[Impact of thoracic irradiation on cardiac structures]

Thoracic irradiation requires protection of the heart as an organ at risk of complications. The mean heart dose is the most studied dosimetric parameter in the literature. Recent studies question its relevance in view of the multiplicity of cardiac injuries, the heterogeneity of the cardiac dose distribution and the current technical possibilities to refine cardiac dosimetric protection. The objective of this literature review is to analyze the available scientific data on the impact of the dose received by the cardiac substructures. A search of articles using the PubMed search engine was used to select the most relevant studies. A total of 19 articles were selected according to pre-established criteria to answer the issue. Several studies found significant associations between dosimetric parameters of substructures and clinical cardiological impact. Some proposed dose constraints for substructures.

[Alternating bundle branch block in a supraventricular tachycardia: Which is the mechanism ?]

Functional bundle branch block during a supraventricular tachycardia can be observed with shorter cycle lengths and represent a physiologic response by the specialized intraventricular conduction system to accelerated AV nodal conduction. The present case corresponds to a young patient with exercise induced orthodromic A-V reentrant tachycardia and alternating bundle branch block. This unusual response is explained by the finding obtained during the electrophysiology study. An accelerated AV nodal conduction made the depolarizing wave front reach the bundle branches during their refractory period. Once block in one bundle was stablished, block persisted due to the linking phenomenon that is repetitive retrograde concealed conduction from the contralateral bundle. After catheter ablation of a concealed left-sided accessory A-V pathway, rapid atrial pacing at the same cycle length of the tachycardia reproduced the same aberrancies observed during tachycardia. This response proved that functional bundle branch block is due to the short cycle length and not the presence of an accessory A-V pathway.

Two-site evaluation of the diagnostic performance of the Sysmex XN Body Fluid (BF) module for cell count and differential in Cerebrospinal Fluid

INTRODUCTION

Cellular analysis in cerebrospinal fluid (CSF) provides important diagnostic information in many pathological settings. The aim of this two-site study was to evaluate the Sysmex XN Body Fluid mode (XN-BF) for cell analysis of CSF compared to light microscopy (LM).

METHODS

Two hundred and seven consecutive CSF samples were analyzed in parallel with XN-BF and LM. The study also included the estimation of the limit of blank (LoB), limit of detection (LoD), limit of quantitation (LoQ), carry-over and linearity of XN-BF module.

RESULTS

LoQ of white blood cells (WBC) was 3×10⁶  cells/L; linearity was good and carry-over negligible. XN-BF parameters were compared to LM for the following cell classes: total cells, WBC, polymorphonuclear (PMN), and mononuclear (MN) cells. The bias ranged from 1.3 to 15.2×10⁶  cells/L. The receiver operating characteristics curve analysis for WBC showed an area under the curve of 0.98, and the global diagnostic agreement was 95% at a cutoff of 5×10⁶  cells/L.

CONCLUSIONS

XN-BF provides rapid and accurate counts in clinically relevant ranges of CSF values, thus providing a valuable alternative to conventional LM analysis. However, microscopic review remains advisable in samples with abnormal cell counts or high fluorescent (HF-BF) cell parameter exceeding 5×10⁶  cells/L.

[Induction of atrioventricular nodal reentrant tachycardia by radiofrequency application]

Atrioventricular nodal reentrant tachycardia is the most common form of sustained regular narrow QRS complex tachycardia. It is caused by the presence of a dual atrioventricular nodal anatomy and physiology, with a fast and a slow pathway forming a substrate for re-entry. Electrophysiology study confirms the diagnosis when the tachycardia is induced, although in some cases this is not possible. Casuistry is here presented where the application of radiofrequency induced atrioventricular nodal reentrant tachycardia, when the electrophysiological study could not do it; we explain here its electrophysiological mechanism.

[Lesions produced by radiofrequency ablation of the cavotricuspid isthmus in an experimental model]

INTRODUCTION AND OBJECTIVES

Experimental studies have shown that deeper and wider lesions (up to 10 mm long or deep) can be safely created using an 8 mm or irrigated tip catheter for ablation to treat atrial flutter. However, potential damage to the tricuspid valve or inferior cava vein has not been systematically evaluated.

PATIENTS AND METHOD

The cavotricuspid isthmus was ablated in 26 pigs (body weight 26-52 kg), with a total of 187 radiofrequency pulses. Standard 4 mm, 8 mm and irrigated tip catheters were used at random. For each ablation, energy, impedance and temperature were recorded continuously.

RESULTS

The lesions were larger with irrigated tip and 8-mm catheters than with standard ones. In 7 animals (1 with an irrigated tip, 4 with an 8-mm, and 2 with a standard tip) the tricuspid valve was damaged. The tricuspid valve was severely damaged in 3 pigs and lesions were moderate in 4. In animals with tricuspid valve lesions, maximal energy was higher (59 +/- 27 vs. 51 +/- 24 W; p=0,03) and higher temperatures were reached (63 +/- 4 vs. 55 +/- 11 degrees C; p<0.001). Low energy pulses measured before ablation were also more intense in animals in which damage was produced (0.55 +/- 0.24 vs. 0.35 +/- 0.29; p=0.001), indicating greater contact pressure.

CONCLUSIONS

The tricuspid valve may be severely damaged during the ablation of the cavotricuspid isthmus for atrial flutter: damage was seen most often with high energy pulses and with 8-mm catheters, but can also occur with usual energy levels and standard catheters. To minimize damage this technique should not be used from the inside of the right ventricle just above the tricuspid valve.

Angiotensin Receptor Blocker as Adjunctive Therapy for Rhythm Control in Atrial Fibrillation: Results of the Irbesartan-Amiodarone Trial

Atrial fibrillation (AF) is a common arrhythmia associated with increased risk of stroke and mortality. The early appearance of electrical remodeling is followed by structural remodeling of the atrial tissue. Direct current cardioversion of persistent AF is the most effective treatment for the restoration of sinus rhythm, but it is hampered by a high percentage of recurrences. Recurrences may be the consequence of both electrical and structural remodeling. A study on the use of irbesartan to maintain sinus rhythm in patients with long-lasting persistent AF showed that this angiotensin II receptor blocker combined with amiodarone prolonged sinus rhythm after cardioversion. Irbesartan may have antifibrotic effects due not only to the ability to diminish the synthesis of collagen type I molecules but also to its capacity to stimulate the degradation of collagen type I fibers, as has been demonstrated with losartan, another angiotensin II receptor blocker. This suggests that efforts to reduce the structural changes that occur during AF may be more useful in preventing recurrences than efforts designed to minimize the electrical changes alone. The AFFIRM trial compared two approaches to the treatment of AF: cardioversion with antiarrhythmic drugs to maintain sinus rhythm and the use of rate-controlling drugs. The results show that management of AF with the rhythm-control strategy offers no survival advantage over the rate-control strategy. However, non-antiarrhythmic drugs to prevent recurrences, like irbesartan, were not controlled and amiodarone was used in a low percentage of the patients. The treatment strategies proposed in both AFFIRM and RACE, in our opinion, may not be the optimal. The modern clinical approach to AF involves an early intervention to restore sinus rhythm, therefore preventing atrial remodeling. The pretreatment of patients with AF who undergo electrical cardioversion is very important and will be the subject for continuous improvement.

Mother's knowledge of, attitudes toward, and management of fever in preschool children in Italy

BACKGROUND

We examined mothers' knowledge of, attitudes toward, and management of fever in their children.

METHODS

Interviews of mothers of preschool children were performed using a structured questionnaire administered by interviewers with no specific medical competence.

RESULTS

Of a total of 1,237 mothers who were interviewed, data were analyzed for the 707 mothers who had coped with a febrile episode in their children during the previous month. Of these, 59% were concerned about fever in their children and 17% were very worried. At the onset of fever, 48% of the mothers gave their child an antipyretic and 18% called the physician immediately. In logistic regression analysis, five variables were significantly associated with mothers' concern: the absence of previous information on the management of fever, temperature > 39 degrees C, an only child, mother's low educational level, and mother's residency in the south of Italy. For the request for a physician's visit, of the variables entered, the only explanatory ones were the mother's concern and the absence of previous information on the management of fever.

CONCLUSIONS

These findings suggest that informing mothers on the definition, consequences, and treatment of fever can significantly improve their confidence in managing fever, as reflected by fewer requests for physicians' visits.