Relationship between duration of repolarisation and T wave amplitude in patients with positive or negative T wave alternans

BACKGROUND: Experimental studies documented the relationship between T wave alternans (TWA) and duration of refractoriness. To date, association between TWA and QT interval on standard ECG has not been examined. Aim. To assess the relationship between TWA and QT interval. METHODS: The study group consisted of 70 patients (57 males, mean age 56+/-16 years) with implantable cardioverterdefibrillator (ICD). TWA was measured using a high-resolution ECG obtained from surface orthogonal bipolar XYZ leads and analysed using a Fast Fourier transform. All recordings were performed during ventricular pacing at 100 betas/min. Correlation between T wave amplitude (T max) and QT interval (measured from R wave to T max) was calculated. RESULTS: TWA was found in 18 patients. In this group of patients, there was a significant positive correlation between Tmax and QT (r = 0.766), whereas in patients with negative TWA no such correlation was detected. CONCLUSIONS: (1) Positive correlation between QT and T max probably depicts the relationship between T wave amplitude and duration of repolarisation, which is associated with TWA; (2) methods used for T wave localisation, based on the identification of Q wave (with possible QT-RR correction) overestimate TWA due to periodic changes (with TWA frequency) in location of T wave in the analysed window; and (3) these results provide new insights in the genesis of TWA.     

Implantation of an automatic cardioverter-defibrillator in small children--two case reports

Implantation of an automatic cardioverter-defibrillator (ICD) in children may be challenging due to the increased risk of periprocedural and long-term complications. ICD was implanted in two boys with hypertrophic cardiomyopathy, aged 6 and 9 years, with of a body weight of 20 and 25 kg, respectively. In one patient an ICD was implanted due to a history of ventricular fibrillation whereas the second patient underwent prophylactic ICD implantation due to a family history of sudden cardiac death. No short- or mid-term complications were recorded. Difficulties and risks of ICD implantation in children are discussed.     

Proteolytic Enzymes Activities in Patients After Myocardial Infarction Correlate with Serum Concentration of TGF-β

Myocardial infarction (MI) is caused by occlusion of coronary artery and insufficient oxygen supply to a certain area of myocardium. Its necrosis appears as a result of MI. The process of tissue repair after MI is very complicated and it is influenced by numerous factors, including growth factors and proteolytic enzymes. The aim of the study was to determine serum transforming growth factor β (TGF-β) concentration on day 2 and 7 after MI and to asses the relationship of this growth factor with serum proteolytic activity of collagenase and elastase. In addition, the effect of fibrynolytic treatment on these factors was evaluated. About 100 patients with MI were enrolled to the study. The control group consisted of 50 healthy individuals. We observed that TGF-β1 concentration correlated positively with collagenase activity on the second day after MI and that it also correlated positively with elastase activity on day 2 and 7 after MI. Moreover, treatment with streptokinase (SK) caused a significant increase of TGF-β serum concentration. Our data indicate that TGF-β1 may be one of the factors involved in tissue repair process after MI. Its effect seems to be mediated by collagenase and elastase and may change with the time that elapsed after MI.     

Untersuchungen von polymeren im massenspektrometer, 4. Abbaureaktionen von polybenzylen

The degradation reactions of unsubstituted poly(1,4-phenylenemethylene)s ( A ) (polybenzyls), poly[(2,5-dimethyl-l,4-phenylene)methylene] [poly(2,5-dimethylbenzyl)] ( B ), poly[(2,3,5,6-tetramethyl- 1,4-phenylene)methylene] [poly(2,3,5,6-tetramethylbenzyl)] ( C ), and poly( 1,4-phenylenethylene) [poly(a-methylbenzyl)] (D) were investigated by direct pyrolysis in the mass spectrometer. Mass pyrograms of polybenzyls made under different reaction conditions were compared in order to obtain direct informations on structural differences, such as branching and different linkages of the benzyl units; degradation products indicating a branched polymer could be found in one example. The thermal degradation of the unsubstituted polybenzyls and the poly(2,5-dimethylbenzyl) occurs mainly by disproportionation and transfer of hydrogen from the CH₂-groups, yielding monomeric and oligomeric degradation products with saturated (phenyl-, alkyl-) and unsaturated (quinonemethid-) endgroups; whereas on the degradation of poly(α-methyl-benzyl) pyrolytic products with vinyl endgroups were also found. The degradation behaviour of poly(2,3,5,6-tetramethylbenzyl) was found, however, to be greatly different, caused by the steric hindrance of the substituents at the phenyl groups. Besides a lower thermostability we found the mass spectral pattern indicating a different mechanism of thermal degradation. “a-benzyl-”, “β-benzyl”-, and “alkyl-cleavage”, as well as ortho-rearrangement were found as the main fragmentations of the ionized pyrolytic products.     

The occurrence of phase-4 block in the anomalous bundle of patients with Wolff-Parkinson-White syndrome.

Conduction in the Kent bundle was studied in 17 patients with WPW syndrome, before and after administration of ajmaline and amiodarone. Before drug administration, only one patient showed phase-3 block and only one other showed phase-4 block. After administration of ajmaline to 11 patients and amiodarone to 16 patients (each patient received at least one of the drugs and the two drugs were given independently to 10 patients), the occurrence of phase-3 block alone in the Kent bundle was documented in 9 patients of the 17, phase-4 block alone in 1, and phase-3 and phase-4 block together with a typical accodion in 3. In 4 patients conduction in the Kent bundle was not modified. The phase-3 and phase-4 block as well as the accordion effect in the Kent bundle were similar to the same phenomena previously described in patients with diseased or in dogs with injured intraventricular conducting fascicles. The fact that the Kent bundle can show the same physiological and pharmacological behavior as a diseased His bundle or bundle branches is highly significant, first, because it may indicate that the anomalous bundle is also composed of Purkinje or Purkinje-like fibers and, secondly, because it may help to distinguish a normal from a diseased Kent bundle, and this may become essential for determining the prognosis and treatment of patients with WPW syndrome. The Kent bundle can be compared with a normal or diseased extra-His bundle.     

Effect of roasting on the allergenicity of major peanut allergens Ara h 1 and Ara h 2/6: the necessity of degranulation assays

Background Peanuts are often consumed after roasting, a process that alters the three‐dimensional structure of allergens and leads to Maillard modification. Such changes are likely to affect their allergenicity. Objective We aimed to establish the effect of thermal treatment mimicking the roasting process on the allergenicity of Ara h 1 and a mix of 2S albumins from peanut (Ara h 2/6). Methods Ara h 1 and Ara h 2/6 were purified from raw peanuts and heated in a dry form for 20 min at 145 °C in the presence (R+g) or absence (R?g) of glucose, and soluble proteins were then extracted. Sera obtained from 12 well‐characterized peanut‐allergic patients were used to assess the IgE binding and degranulation capacities of the allergens. Results Extensive heating at low moisture resulted in the hydrolysis of both Ara h 1 and Ara h 2/6. However, in contrast to Ara h 2/6, soluble R+g Ara h 1 formed large aggregates. Although the IgE‐binding capacity of R+g and R?g Ara h 1 was decreased 9000‐ and 3.6‐fold, respectively, compared with native Ara h 1, their capacity to elicit mediator release was increased. Conversely, both the IgE‐binding capacity and the degranulation capacity of R?g Ara h 2/6 were 600–700‐fold lower compared with the native form, although the presence of glucose during heating significantly moderated these losses. Conclusions and Clinical Relevance Extensive heating reduced the degranulation capacity of Ara h 2/6 but significantly increased the degranulation capacity of Ara h 1. This observation can have important ramifications for component‐resolved approaches for diagnosis and demonstrates the importance of investigating the degranulation capacity in addition to IgE reactivity when assessing the effects of food processing on the allergenicity of proteins. Cite this as: Y. M. Vissers, M. Iwan, K. Adel‐Patient, P. Stahl Skov, N. M. Rigby, P. E. Johnson, P. Mandrup Müller, L. Przybylski‐Nicaise, M. Schaap, J. Ruinemans‐Koerts, A. P. H. Jansen, E. N. C. Mills, H. F. J. Savelkoul and H. J. Wichers, Clinical & Experimental Allergy, 2011 (41) 1631–1642.     

Usefulness of the ajmaline test in patients with latent bundle branch block

Twelve patients were studied with intermittent bundle branch block whose conduction disturbance disappeared completely and could no longer be recorded even after provoked changes in heart rate. Premature atrial stimulation and atrial pacing at rapid rates were performed in nine patients; in none of these nine were these procedures able to evoke the complete bundle branch block pattern that all patients exhibited before the spontaneous normalization of conduction. In marked contrast, the administration of ajmaline (1 mg/kg body weight, intravenously in 90 seconds) caused the bundle branch block pattern to reappear in 10 (83.3 percent) of the 12 patients 30 to 120 seconds after the end of the injection, and in 11 patients (91.6 percent) when additional atrial stimulation was performed in 1 of the 2 “failures.” This pharmacologie test was much more rapid and simple than electrophysiologic testing and it was noninvasive. Results of this study suggest that some form of subclinical fascicular injury was present (or had persisted) at a time when intraventricular conduction was persistently normal even though no significant physiologic alteration could be demonstrated by the atrial stimulation techniques. The ajmaline test may become a valuable tool for uncovering cases of latent bundle branch block and furthering our knowledge of the early natural history of intraventricular block.