Real-World Evaluation of Magnetic Resonance Imaging in Patients With a Magnetic Resonance Imaging Conditional Pacemaker System: Results of 4-Year Prospective Follow-Up in 2,629 Patients.

OBJECTIVES: This global, multicenter, prospective study, initiated to meet U.S. Food and Drug Administration condition-of-approval requirements, evaluated the safety and efficacy of the Medtronic magnetic resonance imaging (MRI)-conditional pacing system when used in an MRI environment in routine clinical practice. The primary endpoint was MRI-related complications. The secondary endpoint was the cumulative change in pacing capture threshold (PCT) for patients undergoing multiple MRI scans. BACKGROUND: Large-scale, real-world evaluation of MRI in patients implanted with an MRI-conditional pacing system remains limited, with few published data for patients who undergo multiple MRI scans. METHODS: Patients were enrolled and followed up prospectively from the time of implantation. Evaluation of the pacemaker function was performed before and after MRI. The MRI-related complication-free rate was evaluated. Changes in electrical performance after each scan and cumulative changes over multiple scans were analyzed. RESULTS: In 81 centers, 2,629 patients were implanted with a complete SureScan pacing system (41.8% women, age 70.2 ± 12.5 years). A total of 526 patients (28.5%) received 872 clinically indicated MRI scans, including 58 thoracic scans. No MRI-related complications occurred during or after MRI, meeting the primary objective. Six (1%) MRI-related observations (atrial fibrillation, PCT increase, and chest symptoms) were reported. A total of 171 patients (32.5%) underwent 2 or more scans with no cumulative increase in PCT. CONCLUSIONS: This report constitutes the largest longitudinal MRI experience in patients implanted with an MRI-conditional pacing system. Results support the safety profile of the SureScan system and demonstrate for the first time that patients may safely undergo multiple MRI scans. (SureScan Post-Approval Study; NCT01299675).

Prolapsed double-canted bipolar left ventricular lead for pacing the left atrium via the coronary sinus: experience in 11 patients.

AIMS: High thresholds and frequent lead dislodgement limit pacing the left atrium (LA) from the mid to distal coronary sinus (CS). The aim of this report is to describe a method for and the results of prolapsing a double-canted bipolar lead into the mid-to-distal CS to eliminate lead dislodgement and improve pacing thresholds. METHODS AND RESULTS: After CS access the 9 Fr. anatomic sheath is withdrawn to the right atrium (RA) over an extra support wire. A double-canted bipolar lead is advanced into the RA until the proximal bend is outside the tip of the sheath. With the stylet withdrawn to the proximal bend, the sheath and lead are advanced over the wire back into the CS. The lead distal to the proximal bend is prolapsed beside the sheath as the tip of the sheath enters the CS. The lead was successfully prolapsed in 11 consecutive patients. In one patient, capture was >5 V in all locations. Of the 10 successful implants, the acute thresholds were: mean 1.53 V, median 1.35 V, range 0.4-4.0 V. Chronic thresholds were: mean 2 V, median 2 V range 0.4-4.0 V. There were no displaced leads or lead fractures through 6-10 months of follow-up. CONCLUSIONS: Prolapse of a commercially available double-canted bipolar passive fixation lead eliminates lead dislodgment and improves thresholds providing a means for permanent pacing of the LA from the mid to distal CS and provides the design principles for a dedicated lead.

Excimer laser to open refractory subclavian occlusion in 12 consecutive patients.

BACKGROUND: Ideally, new leads are placed via the axillary/cephalic vein on the same side as the initial implant; however, 3.6% to 9% of patients have chronic total subclavian/innominate occlusion. In most cases, a wire can be manipulated across the occlusion and venoplasty safely performed. Occasionally, a wire will not cross, and additional tools are required. OBJECTIVE: The purpose of this study was to evaluate our experience with an excimer laser catheter used to cross wire-refractory chronic total subclavian/innominate occlusion in 12 patients. METHODS: We first used the laser to successfully cross a lead-related chronic total occlusion that did not yield to either a wire or microdissection. We subsequently used the laser for 11 additional wire-refractory occlusions. We reviewed the implant reports, hospital records, and videos of each case. RESULTS: The occlusions were successfully crossed and a wire placed for venoplasty in 11 of 12 cases by one of three implanting physicians. No complications occurred, and the existing leads sustained no damage. CONCLUSION: Although the safety of the procedure remains uncertain, if directions are followed and are precautions heeded, physicians with training and experience in venoplasty and laser lead extraction can learn this technique, which provides an important option for adding a lead to an existing device when the ipsilateral access vein is occluded.

Clinical benefits of remote versus transtelephonic monitoring of implanted pacemakers.

OBJECTIVES: The purpose of this study was to evaluate remote pacemaker interrogation for the earlier diagnosis of clinically actionable events compared with traditional transtelephonic monitoring and routine in-person evaluation. BACKGROUND: Pacemaker patient follow-up procedures have evolved from evaluating devices with little programmability and diagnostic information solely in person to transtelephonic rhythm strip recordings that allow monitoring of basic device function. More recently developed remote monitoring technology leverages expanded device capabilities, augmenting traditional transtelephonic monitoring to evaluate patients via full device interrogation. METHODS: The time to first diagnosis of a clinically actionable event was compared in patients who were followed by remote interrogation (Remote) and those who were followed per standard of care with office visits augmented by transtelephonic monitoring (Control). Patients were randomized 2:1. Remote arm patients transmitted pacemaker information at 3-month intervals. Control arm patients with a single-chamber pacemaker transmitted at 2-month intervals. Control arm patients with dual-chamber devices transmitted at 2-month intervals with an office visit at 6 months. All patients were seen in office at 12 months. RESULTS: The mean time to first diagnosis of clinically actionable events was earlier in the Remote arm (5.7 months) than in the Control arm (7.7 months). Three (2%) of the 190 events in the Control arm and 446 (66%) of 676 events in the Remote arm were identified remotely. CONCLUSIONS: The strategic use of remote pacemaker interrogation follow-up detects actionable events that are potentially important more quickly and more frequently than transtelephonic rhythm strip recordings. The use of transtelephonic rhythm strips for pacemaker follow-up is of little value except for battery status determinations. (PREFER [Pacemaker Remote Follow-up Evaluation and Review]; NCT00294645).

Goose neck snare for LV lead placement in difficult venous anatomy.

Venous anatomy frequently impairs placement of the left ventricular (LV) lead. In some cases, the wire will not advance into the vein and in others wire position is lost as the lead is advanced. This article describes how a commonly available goose neck snare is used to gain access to the distal end of the wire as it re-enters the coronary sinus retrograde via collaterals through an adjacent vein. The snare is advanced into the coronary sinus through the same catheter as the wire. The snare opens perpendicular to the long axis of the coronary sinus due to which the wire must pass through the open loop, provided the diameter of the snare is approximately the same as the coronary sinus. Thus no time-consuming manipulation of the snare is required. With access to both ends of the wire the vein is approached either retrograde (over the distal end) or antegrade (over the proximal end) while the other end of the wire is secured by the operator. Gaining control of both ends of the wire with a snare is another example of adapting interventional techniques for the device implantation. Unlike venoplasty, the snare does not evoke credentialing concerns and can be easily implemented by most implanting physicians.

Focused force coronary venoplasty to eliminate a refractory stenosis preventing LV lead placement in two patients.

This report describes two patients who underwent a second attempt at cardiac resynchronization therapy (CRT) in the setting of a severe stenosis in the lateral coronary vein that prevented passage of a left ventricular lead. Both stenoses were unresponsive to standard noncompliant balloon dilatation but were successfully treated with the addition of a second stiff angioplasty wire beside the noncompliant balloon. Venoplasty with the addition of a side wire beside the balloon should be considered for resistant coronary vein stenosis encountered during CRT device implantation.

Coronary vein rupture during venoplasty for LV lead placement.

Coronary vein rupture is a potential complication of venoplasty for LV lead placement. Vein rupture in a patient with a virgin pericardium would be anticipated to have a profound hemodynamic impact from bleeding into the pericardial space. This report describes an elderly woman with a virgin pericardial space who underwent cardiac resynchronization therapy (CRT). Venoplasty of a lead limiting venous stenosis was performed on the lateral coronary vein. The stenosis was unresponsive to a standard noncompliant balloon with side wire. When the inflation pressure was increased beyond the rated burst pressure the balloon ruptured, perforating the vein. We describe our experience in successfully placing the left ventricular lead safely despite the problems arising from these circumstances.

Over the wire lead extraction and focused force venoplasty to regain venous access in a totally occluded subclavian vein.

INTRODUCTION: Venoplasty allows the addition or replacement of leads despite subtotal or total subclavian occlusion. METHODS: The threshold of the LV pacing lead implanted for biventricular pacing over a period of 18 months increased to greater than 5 V. A pre implant venogram revealed total subclavian occlusion. Venous access was maintained by extraction of the 4 F LV lead over a wire. Subsequently the sheath would not advance despite 6mm balloon inflation to 30 atm with no residual waist. A wire was placed beside the balloon and the balloon was reinflated. RESULTS: The subclavian obstruction was eliminated without damage to the existing leads. CONCLUSION: The obstruction formed by the fibrous track around an extracted lead may persist despite what appears to be successful balloon dilation. Inflation with a wire beside the balloon increases the effect eliminating the resistant obstruction without damaging the leads.

Prospective randomized comparison of cooled radiofrequency versus standard radiofrequency energy for ablation of typical atrial flutter.

In patients with atrial flutter, conventional RF ablation may not result in complete isthmus block. This prospective, randomized study tested the hypothesis that the cooled RF ablation is safe and facilitates the achievement of isthmus block with fewer RF applications than with standard ablation for typical atrial flutter. Isthmus ablation was performed in 59 patients (40 men, 64 +/- 14 years) with type I atrial flutter using standard RF (n = 31) or cooled RF (n = 28) catheters with crossover after 12 unsuccessful RF applications. The endpoint was bidirectional isthmus block or a total of 24 unsuccessful RF applications. After the first 12 RF applications, 17 (55%) of 31 standard RF and 22 (79%) of 28 cooled RF patients had bidirectional isthmus block (P < 0.05). After the remaining patients crossed over to the alternate RF ablation system and underwent up to 12 more RF applications, bidirectional isthmus block had been demonstrated in 27 (87%) of 31 standard RF and 25 (89%) of 28 cooled RF patients (P = NS). Isthmus block was not achieved within 24 RF applications in four standard and three cooled RF patients. Mean measured tip temperatures for cooled RF were lower than for standard RF (38.5 degrees C +/- 6.98 degrees C vs 57.2 degrees C +/- 7.42 degrees C, P < 0.0001). Peak temperatures were also lower for cooled RF compared to standard RF (45.7 degrees C +/- 22.7 degrees C vs 63.4 degrees C +/- 9.87 degrees C, P < 0.0001). Importantly, mean power delivered was significantly higher for cooled than for standard RF (42.3 +/- 9.48 vs 34.0 +/- 14.0 W, P < 0.0001). There were no serious complications for either ablation system. During a 12.8 +/- 3.76-month follow-up, there were two atrial flutter recurrences in the cooled RF group and four in the standard RF group (P = NS). In patients with type I atrial flutter, ablation with the cooled RF catheter is as safe as, and facilitates creation of bidirectional isthmus block more rapidly than, standard RF ablation.