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Endovascular revascularization of the femoropopliteal (FP) artery has been limited by high rates of restenosis and stent fracture. The unique physical forces that are applied to the FP artery during leg movement have been implicated in these phenomena. The foundation for measuring the effects of physical forces on the FP artery in a clinically relevant environment is based on the ability to develop 3D models of this vessel in different leg positions in vivo in patients with peripheral arterial disease (PAD). By acquiring paired angiographic images of the FP artery, and using angiography-based 3D modeling algorithms previously validated in the coronary arteries, the authors generated 3D models of ten FP arteries in nine patients with PAD with the lower extremity in straight leg (SL) and crossed leg (CL) positions. Due to the length of the FP artery, overlapping paired angiographic images of the entire FP artery were required to image the entire vessel, which necessitated the development of a novel fusion process in order to generate a 3D model of the entire FP artery. The methodology of angiographic acquisition and 3D model generation of the FP artery is described. In a subset of patients, a third angiographic view (i.e., validation view) was acquired in addition to the standard paired views for the purpose of validating the 3D modeling process. The mean root-mean-square (rms) error of the point-to-point distances between the centerline of the main FP artery from the 2D validation view and the centerline from the 3D model placed in the validation view for the SL and CL positions were 0.93±0.19 mm and 1.12±0.25 mm, respectively. Similarly, the mean rms error of the same comparison for the main FP artery and sidebranches for the SL and CL positions were 1.09±0.38 mm and 1.21±0.25 mm, respectively. A separate validation of the novel fusion process was performed by comparing the 3D model of the FP artery derived from fusion of 3D models of adjacent FP segments with the 2D validation view incorporating the region of fusion. The mean rms error of vessel centerline points of the main FP artery, the main FP artery plus directly connected sidebranches, and the mean rms error of upstream, downstream, and sidebranch directional vectors at bifurcation points in the overlap region were 1.41±0.79 mm, 2.13±1.12 mm, 3.16±3.72°, 3.60±5.39°, and 8.68±8.42° in the SL position, respectively, and 1.29±0.35 mm, 1.61±0.78 mm, 4.68±4.08°, 3.41±2.23°, and 5.52±4.41° in the CL position, respectively. Inter- and intraobserver variability in the generation of 3D models of individual FP segments and the fusion of overlapping FP segments were assessed. The mean rms errors between the centerlines of nine 3D models of individual FP segments generated by two independent observers, and repeated measurement by the same observer were 2.78±1.26 mm and 3.50±1.15 mm, respectively. The mean rms errors between the centerline of four 3D models of fused overlapping FP segments generated by two independent observers, and repeated measurement by the same observer were 4.99±0.99 mm and 5.98±1.22 mm, respectively. This study documents the ability to generate 3D models of the entire FP artery in vivo in patients with PAD in both SL and CL positions using routine angiography, and validates the methodologies used. [ABSTRACT FROM AUTHOR]

Telemetry of programmed and measured data in pacing pacing system evaluation and follow-up. Telemetry of programmed and measured data is an important feature of many pacemakers currently used in clinical practice. The ability to receive non-invasive data from the implanted dance constitutes a major advantage for the long-term follow-up of the patients and of device performance. There are numerous types of data retrievable via telemetry: parameters of device characteristics (output, battery longevity, impedance, etc), event recorders or counters, event markers, and endocardial electrograms. Ideally, this information should be beneficial in the longitudinal surveillance of modern pacemakers. [ABSTRACT FROM AUTHOR]

Although the purported incidence of pacemaker syndrome according to the literature is only 5%-15%, this is based on a series of patients with VVI pacing. Increasing numbers of studies are being reported in which patients prefer the dual chamber mode despite little benefit being demonstrated on objective testing, suggesting that pacemaker syndrome may be more common than is generally reported. This study was designed to evaluate the reported symptoms in a series of patients programmed to both the VVI and one or more dual chamber modes. Forty unselected patients with dual chamber pacemakers were entered into a blind, randomized trial comparing the symptoms associated with VVI pacing to those associated with dual chamber pacing. Patients were randomized to either VVI or dual chamber pacing. At the end of 1 week, questionnaires rating 16 different symptoms were completed. Blood pressure, LV function, presence of ventriculoatrial conduction, and ability to override the pacemaker were evaluated. The pacemaker was then programmed to the other mode. Overall, 12 of 16 symptoms were significantly worse in the VVI as compared to dual chamber mode. The most highly significant (P < 0.005) were shortness of breath, dizziness, fatigue, pulsations in the neck or abdomen, cough! and apprehension. Pacemaker syndrome was clinically recognized in 83% of patients paced in the VVI mode with 65% of patients experiencing moderate to severe symptoms. There were no readily identified clinical. hemodynamic, or electrophysiological parameters that predicted which patients would develop pacemaker syndrome. Thus, when patients have an opportunity to experience both pacing modes in close proximity to one another, there is a high incidence of pacemaker syndrome in the VVI mode. [ABSTRACT FROM AUTHOR]

Reliable atrial sensing of intrinsic P wave activity is important to ensure optimal atrial or dual chamber pacemaker function. Various physical factors (e.g., posture, respiration, exercise) may influence P wave characteristics and impair adequate sensing. To investigate this phenomenon, we measured the average of three P wave amplitudes (PWA) and calculated slew rates from telemetered printouts acquired from Pacesetter pace-makers in 32 patients. These measurements were performed in various body positions, with upright exercise and in varying stages of respiration. Results: the mean supine PWA increased on full inspiration (3.56 ± 1.3 mV versus 3.25 ± 1.2 mV during quiet respiration, P < 0.001), and also increased significantly with full expiration. The mean PWA increased on assuming the erect position (3.25 ± 1.2 mV increasing to 3.49 ± 1.3 mV, P < 0.001); in the upright position, the mean erect PWA during quiet respiration was not significantly influenced by the stage of respiration. The mean upright exercise PWA did not differ significantly from the preexercise erect PWA (3.50 ± 1.2 with exercise, and 3.47 ± 1.5 before exercise; P = NS). Calculated slew rates were not different lying versus standing. Conclusions: the mean supine PWA increases significantly at the extremes of respiration and on assuming the erect body position; upright exercise results in no appreciable change in the erect PWA. Atrial sensitivity adjustments based on standard supine testing should be adequate for all body positions. [ABSTRACT FROM AUTHOR]

The endocardial atrial electrogram or "P wave amplitude" (PWA) and pacemaker atrial stimulation thresholds are important parameters determining correct pacing system function. Pacemaker lead fixation mechanism and lead age may negatively influence these parameters. Therefore, we compared acute and chronic PWA and atrial stimulation thresholds in 33 patients with permanent transvenous atrial screw-in leads, follow-up 647 days ± 297 days; and in 31 patients with nonscrew leads, follow-up 855 days ± 512 days (P = ns). Results: The PWA differed between the two lead types acutely (1.97 mV ± 0.8 mV for screw-in versus 2.48 mV± 1.1 mV for nonscrew-in leads; P<0.05), but not chronically (2.21 mV ± 0,8 mV vs 2.2 mV± 3.2 mV; P = ns). Acute and chronic atrial pacing thresholds did not differ between groups. We also analyzed an early interim PWA in a subgroup of patients (mean 31 days after implantation). The nonscrew fixation group interim PWA was 1.76 mV ± 0.9 mV versus 2.7 mV ± 1.2 mV at implant (P < 0.001). The screw-in lead interim PWA was 2.04 mV ± 0.9 mV versus 1.97 mV ± 0.7 mV at implant (P = ns). Conclusions: (1) A significantly higher endocardial PWA occurs at the time of lead implantation in nonscrew versus screw-in lead groups, hut the chronic PWA does not differ between (he two groups. (2) A transient but marked early (mean approximately 31 days) attenuation of the PWA occurs only with nonscrew-in leads, (3) Atrial threshold stimulation energies do not differ between the two lead groups acutely or during follow-up. [ABSTRACT FROM AUTHOR]

Refractory supraventricular tachyarrhythmias may he both difficult and costly to control medically and can interfere with the patient's lifestyle. Newer treatment modalities are available for their management, and these require comprehensive assessment. We therefore compared costs and selective indices of patient benefit in a group of 17 patients in whom an atrial antitachycardia (Intermedics Intertach 262–12) pacemaker was placed for refractory supraventricular tachyarrhythmias. Prior medical therapy was compared to subsequent automatic antitachycardia pacemaker treatment. The total medical costs (admissions, emergency room visits, office visits, and medication costs) and the number of hospitalizations and medications were compared prior to implantation (F/U 69.3 ± 61 months) and after implantation (F/U 15.3 ± 7.8 months). A detailed quality-of-life questionnaire was also obtained 36.6 ± 11 months after implantation. Results: There were significant per patient differences in total cost before and after implantation: monthly costs were $505 ± $833 before pacemaker implantation and $105 ± $117 monthly afterward (P < 0.005). Pacemaker implantation hospitalization costs were $19,063 ± $8,362. Monthly medication costs averaged $46 before versus $15 after implantation (P < 0.01). The number of medication types also differed with an average 5.5 medication types per patient before versus 1.2 after implantation (P < 0.001]. There were 8.6 yearly hospital admissions in the whole group before implantation, versus 4.7 admissions in the group per year thereafter. Patients demonstrated significant improvement in 80% of the quality-of-life parameters studied. Conclusion: Adjunctive atrial automatic tachycardia-reversion pacemaker therapy may be cost-competitive over time when compared to medical therapy alone in patients with refractory supraventricular tachyarrhythmias and appears to improve overall quality-of-life. [ABSTRACT FROM AUTHOR]

The physiological benefit of rate responsive, single-chamber cardiac pacing is well documented. We studied the activity response of nine atrially placed Activitrax II pacemakers. Seven patients were noted to have an inadequate activity-rate response with maximal pacing rates of 85 to 101 beats/min. Marker Channel™ analysis revealed that the upper rate timeout was reset by far-field R wave sensing, even when sensing occurred in the atrial refractory period. These 9 pacemakers were tested by atrial sensitivity adjustment for ability to exclude far-field R wave sensing, while preserving P wave sensing. Unipolar implantation data were then examined for predictors of this differential far-R and P-wave sensing. Differential atrial sensing occurred in 4/9 pacemakers (2/2 bipolar in the right atrial appendage; 0/1 bipolar in the coronary sinus; and 4/9 unipolar). An empirically developed index utilizing unipolar implant parameters discriminated outcomes for 8/9 unipolar pacemakers. We conclude that: (1) the rate responsiveness of the atrial Activitrax II pacemaker is limited by far-field R wave sensing even when this occurs during atrial channel refractoriness; (2) reprogramming atrial sensitivity to differentially sensed P and far-field R waves may restore appropriate rate responsiveness; and (3) although a unipolar implant discriminant index may correctly identify adequacy of future rate responsiveness, the atrial application of the Activitrax II pacemaker is cautioned until further validation is forthcoming, particularly when used in unipolar and coronary sinus applications. [ABSTRACT FROM AUTHOR]

The P wave amplitude (PWA) plays an important role in determining atrial sensing capabilities. To assess earl PWA change. we compared the unipolar PWA in 43 patients at the lime of atrial lead placement, measured by a pacing systems analyzer, to the unipolar PWA recorded at the end of pacemaker surgery, from telemetered atrial endocardial electrograms. Individual PWA varied from a decrease of 5.2 mV to an increase of 2 mV (-63% to 267%). In 33 patients with active fixation leads, the implant PWA Was 1.96 ± 0.99mV versus 2.4 ± 1.4 mV after surgery. In ii patients with passive fixation leads, the implant PWA was 2.8 t 1.9 mV versus 1.9 ± 0.8 mV after surgery. The PWA change measared as the difference between the postsurgical and implant PWA Was 0.43 ± 0.8mV in active versus -0.86 + 1.6 mV in the passive fixation lead groups (P < 0.05). Considerable change in individual P wave amplitude can therefore occur very cork' utter pacemaker implantation. The direct ion differs significant' between active (predominantly positive) and passive fixation groups (pre- dominantly negative). These data suggest that an adequate margin of safety is important when initially programming atrial sensitivity, particularly when using passive fixation leads. [ABSTRACT FROM AUTHOR]

A 73-year-old male required a permanent pacemaker for complete heart block. After placement of the dual-chamber pacemaker, the patient developed random, repetitive ventricularly paced coupling at the upper rate limit. The diagnosis made from the surface electrocardiography was one of ventricular tracking of occult (T wave obscured) atrial ectopic activity. Examination of the telemetered atrial electrogram (EGM) revealed a diagnosis of intermittent far-field atrial sensing of the terminal ventricular depolarization. The value of obtaining an atrial electrogram during dual-chamber pacing is discussed. [ABSTRACT FROM AUTHOR]

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The potential benefits of pacing systems which restore A–V synchrony have long been recognized. However, availability of atrial leads which are easily implanted and which consistently perform well has been limited. A new version of the silicone rubber tined J leads is now available. Changes were made in the insulation material, conductor configuration, tine configuration, and a J memory coil was added. After over three years of use in 100 patients, we conclude that these leads are easier to implant than previous atrial leads, and that they demonstrate excellent clinical performance. [ABSTRACT FROM AUTHOR]

KASRAVI, B.,et al.: Coronary Sinus Lead Extraction in the Era of Cardiac Resynchronization Therapy: Single Center Experience. As the number of coronary sinus (CS) lead implantations for cardiac resynchronization therapy increases so will the need for extraction of these leads. The safety of extraction of leads from the branches of the CS has not been reported. We reviewed our database of patients undergoing pacemaker lead extraction from January 2002 through February 2004 at our institution. Of 149 patients referred for lead extraction, 14 (9%) had a biventricular device. The indications for lead extraction were infection, lead malfunction, and exit block. The duration of CS lead implants ranged between 2 and 43 months (mean 17 months). All 14 CS leads were removed successfully using nonsurgical lead extraction techniques. Three leads that were in place the longest (≥27 months) were removed via the femoral vein approach due to fibrous attachment of the CS lead body to the other pacemaker leads. The leads were structurally intact and without any significant fibrosis of their tips upon visual inspection. There were no major complications of CS laceration, hypotension, pericardial effusion, or excessive blood loss associated with any of the extraction procedures. CS leads were removed safely, successfully and with relative ease based on our experience in this small cohort of patients.(PACE 2005; 28:51–53) [ABSTRACT FROM AUTHOR]

Two cases of malpositioned LV electrodes are presented. Transesophageal echocardiography (TEE) allowed for a careful inspection of left-sided leads and for tracking their course. One LV and two right-sided leads were safely retrieved with TEE monitoring. One chronic LV lead was left in place as it was heavily fibrosed. TEE was helpful in the inspection and monitoring of the extraction and also in guided traction efforts. This is the first published report of echocardiographic visualization of the lead retrieval procedure. [ABSTRACT FROM AUTHOR]