Implantable Transvenous Pacing Leads:

With the dawn of a new millennium, physicians' demands for very thin transvenous leads able to be positioned in nontraditional sites like the Bachmann's bundle, the high and mid-right ventricular septum, and the His bundle have created new and exciting challenges for lead engineers. Bipolar leads can now be as thin and reliable as unipolar leads. Cathode electrodes are very small, porous, and demonstrate high impedance. To optimize stimulation thresholds, steroid-eluting passive- and active-fixation electrodes have become popular for use in the atrium and ventricle. To create thin lead body diameters, new insulation and conductor materials and lead body designs are necessary. Hybrid medical materials having the best features of silicone rubber and polyurethane will allow for reliable insulation. Conductor cables instead of helical coils permit strong thin diameter leads to be designed. Transvenous lead implantation using the traditional stylet may not be possible with thin diameter leads, necessitating the use of sophisticated workstations using steerable catheters to guide these new active-fixation leads to selective sites in the right heart. The pacing lead of the future may be very different from the one used today. Ironically, it will have features and implantation techniques similar to the transvenous leads designed prior to the use of the stylet. We are now approaching full circle in lead development, retracing the footprints of the early implanters of three and a half decades ago. (PACE 2004; 27[Pt. II]:887–893)     

Detection of Atrial Fibrillation by Implanted Devices with Wireless Data Transmission Capability

Remote telemetry may facilitate the management of implantable devices. We tested the reliability of a new automatic, wireless home monitoring (HM) system that archives data every 24 hours. We retrospectively analyzed archival data from 276 consecutive pacing system implants to define temporal atrial fibrillation (AF) patterns and associated ventricular rate. An "AF day" was defined by a >20%/24 hour mode switch (MS) duration, irrespective of the MS number. Management decisions resulting from transmissions were noted. A pilot study confirmed that 89% of 22,356 transmissions were successful, of which >90% were received in <5 minutes. Data integrity was 100% preserved. Overall, AF developed in 29 patients (10.5%), representing a total of 645 AF days (mean = 22.2 ± 29.6 AF, median = 9 days), over 12 ± 2 months of monitoring. AF was infrequent (50% of 24 hours. Ventricular rates during 645 AF days in 29 patients averaged 95.1 ± 9.9 beats/min (median = 94 beats/min). Ventricular rates were >80 beats/min in 25 ± 30 AF days (median = 11 days). HM enabled rapid anticoagulation decisions. In recipients of implantable devices, automatic wireless telemetry with HM was efficient and reliable. Its application may overcome some current challenges in AF management by early notification and precise measurement of both AF burden and ventricular rate during AF.     

围术期糖尿病与心血管病相关性研究及处理进展

糖尿病是心血管病重要的独立高危因素。糖尿病增加心肌缺血损伤的危险性，引起心肌本身和心肌内小血管病变，抑制心肌缺血预处理的作用。现就糖尿病对心血管病的影响及糖尿病病人围术期的处理进展作一综述。     

不同临床和病理分型对肝门部胆管癌切除术预后的影响

目的 研究临床和病理分型与肝门部胆管癌切除术疗效的关系。方法总结1993年至2004年在解放军总医院肝胆外科手术切除的肝门部胆管癌198例病例资料。结果临床分型Ⅰ型34例，Ⅱ型60例，Ⅲa型27例，Ⅲb型33例，Ⅳ型19例，Ⅴa型6例。Ⅴb型19例。病理高分化腺癌35例，中分化腺癌52例，低分化腺癌54例，三者的中位生存期分别为29．5、11、5．5个月；病理切缘阴性者与切缘阳性者生存率有显著性差异（P 〈0．05）。手术并发症出现率41．4％，围手术期死亡1例。结论肝门部胆管癌根据临床分型进行相应的手术治疗；病理切缘阴性是影响预后的主要因素之一；围手术期正确处理，是减少手术并发症，提高患者生活质量和延长生存期的关键。     

Peak Endocardial Acceleration-Based Clinical Testing of the "BEST" DDDR Pacemaker

The peak endocardial acceleration (PEA, unit g) shows a near correlation with myocardial contractility during the isometric systolic contraction of the heart (dP/dtmax), with sympathetic activity and, thus, with physiological heart rate modulation. The (Biomechanical Endocardial Sorin Transducer (BEST) sensor is incorporated in the tip of a pacing lead and measures PEA directly near the myocardium. In an international study, the lead was implanted with the dual chamber pacemaker Living-1 (Sorin) in 105 patients. The behavior of the PEA signal was tested under conditions of physical and mental stress and during daily life activities by 24-hour recordings of PEA (PEA Holter) at 1 to 2 months and approximately 1 year after implantation. Implantation of the BEST lead was performed without complications in all patients. The sensor functioned properly in the short- and long-term in 98% of patients. Although PEA values differed from patient to patient, the values closely reflected the variations in sympathetic activity due to physical and mental stress in each patient. During exercise and during daily life activities a close correlation between PEA and heart rate was observed among patients with normal sinus rhythm. Peak endocardial acceleration allows a nearly physiological control of the pacing rate.     

Atypical Form of the Fourth Criterion for Transient Entrainment

The typical fourth criterion for transient entrainment is defined when both a sudden shortening in conduction interval to and a distinct change in electrogram morphology at a bipolar recording site are demonstrated while performing overdrive pacing of a reentrant tachycardia from a single pacing site at two different constant rates. The purpose of this article was to test the hypothesis that if an intracardiac recording site showing both orthodromic and antidromic capture with entrainment pacing is located suitably distant from the circuit, sudden shortening in conduction interval to that site may occur without any significant change in the bipolar electrogram morphology (i.e., atypical form of the fourth criterion). Atrial overdrive pacing of orthodromic tachycardia was performed in 20 patients with either left anterior (12 patients) or left posterior (8 patients) accessory pathways. We investigated the effects of overdrive pacing from the proximal or distal coronary sinus, specifically effects on the electrogram interval and the electrogram morphology at the right atrial appendage. Overdrive pacing of orthodromic tachycardia from the proximal coronary sinus was performed in 10 of the 12 patients with left anterior accessory pathways; those 10 patients demonstrated the first entrainment criterion at the right atrial appendage site. Overdrive pacing of orthodromic tachycardia at still shorter cycle lengths demonstrated a sudden shortening in conduction interval to the right atrial appendage site. Despite shortening in conduction interval the morphology of the right atrial appendage electrogram was completely or almost identical to that during orthodromic tachycardia, indicating an atypical form of the fourth criterion. This criterion was not demonstrated in patients with left posterior accessory pathways. Thus, atypical fourth entrainment criterion was demonstrated during overdrive pacing of orthodromic tachycardia from the proximal coronary sinus only in patients with left anterior accessory path ways. Demonstration of atypical fourth criterion seems largely dependent on the location of the accessory pathway, the pacing, and the recording sites.     

Left Ventricular Transvenous Electrode Dislodgement After Mustard Repair for Transposition of the Great Arteries

An 11-year-old girl who underwent Mustard's operation for complete transposition of the great arteries in infancy, developed Mobitz type II second-degree AV block 81/2 years later. A transvenous, active fixation left ventricular lead was inserted and connected to a rate responsive pacemaker. Two years later the lead dislodged due to the child's growth. A new active fixation electrode was positioned in the left ventricle below the pulmonary valve, leaving an electrode loop in the ventricle. Such an approach may prevent lead dislodgement due to growth after intraatrial repair for transposition of the great arteries, but regular radiological or echocardiographic follow-up of lead position is recommended in these patients.     

Effect of electrical stimulation on gastric electrical activity,motility and emptying

Abstract The aim was to measure the effect of gastric electrical stimulation on the frequency of canine antral pacesetter potentials (PPs), the strength of antral contractions, and the rate of gastric emptying while fasting, after feeding and with pentagastrin stimulation. Four conscious dogs with a stimulating electrode placed 10 cm proximal to the pylorus and recording electrodes and strain gauges placed 7, 5 and 3 cm proximal to the pylorus underwent myoelectric and strain gauge recordings while fasting, after feeding (250 ml 5% dextrose labelled with polyethylene glycol), and during pentagastrin infusion (0.5 μg kg^?1 min^?1) on four separate days. On each day, electrical stimulation was done using one of four stimulation frequencies (0, 6, 30 and 1200 stimuli per minute ***[s.p.m.]). Stimulation at 6 and 30 s.p.m. increased the fasting and fed PP frequency, whereas 1200 s.p.m. stimulation did not. Feeding decreased the maximum driven frequency, and pentagastrin increased it. Neither the motility index nor the gastric emptying rate were consistently changed by stimulation at any frequency. In conclusion, canine proximal antral stimulation at 6 and 30 s.p.m. sped PP frequency during fasting and after feeding, but stimulation over a wide range of frequencies had little effect on gastric contractions and emptying.     

Do Electrode and Lead Design Differences for Permanent Cardiac Pacing Translate into Clinically Demonstrable Differences? (Comparison of Sintered Platinum and Activated Vitreous and Porous Carbon Electrodes)

A randomized prospective study was undertaken to compare the electrical performances of three permanent, endocardial, tined pacing leads with different electrode designs--sintered platinum, vitreous carbon, and porous carbon. Ninety-nine patients received one of the leads (S80 31; 423S 32; S100 36). Acute R wave amplitude and ST elevation of the native endocardial electrogram, voltage threshold, impedance, and current flow at four pulse durations (0.25-1.0 msec) were measured. Voltage thresholds were measured noninvasively at each of four pulse durations at 2 days and 1, 3, and 6 months after implantation. No significant differences were found in sensing properties, or current flow at threshold at 0.5 msec pulse duration. The 423S lead had a significantly higher impedance at threshold and both a higher impedance and lower current flow at 5 V. No significant differences in threshold voltages were found between the three leads at any pulse duration, at any of the assessed times after implantation. Six-month thresholds for the S80, 423S, and S100 leads were 1.18 +/- 0.35, 1.17 +/- 0.29, and 1.06 +/- 0.38 V respectively at 0.5 msec pulse duration. Differences between 'high performance' pacing leads need to be of a greater order of magnitude before they can be exploited to give any real clinical advantage to patients.     

A randomized trial comparing two different approaches of pacemaker selection.

AIMS: DDD-pacemakers are favoured in patients with sick-sinus-syndrome or AV-block. However, AAI-pacemakers for sick-sinus-syndrome or VDD-pacemakers for AV-block may provide similar benefit with lower costs. The aim is to show that a tailored approach (TA) with arrhythmia-specific pacemaker selection was equal to a standard approach (SA) regarding quality of life (QoL) at lower costs. METHODS AND RESULTS: The study was prospective and randomized with QoL as primary endpoint. Secondary endpoints were a combined endpoint of all-cause mortality, worsening heart failure or angina, atrial fibrillation (AF), stroke, these endpoints individually and costs. Of 198 patients (age 77 +/- 10 years, 43% female, ejection fraction 54 +/- 12%, follow-up 38 +/- 15 months), 94 were randomized to SA and 104 to TA. Thirty-two patients (34%) died in the SA group vs. 25 (24%) in the TA (P= ns). QoL showed no differences in all dimensions. The combined secondary endpoint was reached more frequently with SA (51%) compared to TA (37%, P = 0.045). There was no difference regarding all single secondary endpoints. Hardware costs were reduced by 15% (P < 0.0001). CONCLUSION: In long-term follow-up, a TA is equal to SA regarding the primary endpoint QoL and secondary endpoints as AF and mortality. Depending on the healthcare system, it may significantly reduce costs.