Internal Cardioversion of Chronic Atrial Fibrillation in Patients

Transvenous internal cardioversion of chronic AF using a right atrium (RA) coronary sinus (CS) vector requires more energy than cardioversion of paroxysmal AF. Chronic AF is not terminated in 25% of patients using biphasic shocks up to 10 J. We therefore evaluated efficacy, safety, and tolerability of internal cardioversion using a "unipolar' configuration (RA to skin patch) and biphasic shocks in patients with long-lasting AF and different heart disease. In each patient, biphasic R have synchronous shocks were delivered between a large defibrillating surface area electrode in the RA and a skin patch in the left prepectoral position. Defibrillation protocol started with a test shock of 0.4 J. Shocks were repeated and increased until termination of AF or a maximum of 34 J. Sedation was used when the patient described the shock as painful. This study included 11 patients with a mean age of 67 ± 8 years (range 56–83). AF duration was ± 1 month in all patients with a mean duration of 11 ± 11 months (range 2–36). Underlying heart disease was present in all patients and the mean left atrial dimension was 43 ± 9 mm (range 26–57). AF was terminated in 10 of 11 patients (91 %) with a mean delivered energy of the successful shocks of 18.7 ± 8.7 J (median energy 16.9 J; range 7.3–32.5) and a mean leading edge voltage of 564 ± 129 V. The mean shock impedance at the defibrillation threshold was 71 ± 13 Ω, (range 59–103). A total of 131 shocks were delivered without any complication and proarrhythmia episodes. We conclude that low energy "unipolar" internal cardioversion is a simple, safe, and effective technique for termination of chronic AF in patients with heart disease. The procedure is often tolerated under light sedation.     

The destruction of virulent Entamoeba histolytica by activated human eosinophils

Unlike normal (i.e., non-activated) human eosinophils that are unable to destroy virulent Entamoeba histolytica even in the presence of antibodies and complement, activated eosinophils effectively destroy the parasite in vitro without the help of opsonins, yet increase this capacity with their assistance. Many activated eosinophils succumb in the process as well, probably victims of toxic products released by dying amoebae. Human activated eosinophils thus behave more like activated macrophages than like neutrophil polymorphonuclear leucocytes that are notoriously incompetent in dealing with virulent amoebae. As a regular constituent of early inflammatory reactions, and notwithstanding the absence of blood and tissue eosinophilia in invasive amoebiasis, the activated eosinophil may play a role in the defence against E. histolytica.     

MICROSATELLITE INSTABILITY IN INTESTINAL- AND DIFFUSE-TYPE GASTRIC CARCINOMA

To investigate the role of genetic instability in the development of intestinal- and diffuse-type gastric cancers, six microsatellite loci were analysed in 98 carcinomas of the two main histotypes, at both early and advanced stages of progression, and in five preneoplastic lesions. RER+ phenotype frequency proved to be significantly higher ( P =0·013) in intestinal (23 per cent) than in diffuse cancers (5 per cent) and slightly higher in advanced (19 per cent) than in early (12 per cent) tumours. When comparing early and advanced tumours of the same histotype, a similar frequency was found for diffuse tumours (4 per cent vs. 6 per cent), and an increase from 19 to 30 per cent for intestinal cancers. Instability at more than one locus was limited to intestinal tumours and replication errors were also detected in an intestinal dysplasia. On the whole, these data suggest that genetic instability has an important and early role in gastric carcinogenesis of the intestinal type and a less important role in gastric carcinogenesis of the diffuse type. Most tumours of this panel had previously been characterized for p53 gene mutations. p53 screening was extended to all samples, to investigate the possible association between gene mutations and microsatellite instability. Analysis showed a trend ( P =0·07, Fisher's exact test) towards a negative association between these two genetic lesions in tumours of the intestinal type. © 1997 John Wiley & Sons, Ltd.     

Contact versus Noncontact Mapping for Ablation of Ventricular Tachycardia in Patients with Previous Myocardial Infarction

Introduction: The aim of this study was to compare contact versus noncontact mapping for radiofrequency (RF) ablation of any sustained post-myocardial infarction (MI) ventricular tachycardia (VT).
Methods: Forty patients with tolerated VT post-MI were randomized to RF ablation with contact (group 1) or noncontact (group 2) mapping systems. In both groups ablation of tolerated VT was guided by VT activation map confirmed by concealed entrainment. When untolerated VTs were induced, ablation was performed in group 1 according to pace mapping starting from the scar border zone and in group 2 according to the VT activation map confirmed by pace mapping.
Results: No differences were seen between the groups in terms of acute success rate of clinical VT ablation (95% vs 100%, respectively; P = ns) and in the noninducibility of any VT at the end of the procedure (55% vs 85%, respectively; P = 0.08). Moreover, untolerated VTs were eliminated in 30% of group 1 versus 83.3% of group 2 patients (P < 0.05). The mean total procedural and fluoroscopy times were 236.4 ± 42.7 and 29.0 ± 7.8 minutes in group 1 and 144.5 ± 50.8 and 23.4 ± 5.8 minutes in group 2 (P < 0.001 and < 0.05, respectively). At a mean follow-up of 15.2 ± 6.7 months no differences were seen in VT recurrences between groups, but noninducibility at the end of the procedure was predictive of freedom from recurrences (P < 0.001).
Conclusion: Both systems are useful for ablation of tolerated VT. Noncontact mapping is more effective for ablation of untolerated VT and allows the reduction of procedural and fluoroscopy times. Noninducibility at the end of the procedure seems predictive of freedom from recurrences during follow-up.     

Multicenter Experiences with a Single Lead Electrode for Dual Chamber ICD Systems

Monitoring of atrial signals improves the accuracy in identifying supraventricular tachyarrhythmias to prevent inappropriate therapies in patients with implantable ICDs. Since difficulties due to the additional atrial lead were found in dual chamber ICD systems with two leads, the authors designed a single pass VDD lead for use with dual chamber ICDs. After a successful animal study, the prototype VDD lead (single coil defibrillation lead with two additional fractally coated rings for bipolar sensing in the atrium) was temporarily used in 30 patients during a German multicenter study. Atrial and ventricular signals were recorded during sinus rhythm (SR), atrial flutter, AF, and VT or VF. The implantation of the lead was successful in 27 of 30 patients. Mean atrial pacing threshold was 2.5 +/- 0.9 V/0.5 ms, mean atrial impedance was 213 +/- 31 ohms. Atrial amplitudes were greater during SR (2.7 +/- 1.6 mV) than during atrial flutter (1.46 +/- 0.3 mV, P < 0.05) or AF (0.93 +/- 0.37 mV, P < 0.01). During VF atrial "sinus" signals had significantly (P < 0.01) lower amplitudes (1.4 +/- 0.52 mV) than during SR. The mean ventricular sensing was 13.3 +/- 7.9 mV and mean ventricular impedance was 577 +/- 64 ohms. Defibrillation was successful with a 20-J shock in all patients. In addition, 99.6% of P waves could be detected in SR and 84.4% of flutter waves during atrial flutter. During AF, 56.6% of atrial signals could be detected without modification of the signal amplifier. In conclusion, a new designed VDD dual chamber lead provides stable detection of atrial and ventricular signals during SR and atrial flutter. Reliable detection of atrial signals is possible without modification of the ICD amplifier.