CASE REPORT

Low Defibrillation Threshold in a Patient with aDual-Coil Defibrillator Lead Implanted through aPersistent Left Superior Vena CavaTHOMAS A. WILLIAMS, Jr., M.D., OLUWOLE ABE, M.D., CRISTINA A. MITRE, M.D.,and JOHN KASSOTIS, M.D.From the Department of Electrophysiology, SUNY Downstate Medical Center, Brooklyn, New York

Several reports have described the successful insertion of implantable cardioverter defibrillator (ICD) inpatients with a persistent left superior vena cava (PLSVC). The implanters have used various techniquesto achieve appropriate lead placement. In our case, the use of a long sheath, guided by a deflectablecatheter, not only facilitated proper implantation of the lead, but also provided a unique position of thedual-coil lead. This resulted in a very low defibrillation threshold (DFT). We describe a case of a patientfound to have a PLSVC at implant who after successful insertion of the ICD exhibited DFT ≤5 J. (PACE2012;00:e1–e2)

implantable cardioverter defibrillator, persistent left superior vena cava, defibrillation threshold

Case ReportThis is a case of a 49-year-old man with

a nonischemic dilated cardiomyopathy and leftventricular ejection fraction (LVEF) of 20%, onoptimal heart failure medication, who was admit-ted for the evaluation of syncope. The patient wasfound to have frequent episodes of monomorphic,nonsustained ventricular tachycardia, with leftbundle branch block morphology. After successfulelectrophysiology study and ablation of theventricular ectopy, originating from right ventricleoutflow tract, the patient had a repeat 2-D-echoafter a few months, with no improvement in theLVEF.

The patient was referred for implantablecardioverter defibrillator (ICD) implantation. Theleft brachiocephalic venous system was accessedvia a cephalic vein cut-down technique. Underfluoroscopic guidance, the dual-coil defibrillatorlead appeared to take a sharp inferiorly directedcourse staying to the left of the spine, crossingmidline via the coronary sinus (CS) into the lowright atrium (RA). This was consistent with anexit from the ostium of the CS, via a persistent

Financial disclosure: Consultant/speaker for Medtronic, St.Jude Medical, and Boston Scientific.

Address for reprints: John Kassotis, M.D., Eng.Sci.D.,F.A.C.P., F.A.C.C., F.A.S.A., Director, Clinical CardiacElectrophysiology, SUNY Downstate Medical Center,440 Clarkson Avenue, Box 1199, Brooklyn, NY 11203.Fax: 718-270-4106; e-mail: JTK747@AOL.COM

Received July 16, 2011; revised December 13, 2011; acceptedJanuary 9, 2012.

doi: 10.1111/j.1540-8159.2012.03432.x

left superior vena cava (PLSVC), confirmed byvenography.

The 65-cm dual-coil defibrillator lead (Riata,model #1580, St. Jude Medical, Inc., St. Paul,MN, USA) was placed in the RA and allowedto loop around the lateral wall before crossingthe tricuspid valve. After several failed attemptsto properly place the lead using various shapedstylets, a long 9-Fr braided Medtronic Attain (50cm) catheter sheath (Medtronic Inc., Minneapolis,MN, USA) was placed into the RA. A 7-Frdeflectable Mariner ablation catheter (MedtronicInc.) was placed through the sheath, and wewere able to successfully deflect and pass thesheath across the tricuspid valve into the cavityof the right ventricle (RV). The lead was thenadvanced through the sheath and actively fixedto the anterior septal wall (Fig. 1). The measuredR wave was ≥12 mV, impedance 600 Ohms, andthreshold 0.8 V @ 0.5 ms. The distal coil sat inthe proximity of the RV anterior septum, whereasthe proximal coil lay within the CS (posterior baseof the left ventricle). This position successfully“triangulated” the myocardium between the twocoils and the generator (“active can”), as seen inthe lateral projection (Fig. 1). A St. Jude MedicalAtlas generator, model # V-193, was connected tothe lead.

Ventricular fibrillation (VF) was induced by asynchronized 2-J T-wave shock after a pacing cyclelength at 400 ms and coupling interval of 300 ms.The device properly sensed VF and restored sinusrhythm with a synchronized 15-J shock; there wereno missed sensed beats at a sensitivity of 1.0 mV.VF was initiated a second time and during thisinduction sinus rhythm was successfully restoredwith a 5-J shock.

C©2012, The Authors. Journal compilation C©2012 Wiley Periodicals, Inc.

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Figure 1. Final position of the dual-coil defibrillation lead.

Discussion

The prevalence of a PLSVC has been estimatedat 0.3–0.5% in an otherwise structurally normalheart and as high as 11% in congenitallyabnormal hearts, representing the most commonthoracic venous abnormality.1 Several case reportshave described successful pacemaker, ICD, andbiventricular ICD implants through these anoma-lies.1–3 Different pre-shaped stylets and singleor dual-coil leads have been used to success-fully navigate across a PLSVC for optimal RVdefibrillator lead placement. Right-sided implantsare potentially more technically challenging,especially in the presence of a right superiorvena cava atresia, observed in 10% of patientswith a PLSVC.2 In this case, a long braidedvascular sheath delivered by a deflectable catheterfacilitated proper lead positioning.

The most important aspect of placing adefibrillator lead is to achieve an anatomic situ-ation that maximizes the amount of myocardiumavailable for defibrillation, thus minimizing therisk of device failure. In patients with a PLSVC,single-coil defibrillator leads have been used inan attempt to avoid a potential juxtaposition of

the two coils due to this anatomic anomaly. Inour case, the proximal coil traversed the leftventricle epicardially, lying in a posterior-basallocation, whereas the distal coil sat on the anteriorRV septum (Fig. 1). This particular lead positionmaximized the amount of myocardium availablefor defibrillation. There is a well-describedprobabilistic nature of the dose-response curvefor defibrillation, which varies according to themyocardial mass, the conductive properties of themyocardial cells, and changes in both cellular andtissue electrophysiologic properties.4,5 However,in this case the most important modifiable factor,in an attempt to optimize defibrillation threshold(DFT), was the myocardium encompassed by theICD system.

This case report highlights a few importantissues. First, a dual-coil defibrillation lead can besuccessfully navigated and properly placed in thepresence of a PLSVC; second, “triangulating” themyocardium between the two coils and the “activecan” maximized the myocardial mass availablefor defibrillation and led to a very low DFT.Investigators have shown improved DFTs with adedicated CS lead,6 whereas our case illustratesthis in a patient with a PLSVC.

References1. Biffi M, Boriani G, Frabetti L, Bronzetti G, Branzi A. Left

superior vena cava persistence in patients undergoing pacemaker orcardioverter-defibrillator implantation: A 10-year experience. Chest2001; 120:139–144.

2. Favale S, Bardy GH, Pitzalis MV, Dicandia CD, Traversa M, RizzonP. Transvenous defibrillator implantation in patients with persistentleft superior vena cava and right superior vena cava atresia. Eur HeartJ 1995; 16:704–707.

3. Kapetanopoulos A, Peckham G, Kiernan F, Clyne C, Kluger J, MigeedMA. Implantation of a biventricular pacing and defibrillator devicevia a persistent left superior vena cava. J Cardiovasc Med 2006;7:430–433.

4. Ellenbogen KA, Kay GN, Lau CP, Wilkoff BL. Clinical Cardiac Pacing,Defibrillation, and Resynchronization Therapy. Philadelphia, PA,Saunders, 2007, pp. 535–555.

5. Rates MF, Jones DL, Sharma AD, Klein GJ. Defibrillationthreshold: A simple and quantitative estimate of the abil-ity to defibrillate. Pacing Clin Electrophysiol 1987; 10:70–77.

6. Faheem O, Padala A, Kluger J, Zweibel S, Clyne CA. Coronarysinus shocking lead as salvage in patients with advanced CHFand high defibrillation thresholds. Pacing Clin Electrophysiol 2010;33:967–972.

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