CardioFish

Precision Instruments for Biological Research

System Overview

Specifications

Videos

How Can it Help?

System Overview

The CARDIOFISH system is the latest development of the MDE GmbH, which provides an opportunity to examine heart function of the adult zebrafish. The system can be effectively used to examine the effects and side-effects of candidate medicine molecules in pharmacology, safety pharmacology and toxicology. It is also well suited to basic research on arrhythmias and regeneration abilities of the heart muscle.

Available Models: ZFS-01: CardioFish Heart Electrophysiological Measurement System

Components:

1 pc Base plate with Faraday cage
1 pc Measuring block: subject table with vertical / horizontal adjustment mechanics
2 pcs 50µm one-plane manipulator with built in electrode vessel
1 pc Fish tank with liquid input cannula and inlet for drug administration
2 pcs Buffer reservoirs with gas vaporizer
1 pc Broadband AC measuring amplifier
1 pc Liquid delivering peristaltic pump with reversing taps and vibration damping chamber
1 pc CardioFish Z-01 measuring, analyzing and storing hardware/software system

Measuring System

The CardioFish system, was developed for a detailed electrophysiological examination of the zebra fish hearth, and includes three main units:

Mechanical unit
Low-noise broadband analogue amplifier
Data visualization, – archiving and –evaluation hardware/software

While designing the system, we focused on its ability to be easily transported, assembled and operated. On the grounds of this, a workstation was created, with high learnability and usability.

The vibration-free object table is holding the two main units of the system (the micromanipulators and the broadband amplifier). The Faraday cage encloses this ensemble and carries the broadband amplifier on its backside. It ensures complete shielding from electrical and magnetic fields interference. Attached to the table are the fish tub and the two micromanipulators. The micromanipulators can easily be adjusted horizontally and bear removable electrode-holders that can accept either our stainless-steel premanufactured electrodes, or user-designed electrodes or a standard holder for glass electrodes.

Measuring Database

The acquisition and analysis framework is derived from our well validated recording and analysis system (Cardiosys), used for 15 years in cardiac R&D. The data recording and processing system is built around the Cardiofish Z-01 software, which has an inbuilt database architecture, where all the measurement results are automatically stored. The database can be opened with a quickbutton, or with the appropriate option of the main menu.

The measurement results are placed under the measurement entity, while measurement entities can be arranged into groups.
The panel makes it possible to record data of new entity or to select a previously recorded group for new measurements. Previous measurement files can be opened again at any time, verified ad re-evaluated with any of the data processing functions.

ECG Recording

For ECG recordings both the quickbuttons above the monitoring filed and the roll down orders of the menu can be applied. The applied filter visualization or the appearing visual parameters of the ECG curve can be altered (eg.: amplification, speed), the notes belonging to the measurements can be recorded, respectively the recording process can be started or stopped.

Signal display can be adjusted by setting the width of the time window and amplification display factor. The optimisation of filter effects (50 or 60 Hz notch filter, high-pass baseline filter (removing breath-related baseline oscillations) and low-pass high frequency rejection filter) is aided by visualizing superimposed raw and filtered signals. User can place time labels with comments along the recording session, making it easier to retrieve sections of interest for off-line analysis.

Offline Evaluation

The recorded ECG signal can be either evaluated right after the measurements or at any time later. The software provides five different possibilities for so doing. The most typical ECG parameters can be quickly calculated, as well as more complex features however, owing to the wide choice of analysis routines included.

1. One Cursor Analysis: can be applied to collect the amplitudes, at user defined cursor position on the ECG signal, and HR values are collected into a chart.

2. ECG Normal Analysis: evaluating the ECG with automatic parameter measurements, from any single optional cycle chosen by the user.

3. ECG Averaged Analysis: A user defined number of continues ECG cycles can be synchronized and averaged, allowing extraction of low amplitude features. Automatic parameter measurements can be done on any user defined time region of the averaged signal.

4. ECG QT Analysis: calculating an eligible QT or QTc value, as well as QT variability (QTv) as a function of RR or HR, in case of at least 32 chosen cycles.

5. Heart Rate Variability (HRV) Analysis: The analysis of the variation of heart frequency with time and frequency domain analysis, RR normalization is also provided

Specifications

Electronic Specifications


Programmes run on Windows-based 64 bit operating system	Muscle movement (vibration, tremor) filtering algorithm
Making single-channel recording	Sampling frequency: 1000 samples/sec/channel
Visualizing and recording real-time curve	Amplification: 10000x
Screen running time: 5, 10, 25 or 50 mm/sec	Input resistance: 10 MΩ symmetric
Persistent ECG monitoring with heart frequency display	Output resistance: 50 Ω
A.C. network noise-filtering algorithm (50/60Hz notch filter)	Output Voltage Range: ±5V 2kHz

Mechanical Parameters


Overall dimension: 400x300x350 mm	Overall dimensions of fish bath: 90x40x20 mm
Manipulators 0,05 mm /revolution/25 mm course	Material of fish bath: anodized aluminium
Size of fish bath: 20 ml

How Can it Help?

The CardioFish measuring system, a highly integrated workstation, designed and developed by our company is suitable for the measurement of spontaneous or affected cardiac responses on adult (at least 3 months old) species. The mechanics, the sensor the low-noise broadband amplifier and the data displaying, storaging and analyzing software form a harmonious unit in the system.

The design of the measuring unit was based on the fact that ion channels defining the operation of the heart show partial similarity between human and zebrafish. This mechanism results in a nearly similar monophasic potential (MAP) measurement to the human ECG.

Zebrafish Heart / Human Heart Comparison

Commonalities

Heart rate
Connection between QT and heart rate
The shape of the action potential (MAP): the Na wave/power is liable for fast depolarization, L-type Ca channel is liable for the long plateau phase and IKr plays a role in repolarization
There is an acetylcholine-activated K (KAch) channel
Pharmaceuticals, which lengthen the QT phase in human therapy also result in a lengthened QT phase in case of zebra danios (this feature is a characteristic of adults and embryos as well)
In case of KCNH2 (IKr channel) mutation the action potential of the heterozygote fish lengthens, while in case of wild species, a small concentration of dofetilide does not result in any significant change

Differences

How Does The System Work?

When designing the system a fundamental requirement was to ensure the stability of parameters of animal physiology and the objectivity of measurement.

The following picture represents the operation of the system:

The liquid enriched with gas goes through the G1 and G2 buffer tank through switch tap A, roller pump B, elastic vessel C, bubble remover chamber D and cannula E1 before reaching the laboratory animal.
The laboratory animal is placed on a sponge foam in bath E, which also keeps the body continuously wet. The excess liquid returns to tank G through the outlet and switch tap F.
The gas supply of the tanks is provided through valve J1 and J2.

How Does The System Work?

One of the strengths of the system is the possibility of electrode positioning, which is ensured by the flexibly adjustable mechanics, the manipulators, which can be positioned in any level of the space and a vertically adjustable object table.

Manipulator Positioning:
The manipulators are in the centre of the measuring block, with which the stainless steel electrodes can be inserted into the examined laboratory animal. The manipulator sting can be finely adjusted not just on the X (stabbing) plane, but also on Y and Z axis. The Y (electrode applicator) plane movement helps to apply the electrodes in the electrode sleeve, where the ball joint design allows free circular movement. The free Z (positioning) plane movement helps to apply the optimal stabbing position. (image 1)

Measuring Block Positioning:
The block can be vertically moved on the rods fixed to the table. The position can be stabilized with the lever located on the left hand-side. The large scale adjustment of the measuring block facilitates cleaning, the placement of the species in the bath, the electrode replacement or the settings when applying a longer electrode. (image 2)

Electrode Connection:
The electrodes can be connected to the system when the manipulators are unfolded. After connection the electrode vessel can be fixed with its purpose-made hollander. This allows the use of any other type of electrode, as long as this information is available when the device is manufactured. (image 3)

Further Possibilities of Application

Drug Injection:

The E1 cannula connection allows direct drug injection into the gas-enriched liquid, which is lead to the experimental subject.
External drug injection units can also be used (e.g.: MAN-07 precision manipulator, WPI Nanoliter 2010 pump, etc.) which help to inject the drug into body cavities or tissues.

Intracellular Measuring Option:

The mechanical design of the systems (e.g.: vibration-free adjustable object table, special manipulators, variable electrode sleeve, etc.) allows intracellular measurements in the zebra danio embrio. We provide the amplifier (EXP-INT-1), electrostimulator (EXP-ST-A1), and electrode sleeve (WPI MEH micropipette), which are necessary for the measurement.

Methodological Assistance

An integral part of our company philosophy is to continuously follow-up the sold products, provide fast service and methodological trainings. Trainings can be organized in the following conference places:

Institute	Location	User
INSERM, EA 4612 Neurocardiology, Physiopathology of the disorders of the heart rhythm	Lyon, FRANCE	Georges Christé, PhD
Szent Istvan University, Department of Aquaculture	Gödöllő, HUNGARY	Béla Urbányi, PhD