Aim-To analyse the immediate response of heart rate variability (HRV) in response to orthostatic stress in unexplained syncope. Subjects-69 subjects, mean (SD) age 42 (18) years, undergoing 60°head up tilt to evaluate unexplained syncope. Methods-Based on 256 second ECG samples obtained during supine and upright phases, spectral analyses of low (LF) and high frequency (HF) bands were calculated, as well as the LF/HF power ratio, reflecting the sympathovagal balance. All variables were measured just before tilt during the last five minutes of the supine position, during the first five minutes of head up tilt, and just before the end of passive tilt. Results-Symptoms occurred in 42 subjects (vasovagal syncope in 37; psychogenic syncope in five). Resting haemodynamics and HRV indices were similar in subjects with and without syncope. Immediately after assuming the upright posture, adaptation to orthostatism diVered between the two groups in that the LF/HF power ratio decreased by 11% from supine (from 2.7 (1.5) to 2.4 (1.2)) in the positive test group, while it increased by 11.5% (from 2.8 (1.5) to 3.1 (1.7)) in the negative test group (p = 0.02). This was because subjects with a positive test did not have the same increment in LF power with tilting as those with a negative test (11% v 28%, p = 0.04), while HF power did not alter. A decreased LF/HF power ratio persisted throughout head up tilt and was the only variable found to discriminate between subjects with positive and negative test results (p = 0.005, multivariate analysis). During the first five minutes of tilt, a decreased LF/HF power ratio occurred in 33 of 37 subjects in the positive group and three of 27 in the negative group. Thus a decreased LF/HF ratio had 89% sensitivity, 89% specificity, a 92% positive predictive value, and an 86% negative predictive value. Conclusions-Through the LF/HF power ratio, spectral analysis of HRV was highly correlated with head up tilt results. Subjects developing syncope late during continued head up tilt have a decrease in LF/HF ratio immediately after assuming the upright posture, implying that although symptoms have not developed the vasovagal reaction may already have begun. This emphasises the major role of the autonomic nervous system in the genesis of vasovagal (neurally mediated) syncope. (Heart 1999;82:312-318)

Transvenous pacing has become widespread in the pediatric population, but related pacemaker lead infection in young patients has rarely been reported. To determine prevalence and optimal management of pacemaker lead infection in children and young adults, the authors reviewed their pacing database including 4476 patients who previously had pacemaker implantations from 1975 to 2001. A pacemaker was implanted in 304 patients under the age of 40. Of these patients 217 of them had congenital heart disease: 108 with structural defect, 109 without (mainly complete AV blocks). Among patients with congenital heart disease, 12 developed a pacemaker lead infection (5.5%, 6 patients with structural defect, 6 without). This incidence was significantly higher than in patients < 40 years at first implantation without congenital heart disease (2.3%) and in > 40-year-old patients(1.2%, P < 0.001). However, the number of reinterventions at the pulse generator site was higher in patients having had their first implantation before the age of 40. In patients with structural cardiac defect: two died after surgical lead extraction and one died before the scheduled lead extraction. The three remaining patients had successful surgical (n = 1) or percutaneous (n = 2) lead extractions. In patients without structural cardiac defect successful percutaneous extraction (5/6) or surgical extraction (1/6 with vegetation > 25 mm) was performed. One patient with percutaneous extraction developed chronic cor pulmonale during follow-up. One infection recurred in one patient with structural cardiac defect although complete removal of the pacing material had been performed. The prevalence of pacemaker lead infection is higher in younger patients, perhaps in part due to a higher number of procedures at the pacemaker site than in the general population of patients with a pacemaker. Patients with structural cardiac defect who underwent surgical lead removal were at high risk for death. Patients with percutaneous lead extraction may develop cor pulmonale.

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.

Femoral approach pacemaker lead extraction is described as a safe and efficacious procedure. When the lead can not be removed from its myocardial insertion, the "Needle's eye snare" has become available, and it allows a femoral approach traction associated with a countertraction. Between May 1998 and May 2000, 222 lead extraction procedures were performed in 99 patients using the femoral approach. This article reports the results of the 70 lead extractions requiring the use of the Needle's eye snare for femoral approach countertraction in 39 patients with a total of 82 leads. The indications were infection, accufix leads and lead dysfunction in 56, 1 and 6 leads, respectively. The age of the leads was 113 +/- 56 months. Sixty-one (87.2%) leads were successfully extracted, the extraction was incomplete in 3 (4.3%) cases and failed in 6 (8.5%) cases. The failures were due to leads totally excluded from the venous flow for four leads, the impossibility of advancing the 16 Fr long sheath through the right and left iliac veins for one lead and one traction induced a nontolerated ventricular arrhythmia. In these cases, an extraction by a simple upper traction had been attempted in another center several months before. The complications included two deaths and one transient ischemia of the right inferior limb. Despite the selection of a series of leads for which an extraction by a simple traction on the proximal end of the lead was impossible or unsuccessful, femoral countertraction seems to be a safe and efficacious procedure. The failure of this technique occurred in patients with damaged leads due to a previous extraction procedure performed in centers with limited experience in lead extraction.