Biventricular ICD Implantation in a Patient with a Huge Coronary Sinus: Use of a New Active Fixation LV Lead

In this article, author Dr. Sorrentino presents a case using the Attain StarFix® Model 4195 lead, the first active fixation LV lead available in the United States. Clinical Scenario The patient is a 53-year-old male with a known nonischemic cardio-myopathy and a 20% ejection fraction (EF) for at least 18 months. He has had several recent congestive heart failure (CHF) decompensations despite medical compliance with a beta blocker, angiotensin converter enzyme (ACE) inhibitor, spironolactone and furosemide. He was admitted with a CHF decompensation, which responded to IV furosemide and temporarily suspended his beta blocker. An ECG revealed sinus rhythm with a nonspecific interventricular conduction delay of 140 msec. As the patient had baseline NYHA Class III CHF symptoms, he was felt to be a good candidate for a biventricular implantable cardioverter-defibrillator (ICD). An echocardiogram was performed revealing that his EF was 15-20% with mild mitral and tricuspid regurgitations. He was incidentally found to have a very large coronary sinus (CS) that was 2 cm in diameter at the right atrial junction. A persistent left superior vena cava (SVC), which drained into the CS and the right atrium, was confirmed by microcavitation study. The patient underwent bilateral upper extremity venography in order to plan his biventricular ICD implant procedure. The venograms (Figures 1a and 1b) revealed the persistent left and right superior vena cavae. There was no left brachiocephalic vein. The right SVC drained normally into the right atrium. Left Superior Vena Cava A persistent left SVC is an embryonic remnant of left anterior cardinal vein. Its incidence is reported to be 0.3–0.5% of the general population1 and is usually asymptomatic. The cardinal vein involutes and becomes the vein of Marshall or the ligament of Marshall. Most common amongst those with this anomaly is the presence of dual cavae in 82%, and in 60% of these, a left brachiocephalic vein connects the two cavae.2,3 The left SVC directly drains into the right atrium via the CS in 92% of cases. In the remaining cases it may drain into the left atrium directly, via an unroofed coronary sinus or into a pulmonary vein causing left to right shunting.3 Although pacemaker, ICD and even biventricular ICD implantations have been documented using the anomalous caval anatomy,4-6 we decided to implant the biventricular ICD via the right axillary vein and right vena cava. The right vena caval approach gave us the ability to use the left ventricle (LV) lead delivery tools in the manner that they were intended, that is, entering the os of the CS from the right atrium. Our biggest concern was how to keep an LV lead in a selected branch vessel without dislodgement due to the high flow, very large-sized CS. We planned to utilize a recently FDA-approved active fixation LV lead, Medtronic’s StarFix® Model 4195. LV Lead Background Information Implanters have all experienced macro or micro dislodgements of transvenous LV leads. Dislodgement can occur in up to 5-10% of all transvenous LV lead implants.7,8 LV lead dislodgement can manifest as a lack of capture, high capture thresholds, phrenic nerve or diaphragmatic stimulation, to mention a few, and ultimately lead to loss of biventricular pacing function and a lack of clinical improvement or a potential worsening of CHF symptoms. LV lead dislodgement can be disheartening to doctors and patients because adequate LV lead positioning is generally the most challenging and time-consuming part of any cardiac resynchronization therapy (CRT) or CRT defibrillator (CRT-D) implant. Further complicating LV lead dislodgement is the need to reposition and sometimes remove and replace the lead entirely. Reoperation has its own accompanying risks of: infection (by having to open a not yet completely healed pocket), venous thrombosis, bleeding, cardiac perforation, arrhythmia, and even the risk of lead repeated lead dislodgement. Some patients with LV lead dislodgement may even need referral for epicardial LV lead placement via thoracotomy. Epicardial LV lead placement by thoracotomy has its own associated morbidity/mortality in this NYHA Class III/IV heart failure population. Manufacturers have designed LV leads with various passive fixation mechanisms to reduce dislodgements, including an assortment of curves, helixes or spirals, and small tines, while trying to design leads that will be capable of negotiating the coronary venous anatomy. The coronary veins tend to be very variable in location, tortuosity, and vessel luminal diameters. An implanter faces an additional challenge of finding viable myocardium immediately adjacent to the selected branch vein and hopes not to stimulate the phrenic nerve or diaphragm directly. Many of us perform coronary venograms to create a hierarchy of potential target coronary vein tributaries and to help select the most suitable delivery tools, LV lead and fixation mechanism for that individual’s anatomy. A New Active Fixation LV Lead For this case we chose the Attain StarFix® Model 4195 lead (Medtronic, Inc., Minneapolis, MN) with deployable lobes. Approved for implantation by the FDA in June 2008, the StarFix is a 5 French, steroid-eluting, uni-polar, polyurethane-insulated lead with an IS-1 connector that can be implanted using a guidewire or stylet. The StarFix has three rows of rounded, flexible lobes that when deployed conform to the vessel lumen (Figure 2). The StarFix lead tip also has a curve near the tip to provide added contact pressure. Platinum indicator rings attached on both sides of each set of lobes make them radiopaque. When the lobes are deployed, the spaces between the indicator rings decrease, as the lobes are undeployed, the spaces increase. If pacing parameters are unacceptable the lobes can be retracted, the lead repositioned and the lobes again extended until an adequate pacing site is found. During the Case Study We obtained venous access to the right axillary vein in a standard fashion. The right ventricular (RV) pacing/shocking lead was placed in a RV apical location. The large CS ostium was cannulated with an Attain Select 90 degree inner catheter (Medtronic, Inc.) through an Attain Extended Hook CS delivery sheath (Medtronic, Inc.) over a guidewire. The CS diameter was too large for a standard balloon-tipped catheter to perform occlusive retrograde coronary venograms (Figure 3). Therefore, we probed the CS with the Attain Select and performed hand injections along its course looking for tributaries. Finding a posterior coronary vein, a venogram highlighted this vessel and also opacified most of the other coronary veins via collaterals (Figure 4). We selected this posterior-lateral branch and advanced the StarFix® lead over a 0.14 guidewire. Once the StarFix was in a suitable location, the lobes were deployed (Figures 5a and b). The extended bipolar acute pacing threshold was 1.0 volts at 0.5 msec, 1.1 mA current, 1053 ohm impedance, and R waves measured 12.4 mV. There was neither diaphragmatic muscle nor phrenic nerve stimulation. An active fixation atrial lead was placed in the right atrial appendage. Each lead’s pacing and sensing parameters were excellent. We were now prepared to remove the coronary sinus sheath. The active fixation mechanism makes one feel very confident in the lead’s stability while removing the delivery sheath. We reassessed the LV lead pacing parameters after sheath removal and they were unchanged. I secured the biventricular pulse generator to the leads and placed the CRT-D system into the subcutaneous pocket. Defibrillation thresholds were ≤ 20 joules at 46 ohms. On the following day, the patient was discharged home. (Figures 6a and b) Discussion How many times have you had an LV lead displace or completely dislodge during the removal of the delivery sheath? When you repeat the pacing parameters immediately after CS sheath removal, how often have you seen the LV pacing threshold worsen, but still be acceptable? Did the threshold increase represent a micro or macro dislodgement? Did the fluoroscopic image of the LV lead change? Most CRT studies do not record these data or consider these changes as potential lead displacements in their published statistics. The frustration caused by lead dislodgement so close to the end of the procedure is worsened when the lead placement was particularly difficult and time consuming. The active fixation mechanism of the StarFix has made me a more confident LV lead implanter. Compared to other available LV leads, one no longer has to wedge passive fixation leads into a distal vein branch in the hopes of stability. LV lead implanters will find that this lead gives them more opportunities for successful implantations because you may be able to select larger diameter vessels even in more proximal or mid-branch coronary vein locations with little concern for dislodgement. As with any new lead, there will be a short period of learning how and where to use this lead. Implanters may question as to whether the StarFix lead should only be used in cases with difficult anatomy, as this case, or in patients with a prior history of LV lead dislodgement. You will find that it replaces some of the older variety LV leads due to its versatility in addition to StarFix’s acute and long-term stability. It is reasonable to consider the StarFix lead as a first-line LV lead. The Attain StarFix 4195 LV Lead Clinical Trial final data is with the study’s publication committee, and manuscript submission is soon anticipated. Editor’s Note: The author discloses that he is actively on two AEACs and consults for Medtronic Inc. He was also on the 4195 Clinical Study AEAC.