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Working Heart |
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| ADInstruments provide complete and easy-to-use systems for isolated working heart research. |
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The first method of perfusing isolated hearts was introduced by Oscar Langendorff, which uses a retrograde perfusion. A second method of perfusing isolated hearts, was developed by Neely et al in the 1960’s. This is known as the ‘working heart’ method. This method allows the heart to pump fluid via the normal left ventricular circulatory pathway as the perfusate enters the heart via the cannulated left atrium, passes through to the left ventricle and is ejected out of the aorta. Commonly with the working heart method, the atrial pressure (preload) and aortic resistance (afterload) are regulated experimentally as the heart circulates the perfusate solution. The aortic and coronary flows can also be monitored and the resulting cardiac output calculated.
For adequate perfusion of the heart a suitably sized cannula for insertion into the aorta is provided. Initially the heart is perfused in the Langendorff mode. Then a second cannula is inserted into the pulmonary vein to perfuse the left atrium. After successful cannulation of pulmonary vein, the perfusion is switched to the working heart mode. There are then a number of parameters that can be measured from the working heart preparation. Left Atrial (Preload) PressureThe left atrial or preload pressure can be monitored in the working heart set-up by attaching a physiological pressure transducer to the perfusate line entering the left atrium.Aortic (Afterload) PressureThe Aortic or afterload pressure can be monitored in the working heart set-up by attaching a physiological pressure transducer to the perfusate line exiting the aorta.Contractile ForceA simple method that can be used to measure the contractile force of the heart, is to connect the apex of the heart to a force transducer and bridge amp via a pulley system. Tension is applied to the thread attaching the heart to the transducer and changes in contractile force can be monitored. Electrical ActivityThe cardiac electrical activity of a Langendorff preparation can be measured using a bioamplifier and suitable electrodes. Typically, one electrode is connected to the apex of the heart and one to the atria. The ground electrode can be connected to the aortic cannula. Alternatively, with a suitable electrode, monophasic action potentials can be measured form single cardiac cells.TemperatureIt is important that a stable temperature is maintained in the isolated heart. The temperature can be measured with a t-type temperature probe and pod. The probe can be inserted into the perfusate flow or into the heart.PacingThe heart may be paced using an external stimulator with a stimulus that exceeds the natural cardiac pacemaker rate, after the sinoatrial node is crushed or the right atrium excised. Pacing voltage is determined as a set percentage (normally 110-150%) above the voltage required to capture (pace) the heart and usually should not have to exceed 3-5V with a duration of 0.1 to 1 msec. The PowerLab data acquisition system has an analog output in conjuction with the Stimulator panel in LabChart, can be used to control the frequency of the stimulator pulses.Left Ventricular Pressure/VolumeAs the working heart is a closed system, with the perfusate following the normal left sided circuitory, simultaneous left-ventricular pressure and volume measurements can be made using a Millar Pressure Volume catheter and control unit. Further heamodynamic measurements can be made from the resulting Pressure-Volume loops. More details regarding PV measurements can be found on the Ventricular Pressure-Volume application pages.Atrial, Aortic and Coronary FlowBy inserting a suitable flow probe into the perfusate lines going into the left atrium and out of the aorta, the atrial and aortic flow rates can be determined. By subtracting the aortic flow from the atrial inflow, you can calculate the resultant coronary flow. Alternatively, the coronary flow can be determined by collecting the coronary effluent over a known time period. pH & O2 concentrationIt is important to maintain the correct pH and a suitable oxygen concentration of the perfusate solution. These can be measured if required using a suitable pH electrode and pH amplifier and a suitable dip type or flow through oxygen electrode. To measure the oxygen consumption, O 2 electrodes can be placed in the inflow and in the effluent and the difference in concentration calculated.
LabChartLabChart software (for Windows and Macintosh) combines the familiar simplicity of a traditional strip chart recorder with the powerful analysis features of a digital acquisition system. LabChart software and a PowerLab data acquisition unit provide data integrity, easy selection of hardware settings, powerful online and offline analysis, procedure automation, seamless extraction of experimental data and flexible display options. Acquisition and analysis capabilities can be further increased with LabChart Extensions and LabChart Modules. LabChart Modules are available as part of LabChart Pro and LabChart Extensions are free for download from the website for existing LabChart users. Using LabChart, the following raw inputs can be made from a Working Heart experiment using the standard equipment: - Atrial (Preload) Pressure
- Aortic (Afterload) Pressure
- ECG
- Temperature
The following calculated measurements can be made using LabChart functionality: - Heart Rate (cyclic rate of Aortic Pressure)
- Left Ventricular Systolic & Diastolic Pressure (cyclic Maximum and Minimum of LVP)
- dV/dT Atrial Pressure (1st derivative Atrial Pressure)
- dV/dT Aortic Pressure (1st derivative Aortic Pressure)
Additional measurements that can be made with the ultimate working heart systems include: - Left Ventricular Pressure and Volume
- Atrial Flow Rate
- Aortic Flow Rate
- Coronary Flow rate (Atrial Flow-Aortic Flow)
- Cardiac Output
- pH
- Oxygen concentration or consumption
LabChart Extensions include: - Cardiac Axis LabChart Extension: Automate thecalculation of frontal plane ECGs and vector cardiograms and display ofthe instantaneous cardiac vector.
- SAECG(signal averaged ECG) LabChart Extension (MAC only): Calculates theaverage cycle of ECG signals and automatically identifies specificationwaveforms and cardiac indices.
- PeakParameters LabChart Extension: Determines a number of parameters for anindividual peak and is ideal for analyzing cardiac action potentials.
Blood Pressure Module (Windows)The MLS370/6 Blood Pressure Module for Windows automatically detects, analyzes and reports cardiovascular parameters from arterial or ventricular pressure signals. The settings dialog allows the user to select ventricular pressure for analysis and the Classifier View allows for easy selection of pressure waveforms for further analyses. Pressure cycles that are contaminated by artifact, have abnormal cycle heights or cycle durations (frequency) can be excluded from analysis using the classifier. The Analysis View displays pressure cycles as beat-by-beat or as the average of a specified number of cycles. Ventricular parameters such as EDP, Max dP/dt, Min dP/dt, Min and Max Pressure are labeled. These measurements along with other calculated parameters are logged in the Table View for easy exporting. Features and benefits include: - Suitable for analysis of pressure signals from humans as well as large and small animals
- Pressure signals can be analyzed in real time during acquisition
- The BP Classifier makes detection and exclusion of atypical waveforms easy
- Parameters can be displayed as continuous data on separate channels
- Values are logged to the Table View
- Averages any number of pressure waveforms
Calculated arterial parameters include: - Systolic, Diastolic and Mean Pressure
- Pulse Pressure
- Dichrotic Notch Pressure
- Ejection and Non-ejection duration
- Cycle Duration
- Heart Rate
Calculated ventricular parameters include: - Maximum Pressure
- Maximum dP/dt
- Isovolumic Relaxation
- Minimum Pressure
- Minimum dP/dt
- Mean Pressure
- End Diastolic Pressure (EDP)
- Maximum-Minimum Pressure
- Contractility Index
ECG Analysis Module (Windows)The MLS360/6 ECG Analysis Module provides a comprehens ive set of tools that automatically detects and reports values of ECG recordings. The software can be used with ECG recordings taken from humans and many species of animals from pigs through to mice.
It provides
- Real-time analysis and data extraction of ECG parameters
- PQRST amplitudes
- Time intervals such as RR, PR, JT, QT and QTc
- Analysis of ECG parameters in real-time or offline
- Automated detection and averaging of ECG cycles
- Automated tabulation and data extraction of ECG parameters
- Automated real-time or offline ECG Plots
- Graphical QT vs RR, QT vs Time & RR vs Time plots
- Waterfall plot
Heart Rate Variability (HRV) Module (Windows or Macintosh)
The MLS310 HRV Module provides a comprehensive set of tools for the analysis and display of variation in the interval between heartbeats in human and animal electrocardiogram recordings.
The HRV module provides:
- Detects and analyzes R waves & RR interval variation in ECG real-time or offline recordings
- Includes or excludes ectopic beats from analysis
- Adds R waves or remove short artifacts from analysis
- Provides data export options
- Provides automated HRV Analysis Windows
- Poincaré Plot, Tachogram & Spectrum
- Period Histogram & Delta NN Histogram
The MLS390/6 Dose Response Module provides easy analysis of dose response type data (response to stimulation by chemical, electrical or physical agonists) recorded in LabChart from various studies including:
- Muscle contraction
- Enzyme activity
- Hormone secretion
- Heart rate
- Blood pressure
- Membrane potential
This module provides:
- Real-time or offline analysis
- Automated or manual modes of analysis
- Fast analysis of raw data to dose response parameters
- Fast comment detection and conversion to dose response markers
- Easy options for calculating different response parameters
- Instant single or multiple dose response curves (Hill-curves) generation
- Instant calculation of EC50 and Hill slopes
- Export options to other software applications for further analysis
GLP and 21 CFR Part 11
For those researchers working within a laboratory requiring GLP and 21 CFR Part 11 compliance the GLP Client and GLP Server are available for use with LabChart (Windows only) and PowerLab data acquisition systems. For more information, visit the Good Laboratory Practice application page or contact your nearest ADInstruments representative.
ADInstruments provides a number of versatile hardware solutions for Working heart experiments. There are both standard and ultimate systems for working heart experiments in a number of species from mice to rabbits. (The systems can be configured for larger animals). Working Heart Systems These systems include: Ultimate Working Heart Systems These systems include:
| Transgenic rat hearts expressing a human cardiac troponin T deletion reveal diastolic dysfunction and ventricular arrhythmias. |
| Norbert Frey, Wolfgang M. Franz, Katharina Gloeckner, Michael Degenhardt, Matthias Muller, Oliver Muller, Hartmut Merz, Hugo A. Katus, Cardiovascular Research, 254-264, 2000 |
| Rat myocardial function was evaluated using a modified isolated working heart preparation. After thoracotomy the aorta was cannulated and retrograde aortic perfusion was initiated in situ to prevent ischemia. Hearts were than rapidly excised, mounted on a perfusion apparatus (Hugo Sachs Elektronik (HSE), Germany) and perfused in a retrograde Langendorff mode with Krebs–Henseleit buffer. The buffer was equilibrated at 37 °C with 95% O2 – 5% CO2 . For ECG, monitoring suction electrodes were placed on the left ventricular apex and the right atrium, respectively. Left atrial pressure and aortic pressure were measured with an Isotec pressure transducer (HSE), intraventricular pressure with a Millar-tip catheter (HSE) inserted via the aortic valve. After 15 min of Langendorff perfusion, the hearts were switched to the working heart mode with a defined preload of 10 mmHg and afterload of 80 mmHg. Hearts were electrically paced near the sinoatrial node at 300 beats / min. Data on contractile performance were collected on-line at a sampling rate of 100 Hz with a MacLab. Parameters measured were heart rate, aortic pressure, left ventricular systolic (LVSP) and diastolic pressure and the maximal and minimal first derivatives of LVSP as a function of time (+dP/dt and -dP/dt). |
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| Protection of hearts from reperfusion injury by propofol is associated with inhibition of the mitochondrial permeability transition. |
| Sabzali A. Javadov, Kelvin H.H. Lim, Paul M. Kerr, M.-Saadah Suleiman, Gianni D. Angelini, Andrew P. Halestrap, Cardiovascular Research, 360-369, 2000 |
| Isolated rat hears were prepared for working heart perfusion. During the experiment, heart function was assessed while in the working heart mode and data were collected at 5-min intervals for analysis. An inline flow meter allowed constant visualisation of aortic flow-rate (AF). Coronary flow-rate (CF) was obtained by timed collections of coronary effluent. Pressure transducers attached to the atrial feeding and aortic outflow lines were connected to ADInstruments Bridge Ampa and a MacLab/4s which allowed for measurements of peak 'aortic’ pressure (AP), left ‘atrial’ pressure (LAP) and pressure tracing derived heart rate (HR). Cardiac output (CO) was derived by adding aortic and coronary flow-rates. Rate-pressure product (RPP), expressed as mmHg.beats/ min was calculated (AP x HR). The external cardiac work (ECW), expressed as J/s, represents the product of cardiac output and peak aortic pressure (CO x AP). |
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| Proteolytic N-terminal truncation or cardiac troponin 1 enhances ventricular diastolic function |
| J C Barbato, Q-Q Huang, M M Hossain, M Bond and J-P Jin, Journal of Biological Chemistry, 6602-6609, 2005 |
| Isolated Working Mouse Hearts of wild type and transgenic mice were measured at 5–6 months of age using the Langendorff-Neely isolated working heart preparation, at a constant preload of 10 mm Hg and an afterload of 55 mm Hg. Mice were anesthetized and the thoracic cavity was opened by a transverse incision to access the heart. Retrograde perfusion through the aorta was initiated within 60 s after removal of the heart. After establishing left atrial perfusion, the heart was switched to working mode. The hearts were perfused with Krebs-Henseleit bicarbonate buffer aerated with 95% O2, 5%CO2 at 37 °C (pH 7.4). Function of the isolated working hearts were measured on intrinsic beats at 37 °C with no artificial pacing applied.
Aortic flow and coronary effluent were collected once every 2 min over a 30-min period. Heart rate and the maximum rate of pressure development (±dP/dt) were measured using an MLT844 pressure transducer (Capto, Horten, Norway) attached to the aortic cannula. The analog signal was amplified with an ML 110 Bridge Amplifier (ADInstruments, Colorado Springs, CO), sampled at 1000 Hz by a Powerlab/16 SP digital data archiving system (AD Instruments) and stored on computer disk for subsequent analysis……….Stroke volume (ìl/g heart tissue) was calculated as the sum of aortic flow and coronary effluent, normalized to heart rate. Stroke work (ml/mm Hg/g of heart tissue) was calculated as stroke volume X average aortic pressure (diastolic pressure X one-third of pulse pressure) (mmHg). During the collection of aortic flow, time to peak pressure and the relaxation times at 10, 50, and 80% total relaxation (RT10, RT50, and RT80, respectively) were measured from the pressure traces. Systolic and diastolic pressure time integrals (STI, correlating with myocardial energy expenditure, and DTI, correlating with diastolic function and coronary perfusion (35–42), respectively) were calculated by integrating the systolic and diastolic portions of the pressure waves. |
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| Influence of substrate supply on cardiac efficiency, as measured by pressure-volume analysis in ex vivo mouse hearts |
| O-J How, E Aasum, S Kunnathu, K L Severson, E S P Myhre and T S Larsen, American Journal of Physiology: Heart and Circulatory Physiology, H2979-H2985, 2005 |
| Adult female mice were used in this study. An intraperitoneal injection of heparin (100 U) was administered 10 min before death. The animals were anesthetized with an intraperitoneal injection (10 mg) of pentobarbital sodium, after which the heart was quickly excised and the aorta cannulated with an 18-gauge plastic cannula for an initial Langendorff perfusion to wash out blood from the coronary vasculature. Oxygenated Krebs-Henseleit bicarbonate buffer (KHB, 37.5°C, pH 7.4) containing 11 mM glucose was used for this procedure. During this time, the left atrium was cannulated with a 16-gauge steel cannula with connection to the preload reservoir, and a 1.4-Fr micromanometer-conductance catheter (Millar Instruments, Houston, TX) was inserted in the left ventricle via the apex of the heart. Finally, a fiber-optic oxygen probe (FOXY-AL300; Ocean Optics, Duiven, Netherlands) was placed in the pulmonary trunk for online recording of the partial oxygen pressure of the coronary effluate. The heart was subsequently switched to the working (left ventricle ejecting) mode by opening the connection between the left atrium and the preload reservoir. In the working mode, hearts were perfused with KHB buffer (gassed with 95% oxygen using a surface oxygenator) containing 11 mM glucose and FA bound to 3% BSA (fraction V; Sigma) as energy substrates…..During stabilization, the initial filling pressure (preload) was set to 8 mmHg, whereas the afterload column was set to a height corresponding to 55 mmHg……..The ventricular function at baseline loading conditions was determined before and immediately after the buffer replacement. Left ventricular (LV) end-diastolic and end-systolic volumes and stroke volume (i.e., the difference between the end-diastolic and end-systolic volume) were calculated from the P-V loop, which was recorded by a PowerLab, Chart 5 data acquisition system (AD Instruments) and analyzed by the software accompanying the Millar P-V catheter (PVAN 2.9). Likewise, LV end-diastolic and end-systolic pressures, the first derivative of the pressure with respect to time (dP/dt), and tau (relaxation index) were determined from the P-V record. |
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The material on this page is provided in good faith and believed accurate at the time of writing. No responsibility will be taken, or liability accepted, for damages arising from the use of information herein. Readers are urged to check with respective manufacturers the accuracy of all product related information.
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