[Subclavian vein puncture as a primary approach for pacemaker lead implantation]. / Punktion der Vena subclavia als primärer Zugang bei der Schrittmacher-Sondenimplantation.

In the beginning of transvenous pacemaker therapy, the external or alternatively internal jugular vein was commonly used for lead implantation. Due to frequent long-term complications both approaches are nowadays obsolete. In most pacemaker centers implantation via the cephalic vein has become standard. As an alternative, in 1975 Sterz et al. introduced puncture of the subclavian vein in the Seldinger technique as an approach for lead implantation. At this time, the commonly used introducers of pacemaker leads had to be cut for removal. No earlier than 1980 "peel away" introducers were commercially available. Since then, we consequently use this technique for implantation of single or dual chamber pacemaker devices. In the course of the last seven years merely 1.5-2% of implantations were performed via the cephalic vein; no jugular vein approach was performed. Due to a routinely performed subclavian vein puncture, we were able to optimize the procedure, proven by an enormous reduction in implantation time (local anesthesia - skin closure), x-ray time and complication rate. In the year 2000 we performed 52 implantations of a single chamber device with an average fluoroscopy time of 1.5 (0.3-9.3) minutes, radiation dose of 4.5 (0.1-47) Gycm(2) and implantation time of 17.6 (8-40) minutes and 144 implantations of a dual chamber device with an average fluoroscopy time of 2.86 (0.7-6.6) minutes, radiation dose of 8.31 (0.7-28) Gycm(2) and implantation time of 21.25 (10-45) minutes. Complications were rare, clinically irrelevant arterial punctures. Neither nerval damage nor pneumothoraces with the necessity for chest tube placement were seen in the above mentioned time frame. No early or late thrombosis of the subclavian vein was encountered. The primary subclavian vein approach led to an enormous reduction in overall procedure time without significant morbidity.

[A simple method for AV-delay determination in dual chamber pacemakers]. / Eine einfache Methode zur Bestimmung des AV-Intervalls bei Zweikammerschrittmachern.

The individual adjustment of the AV intervals is a prerequisite for the hemodynamic advantages of dual-chamber pacing. The methods for the optimization of the AV-Delay (AVD) applied so far are time intensive. A simple and fast method is the approximate adjustment of the AVD with the surface-ECG. The aim of this work is the conception and validation of this new method. The optimal AVD is given if at the end of the atrial contraction the mitral valve is closed by the ventricular increase of pressure. In order to achieve this with pacemaker patients, the individually different atrial and ventricular conduction times must be considered. The different conduction times can be determined from the surface-ECG. Intra- and interatrial conduction times can be defined by the beginning of the atrial spike up to the end of the p-wave. The beginning of ventricular pressure increase corresponds to the peak of the stimulated QRS complex (beginning of the Iso-Volumetric Contraction time, ISVC) and depends on the interventricular conduction time.¶ In the case of 100 patients, who did not receive a cardiac pacemaker, the interval at the end of the p-wave (left atrial excitation, EP) up to the peak of the r-wave (ISVC) during rest and exercise was measured and an age referred average value of 100ms determined; this serves as standard value if no AV-conduction is available. The approximated optimized AVD is given if the interval of the end at the p-wave to the peak of the QRS-Complex amounts to 100ms. By means of a simple algorithm, the optimized AVD can, thus, be calculated:¶ After programming a long AVD, the interval at the end of the native or paced p-wave up to the peak of the stimulated QRS-Complex (EP/ISVC) is determined. This value EP/ISVC is then taken from the long AVD, the 100ms standard value is added and one receives the approximately optimized AVD.¶ In order to validate the described method, 13 consecutive patients (2 female, 11 male, average age 67±7.8 years) were included, and received for different indication (7 sick sinus syndrome, 4 AV block III, 2 binode disease) a DDD pacemaker (Affinity, St. Jude Medical).¶ About 8 weeks after implantation all patients underwent a PA catheter investigation, in order to optimize the AV-/PV-Delay of the pacemaker regarding the maximum cardiac output (CO). For CO measurement the thermo dilution method was applied. Altogether 17 complete hemodynamic measurements (9 times with different PVDs, 8 times with different AVDs) were executed. The patients 10-13 could be examined both in the VDD and in the DDD mode.¶ The minimum determined CO amounted to 3.5 l/min, the maximal CO 7.1 l/min and the average value was 5.62±0.98 l/min. In all patients not only one optimal AVD was found but, moreover, a varied interval of AVDs with which optimal CO results could be obtained. The comparison of surface ECG optimized AVD with the PA catheter optimized AVD showed a statistically significant correlation (0.825PV, 0.982 AV, P<0.01). Sixteen out of seventeen measurements were at an interval which enables hemodynamic optimal CO or stroke volume. Only one AVD determined from the surface ECG was situated slightly (10 ms) outside of a hemodynamic optimal determined AVD. Despite the encouraging test results represented here, further studies should examine the value of the new algorithm in comparison with the other techniques for AVD optimization.

Determinants of dual chamber pulse generators longevity.

The aim of this study was to investigate the effect of battery capacity, internal current drain, and stimulation energy on pulse generators longevity, and if battery impedance measurements can reliably predict pulse generators end-of-life. For this purpose, the records of 577 patients with a mean age of 65 +/- 14 years who had undergone implantation of two different dual chamber pulse generators (PG1: 409; PG2: 168) were retrospectively reviewed. Battery capacity were 2.3 Ah (PG1) and 3.0 Ah (PG2) while current drain at comparable nominal settings was 20 microA (PG1) and 30 microA (PG2) indicating a higher internal current drain of PG2. After a mean follow-up of 46 +/- 23 months, stimulation energy at reprogrammed output settings was significantly higher in PG1 as compared to PG2 (17.1 +/- 0.14) vs 15.5 +/- 0.24 J). Three PG1 (0.7%) and 12 PG2 (7.1%) (P < 0.01) had to be exchanged after a mean of 77.3 +/- 5.3 months (PG1) and 75 +/- 13.5 months (PG2) (P = NS) due to end-of-life being reached. The difference in battery impedances of PG1 and PG2 gained statistical significance 5 years after implantation (1.0 k omega vs 2.4 +/- 6.7 k omega) preceding the significant difference in PG survival after 6 years (98.7 +/- 1.3% vs 90.7 +/- 4.8%). These results indicate that internal current drain is the most important determinant of the pulse generators longevity and that battery impedance can reliably predict end-of-life. Therefore, the essential information about internal current drain should be available for each pacemaker, since it is required for adequate pulse generator selection. Diagnostic functions of dual chamber pulse generators should include measurements of battery impedance.

[Progressive left ventricular dilatation following anterior myocardial infarct as a determinant for the development of heart failure]. / Progrediente linksventrikuläre Dilatation nach Vorderwandinfarkt als Determinante für die Entwicklung einer Herzinsuffizienz.

35 consecutive patients were studied prospectively with respect to echocardiographic left ventricular size after anterior myocardial infarction. In 25 patients sufficient follow-up was possible. Another 57 patients and volunteers were examined to prove accuracy in comparison to angiocardiography and nuclear magnetic resonance imaging and reproducibility as well as to define normal values. While two-thirds of all patients did not develop left ventricular dilation, one-third showed marked dilation with left ventricular size being 41% above mean normal value. All patients who subsequently developed congestive heart failure or died were in this group. Two-thirds showed no left ventricular dilation and had an uneventful follow-up. Mean left ventricular dilation for all infarcts was 22% within 4 weeks and 26% within 6.3 months, but some patients showed marked left ventricular dilation beyond 4 weeks. We conclude that serial echocardiography is very useful for stratification of risk for CHF after myocardial infarction, and left ventricular dilation is a major risk factor for CHF.

Implantation of programmable infusion pumps for insulin delivery in type I diabetic patients.

Five type I diabetic patients were followed prospectively during treatment with continuous subcutaneous insulin infusion by externally worn pumps and during the first 12 months after implantation of a remote-controlled insulin infusion device (ID1, Siemens AG). Stabilized insulin (Hoe 21 GH, Hoechst AG) was infused intravenously in two and intraperitoneally in three patients. Total observation time was 47.2 patient-months after implantation. Two devices had to be explanted prematurely, one because of a technical failure after 101 days, one due to a skin necrosis over the implant after 236 days. HbA1, frequency of hypoglycemia, total insulin dose, and basal rate infusion did not change after implantation. There was a reduction in the insulin antibodies 6 months after start of intravenous or intraperitoneal insulin delivery. Fasting plasma free insulin levels could be normalized only by intraperitoneal insulin infusion. Although a technical and a surgical problem was observed, our data show the successful implantation and clinical use of programmable dosing devices and stabilized insulin.

Electrolysis of unipolar pacing leads.

A 90-year-old man with bradycardia and Stokes-Adams attacks had a unipolar VVI pacemaker implanted. Twice within a short period of time we registered a total loss of function: the first incident was caused by a "fracture" between lead and electrode, and the second was due to partial dissolving of the lead. Both times a new lead electrode was implanted; the second time we replaced the pulse generator as well. Pacemaker analysis showed a capacitor defect leading to a 50 microampere anodal DC leakage that caused electrolysis of the helical coil conductors. The patient had no clinical symptoms besides those due to loss of pacemaker function. The present case report and others in the literature indicate that when an electrode lead fracture is found, it is necessary to check the pacemaker for DC leakage.

Hemodynamic response to digitalization in patients with hypertensive cardiovascular disease.

Twenty-eight patients with hypertensive cardiovascular disease (HCD) and incipient myocardial dysfunction underwent hemodynamic studies at rest and during exercise before and 30 minutes after administration of 0.6 mg beta-methyl-digoxin intravenously. Measurements were made during right heart catheterization with a balloon-tipped catheter. The hemodynamic changes after administration of digitalis did not demonstrate a consistent and uniform improvement of cardiac performance in all patients with HCD and myocardial dysfunction. When separating 11 patients with pervious myocardial infarctions or documented coronary artery disease (CAD) (= Group I) from the remaining 17 subjects without clinical and/or angiographic signs of CAD (= Group II), there were significant differences in the hemodynamic response to digitalis: In Group I, pulmonary artery wedge pressure (PAWP) after digitalis decreased only slightly and insignificantly from 8.7 to 7.4 mm Hg at rest and from 27.6 to 26.4 mm Hg during steady state exercise. Cardiac output (CO) remained essentially unchanged with a tendency to decrease after digitalis: 5.9 vs. 5.8 L/min at rest and 11.5 vs 11.1 L/min during exercise. At rest, even patients of Group II showed only minor decrease of PAWP from 8.8 to 7.2 mm Hg; during exercise these patients demonstrated marked improvement of cardiac performance with a significant decrease of PAWP after digitalis from 27.8 to 22.3 mm Hg (p less than 0.01). With one exception, there was a more or less pronounced reduction of PAWP after the drug was given. No significant change of CO after digitalis was measured in this group: 6.2 vs. 5.9 L/min at rest and 13.4 vs. 13.5 L/min during exercise. The different hemodynamic patterns of responders and non-responders to the glycoside will be discussed.