Eletrocardiografia holter em cães submetidos ao teste de estimulação com hormônio adrenocorticotrófico

Abstract

Given that glucocorticoids indirectly stimulate the release of catecholamines by the adrenals, it was hypothesized that there may be, during the stimulation test with synthetic adrenocorticotropic hormone (STACTH), some degree of adrenergic discharge. Thus, through a prospective clinical trial, the 8-hour Holter data obtained from six dogs (3 males and 3 females, 11.1±7.4 kg and 9.7±2.2 years), suspected and/or patients with pituitary-dependent hypercortisolism (PDH), without preexisting endocrinopathies were evaluated. It is noteworthy that each animal constituted control of itself by undergoing both the conventional STACTH and a simulation of the referred test using saline solution (placebo). HR variability [SDNN (ms), SDANN (ms), rMSSD (ms), NN50 (bpm) and pNN50 (%)] as well as minimum, maximum and average HR (bpm) obtained two hours after Holter placement (T0) and one (T1), two (T2) and three hours (T3) after the application of ACTH or placebo, in addition to heart rate and ectopia were compared. No differences in HR values and variability indices were identified during STACTH and placebo, indicating that synthetic ACTH was not able to increase sympathetic tone in the heart. Despite this, one of the dogs (16.6%) had 117 ventricular ectopias on T1 and 183 on T2 after STACTH, as well as an accelerated idioventricular rhythm (AIVR) (>2 minutes) immediately after the application of intravenous ACTH. The results obtained here, although pointing out that synthetic ACTH appears not to be able to cause a significant change in sympathetic tone in the heart, alert to the possibility of inducing the appearance of AIVR.