疾病动物造模,心律失常 z-bio 2021-12-15 416

　　(1) Copy method New Zealand rabbits weighing about 2.5kg are anesthetized by intravenous injection of 3% sodium pentobarbital at a dose of 30mg/kg body weight, and fixed in lateral position; needle electrodes are inserted into the rabbit limbs under the skin to connect to the electrocardiograph and electrocardiogram Oscilloscope, make the Ⅱ lead electrocardiogram of limb leads; cut the neck skin in the middle, separate the trachea and insert the tracheal cannula, connect to the ventilator for artificial respiration, breathing rate 50 times/min, tidal volume 35ml; then 4th from the left , The fifth intercostal thoracotomy, cut the open heart bag about 0.5cm along the side of the phrenic nerve to make the pericardial bed, and use 2 small stainless steel frog heart clamps to make the electrodes respectively in the apex (positive electrode) and near the left ventricular atrioventricular groove On the epicardium (negative electrode), the distance between the two electrodes is about 1cm, connected to an electronic stimulator, stimulated with a series of pulses, frequency 50Hz, wave width 0.3ms, string length 10s, constant voltage output, stimulated every 3min . The stimulus intensity was increased successively, with an increase of 2V each time, until the ventricular fibrillation (VF) waveform appeared on the ECG. After ventricular fibrillation, the interval was 5min-repeated again and the measurement was repeated once, and the average value of the voltage caused by the two ventricular fibrillation was used as the ventricular fibrillation threshold (VFT) before administration. If the ventricular fibrillation cannot recover by itself 5s, you can directly massage the heart with your hands or directly defibrillate the heart with a defibrillator. Then the test drug was injected intravenously at 1ml/kg body weight. The negative control group was injected with the same volume of normal saline, and the injection was completed in 1 minute, and then stimulated after 3 minutes. The ventricular fibrillation threshold after administration was measured in the same way, and the ventricular fibrillation threshold was calculated. Added value.

　　This model can also fix the rabbit in the supine position after anesthesia, cut the middle of the sternum, cut the heart bag, be careful not to break the pleura, and perform artificial respiration without a ventilator for experiments. Electrical stimulation is currently also commonly used constant current stimulation as a threshold indicator. It is best to connect the stimulator to the heart through a stimulation isolator.

　　model making can also be done with dogs. After the dog was anesthetized with 3% sodium pentobarbital at a dose of 30 mg/kg body weight, the tracheal intubation was connected to the ventilator, and positive pressure artificial respiration was performed. The left side was fixed and the third and fourth intercostal chest were opened. Expose the pericardium, cut the open heart bag along the side of the vagus nerve and suture it to the chest wall. The stainless steel stimulating electrode was placed on the anterior wall of the left ventricle, the irrelevant electrode was placed at the atrioventricular sulcus, or under the skin of the thigh. Perform series stimulation at regular intervals, with a frequency of 50 Hz, a wave width of 0.3 to 3 ms, and a string length of 0.2 to 2 s. Adjust the stimulation intensity with constant pressure or constant current according to the different stimulators, and gradually increase the stimulation intensity until ventricular fibrillation occurs. The stimulator output intensity (voltage or current) is used as the ventricular fibrillation threshold (VFT). There is also a program-controlled stimulation method to determine VFT. First, a continuous constant square wave with a time duration of 400ms and a wave width of 3ms is used as the basis to stimulate the pacemaker. After every 18 basic stimuli, a series of stimulations of 0.2～1.8s and a frequency of 50Hz are given 100ms. Increase the stimulation intensity gradually until ventricular fibrillation occurs. If ventricular fibrillation lasts for a long time, a defibrillator can be used for defibrillation. The test can also be carried out with cats in the same way as rabbits and dogs. Dogs can also carry out dual studies of anti-atrial reentrant activation and anti-ventricular fibrillation at the same time. The model of reentrant excitement: between the upper and lower veins and the tissue parallel to the atrioventricular sulcus, it is formed by surgical Y-shaped extrusion, and then stimulated by string Determine ventricular fibrillation threshold.

　　(2) Characteristics of the model Rabbits and cats can self-regulate after ventricular fibrillation, while dogs’ ventricular fibrillation is more difficult to recover on their own and require electrical defibrillation. The experiment can be more precise and quantitative. The parameters of electrical stimulation are fixed. The threshold of ventricular fibrillation caused by repeated stimulation of the same animal is very stable. After antiarrhythmic drugs are given, the threshold of ventricular fibrillation in the same animal is observed and compared with itself, the accuracy is high. . Moreover, most of the various types of antiarrhythmic drugs are effective in this model, and it is not easy to produce drug resistance. It is the most commonly used model for the study of antiarrhythmia.

　　(3) Comparative medicine Electrical stimulation of the heart to induce arrhythmia is a very traditional model. As long as the appropriate stimulation intensity is controlled, there is no obvious damage to the myocardium, and it is closer to the clinical natural ectopic impulse than other methods.