Pericardial-liquid level control system

Provided is a pericardial-liquid level control system with which a good viewing field can be ensured for an endoscope image without causing cardiac tamponade. A pericardial-liquid level control system is employed, including a sheath that is inserted into the pericardium; pumps that supply and expel liquid to and from the sheath; electrocardiogram electrodes that detect electrocardiographic information; and a pump control device that, in synchronization with the electrocardiographic information detected by the electrocardiogram electrodes, controls the pumps so that the liquid is supplied to the pericardium via the sheath during contraction of the heart and the liquid is expelled from the pericardium via the sheath during expansion of the heart.

TECHNICAL FIELD

The present invention relates to a pericardial-liquid level control system for controlling the amount of liquid in the pericardium.

BACKGROUND ART

In the related art, there is a known technique in which gas such as carbon dioxide or the like is injected into the pericardium in order to ensure a sufficient viewing field for an endoscope image when a device such as an endoscope is inserted into the pericardium and endoscopy or treatment using an instrument is performed in the pericardium (for example, see Patent Literature 1).

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

Filling the pericardium with gas, as in the technique disclosed in Patent Literature 1, causes the followings.

(1) Tissue gets damaged due to drying of the epicardium.

(2) Ultrasonic waves from an ultrasonic probe disposed on a body surface or at an esophageal wall are reflected by a gas layer, thus impeding propagation of the ultrasonic waves.

(3) Electrodes of an electrode catheter inserted into the pericardium are insulated by the surrounding gas, thus impeding transmission of electrical signals.

On the other hand, when liquid is injected into the pericardium, this causes so-called cardiac tamponade in which pulsing of the heart is impeded by the liquid injected into the pericardium.

The present invention provides a pericardial-liquid level control system with which a good viewing field can be ensured for an endoscope image without causing cardiac tamponade.

Solution to Problem

An aspect of the present invention employs a pericardial-liquid level control system including a pipe that is inserted into a pericardium; a pump that supplies and expels liquid to and from the pipe; an electrocardiographic-information detecting portion that detects electrocardiographic information; and a controlling portion that, in synchronization with the electrocardiographic information detected by the electrocardiographic-information detecting portion, controls the pump so that the liquid is supplied to the pericardium via the pipe during contraction of the heart and the liquid is expelled from the pericardium via the pipe during expansion of the heart.

DESCRIPTION OF EMBODIMENTS

First Embodiment

A pericardial-liquid level control system101according to a first embodiment of the present invention will be described below with reference to the drawings.

As shown inFIG. 1, the pericardial-liquid level control system101in this embodiment is provided with pumps1and2that transport a certain amount of liquid, a pump control device (controlling portion)5that controls these pumps1and2, an electrocardiograph (electrocardiogram generating unit)6that sends an electrocardiogram to the pump control device5, electrocardiogram electrodes (electrocardiographic information detecting portions)7aand7bthat are attached to the body surface for measuring the electrocardiogram, a physiological-electrolyte-solution container8in which physiological saline solution is kept, a waste-liquid container9in which liquid expelled from a pericardium C is stored, and a check-valve-equipped cock (flow-channel joining portion)10that combines liquid-feeding routes from the pumps1and2into a single route.

As described later, reference sign14indicates an ultrasonic probe for acquiring an ultrasonic image by emitting ultrasonic waves into a heart B from the body surface.

A liquid-feeding route13that connects the body exterior with the interior of the pericardium C is a tube, and one end thereof is connected to a gap between the inner space of a sheath (pipe)11inserted from below the xiphoid process and a device (an endoscope12in this case) inserted into the sheath11. In addition, the other end of the liquid-feeding route13that connects the body exterior with the interior of the pericardium C is connected to the check-valve-equipped cock10.

The sheath11is preferably a sheath11equipped with a steering mechanism as with, for example, the Agilis steerable sheath11made by St. Jude Medical Co. Ltd., and, similar to a general sheath11, a route (space) thereof that penetrates into the pericardium C is provided with a three-way stop cock (not shown) at the end thereof.

The check-valve-equipped (branched) cock10, such as one shown inFIG. 2, is connected to the three-way stop cock of the sheath11. The check-valve-equipped cock10branches a single flow channel from the sheath11; one of the branched flow channels is provided with a check valve15athat only accepts a flow to be injected towards the sheath11side, and the other flow channel is provided with a check valve15bthat only accepts a flow from the sheath11side.

In the example shown inFIG. 2, although the flow channel is branched into three, and the remaining one is provided with an emergency valve16which is released in the case of an emergency in this example, the emergency valve16may be substituted by the three-way stop cock of the sheath11.

In addition, although the check valves15aand15bare provided for the purpose of preventing a reverse flow from the waste-liquid container9, they need not be provided if a type of pump with which a reverse flow is less likely to occur, such as a peristaltic pump or the like, is employed as the pumps1and2.

The electrocardiogram electrodes7aand7bare electrodes attached to body surfaces for measuring an electrocardiogram (electrocardiographic information) and output the measured electrocardiographic information to the electrocardiograph6.

The electrocardiograph6generates an electrocardiogram from the electrocardiographic information measured by the electrocardiogram electrodes7aand7band outputs the electrocardiogram to the pump control device5.

The physiological-electrolyte-solution container8is a container in which physiological saline solution is retained. The physiological-electrolyte-solution container8is connected to the pump1, and, by operating the pump1, the physiological saline solution retained in the physiological-electrolyte-solution container8is injected into the pericardium C via the check-valve-equipped cock10and the liquid-feeding route13.

Liquid to be injected into the pericardium C, which is a space between a pericardial membrane A and the heart B, is preferably physiological electrolyte solution, such as a physiological saline solution, Ringer's solution, and so forth, and this embodiment will be described by using physiological saline solution which is physiological electrolyte solution.

The waste-liquid container9is a container in which liquid expelled from the pericardium C is stored. The waste-liquid container9is connected to the pump2, and, by operating the pump2, the physiological saline solution retained in the pericardium C is expelled from the pericardium C via the check-valve-equipped cock10and the liquid-feeding route13and is transferred to the waste-liquid container9.

As shown inFIG. 4, the pump control device5controls the pumps1and2in synchronization with the electrocardiogram (the electrocardiographic information measured by the electrocardiogram electrodes7aand7b) generated by the electrocardiograph6. Specifically, the pump control device5operates the pump1when the heart B contracts, to supply the physiological saline solution to the pericardium C via the liquid-feeding route13. On the other hand, the pump control device5operates the pump2when the heart B expands, to expel the liquid from the pericardium C via the liquid-feeding route13.

As shown inFIG. 5, as its functions, the pump control device5is provided with an R-wave detecting portion21that receives signals from the electrocardiograph6and detects R-waves from the electrocardiogram and an operation-signal generating unit22that outputs, to the pumps1and2, an injection operation signal for injecting liquid into the pericardium C from the physiological-electrolyte-solution container8and a suction operation signal for sucking the liquid from the pericardium C into the waste-liquid container9after a predetermined period of time since the time of the R wave detection.

Here, cardiac tamponade is caused by a drop in the cardiac output which is caused by entering the systolic phase without a sufficient expansion of the ventricles due to the liquid in the pericardium C impeding the expansion of the ventricles during the diastolic phase when an excessive amount of liquid is retained in the pericardium C. In other words, if the amount of liquid in the pericardium C is controlled so that the ventricles can sufficiently be expanded at the end of the diastole, the occurrence of cardiac tamponade can be reduced.

Therefore, with the pericardial-liquid level control system101according to this embodiment, as shown inFIG. 3, liquid is injected into the pericardium C during the systole, and the liquid is sucked out of the pericardium C during the diastole in synchronization with the electrocardiogram.

By doing so, because the amount of liquid in the pericardium C at the end of the diastole can be reduced to an amount with which the heart B can sufficiently be expanded at the end of the diastole, the liquid can be retained in the pericardium C without causing cardiac tamponade. In addition, by retaining the liquid in the pericardium C, drying of the epicardium can be prevented, and a sufficient viewing field can also be ensured for an endoscope inserted into the pericardium C by expanding the interior of the pericardium C. Furthermore, it is possible to simultaneously perform ultrasonic observation via the body surface and the esophageal wall, electrode-position detection based on the electrical impedance of the endoscope12inserted into the pericardium C, and so forth.

In addition, it is not only possible to utilize the liquid retained in the pericardium C as an acoustic medium for an ultrasonic endoscope12inserted into the pericardium C or a cooling medium for an ablation endoscope12inserted into the pericardium C, but it is also possible to lift the heart B in the pericardium C with a low force due to the buoyancy of the liquid in the pericardium C, and thus the back wall of the heart B can be more easily accessed.

A method of using the pericardial-liquid level control system101according to this embodiment will be described below.

First, by using the method of Sosa et al. (reference: Sosa E. et al. Nonsurgical transthoracic epicardial catheter ablation to treat recurrent ventricular tachycardia occurring late after myocardial infarction. J. Am. Coll. Cardiol. 2000. 35: 1442-1449), the sheath11(for example, the Agilis steerable sheath11made by St. Jude Medical Co. Ltd.) is indwelt in the pericardium C from below the xiphoid process in the state in which the interior of the sheath11is filled with the physiological saline solution.

Next, in order to ensure a sufficient viewing field for a surface observation of the heart B by means of the endoscope12, the pump1is operated while monitoring the hemodynamics of a patient to inject the physiological electrolyte solution into the pericardium C from the physiological-electrolyte-solution container8via the check-valve-equipped cock10and a gap between the endoscope12and the sheath11.

At this time, by starting to control the amount of physiological electrolyte solution, described later, at the pump control device5to which a signal line from the electrocardiograph6is connected, the physiological electrolyte solution is injected into the pericardium C by means of the pump1during the ventricular systolic phase. In addition, the pump2is operated so as to correspond to the subsequent ventricular diastolic phase, and thus, excess liquid in the pericardium C which causes a failure in the hemodynamics is expelled to the waste-liquid container9from the pericardium C.

FIG. 6shows an example of the control of the amount of physiological electrolyte solution (control of the pumps1and2for injecting and expelling the physiological electrolyte solution) by the pump control device5.

A trigger signal is generated under a trigger condition for capturing R-waves from the electrocardiogram, and a signal for operating the pump1that injects the physiological electrolyte solution into the pericardium C for a certain period of time Δt2after a certain period of time (Δt1) from the initiation of the trigger signal is output to the pump1.

In addition, after a time interval Δt3from when the operating signal for the pump1is turned off, a signal for operating the pump2that expels the physiological electrolyte solution from the pericardium C for a certain period of time Δt4is output to the pump2.

Here, it is necessary to select the respective operating time so as to satisfy the relationship below:
RRinterval(ΔtR-R)>Δt1+Δt2+Δt3+Δt4.

With the pericardial-liquid level control system101according to this embodiment, the amount of liquid in the pericardium C can be stably controlled even if the RR interval (heart-beat movement interval) fluctuates within a range in which the above relationship is satisfied. Therefore, by determining non-response time Δti from the output of one trigger signal to the output of the next trigger signal in the following manner, a trigger-signal output due to noise can be reduced, and the amount of physiological saline solution can be stably controlled:
Δt1+Δt2+Δt3+Δt4<Δti<ΔtR-R.

Subsequently, control is performed so that the amount of physiological saline solution injected from the physiological-electrolyte-solution container8during the time Δt2by means of the pump1and the amount of liquid expelled to the waste-liquid container during the time Δt4by means of the pump2become equal. Although a case in which Δt2is set to be equal to Δt4by making the liquid supplying speed and the liquid discharging speed equal is described as an example here, naturally, there is no limitation thereto, and the liquid feeding/discharging speed and the liquid feeding/discharging time may be adjusted so that the liquid supply level and the liquid discharge level become the same.

As described above, with the pericardial-liquid level control system101according to this embodiment, by increasing the amount of liquid in the pericardium C during the systolic phase, a sufficient space can be ensured in the pericardium C for performing observation by means of the endoscope12or treatment by using an instrument, fogging of a lens in the endoscope12inserted into the pericardium C can also be eliminated, and thus, an endoscope image can be enhanced. In this case, by decreasing the amount of liquid in the pericardium C during the diastolic phase, the effect of the liquid in the pericardium C on the ventricular diastole can be reduced so as not to cause cardiac tamponade.

In addition, damage on the surface of the heart B due to drying of the epicardium can be reduced, and at the same time, an ultrasonic image can be acquired by emitting ultrasonic waves into the heart B from the body surface by means of the ultrasonic probe14.

Although a case in which the ultrasonic probe14is placed on the body surface is illustrated in the example shown inFIG. 1, with the pericardial-liquid level control system101according to this embodiment, there is an advantage in that, also with a transesophageal probe or an ultrasonic probe inserted into the pericardium C, an ultrasonic image can be displayed without requiring a special holding mechanism for an acoustic medium.

Furthermore, because buoyancy acts on the heart B by retaining the physiological electrolyte solution, such as physiological saline solution or the like, in the pericardium C, the heart B can be moved in position in the pericardium C even with a weaker force as compared with a case in which gas, such as carbon dioxide or the like, is retained therein. In particular, when treatment is performed by inserting the endoscope12at the back wall of the heart B, a sufficient work space can be easily ensured by lifting the heart B. In addition, the liquid in the pericardium C can act as a medium for manipulating the endoscope12by utilizing the buoyancy of the liquid.

Second Embodiment

A pericardial-liquid level control system102according to a second embodiment will be described with reference toFIG. 7. Hereinafter, for pericardial-liquid level control systems according to individual embodiments, the same reference signs will be assigned to commonalities with the pericardial-liquid level control system according to the embodiment described above, omitting descriptions thereof, and differences from the pericardial-liquid level control system according to the embodiment described above will mainly be described.

FIG. 7is a diagram showing, in outline, the configuration of the pericardial-liquid level control system102according to this embodiment.

The pericardial-liquid level control system102according to this embodiment differs from the pericardial-liquid level control system101according to the first embodiment in that an injection pathway into the pericardium C for physiological saline solution and a suction pathway from the pericardium C for the physiological saline solution are provided independently of each other.

The three-way stop cock of the sheath11is connected to the pump2that discards the liquid in the pericardium C into the waste-liquid container9by means of suction, and the pump1that injects physiological saline solution into the pericardium C is connected to an unillustrated endoscope through-hole (channel) that is provided as an opening at the tip of the endoscope12so as to communicate with the interior of the endoscope12inserted into the sheath11.

With the pericardial-liquid level control system102according to this embodiment, because fresh physiological saline solution is supplied to the vicinity of the tip of the endoscope12, in addition to the same effects as the first embodiment, a high clearness can be maintained for the physiological saline solution in the pericardium C and a clear image can be acquired by means of the endoscope12.

Third Embodiment

A pericardial-liquid level control system103according to a third embodiment will be described with reference toFIGS. 8 to 11.

FIG. 8is a diagram showing, in outline, the configuration of the pericardial-liquid level control system103according to this embodiment.

In this embodiment, an example will be described in which a position detection system for the endoscope12based on electric impedance is employed in the pericardial-liquid level control system101according to the embodiment described above. Here, a case in which, for example, the position detection function of the EnSite NavX system made by St. Jude Medical Co. Ltd. is employed as an endoscope-position detection system based on electrical impedance will be described as an example.

With the EnSite NavX system made by St. Jude Medical Co. Ltd., in order to establish a three-axis electrical potential gradient in a biological subject, pairs of patch electrodes31are individually attached to body surfaces at the top and bottom, the front and rear, and the left and right, as shown inFIG. 8; the electrical potential gradient is formed in the biological subject by generating weak current flows between each pair of patch electrodes31; and position detection is performed based on the electrical potential recorded by electrodes provided in the endoscopes12(12aand12b) inserted into the biological subject.

With this type of endoscope-position detection system based on electrical impedance, there has been a problem in that position detection is difficult for the endoscope12inserted into the pericardium C in a state in which the surroundings of the endoscope12inserted into the pericardium C are filled with gas.

In this embodiment, an example will be described in which physiological electrolyte solution whose electrical conductivity is close to that of biological tissue is retained in the pericardium C, and position detection of the endoscope12is performed based on electrical impedance.

A known liquid, such as physiological saline solution, Ringer's solution, and so forth, can be used as the physiological electrolyte solution used in this embodiment.

In addition, a pump3which can be operated in forward/reverse directions is employed in this embodiment instead of the pumps1and2in the embodiment described above.

First, two sheaths11(for example, the Agilis steerable sheaths11made by St. Jude Medical Co. Ltd.) are indwelt in the pericardium C by accessing it from below the xiphoid process by using the method of Sosa et al. described above, and, subsequently, an endoscope12afor observing the interior of the pericardium C and an endoscope12bsuch as an ablation catheter or the like are individually inserted into the pericardium C via the sheaths11.

Routes (spaces) for the above-described two sheaths11that penetrate into the pericardium C are combined into a single liquid-feeding pathway at ends thereof on the stop-cock side of the respective three-way stop cocks (not shown) by means of a connector (flow-channel joining portion)30shown inFIG. 9. The combined liquid-feeding pathway is connected to the physiological-electrolyte-solution container8, in which the physiological electrolyte solution is temporarily stored, and the pump3.

The connector30is provided with a valve33that is opened at the time of an emergency and is also used as a pathway for replenishing the physiological electrolyte solution in the pericardium C by means of a syringe or the like via this valve33.

By combining the plurality of liquid-feeding pathways leading into the pericardium C by the connector30, even in the case in which the liquid-feeding resistance is different for the individual liquid-feeding pathways from the pericardium C, because adjustments are made so that a large amount of physiological electrolyte solution flows in a liquid-feeding pathway having a low liquid-feeding resistance, whereas only a small amount of physiological electrolyte solution flows in a liquid-feeding pathway having a large liquid-feeding resistance, efficient liquid feeding is possible.

As shown inFIG. 10, devices (the endoscopes12aand12bin this case) whose positions in the pericardium C need to be detected are provided with, for detecting the positions thereof, a pair of ring electrodes35aand35b, such as those provided in catheters for an electrophysiological examination.

The endoscopes12aand12bprovided with the above-described ring electrodes35aand35bare inserted into the pericardium C via the sheaths11.

The pump control device5controls injection/discharge of the physiological electrolyte solution by means of the pump3. An example of this control is shown inFIG. 11.

At the pump control device5, a trigger signal is generated under a trigger condition for capturing R-waves in the electrocardiogram, and a signal for injecting the physiological electrolyte solution into the pericardium C is output to the pump3after a certain period of time (Δt1) from the initiation of the trigger signal. At this time, for a time period Δt2, the signal is output while changing the liquid-feeding speed at the time of starting the injection and ending the injection, as shown by sloping portions of a graph of the liquid supply level/liquid discharge level versus time, shown inFIG. 11. Subsequently, for a time period Δt3, a signal for expelling the physiological electrolyte solution from the pericardium C is output to the pump3so that the pump3is operated while changing the discharging speed at the time of starting the discharge and ending the discharging, as with the case of injection.

Here, it is necessary to select the respective operating times so as to satisfy the relationship below:
RRinterval(ΔtR-R)>Δt1+Δt2+Δt3.

With the pericardial-liquid level control system103according to this embodiment, the amount of physiological electrolyte solution in the pericardium C can be stably controlled even if the RR interval (heart-beat movement interval) fluctuates within a range in which the above relationship is satisfied.

As with the first embodiment, also by determining non-response time Δti as below, a trigger-signal output due to noise can be reduced and the amount of physiological electrolyte solution can be stably controlled:
Δt1+Δt2+Δt3<Δti<ΔtR-R.

Here, by performing control so that the amount of physiological electrolyte solution supplied from the physiological-electrolyte-solution container by means of the pump3for the time period Δt2and the amount of physiological electrolyte solution discharged over the time period Δt3become equal, because there is no increase or decrease in the amount of physiological electrolyte solution in the pericardium C between heart beats, the amount of physiological electrolyte solution in the pericardium C can be stably controlled for an extended period of time.

In addition, because the liquid supplying/discharging speed is gradually changed, as compared with the on-off control described in the first embodiment, the liquid supplying/discharging resistance can be reduced at the time of starting up and shutting down, especially when switching between liquid supply and discharge, and thus, accurate liquid supply/discharge control is possible.

The physiological electrolyte solution may be added to the pericardium C via the valve33of the connector30shown inFIG. 9by means of a syringe or the like in the state in which the control of the amount of physiological electrolyte solution in the pericardium C is performed as described above, and the amount of physiological electrolyte solution to be supplied and the amount of physiological electrolyte solution to be discharged are controlled to be equal in accordance with the heart beat by means of the pump3. By doing so, the total amount of physiological electrolyte solution in the pericardium C can be adjusted while reducing the effects of the amount of physiological electrolyte solution in the pericardium C associated with the heart-beat movement.

In this embodiment, although descriptions have been given about a method in which the pump control device5controls the amount of physiological electrolyte solution in the pericardium C so that the liquid supply level and the liquid discharge level of the physiological electrolyte solution during heart beats are controlled to be equal, and the total amount of physiological electrolyte solution in the pericardium C is adjusted by the physiological electrolyte solution injected thereinto from the valve33of the connector30, the adjustment may be made by performing control so that “the liquid supply level of the physiological electrolyte solution>the liquid discharge level of the physiological electrolyte solution” is achieved during heart beats when the total amount of physiological electrolyte solution in the pericardium C needs to be increased and so that “the liquid supply level of the physiological electrolyte solution<the liquid discharge level of the physiological electrolyte solution” is achieved during heat beats when the total amount of physiological electrolyte solution in the pericardium C needs to be reduced.

In addition, although an example was described in this embodiment in which the amount of physiological electrolyte solution is controlled by using gaps between the two sheaths11and the individual endoscopes12aand12binserted thereinto as pathways to do so, the number of sheaths11is not limited to two, and a greater number of sheaths11may be combined into a single liquid supply/discharge pathway, or, in the case in which the endoscope12that is inserted into the sheath11is provided with liquid feeding/discharging pathways, those liquid feeding/discharging pathways may also be combined.

Furthermore, although an example is shown inFIG. 8in which electrocardiogram electrodes7aand7battached to the patient are connected to the electrocardiograph and the measured electrocardiogram is input to the pump control device5, the signals measured between the patch electrodes31for forming the graduated electrical potential for position detection may be used as substitutes for the electrocardiogram.

Although the individual embodiments of the present invention have been described in detail with reference to the drawings, specific configurations are not limited to these embodiments, and design alterations are also encompassed within a range that does not depart from the spirit of the present invention. For example, the present invention may be employed in an embodiment in which the individual embodiments described above are appropriately combined.

According to the above embodiments, following aspects can be introduced.

An aspect of the present invention employs a pericardial-liquid level control system including a pipe that is inserted into a pericardium; a pump that supplies and expels liquid to and from the pipe; an electrocardiographic-information detecting portion that detects electrocardiographic information; and a controlling portion that, in synchronization with the electrocardiographic information detected by the electrocardiographic-information detecting portion, controls the pump so that the liquid is supplied to the pericardium via the pipe during contraction of the heart and the liquid is expelled from the pericardium via the pipe during expansion of the heart.

With the aspect of the invention, in the state in which the pipe is inserted into the pericardium, the electrocardiographic information is detected by the electrocardiographic-information detecting portion, and the operation of the pump is controlled by the controlling portion in synchronization with the electrocardiographic information. Specifically, the pump is controlled so that the liquid is supplied into the pericardium via the pipe during contraction of the heart and the liquid is expelled from the pericardium via the pipe during expansion of the heart.

By injecting/expelling the liquid into and from the pericardium in synchronization with the electrocardiographic information as described above, the heart can sufficiently be expanded during expansion of the heart while retaining the liquid in the pericardium by removing the liquid in the pericardium that reduces the expansion of the heart. By doing so, it is possible to prevent so-called cardiac tamponade in which the pulsing of the heart is impeded by the liquid retained in the pericardium.

In addition, by retaining the liquid in the pericardium, drying of the epicardium can be prevented and a sufficient viewing field can also be ensured for an endoscope inserted into the pericardium by expanding the interior of the pericardium by means of the liquid. In addition, the liquid retained in the pericardium can also be utilized as an acoustic medium for an ultrasonic device inserted into the pericardium or as a cooling medium for an ablation device inserted into the pericardium. Furthermore, it is also possible to lift the heart in the pericardium with a low force due to the buoyancy of the liquid in the pericardium, and thus the back wall of the heart can be more easily accessed.

The above-described invention may be provided with a flow-channel joining portion that combines a supplying channel for supplying the liquid to the pericardium and an expelling channel for expelling the liquid from the pericardium into a single flow channel.

By providing such a flow-channel joining portion, the supplying channel for supplying the liquid into the pericardium and the expelling channel for expelling the liquid from the pericardium can be connected together to the pipe at the body exterior. By doing so, the operation for feeding the liquid into the pericardium can be simplified by reducing the number of the liquid-feeding routes (for example, tubes).

In the above-described invention, a plurality of the pumps may be provided; and the supplying channel for supplying the liquid to the pericardium and the expelling channel for expelling the liquid from the pericardium may be connected to separate pumps.

By employing such a configuration, the supplying channel for supplying the liquid into the pericardium and the expelling channel for expelling the liquid from the pericardium can be provided as separate routes. By doing so, it is possible to maintain high clearness of the liquid in the pericardium by supplying fresh liquid to the pericardium from the supplying channel, and it is possible to obtain a clear image of the interior of the pericardium by means of an endoscope or the like.

The above-described invention may be provided with an electrocardiogram generating portion that generates an electrocardiogram from the electrocardiographic information detected by the electrocardiographic-information detecting portion; and an R-wave detecting portion that detects an R-wave from the electrocardiogram generated by the electrocardiogram generating portion, wherein the controlling portion causes the pump to operate after a predetermined period of time has elapsed since the time when the R-wave is detected by the R-wave detecting portion.

By employing such a configuration, periods of contraction and expansion of the heart can be ascertained accurately by detecting the R waves from the electrocardiogram by means of the R-wave detecting portion, and the liquid can be injected into and expelled from the pericardium by operating the pump in accordance with that timing. By doing so, cardiac tamponade can reliably be prevented.

In the above-described invention, the controlling portion may cause the pump to operate so that the amount of liquid supplied to the pericardium and the amount of liquid expelled from the pericardium become substantially equal.

By doing so, it is possible to keep the interior of the pericardium at a substantially constant pressure, and it is possible to reduce damage to the heart and the pericardial membrane due to pressure fluctuations of the liquid in the pericardium. In addition, because there is no increase or decrease in the amount of liquid in the pericardium between heart beats, the amount of liquid in the pericardium can stably be controlled for an extended period of time.

In the above-described invention, the controlling portion may control the pump so that a liquid-feeding speed is gradually increased when the liquid supply to the pericardium is started and the liquid-feeding speed is gradually decreased before the liquid supply to the pericardium ends.

By doing so, the liquid-supplying resistance can be reduced at the time of starting up the operation of the pump and shutting down the operation thereof, especially when switching between liquid supply and liquid discharge, and thus, accurate liquid-supply control is possible.

In the above-described invention, the controlling portion may control the pump so that a liquid-feeding speed is gradually increased when the liquid expelling from the pericardium is started and the liquid-feeding speed is gradually decreased before the liquid expelling from the pericardium ends.

By doing so, the liquid-discharging resistance can be reduced at the time of starting up the operation of the pump and shutting down the operation thereof, especially when switching between liquid supply and liquid discharge, and thus, accurate liquid-discharge control is possible.

In the above-described invention, the controlling portion may control the pump so that the amount of change in the liquid-feeding speed of the pump becomes constant.

By doing so, it is possible to eliminate an increase in the liquid-feeding resistance when the liquid-feeding speed abruptly changes, which makes it possible to reduce the burden on the pump and also to perform stable liquid-feeding control.

A pericardial-liquid level control method comprising:

inserting a pipe into the pericardium and detecting electrocardiographic information; and,

in synchronization with the detected electrocardiographic information, supplying liquid into the pericardium via the pipe during contraction of the heart and also expelling the liquid from the pericardium via the pipe during expansion of the heart.

A pericardial-liquid level control method according to Additional Item 1, wherein

an electrocardiogram is generated from the electrocardiographic information, and an R-wave is also detected from the electrocardiogram; and

the liquid is supplied into or expelled from the pericardium after a predetermined amount of time has elapsed since the time of the R-wave detection.

A pericardial-liquid level control method according to Additional Item 1, wherein the liquid is supplied to or expelled from the pericardium so that the amount of liquid supplied to the pericardium and the amount of liquid expelled from the pericardium become substantially equal.

A pericardial-liquid level control method according to Additional Item 1, wherein the liquid is supplied to the pericardium by gradually increasing the liquid-feeding speed when the liquid supply to the pericardium is started and by gradually decreasing the liquid-feeding speed before the liquid supply to the pericardium ends.

A pericardial-liquid level control method according to Additional Item 1, wherein the liquid is expelled from the pericardium by gradually increasing the liquid-feeding speed when the liquid expelling from the pericardium is started and by gradually decreasing the liquid-feeding speed before the liquid expelling from the pericardium ends.

A pericardial-liquid level control method according to Additional Item 4 or 5, wherein the liquid is supplied to or expelled from the pericardium so that the amount of change in the liquid-feeding speed for the pericardium is constant.

REFERENCE SIGNS LIST