Department of Neurology, University of California, Davis, Sacramento, California, USA.
Epilepsia. 2011 Nov;52(11):2105-11. doi: 10.1111/j.1528-1167.2011.03262.x. Epub 2011 Sep 11.
Cardiac arrhythmias and respiratory disturbances have been proposed as likely causes for sudden unexpected death in epilepsy. Oxygen desaturation occurs in one-third of patients with localization-related epilepsy (LRE) undergoing inpatient video-electroencephalography (EEG) telemetry (VET) as part of their presurgical workup. Ictal-related oxygen desaturation is accompanied by hypercapnia. Both abnormal lengthening and shortening of the corrected QT interval (QTc) on electrocardiography (ECG) have been reported with seizures. QTc abnormalities are associated with increased risk of sudden cardiac death. We hypothesized that there may be an association between ictal hypoxemia and cardiac repolarization abnormalities.
VET data from patients with refractory LRE were analyzed. Consecutive patients having at least one seizure with accompanying oxygen desaturation below 90% and artifact-free ECG data were selected. ECG during the 1 min prior to seizure onset (PRE) and during the ictal/postictal period with accompanying oxygen desaturation below 90% (DESAT) was analyzed. Consecutive QT and RR intervals were measured. In the same patients, DESAT seizures were compared with seizures without accompanying oxygen desaturation below 90% (NODESAT). For NODESAT seizures, QT and RR intervals for 2 min after seizure onset were measured.
Thirty-seven DESAT seizures were analyzed in 17 patients with localization-related epilepsy. A total of 2,448 QT and RR intervals were analyzed during PRE. During DESAT, 1,554 QT and RR intervals were analyzed. Twelve of the 17 patients had at least one NODESAT seizure. A total of 19 NODESAT seizures were analyzed, including 1,558 QT and RR intervals during PRE and 3,408 QT and RR intervals during NODESAT. The odds ratio for an abnormally prolonged (>457 ms) QTcH (Hodges correction method) during DESAT relative to PRE was 10.64 (p < 0.0001). The odds ratio for an abnormally shortened (<372 ms) QTcH during DESAT relative to PRE was 1.65 (p < 0.0001). Seizure-related shortening and prolongation of QTc during DESAT were also observed when Fridericia correction of the QT was applied. During DESAT seizures, the mean range of QT values (QTr) (61.14 ms) was significantly different from that during PRE (44.43 ms) (p = 0.01). There was a significant association between DESAT QTr and oxygen saturation nadir (p = 0.025) and between DESAT QTr and duration of oxygen desaturation (p < 0.0001). Both QTcH prolongation and shortening also occurred with NODESAT seizures. A seizure-associated prolonged QTcH was more likely during DESAT than NODESAT, with an odds ratio of 4.30 (p < 0.0001). A seizure-associated shortened QTcH was more likely during DESAT than NODESAT with an odds ratio of 2.13 (p < 0.0001).
We have shown that the likelihood of abnormal QTcH prolongation is increased 4.3-fold with seizures that are associated with oxygen desaturation when compared with seizures that are not accompanied with oxygen desaturation. The likelihood of abnormally shortened QTcH increases with seizures that are accompanied by oxygen desaturation with an odds ratio of 2.13 compared with that in seizures without desaturations. There is a significant association between the depth and duration of oxygen desaturation and QTr increase. These findings may be related to the pathophysiology of SUDEP.
心律失常和呼吸障碍被认为是癫痫患者意外猝死的可能原因。在接受住院视频-脑电图（EEG）遥测（VET）作为术前评估的一部分的局灶性相关癫痫（LRE）患者中，有三分之一的患者会出现氧饱和度下降。与癫痫发作相关的氧饱和度下降伴有高碳酸血症。已有报道称，癫痫发作时心电图（ECG）的校正 QT 间期（QTc）异常延长和缩短均与癫痫发作有关。QTc 异常与心脏性猝死风险增加有关。我们假设癫痫发作时的低氧血症和心脏复极异常之间可能存在关联。
分析了难治性 LRE 患者的 VET 数据。选择了至少有一次伴有氧饱和度低于 90%且 ECG 数据无干扰的癫痫发作的连续患者。分析了发作前 1 分钟（PRE）和伴有氧饱和度低于 90%的癫痫发作/癫痫后期间（DESAT）的 ECG。测量了连续的 QT 和 RR 间隔。在同一患者中，将 DESAT 癫痫发作与不伴有氧饱和度低于 90%的癫痫发作（NODESAT）进行比较。对于 NODESAT 癫痫发作，测量了发作后 2 分钟的 QT 和 RR 间隔。
分析了 17 例局灶性相关癫痫患者的 37 次 DESAT 癫痫发作。在 PRE 期间共分析了 2448 个 QT 和 RR 间隔。在 DESAT 期间，共分析了 1554 个 QT 和 RR 间隔。17 名患者中有 12 名至少有一次 NODESAT 癫痫发作。共分析了 19 次 NODESAT 癫痫发作，包括 PRE 期间的 1558 个 QT 和 RR 间隔和 NODESAT 期间的 3408 个 QT 和 RR 间隔。与 PRE 相比，DESAT 时异常延长（>457ms）QTcH（Hodges 校正法）的优势比为 10.64（p<0.0001）。DESAT 时异常缩短（<372ms）QTcH 的优势比为 1.65（p<0.0001）。当应用 Fridericia 校正 QT 时，也观察到癫痫发作时 DESAT 期间 QTc 的缩短和延长。在 DESAT 癫痫发作期间，QT 值（QTr）的平均范围（61.14ms）与 PRE（44.43ms）明显不同（p=0.01）。DESAT QTr 与氧饱和度最低点之间存在显著关联（p=0.025），与氧饱和度下降时间之间也存在显著关联（p<0.0001）。NODESAT 癫痫发作也会出现 QTcH 延长和缩短。与 NODESAT 相比，DESAT 时癫痫相关的 QTcH 延长更有可能发生，优势比为 4.30（p<0.0001）。与 NODESAT 相比，DESAT 时癫痫相关的 QTcH 缩短更有可能发生，优势比为 2.13（p<0.0001）。
我们已经证明，与不伴有氧饱和度下降的癫痫发作相比，与氧饱和度下降相关的癫痫发作时 QTcH 延长的可能性增加了 4.3 倍。伴有氧饱和度下降的癫痫发作时 QTcH 缩短的可能性增加，与不伴有氧饱和度下降的癫痫发作相比，优势比为 2.13。氧饱和度下降的深度和持续时间与 QTr 增加之间存在显著关联。这些发现可能与 SUDEP 的病理生理学有关。
