Utilizing a GPS-Based Imaging System for Reduced Fluoro and Successful Implantation of a CRT-D Device in a Previously Failed CRT Implant

Background

Cardiac resynchronization therapy (CRT) device implants have historically been one of the more complex procedures in the electrophysiology lab. Factors such as limitations in available tools, clinical/technical expertise, and anatomical abnormalities are a few of the major contributors to obstacles in successful placement of the left ventricular (LV or coronary sinus) lead. The commonality of each factor, independently and collectively, is that they all contribute to the increased dependence on fluoroscopy for accurate placement. In CRT device implantation, there is a direct correlation between procedure time and the amount of fluoroscopy necessary to perform a successful case. The positioning of the LV lead (via the coronary sinus) contributes to the majority of the overall radiation exposure in CRT device implants. Due to the complexity of these implants, LV lead implant failures occur in approximately 6-12% of CRT device implants, despite continuous improvements in LV lead implantation techniques and tools.¹ The radiation burden to patients, physicians, and staff due to procedure complexity can oftentimes overwhelm EP programs, as there can be a constant struggle to both balance procedure success and achieve reasonable levels of radiation dose. 

Excessive radiation exposure (i.e., >60 minutes and/or >3 Grays in most institutions) is a major factor in validating the decision to abort CRT device implant cases. Comparatively, one minute of fluoroscopy is correlative to the dose equivalence of approximately 50 consecutive chest x-rays. A study conducted by Perisinakis et al suggested that mean fluoroscopy times for new implant CRT devices are approximately 35.2 minutes (>1,700 CXRs).² Today, improved technology, techniques, and tools have significantly improved, and new CRT device implants can typically range from 5-20 minutes of fluoroscopy (≈1,000 CXRs), with all procedural variables considered. Radiation exposure is unique in that it is directly relative to product limitations, technical challenges, anatomic variability, etc. These procedure variables, singularly or collectively, can directly influence the amount of radiation required to perform a procedure and are considered predictors of case success. 

In the ideal world, if CRT device tools, technologies, and techniques would further evolve to achieve a reasonable degree of procedural independence from fluoroscopy in both routine and complex cases, then radiation exposure would be minimized. GPS-based systems such as MediGuide^™ Technology (St. Jude Medical) provide such a concept. Once an initial CS venogram is achieved, MediGuide Technology enables EPs to effectively position MediGuide-enabled tools without utilizing fluoroscopy, thus mitigating radiation threshold time in relation to procedure complexity. Within the functionality of a GPS-based system such as MediGuide, practitioners are provided more time for the technical manipulation of the LV lead and corresponding tools, because fluoroscopy is utilized as a secondary imaging feature, subordinate to the GPS software. As a result, complex procedures that require extensive procedure times have yielded substantially lower radiation doses than traditional CRT device implant techniques. 

At John C. Lincoln Medical Center, we have implemented a technique using MediGuide Technology as the primary imaging tool, thereby minimizing fluoroscopy in routine and complex cases (Figures 1 and 2). In this case study, we present a complex CRT device implant that was previously aborted by another site, presumably by both technical/anatomic complications and excessive radiation exposure. This patient had multiple comorbidities and presented a very difficult case scenario. This procedure was specifically selected due to its complexity as well as to demonstrate the successful implant of a CRT-D device (Quadra Assura, St. Jude Medical) and LV lead (Quartet quadripolar lead, St. Jude Medical) using the innovative GPS-based MediGuide technique to overcome typical procedural challenges and variables, while also significantly reducing procedural fluoroscopy.

Case Description 

A 60-year-old female presented to the EP lab with a CRT-D device at end of life. The patient has a history of New York Heart Association (NYHA) class III chronic systolic congestive heart failure (CHF), non-ischemic cardiomyopathy with an ejection fraction less than 20%, left bundle branch block with QRS duration of 184 milliseconds, hypertension, ventricular tachycardia, and elevated B-type natriuretic peptide. The patient had a Medtronic CRT-D device implanted four years prior, but without an LV lead (LV lead port was plugged) due to unsuccessful implant. The patient reported increased fatigue, orthopnea, and dyspnea on exertion with decreased walking distance, as well as loss of appetite. 

Dr. Mark Seifert consented the patient for the procedure to include a CRT-D explant and generator replacement, and implant of a new LV lead under conscious sedation. The patient was placed on the procedural table and connected to hemodynamic monitoring (Mac-Lab Recording System, GE Healthcare), external defibrillator pads (LIFEPAK 20e, Physio-Control), and a MediGuide Patient Reference Sensor (St. Jude Medical). A pre-procedure antibiotic was administered. The patient was then prepped and draped in sterile fashion and sedated with midazolam, fentanyl, and diphenhydramine via intravenous route. 

One percent lidocaine was used to infiltrate the tissue in the left prepectoral region. An incision was made, the pocket was accessed, and the existing CRT-D device was removed. The axillary vein was cannulated with a thin-walled needle using 0.5 min of fluoroscopy (Artis zee, Siemens Healthcare), and a 10 French (Fr) sheath was inserted. At this point, a left anterior oblique (LAO) fluoro image (utilizing 0.2 min) was obtained using the MediGuide software. The image intensifier (II) was then placed back in the anterior-posterior (AP) position as the MediGuide software continued to loop the image, synching it to current respiratory and cardiac motion while adjusting for patient movement. Upon initial fluoroscopic inspection, it was noted that the atrial lead was pulled back and the ventricular lead had minimal slack. A stylet was advanced into the atrial lead and the body of the lead advanced without utilizing fluoroscopy. Attempts to advance slack into the body of the ventricular lead via a stylet were unsuccessful. 

With the atrial and ventricular leads re-sutured into place, a MediGuide-enabled CS slittable sheath was then advanced over a 6 Fr MediGuide-enabled decapolar steerable catheter via the axillary access. Utilizing the MediGuide software, the superior vena cava was identified and a 3D landmark was applied over the pre-recorded LAO fluoro loop. The CS was not identified, so a second MediGuide-enabled CS slittable sheath was used. A small amount of ISOVUE-370 (Bracco Imaging) contrast was injected to get a limited view of the CS os using fluoro. With the limited MediGuide-enabled products available at this time, an angled inner catheter was inserted using a MediGuide 0.014-inch guidewire for 3D visualization. Using the pre-recorded fluoro loop, a torquer (0.014-in wire steering tool) was secured in place on the guidewire at the hub of the inner cath with the distal portion positioned just inside the catheter to mark the inner catheter location in real time. Using this technique, a glide catheter and Amplatz left 2 catheter (Merit Medical) were also tried unsuccessfully. With the constant manipulation of the decapolar catheter, deflection capability became compromised and an additional decapolar catheter was needed. 

Multiple attempts to cannulate the CS proved difficult; however, the MediGuide-enabled wide outer CS slittable sheath was finally advanced over the decapolar catheter into the CS. A CS venogram cine loop on MediGuide was performed in the right anterior oblique (RAO) and LAO views. With the II back in AP position, the Quartet quadripolar lead (St. Jude Medical) was inserted using the MediGuide-enabled 0.014-inch guidewire with the MediGuide insertion tool. Quick fluoro images were obtained to verify LV lead placement. LV lead thresholds were obtained, and the outer CS sheath was slit for removal. Unfortunately, the LV lead dislodged during the removal process, which extended the length of the procedural time. However, with the 3D visualization landmarks from the MediGuide navigational technology, successful implantation of the LV lead was achieved with a new outer CS slittable sheath and decapolar steerable catheter.

The leads were then connected to a new CRT-D device (St. Jude Medical), placed in an TYRX Antibacterial Envelope (Medtronic TYRX), and inserted into the pocket. The pocket was closed with running sutures of 0 Vicryl, 2-0 Vicryl, and 4-0 Vicryl followed by octyl cyanoacrylate glue. At implant, P waves were greater than 5 millivolts (mV) and R waves of 8.9 mV. Capture thresholds were 0.5 volts (V) in the right atrium, 1.0 V in the right ventricle, and 1.5 V in the left ventricle, all at a pulse width of 0.5 milliseconds and impedances in the three leads respectively of 430 ohms, 440 ohms, and 550 ohms. A single DC fibber induction was performed after sedation with a propofol bolus, resulting in rescue during first therapy of 25 joules with lead impedance of 39 ohms. No immediate complications were noted. The patient tolerated the procedure well with conscious sedation. Antibiotics were continued overnight, and the patient was discharged the following day.

Despite the markedly prolonged overall procedure time just above five hours, the fluoroscopic exposure time was limited to 1.5 minutes using MediGuide. Although four CS sheaths, three decapolar catheters, and two MediGuide 0.014-inch guidewires were required to implant the LV lead alone (due to an unconventional posterior takeoff of the CS with an inferiorly coursing narrow proximal portion, and multiple Thebesian and CS valves), successful implantation of the LV lead was achieved in an otherwise failed attempt at initial implant four years prior. 

Discussion

The John C. Lincoln Medical Center cardiac team, along with the support from St. Jude Medical, has continued to achieve positive milestones in reducing fluoroscopy times beyond this case study. We have continued to identify areas in which we have reduced fluoroscopy in CRT device implants, such as subclavian venous access. A technique in which we utilize a thin-walled Tuohy needle and the 0.014-inch MediGuide-enabled guidewire has shown to be effective in reducing the fluoroscopy involved in achieving venous access. This progressive practice has been a major contributor in reducing implant times to less than one minute of total fluoroscopy. On the other hand, CRT device implants can be rather taxing on lab time and product usage, and can essentially result in an unprofitable procedure (Figure 3). However, these alternatives in clinical practice improve procedural success independent of threshold fluoroscopy times to deliver a therapy in patients whose options would be otherwise limited. Dr. Seifert, an innovator in fluoro reduction strategies, supports this concept by stating, “MediGuide has allowed us to continue implant efforts unhampered by fluoroscopy times to successfully complete implants that otherwise would not have been achieved [within the confines of the EP lab].” 

Summary

CRT device implants continue to be one of the more challenging procedures in electrophysiology. The continued advancement in CRT device tools and implant techniques has made positive strides in reducing procedural fluoroscopy time, cumulative radiation dose, and increased LV lead implant success. Despite these advancements, CRT device implants range from 5-20 minutes, which yield the dose equivalence of 250-1,000 chest x-rays. This case study is an example of how a GPS-based imaging system (MediGuide) can be used with innovative tools to systematically reduce fluoroscopy times in routine and complex CRT device implants. At our institution, we have continued to refine the use of these technologies with the intent to reduce fluoroscopy times in CRT device implants in a manner that is applicable and consistent for all cases. 

Prior to MediGuide technology, the average CRT-D device implant fluoroscopy time was 22 minutes. In the first 20 implants post-MediGuide implementation, we yielded an average of 5.2 minutes per new implant. In 2015, our average fluoroscopy time per case dropped to 4.2 minutes; in 2016, it is now down to 3.2 minutes for new implants, failed implants, and studies that include alternative procedures (i.e., AV node ablation, lead extraction, etc.). This case study shows real promise for the future state of CRT-D device implants, as innovative technologies and clinical practice continue to evolve to make a minimal radiation environment more achievable.

Disclosures: The authors have no conflicts of interest to report regarding the content herein.   

References

1. Hsu JC, Badhwar N, Lee BK, Vedeantham V, Tseng ZH, Marcus GM. Predictors of fluoroscopy time and procedural failure during biventricular device implantation. Am J Cardiol. 2012;110(2):240-245.
2. Perisinakis KT, Theocharopoulos N, Damilakis J, Manios E, Vardas P, Gourtsoyiannis N. Fluoroscopically guided implantation of modern cardiac resynchronization devices: radiation burden to the patient and associated risks. J Am Coll Cardiol. 2005;46(12):2335-2359.