This protocol describes a method for measuring left ventricular pressure and volume using the pressure-volume conductance technique. This method enables continuous real-time monitoring of the effects of drugs on the heart.
Decreased cardiac function can have a negative impact on other organs. The left ventricular pressure-volume relationship is considered to be a valid method for evaluating cardiac function. Real-time monitoring of cardiac function is important for drug evaluation. Under closed-chest conditions, the miniature transducer, which is an important component of the pressure-volume catheter, enters the left ventricle of the rat through the right carotid artery. The device visualizes the changes in cardiac function during the experiment in the form of a pressure-volume loop. The actual volume of the ventricle is calculated by altering the conductivity of the blood by injecting 50 µL of a 20% sodium chloride solution into the rat’s left jugular vein. The actual volume of the rat’s ventricular cavity is calculated by measuring the conductivity of the blood in a known volume using a pressure-volume conductance catheter. This protocol allows for continuous observation of the effects of drugs on the heart and will promote the rationale for the use of specialty ethnic drugs in cardiovascular disease.
Cardiovascular disease has the highest mortality rate in the world1. Its causes include coronary artery stenosis (myocardial ischemia), coronary artery blockage (myocardial infarction), and ischemia-reperfusion injury2. As the heart is in a constant systolic and diastolic cycle, it is one of the most energy-demanding parts of the body. Therefore, when the coronary arteries have difficulty maintaining sufficient energy and oxygen, cardiac function inevitably decreases, which has a negative impact on other organs3,4. The heart is a powerhouse in the circulatory system, and cardiac function needs to be assessed rationally.
Assessment of cardiac function by ventricular pressure and volume relationships is considered to be a comprehensive method5. Real-time changes in ventricular pressure and volume during the complete cardiac cycle make up the pressure-volume loop. The ventricular pressure-volume loop allows quantitative analysis of cardiac function and reserve capacity in terms of different phases and energies of the ventricle. The normal ventricle has a small end-systolic volume with good beat work and efficiency5,6,7.
The pressure-volume conduction catheter technique is an invasive method for detecting the status of the left ventricle. It can be used to obtain a continuous real-time pressure-volume loop8. Pressure volumetric conductivity catheters are powerful tools, and sound handling procedures are essential for reproducible and reliable results, including in vivo analysis of myocardial parallel conductivity during saline calibration and in vitro measurement of blood conductivity in cuvette calibration3.
Ferulic acid (FA), a phenolic acid, is widely distributed in plant kingdoms such as Avena sativa and Ligusticum chuanxiong hort9,10. Ferulic acid has pharmacological effects of lowering blood pressure and arrhythmia. FA is a bioactive natural product with multiple functions. FA can resist oxidative damage, reduce inflammatory responses, inhibit platelet aggregation, and prevent coronary heart disease and atherosclerosis11. However, most studies on ferulic acid have focused on one aspect of the heart and rarely have the effects of ferulic acid been evaluated in the circulatory system12,13,14,15. Here we describe a closed-chest approach to isoflurane anesthesia combined with Ketamine (50 mg/kg) with a focus on the cardiac response to ferulic acid solution during jugular vein injection.
We will describe the complete procedure for using the tool under closed-chest conditions, including solution preparation, preparation of the transducer, pre-experimental rat preparation, catheter insertion into the right carotid artery and data analysis. The duration of the experiment is usually less than 4 h and it is determined by the different experimental protocols. In a single experiment, we can obtain detailed cardiac information such as left ventricular pressure, volume, and heart rate.
It is essential to adopt a rational dosing strategy for different states of cardiac function. The pressure-volume conductance catheter technique is the most intuitive way to study left ventricular function5. This method enables the effects of drugs on cardiac function to be studied from a whole perspective. We describe the various stages of the experiment in detail. This will provide some facility for the study of heart function.
The pressure volume conductivity cathete…
The authors have nothing to disclose.
This work was supported by the Sichuan Provincial Major R&D Project (2022YFS043) and the Chengdu University of Traditional Chinese Medicine Youth Foundation Advancement Talent Special Project (QJJJ2022029).
1 mL syringe | Sartorius AG, Germany | – | |
Animal temperature maintainer | Rayward Life Technology Co., Ltd | 69020 | |
Dual Bio Amp | Millar, Inc., USA | DA-100 | |
Enzyme-Active Powdered Detergent | Alconox Inc., USA | 1104 | |
Ferulic acid | Macklin Biochemical Co., Ltd,Shanghai, China | F900027 | |
Mikro-Tip Catheter Transducers, SPR-838NR | Millar, Inc., USA | SPR-838NR | |
Millar Miro-Tip Pressure Volume (MPVS) Ultra | Millar, Inc., USA | SPR-869 | |
Pet electric clippers | Jinyun County New Concept Home Supplies Co., Ltd. | - | |
Power Lab 8 / 35 | Millar, Inc., USA | PL3508 | |
Sodium Chloride, NaCl | Kelong Chemical Reagent, Chengdu, China | KX829463 | |
Veet hair removal cream | Shanghai Songqi E-commerce Co., Ltd. | 3226470 |