Quadripolar left ventricle only single lead pacing in a patient with a tricuspid mechanical valve: A less invasive approach

Transvenous right ventricular (RV) endocardial lead placement is the conventional practice in clinical pacing. In some situations, as in the presence of prosthetic tricuspid valve, the inaccessibility to the RV makes the permanent pacing through a coronary sinus (CS) lead placement a good alternative [, ]. There are also described cases of dual-site ventricular pacing through the coronary sinus to cardiac resynchronization in patients with high pacemaker dependance and lower left ventricle (LV) ejection fraction [, , ].

Epicardial lead implantation may be an alternative but requires invasive surgical placement, making it a less ideal option in patients with a prior thoracotomy. Regarding single ventricle pacing with a CS lead, low sensing and unacceptable threshold at implantation can be an important issue, especially when using a conventional RV pacing lead [, ]. Quadripolar LV leads are associated with more satisfactory results as they are able to pace in several places of the LV wall, multiple vectors along the lead, allowing us to avoid suboptimal pacing sites, such as places with fibrosis [].

A 42-year-old patient presented in the emergency room due to episodes of syncope. The patient had a past medical history of rheumatic valvular heart disease and had been submitted to three valvular surgeries. In the first one, at age of 20 years old, a mitral and tricuspid valvuloplasty were performed, and in the second one, at the age of 26 years old, due to progressive valvular stenosis, a mechanical mitral valve and a biological tricuspid valve were implanted. As a consequence of the second surgery, in the post-operative period, a high degree atrioventricular block occurred, and a right infraclavicular dual-chamber pacemaker (PM) was implanted. Owing to the presence of the prosthetic tricuspid valve, the ventricular pacing lead (unipolar) was placed through the CS in the anterior vein. In the meanwhile, the patient developed permanent atrial fibrillation (AF) and had the PM reprogrammed to VVI mode.

A week before the current hospital admission, the patient had the third valvular surgery. At this time, he had replaced the tricuspid valve for a mechanical valve and was submitted to an aortic mechanical valve implantation. The immediate post-operative period was uncomplicated. No performance data of the pacemaker were analyzed by this time.

One week after discharge he had 3 episodes of syncope and went to the emergency department. The admission electrocardiogram (ECG) revealed AF and pacing spikes without ventricular capture and prolonged ventricular asystole (Fig. 1).

The device interrogation showed that the threshold was >5 V/0.5 ms, and the device was programmed with an output of 7.5 V/ 0.5 ms to assure ventricular capture. The clinical case was discussed in a heart team meeting, where due to the history of three previous heart surgeries with probable multiple and severe adhesions and fibrosis of mediastinum complicating the placement of an epicardial lead, it was decided to try an endocardial approach. Through a left subclavian access, the CS was canulated with an Extended Hook sheath (Medtronic®, Attain Command, Minneapolis, MN, USA) and a lateral tributary vein with a sub-selective sheath (Medtronic®, Attain Select 90s). A quadripolar lead (Medtronic®) was placed in the lateral vein of the CS (Fig. 2).

A cardiac resynchronization therapy pacemaker (CRT-P) device (Biotronik® Enitra Hf-T Qp, Berlin, Germany) was connected to the LV quadripolar lead and a plug was placed at the RV port. In this circumstance the device was programmed in VVI-BiV at 55 bpm. As the device did not have RV sensing and was programmed in LV only pacing, we used the Biotronik® LV T-wave protection algorithm as a sensing mechanism. The old device connected to the malfunctioning lead was switched-off and “abandoned” without system extraction.

Post-procedural ECG (Fig. 3) showed AF rhythm with some periods of the patient's rhythm alternating with ventricular pacing. Notice that there is ventricular sensing, avoiding pacing in the repolarization period, but it does not reset the timer to 1090 ms (VVI 55 bpm). Post-procedural X-ray showed no complications, and the patient was discharged. At 1 year of follow-up, the patient was clinically well, asymptomatic, and without events or hospital admissions. The device interrogation at 1 month showed 50 % LV pacing, with sensing 7.9 mV, impedance of 273 Ohms, and pacing threshold of 3.2 V/ 0.4 ms. The device interrogation at 6 months showed 62 % LV pacing, with sensing 9.6 mV, impedance of 351 Ohms, and pacing threshold of 3.2 V/1.25 ms.

The patient's transthoracic echocardiogram revealed functioning mechanical valves in the aortic, mitral, and tricuspid positions, with adequate gradients to the respective prosthesis, no evidence of perivalvular leaks, non-dilated and non-hypertrophic LV (interventricular septum and posterior wall 10 mm) with good left ventricular function (Simpsons method ejection fraction of 56 %), mild decrease of RV function (tricuspid annular plane systolic excursion 15 mm), bi-atrial enlargement (LA indexed volume 53 ml/m²), and no signs of pericardial effusion.

The use of a single ventricular lead placed in the CS in patients with prosthetic tricuspid valves is well established [, , , , ]. Data show that ventricular sensing by an LV lead placed in the coronary veins is feasible and reliable []. When compared to the unipolar leads, quadripolar leads have the advantage of having more pacing sites which can optimize the pacing threshold [], but the disadvantage of not allowing to perform conventional ventricular sensing, as it is usually achieved by the RV lead in patients with CRT-P. Among device manufacturers, Biotronik® resynchronization devices have independently RV and LV pacing and sensing. While RV sensing is used for RV-based timing and RV pacing inhibition, LV sensing is only used to prevent a pacemaker-induced arrhythmia, as it inhibits a scheduled pace event for 300 to 500 ms to avoid LV pacing during the vulnerable recovery period (T wave) but does not reset the lower rate timer – this feature is referred to as LV T-wave protection []. Here, we describe a patient with a mechanical tricuspid valve and a previous malfunctioning CS unipolar lead that was submitted to a second lead implantation in the CS. It was decided to use a quadripolar lead due to the several pacing options allowing the optimization of the pacing threshold. Due to the presence of patient's heart rhythm for periods, a Biotronik® CRT-P generator was chosen to perform LV sensing using the LV T-wave protection algorithm. The chosen endocardial approach avoided a fourth surgical intervention to place an epicardial lead, that would have been associated with increased morbidity. As far as we know, it is the first described case of a patient with prosthetic tricuspid valve and a previous CS malfunctioning lead that was submitted to a single ventricular quadripolar lead placement in the CS, programmed at VVI-BiV and using only the LV T-wave protection algorithm as sensing mechanism.

Written informed consent was obtained from the patient for the publication of this case report.

PSC and Mario Martins Oliveira: designed and directed the project. André and PSC collected the data. AG and BLT wrote the manuscript with support from PSC and MMO.

No acknowledgments to report.