More than 235.500 cardiac pacemakers and cardioverter-defibrillators are implanted in the US every year, with an estimated 25,000 new implants in Brazil. Despite its proven clinical effectiveness and efficacy for a number of clinical conditions such as arrhythmias, the number of adverse events in the post-implant period remains substantial. Among these complications, venous obstructions occurs anywhere between 14% and 64% of all patients, causing devastating consequences such as upper extremity deep venous thrombosis and pulmonary embolism, ultimately leading to either significant impairment or death. Although retrospective studies have demonstrated the high incidence of these complications, as a consequence of a paucity of reliable registries we know next to nothing regarding how these venous lesions may influence the clinical outcome and mortality of patients, whether laboratorial markers may contribute to the early diagnosis of venous thrombosis and its complications, and about properties of diagnostic imaging for the identification of thromboembolic complications after permanent transvenous leads implantation.