>) of the excised donor heart (<NUM>), said second conduit infrastructure having a second centrifugal pump (<NUM>) for pushing the perfusion solution from the first module to the right atrium (<NUM>) and the left atrium (<NUM>); and
a third conduit infrastructure for connecting the first module with a pulmonary artery (<NUM>) of the excised donor heart (<NUM>), said third conduit infrastructure having a third centrifugal pump (<NUM>) for providing an after pressure to a flow of the perfusion solution from the pulmonary artery (<NUM>).