Transesophageal echocardiography in the diagnosis of thrombosis associated with permanent transvenous pacemaker electrodes

Objectives: We sought to assess the value of transesophageal echocardiography (TEE) in the diagnosis of PM-lead-associated central venous thrombi. Background: Venous thrombosis is not infrequent after pacemaker (PM) or implantable cardioverter-defibrillator (ICD) implantation. Previous incidence studies of thrombosis hove been based on venography or Doppler ultrasound, but the role of TEE has not been systematically evaluated in this setting. Methods: Study group comprised 66 consecutive patients (mean age 64 years, 67% male) referred for implantation of their first PM or ICD and with a successful TEE, transthoracic echocardiography (TTE) and venography at 6 months after implantation. The total number of implanted leads was 110. During the 6 months of clinical follow-up, nuclear ventilation-perfusion scan or spiral computed tomography was performed when symptoms aroused a clinical suspicion of PE. Results: TEE revealed a right atrium (RA) or lower superior vena cava (SVC) thrombus in 6 (9%)patients. These thrombi were not visualized by TTE or venography. Additionally, 12 (20%) patients were found to have venographic subclavian or innominate vein thrombi, but none of those could be diagnosed with TEE. Symptomatic pulmonary embolism (PE) was diagnosed in two and an asymptomatic PE in one individual and two of these occurred among the six patients with a thrombus in TEE. No clinical predictors for thrombosis were found. Conclusions: TEE is an excellent method to visualize electrodes within the RA and proximal SVC. Electrode-associated RA thrombi appear to be relatively common after PM implantation, and they may remain undetectable by venography or TTE. Although these thrombi are mostly asymptomatic, they can give rise to pulmonary embolism and should also be kept in mind in the differential diagnosis of endocarditis. TEE is the method of choice for the diagnosis of these lesions.