疾病动物模型,心律失常 z-bio 2021-03-08 266

　　Arrhythmia can be reproduced in the whole animal, or perfused in vitro by in vitro perfusion of an isolated heart or a specific part of the heart, depending on various experimental purposes. The most commonly used copy method is:

　　1, Atrial flutter and fibrillating arrhythmia

　　Select dogs, cats and other animals, open the chest cavity after anesthesia, expose the heart, and conduct experiments under mechanical ventilation. High-frequency electricity can be used to directly stimulate the atrial wall, so if the atrial muscle is repolarized during each stimulation, the R wave or S wave will separate. Aconitine solution is applied to the outside of the atrium. It compresses the superior and inferior vena cava and provides electrical stimulation at the same time. A preparation of acetylcholine or thyroxine is injected into the atrial nodular artery. Or, with the chest closed, use the animal to block the respiratory tract or inhale hypoxic gas. The separated pieces of atrial tissue can also be used in experiments. The separated pieces of mammalian atrial tissue (including the sinoatrial node) are immersed in a low potassium solution.

　　2. Ventricular tachycardia and ventricular fibrillation arrhythmia are mainly used for experiments on the whole heart (open or closed) of dogs, cats, rabbits, rats, etc. Commonly used styling drugs are aconitine, digitalis and epinephrine. Usually, aconitine is injected slowly intravenously. Dose: 100-150μg/kg for rabbits, 30-50 mg/kg for rats, 5 mg/kg for mice. You can also use toxic digitalis styling. High concentrations of epinephrine (40μg/kg for guinea pigs and 100μg/kg for cats and dogs) can also be used for rapid intravenous injection, which may cause multiple heart contractions and short-term ventricular tachycardia in animals. Such a model can be used to screen antiarrhythmic drugs. The advantage is that the arrhythmia disappears spontaneously within a few minutes, and the arrhythmia of the same animal can be tested repeatedly. This is useful for observing the duration and self-control of antiarrhythmic drugs.

　　3. Atrioventricular block and conduction arrhythmia at the atrioventricular junction are mainly cats and dogs. The chest cavity is opened to expose the heart. The left ventricular myocardium is 1.5-2 cm away from the apex of the dog's heart. Inject 10-15 ml of thermophysiology. Normal saline (80-90°C) or 95% alcohol and 25% sulfuric acid (injecting 4-7 ml into cats and rabbits) can cause local necrosis of the large myocardium, which can cause arrhythmia. It is also possible to puncture the atrio-ventricle below the atrial septum with a needle at the dog’s atrioventricular junction (ie, approximately 0.5 cm above the intersection of the left lower atrium, atrium, and inferior vena cava). Slowly inject 2-5 ml of 95% or absolute alcohol into the nodule area, causing nuclear tissue necrosis. Guinea pigs can also be used to inject 5μg adenosine from the left atrial appendage to the left atrium. About 1 second after the injection, a typical conduction block of degree II or higher appeared. In more severe cases, the atrioventricular arrest is complete. There is a parallel relationship between downtime and dose, and heart rate and heart rhythm can be restored in a few seconds or 10 seconds. Although the model is reproducible, it has a short duration of conduction block and is not easy to use for drug observation. Injecting large amounts of adenosine is not easy to restore the conduction block. Except for guinea pigs, adenosine does not usually cause conduction block in other animals.

　　4. Use sinus arrhythmia

　　For male rabbits, the thin steel wire is turned into a half ring with a diameter of about 0.8 cm and wrapped with a small cotton pad. After infiltration of 40% formaldehyde, the ring is placed at the junction of the root of the superior vena cava and the right atrium for 1 minute. These animals immediately showed changes in the electrocardiogram, and their heart rate dropped by about 50%. It drops to the lowest level in about 6-8 minutes. The P wave almost disappears within a minute or two, forming a critical heart rhythm. Within 3-10 minutes, the range of motion of the ST segment occurs (first rise, fall or rise, and then fall); when the ECG changes, it is accompanied by a drop in arterial pressure. The number of minutes has dropped to a minimum. This method has a high success rate of sinus syndrome, duration (up to 5 hours), high reproducibility, stable model, and clinically similar etiology and ECG performance.