Non-Invasive Assessment of the Intraventricular Pressure Using Novel Color M-Mode Echocardiography in Animal Studies: Current Status and Future Perspectives in Veterinary Medicine

SIMPLE SUMMARY: Traditional echocardiographic imaging mainly identifies cardiac diseases when symptoms are clear. This makes the innovation of new methods for the prediction and early diagnosis of cardiac diseases inevitable, especially when diastolic function evaluation is needed. Generally, non-invasive assessment of heart function is currently attracting great attention away from sophisticated techniques. With the development of color M-mode echocardiography (CMME), the derived intraventricular pressure differences (IVPDs) and intraventricular pressure gradients (IVPGs) created a breakthrough in the non-invasive assessment of diastolic function in animal models as well as in some companion animals and human studies. They are beneficial for continuous data acquisition without invasive interference, and their results showed good relatedness with the measurements acquired from the catheterization technique. ABSTRACT: The assessment of diastolic function has received great interest in order to comprehend its crucial role in the pathophysiology of heart failure and for the early identification of cardiac events. Silent changes in the intraventricular flow (IVF) dynamics occur before the deterioration of the cardiac wall, although they cannot be detected using conventional echocardiography. Collective information on left ventricular (LV) pressures throughout the cardiac cycle has great value when dealing with patients with altered hemodynamics. Accurate pressure measurement inside the ventricle can be obtained by invasive methods to determine the LV diastolic pressures, which reflect the myocardial relaxation and compliance. However, catheterization is only feasible in the laboratory setting and is not suitable for clinical use due to its disadvantages. In contrast, echocardiography is simple, safe, and accessible. Color M-mode echocardiography (CMME) is an advanced cardiac evaluation technique that can measure the intraventricular pressure differences (IVPDs) and intraventricular pressure gradients (IVPGs) based on the Doppler shift of the IVF. Recently, the assessment of IVPD and IVPG has gained growing interest in the cardiovascular literature in both animal and human studies as a non-invasive method for the early diagnosis of cardiac dysfunctions, especially diastolic ones. The usability of IVPD and IVPG has been reported in various surgically induced heart failure or pharmacologically altered cardiac functions in rats, dogs, cats, and goats. This report aims to give an overview of the current studies of CMME-derived IVPD and IVPG in animal studies and its feasibility for clinical application in veterinary practice and to provide the prospects of the technique’s ability to improve our understanding.