Successful implantation of a leadless pacemaker in a patient with complete atrioventricular block and congenital absence of superior vena cava: a case report

Background Congenital absence of superior vena cava (CASVC) is an extremely rare vascular anomaly often associated with conduction disturbances which makes implantation of a pacemaker difficult. We report a case of pacemaker implantation in a patient presenting with complete atrioventricular block (c-AVB) with bilateral absence of the SVC. Case summary A 68-year-old man who had experienced dyspnoea on exertion by c-AVB was admitted to our hospital for treatment and management. Permanent pacemaker insertion was initially planned; however, an endocardial pacemaker lead could not be implanted in the right atrium. Computed tomography scan with contrast revealed that the venous blood from the upper half of the body flowed into the inferior vena cava via the azygos vein. Due to the difficulty of inserting an endocardial lead from the subclavian vein, a leadless pacemaker (LP) was implanted instead via the femoral vein. Discussion This is the first case of an LP implantation in a patient presenting with c-AVB with CASVC. Confirmation of blood vessel anatomy to rule out CASVC is necessary prior to pacemaker implantation when abnormal venous anatomy is suspected.