A man in his early 70s with a history of permanent atrial fibrillation treated with atrioventricular junction ablation and biventricular pacemaker implantation was hospitalized with decompensated heart failure and acute kidney injury. His history was notable for nonischemic cardiomyopathy with ejection fraction of 40% and idiopathic pulmonary fibrosis, for which he underwent single-lung transplant 9 years prior. Following diuresis and medical optimization, repeated echocardiogram showed a newly depressed ejection fraction (30%). His electrocardiogram (ECG) was notable for alternating QRS morphologies (Figure 1A). The left ventricular (LV) pacing vector was programmed from LV tip to right ventricular (RV) lead ring. During pacemaker threshold testing, a change in QRS morphology was observed as the output was reduced (Figure 1B). Chest radiography revealed severe right pulmonary fibrosis leading to ipsilateral mediastinal shift and pacemaker lead position unchanged from implantation.

一名 70 岁出头的男性有永久性房颤病史，接受房室交界处消融和双心室起搏器植入治疗，因失代偿性心力衰竭和急性肾损伤住院。他的病史值得注意的是射血分数为 40% 的非缺血性心肌病和特发性肺纤维化，为此他在 9 年前接受了单肺移植。在利尿和药物优化后，重复超声心动图显示射血分数新降低（30%）。他的心电图 (ECG) 以交替 QRS 形态学 (图 1A) 着称。左心室 (LV) 起搏矢量从 LV 尖端编程到右心室 (RV) 导联环。在起搏器阈值测试期间，随着输出的减少，观察到 QRS 形态的变化（图 1B）。