Introducere: Persistent left superior vena cava (PLSVC) is found in 0.3% of normal people, while the absence of right superior vena cava (ARSVC) is a very rare con-genital malformation (found in 0.1% of the normal population). Since it is completely asymptomatic, this venous malformation is most often discovered inciden-tally during invasive procedures such as cardiac device implantation or central venous catheter insertion.

Methods: We report the case of a 64 year old male, with a history of ischemic dilated cardiomyopathy, who re-cently had an episode of monomorphic ventricular tachycardia with haemodynamic compromise and re-quired electrical cardioversion before admission. The patient was a smoker, had arterial hypertension and dyslipidemia. He had NYHA class II heart failure symp-toms but no heart failure sign. The electrocardiogram shows a record of sinus rhythm, narrow QRS complex, low voltage in extremity leads and negative T waves in lateral leads. The transthoracic echocardiogram show-ed enlarged heart chambers, severely reduced ejection fraction and the dilation of the coronary sinus.

Results: During the same admission he was scheduled for an cardioverter-defibrillator implantation. Under fluoroscopy, the ICD lead was inserted through the cephalic vein into, what seemed to be the right atrium, but the lead couldn’t be advanced into the right ven-tricle. After the fluoroscopy incidence was changed, it could be noticed that the lead had an extra-cardiac trajectory, being placed into a collateral vein. The lead was extracted and contrast was injected into the left subclavian vein, revealing persistent left superior vena cava draining into the coronary sinus and absence of the right superior vena cava. Therefore, the defibrillator lead was inserted through the LSVC and fixed to the right ventricle septum.

Conclusions: PLSVCC is the most frequent thoracic venous malformation, in 80-90% of the cases coexis-ting with a right superior vena cava. Additionally, it is associated with a high incidence of atrial septal defect, arrhythmia, conduction disturbances and even tetra-logy of Fallot. The patient we presented had isolated PLSVC which an increased venous blood flow causing significant enlargement of the coronary sinus. Even though PLSVC with absent RSVC doesn’t have a sig-nificant haemodinamic impact, knowing about this ve-nous anomaly is useful not only to cardiac surgeons, but also to cardiac devices implanting physicians and those performing anesthesia maneuvers.