动物造模,心律失常模型 z-bio 2022-01-12 437

　　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. Choose dogs, cats and other animals for atrial flutter and atrial fibrillation arrhythmia. After anesthesia, the chest cavity was opened, the heart was exposed, and the experiment was performed under artificial respiration. High-frequency electricity can be used to directly stimulate the atrial wall, so when the atrial muscle is repolarized, each stimulus is an R wave or S wave interval. The aconitine solution is applied to the outside of the atrium, squeezing the animal during this time. During electrical stimulation, the superior and inferior vena cava; inject acetylcholine or thyroxine preparations into the sinoatrial node artery. Or, with the chest closed, use the animal to block the respiratory tract or inhale hypoxic gas. The separated atrial tissue block can also be used for experiments, and the separated mammalian atrial tissue block (including the sinoatrial node) is immersed in a low potassium solution.

　　2. Ventricular tachycardia, ventricular fibrillation arrhythmia are mainly performed in the entire 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 of action of antiarrhythmic drugs and self-control.

　　3. Atrioventricular block and conduction arrhythmia at the atrioventricular junction are mainly dogs and cats. When the heart is exposed under anesthesia, it is injected into the left ventricular myocardium 1.5-2 cm from the apex of the dog's heart. Normal saline (80-90°C) or 95% alcohol, 10-15 ml of 25% sulfuric acid (injecting 4-7 ml of sulfuric acid into cats and rabbits) can cause local necrotizing arrhythmia in the large myocardium. It is also possible to puncture the atrio-ventricle below the interatrial 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 stroke time 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. In male rabbits with sinus nodular arrhythmia, a thin steel wire forms a half ring with a diameter of about 0.8 cm and is wrapped with a little cotton cloth. After infiltration of 40% formaldehyde, place the ring at the junction of the root of the superior vena cava and the right atrium for 1 minute. The animal's electrocardiogram changes rapidly, and its heart rate drops by about 50%. It drops to the lowest level in about 6-8 minutes; P wave is almost there, disappears within 1-2 minutes and forms a critical heart rhythm; ST segment deviation (first rise, fall or rise), then fall) 3-10 Minutes; a decrease in arterial pressure accompanied by changes in ECG. The number of minutes has dropped to a minimum. This method has a high success rate of sinus syndrome, a long duration (up to 5 hours), high reproducibility, stable model, and similar etiology and ECG performance.