Função miocárdica pela ecocardiografia feature tracking bidimensional em cães submetidos à anestesia para procedimentos cirúrgicos ortopédicos

Abstract

Dogs locomotor system is often affected by orthopedic diseases and complex anesthesicsurgical procedures are commonly necessary to treat these conditions. It is known that several anesthetics used in dogs have depressor effects on the cardiovascular system, leading to changes in the blood pressure, cardiac output, cardiac rhythm and myocardial function. The present study evaluated left ventricular myocardial function in dogs submitted to different anesthetic protocols for orthopedic surgical procedures using conventional echocardiogram and two-dimensional feature tracking. Twenty-two dogs were divided into three groups according to the medications used during anesthesia: FOPI (phenothiazines, opioids, propofol, isoflurane), FOPBI (phenothiazines, opioids, propofol, benzodiazepines, isoflurane) and OPI, propofol, isoflurane). Four evaluations were performed in each animal: before anesthesia (time 1-T1), immediately after (time 2-T2), 12 hours after anesthesia (time 3-T3) and with 10 days (time 4-T4). Conventional echocardiographic variables were obtained through twodimensional, M-mode and Doppler modes (color, pulsed, continuous and tissue), besides the strain and strain rate global variables in the longitudinal, circumferential and radial directions. Overall, there was no significant difference in conventional echocardiographic variables when compared to anesthesia groups. In the analyzes of each group, the variables index of final systolic and diastolic volume, E / A ratio of the mitral flow, E '/ A' ratio and ejection fraction presented differences between the evaluation times, although the results remained within the values of reference for the species. The overall mean of the longitudinal and circumferential strain rates did not show any difference between the anesthetic groups used, although there was a significant reduction in the values found for circumferential strain rate in the period after anesthesia in dogs of group FOPI (T2: -0.83 ± 0, 29: T3: -1.06 ± 0.26, p = 0.0292) and FOPBI (T2: -0.74 ± 0.41, T4: -1.07 ± 0.31, p = 0.0037). In the analyzes between the groups, there was difference in radial strain in the fourth evaluation (FOPI: 14.15 ± 6.98, FOPBI: 24.60 ± 5.74, OPI: 13.94 ± 6.58, p = 0.0386). Strain rate was reduced in the second evaluation of the dogs of group FOPI (T2: 1.22 ± 0.42, T3: 1.57 ± 0.29, p = 0.0266) and in the third evaluation of groups FOPBI (T3: 1.48 ± 0.44, T4: 2.28 ± 0.55, p = 0.0012) and OPI (T1: 1.73 ± 0.23, T3: 1.34 ± 0.38; = 0.0291). Although transient reduction in myocardial function has been observed in anesthetized dogs, there was no significant myocardial dysfunction. In the interobserver evaluation, the variability was low for strain and strain rate longitudinal and circumferential and moderate for radial. Thus, it is concluded that (1) anesthesia causes a transient reduction in left ventricular function in dogs due to the depressor effects of drugs on the cardiovascular system; and that (2) two-dimensional feature tracking echocardiography seems is sensitive in the determination of myocardial function in dogs undergoing anesthesia.