To preserve the benefit of atrial sensing without the need to implant an additional lead, a single-lead ICD system with a floating atrial dipole (VDD or DX ICD) has been developed . The VDD ICD system offers an additional atrial intracardiac electrogram, with early detection of atrial arrhythmias, possibly improved supraventricular tachycardia discrimination and AV-sequential pacing in single-lead devices. Moreover, it can be upgraded to a two-lead cardiac resynchronization therapy (CRT)-DX system in the case of stable, long-term atrial sensing and a developing need for CRT. The feasibility of the VDD ICD system in the case of LSCV may be of particular interest.
The incidence of a persistent LSVC has been reported in up to 0.66% of ICD recipients . Lead placement may be technically challenging, especially in the case of absent right superior vena cava. Although most cases can be accomplished with a reliable outcome , in some patients implantation of alternative systems should be considered [3, 4].
The current case represents an optimal candidate for a VDD ICD: slightly prolonged AV conduction with a potential need for AV-synchronous pacing and/or upgrade to CRT in the future and a greatly elevated risk of stroke . However, implantation of more complex leads—such as an ICD lead—is often technically challenging in patients with cardiac anatomic variants. To the best of the authorsʼ knowledge, this is the first report demonstrating the feasibility of the VDD ICD system in the case of LSCV.