Effects of Propafenone on Induction and Maintenance of Atrioventricular Nodal Reentrant Tachycardia

Electrophysiologic studies were performed in 10 patients with atrioventricular (A-V) nodal reentrant paroxysmal supraventricular tachycardias (PSVT), before and after intravenous administration of propafenone (1.5 mg/kg). All patients utilized an A-V nodal slow pathway for anterograde conduction and an A-V nodal fast pathway for retrograde conduction of the reentrant impulse. Propafenone depressed retrograde fast pathway conduction which was manifested by: 1) complete V-A block at all ventricular paced cycle lengths after propafenone in 3 cases; 2) increase in mean +/- SD of ventricular paced cycle length producing V-A block from less than 308 +/- 37 ms to 432 +/- 63 ms in the remaining 7 patients. Nine of the 10 patients had induction of sustained PSVT before propafenone. In 7 of the 9, PSVT could not be induced or sustained after propafenone, reflecting depression of the retrograde fast pathway conduction with either absence of atrial echoes (5 patients) or induction of nonsustained PSVT, with termination occurring after the QRS (2 patients). In 1 patient, single atrial echoes were induced before propafenone but none were noted after the drug. In only 2 patients was a sustained PSVT inducible after propafenone. In conclusion, propafenone inhibited induction of sustained A-V nodal reentrant PSVT in most patients, reflecting depression of retrograde A-V nodal fast pathway conduction.     

The normal trichogram of pubic hair

The parameters of the trichogram of the pubic hair were studied with a previously described technique. Measurements were made on males and on non-pregnant, pregnant and post-partum females. In males and non-pregnant females density and rate of growth steadily decrease with age. There was a higher percentage of telogens in women. Hair thickness was not modified. The most important findings are related to pregnancy and post-partum which did not induce any change in the parameters of the trichogram of the pubic area. These findings indicate a behaviour of the pubic hair different from the scalp and axillary hair.     

Influence of Filtering Techniques on the Time-Domain Analysis of Signal-Averaged P Wave Electrocardiogram

Differences in P Wave Filtering Techniques. introduction : The advent of signal-averaged ECG (SAECG) systems for P wave analysis has made it important to determine if the use of different filtering techniques in these systems is diagnostically equivalent.
Methods and Results : Three different high-pass filtering techniques and two cutoff frequency values were used: 29- and 40-Hz Butterworth bidirectional filter (BB29, BB40), 29-and 40-Hz Butterworth unidirectional filter (UB29, UB40), and 29- and 40-Hz least mean square filter (LIV1S29, LMS40). Normal healthy volunteers (n = 36) and patients with documented paroxysmal atrial fibrillation (n = 23) were analyzed. A custom-built SAECG system and standard bipolar orthogonal leads were used. Noise was reduced to < 0.3 μV. P wave total duration, root mean square voltage of the terminal 20, 30, and 40 msec of the filtered vector magnitude, and the area under the curve between the onset and offset of averaged unfiltered and filtered P wave vector magnitude were analyzed. Only the duration of the P wave showed statistically significant differences between groups, being longer in the PAF group for all filters and cutoff frequencies studied. A bias increment of -20 msec was detected in unidirectional and least mean square filters as compared to the bidirectional filter. Sensitivity, specificity, and predictive accuracy were > 70% for all filters; the BB40 filter yielded the best performance.
Conclusion : The normality limits derived from one filter cannot be applied directly to recordings obtained from the other filters. Critical limits must be established individually for different software settings.     

Gm and Km alleles in two Spanish Pyrenean populations (Andorra and Pallars Sobirà): a review of Gm variation in the Western Mediterranean basin

Two Spanish eastern Pyrenean populations, Andorra and Pallars Sobirà, have been tested for G1m(1,2,3,17), G2m(23), G3m(5,6,10,11,13,14,15,16,21,24,28) and Km(1) immunoglobulin allotypes. Km allele and Gm haplotype frequencies in both samples fit well into the Western Mediterranean and, more strictly, Pyrenean ranges with some peculiarities: Andorra showed an elevated frequency (14.7%) of the typical Asian and European Gm21,28;1,2,17;.. haplotype, while Pallars Sobirà was characterized by high values (3.7%) of Gm5 * ;1,17;.., a typical sub-Saharan Gm haplotype. Gm diversity assessed through genetic distance and variance analyses revealed a significant geographic partition (4.3%) of Mediterraneans among south, north-east, and north-west groups. It is interesting to note the relatively low genetic variance (2.1%) found between south and north-western Mediterraneans that could reflect ancient population relationships. More locally, genetic boundaries and diversity analyses failed to indicate any geographic pattern and/or genetic differentiation related with the political border in the Pyrenees. The present pattern of variation in this area is probably the result of genetic isolation processes, in addition to some specific demographic phenomena, in the Pyrenean valleys.     

Inhibitory Effects of N-acetylcysteine on Superoxide Anion Generation in Human Polymorphonuclear Leukocytes

It has been suggested that reactive oxygen species released by activated polymorphonuclear leukocytes (PMN) in man is one mechanism of tissue injury. Therapeutic action aimed at increasing antioxidant defence mechanisms is still a clinical challenge. This study examines the activity of N-acetylcysteine, a known antioxidant, in the protection of PMN exposed in-vitro to the chemoattractant peptide fMet-Leu-Phe (FMLP), the protein kinase C activator phorbol myristate acetate or the lipid peroxidation promoter t-butyl hydroperoxide. FMLP (3–300 nm) and phorbol myristate acetate (160 pm–160 nm) induced concentration-related superoxide anion generation. Pre-treatment with N-acetylcysteine (33–333 μm) resulted in concentration-related inhibition of superoxide production induced by FMLP (30 nm) or phorbol myristate acetate (16 nm); –log IC50 values were 3.97 ± 0.07 and 3–91 ± 0.10, respectively. Changes in intracellular calcium ion concentration ([Ca²⁺]_i) induced by FMLP (30 nm) were studied in fura-2-loaded human PMN. FMLP produced a transient calcium response, i.e. a peak followed by decay to a residual value above baseline. N-Acetylcysteine (333 μm) did not affect either basal [Ca²⁺]_i values or changes in [Ca²⁺]_i values after treatment with FMLP. Activation by phorbol myristate acetate caused a reduction in glutathione levels from 5.94 ± 0.86 (control) to 1.84 ± 0.51 nmol/3 × 10⁶ cells (P < 0.05 compared with control). Pre-treatment with N-acetylcysteine (333 μm) fully reversed the reduction in glutathione levels induced by phorbol myristate acetate (4.83 ± 0.68 nmol/3 × 10⁶ cells; P > 0.05 compared with control). Exposure to t-butyl hydroperoxide (0.5 mm, 30 min) markedly increased malondialdehyde levels (from 0.03 ± 0.02 to 0.73 ± 0.07 nmol/10⁶ cells), and index of lipid peroxidation. Malondialdehyde levels were significantly reduced in PMN treated with N-acetylcysteine (333 μm; 0.55 ± 0.04 nmol/10⁶ cells; P < 0.05 compared with untreated cells exposed to t-butyl hydroperoxide). In conclusion, N-acetylcysteine reduces superoxide generation in response to FMLP and phorbol myristate acetate and partially protects against lipid peroxidation in PMN from man. The protection afforded by N-acetylcysteine is not related to alteration of the intracellular calcium signal but might be effected by replenishment of the intracellular glutathione levels.     

Rolipram inhibits airway microvascular leakage induced by platelet-activating factor,histamine and bradykinin in guinea-pigs

Abstract— Rolipram (0·1–1000 μg kg^?1, i.v.) reduced the increase in microvascular permeability induced by platelet-activating factor (PAF; 50 ng kg^?1, i.v.) at different sites of the guinea-pig airways. Rolipram (1–100μg kg^?1, i.v.) inhibited histamine (30μg kg^?1, i.v.)-and bradykinin (0·3 μg kg, i.v.)-induced airway microvascular leakage. These effects of rolipram were obtained at doses which inhibit histamine (7–20 μg kg^?1 min^?1)-induced bronchoconstriction (IC50 = 3 ± 1 μg kg, i.v.) without depressing arterial blood pressure in the guinea-pig. Aminophylline (50 mg kg^?1) did not change the effect of PAF. The anti-exudative effect of rolipram is of potential therapeutic value in asthma.     

Incidence and Significance of Early Recurrences Associated with Different Ablation Strategies for AF: A STAR‐AF Substudy

Early Recurrence in STAR‐AF. Background: Early recurrences of atrial tachyarrhythmias (ERAT) are common after atrial fibrillation (AF) ablation, and predict late recurrences (LR). We sought to determine the impact of different ablation strategies on ERAT and LR. Methods and Results: The STAR‐AF trial randomized 100  patients with paroxysmal or persistent AF to ablation of complex fractionated electrograms (CFAE) alone, pulmonary vein isolation (PVI) alone, or combined PVI + CFAE. Patients were followed for 12  months. ERAT was defined as any recurrence of AF, atrial tachycardia, or flutter (AT/AFL) >30 seconds during the first 3  months of follow‐up. LR was defined as any recurrence of AF/AT/AFL >30 seconds 3–12  months post. Forty‐nine patients experienced ERAT. The index ablation strategy was the only independent predictor of ERAT on multivariate analysis (HR 2.24 PVI vs PVI + CFAE; and HR 2.65 CFAE vs PVI + CFAE). Fifty‐two patients experienced LR. The presence of ERAT (HR 3.23), the use of antiarrhythmic drug (AAD) in the first 3  months postablation (HR 2.85), and the index ablation strategy were independently associated with LR (HR 3.42 PVI vs PVI + CFAE; HR 4.72 CFAE vs PVI + CFAE). Thirty‐five of 49 (71%) patients with ERAT and 17 (33%) of 51  patients without ERAT had LR (P  < 0.0001). Among patients with ERAT, increased left atrium size (HR 1.08), the use of AAD in the first 3  months postablation (HR 2.86) and the index ablation strategy were independently associated with LR (HR 4.77 PVI vs PVI + CFAE; HR 4.45 CFAE vs PVI + CFAE). Conclusion: ERAT is common following AF ablation and is strongly associated with LR. Although CFAE ablation alone results in higher rates of early and LR, the addition of CFAE to PVI results in increased long‐term success without an increase in ERAT. (J Cardiovasc Electrophysiol, Vol. 23, pp. 1295‐1301, December 2012)     

Acute Effects of Radiofrequency Ablation upon Atrial Conduction in Proximity to the Lesion Site

The electrophysiological effects of RF ablation upon the areas in proximity to the lesioned zones have not yet been well characterized. An experimental model is used to investigate atrial conduction in the boundaries of RF damaged zones. In 11 isolated and perfused rabbit hearts, endocardial atrial electrograms were recorded using an 80-Iead multiple electrode positioned in the left atrium. Both before and after the RF application (5 W, 8 s, 1-mm diameter unipolar epicardial electrode) in the mid-portion of the free left atrial wall, measurements were made of conduction time from the pacing zone (posterior wall of the left atrium) to three points between 7.5 and 7.9 mm distal to the damaged zone. Conduction velocity and the direction of the activation propagation vector were determined in ten groups of four electrodes positioned around the damaged zone, and at the left atrial appendage. The mean diameter (± SEM) of the transmural lesions produced by RF ablation and defined by macroscopic examination was 4.2 ± 0.2 mm. The conduction times to the three points distal to the lesion site were significantly prolonged as a result of RF ablation: 7.6 ± 0.4, 7.4 ± 0.5, and 6.9 ± 1.0 ms (control); and 11.3 ± 1.0 (P ≤ 0.01), 11.1 ± 1.3 (P < 0.01), 10.6 ± 1.4 ms (P < 0.05) (post-RF). The differences between the conduction velocities determined in the areas surrounding the lesion, before and after RF application, failed to reach statistical significance: 86.2 ± 6.5 cm/s (control) versus 75.5 ± 5.7 cm/s (post-RF) (NS). After RF, significant variations were only observed in the direction of impulse propagation in the proximal-inferior quadrant adjacent to the lesion site, the difference being -61°± 18° (P < 0.02). In 2 of 4 experiments in which the lesion size was increased by a second RF application (5 W, 16 s), tachycardias with activation sequence around the lesion could be induced, with cycle lengths of 56 and 50 ms, respectively. In the atrial wall, the conduction times to the regions distal to the RF lesion are significantly prolonged. No significant changes are observed in conduction velocity in the areas in proximity to the lesion. Prolonged conduction to the areas distal to the ablation site is due to the lengthened pathway traveled by the impulses in reaching these areas. Tachycardias with activation patterns that suggest reentry around the RF damaged zone may be induced.     

Transvenous Ablation with High Frequency Energy for Atrioventricular Junctional (AV Nodal) Reentrant Tachycardia

We performed transcatheter AV junction ablation with high frequency energy in four patients with AV nodal reentrant tachycardia where extensive trials of several antiarrhythmic drugs failed to prevent further recurrences of tachycardia. Initially high frequency catheter ablation induced complete AV block in all patients. A recuperation of AV 1:1 conduction followed some time later, persisting in follow-up. No complications have been encountered in either the acute phase or the follow-up (from 6 to 8 months; mean +/- SD: 8.7 +/- 2.5 months). The electrophysiological study was carried out 6 weeks following ablation, and all patients showed AV 1:1 conduction. No dual nodal pathway was encountered and no tachycardia could be triggered. With refinement of the method, the potential application of high frequency energy to interrupt intranodal or perinodal connections responsible for reentrant supraventricular tachycardia or to retard AV nodal conduction appears promising.