Laboratory of Comparative Cardiology, Department of Veterinary Medicine, Federal University of Paraná (UFPR), Rua dos Funcionários, 1540, Curitiba, PR, 80035-050, Brazil.
Vet Res Commun. 2023 Jan;47(1):121-130. doi: 10.1007/s11259-022-09936-1. Epub 2022 May 16.
Hypercortisolism is one of the most common endocrine diseases in dogs. In humans, it is clearly associated with a higher risk of cardiovascular events, but studies in dogs are scarce. To investigate the arrhythmogenic risk of dogs with naturally-occurring hypercortisolism (NOHC), indices of variability and instability of the QT interval were retrospectively studied in 38 dogs with NOHC and prospectively studied in 12 healthy dogs: variance (QTv), total instability (TI), short-term (STI) and long-term (LTI), and mean (QTm). Except for QTm, all parameters studied were higher in the NOHC group than in the control group. In addition, STI and QTv showed moderate positive correlation with left ventricle wall thickness. The NOHC group was subdivided according to cortisol suppression pattern in the low-dose dexamethasone suppression test. All electrocardiographic indices of partial and absent suppression patterns were numerically higher than healthy dogs. QTv and TI were lower in the control group than in both NOHC subgroups. LTI and STI were lower in the CG than in the group with the partial suppression pattern. There was no statistical difference between sex groups in any of the electrocardiographic parameters studied. This result might indicate that the etiology of NOHC, and its consequent influence on hypothalamus-pituitary-adrenal axis could interfere on the heterogeneity of ventricular repolarization parameters in different ways, especially in the short-term and the long-term stability; however further studies are necessary to understand the role of cortisol on electrical instability in dogs.
库欣综合征是犬最常见的内分泌疾病之一。在人类中，它与心血管事件风险的增加明显相关，但犬的研究很少。为了研究自发性库欣综合征（NOHC）犬的致心律失常风险，回顾性研究了 38 只 NOHC 犬的 QT 间期变异性和不稳定性指数，并前瞻性研究了 12 只健康犬：变异性（QTv）、总不稳定性（TI）、短期（STI）和长期（LTI）和平均（QTm）。除了 QTm 之外，NOHC 组的所有研究参数均高于对照组。此外，STI 和 QTv 与左心室壁厚度呈中度正相关。根据低剂量地塞米松抑制试验中的皮质醇抑制模式，将 NOHC 组进一步细分。部分和完全抑制模式的所有心电图指数均高于健康犬。与 CG 相比，NOHC 组的 QTv 和 TI 更低。与部分抑制模式相比，CG 的 LTI 和 STI 更低。在任何研究的心电图参数中，性别组之间均无统计学差异。这一结果可能表明，NOHC 的病因及其对下丘脑-垂体-肾上腺轴的影响可能以不同的方式干扰心室复极参数的异质性，尤其是在短期和长期稳定性方面；然而，还需要进一步的研究来了解皮质醇在犬心脏电不稳定中的作用。
