CONGRESS ABSTRACT

Introduction: Nowadays, pacemaker (PM) therapy remains associated with considerable peri- and post-procedural complications. Blind puncture of the subclavian vein for PM lead insertion is a routine procedure, but it carries the risk of potentially life-threatening complications, including pneumothorax, arteriovenous fistula, and injury or perforation of the subclavian artery, vein, or left internal mammary artery (LIMA). Case Presentation: A 48-year-old woman with no prior cardiovascular history presented to the emergency department with frequent lipothymic episodes and dizziness. ECG revealed a 2:1 atrioventricular block, while transthoracic echocardiogram (TTE) showed normal biventricular function and excluded structural heart disease. After three unsuccessful attempts at left subclavian venous puncture and several lead repositioning attempts due to unstable pacing and sensing thresholds, a dual-chamber pacemaker was implanted. Immediately following the procedure, the patient developed severe hypotension, requiring pharmacological support, with labile stabilization of blood pressure. Chest fluoroscopy indicated hemopneumothorax, while TTE ruled out pericardial effusion. The initial diagnosis was active bleeding, prompting urgent femoral angiography. The angiography revealed active contrast medium extravasation from the proximal segment of the LIMA, leading to a massive hemothorax, with no other active bleeding sources identified. Endovascular repair was performed using two covered stents (2.5 x 23 mm and 3.0 x 13 mm), and contrast injection confirmed occlusion of the arterial hole. Despite this intervention, the patient required chest drain placement and blood transfusions. Due to the high risk of further bleeding and the secondary role of the LIMA, dual-antiplatelet therapy was not initiated. Comment: Inadvertent perforation of the LIMA during a blind approach to the subclavian vein for PM implantation is an extremely rare but potentially life-threatening complication. Prompt identification of the bleeding source and immediate intervention are crucial to prevent mediastinal and thoracic hematomas, which can rapidly worsen hemodynamic instability. Covered stent deployment offers a rapid and effective solution, particularly in hemodynamically unstable patients. Endovascular repair should be considered the first option in critical patients, especially when the procedure can be performed by an experienced operator in peripheral interventions.