Persistent left superior vena cava (PLSVC) is encountered occasionally during angiographic
procedures. It usually coexists with right superior vena cava and drains to the right atrium
through the coronary sinus, but multiple variations are described. Although PLSVC is extensively
reported in the literature, there are very few articles addressing right heart catheterization in patients
with isolated PLSVC. We present a patient with absent right superior vena cava and PLSVC draining
to a dilated coronary sinus diagnosed during right heart catheterization in the setting of pulmonary
hypertension. We were able to safely complete the procedure through the right internal jugular vein.
Transthoracic echocardiography and chest CT scan were consistent with this finding. Although
clinically silent most of the time, undiagnosed PLSVC can lead to catastrophic consequences when
the patient undergoes invasive procedures. If PLSVC is suspected, the anatomy of the thoracic venous
system must be identified before invasive cardiac procedures.