Gravitation-Controlled Heart Perfusion Systems

For The Langendorff Examination Of Small Mammal Hearts With Working Heart Option

Specifications

Features

System Overview

The advantage of the gravitational product line is that the constant pressure – by the continuous replacement of the saline – can be sustained in a stable way. Another key advantage is that by inserting a proper peristaltic pump, the constant flow mode can be easily configured. The systems are produced in one- and two-channel designs (LS-01G, LS-02G) including the Janicki-type working heart option, by default. Any basic model can be upgraded with the Neely-type working heart option (LF-03GN) without buying any further device. A further key advantage is that the system is supplied with a self-supporting table, which allows an easy placement in the laboratory.

The devices are suitable for isolated mouse, rat, guinea pig and rabbit heart examination
The temperature stability of the system is within 0,1ºC, measured directly at the heart connection
The easy placement of the preparation to the heart suspender is provided by the special design of mobile heart suspending unit and the heart suspending cannula, which both fit to species
The advantage of gravitational design is that the constant flow and constant pressure mode can be simultaneously achieved
The pressure meter sensors and the drug injection inlet are located directly next to the heart
The systems include the Janicki-type working heart measuring option, by default
Provides an opportunity to stimulate the attached dissection (pacing)
The extra-/intracellular MAP measurement is resolved in the systems
Sizes: width: 800 mm, depth: 600 mm, height: 2250 mm

One and Two Column Langendorff Systems

The flowchart of the two-column system (LS-02G) illustrates the operating principle, which is identical with the one-column system (LS-01G). The advantage of the LS-02G is that two material impacts can be examined on the preparation simultaneously.

Langedorff Heart Suspending Unit and Cannula

We tried to develop a heart suspending unit, where the preparation can be placed on cannula quickly and without damage. The end of the cannula is notched, which supports the method of placement and the positioning of the binding thread.

Taking the weight into consideration, the cannula is available in the following sizes: Ø4.5, Ø3.0, Ø2.0 and Ø0.9 mm. One of its biggest advantage is that the measuring points and the material administration are directly above the preparation, which makes dead space minimal.

The optimal temperature (within 0,1oC) is provided by the temperature measurement above the preparation and the autonomous liquid circulation above the heart suspending unit.

LS-03GN Neely-Type Working Heart Option

The biggest advantage of the new system is that – unlike any other system on the market- no new device is necessary, even if you wish to expand the methodological background with the Neely option.
If you have any pump-controlled Langendorff system (LS-01G, LS-02G) you only need to purchase the Neely option and the heart suspending unit for the methodology

Langedorff-Neely Heart Suspending Unit and Cannula

The Neely option has all the advantages, which we highlighted at the Langendorff heart chamber. A further advantage is the specially designed arrangement of the cannulas, which allows the simultaneous placement of the cannulas into the aorta and the left atrium. Taking the weight into consideration, the cannulas are available in the following sizes: Ø4.5, Ø3.0, Ø2.0 mm.

Extra-/Intracellular MAP Measurement, Stimulation

The system allows one-point extra-/intracellular MAP measurement and stimulation, built in a 360o adjustable ball manipulator. The manipulator can be organically connected to the system.

Eight-Point Extracellular MAP Measurement

The eight-point non-invasive measurement is a unique development of our company. The preparation is placed in an organ bath filled with saline soultion, surrounded by the MAP sensor. The sensors detect the MAP signals through the solution, which are detected by a specially designed biological amplifier.

Saline Solution Managing Taps

The taps are essential parts of the system, which lead the saline to the preparation. For this purpose we designed a multi-position, high-quality and long-wearing tap. The essence of the construction is that the material combination of the tap allows appropriate grip surface, gapless sealing, and allows smooth closing/opening movement. Moreover, contrary to other systems’ taps, it does not have two positions (open/close), but it closes continuously.

Gas Vaporization

For the appropriate operation of the heart, appropriate quantity and quality carbogen gas is necessary being dissolved in the saline solution. For the necessary dispersion, we developed a gas vaporizer and fine-tuning device. The gas flowing through the redactor of the bottle is collected in a windbag, and through a cylindrical clamp – a tube with appropriate wall thickness – the carbogen gas is vaporized into the solution.

The System

We deliver the system in a complete setup, which contains all the sensors and amplifiers necessary for pressure measurement and the measurement of MAP signals and the programmable isolator square-wave generator for the stimulation of the preparation. We provide two measurement station for reliable and easy management: 1. Haemodynamic setup with one-point extra-/intracellular MAP measurement:

2pcs pressure measurer with sensors

1pc biological amplifier with sensor

1pc temperature measurer with sensor

2. Eight-point extracellular MAP measurement:

1pc eight-channel biological amplifier

We recommend the following softwares for the visualization, storage and analysis of the curves, which represent the measured physiological parameters:

SPEL HAEMOSYS (MDE GmbH)

LabChart (ADInstruments)

AcqKnowledge (BIOPAC)

Specifications

	Buffer Columns
	Diameter: 56mm; Height: 1154mm Double-walled, thermostated borosilicate glass vessel Fixed fluid level adjuster with threaded bottom and glass tube Adjustable carbonizer with vaporizer

	Heart Chamber
	Diameter: 80mm Height: 185mm Material: Borosilicate glass
	Diameter: 80mm Height: 185mm Material: Borosilicate glass

	Buffer Drain Reservoir
	Diameter: 56mm Height: 160mm In the thermostating space with two independently built-in spirals

	Taps
	1 pc two-way filling tap/buffer column 1 pc three-way drain tap Material: Plexi body with Teflon inlay

	Langendorff Frame
	The frame stands on a table, the top of which is made of stainless steel The table top has a low edge drip tray and drain pipe Size of the table top 800mm x 600mm Height of the table top (from the ground): 750mm Height of the complete frame (from the ground): 2500 mm Weight of the frame depending on the configuration (without load): ~60 kg

Features & Benefits

Types of the Systems

Systems developed by MDE GmbH provide a wide range for in-vitro heart examination. Systems can be used for experiments on any laboratory animal without significant alterations. Heart Perfusion Systems can be classified the following way:

Based on physical features:

Gravitational (classic design)

Pump-controlled

Based on methodological features:

Constant pressure and/or flow
Working heart:
- Janicki-type (balloon)
- Neely-type (retrograde flow)

The Essence of the Methodology

Before presenting the technical solution and the unique operation of each device, we represent the essence of the methodology with a brief historical overview.

In case of the standard Langendorff heart the coronary circulator system is perfunded. The empty left ventricle contracts, but it does not pump any liquid. The preparation can be easily altered by installing a second perfusion circle, so the left ventricle can perform pressure work. These type of experiments were first documented by Ridler in 1932, and then by Heubner and Mancke in 1935. The detailed description was published by Neely in 1967. The following picture presents a simple theoretical drawing of the device.

Image 1: Simple Theoretical Drawing of the Device

This simple solution was schematically resolved by the Bardenheuer and Schrader variation (1983), where they lead a balloon into the left ventricle. They do not measure the isovolumetric pressure, instead it pumps the liquid from the balloon into a closed extracorporeal system. Because of the two non-return valves, the liquid can only flow in one direction.

Upon every stroke the content of the balloon is squeezed out, which is identical with the stroke volume of the heart. Preload and afterload can be adjusted separately. The flow of the completely separated saline (retrograde in the aorta through the coronaries) is registered quantitatively. In this way the biochemical and biophysical circulation of the system can be separately analyzed. This preparation can be useful to examine the pressure-volume work of the heart and the biochemical parameters of the saline in the coronary (e.g.: O2 consumption, metabolism).

A modified Langendorff (Janicki et al. (1974,) Weber and Janicki (1978)) is used for simple hemodynamic-biophysical observations (e.g.: relations of the ventricle pressure-volume), which is similarly to previous descriptions utilizes balloon and separated circulation to maintain the coronary perfusion and pressure. In this case the pressure meter is connected to the balloon. The volume of the balloon is measured and regulated through re-attachable electronics by the sensor.

Image 2: Bardenheuer and Schrader Variation

Advantages of Different Systems

Gravitational Systems (LS-01G, LS-02G, LS-03GN)

The systems are manufactured in one- and two-buffer designs. The constant pressure necessary for the operation of the dissection (mouse, rat, guinea pig or rabbit heart) are provided by the liquid column located in the reservoir. The advantage of the two-column design is that is can be used to examine the effects of the same compound in different doses or the effects of two different compounds successively. The liquid level is ensured by the overflow stub of the reservoir and the pump-controlled recirculation of the liquids leaving the dissection. Density and viscosity are provided by the material-combination of the flow-controlling taps, which make any other sealing-compound unnecessary. The design allows a quick and calibrated correction of wearings resulted from the use of the taps. The warmth of the system (0,1OC) is ensured by a high-flow rate transporting, 20 liters volume thermostat (CWB-02). The positioning of the dissection is provided by an independent mechanism (heart suspension), which is connected to the liquid reservoir through the taps and the spiral heat exchanger. Upon the design of the heart suspender, a primary aspect was that the sensors of the continuously monitored parameters (e.g.: pressure, temperature) should be placed next to the heart.

We can offer two solutions for the examination of the working heart:

Janicki-type (balloon), which is contained in the basic system setup
Neely-type (retrograde flow), which can be optionally connected to the Langendorff system

Pump-Controlled Systems (LS-04P, LS-05P, LS-06-PN)

The pump-controlled systems have all the positive characteristics that we have mentioned in connection with the gravitational systems. Other advantages over those systems are that they require small space and the same device (pump) can be used for constant pressure and flow. The retrofication of certain components of the gravitational systems resulted in the reduced size of the pump-controlled systems, which increased the stability of liquid-flow, while reducing the consumption of the saline and the examined compound. Pump-controlled systems are easier to repair and clean.

Compact Pump-Controlled System (LS-07C)

The compact pump-controlled heart-perfusion system is a closed, integrated system, placed in a water-circulation self-thermostated fluid tank. The tank contains two saline holding reservoirs, an organ chamber for the heart dissection and a specially designed, removable heart suspending unit. The water bath solution completely isolates the system from the ambient temperature. The system guarantees a 0,01OC accuracy, which provides an extremely stable environment for the dissection. Another advantage is the removable heart suspending unit, which provides the most optimal suspension solution for laboratory animal hearts. The accuracy is increased by the fact that the measuring points (BP, temperature, etc.) together with the material inlet channel are placed directly by the stump of the organ suspender. With the minimal space requirement, the system is suitable to perform constant pressure and flow, or Janicki-type working heart modes. The quantitative consumption of the saline and the examined agent highly prevails, since shorter internal phases reduce the path of the agent to the examined organ. Further elements (taps, gas vaporizers) have a similar solution to open system. These characteristics make the system completely unique compared to any other systems on the market.

Electrophysiological Measurement Options

To detect the extra- and intracellular MAP sign, we developed constructions, which can be easily adapted to the systems. The electrodes can be easily connected to the mechanical surface of the systems, even posteriorly, and provide a possibility to arrange surface or intracavitary measurements.

The eight-point non-invasive extracellular MAP measurement is a unique solution, where the heart in the organ chamber is surrounded by saline. The heart is positioned by the specially designed chamber, which eliminates the negative effects of buoyancy.

Further advantage of intra-liquid measurement is that tissue edema can be reduced, since the colloid osmotic pressure is balanced by the hydrostatic pressure of the container. This prolongs the life expectancy of the dissection. Furthermore, chamber extrasystole can be created by pulse impulses, helping the examination of different anti-arrhythmic agent effects.

Available Models

LS-01G: One-Column Isolated Heart Perfusion System (Constant Flow/Pressure)


LF-11	One-column Langendorff frame, glass tanks and silicone tubing Buffer column with tap Heart suspending unit with isolated chamber (for details see LF-10-K01 datasheet) LVP balloon pressure sensor (Janicki type)
EXP-TH-1	Temperature meter amplifier (1-channel)
SEN-07-12	Temperature meter sensor Roller pump

LS-03GN: Neely-Type Isolated Heart Perfusion System


LF-11	One-column Langendorff frame, glass tanks and silicone tubing Buffer column with tap Heart suspending unit with isolated chamber (for details see LF-10-K01 datasheet) LVP balloon pressure sensor (Janicki type)
EXP-TH-1	Temperature meter amplifier (1-channel)
SEN-07-12	Temperature meter sensor Roller pump

LS-03GN: Neely-Type Isolated Heart Perfusion System


LF-11	One-column Langendorff frame, glass tanks and silicone tubing Buffer column with tap Heart suspending unit with isolated chamber (for details see LF-10-K01 datasheet) LVP balloon pressure sensor (Janicki type) Precise peristaltic pump (min. eight rollers)
EXP-TH-1	Temperature meter amplifier (1-channel)
SEN-07-12	Temperature meter sensor Roller pump

Optional Additions for All Models * You only need to purchase one (1) of the data acquisition systems
EXP-HG-2	DC bridge amplifier (2-channel) for invasive blood pressure measurements
SEN-02	Invasive blood pressure sensor
EXP-EXT-1	Broadband amplifier (1-channel) for intra-/extracellular MAP measurements
SEN-26	Intracellular MAP sensor with ball-mounted manipulator (360° movement, self-righting)
EXP-EXT-4	Broadband amplifier (4-channel)
SEN-13-0X	Extracellular MAP sensor (for details see SEN-13-K01 datasheet)
EXP-ST-01	One-channel non-isolated stimulator (10 / 100V / 50mA) with built-in MCU controlling unit
SEN-12-12	Ball-mounted manipulator (360° movement, self-righting) with platinum stimulating electrode
CWB-02	Circulating water bath (20 litres, 20 l/min delivery speed, ±0,1°C)
LF-10-85	Heart muscle contraction measuring unit: DC bridge amplifier with force transducer (SEN-03-34), mounting structure and one-plane manipulator Flow meter with in-line probe Precise peristaltic pump Balloon for LVP pressure measurement (10pc/pack)
SOFT-01	MDE – SPEL HAEMOSYS Monitoring, measuring and analysing software system with accessories*
ADI-PL	ADInstruments PowerLab with LabChart PRO software*
iWorx-LBS	iWorx – LabScribe software*
iWorx-LBS	iWorx – LabScribe software*
Biopac-Acq	BIOPAC – AcqKnowledge*