A 3-year-old female spayed indoor/outdoor Siamese cat was diagnosed with cytauxzoonosis and irregular heart rhythm was appreciated during a physical examination. On electrocardiogram, the cat had an average ventricular rate of 144 beats/min with Wenckebach type (Mobitz type I) atrioventricular block. The QRS complexes of sinus conducted beats had left anterior fascicular block morphology, they were followed by two subsequent beats presented with a prolonged P-R interval and QRS conducted with a left bundle branch block. The finding of alternating left anterior fascicular block and left bundle branch block along with atrioventricular block is consistent with trifascicular block. No structural heart changes were noted on echocardiography. Approximately 48 h after presentation to the emergency service, the cat acutely decompensated and spontaneously died.

一只 3 岁雌性室内/室外绝育暹罗猫被诊断出患有细胞动物寄生虫病，体检时发现心律不齐。在心电图上，这只猫的平均心室率为 144 次/分钟，伴有 Wenckebach 型（Mobitz I 型）房室传导阻滞。窦性传导搏动的 QRS 波群呈左前束状传导阻滞形态，随后的两次搏动表现为 PR 间期延长，QRS 传导伴左束支传导阻滞。左前分支传导阻滞和左束支传导阻滞交替伴房室传导阻滞的发现与三分支传导阻滞一致。超声心动图未发现心脏结构变化。就诊后约 48 小时，