Spinal cord stimulation and 30-minute heart rate variability in refractory angina patients.

BACKGROUND: Spinal cord stimulation (SCS) has proven antianginal and antiischemic effects in severe coronary artery disease patients, minimizing frequency, intensity, and duration of pain. The mechanism explaining these effects has been detected in a sympathicolytic effect of the SCS. We monitored 30-minute-long recordings of the heart rate variability (HRV) and its spectral power parameters to evaluate the influence of SCS on the sympathetic/parasympathetic balance. METHODS AND RESULTS: Eight patients underwent HRV recordings in controlled environmental conditions. The patients were seated in a relaxed position and isolated from external contacts. During three consecutive 30-minute periods, the SCS was programmed, in a randomized fashion, to stimulate at a level generating paresthesias (ON), at a subliminal level (SUB, amplitude 80% of ON), or switched off (OFF). The low-frequency/high-frequency ratio during stimulation (ON) was significantly lower compared to that found while the SCS was turned OFF (0.54, 0.35-1.04 vs 1.21, 0.80-2.48; P = 0.036). The stimulation resulted in a median 52% (33-65%) reduction of the sympathetic activity compared to basal (ON vs OFF, P = 0.049). CONCLUSION: No difference emerged instead comparing OFF versus SUB (P = 0.575). The stimulation effect was not influenced by the randomized sequence. Thirty-minute SCS significantly influenced the sympathetic/parasympathetic balance reducing sympathetic modulation.

Accuracy of swabs, tissue specimens, and lead samples in diagnosis of cardiac rhythm management device infections.

AIMS: Pacemaker and implantable-cardioverter defibrillator lead infections widely increased with consequent need to accurately recognize responsible bacteria. METHODS: Between May 2003 and December 2007, we extracted 118 leads, 104 (87.3%) due to infections (sepsis, lead-associated endocarditis, pocket infection) or chronic draining sinus (with negative local bacteriological analyses). Swabs and tissue specimens from pocket and fragments of pin and tip of each extracted lead were obtained during extraction and sent for bacteriological examination. RESULTS: Cultures from explanted lead pins returned positive results in 100% of the cases presenting with local infections and in 92.5% of those with chronic draining sinus. In cases of sepsis, positive results of blood samples are less common than lead samples (58.3 vs 86.7, P = 0.02), the latter being more sensitive for infection diagnosis. Concordance between bacterial isolates from pocket and lead is quite low, approaching 45%, seemingly due to contamination effect. Concordance between isolates within the lead (pin and tip) is quite high, close to 70%, reflecting a more accurate expression of the real infection. In cases of sepsis, concordance between lead and blood samples, and mainly from tip and blood, is very high, resembling 80-85%; consequently bacterial isolates from the lead, particularly from lead tip, are clearly associated with clinical infections. CONCLUSIONS: Our results strongly support the hypothesis that chronic draining sinus is often sustained by infection. Moreover, diagnostic accuracy of lead samples is higher not only than swabs and tissue samples, but also than blood samples to confirm an infection and to guide effective therapy.

Meta-analysis appraising high clopidogrel loading in patients undergoing percutaneous coronary intervention.

Combined antiplatelet treatment with aspirin and clopidogrel is pivotal to minimize periprocedural adverse events in patients who undergo percutaneous coronary intervention. However, there is debate on the best clopidogrel loading dose. The investigators performed a systematic review and meta-analysis of the optimal clopidogrel loading dose. Pertinent trials comparing high (>300 mg) and standard (300 mg) clopidogrel loading doses in patients scheduled for catheterization and/or percutaneous coronary intervention were systematically searched in BioMedCentral, CENTRAL, Google Scholar, and PubMed (December 2006). The primary end point was the 1-month rate of death or myocardial infarction. Secondary end points included other ischemic and bleeding adverse effects. Peto odds ratios were computed. A total of 10 studies (7 randomized, 3 nonrandomized) were included, enrolling 1,567 patients (712 loaded with 300 mg, 11 with 450 mg, 790 with 600 mg, and 54 with 900 mg). Overall, a high loading dose proved significantly superior to a standard loading dose in preventing cardiac death or nonfatal myocardial infarction (odds ratio 0.54, 95% confidence interval 0.32 to 0.90, p = 0.02), without any statistically significant increase in major or minor bleedings (p = 0.55 and p = 0.98, respectively). Sensitivity analysis restricted to randomized trials confirmed the superiority of a high loading dose regimen (p = 0.0031). Meta-regression disclosed a significant interaction between event rate and the benefits of high loading doses (p = 0.005), suggesting that the greater the underlying risk, the greater the favorable impact of a high loading dose. In conclusion, a high clopidogrel loading dose (>300 mg) significantly reduces early ischemic events in patients scheduled for percutaneous coronary intervention.