Epicardial repolarization mapping in man

A simple method was developed for recording epicardial monophasicaction potentials intraoperatively in man. Potentials were recordedrapidly and reliably from multiple epicardial sites using ahand-held probe. The feasibility of repolarization mapping wasassessed in 30 patients. It was possible to record technicallyadequate signals from most left ventricular and posterior rightventricular sites (success rates 72% and 61%, respectively),but it was more difficult to achieve satisfactory recordingsover the free wall of the right ventricle (success rate 36%).The onset of cardiopulmonary bypass resulted in a transientrise in action potential duration of approximately 30–40ms in the first minutes of bypass. An approximate steady statewas achieved thereafter. Reproducibility of the method was assessedby mapping a small number of sites repeatedly. The 95% confidencelimits for an estimate of repolarization time, based on a singlepotential, were ±21 ms. With 4 probe applications ateach site, the confidence limits of the estimated site meanwere reduced to ±8 ms. Based on this approach, statisticallysignificant differences between sites were demonstrated in 9of 10 patients, confirming that the method is sensitive enoughto provide information on regional differences in repolarization. Intraoperative epicardial repolarization mapping has been shownto be a practical possibility. The technique holds promise asa means of assessing the role of dispersion of repolarizationin arrhythmogenesis in man.     

Occurrence of infection among children with nephrotic syndrome during hospitalizations

Aim: The present study was conducted to investigate the trends of childhood nephrotic syndrome (NS) admissions and factors associated with childhood NS admissions with major infections in Taiwan. Methods: A retrospective analysis was performed using Taiwan National Health Research Insurance Database (NHIRD) to explore the associated factors and health care burden for childhood NS admissions with major infections in 1997 to 2007. Results: Of 133 927 children, a total of 176 children had NS, which incurred 508 hospital admissions. Nineteen percent of admissions were associated with major infections. Pneumonia was the most common infection (49%), followed by urinary tract infection (UTI), bacteraemia/sepsis, peritonitis and cellulitis. Pneumonia was the most common infection among children age younger than 10 years, whereas UTI was more common among children aged greater than 10 years. NS admission with infections had longer periods of hospital length of stay and higher hospital total costs compared to those without infections. Regression analysis reveals that younger age, regional hospitals, admission hospital located in middle and south areas and admission made in spring were associated with increased risk for developing major infections. Conclusions: While 19% of childhood NS admissions were associated with major infections, young age, admissions made in spring, located in middle and south Taiwan and in regional hospitals were the major associated factors for infection. Age plays an important role in risk and types of infection.     

Susceptibility of N''Dama and Boran cattle to tsetse-transmitted primary and rechallenge infections with a homologous serodeme of Trypanosoma congolense

Eight trypanotolerant N'Dama cattle controlled an infection of Trypanosoma congolense ILNat 3.1 transmitted by Glossina morsitans centralis, more efficiently than a group of similarly infected trypanosusceptible Boran cattle. All eight N'Damas maintained their PCV above 15% throughout the primary infection whereas the PCV of six of the eight Borans dropped below 15%; these latter animals were treated with diminazene aceturate to prevent possible death. Lymphocyte, neutrophil and platelet counts also decreased in the Boran during the primary infection. In contrast, a lymphocytosis was observed in the N'Dama; and although the neutrophil and platelet counts decreased, the drop was less severe than in the Boran. Two years after the primary infection and immediately prior to a homologous rechallenge infection, all eight N'Damas had neutralizing anti-metacyclic trypanosome variant-specific antibodies present in their sera compared to five of the eight Borans. Following the homologous rechallenge infection the eight N'Damas became parasitaemic but there were no alterations in their erythrocyte or leukocyte counts. The Borans became highly parasitaemic and developed severe, chronic anaemia and leukopaenia. Thus, the trypanotolerant N'Damas controlled a primary infection of T. congolense more efficiently than trypanosusceptible Boran cattle and eliminated a homologous rechallenge infection without the pathology associated with the disease.     

Is the Outcome of Coronary Stenting Worse in Elderly Patients?

Initial reports of percutaneous transluminal coronary angioplasty (PTCA) in the elderly (≥: 75 years) showed a significantly lower primary success rate, higher in-hospital mortality, and a higher risk of emergency or elective coronary artery bypass graft (CABG) compared to younger patients. There are few data concerning acute outcomes and clinical follow-up after the use of coronary stenting in the elderly compared to < the 75-year-old age group. We evaluated 82 elderly patients and 280 younger patients who received Palmaz-Schatz stents during 1995, at a time when high pressure deployment and antiplatelet therapy was routinely used. The success rate and acute major complications were not significantly different between the elderly and younger patients. Clinical events (death, myocardial infarction [MI], repeat PTCA, or CABG) during 6-month follow-up were also not significantly different. Coronary stenting in the elderly can be carried out with a high success rate and low incidence of acute major complications. Thus, short-term clinical outcomes in elderly patients appear similar to results obtained in younger patients.     

Mechanism-Specific Therapy of Ventricular Tachycardia

Arrhythmia Mechanisms and Therapy. An understanding of the mechanisms responsible for experimental and clinical arrhythmias has led to the development of mechanism-specific therapies for ventricular tachycardia. These include: (1) beta blockade for catecholamine-sensitive ventricular tachycardia; (2) verapamil for ventricular tachycardia possibly due to triggered activity; (3) pacing, isoproterenol and magnesium therapy for torsade de pointes possibly due to early afterdepolarizations; (4) catheter ablation of the right bundle for bundle branch reentry tachycardia; and (5) catheter ablation of the zone of slow conduction for ventricular tachycardia due to reentry. Hopefully, further progress will be made in removing some of the empiricism from antiarrhythmic therapy.     

The Response of Paroxysmal Supraventricular Tachycardia to Overdrive Atrial and Ventricular Pacing:

Pacing During Supraventricular Tachycardia. Introduction: Standard electrophysiologic techniques generally allow discrimination among mechanisms of paroxysmal Supraventricular tachycardia. The purpose of this study was to determine whether the response of paroxysmal Supraventricular tachycardia to atrial and ventricular overdrive pacing can help determine the tachycardia mechanism. Methods and Results: Fifty-three patients with paroxysmal Supraventricular tachycardia were studied. Twenty-two patients had the typical form of atrioventricular (AV) junctional (nodal) reentry, 18 patients had orthodromic AV reentrant tachycardia, 10 patients had atrial tachycardia, and 3 patients had the atypical form of AV nodal reentrant tachycardia. After paroxysmal Supraventricular tachycardia was induced, 15-beat trains were introduced in the high right atrium and right ventricular apex sequentially with cycle lengths beginning 10 msec shorter than the spontaneous tachycardia cycle length. The pacing cycle length was shortened in successive trains until a cycle of 200 msec was reached or until tachycardia was terminated. Several responses of paroxysmal Supraventricular tachycardia to overdrive pacing were useful in distinguishing atrial tachycardia from other mechanisms of paroxysmal Supraventricular tachycardia. During decremental atrial overdrive pacing, the curve relating the pacing cycle length to the VA interval on the first beat following the cessation of atrial pacing was flat or upsloping in patients with AV junctional reentry or AV reentrant tachycardia, but variable in patients with atrial tachycardia. AV reentry and AV junctional reentry could always be terminated by overdrive ventricular pacing whereas atrial tachycardia was terminated in only one of ten patients (P < 0.001). The curve relting the ventricular pacing cycle length to the VA interval on the first postpacing beat was flat or upsloping in patients with AV junctional reentry and AV reentry, but variable in patients with atrial tachycardia. The typical form of AV junctional reentry could occasionally be distinguished from other forms of paroxysmal Supraventricular tachycardia by the shortening of the AH interval following tachycardia termination during constant rate atrial pacing. Conclusions: Atrial and ventricular overdrive pacing can rapidly and reliably distinguish atrial tachycardia from other mechanisms of paroxysmal Supraventricular tachycardia and occasionally assist in the diagnosis of other tachycardia mechanisms. In particular, the ability to exclude atrial tachycardia as a potential mechanism for paroxysmal Supraventricular tachycardia has important implications for the use of catheter ablation techniques to cure paroxysmal Supraventricular tachycardia.