Unusual Features of Right and Left Idiopathic Ventricular Tachycardia Aholished hy Radiofrequency Catheter Ablation

Two unusual cases are presented with idiopathic right and left ventricular tachycardia(IVT) with intriguing clinical and electrophysiological characteristics. The first patient with a sustained IVT of right ventricular outflow tract origin, and an electrophysiological mechanism suggesting reentry, had been resuscitated from cardiac arrest. The second patient had an IVT with a left bundle branch block morphology, which originated from the basal-septal region of the left ventricle(left ventricular outflow tract tachycardia). Both patients were cured with radiofrequency catheter ablation, guided by endocardial activation sequence and pace mapping.     

Can P Wave Wavelet Analysis Predict Atrial Fibrillation After Coronary Artery Bypass Grafting?

VASSILIKOS V., et al. : Can P Wave Wavelet Analysis Predict Atrial Fibrillation After Coronary Artery Bypass Grafting? The purpose of this study was the evaluation of Morlet wavelet analysis of the P wave as a means of predicting the development of atrial fibrillation (AF) in patients who undergo coronary artery bypass grafting (CABG). The P wave was analyzed using the Morlet wavelet in 50 patients who underwent successful CABG. Group A consisted of 17 patients, 12 men and 5 women, of mean age   66.9 ± 5.9 years   , who developed AF postoperatively. Group B consisted of 33 patients, 29 men and 4 women, mean age   62.4 ± 7.8 years   , who remained arrhythmia-free. Using custom-designed software, P wave duration and wavelet parameters expressing the mean and maximum energy of the P wave were calculated from 3-channel digital recordings derived from orthogonal ECG leads (X, Y, and Z), and the vector magnitude (VM) was determined in each of 3 frequency bands (200–160 Hz, 150–100 Hz and 90–50 Hz). Univariate logistic-regression analysis identified a history of hypertension, the mean and maximum energies in all frequency bands along the Z axis, the mean and maximum energies (expressed by the VM) in the 200–160 Hz frequency band, and the mean energy in the 150–100 Hz frequency band along the Y axis as predictors for post-CABG AF. Multivariate analysis identified hypertension, ejection fraction, and the maximum energies in the 90–50 Hz frequency band along the Z and composite-vector axes as independent predictors. This multivariate model had a sensitivity of 91% and a specificity of 65%. We conclude that the Morlet wavelet analysis of the P wave is a very sensitive method of identifying patients who are likely to develop AF after CABG. The occurrence of post-CABG AF can be explained by a different activation pattern along the Z axis. (PACE 2003; 26[Pt. II]:305–309)     

Immunoreactivity and conformation of the P-P-G-M-R-P-P repetitive epitope of the Sm autoantigen

Anti-Sm antibodies are usually considered highly specific for systemic lupus erythematosus (SLE), while anti-UI RNP antibodies are found in high titers in patients with mixed connective tissue disease (MCTD). The sequence P¹-P-G-M-R-P-P⁷, present in three copies in the Sm (Ul-U6 RNA-protein complex) autoantigen, is an important functional domain of the antigenic determinants. The immunoreactivity of this proline-rich repetitive epitope was investigated by testing sera with various autoantibody specificities for reactivity against this epitope, as well as its conformational properties by means of ID and 2D ¹HNMR spectroscopy. It was found that the P-P-G-M-R-P-P epitope is recognized mainly by anti-UlRNP and/or anti-Sm positive sera, but also by anti-Ro(SSA) (hY1RNA-protein complex) and anti-La(SSB) (hY1RNA-protein complex) positive sera, although these sera are negative for anti-UlRNP and anti-Sm. Conformational analysis of the proline-rich epitope in DMSO-d₆ solution obtained from lyophilized aqueous solution at pH 5 showed the presence of at least three conformers. The main conformer A (62%) is stabilized by an ionic interaction between the guanidinium and the C-terminal carboxylate groups, and the Pro⁶-Pro⁷ peptide bond adopts the cis form. A type II β-turn is also present in the N-terminal sequence (Pro¹-Pro-Gly-Met⁴-) of this conformer. Conformer B (21%) is also stabilized by a similar ionic interaction, as in conformer A, while the NMR data indicate the absence of a folded structure in the N-terminal tetrapeptide of this conformer. Conformer C (17%) adopts a completely extended structure. The multiple conformers of the P-P-G-M-R-P-P may offer some explanation for the reactivity of sera with various autoantibody specificities against this epitope. © Munksgaard 1996.     

Comparison of Signal-Averaged Electrocardiograms with Different Levels of Noise: Time-Domain, Frequency-Domain, and Spectrotemporal Analysis

In order tn test the effect of noise on the various parameters of the SAECG, 83 patients underwent three consecutive recordings at different noise levels. The high noise (HN) recordings had a noise level of 0.60–0.74 μV. the intermediate noise (IN) had 0.31–0.59 μV, and the low noise (LN) had ≤ 0.30 μV. For the calculation of noise we used the standard deviation of the mean noise of the composite lead high pass filtered at 40 Hz. The recordings were compared using time-domain, frequency-domain, and spectrotemporal analysis. The time-domain parameters of the LN recordings, using 25-Hz, 40-Hz, and 60-Hz high pass cutoffs, were significantly different from those of the HN or IN recordings (P < 0.05). In the frequency-domain analysis, significant differences were found in some of the parameters of the LN compared to the HN. The spectrotemporal analysis of the X and Z leads also showed significant differences among the LN and the other recordings. In the time-domain analysis, both at 40 Hz and 25 Hz, there were more abnormal LN compared to the HN recordings (P < 0.05). In the spectrotemporal analysis, there were significantly more abnormal HN and IN recordings compared to the LN (P < 0.001 and P < 0.01. respectively). Therefore, the level of noise, even within the acceptable range, can significantly affect the SAECG. In the time domain at the lower noise levels the parameters become more abnormal, while the opposite seems to occur in the spectral and the spectrotemporal analysis.     

Complete Heart Block in the Setting of Mitochondrial Cytopathy: Implantation of a Permanent Pacemaker in a 6-Year-Old Boy

The case of a 6-year-old boy with cytochrome oxidase (complex IV) deficiency and complete heart block, treated with permanent pacemaker implantation, is reported.     

Decreased CD3+CD16+ natural killer-like T-cell percentage and zeta-chain expression accompany chronic inflammation in haemodialysis patients

Aim:   Clinical and experimental data indicate a deficient immune response in haemodialysis (HD) patients. Natural killer-like (NKL) T cells express on their surface both the T-cell antigen receptor (TCR) and a diverse set of NK-cell receptors (NKR) and share properties of both T cells and NK cells. ζ-Chain phosphorylation is an early event that follows TCR activation or some NKR activation. The ζ-chain of both T cell and NK cells is downregulated in many chronic inflammatory states, HD included. In the present study, NKL T-cell percentage and ζ-chain expression in HD patients were evaluated.
Methods:   Thirty-three stable HD patients and 30 healthy volunteers were enrolled into the study. NKL T-cell percentage and NKL T-cell ζ-chain mean fluorescence intensity (MFI) were evaluated with flow cytometry. The inflammatory markers C-reactive protein, interleukin-6 and tumour necrosis factor-α were measured in the serum by means of enzyme-linked immunosorbent assay.
Results:   All the evaluated markers of inflammation were increased in HD patients. In these patients, NKL T-cell percentage (1.71 ± 1.69% vs 3.94 ± 3.86%) and ζ-chain MFI (3.66 ± 2.79 vs 7.03 ± 7.91) were decreased.
Conclusions:   NKL T-cell percentage and ζ-chain expression is decreased in HD patients. Taking into consideration the continuously increasing age of the HD patients and that normally NKL T-cell numbers increase with age counteracting the impaired T-cell and NK-cell function accompanying advancing age, the above NKL T-cell disturbances could contribute to the impaired immune response in this population. Measures towards alleviating chronic inflammation could partially restore NKL T-cell impairment.     

Ranolazine as a Promising Treatment Option for Atrial Fibrillation: Electrophysiologic Mechanisms,Experimental Evidence,and Clinical Implications

Currently available agents for pharmacologic management of atrial fibrillation (AF) are limited by their suboptimal efficacy and nonnegligible proarrhythmic risk. Ranolazine (RN) is a novel antianginal agent with increasingly appreciated antiarrhythmic properties that can suppress ventricular and supraventricular arrhythmias including AF. In this review, we describe the electrophysiological properties of RN, focusing on atrial‐selective inhibition of a number of ion channels implicated in the development of AF, particularly the sodium current. We further summarize evidence from experimental studies that demonstrate a potent AF‐suppressing effect of RN, alone or in combination with other antiarrhythmic drugs. Of clinical relevance, we present growing evidence from preliminary clinical investigations indicating the safety and efficacy of RN for prevention and treatment of AF in various clinical settings including prevention of AF in patients with acute coronary syndromes, prevention and conversion of postoperative AF after surgical coronary revascularization, sinus rhythm maintenance in drug‐resistant recurrent AF, and facilitating of electrical or pharmacological cardioversion in cardioversion‐resistant patients. While current experimental and clinical evidence points to RN as a potentially promising agent for suppression of AF, well‐designed, large‐scale trials will be required before RN can be considered for pharmacological treatment of AF in clinical practice.     

Pretreatment with Antithrombotic Agents During Radiofrequency Catheter Ablation: A Randomized Comparison of Aspirin Versus Ticlopidine

Aspirin Versus Ticlopidine in Radiofrequency Ablation. introduction: D-dimer is a product of fibrin degradation and can serve as a biochemical marker of thrombus formation and reactive fibrinolysis. According to our previous observations, and as reflected by elevated plasma D-dimer levels, lesions produced by radiofrequency (RF) ablation have a thrombogenic effect, Pretreatment with combined aspirin and ticlopidine mitigates this thrombogenicity; however, the effect of either agent alone remains unknown. Methods and Results: In this study, 59 patients undergoing RF ablation were randomized to pretreatment with aspirin (group I; n = 30) or ticlopidine (group II; n = 29) for 3 days prior to RF ablation. D-dimer levels were measured by enzyme immunoassay before and after the electrophysiologic study (EPS), and both immediately and at 48 hours after RF ablation. Results also were compared with those of 31 patients (nonrandomized group III) who bad received both aspirin and ticlopidine. At all stages, D-dimer levels were higher in groups I and II when compared with group III. Baseline D-dimer (31 ± 20 vs 24 ± 13 vs 17 ± 11 Mg/L, respectively; P= 0.002) rose after EPS to higher levels in groups I and II (91 ± 100 Mg/L and 51 ± 35 μg/L) compared with group III (31 ± 17 μg/L; P= 0.001). After RF ablation, D-dimer levels increased in all groups, but this increase was much higher in groups I and II (214 ± 210 μg/L and 201 ± 222 μg/L) than in group III (74 ± 60 μg/L; P= 0.005). At 48 hours, D-dimer levels decreased in all groups, but remained higher in groups I and II (91 ± 100 μg/L and 95 ± 99 μg/L) than in group III (35 ± 31 μg/L; P= 0.009). There were no differences among the three groups in the number of RF ablation lesions or the duration of the RF ablation procedure. Conclusion: Pretreatment with aspirin or ticlopidine alone does not decrease the thrombogenic potential of RF ablation. Only combined therapy with aspirin and ticlopidine has a favorable effect, as reflected by the lower degree of D-dimer elevation.