Is Surface ECG a Useful Surrogate for Subcutaneous ECG?

Background: Surface electrocardiograms (ECGs) have been used as surrogates for subcutaneous ECGs to optimize and evaluate subcutaneous devices, but differences between surface and subcutaneous ECGs remain poorly understood. This study evaluated the correspondence between surface and subcutaneous ECGs in Reveal^® Plus (Medtronic Inc., Minneapolis, MN, USA) patients during various maneuvers. Methods: Surface electrodes were placed over the Reveal^® electrodes of 48 subjects (23 men, age 60 ± 14.3 years, body mass index 27 ± 4.9 kg/m², implant time 45 ± 29 weeks). Surface and subcutaneous ECGs were recorded simultaneously for 30 seconds during rest, isometric myopotential noise (pushing palms together), and artifact‐inducing maneuvers (repetitive displacement of device, chest thumping on device, arm flaps, handshake, hallwalk). Results: During rest, subcutaneous and surface ECGs were highly correlated (R = 0.96), had similar R‐wave amplitude (487 ± 40 vs 507 ± 49 μV, NS), and signal‐to‐noise ratio (SNR) (13.4 ± 0.8 vs 13.5 ± 0.7, NS). During myopotential noise, subcutaneous and surface ECGs were highly correlated (R = 0.91) and had similar SNR (10.0 ± 0.6 vs 9.7 ± 0.6, NS). During artifact‐inducing maneuvers, subcutaneous and surface ECGs were less correlated (R = 0.82 displacement, 0.84 chest thumping, 0.93 arm flaps, 0.90 handshake, 0.92 hallwalk) with subcutaneous SNR significantly higher than surface (11.4 ± 0.7 vs 9.9 ± 0.7 displacement, 11.1 ± 0.6 vs 8.4 ± 0.6 chest thumping, 11.5 ± 0.4 vs 10.3 ± 0.5 arm flaps, 9.5 ± 0.4 vs 8.4 ± 0.4 handshake, 12.0 ± 0.4 vs 10.0 ± 0.4 hallwalk, P < 0.05). Conclusion: Surface ECGs are adequate surrogates for subcutaneous ECGs in situations free from motion artifacts but not in situations involving movement of the device, surface electrodes, or recording equipment. During artifact‐inducing maneuvers, subcutaneous ECGs are of higher quality and less susceptible to artifacts than surface ECGs. (PACE 2010; 33:135–145)     

High‐Density Mapping of the Sinus Node in Humans: Role of Preferential Pathways and the Effect of Remodeling

Sinus Node Mapping . Introduction: The area of the functional sinus node complex exceeds that of the anatomical sinus node; however, reasons for this discrepancy are unknown. We aimed to characterize the functional sinus node complex in health and disease with high‐density simultaneous mapping. Methods and Results: Sinus node activity was characterized in 15 reference patients after ablation for supraventricular tachycardia. A further 16 patients were studied following ablation of chronic atrial flutter to determine effects of atrial remodeling. High‐density simultaneous mapping of the sinus node complex was performed using a multi‐electrode array. In reference patients, distance from superior vena cava‐right atrial (SVC‐RA) junction to earliest activation (EA) was 4 ± 4 mm and sinus break‐out (SBO) 9 ± 6 mm. Preferential pathways of conduction were observed between EA and SBO. For patients with flutter, these distances were greater (EA: 15 ± 12 mm, P = 0.003; SBO: 23 ± 11 mm, P < 0.001). Conduction time along preferential pathways was 15 ± 5 ms for reference patients and 23 ± 8 ms for patients with flutter (P = 0.005). Following pacing, distance from SVC–RA junction to EA and SBO lengthened to 13 ± 8 mm (P = 0.006) and 16 ± 10 mm (P = 0.02), respectively, in reference patients, and 19 ± 12 mm (P = 0.045), 28 ± 9 mm (P = 0.02) in patients with flutter. This resulted in caudal shifts in EA and SBO of 10 ± 9 mm and 7 ± 8 mm in reference patients but diminished shifts in patients with flutter; 4 ± 7 mm and 4 ± 6 mm. Conclusion: The functional sinus node complex demonstrates dynamic changes in activation. There are preferential pathways of conduction from sinus node to atrial myocardium. The remodeled atria demonstrate longer conduction times along preferential pathways and a restricted functional sinus node complex. (J Cardiovasc Electrophysiol, Vol. 21, pp. 532‐539, May 2010)     

Quantitative and Qualitative Aspects of Steady State Erythropoiesis Induced in Protein-Starved Rats by Long-Term Erythropoietin Injection

Protein starvation nearly arrested erythropoiesis in rats, and the red cellmass decreased during a period of 32 days from 4.0 to 2.5 ml. Protein-starvedrats, injected daily with 1.8 units of rabbit erythropoietin, had reticulocytecounts within the normal range, and their cell mass increased during the sameperiod to 4.26 ml., as compared to 4.52 ml. in normal controls. Red cell indices,Price-Jones curve and osmotic fragility were normal on blood obtained fromerythropoietin-treated groups. Differential counts on their erythroid marrowcomposition were not significantly different from those in normal rats. It isconcluded therefore that daily injection of 1.8 units of rabbit erythropoietininduced, over a period of 32 days, a steady state erythropoiesis which, on thebasis of the parameters studied, could not be distinguished from that in normalrats. No evidence of a shortened lifespan of cells formed in response to erythropoietin was found after either random (Cr⁵¹) or cohort (Fe⁵⁹) labeling.Random labeled (Cr⁵¹) cells from untreated protein-starved rats had significantly shorter chromate survival times than cells from normal or erythropoietin-treated rats. The difference is attributed to the altered age distribution in theirred cell population.

Submitted on April 29, 1965 Accepted on August 6, 1965     

Epidemiological and Diagnostic Features of Blastocystis Infection in Symptomatic Patients in Izmir Province,Turkey

Background

The aims of this study were to identify Blastocystis subtypes (STs) in a cohort of Turkish patients with various gastrointestinal symptoms using a novel Real Time PCR method developed recently for Blastocystis detection and assess the relationship between Blastocystis STs and patient symptoms.

Methods

Totally, 617 stool samples of patients with gastrointestinal symptoms were examined with microscopy and inoculated in Jones medium. Blastocystis-positive samples were further assessed to identify coinfections with other possible pathogens, including bacteria and viruses. Diagnostic efficacies of microscopy, culture and Real-Time PCR were compared. PCR products were sequenced to identify the subtypes of Blastocystis isolates.

Results

Totally 94 (15.24%) samples were positive for Blastocystis after all methods. Among these, 83 of 94 (88.3%) samples were identified with all methods, while 11 were positive only with Real Time PCR. Diarrhea and abdominal pain were the leading symptoms in the patients. The only pathogenic agent identified in 76 of 94 (80.9%) patients was Blastocystis. Subtype 3 was the leading Blastocystis subtype (44.6%), while subtypes 6 and 7 were firstly isolated from symptomatic patients in our region.

Conclusion

Comparison of three diagnostic methods indicated Real Time PCR as the most sensitive and specific method. Blastocystis was the only pathogenic agent among symptomatic patients, with subtype 3 being predominant. Patients with subtypes 6 and 7 need further assessments concerning the zoonotic potential of Blastocystis.     

Ratio of alpha-l-antitrypsin to transferrin in gingival fluid and in blood from patients with periodontal disease

Abstract – In 30 men and 29 women the mean gingival exudate ratio alpha-l-antitrypsin (A,AT)/transferrin (Tr) was higher than the mean blood ratio for A,AT/Tr, when determined by double electroimmunoassay. It suggests that A,AT penetrates the tissues more easily than transferrin probably due to its smaller molecular size or that migration into the extracellular space occurs due to consumption by proteolytic enzymes. The gingival exudate ratio and the blood ratio for AtAT/Tr were not related to periodontal disease when considered separately. However, the difference between the exudate ratio and the corresponding blood ratio was significantly less ( P = 0.02) for individuals with periodontal disease. This suggests that the ratio difference is of importance in the destruction of tooth-supporting collagen fibers.     

In vivo effect of UV-B on lymphocyte function

Whole-body exposure of normal subjects to erythemogenic doses of UV-B radiation results in a decrease in the proportion of circulating E-rosette-forming lymphocytes, an increase in the proportion of null cells and a decreased incorporation of tritiated thymidine into DNA of lymphocytes following stimulation by phytohaemagglutinin (PHA). These alterations are dose-dependent, appear soon after exposure, reach a maximum after 8-12 h, and are reversed by 48-72 h post exposure.