Left Pericardiophrenic Vein Pacing for Tachy-Brady Syndrome Due to an Obstructing Cardiac Angiosarcoma

We describe a case of a permanent pacemaker lead placement via the left pericardiophrenic vein for the treatment of tachy-brady syndrome due to a primary cardiac angiosarcoma. (Level of Difficulty: Advanced.)

A Meta-Analysis Of Quadripolar Versus Bipolar Left Ventricular Leads On Post-Procedural Outcomes

Objective: We aimed to perform a meta-analysis from eligible studies to analyze the true impact of QL when compared with BL with regard to post-procedural outcomes including lead deactivation, revision or replacement. Background: Many observational and retrospective studies showed that quadripolar left ventricular leads (QL) are associated with better outcomes and fewer complications when compared with bipolar leads (BL). Methods: We performed a comprehensive literature search through June 30, 2015 using: quadripolar, bipolar, left ventricular lead and CRT in Pubmed, Ebsco and google scholar databases. Results: The analysis included 8 studies comparing QL and BL implantation. Post-procedural outcomes such as lead deactivation, revision or replacement were used as primary outcome and assessed with Mantel-Haenszel risk ratio (RR). Secondary outcomes included total fluoroscopy/procedure time, occurrence of phrenic nerve stimulation (PNS) and all-cause mortality on follow up. Follow-up duration for the studies ranged from 3 to 60 months. Compared with BL, the use of QL is associated with 52 % reduction (relative risk 0.48; 95% CI: 0.36-0.64, p=0.00001) in the risk of deactivation, revision or replacement of the LV lead. QL had significantly lower fluoroscopy/procedure time, PNS and all-cause mortality when compared with BL. Conclusion:Our meta-analysis shows that QL implantation was associated with decreased risk of LV lead deactivation, revision or replacement when compared with BL.

A Case of Useful Short-Spaced Bipolar Pacing of a Left Ventricular Lead to Avoid Phrenic Nerve Stimulation

A 48-year-old woman underwent cardiac resynchronization therapy defibrillator implantation. Coronary sinus (CS) venography showed only one adequate anterior branch for a left ventricular lead. We were able to introduce a quadripolar left ventricular lead (Medtronic 4398-88 cm) to the distal portion of the anterior branch. Although phrenic nerve stimulation (PNS) occurred due to distal bipolar pacing (distal 1-mid 2, with 21-mm distance) and proximal pacing (mid 3-proximal 4, distance 21mm), short-spaced bipolar pacing (mid 2-3, distance 1.3 mm) did not induce PNS until 9V pacing. Shared bipolar pacing from each left ventricular electrode (distal 1 to proximal 4) as cathode and a right ventricular (RV) coil as anode resulted in PNS by 3.0V at 0.4 ms. Although quadripolar pacing could avoid PNS by switching the pacing site (ie, from distal bipolar to proximal bipolar), it might not avoid PNS in cases where the phrenic nerve and CS branch are parallel and in close proximity. We found that even though the phrenic nerve and CS branch were parallel and close, short-spaced bipolar pacing could avoid PNS. In conclusion, short-spaced bipolar pacing selected by quadripolar pacing might be beneficial to avoid PNS when the implantable branch is limited.

Successful transjugular extraction of a lead in front of the anterior scalene muscle by using snare technique

The incidence of cardiovascular implantable electronic device infection is increasing. We report a case of and successful device removal in a 79-year-old man with implantable cardioverter-defibrillator infection. Right phrenic nerve paralysis was evident on chest radiography. The lead was in front of the anterior scalene muscle, close to the left phrenic nerve. Therefore, extraction carried a risk of bilateral phrenic nerve paralysis. The lead was successfully extracted from the right internal jugular vein by using the snare technique. No complications occurred, and the extraction was successful.

Comparison of different pacing strategies to minimize phrenic nerve stimulation in cardiac resynchronization therapy

INTRODUCTION

Phrenic nerve (PN) stimulation (PNS) frequently limits cardiac resynchronization therapy (CRT). Yet, pacing strategies to minimize PNS have not been systematically compared. We propose to: (1) compare different pacing strategies to minimize PNS in CRT and (2) evaluate differences between PN and left ventricular (LV) capture thresholds among LV pacing configurations.

METHODS AND RESULTS

PN and LV thresholds were obtained using 6 LV configurations in 28 patients with any PNS during CRT implantation or replacement. Incidence of PNS was compared in all LV configurations by programming pacing output to (1) One Volt (V) above LV threshold, (2) triple pulse width (PW) at LV threshold, and (3) 1.5 times LV threshold for each patient. PN thresholds and PN strength-duration curves were statistically different between configurations (P < 0.05). Ring→RVcoil and Ring→Can had the largest difference between PN and LV thresholds. Pacing output programmed to 1.5 times LV threshold, 1 V above LV threshold, and triple PW at LV threshold had similar probability of PNS between LV configurations. However, 1 V above LV threshold and triple PW at LV threshold frequently resulted in poor (< 30%) LV capture safety margin (14-43% and 53-68%, respectively). Freedom from PNS (programmed output at twice LV threshold) was found in 88%, 84%, and 52% with 6, 3, or 2 available LV configurations, respectively.

CONCLUSION

Multiple LV pacing configurations marginally increase the probability of avoiding PNS by electronic reprogramming. Pacing output programmed to 1.5 times LV threshold is an additional alternative to minimize PNS when electronic reprogramming options are limited.

Occurrence of phrenic nerve stimulation in cardiac resynchronization therapy patients: the role of left ventricular lead type and placement site

AIMS

Unwanted phrenic nerve stimulation (PNS) has been reported in ∼1 in 4 patients undergoing left ventricular (LV) pacing. The occurrence of PNS over mid-term follow-up and the significance of PNS are less certain.

METHODS AND RESULTS

Data from 1307 patients enrolled in pre-market studies of LV leads manufactured by Medtronic (models 4193 and 4195 unipolar, 4194, 4196, 4296, and 4396 bipolar) were pooled. Left ventricular lead location was recorded at implant using a common classification scheme. Phrenic nerve stimulation symptoms were either spontaneously reported or identified at scheduled follow-up visits. A PNS-related complication was defined as PNS resulting in invasive intervention or the termination of LV pacing. Average follow-up was 14.9 months (range 0.0-46.6). Phrenic nerve stimulation symptoms occurred in 169 patients (12.9%). Phrenic nerve stimulation-related complications occurred in 21 of 1307 patients (1.6%); 16 of 738 (2.2%) in the unipolar lead studies, and 5 of 569 (0.9%) in the bipolar lead studies (P = 0.08). Phrenic nerve stimulation was more frequent at middle-lateral/posterior, and apical LV sites (139/1010) vs. basal-posterior/lateral/anterior, and middle-anterior sites (20/297; P= 0.01). As compared with an anterior LV lead position, a lateral LV pacing site was associated with over a four-fold higher risk of PNS (P= 0.005) and an apical LV pacing site was associated with over six-fold higher risk of PNS (P= 0.001).

CONCLUSION

Phrenic nerve stimulation occurred in 13% of patients undergoing LV lead placement and was more common at mid-lateral/posterior, and LV apical sites. Most cases (123/139; 88%) of PNS were mitigated via electrical reprogramming, without the need for invasive intervention.

Effect of bipolar electrode spacing on phrenic nerve stimulation and left ventricular pacing thresholds: an acute canine study

BACKGROUND

Phrenic nerve stimulation (PNS) is a common complication of cardiac resynchronization therapy when left ventricular (LV) pacing occurs via a coronary vein. The purpose of this study was to evaluate the effects of bipolar electrode spacing on PNS and LV pacing thresholds.

METHODS AND RESULTS

Electrophysiology catheters with standard (2 mm-5 mm-2 mm) or modified (1 mm-5 mm-1 mm) interelectrode spacing was, respectively, inserted in a posterior/lateral cardiac vein in a randomized order in 6 anesthetized dogs via jugular access. The phrenic nerve was dissected via a left minithoracotomy and repositioned over the vein as close as possible to one of the electrodes. The presence of PNS was verified (ie, PNS threshold <2 V at 0.5 ms in unipolar configuration). Bipolar pacing was delivered using the electrode closest to the phrenic nerve as the cathode, and multiple bipolar electrode spacing configurations were tested. During bipolar pacing, PNS threshold increased as bipolar electrode spacing was reduced (P<0.05), whereas LV pacing thresholds did not change significantly (P>0.05). Compared with a standard bipolar electrode spacing of 20 mm for LV leads, 1 and 2 mm bipolar electrode spacing resulted in a PNS threshold increase of 5.5±2.2 V (P=0.003) and 2.8±1.7 V (P<0.001), respectively. Similarly, PNS threshold increased by 6.5±3.7 V with 1 mm and by 3.8±1.9 V with 2 mm bipolar pacing (both P<0.001), compared with unipolar pacing.

CONCLUSIONS

This study suggests that reducing LV bipolar electrode spacing from the standard 20 mm to 1 or 2 mm may significantly increase the PNS threshold without compromising LV pacing thresholds.

Inadvertent identification of the left pericardiophrenic vein following laser lead extraction to guide left ventricular lead placement

Phrenic nerve stimulation (PNS) is a frequent occurrence in patients implanted with a cardiac resynchronization therapy device. We present a case where identification of the left pericardiophrenic vein, which runs alongside the phrenic nerve, was used to guide left ventricular lead placement in order to minimize the risk of PNS.