Quadripolar Left Ventricular Lead in a Patient with CRT-D Does Not Overcome Phrenic Nerve Stimulation.

Effective cardiac resynchronization therapy (CRT) requires an accurate atrio-biventricular pacing system. The innovative Quartet lead is a quadripolar, over-the-wire left ventricular lead with four electrodes and has recently been designed to provide more options and greater control in pacing vector selection. A lead with multiple pacing electrodes is a potential alternative to physical adjustment of the lead and may help to overcome high thresholds and phrenic nerve stimulation (PNS).

Case Report

A 47-year-old patient with history of worsening non-ischemic dilated cardiomyopathy was admitted to our hospital for the evaluation for primary prevention of sudden cardiac death (SCD). The patient has Brady-Tachy syndrome (BTS) by permanent atrial fibrillation since 2005, severe LV dysfunction with LVEF 17%, but no ventricular dyssynchrony and QRS duration 100 ms. The patient was symptomatic (NYHA functional Class III) despite optimal recommended medical therapy.1 To address a class I indication for permanent ventricular pacing2 in this patient we elected to perform biventricular stimulation (cardiac resynchronization therapy; CRT) with defibrillator (CRT-D) to prevent cardiac desynchronization.3

CRT with defibrillator (CRT-D) implantation was performed by transvenous approach. We chose a new quadripolar transvenous lead (Quartet lead, Multipolar Quartet™ 1458Q, St. Jude Medical), because of its capabilities to manage a high pacing threshold and PNS instead of needing to reposition the lead.4,5

The venogram of the coronary sinus (CS) indicated an anterior lateral vein and a good lateral and posterior vein (Fig. 1). The lateral vein was selected as the target and the quadripolar LV lead was placed there. All pacing configurations and pulse durations were tested with PNS present in 10/10 options. The other target vein for the quadripolar LV lead was the posterior vein with origin in the proximal portion of the CS. This position of the lead shown also PNS present in 10/10 options. The quadripolar LV lead was relocated in to the last target anterior lateral vein (Fig. 2). PNS was observed and ten different LV pacing configurations were tested. PNS did not occur during pacing from only one of the four electrodes and the LV pacing configuration was programmed accordingly: distal 1-mid 2. During the pre-discharge follow-up the patient presented with PNS. All pacing configurations and pulse duration were tested with PNS present in 10/10 options. PNS was not affected by body position and was also observed in the supine and left lateral positions. The follow-up visits at 3- and 6-months showed PNS and an increased threshold without significant change in other measurements.

Figure 1

A coronary sinus venogram indicated an anterior lateral vein and a good lateral vein.

Figure 2

Final position of quadripolar left ventricular lead in anterior-lateral vein.

Discussion

Although cardiac resynchronization therapy (CRT) has been demonstrated to be an effective treatment for heart failure patients, up to 30% to 40% of the patients do not show a favourable response.6 Location of the left ventricular (LV) pacing lead is one of the determinants of success. The implantation procedure includes several challenging technical issues and strongly depends on the highly variable anatomy of the coronary sinus and tributaries.6 The optimal position of the LV pacing lead is the site of latest activation in the left ventricle, which enables effective resynchronization. Furthermore, PNS occurs in 37% of CRT patients at implant or follow-up. PNS can affect, and in some cases limit, the long-term success of CRT.7 To address this common problem, the manufacturers of CRT devices offer a range of configurations aimed at preventing PNS. A quadripolar LV lead has recently been designed which provides more programming configurations and may help to overcome high thresholds and PNS.4,5 There are several publications concerning qaudripolar electrode implantation which show elimination of PNS, but the optimal LV pacing configuration should be determined on the basis of individual patient testing.4,5,8 Here we have reported a case in which the use of the quadripolar left ventricular lead pacing depended on the highly variable anatomy of the coronary sinus and resulted in the occurrence of stable PNS at 3- and 6-months. In this case, even 10/10 configurations could not prevent occurrence of PNS. To our knowledge, this is the first case which demonstrated this uncommon event.