This experiment is from the official website of the Fourth Military Medical University
Operation method
Experiments on the determination of left intraventricular pressure and the rate of change of left intraventricular pressure in anesthetized rabbits and rats
Principle
The left ventricular pressure (LVP) and its rate of change are important indicators for reflecting and evaluating the systolic and diastolic functions of the left ventricle, which are often used in clinical cardiac catheterization, as well as in experimental teaching and scientific research in basic medicine. In general, rabbits and rats can be catheterized through the common carotid artery to reach the left ventricle of the heart to obtain the indexes reflecting the systolic and diastolic functions of the left ventricle, and the operation is simple and easy to implement. In addition, in rats, the left ventricle can be reached via the apical portion of the left ventricle, and the indexes of left ventricular systolic and diastolic function can be measured by cannulation of the left ventricle. This measurement method allows the measurement of left ventricular systolic and diastolic function while at the same time obtaining indicators of cardiac pump function. This method requires open-heart surgery to expose the heart, so a small animal artificial respirator is used to assist breathing.
Materials and Instruments
Rabbit Rat Move 1. One rabbit was taken, weighed, and anesthetized by intravenous injection of 20% urethane injection 5 ml/kg or 1.5% pentobarbital sodium injection 2 ml/kg via the ear margin, and the injection speed should not be too fast. After the animals were anesthetized, they were fixed on the experimental table, and their necks were clipped and prepared for surgery. Local infiltration anesthesia can be applied with 1% procaine injection 2 ml subcutaneously in the middle of the neck, the skin in the middle of the neck is cut with a scalpel (rats are cut with surgical scissors), and the trachea is exposed by bluntly separating the subcutaneous tissues and muscles covering the top of the trachea with vascular forceps. On the right and left sides of the trachea, the red-colored common carotid artery and the white vagus nerve can be seen in the same sheath, and the right common carotid artery is usually chosen to cannulate into the left ventricle. The sheath is gently opened with vascular clamps, and the right common carotid artery is isolated for 2 to 4 cm, and two surgical lines are threaded distally and proximally for backup. Before cannulation, the catheter and pressure transducer were filled with 0.3% heparin saline injection, air bubbles were drained away, and recording instruments were prepared. Then the distal end of the common carotid artery was ligated first, and the proximal end was clamped with an arterial clip. A cut was made in the arterial wall at the distal ligation with ophthalmic scissors at an angle of 45°, and the prepared common carotid artery catheter was inserted proximally for about 2 cm, and the arterial vasculature and the catheter were ligated with a threaded wire at the proximal end, but not too tightly, so that the catheter could be continued to be inserted. Loosen the arterial clip to feed the catheter in about 2 cm further, and record the blood pressure waveform in a segment of the common carotid artery. Pinch the vessel and cannula at the cutout with the left finger, and gently feed the catheter down toward the heart with the right hand. When the catheter passes through the common carotid artery and the aortic arch to reach the aortic valve orifice, the amplitude of the waveform of the blood pressure will be a little bigger, and the finger can feel the heart beating obviously, then continue to feed the catheter down to the left ventricle, and the waveforms of the left ventricular intraventricular pressure and rate of change of the left ventricular pressure will be recorded, see Fig. 9-40. According to the recorded waveforms, gently adjust the position of the catheter, and then the proximal end of the threading line tied, and then the distal end of the ligature line ligature, fixed catheter, you can carry out the experimental content.2、Methods of transcatheter left ventricular apical intubation in rats: one rat was taken, weighed, and anesthetized with 20% urethane injection 0.5 ml/100g or 1.5% pentobarbital sodium injection 0.2 ml/100g, intraperitoneal injection, and then, after the animal was anesthetized, it was fixed in the experimental table, and the neck and chest were clipped. The skin in the middle of the neck was cut with surgical scissors, and the subcutaneous tissue and the muscle covering the top of the trachea were bluntly separated with vascular forceps to expose the trachea, tracheal intubation was performed, and the artificial respirator was turned on for artificial respiration. To perform an open thoracotomy, the skin was cut along the middle of the sternum, the 5th, 4th, 3rd, and 2nd ribs were cut tightly against the left edge of the sternum, and the hemorrhage was stopped by cautery with a cauterizer to enter the thoracic cavity, and the tidal volume of the artificial respirator was adjusted until the lungs were moderately inflated bilaterally. The incision was pulled open with a small pull hook, the pericardium was opened, a purse-string suture loop was made at the left ventricular apex with an ophthalmic suture needle, a short silk thread was ligated 1 cm from the mouth of the prepared ventricular catheter, and then the catheter, which was well connected to the pressure transducer, was inserted directly into the purse-string suture loop at the apex, ligated with a purse-string suture, and secured with a ligated thread on the mouth of the catheter so that the catheter would not slip out of the apical port, and it was possible to The waveforms of LV internal pressure and the rate of change of LV internal pressure were recorded (Fig. 1). Caveat When intubating via the common carotid artery, the mouth of the catheter must not be too sharp, especially when rats are used for experiments, otherwise it is easy to break the vessel wall and hemorrhage occurs. Before intubation, the outer wall of the catheter should be coated with liquid paraffin so that there is less resistance and the catheter can be easily delivered into the left ventricle. In addition, in the process of intubation, if the original amplitude of the blood pressure waveform, suddenly become smaller or become a straight line, it may be the mouth of the catheter against the wall of the arterial vessels, or against the aortic valve, then you should be gently back a little catheter, or rotate the direction of the catheter, so that the original waveform of the blood pressure appeared and then continue to feed the left ventricle into the left ventricle. Remember that when there is no blood pressure waveform, do not send down the catheter, which is easy to rupture the vessel wall. When the catheter is inserted through the apical portion of the left ventricle, the catheter opening must be pointed so that it is easy to penetrate the wall of the left ventricle and enter the cavity of the left ventricle. Common Problems Intra-ventricular pressure and its rate of change in the left ventricle of the heart are important indicators to reflect and evaluate the systolic and diastolic functions of the left ventricle. The following indices can be obtained by cannulating through the common carotid artery or cannulating through the apical portion of the left ventricle to reach the left ventricle: left ventricular systolic pressure (LVSP), left ventricular diastolic pressure (LVDP), left ventricular 舒张末压（left ventricular end-diastolic pressure, LVEDP），左心室内压最大上升速率（+dp/dtmax）、左心室内压最大下降速率（-dp/dtmax）、心率（heart rate, HR）。 Indicators of arterial blood pressure (BP) are also available, including arterial systolic blood pressure (SBP), arterial diastolic blood pressure (DBP), and mean arterial pressure (MBP). Among these indexes, left ventricular systolic blood pressure (LVSP) and maximum rate of increase in left ventricular internal pressure (LVIP) mainly reflect the systolic function of the left ventricle; left ventricular diastolic blood pressure (LVDP), left ventricular end-diastolic blood pressure (LVEDP), and maximum rate of decrease in left ventricular internal pressure (LVIP) mainly reflect the diastolic function of the left ventricle. < For more product details, please visit Aladdin Scientific website.
Ethyl carbamate Sodium pentobarbital Procaine injection Heparin
Animal laboratory bench Plastic catheter Water pressure meter Pressure transducer Multi-channel physiological signal acquisition and recording equipment
Figure 1