Department of Large Animal Internal Medicine, Ghent University, Equine Cardioteam Ghent University, Merelbeke, Belgium.
Equine Vet J. 2019 Sep;51(5):634-640. doi: 10.1111/evj.13073. Epub 2019 Feb 13.
Atrial tachycardia including focal atrial tachycardia and macroreentrant atrial tachycardia (atrial flutter), are occasionally found in horses. Diagnosis, treatment and follow-up of these arrhythmias has been inadequately described.
To describe the findings on surface electrocardiography (ECG), intra-atrial electrogram recording and tissue Doppler imaging (TDI), the response to treatment by transvenous electrical cardioversion (TVEC), and TDI follow-up, of sustained atrial tachycardia in horses.
Case series.
Records from horses with sustained atrial tachycardia treated by biphasic TVEC at Ghent University were reviewed. Horses with atrial fibrillation were not included.
Seven horses with sustained atrial tachycardia were treated with TVEC. In six cases an exercise ECG was available and in 4 a 12-lead ECG had been recorded. The mean bias between atrial cycle length measured from a right atrial intra-atrial electrogram and from TDI ranged between -2 and 3 ms depending on the sampled region. All seven cases converted to sinus rhythm during the first TVEC procedure. TDI showed atrial contractile function recovery similar to cases that were treated for atrial fibrillation. One case developed atrial fibrillation 1 day after TVEC treatment, another case showed recurrence 8 years post conversion. The other five cases were still in sinus rhythm at 9 months - 5 years after TVEC.
Due to the small number of patients, data on recurrence and follow-up of atrial recovery should be interpreted with caution. Since no invasive electrophysiology studies were performed, differentiation between focal atrial tachycardia and atrial flutter remains speculative.
Treatment of focal atrial tachycardia or atrial flutter by TVEC has a very high success rate. Tissue Doppler imaging allows noninvasive measurement of atrial cycle length and suggests reduced atrial function after cardioversion. Long-term prognosis after cardioversion seemed similar compared to horses with atrial fibrillation, although early recurrence (<24 h) occurred in one horse.
局灶性房性心动过速和大折返性房性心动过速（心房扑动）包括在马中偶尔发现的房性心动过速。这些心律失常的诊断、治疗和随访描述不足。
描述持续性房性心动过速在马中的体表心电图（ECG）、心内电图记录和组织多普勒成像（TDI）、经静脉电复律（TVEC）治疗的反应以及 TDI 随访的发现。
病例系列。
回顾了在根特大学接受双相 TVEC 治疗的持续性房性心动过速马的记录。未包括心房颤动的马。
7 匹持续性房性心动过速的马接受了 TVEC 治疗。在 6 例中，可获得运动心电图，在 4 例中，记录了 12 导联心电图。从右心房内心内电图测量的心房周期长度和 TDI 之间的平均偏差在 2 到 3 毫秒之间，具体取决于采样区域。所有 7 例在第一次 TVEC 程序中均转为窦性节律。TDI 显示心房收缩功能恢复与治疗心房颤动的病例相似。1 例在 TVEC 治疗后 1 天出现心房颤动，另 1 例在转换后 8 年复发。其余 5 例在 TVEC 后 9 个月至 5 年内仍处于窦性节律。
由于患者数量较少，应谨慎解释复发和心房恢复随访的数据。由于未进行侵入性电生理研究，因此局灶性房性心动过速和心房扑动之间的鉴别仍存在推测。
TVEC 治疗局灶性房性心动过速或心房扑动的成功率非常高。组织多普勒成像允许非侵入性地测量心房周期长度，并提示电复律后心房功能降低。与患有心房颤动的马相比，电复律后的长期预后似乎相似，尽管 1 匹马在 24 小时内（<24 小时）出现早期复发。
