The right ventricular outflow tract: a comparative study of septal, anterior wall, and free wall pacing

BACKGROUND: There is marked heterogeneity in right ventricular outflow tract (RVOT) pacemaker lead placement using conventional leads. As a result, we have sought to identify a reproducible way of placing a ventricular lead onto the RVOT septum. METHODS AND RESULTS: A major determinant is the shape of the stylet used to deliver the active-fixation lead. We compared stylet shapes and configurations in patients who initially had a ventricular lead placed onto the anterior or free wall of the RVOT and then had the lead repositioned onto the septum. All leads were loaded with a stylet fashioned with a distal primary curve to facilitate delivery of the lead to the pulmonary artery, then using a pullback technique the lead was retracted to the RVOT. All lead placements were confirmed by fluoroscopy and electrocardiography. Anterior or free wall placement was achieved by the stylet having either the standard curve or an added distal anterior angulation. In contrast, septal lead positioning was uniformly achieved by a distal posterior angulation of the curved stylet. This difference in tip shape was highly predictive for septal placement (P < 0.001). With septal pacing, a narrower QRS duration was noted, compared to anterior or free wall pacing (136 vs 155 ms, P < 0.001). All pacing parameters were within acceptable limits. CONCLUSION: Using appropriately shaped stylets, pacing leads can now be placed into specific positions within the RVOT and in particular septal pacing can be reliably and reproducibly achieved. This is an important step in the standardization of lead placement in the RVOT.     

Cardiac stimulation caused by biogalvanic current during pacemaker implantation

After lead positioning during implantation of a biventricular pacing system intermittent ventricular simulation was observed. There was no pacemaker connected to any of the leads, but ventricular capture could be provoked by an intermittent contact between the lead stylet, which was still partially inserted, and a self-retaining retractor. The same phenomenon was observed from the atrial lead.     

Single-lead VDD pacemaker implantation via persistent left superior vena cava: an improved technique and a new modality

Persistent left superior vena cava (PLSVC), which occurs in approximately 0.5% of the general population, may complicate pacemaker implantation by making lead insertion into the right ventricle more difficult and increasing lead instability when the transvenous approach is attempted. We describe our experience with four PLSVC patients with pacemakers. We developed an open J-loop technique in which the stylet tip is directed toward the orifice of the tricuspid valve anteroinferiorly. The lead was implanted into the right ventricular apex without difficulty. Three of our patients had high-degree atrioventricular block and received VVI pacemakers with the new technique. One patient with complete atrioventricular block received a single-lead VDD pacemaker by means of the same technique, with the paired electrodes positioned in the lower right atrium. Excellent results were obtained on exercise tolerance testing, 24-hour Holter monitoring, and echocardiographically determined systolic and diastolic function. This improved technique can simplify pacemaker implantation in patients with PLSVC. The VDD device is a new way to maintain systolic and diastolic function and is an appropriate option in patients with high-degree atrioventricular block and PLSVC who require pacemaker implantation.     

Guidance of cardiac pacemaker leads using real time 3D ultrasound: feasibility studies

We investigated the feasibility of the guidance of pacemaker lead implantation using the pacemaker lead stylet as an acoustic wave-guide combined with real time 3D ultrasound imaging. In one approach, with a 2.5 MHz transducer coupled to a stylet of a pacemaker lead, we used the stylet as a transmitter to track the vibrating tip in a 3D ultrasound scan. In another approach, we connected the stylet to a piezoelectric actuator vibrating in the range 0.5-5 kHz so that the tip of the stylet was imaged using the color Doppler feature of the real time 3D ultrasound scanner. In both approaches, tracking of the isolated stylet showed good accuracy. However, neither approach offered sufficient signal-to-noise ratio to detect the vibration within the lumen of an intact pacemaker lead.     

Pacemaker-mediated tachycardia in a biventricular pacing system

A 63-year-old man with chronic atrial fibrillation and heart failure had a biventricular pacing system implanted. The pulse generator was a standard DDDR pacemaker, using the atrial channel for the right ventricular lead and the ventricular channel for the left ventricular lead. During final adjustment of the pacing parameters, a pacemaker tachycardia triggered by T wave oversensing from the right ventricular lead was recorded.     

Ancillary tools in pacemaker and defibrillator lead extraction using a novel lead removal system

A previous report described our preliminary experience with a highly successful pacing lead removal system (VasoExtor). Extending this experience, we found it necessary to use additional tools to enhance the success of percutaneous lead extraction with this system. In the present series, we used the standard locking stylets (S and K), and recently, one newer type of stylet (Magic) over the last 3 years in 34 patients to extract 48 pacemaker leads in 31 patients and 3 defibrillator (ICD) leads in 3 patients. Lead extraction was carried out in 23 men and 11 women (aged 64 +/- 17 years) because of pacemaker infection (n = 21), pacemaker (n = 8) or ICD (n = 3) lead malfunction, or prior to ICD implant (n = 2). Leads were in place for 3.5 +/- 3.7 years. Infections, involving pocket and lead(s), were due to S. epidermidis (n = 13), S. aureus (n = 6), S. aureus plus E. coli (n = 1), for fungi (n = 1). Of the 48 pacing leads, 31 were ventricular, 15 atrial, and 2 were VDD leads. The ICD leads were two double-coil leads (CPI) and one single-coil lead (Telectronics). Using the S (n = 12), K (n = 8), or Magic (n = 3) stylets, all pacing leads in 23 patients and the ICD leads in 2 patients were successfully removed from a subclavian approach using the locking stylets. However, in nine (26.5%) patients ancillary tools were required. In four patients, lead fragments were captured with use of a noose catheter, a pigtail catheter, and a bioptome from a right femoral approach. In two patients, locking could not be effected and a noose catheter from the right femoral vein was used, aided by a pigtail and an Amplatz catheter and a bioptome to remove three leads. In a patient with an ICD lead, a combined subclavian (stylet S) and right femoral approach (noose catheter) was required. In a patient with a dysfunctional ventricular lead 12 years old, a motor drive unit was used to facilitate the exchange of locking stylets, but extraction failed. In another patient, a fragment of a dysfunctional ventricular lead remained intravascularly despite resorting to a femoral approach. Finally, lead removal was completely (32/34, 94%) or partially (1/34, 3%) successful in 33 (97%) of 34 patients for 50 (98%) of 51 leads without complications. In conclusion, to enhance the success of pacing or ICD lead extraction with use of the VascoExtor locking stylets, an array of ancillary tools were required in more than one fourth of patients.     

Spontaneous Twisting of an Implanted Pacemaker Electrode in Three Cases

We present three cases of an unusual pacing lead aberration occurring at different times after implantation. In the first patient, the electrode was twisted close to the pacemaker, and dislodgment occurred on the 40th postoperative day. In the second case, there was only proximal twisting of the electrode. In the third case the electrode was twisted in two places: proximal to the pacemaker, and distal, within the right atrium. The complication was managed successfully by reimplanting the same electrode after stiffening the lead near the generator with a portion of the stylet.     

Right Ventricular Septal Pacing: The Success of Stylet-Driven Active-Fixation Leads

Background: The detrimental effects of right ventricular (RV) apical pacing on left ventricular function has driven interest in alternative pacing sites and in particular the mid RV septum and RV outflow tract (RVOT). RV septal lead positioning can be successfully achieved with a specifically shaped stylet and confirmed by the left anterior oblique (LAO) fluoroscopic projection. Such a projection is neither always used nor available during pacemaker implantation. The aim of this study was to evaluate how effective is the stylet-driven technique in septal lead placement guided only by posterior-anterior (PA) fluoroscopic view.
Methods: One hundred consecutive patients with an indication for single- or dual-chamber pacing were enrolled. RV septal lead positioning was attempted in the PA projection only and confirmed by the LAO projection at the end of the procedure.
Results: The RV lead position was septal in 90% of the patients. This included mid RV in 56 and RVOT in 34 patients. There were no significant differences in the mean stimulation threshold, R-wave sensing, and lead impedance between the two sites . In the RVOT, 97% (34/35) of leads were placed on the septum, whereas in the mid RV the value was 89% (56/63).
Conclusions: The study confirms that conventional active-fixation pacing leads can be successfully and safely deployed onto the RV septum using a purposely-shaped stylet guided only by the PA fluoroscopic projection. (PACE 2010; 49–53)     

Three-Year Experience with a Stylet for Lead Extraction: A Multicenter Study

The extraction of chronically implanted and infected pacemaker and defibrillator leads is an important issue. This article describes the experience gathered between 1990 and 1994 by seven European centers regarding a locking stylet that is uniformly applicable for a wide variety of internal pacing coil diameters. This interventional locking stylet for lead extraction has an outer diameter of 0.4 mm (0.016 inches). The stylet consists of a hollow shaft in which an inner traction wire is embedded. At the tip of the inner traction wire an anchoring mechanism, which can be opened by retraction, is applied. Removal attempts were made for 150 leads, 110 in ventricular and 40 in atrial positions. Results : Complete removal was possible in 122 cases (81 %). Partial removal was possible in 18 cases (12%). Failure to remove the lead with the extraction stylet was experienced in 10 cases (7%). In seven patients, the leads were removed by cardiothoracic surgery; 3 defective leads were left in place. There were no serious complications associated with the procedure. None of the patients died. Conclusion : The experience with this extraction stylet for lead removal has shown good results. Despite a low complication rate thus far, each case for lead removal should be judged on the individual basis of benefit-to-risk ratio.     

Aortic perforation by active-fixation atrial pacing lead

This report describes perforation of the aorta related to the implantation of an active-fixation atrial pacing lead, a previously undocumented complication of pacemaker implantation. The complication was related to excessive tissue penetration by the screw at the tip of the lead or perforation of the lead body by the positioning stylet during manipulation whereupon the stylet traversed the atrial wall and aortic wall. Perforation of the aorta should be part of the differential diagnosis of cardiac tamponade after pacemaker implantation.     

Feasibility Of Temporary Biventricular Pacing In Patients With Reduced Left Ventricular Function After Coronary Artery Bypass Grafting

Background and Methods: Biventricular pacing improves hemodynamics after weaning from cardiopulmonary bypass in patients with severely reduced left ventricular (LV) function undergoing coronary artery bypass grafting (CABG). We examined the feasibility of temporary biventricular pacing for 96 hours postoperatively. Unipolar epicardial wires were placed on the roof of the right atrium (RA), the right ventricular (RV) outflow tract, and the LV free lateral wall and connected to an external pacing device in 51 patients (mean LV ejection fraction 35 ± 4%). Pacing and sensing thresholds, lead survival and incidence of pacemaker dysfunction were determined.
Results: Atrial and RV pacing thresholds increased significantly by the 4th postoperative day, from 1.6 ± 0.2 to 2.5 ± 0.3 V at 0.5 ms (P = 0.03) at the RA, 1.4 ± 0.3 V to 2.7 ± 0.4 mV (P = 0.01) at the RV, and 1.9 ± 0.6 V to 2.9 ± 0.7 mV (P = 0.3) at the LV, while sensing thresholds decreased from 2.0 ± 0.2 to 1.7 ± 0.2 mV (P = 0.18) at the RA, 7.2 ± 0.8 to 5.1 ± 0.7 mV (P = 0.05) at the RV, and 9.4 ± 1.3 to 5.5 ± 1.1 mV (P = 0.02) at the LV. The cumulative overall incidence of lead failure was 24% by the 4th postoperative day, and was similar at the RV and LV. We observed no ventricular proarrhythmia due to pacing or temporary pacemaker malfunction.
Conclusions: Biventricular pacing after CABG using a standard external pacing system was feasible and safe.     

Dizziness spells: Should one suspect the pacemaker?

A 52-year-old lady presented to the emergency department with recurrent episodes of dizziness and near-syncope on awakening up or swinging her left arm. Initial rhythm strips demonstrated intermittently non-conducted p waves corresponding to inappropriate pacemaker inhibition and oversensing malfunction. Pacemaker was interrogated in the ED showing ventricular lead noise and decreased lead impedance over a one year period. The patient was diagnosed with pacemaker lead failure supported by correlating pacemaker lead variation with homolateral arm movement. The patient was referred to an electrophysiologist and underwent new right ventricular lead placement with the resolution of symptoms.     

Atrioventricular membrane perforation: a very rare complication of transvenous pacemaker implantation.

A 63-year-old man was admitted to our emergency department with the complaint of syncope. An electrocardiogram showed complete atrioventricular block with a low ventricular rate. He was hospitalized and a temporary transfemoral pacemaker was inserted under direct fluoroscopy urgently. Immediate postprocedural electrocardiogram in the paced mode showed right bundle branch block morphology that led to suggestion of abnormal lead location. A transthoracic echocardiogram revealed that the pacemaker lead was directly inserted from the right atrium into the left ventricle through the junction of the interatrial and interventricular septums. Because severe multivessel coronary artery disease was diagnosed angiographically in his subsequent hospital course, coronary artery bypass grafting and surgical extraction of the misplaced lead was performed at the same time. Clinical implications, diagnosis, and therapeutic options of left ventricular pacemaker lead malposition are discussed.     

Left Heart Pacing and Cardioembolic Stroke

Three patients with inadvertently positioned left heart pacemaker leads were admitted for neurological symptoms consistent with embolic stroke. In one of them, the pacemaker lead crossed the interatrial septum, the mitral valve, and entered the left ventricle. In another it was erroneously placed through the subclavian artery, across the aortic valve, and into the left ventricular chamber In the third patient, the right ventricular lead of a DDD pacemaker was placed in the coronary sinus and the right atrial lead crossed the interatrial septum, and intermittently entered the left ventricular cavity. Once anticoagulation was initiated, symptoms resolved; they recurred when the level of anticoagulation dropped leading to a major stroke in one of the patients. Two of the patients were on aspirin at the onset of symptoms. We believe that every approach must be considered to remove the malpositioned lead. Otherwise, full dose anticoagulation must be initiated since antiplatelet therapy alone does not confer adequate protection against stroke.     

Transarterial Permanent Pacing of the Left Ventricle

Clinical evaluation of a 64-year-old male patient with a permanent pacemaker showed a right bundle branch block in his ECG that led to the suspicion of catheter misplacement. A two-dimensional echocardiogram and bilateral venogram demonstrated that the pacemaker lead was not in the venous system and that its course was from the axillary artery to the left ventricle passing through the aortic valve. Thirty-three days after implant, replacement of the pacemaker lead through the venous system to stimulate the right ventricular endocardium was performed. At 7 month follow-up the patient has had no complication from his previous arterial pacemaker implantation.     

An Innovation in Pacemaker Lead Implantation via Persistent Left Superior Vena Cava: The “3D Alpha Curve” Stylet

Persistent left superior vena cava (PLSVC) draining into coronary sinus is typically detected incidentally during transcatheter interventions using left subclavian venous approach. In our experience, we have encountered this anomaly on a few occasions and in all these cases we successfully implanted leads in the right ventricle (RV) by shaping the stylet into a “U‐shaped” or “pigtail‐shaped” curve. Herein, we report a case of an adult male who underwent successful dual‐chamber pacemaker implantation via PLSVC through left axillary venous approach. In this case, we were unable to deliver the lead into RV using aforementioned stylets. As an innovation, we used a “three‐dimensional alpha curve”‐shaped stylet that facilitated an easy entry of pacing lead into the RV.     

Biventricular Pacing Using Two Pacemakers and the Triggered VVT Mode

O'COCHLAIN, B., et al. : Biventricular Pacing Using Two Pacemakers and the Triggered VVT Mode. Pacemaker dependent patients exhibit interventricular conduction delay due to right ventricular lead placement. The addition of a transvenous coronary sinus lead for biventricular pacing has been shown to be effective. Venous stenosis and thrombosis postpacemaker implantation can occur in up to 35% of patients. This report describes a patient with a preexisting left-sided dual chamber pacemaker and chronic left subclavian vein occlusion that was upgraded to a biventricular system by placing a coronary sinus lead and single chamber ventricular triggered pacemaker on the opposite side.     

Cardiac pacing: memories of a bygone era

The first cardiac pacemaker implants occurred in the late 1950s and involved insertion of epicardial or epimyocardial leads and abdominal pulse generators. By the mid 1960s, cardiologists were making attempts to insert transvenous leads into the right ventricle. These early unipolar leads had large, polished, high polarization electrodes, no fixation device, and no lumen in which to place a stylet for lead positioning. The lead implantation procedures were usually long and the irradiation to both patient and operator excessive. Pulse generators were powered by zinc-mercury cells, which were large, unreliable, and prone to sudden output failure. Postoperative complications such as lead dislodgement, exit block, and premature power source failure were very common with most patients requiring further surgery within a year. Little has been written of this period and in particular the experiences of the operators, such that today's pacemaker implanters have virtually no knowledge of this bygone era. This historical report by four Australian cardiologists details the operative procedures and follow-up management of those original pacemaker recipients.     

The Right Ventricular Outflow Tract as an Alternative Permanent Pacing Site: Long-Term Follow-Up

The long-term characteristics of the right ventricular outflow tract have been assessed as an alternative permanent pacing site to the right ventricular apex. Thirty-three consecutive patients requiring ventricular pacing were randomized to be paced from one of the two sites. Pacing was performed using a screw-in lead, and a programmable pacemaker was used to facilitate threshold testing. There was no significant difference in the lead positioning time or any acute implant measurement (e.g., threshold at 0.5 msec 0.4 +/- 0.2 V for both sites, P = 0.99). Chronic measurements were also comparable during follow-up (mean 73 months) with a mean threshold at most recent follow-up of 0.15 +/- 0.2 msec (apex) and 0.13 +/- 0.21 msec (outflow tract) at 5 V, P = 0.81. There was only one pacing related complication, a lead dislodgment (outflow tract) in a pacemaker twiddler. Overall, both sites were highly satisfactory.     

The right ventricular outflow tract: the road to septal pacing

BACKGROUND: Pacing from the right ventricular apex is associated with long-term adverse effects on left ventricular function. This has fuelled interest in alternative pacing sites, especially the septal aspect of the right ventricular outflow tract (RVOT). However, it is a common perception that septal RVOT pacing is difficult to achieve. METHODS AND RESULTS: In this article, we will review the anatomy of the RVOT and discuss the importance of standard radiographic views and the 12-lead electrocardiogram in aiding lead placement. We will also describe a method utilizing a novel stylet shape, whereby a conventional active-fixation, stylet-driven lead can be easily and reliably deployed onto the RVOT septum.