A 72-year-old female patient with a 5-year history of heart failure presented with recurrent hospitalizations due to dyspnea. Electrocardiogram ( Figure 1 ,A ) demonstrated sinus rhythm with complete left bundle branch block (CLBBB) and a QRS duration of 189 ms. Echocardiography revealed a left ventricular ejection fraction (LVEF) of 27%. The diagnosis was established as HF with NYHA class III and complete left bundle branch block.

(A)Preoperative electrocardiogram; (B) Postoperative electrocardiogram.

Following comprehensive evaluation of the patient’s medical history and diagnostic findings, and after obtaining informed consent, Left Bundle Branch-Optimized Cardiac Resynchronization Therapy Defibrillator (LOT-CRTD) implantation was planned. The procedure commenced with a single right femoral vein puncture for temporary pacemaker placement, serving as protective measure against potential transient third-degree atrioventricular block during lead manipulation that might compromise the right bundle branch. Subsequently, under fluoroscopic guidance, 4 venous access points were established through left axillary vein punctures to facilitate device implantation.

One venous access served as the LV epicardial electrode pathway, The LV lead delivery system (Attain Command, Medtronic, USA) was used as the supporting platform to advance the LV lead (4396, 5.7F, Medtronic, USA) over a guidewire (Runthrough NS Floppy, 0.014-inch, TERUMO, Japan). For the second access, a 9F peel-away sheath (Abbott, USA) was introduced over a hydrophilic guidewire (GUIND WIRE, 0.035-inch, TERUMO, Japan), through which a novel coronary sinus venography balloon catheter (Lee’s catheter, 6F, APT Medical, China) was positioned within the coronary vein. Balloon occlusion angiography at the coronary sinus (CS) ostium using Lee’s catheter delineated the anatomy of the CS trunk and its branches, identifying the lateral vein as the target vessel ( Figure 2 ,A ). The lateral vein exhibited an acute angle at its origin from the great cardiac vein with tortuous proximal course, rendering conventional shaped percutaneous transluminal coronary angioplasty (PTCA) guidewire navigation unsuccessful. The BMW technique was employed for LV lead implantation utilizing a dual-catheter “bipedal approach”: the “left leg” constituted Lee’s catheter while the “right leg” comprised the working guidewire and electrode. Initial balloon occlusion at the great cardiac vein distal to the lateral vein ostium ( Figure 2 ,B) failed to facilitate guidewire advancement ( Figure 2 ,C). After recognizing suboptimal occlusion position relative to the lateral vein origin, proximal repositioning of Lee’s catheter was performed ( Figure 2 ,D). Subsequent guidewire manipulation successfully achieved distal lateral vein access ( Figure 2 ,E). Following balloon deflation, the LV lead was advanced over the guidewire to the distal lateral vein ( Figure 2 ,F), demonstrating acceptable pacing parameters (threshold: 0.75V, impedance: 589Ω).

(A)Coronary sinus venography; (B) Initial balloon occlusion attempt with distal positioning bias; (C) Failed guidewire advancement to venous distal segment during first occlusion; (D) Catheter retraction followed by secondary occlusion attempt; (E) Optimal secondary occlusion enabling successful guidewire deployment to venous distal segment; (F) Balloon removal with subsequent left ventricular lead placement along the guidewire.

Subsequently, the left bundle branch electrode (3830, 4.1F, Medtronic, USA) was sequentially implanted into the left posterior fascicular area (pacing threshold: 0.5 V, sensing: 13.1 mV, impedance: 665 Ω), followed by placement of the atrial electrode (2088TC, 6F, Abbott, USA) in the right atrial appendage (pacing threshold: 0.7 V, sensing: 1.8 mV, impedance: 475 Ω), and the right ventricular defibrillation electrode (Model 6935, 8.6F, Medtronic, USA) in the low septal region of the right ventricle (pacing threshold: 0.6 V, sensing: 10.4 mV, impedance: 472 Ω). Postoperative electrocardiogram ( Figure 1 ,B) demonstrated a reduction in QRS complex duration to 118 ms.