Right Hemidiaphragmatic Twitching: A Complication of Bipolar Atrial Pacing

A patient with an atrioventricular sequential pacemaker developed rhythmic contractions of the right hemidiaphragm. This was found to be the result of right phrenic nerve stimulation, which was directly related to the wide distance between the poles of an ELA atrial lead when pacing in bipolar mode. Pole separation in current atrial leads is discussed.     

Inadvertent But Asymptomatic Right Atrial Perforation with Epicardial Pacing in a Neonate: A Rare Complication of Temporary Transvenous Cardiac Pacing

We report a case of an asymptomatic right atrial perforation due to temporary cardiac pacing in a neonate.     

Backup Right Ventricular Pacing with a 0.035" Guidewire during Implantation of Left Ventricular Leads

Introduction: During implantation of biventricular devices, manipulation of the guiding sheath during localization of the coronary sinus (CS) ostium may result in injury to the right bundle and complete heart block. A preventive measure is to implant the right ventricular (RV) lead first, though this may interfere with manipulation of the guiding sheath and dislodge the permanent lead . We tested the feasibility of backup pacing with a 0.035" guidewire, advanced through the guiding sheath during CS localization.
Methods: One hundred six consecutive patients (mean age = 70 ± 11 years, 81 men) undergoing biventricular device implantation were studied. A 0.035" guidewire with an uncoated tip was advanced into the right ventricle through the guiding sheath, and unipolar capture threshold, R-wave sensing amplitude, and pacing impedance were measured.
Results: RV pacing was successful in all patients. The mean capture threshold was 3.8 ± 2.1 V/0.5 ms, R-wave amplitude 5.4 ± 4.3 mV, and pacing impedance 226 ± 78 Ω. No arrhythmia was observed during the tests. Two patients developed complete heart block during the implant procedure and were successfully paced temporarily using the 0.035" guidewire.
Conclusion: Temporary RV pacing, using a 0.035" guidewire within the guiding sheath, is a simple, reliable, and safe method that allows backup pacing in case of traumatic complete heart block, developing during the implantation of biventricular devices.     

Single Center Experience with Femoral Extraction of Permanent Endocardial Pacing Leads

Between March 1995 and June 1997, 128 leads were extracted from the hearts of 28 women and 50 men, 69 +/- 15 years of age (mean +/- SD, range 22-92 years). The indications for the procedure were: Accufix leads in 18 patients (14%), dysfunction or incompatibility with ICD in 16 (12%), endocarditis on the lead in 41 (32%), pulse generator pocket infection in 28 (22%), and pulse generator and/or lead erosion in 25 patients (19%). The extraction was performed with a snare (lasso), via a femoral vein as a first approach in 116 leads, and as an alternate approach, after extraction from the original site of implantation had failed, in 12 leads. The leads had been implanted for 62 +/- 48 months (range 1-205 months). A Cook sheath was used in 7, and a femoral approach traction in 20 instances. Of the 128 leads, 122 (95%) were completely extracted, and 2 (2%) were partially extracted (the distal electrode remaining attached to the myocardium), and 4 (3%) could not be removed. Four complications occurred: 2 tears of the tricuspid valve without clinical consequences, one separation of the lead's distal electrode which migrated into the hypogastric vein, and one hemorrhage at the femoral puncture site. There was no death or serious complication caused by lead extraction in this series.     

The Diagnosis of Right Ventricular Perforation by an Endocardial Pacemaker Electrode

The diagnosis of right ventricular perforation by an endocardial pacemaker electrode should be suspected when failure of pacing occurs without electrode displacement. Although a number of changes occur on the standard electrocardiogram (ECG), none of these are diagnostic. The intracardiac electrogram performed during electrode withdrawal is not only diagnostic of perforation but can also aid in electrode positioning. Two case reports highlight these changes in the intracardiac electrogram. The first case also illustrates that, with electrode perforation, the ability to sense the intrinsic intracardiac electrical activity may be retained.     

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)     

Late Sensing Due to Extremely Delayed Right Ventricular Activation in Arrhythmogenic Right Ventricular Cardiomyopathy

A patient with arrhythmogenic right ventricular cardiomyopathy/dysplasia, implanted with a dual-chamber implantable cardioverter-defibrillator programmed in DDD mode, showed an unexpected ventricular sensing dysfunction: despite a very long (320 ms) programmed atrioventricular (AV) interval, ventricular stimuli were delivered in the ST segment after each spontaneous conducted QRS complex. This suggested the presence of ventricular undersensing. When, however, the system was programmed in VVI mode, spontaneous QRS complexes were normally sensed, although electrogram (ECM) analysis revealed that ventricular sensing occurred 160 ms after the beginning of QRS complex. A new ventricular lead was then implanted in the outflow tract of the right ventricle, resulting in normal ventricular sensing function. At the time of intervention, the amplitude of the spontaneous ventricular signal recorded from the old ventricular lead was 2.8 mV. In this patient, no true undersensing occurred although ventricular stimuli were delivered 140 ms after the beginning of spontaneous QRS complexes when the system was in DDD mode: the cause of the apparent pacemaker malfunction was the extremely prolonged ventricular depolarization. Due to fibrofatty muscle replacement, the depolarization wavefront reached the ventricular muscle surrounding the pacemaker lead with such a delay that at the end of the programmed sensed AV interval (320 ms) the ventricular EGM had not yet attained the sensing threshold. This apparent undersensing should, thus, be defined as "late sensing."     

Lead Dislodgment of a Permanent Pacemaker Due to Removal of a Temporary Pacing Electrode

A 63-year-old male received a transvenous temporary pacemaker for bradyarrhythmia following mitral valve replacement and tricuspid valve annuloplasty. A transvenous permanent pacemaker was implanted the following day due to persistence of the bradyarrythmia and pacemaker dependency of the patient. Later the same day during removal of the temporary pacing electrode the permanent pacing lead was dislodged and had to be operatively repositioned. To avoid this complication, the position of pacemaker leads should be checked postoperatively with a frontal and lateral chest radiograph, and fluoroscopy should be used during removal of a temporary lead.     

Evaluation of Temporary Atrial Pacing Leads

Thirty-five patients were randomized to receive either the Medtronic 6500 or one of two braided multifilament temporary pacing leads in the atrium following open heart surgery. Sensing performance was judged by amplitude, slew rate, and the proportion of patients with an adequate sensing threshold. Pacing performance was assessed with measures of impedance, threshold voltage, current, and energy. The Medtronic 6500 demonstrated superior sensing and lower energy consumption compared to braided multifilament leads. This type of lead may offer advantages when using atrial synchronous temporary pacing systems.     

Permanent Left Ventricular Pacing With Transvenous Leads Inserted Into The Coronary Veins

This paper describes a preliminary experiment - conducted jointly by 2 centers - of permanent left ventricular pacing using leads inserted by the transvenous route and through the coronary sinus into the cardiac veins of the left ventricle free wall. The aim was to obtain permanent biventricular pacing in a totally endocavitary configuration in pattents with severe LV dysfunction and drug-refractory heart failure. Two types of leads were used: nonspecific unipolar leads at the beginning of the experiment, followed by leads specifically designed to be used in the coronary sinus in a second step. The electrode could be fitted in an adequate location in 35 of the 47 patients (75.4%), with a 1.15±0.7 V acute pactng threshold and 11.8±5.7 mV R wave amplitude. The success rate was significantly higher with the specific electrodes (81.8% vs 53,3%, p < 0.001). The pacing and sensing thresholds upon implantation were not influenced by the type of lead or by the localization of the cardiac vein that was catheterized (great cardiac vein, lateral vein, postero-lateral or posterior vein, mid cardiac vein). In contrast, the pacing threshold was significantly lower (0.8 ± 0.2 vs L8 ± 0.8 V; p = 0.002) and the R wave amplitude tended to be greater (13.1 ± 4.5 mV vs 9.3 ± 6.5 mV; p = 0.07) when the tip electrode could be inserted distally into the vein, by comparison with a proximal site near the ostium. At the end of follow-up (10.2 ± 8.7 months), 34 out of the 35 leads were still fully functional, with a chronic pacing threshold of 1.8 ± 0.7 V and a R wave amplitude of 10.7 ± 6 mV. To conclude, permanent LV pacing via the transvenous route is possible in most patients, with excellent safety and long-term results.     

Inadvertent Transarterial Pacemaker Insertion: An Unusual Complication

We describe an unusual complication of pacemaker treatment in a patient who died after a replacement operation. In a difficult situation in which a functioning pacemaker was highly desirable and in which most of the available veins had already been used, the pacemaker electrode was inserted, by mistake, through a small artery. This was not detected by fluoroscopy during surgery. The postoperative X-ray examination seemed to indicate that the electrode tip was located in the coronary sinus, but the subsequent autopsy revealed it to be located in the left ventricle.     

Perforation of the Right Ventricle by Transvenous Defibrillator Leads: Prevention and Treatment

A series of 78 consecutive implants of the transvene PCD (Medtronic, Inc.) defibrillator system is presented and the occurrence of right ventricular perforation in 4 patients reported (5.2%). Diagnosis of perforation is made using four signs: (1) decrease in arterial blood pressure without any other explanation; (2) decrease in pulsatility of the cardiac silhouette as monitored by fluoroscopy; (3) increased size of the cardiac silhouette; and (4) abnormal position of the transvenous lead too far out toward the left ventricle along the pericardial outline. Perforation causes rapid and dramatic cardiac tamponade due to the large diameter and stiffness of the coil carrier lead. Immediate drainage of the hemopericardium must be carried out using the transxiphoid approach. The use of a thin blue-coded lead stylet (0.014-inch gauge) is recommended over the stiffer maroon-coded stylet. Since treatment must be carried out immediately, it is advised that a surgeon either perform, assist, or be immediately available whenever one of these systems is implanted.     

Inferolateral Myocardial Perfusion Defect Caused by Right Ventricular Outflow Tract Pacing

This case report describes a patient who was free of coronary artery disease and showed reversible inferolateral myocardial perfusion defect after having undergone a permanent dual chamber pacemaker implantation and an active-fixation ventricular lead insertion in the right ventricular outflow tract. (PACE 2004; 27[Pt. I]:808–811)     

Electrocardiographic Diagnosis of Biventricular Pacing in Patients with Nonapical Right Ventricular Leads

Background: Assessment of left ventricular (LV) capture is of paramount importance in patients with biventricular (BiV) pacing. Our goal was to identify electrocardiographic features that differentiate between BiV and right ventricular (RV)‐only pacing in patients with nonapical RV leads. Methods: The study enrolled 300 consecutive patients with BiV devices and nonapical RV leads, and obtained from them 558 electrocardiograms with either BiV pacing (n = 300) or RV‐only pacing (n = 258). RV pacing served as a surrogate for loss of LV capture. Electrocardiograms from the first 150 patients were used to identify BiV‐specific features, and to construct an algorithm to differentiate between BiV and RV‐only pacing. Electrocardiograms from the second 150 patients were used to validate the algorithm. Results: The following electrocardiographic features typical of BiV pacing were identified: QS in lead V6 (specificity = 98.7%, sensitivity = 54.7%), dominant R in lead V1 (specificity = 100%, sensitivity = 23.3%), q in lead V6 (specificity = 96%, sensitivity = 22.7%), and a QRS < 160 ms (specificity = 100%, sensitivity = 66.0%). The algorithm based on those features was found to have an overall diagnostic accuracy of 95.0%, a specificity of 96.0%, and a sensitivity of 93.5%. Conclusions: The study identified QRS features that were very specific for BiV pacing in patients with nonapical RV leads. Sequential arrangement of those features resulted in an algorithm that was very accurate for differentiating between BiV pacing and loss of LV capture. (PACE 2012; 35:1199–1208)     

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.     

Activated Pyrolytic Carbon Tip Pacing Leads: An Alternative to Steroid-Eluting Pacing Leads?

Pyrolytic carbon technology is known for its excellent mechanical properties and electrical conductivity; it is particularly biocompatible and does not require high production costs. The Sorin S100/4 lead is a ventricular passive fixation lead with a hemispherical electrode surface area of 4 mm²; the stimulating tip is made of a graphite core coated by a thin activated pyrolytic carbon layer. We evaluated the acute and medium-term performance of the unipolar version of this lead in 65 patients. At implantation, pacing threshold (at 0.5 ms) was 0.26 ± 0.08 V; pacing impedance (at 5 V and 0.5 ms) was 537 ± 94 Ω and Ft wave amplitude was 15.0 ± 5.5 mV. No lead related complications (dislodgment, perforation, exit block, etc.) occurred in any patient; one patient presented with a wire fracture after 26 months, due to subclavian crush syndrome. Follow-up procedures were performed at 1 week, and 2-, 10-, 18-, and 30-months postimplant. Since the leads were connected to pacemakers from different manufacturers, either voltage or duration thresholds were measured, In approximately two thirds of the patients, with an output of 2.5 V, a mean duration threshold of 0.16 ± 0.13 ms at 1 week, 0.12 ± 0.08 ms at 2 months, 0.11 ± 0.06 ms at 10 months, 0.09 ± 0.06 ms at 18 months, and 0.07 ± 0.03 ms at 30 months, was measured. In the remaining one-third of the patients, a comparable voltage threshold trend was measured. The mean pacing impedance showed a transient drop at 1 week, and then increased to a plateau of about 600 fl reached after 10 months. No sensing defect occurred in any patient. Our data show good acute and intermediate-term results of the S100/4 lead; the early rise in threshold was remarkably blunted. Activated pyrolytic carbon tip leads might therefore be considered as a possible, inexpensive alternative to steroideluting leads.