Central venous catheters (CVCs) are widely used for therapeutic purposes and to measure hemodynamic variables that cannot be recorded from a peripheral vein. However, the method can involve complications. In cardiac surgery, CVCs are electively placed in the right internal jugular vein but there is little information on deep venous thrombosis (DVT) in catheterized veins (CVC-related DVT) or on secondary pulmonary embolism (PE). The impact of CVC-related DVT and PE in cardiac surgery and measures to prevent PE were assessed. We used ultrasonography (US) to check the point of insertion of CVC in 815 patients in the intensive cardiac rehabilitation unit after heart surgery. In this series, 386 patients (48%) had CVC-related DVT; those already receiving anticoagulant, and considered at low risk, continued that therapy, while those taking an antiplatelet agent (aspirin 100 mg daily) but deemed at high risk of PE from the US findings were given an anticoagulant instead. Only patients with CVC-related DVT at low risk of PE continued taking aspirin. At 3 months, there were no cases of PE among patients receiving an anticoagulant, but six on antiplatelet had non-fatal PE. The prevalence of PE in the whole series of 815 patients was 0.7%. CVC-related DVT is a frequent complication of heart surgery. Anticoagulant therapy started early does not prevent thrombus formation but probably prevents PE, whereas antiplatelet gives no such protection. Sonographic screening of the CVC removal in intensive care unit may be useful for avoiding PE after CVC-related DVT.