Both hypothyroidism and hyperthyroidism increase atrial fibrillation inducibility in rats.
Both hypothyroidism and hyperthyroidism increase atrial fibrillation inducibility in rats.
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DOI：
10.1161/circep.113.000502
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发表时间：
2013-10
期刊：
影响因子：
--
通讯作者：
Gerdes AM
中科院分区：
文献类型：
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作者：
Zhang Y;Dedkov EI;Teplitsky D;Weltman NY;Pol CJ;Rajagopalan V;Lee B;Gerdes AM
有证据表明，心脏甲状腺功能减退可能导致心力衰竭（HF）的进展。众所周知，心衰与房颤（AF）的风险增加有关。虽然已经确定甲亢会增加房颤的发病率，但甲状腺功能减退对房颤的影响尚不清楚。本研究探讨了甲状腺功能减退和甲状腺功能亢进等不同甲状腺激素水平对去甲状腺大鼠心房颤动诱导的影响。术后1个月血清证实甲状腺功能减退的去甲状腺大鼠随机分为甲状腺功能减退组（n=9）、甲状腺功能正常组（n=9）和甲状腺功能亢进组（n=9）。大鼠分别接受安慰剂、3.3mg l -甲状腺素（T4）或20 mg T4微丸（60天释放形式）治疗2个月。治疗结束时，确认甲状腺功能减退、甲状腺功能正常和甲状腺功能亢进。甲状腺功能减退动物表现为心脏萎缩，心脏收缩和舒张功能降低，甲状腺功能亢进大鼠表现为心脏肥大，心脏功能增强。甲状腺功能减退和甲状腺功能亢进在心率和心房有效不应期产生相反的电生理变化，但均显著增加AF易感性。甲状腺功能低下组AF发生率为78%，甲状腺功能亢进组为67%，AF持续时间也更长，甲状腺功能正常组为11%（均p<0.05）。甲状腺功能减退增加心房间质纤维化，但连接蛋白43不受影响。在大鼠甲状腺切除术模型中，甲状腺功能减退和甲状腺功能亢进均导致心房颤动易感性增加。我们的研究结果强调，正常的甲状腺激素水平是维持正常的心脏电生理和预防心律失常和房颤所必需的。
Evidence indicates that cardiac hypothyroidism may contribute to heart failure (HF) progression. It is also known that HF is associated with an increased risk of atrial fibrillation (AF). While it is established that hyperthyroidism increases AF incidence, the effect of hypothyroidism on AF is unclear. This study investigated the effects of different thyroid hormone levels, ranging from hypothyroidism to hyperthyroidism on AF inducibility in thyroidectomized rats. Thyroidectomized rats with serum confirmed hypothyroidism 1 month after surgery were randomized into hypothyroid (n=9), euthyroid (n=9) and hyperthyroid (n=9) groups. Rats received placebo, 3.3mg L-thyroxine (T4), or 20 mg T4 pellets (60 day release form) for 2 months, respectively. At the end of treatment, hypothyroid, euthyroid and hyperthyroid status was confirmed. Hypothyroid animals showed cardiac atrophy and reduced cardiac systolic and diastolic function, while hyperthyroid rats exhibited cardiac hypertrophy and increased cardiac function. Hypothyroidism and hyperthyroidism produced opposite electrophysiological changes in heart rates and atrial effective refractory period, but both significantly increased AF susceptibility. AF incidence was 78% in hypothyroid, 67% in hyperthyroid, and the duration of induced AF was also longer, compared with 11% in the euthyroid group (all p<0.05). Hypothyroidism increased atrial interstitial fibrosis, but connexin 43 was not affected. Both hypothyroidism and hyperthyroidism lead to increased AF vulnerability in a rat thyroidectomy model. Our results stress that normal thyroid hormone levels are required to maintain normal cardiac electrophysiology and prevent cardiac arrhythmias and AF.