ECG & Pulse Doppler Systems For Cardiovascular Research on Mice
Electronics Contract R&D For Medical, Scientific, & Industrial Instrumentation
 
 
     
   
   
   
   
   
   
   
   
   

Doppler Mainframe Modules

10 OR 20 MHZ PULSED DOPPLER MODULE                          
This module is suitable for most flow velocity measurements in smaller (20 MHz) and larger (10 MHz) vessels of acute and chronically instrumented animals. The output is directional with either advancing or receding flow displayed as positive. Outputs are mean velocity, phasic velocity with selectable damping, and a voltage proportional to the range gate delay. Doppler shifts up to 31.25 kHz can be measured with the standard 62.5 kHz pulse repetition frequency (PRF). This corresponds to a maximum velocity of 166 cm/s using a 20 MHz probe or 330 cm/s using a 10 MHz probe with a beam angle of 45 degrees. These modules can also be used with tubing mounted probes to measure blood flow noninvasively in mice and other animals.        
                       
                     
          HIGH VELOCITY 10 OR 20 MHZ PULSED DOPPLER MODULE        
This module was designed to overcome the high velocity limitation of the standard module. By "unwrapping" the aliased high frequencies, it can record Doppler shifts up to 62.5 kHz (~300 cm/sec at 20 MHz or ~600 cm/sec at 10 MHz) using the standard 62.5 kHz PRF. Because of these extra features it is trickier to use (more critical controls to set) than the standard module. It has been found it most useful on hepatic, renal, and mesenteric arteries.
                   
                 
 
WIDEBAND TRANSIT-TIME DIMENSION GAUGE MODULE        
This is the standard transit-time dimension gauge (sonomicrometer) used with paired ultrasonic crystals for measuring myocardial segment length, wall thickness, and diameter and for measuring blood vessel diameter. Dimensions from 2 to 50 mm can be measured from up to 4 sets of crystals (requiring 4 modules) simultaneously without interference. This module can be used with crystals ranging in frequency from 5-20 MHz.    
 
         
      10 OR 20 MHZ SINGLE CRYSTAL DISPLACEMENT MODULE    
This module is used to measure ventricular thickening from a single epicardial transducer, thus eliminating the need for any intramyocardial crystals. Rather than tracking one layer, it measures thickening at a fixed depth from the epicardial surface as selected by the range gate delay. Thickening fraction is estimated by dividing the measured thickening (in mm) by the range gate depth (also in mm) which can be set to any depth from the subepicardium to the subendocardium. Although it doesn't measure absolute thickness, it is much easier to use than the two crystal method, and has been very useful in evaluating regional ventricular function in studies of ischemia and reperfusion. Resolution is 0.02 (0.01) mm with a maximum measurable thickening of 5 (2.5) mm at a maximum depth of 4 (1.2) cm at 10 (20) MHz.
 
   
DUAL PRESSURE AMPLIFIER MODULE    
This non-ultrasound module contains two standard bridge amplifiers suitable for use with pressure transducers such as those made by Gould Statham, Konigsberg, or Millar. Each amplifier is independent with input connector, balance and gain controls, and a phasic/zero/mean output selector switch. The lower amplifier has an additional mean output which is not affected by the selector switch.  
 
           
  PRESSURE DIFFERENTIATOR MODULE        
This module contains a single pressure amplifier as above and also a derivative amplifier and calibrator for dP/dt measurement. Simultaneous outputs are provided for phasic pressure, mean pressure, and dP/dt. A built-in triangle wave generator is used to calibrate the dP/dt output in mmHg/s.
       
     
ECG/RATE MODULE        
This module contains a differential ECG amplifier with standard lead switching, an R-wave trigger, and a rate counter. The standard lead set has four limb leads, 2 V leads, and a ground. A cable is also available for direct connection to the “MousePad” ECG board, A simpler module with a 3-lead clip-cable and manual lead switching is also available. Outputs from each module include: ECG, heart rate, and a pulse coincident with the triggered R-wave.    
 
           
  TEMPERATURE MODULE            
This is the Temperature Controller Module that allows for automatic thermal control of the heating pad incorporated on the ECG board, while the temperature of the mouse is monitored with a rectal probe plugged into the port labeled "MOUSE" in blue (see picture to the left). The heating pad uses feedback from either the probe or the heating pad to monitor the temperature and ensure the mouse’s required body temperature is maintained.  
 
   
5 MHZ MODULE    
This module is suitable for flow velocity measurements in animals larger than mice (rats, rabbits, guinea pigs, etc.). The output is directional with either advancing or receding flow displayed as positive. Outputs are mean velocity, phasic velocity with selectable PRF, and a voltage proportional to the range gate delay. Doppler shifts depend on PRF selection (low, medium, high). The low setting is ¼ of the mainframe PRF, the medium setting is ½ of the mainframe PRF, and the high setting is equal to the mainframe PRF. The mainframe PRF can be set to either 125kHz or 62.5kHz.