However, these parameters are all considered to be load-dependent (influenced by the preload or afterload of the heart), whereas true contractility is a load-independent phenomenon. Related: Importance of PV Catheter Calibration in Admittance and Conductance Systems » You can also calculate parameters such as stroke work, Tau, dP/dt Max and Min, contraction time, and relaxation time - all of which are associated with the term 'contractility.' Similar to echo and MRI, PV catheters allow you to measure end-diastolic volumes and end-systolic volumes, and from these, calculate the stroke volume, ejection fraction, and cardiac output. The video below shows a handful of commonly reported cardiac parameters that can be measured with a PV catheter. By inserting a PV catheter into the left or right ventricle of an anesthetized animal, you can measure all load-dependent data for every cardiac cycle from the moment you complete your instrument until the end of the experiment. Pressure-volume catheters provide a unique method for acquiring hemodynamic and contractile data directly from the heart. These limitations are what set PV catheters apart from echo and MRI, as you can simultaneously collect load-dependent AND load-independent data throughout the entire experiment. Although, this comes with a notable caveat, being that significant acclimation needs to occur before recording any data, as the stress of the procedure can introduce experimental bias.Įach system has its own unique set of limitations highlighted in the video above, but two that they hold in common are they only capture data over short periods, and that cardiac functional measures are largely load-dependent. Another appealing aspect to echo is that it can be performed on conscious animals. However, MRI will give you better blood tissue contrast and greater spatial resolution. #Cardiac index to ejection fraction converter serial#As with any tool, they have their advantages and disadvantages, but what you find in common between the two is the ability to perform serial measurements and assess cardiac chamber structure.Įcho is generally more available and portable than MRI. Echocardiography and cardiac MRI are the two primary non-PV modalities used for assessing cardiac function in mice.
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