Avaliação radiográfica, ecocardiográfica e hemogasométrica arterial de cães com hipertensão pulmonar secundária à degeneração mixomatosa valvar mitral

Abstract

Myxomatous mitral valve degeneration (MMVD) is the most common acquired heart disease in dogs. It is associated with systolic mitral regurgitation and increased pressure in the left atrium (LA) with the possibility of developing pulmonary arterial hypertension (PAH). Cardiac catheterization is considered the gold standard, however the echocardiogram is the non-invasive method commonly used in Veterinary Medicine to diagnose the probability of PAH. Few current literature associate radiographic and blood gas analysis findings of dogs with PAH secondary to MMVD. In the search for associations between diagnostic tests to define the prognosis of the disease and the quality of life of the patients, 56 dogs with echocardiographic evidence of MMVD from the clinical routine of the cardiology service of the Veterinary Hospital of the Veterinary School of the Federal University of Minas were evaluated General. The dogs were divided into a control group with peak speed of tricuspid valve regurgitation (TR) <2.5 m / s and pressure gradient <30 mmHg, light group from 2.5 to <3.5 m / s and 30 to < 50 mmHg, moderate group of 3.5 to 4.3 m / s and 50 to 75 mmHg and severe> 4.3 m / s> 75 mmHg. A higher relative frequency of dogs with MMVD in stages B2 and C was observed, mainly in the moderate and severe groups. There was an increase in the LA by the linear echocardiographic measurement of the relationship between the LA diameter and the aorta diameter (LA / Ao) between the control group and the others. The left atrial size (VLAS) vertebral radiographic method demonstrated good repeatability and a significant association with AE / Ao (p <0.001) and TR pressure gradient (p = 0.001), showing a significant difference between the control and severe groups . The vertebral heart size (VHS) method and its short axis (Sax) demonstrated greater measures when associated with an increase in left ventricular diastolic diameter normalized by weight (p <0.001 and p = 0.001, respectively) and more advanced stages of MMVD (p <0.001). The VLAS had a predictive value in the probability of PAH of 2.65 v (p = 0.032) and the Sax of 5.26 v (p = 0.015), both with 54% sensitivity, 85% specificity and with approximate risk factors (Odds ratio = 2.88 and 2.89, respectively). The values of REVDA (10.38 cm2 / m2 ± 3.2, p <0.001) and FAC (32, 87% ± 9.51, p = 0.004) showed a significant difference in the severe group, with the cutoff value of 32.42 FAC (p = 0.023) in the prediction of probable PAH (sensitivity 50%; specificity 78%). Radiographic findings of increased sternal contact and an image similar to the inverted “D” were more frequent in the severe group. The radiographic estimation method 3/5 - 2/5 should be carefully evaluated in animals with MMVD because it is underestimated when associated with an enlarged left ventricle (p = 0.202). The blood gas analysis data showed no statistical difference between the groups, except for bicarbonate (HCO3). However, a reduction in pH was observed due to the increase in the partial pressure of arterial carbon dioxide (PaCO2) in the moderate and severe groups, with a consequent increase in HCO3 as a compensatory mechanism. The relationship between partial arterial oxygen pressure and inspired oxygen fraction (PaO2 / FiO2) was lower, while lactate showed higher values in more advanced stages of MMVD. Therefore, radiographic and hemogasometric information, associated with echocardiography, can be used to monitor and guide therapeutic decisions in dogs with probability of PAH secondary to MMVD.