Electrocardiogram-Based Algorithm to Predict the Left Ventricular Lead Position in Recipients of Cardiac Resynchronization Systems

Introduction: Biventricular pacing is associated with various electrocardiographic patterns depending on the position of the left ventricular (LV) lead. We aimed to develop an electrocardiogram-based algorithm to predict the position of the LV lead.
Methods: The algorithm was developed in 100 consecutive recipients of cardiac resynchronization therapy (CRT) systems. QRS axis, morphology, and polarity were analyzed with a view to define the specific electrocardiographic characteristics associated with the various LV lead positions . The algorithm was prospectively validated in 50 consecutive CRT device recipients.
Results: The first analysis of the algorithm was the QRS morphology in V₁. A positive R wave in V₁ suggested LV lateral or posterior wall stimulation. A QS pattern was specific of anterior LV leads. In the presence of an R wave in V₁, V₆ was analyzed to distinguish between an inferior and anterior LV lead. Inferior leads were never associated with a positive V₆. To differentiate between lateral and posterior positions, we analyzed the pattern in V₂. Lateral leads were associated with an R morphology in V₁ and a negative V₂. Posterior leads were associated with an R morphology in V₁ and V₂. The algorithm allowed a reliable distinction between an inferior or anterior and a lateral or posterior lead position in 90% of patients. Inferior, anterior, lateral, and posterior positions were reliably distinguished in 80% of patients.
Conclusion: This algorithm predicted the position of the LV lead with a high sensitivity and predictive value.     

Left Ventricular Ejection Fraction as Criterion for Implantation of an Implantable Cardioverter-Defibrillator in Heart Failure Patients Undergoing Surgical Left Ventricular Reconstruction

Background: Besides implantation of an implantable cardioverter-defibrillator (ICD), a proportion of patients with left ventricular (LV) dysfunction due to ischemic cardiomyopathy are potential candidates for surgical LV reconstruction (Dor procedure), which changes LV ejection fraction (LVEF) considerably. In these patients, LVEF as selection criterium for ICD implantation may be difficult. This study aimed to determine the value of LVEF as criterium for ICD implantation in heart failure patients undergoing surgical LV reconstruction.
Methods: Consecutive patients with end-stage heart failure who underwent ICD implantation and LV reconstruction were evaluated. During admission, two-dimensional (2D) echocardiography (LV volumes and LVEF) was performed before surgery and was repeated at 3 months after surgery. Over a median follow-up of 18 months, the incidence of ICD therapy was evaluated.
Results: The study population consisted of 37 patients (59 ± 11 years). At baseline, mean LVEF was 23 ± 5%. Mean left ventricular end-systolic volume (LVESV) and left ventricular end-diastolic volume (LVEDV) were 175 ± 73 mL and 225 ± 88 mL, respectively. At 3-month follow-up, mean LVEF was 41 ± 9% (P < 0.0001 vs. baseline), and mean LVESV and LVEDV were 108 ± 65 mL and 176 ± 73 mL, respectively (P < 0.0001 vs. baseline). During 18-month follow-up, 12 (32%) patients had ventricular arrhythmias, resulting in appropriate ICD therapy. No significant relations existed between baseline LVEF (P = 0.77), LVEF at 3-month follow-up (P = 0.34), change in LVEF from baseline to 3-month follow-up (P = 0.28), and the occurrence of ICD therapy during 18-month follow-up.
Conclusion: LVEF before and after surgical LV reconstruction is of limited use as criterium for ICD implantation in patients with end-stage heart failure.     

POSTOPERATIVE ANALGESIA WITH EXTRADURAL CLONIDINE

The analgesic effect of extradural clonidine was evaluated ina double-blind study. In the recovery room, following orthopaedicor perineal surgery 20 ASA I and II patients were allocatedrandomly to two groups. The extradural clonidine (EC) groupreceived clonidine 2 µg kg^–1 in isotonic salinesolution 15 µg ml^–1. The extradural saline (ES)group received the equivalent volume of plain isotonic salinesolution. Pain was evaluated by a visual analogue scale (VAS)at 15-min intervals for the first 2 h and subsequently at 30-minintervals for the following 4 h. Morphine 5 mg was given s.c.when patients complained of pain after extradural saline orclonidine. In the EC group, the mean (SD) maximum pain reliefwas 68.2 (24.1)% of the initial VAS score, but it was only 14.7(25.2)% in the ES group. The mean duration of analgesia, beforeinjection of morphine, was significantly longer in the EC group(210 (87) min) compared with the ES group (45 (27) min) (P <0.001). Drowsiness and moderate hypotension were observed inthe EC group.     

N-Methyl peptides

The natural occurrence of N-methyl peptides in various plant metabolites has made N-methylation a subtle and attractive possible modification for structure-activity relationship studies of endogeneous peptides. However, little is known about the conformational specificity induced by the N-methylation of a given peptide, and particularly concerning the β-turn conformation. A spectroscopic investigation (i.r., n.m.r., CD) and X-ray diffraction experiments have been carried out on tBuCO-X-Me-Y-NHMe blocked dipeptides (X = Gly, L-Ala, L-Pro, and Y = Gly, and L- or D-Ala, Leu, Phe) with reference to the homologous desmethylated species. The influence of the N-methylation on conformation depends to a large extent on the chirality of the X and Y residues. Homochiral sequences are the most affected, with a strong preference for the βVI-folded conformation containing a middle cis amide bond. Heterochiral sequences are essentially unaffected and retain the βII-folded conformation with a trans middle amide bond. Glycine-containing sequences undergo a more complex perturbation according to the X or Y position of the Gly residue. The available data for larger N-methyl peptides are consistent with our observations, suggesting that these simple dipeptides well reflect the conformational perturbations induced by N-methylation on the β-turn conformation.     

Role of interstitial brachytherapy in oral and oropharyngeal carcinoma: Reflection of a series of 1344 patients treated at the time of initial presentation

Our study focuses on a series of 1344 cases of carcinoma of the oral cavity and oropharynx treated between 1973 and 1992. Brachytherapy was always performed with iridium 192, either alone or in combination with external-beam irradiation or with surgery for the treatment of the primary tumor. For the oral cavity, we studied 565 cases of mobile tongue. The local control and overall survival rates, respectively, at 5 years are as follows: for T1, 92% and 70%; for T2, 62% and 42%; and for T3, 50% and 29%. For the subgroup T1T2N0, there was a better prognosis for treatment by brachytherapy of the primary lesion alone (p < 0.0001). Two hundred seven cases of floor-of-mouth carcinoma have been reported. The T3T4 patients were not considered surgical candidates. The local control and overall survival rates, respectively, at 5 years are as follows: for T1, 97% and 71%; for T2, 72% and 42%; and for T3, 51% and 35%. Ninety-seven patients were treated by postoperative brachytherapy. These were patients for whom the margins after surgery were positive or narrow. A technique termed the modified bridge is described for lesions located in the mandible. Carcinomas of the buccal mucosa are rare in our country; only 42 cases were treated in this comparison of two techniques, and the overall survival rate was 48%. Epidermoid carcinomas of the oropharynx have nearly always been treated by a combination of external-beam irradiation and brachytherapy because of the bilateral node risk. Seventy-two patients with epidermoid cancers of the base of the tongue had an overall survival rate of 44%. The tonsil, soft palate, and pillars benefited from the use of the loop technique of brachytherapy combined with external-beam irradiation. Three hundred sixty-one patients were treated. Among these patients were two groups with different prognoses. Patients with tonsil, soft palate, and posterior pillar carcinomas had a local control rate of 84% and an overall survival rate of 57%. Conversely, the anterior pillar and the pharyngoglossal sulcus have a local control rate of only 65% and an overall survival rate of 38%.Statistical analysis revealed the prognostic factors for local control. The complications were classified into four grades: minor (20%), moderate (9%), major (4%), or inducing death (0.2%). The bone complications of grade 2 or 3 are more frequent for the floor of the mouth than for other locations. (Otolaryngol Head Neck Surg 1996:115:519-26.)     

Radiofrequency Catheter Ablation in Unusual Mechanisms of Atrial Fibrillation:

RF Catheter Ablation in AF. Introduction: The purpose of this study was to test the feasibility of radiofrequency (RF) catheter ablation of localized mechanisms of atrial fibrillation (AF).
Methods and Results: Three patients underwent RF catheter ablation for drug-resistant atrial arrhythmias. The first two patients had either incessant atrial tachycardia or AF. In the first patient, the KCG pattern of AF was mimicked by a very rapid atrial focus, whereas in the second patient, AF was due to true degeneration of the atrial activity triggered by atrial tachycardia. In both patients, the ablation of atrial focus led to the clinical disappearance of AF. The third patient had frequent episodes of AF, which lasted several days or weeks, and two documented episodes of atrial flutter. Mapping during AF showed an irregular atrial rhythm in the atrial septum, particularly in the region surrounding the coronary sinus, whereas the entire lateral right atrial free wall exhibited a constantly organized rhythm. RF energy was applied between the tricuspid ring and both the inferior vena cava and the coronary sinus, resulting in inability to reinduceatrial flutter or sustained AF. A 6-month follow-up in this patient showed the disappearance of prolonged episodes of AF.
Conclusion: The observations indicate that AF may be linked to "focal" mechanisms that can be treated by RF catheter ablation.     

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.     

Ψ[CH2O] pseudodipeptide synthesis An improved approach which allows absolute configuration determination

An improved way to obtain Ψ[CH₂O] pseudodipeptide units is proposed, involving an intramolecular Williamson's reaction, with displacement of bromine by an alkoxide, instead of the classical intermolecular one. Until now, Ψ[CH₂O] pseudodipeptide synthesis done by this new method, has used a protected form of the amino alcohol hydroxyl group to prepare the acyclic precursor. In the present paper, the use of an active ester of the brominated carboxylic acid avoids this protection step. The pseudodipeptides Ac-GlyΨ[CH₂O]-d,l -Ala-OH and Ac-Ser(Bzl)Ψ[CH₂O]-d,l -Ala-OH were obtained in high yields, through a delta-lactam intermediate, which furthermore allows the determination of the absolute configuration of compounds using HPLC and appropriate nuclear magnetic resonance (NMR) techniques.