Aortic acceleration as a noninvasive index of left ventricular contractility in the mouse

Abstract

The maximum value of the first derivative of the invasively measured left ventricular (LV) pressure (+ dP/dtmax or P′) is often used to quantify LV contractility, which in mice is limited to a single terminal study. Thus, determination of P′ in mouse longitudinal/serial studies requires a group of mice at each desired time point resulting in “pseudo” serial measurements. Alternatively, a noninvasive surrogate for P′ will allow for repeated measurements on the same group of mice, thereby minimizing physiological variability and requiring fewer animals. In this study we evaluated aortic acceleration and other parameters of aortic flow velocity as noninvasive indices of LV contractility in mice. We simultaneously measured LV pressure invasively with an intravascular pressure catheter and aortic flow velocity noninvasively with a pulsed Doppler probe in mice, at baseline and after the administration of the positive inotrope, dobutamine. Regression analysis of P′ versus peak aortic velocity (vp), peak velocity squared/rise time (vp2/T), peak (+ dvp/dt or v′p) and mean (+ dvm/dt or v′m) aortic acceleration showed a high degree of association (P′ versus: vp, r2 = 0.77; vp2/T, r2 = 0.86; v′p, r2 = 0.80; and v′m, r2 = 0.89). The results suggest that mean or peak aortic acceleration or the other parameters may be used as a noninvasive index of LV contractility.

Haemodynamic Effects of Pimobendan during General Anaesthesia in Healthy Senior Dogs: A Prospective, Randomised, Triple-Blinded, Placebo-Controlled Clinical Study

“…This catheter can measure the maximal rate of rise of left ventricular pressure (LV dP/dtmax). This parameter is widely used to assess contractility in several species [ 39 , 40 , 41 ]. The effects of pimobendan on inotropism appear less pronounced in anaesthetised dogs than in awake dogs [ 38 ].…”

“…In the present study, PV and MA were used to assess changes in inotropism: PV is the maximum velocity of blood in the aorta, and MA is the slope of the aortic velocity curve. These two parameters have previously been used to assess cardiac inotropism and have proven to be good indicators of a range of contractility situations in humans, mice, and dogs [ 39 , 40 , 41 ]. PV and MA reasonably correlate with LV dP/dtmax [ 42 ].…”

“…The results could have been different if cardiac contractility had been measured by invasive methods at the intraventricular level. All haemodynamic parameters studied in this study (i.e., PV, MA, and VTI) are affected by cardiac contractility and preload and afterload [ 40 , 41 , 42 ]. Preload was not assessed in this study, but there were no signs of hypovolemia in any dogs on pre-anaesthetic examination and anamnesis.…”

Echocardiography protocol: A tool for infrequently used parameters in mice

“…Mitral regurgitation (MR) has not been well-described in mice because of their resistance to developing mitral valve prolapse ( 11 ). However, Li et al recently reported the first mouse model of severe MR ( Figure 11 , 12 ).…”