Measurement of right intraventricular pressure in anesthetized rabbits and rats

Summary

This experiment is from the official website of the Fourth Military Medical University

Operation method

Measurement of right intraventricular pressure in anesthetized rabbits and rats

Principle

Changes in the right ventricular pressure (RVP) of the heart mainly reflect the systolic and diastolic function of the right ventricle. Changes in right ventricular systolic and diastolic function are influenced by two factors: changes in the contractile and diastolic properties of the right ventricular myocardium itself, and changes in the pressures within the pulmonary circulation, such as in pulmonary hypertension (hypertension). Normally, a special plastic catheter is inserted from the right external jugular vein, sent to the superior vena cava, into the right atrium, and then into the right ventricle for the measurement of right ventricular internal pressure, a measurement that is somewhat difficult.

Materials and Instruments

Rabbit Rat
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

Move

1. Laboratory animals and equipmentRabbits, weighing about 2 kg; rats, weighing about 200-250 g. 20% urethane injection or 1.5% pentobarbital sodium injection, 1% procaine injection, 0.3% heparin saline injection, a set of commonly used experimental instruments, a laboratory table for rabbits or rats, pressure transducer and its multi-channel physiological signal acquisition and recording equipment. Flexible plastic catheters for rabbits or rats (outer diameter of 2 mm, inner diameter of 1.5 mm for rabbits; outer diameter of 1 mm, inner diameter of 0.8 mm for rats), specially processed so that the catheter has a certain degree of curvature at the end of the catheter (Figure 1).


Figure 12. Experimental methodological stepsOne rat was taken, weighed about 200~250 g. It was anesthetized with 20% urethane injection 0.5 ml/100 g or 1.5% pentobarbital sodium injection 0.2 ml/100 g by intraperitoneal injection, and after the animal was anesthetized, it was fixed on the experimental table and the neck was clipped. The skin in the middle of the neck was cut with surgical scissors, and the right subcutaneous tissue was separated, i.e., the external jugular vein could be seen. The venous vessels of about 1 cm in length were gently separated with ophthalmic forceps, and two surgical threads were threaded at the distal and proximal ends respectively for backup. Before cannulation, the plastic catheter and pressure transducer were filled with 0.3% heparin saline injection, air bubbles were drained away, and the pressure range displayed on the recorder was adjusted to the range of 0-50 mmHg. Then the distal end of the external jugular vein was ligated first, and the proximal surgical wire was gently lifted up, and a cut was made with ophthalmic scissors at an angle of 45° in the wall of the vein at the distal end of the ligature, and the special plastic catheter was inserted into the external jugular vein, and the blood vessel and catheter were ligated with the proximal surgical wire but not too tightly, so that the catheter could be continued to be inserted. Observe the waveform of venous pressure on the recorder. Continuing to feed the catheter slowly, the right atrium can be reached, and the waveform of the pressure within the right atrium is seen, with an amplitude of about 0 to 5 mmHg or so. As the catheter passes from the right atrium into the right ventricle, it is sometimes easy to enter the right ventricle and see a waveform of intra-ventricular pressure that is completely different from the waveform of intra-atrial pressure, with an amplitude ranging from about 0 to 25 mmHg, because of the difference in the appropriateness of the curvature of the tip portion of the catheter. Sometimes it is difficult to enter the right ventricle, and several more attempts are required.

Caveat

The proper curvature of the tip portion of the catheter is a very important part of the method of cannulating from the right external jugular vein to reach the right ventricle for right ventricular internal pressure measurement. With a small bend, the catheter tends to slip inside the right atrium into the inferior vena cava, whereas with too large a bend, the catheter may loop inside the right atrium and not enter the right ventricle.

Common Problems

Since the right ventricle is closely related to the pulmonary circulation, in most cases, changes in right ventricular pressure (RVP) are mainly used to reflect and evaluate changes in the function of the pulmonary circulation. For example, in patients with pulmonary heart disease, it is due to long-term, chronic lung disease, causing increased pulmonary artery pressure, involving the right ventricular pressure also increases, when the involvement is so severe that the right heart loses the ability to compensate, but also can occur in heart failure. Therefore, the change of right ventricular pressure is an important indicator to reflect and evaluate the change of pulmonary circulation function.

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