Abstract：
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.
摘要：
皮质醇增多症是犬中最常见的内分泌疾病之一。在人类中,它显然与心血管事件的高风险有关，但是对狗的研究很少。探讨自然发生皮质醇增多症(NOHC)犬的致心律失常风险,在38只患有NOHC的狗中回顾性研究了QT间期的变异性和不稳定性指数，并在12只健康狗中进行了前瞻性研究：方差（QTv），总不稳定性(TI)，短期(STI)和长期(LTI)，和平均值（QTm）。除了QTm,NOHC组研究的所有参数均高于对照组.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对NOHC组进行细分。部分抑制模式和无抑制模式的所有心电图指标在数字上都高于健康犬。对照组的QTv和TI均低于两个NOHC亚组。CG中的LTI和STI低于部分抑制模式组。在研究的任何心电图参数中，性别组之间没有统计学差异。这一结果可能表明NOHC的病因，其对下丘脑-垂体-肾上腺轴的影响可能以不同方式干扰心室复极参数的异质性，特别是在短期和长期稳定性;然而，进一步的研究是必要的，以了解皮质醇对狗的电不稳定性的作用。
