A LIGHT AND ELECTRON MICROSCOPIC STUDY OF THE NEUROPATHY OF EQUINE IDIOPATHIC LARYNGEAL HEMIPLEGIA

A study has been made of the pathological changes in the recurrent laryngeal nerves from horses with clinical and sub-clinical idiopathic laryngeal hemiplegia. Qualitative and quantitative studies showed in clinical cases there was a progressive distal loss of large myelinated fibres in the left recurrent nerve. Regenerating clusters and onion bulbs were frequently seen in affected nerves both at proximal and distal levels. Degenerating axons were characterized by collections of organelles, and denervated bands of Bungner were common. Similar but less severe changes were seen in the left recurrent nerve of sub-clinical cases, and in both the clinical and sub-clinical cases the distal right recurrent nerve was also affected. Teased fibre studies showed evidence of chronic demyelination and remyelination. The aetiology of this chronic neuropathy remains uncertain but the possibility of nerve compression is discussed.     

Randomized Comparison of Efficacy of Cooled Tip Catheter Ablation of Atrial Flutter: Anatomic Versus Electrophysiological Complete Isthmus Block

There is a subset of patients with failed ablation of the cavotricuspid isthmus (CTI) using standard catheters and with 10% of the patients having recurrences. The purpose of this study was to compare the cooled and standard ablation with regard to acute successful electrophysiological achievement of bidirectional isthmus block and the subacute anatomic characteristics of the lesions. This randomized, experimental study compares the effects of ablation on the isthmus using a cooled catheter with those of a standard ablation catheter in 16 pigs. In 12 animals, CTI block was achieved after ablation (8/8 cooled and 4/8 standard). In two animals, it was not possible to achieve complete isthmus block and two had persistent slow conduction (all four using the standard catheter). After 1 week, the animals were slaughtered. The size of the lesion was greater with the irrigated tip catheters. Transmural lesions were found in 14 animals. A complete line of anatomic isthmus block was not documented after thefirst line in six animals, four with the standard and two with the cooled catheter. A conduction block was never present across gaps > or = 5 mm. In conclusion cooled catheters achieved a complete line of electrophysiological and anatomical block in a significantly higher percentage than the standard catheters.     

Glycan composition of follicle (Sertoli) cells of the amphibian Pleurodeles waltl. A lectin histochemical study

The glycan composition of the N- and O-linked oligosaccharides of the follicle (Sertoli) cells of the urodele amphibian Pleurodeles waltl testis were identified by lectin histochemistry, performed alone or in combination with enzymatic and chemical deglycosylation methods. The follicle cells were shown to contain: (1) Fuc, Galβ(1,4)GlcNAc, GalNAc and Neu5Acα(2,3)Galβ(1,4)GlcNAc in both N- and O-linked oligosaccharides; (2) Man in N-linked glycans; and (3) Galβ(1,3)GalNAc in O-linked sugar chains. The follicle cells at the pre- and postmeiotic stages showed some differences in the UEA-I-positive Fuc characterisation, suggesting differences in the glycan composition. In addition, the sequence Neu5Acα(2,6)Gal/GalNAc was shown in the follicle cells only after spermiation, in the sperm-empty lobules of the developing glandular tissue. These results suggest that the follicle cells modify their glycoprotein content, probably for the performance of new roles, as the spermatogenetic cells develop. Thus the follicle cells surrounding male germ cells at different spermatogenetic stages would contain different glycoproteins involved in specific roles during male germ cell proliferation and maturation.     

Dysfunction of Implantable Defibrillators Caused by Slot Machines

The electrogram storage is a feature offered by the last generation of defibrillators, which enables the physician to establish whether the sensed episode and the electrical therapy delivered by the device was appropriate. The incidence of electromagnetic interferences may be higher than initially suspected with the latest generation of defibrillators. Such interference was documented in 4 out of 100 patients over a 24-month period. The electrical interference occurred in all four of them, while they were playing with slot machines. In the RR interval history, irregular QRS sensing of variable frequency was documented in some episodes. The intervals were irregular and nonphysiological, satisfying the rate cut-off criteria in an intermittent and nonsustained way. There maybe high risk of electromagnetic interference between slot machines and defibrillators. Our experience calls for a warning to all defibrillator patients and, perhaps some regulatory intervention.     

Heart rate variability and inappropriate sinus tachycardia after catheter ablation of supraventricular tachycardia

Sinus tachycardia has been reported after radiofrequency catheterablation of supraventricular tachycardia. Frequently, thesepatients require beta-blocking agents for symptomatic control. The purpose of this study was to evaluate prospectively theincidence of inappropriate sinus tachycardia and heart ratevariability after ablation of atrioventricular nodal reentranttachycardia and accessory pathways. Patients undergoing ablationhad 24-h ambulatory monitoring ECG (Holter) performed beforethe procedure, on the day of the ablation, and 3 months afterwards.There were 170 patients, mean age 48 ±23 years; 93 werefemale. A complete study of the 24-h Holter with analysis ofheart rate variability: SD, rMSSD, pNN50, high and low frequencywas obtained. There was a low prevalence of inappropriate sinus tachycardiaafter the ablation procedure (10 of 170 patients: five withfour atrioventricular nodal reentry, with posteroseptal accessorypathways and one of the latter following ablation of the leftaccessory pathway). There was no modification of time and frequencydomain parameters of heart rate variability in the remainingpatients who underwent radiofrequency ablation. Holter monitoring3 months after ablation showed that parameters of heart rateand heart rate variability had normalized in patients who haddeveloped inappropriate sinus tachycardia. Inappropriate sinus tachycardia may be initiated by both radiofrequencyablation of atrioventricular nodal reentrant tachycardia andradiofrequency ablation of posteroseptal accessory pathways.Specific damage to the posteroseptal region is responsible forthese changes, which usually recover spontaneously after 3 months.