Cine-MRI assessment of cardiac function in mice anesthetized with ketamine/xylazine and isoflurane

Abstract

Since small-animal MRI generally requires anesthesia, the effect of the anesthetic regimen on the explored organ(s) has to be taken into account for study interpretation. In this work, we assess the influence of ketamine/xylazine and isoflurane anesthesia on left-ventricular (LV) function in the mouse in vivo by cine-MRI. Three groups of animals were anesthetized with ketamine/xylazine (n = 13) and two different concentrations of isoflurane (1.25%, n = 12 and 2.00%, n = 12) delivered in O2/N2O mix. Long- and short-axis cine-MRI was performed to measure end-diastolic volume, stroke volume, ejection fraction and LV wall thickness. Ketamine/xylazine significantly reduced heart rate, cardiac output and wall thickness, but increased stroke volume and end-diastolic volume compared with both isoflurane groups. No differences across all groups were observed in ejection fraction or systolic wall thickening. Breath rate under isoflurane was significantly lower and concentration dependent, whereas heart function was independent of concentration in all measured parameters. These findings are in agreement with echocardiography and catheterization studies. Isoflurane is advantageous for MR studies because it better maintains cardiac function. Taking into account previously obtained myocardial perfusion measurements, isoflurane concentration should, however, be maintained at the minimum required for a stable sleep even if cardiac function is unaffected by higher isoflurane concentrations.

Dystrophin-deficient cardiomyopathy in mouse: Expression of Nox4 and Lox are associated with fibrosis and altered functional parameters in the heart

“…[31] The additional capability of directly measuring percent ejection fraction in the 2D parasternal long axis allows high frequency echocardiography to be used alongside other newer imaging modalities such as 3D echo and MRI. [32], [33], [34] Our histological results are in agreement with previous studies demonstrating patchy fibrosis in the ventricles of mdx mice. [15], [35], [36], [37], [38] The loss of functional muscle tissue and resulting fibrosis can lead to decreased cardiac systolic and diastolic function.…”

Cardiac magnetic resonance imaging in small rodents using clinical 1.5T and 3.0T scanners

“…Studies have been performed using several anesthetics, but inhaled anesthetics, such as isoflurane, have been shown to be most effective for maintaining sedation throughout the CMR exam without significant effects on cardiac function (21,22). In general, animals are induced in a closed container using 3-5% isoflurane.…”

Impact of Anesthesia on Echocardiographic Evaluation of Systolic and Diastolic Function in Rats

“…Therefore the choice of anesthetic agent has the potential to significantly alter echocardiographic parameters. Despite the reported differential effects of anesthetic agents on cardiac function and echocardiograms in mice ( [18][19][20][21][22][23][24][25] ) , much less is known about the impact of the choice of the anesthetic agent on the echocardiogram of sedated healthy or sick rats, especially if the animals suffer from a cardiac disease that is significantly affecting pre-load and afterload. Therefore the present study was performed to assess the differential impact of two types of anesthetic regimens (intraperitoneal ketamine-xylazine or inhaled isoflurane) on basic echocardiographic measurements 1) in healthy male adult rats and 2) in rats suffering from chronic aortic valve regurgitation (AR).…”