Treatment of macro-re-entrant atrial tachycardia based on electroanatomic mapping: identification and ablation of the mid-diastolic isthmus.

AIMS: This multicentre prospective study evaluated the ability of electroanatomic mapping (EAM) using a specific parameter setting to identify clearly the mid-diastolically activated isthmus (MDAI) and guide ablation of macro-re-entrant atrial tachycardia (MAT). METHODS AND RESULTS: Consecutive patients with MAT, different from typical isthmus-dependent atrial flutter, were enrolled. EAM was performed using a specific setting of the window of interest, calculated to identify the MDAI and guide ablation of this area. Sixty-five patients exhibiting 81 MATs (mean cycle length 308 +/- 68 ms) were considered. Thirty-two (49.2%) had previous heart surgery. In 79 of 81 morphologies (97.5%), EAM reconstructed 95.9 +/- 4.3% of the tachycardia circuit and identified the MDAI; 23 of the 79 morphologies (29.1%) were double-loop re-entry. Mapping of two morphologies was incomplete due to MAT termination after catheter bumping. In 73 of 79 mapped morphologies (92.4%), abolition of the MAT was obtained by 13.2 +/- 12.4 applications. During the 14 +/- 4 month follow-up, MAT recurred in 4 of the successfully treated patients (6.8%). CONCLUSION: EAM using a specific parameter setting proved highly effective at identifying the MDAI in MAT, even in patients with previous surgery and multiple re-entrant loops. Ablation of the MDAI yielded acute arrhythmia suppression with low rate of recurrence during follow-up.     

An evaluation of the strategy of maintenance of sinus rhythm by antiarrhythmic drug therapy after ablation and pacing therapy in patients with paroxysmal atrial fibrillation.

AIMS: Permanent atrial fibrillation develops in many patients after ablation and pacing therapy. We compared a strategy that initially allowed patients to remain in atrial fibrillation with a strategy that initially attempted to restore and maintain sinus rhythm. METHODS AND RESULTS: In this multicentre randomized controlled trial, 68 patients affected by severely symptomatic paroxysmal atrial fibrillation were assigned, after successful atrioventricular junction ablation and pacing treatment, to antiarrhythmic drug therapy with amiodarone, propafenone, flecainide or sotalol and were compared with 69 patients assigned, after successful AV junction ablation and pacing treatment, to no antiarrhythmic drug therapy. The patients were followed-up for 12 to 24 months (mean 16+/-4). The drug arm patients had a 57% reduction in the risk of developing permanent atrial fibrillation (21% vs 37%, P=0.02). Evaluation after 12 months revealed similar quality of life scores and echocardiographic parameters in the two groups, but the drug arm patients had more episodes of heart failure and hospitalizations (P=0.05). The outcome was similar between the 40 patients who developed permanent atrial fibrillation and the 97 who did not. CONCLUSION: Conventional antiarrhythmic therapy reduces the risk of development of permanent atrial fibrillation after ablation and pacing therapy. The present data do not support the concept that the development of permanent atrial fibrillation is related to an adverse outcome when a perfect control of heart rate is obtained by ablation and pacing.     

Respiratory symptoms,asthma, atopy and Chlamydia pneumoniae IgG antibodies in a general population sample of young adults

Background: This study was designed to test the association of Chlamydia pneumoniae infection with respiratory symptoms and atopy. Methods: A general population sample of 369 young adults (aged 20-44 years) completed a questionnaire on respiratory symptoms and underwent skin prick testing. C pneumoniae IgG and IgM serum titers were measured by micro-immunofluorescence. Prior infection was defined by titers of IgG ≥ 1:32, acute infection by titers of IgG ≥ :512 and/or IgM ≥ 1:16. Results: The prevalence of cough and phlegm was higher in subjects with (19.0%) than in those without (11.4%) prior C. pneumoniae infection (p = 0.01). A similar difference was found for wheezing (14.3% vs 8.0%; p = 0.05), whereas the percentage of asthmatics was equally distributed between seropositive and seronegative subjects. IgG titers ≥ 1:128 were found more frequently in atopic subjects (p = 0.04). After adjusting for any confounding factors, cough and phlegm (but not wheezing) were found significantly associated with C. pneumoniae positivity, both for 1 : 32 (OR 1.80; 95% CI: 1.01-3.36; p = 0.05) and for 1 : 128 titers (OR 2.31; 95% CI: 1.20-4.42; p = 0.01). A significant association was also found for atopy, for titers ≥ 1 : 128 (OR 1.73; 95% CI: 1.01-3.20, p = 0.05). Acute infection was not associated with respiratory symptoms or asthma. Conclusion: We conclude that C. pneumoniae infection is associated with cough and phlegm and may have a role in the pathogenesis of chronic respiratory diseases. Moreover, our results indicate a relationship between atopy and C. pneumoniae infection. Received: October 9, 2001 · Revision accepted: March 3, 2002     

Haemodynamic effects of withdrawal of efferent cervical vagal stimulation on anesthetized dogs--relative importance of chronotropic and non-chronotropic mechanisms

The aim of the present work was to study changes in cardiac output (CO) and arterial blood pressure (ABP) following either interruption of artificial efferent vagal stimulations (STOP), or suppression of negative chronotropic effects, during uninterrupted vagal stimulations (PACE). Experiments were performed on 7 anesthetized, open-chest dogs. A computerized data acquisition system was used to record CO (electromagnetic flowmeter), ABP, right atrial pressure and electrocardiogram; 9 parameters were automatically elaborated. The peripheral stumps of both vagus nerves, sectioned at the neck, were stimulated for long control periods (at least 3 min) with brief trains of stimuli triggered by atrial P waves. Records were started during steady-state vagal stimulations, and consisted of paired trials: in the first step the vagal stimulators were turned off (STOP); in the second step the heart was paced at the same rate reached at the end of the preceding step, but vagal stimulation was continued (PACE). Observations lasted two min after each step. Results indicate rapid rise in CO and ABP after STOP, up to 30% and 10%, respectively, in 10 s, followed by slow reduction in CO and further increase in ABP (22% and 15%, respectively, at 120 s). Thus STOP caused rapid and sustained improvements in the cardiac performance. After PACE changes in CO and ABP were smaller and followed a slower time-course. The greater effects of STOP with respect to PACE were attributed to non-chronotropic mechanisms, accounting for about 50% of the overall haemodynamic consequences of vagal withdrawal. Since peak aortic flow velocity and acceleration were increased after STOP, stroke volume was reduced much less than after PACE, despite equal rise in heart rate, and similar shortening in the ejection time. Evidence was presented of enhanced atrial and ventricular contractility after STOP. Experiments performed after beta-blockade in 5 dogs substantially confirmed the results. It is concluded that vagal withdrawal, which is an important aspect in many physiological situations, constitutes a rather powerful strategy for rapid enhancement of the cardiovascular performance, through different mechanisms, in addition to cardioacceleration.     

Rare complications during surgical vein cannulation in extremely low birthweight neonates

Extremely low birthweight neonates often require total parenteral nutrition by central venous catheterization.The technique of choice is the percutaneous cannulation via the basilica or cephalic vein; in particular cases, these peculiar patients need a cut down catheterization. This paper describes some unusual complications of this surgical approach.     

Providing the Best Parenteral Nutrition before and after Surgery for NEC: Macro and Micronutrients Intakes

Necrotizing enterocolitis (NEC) is the main gastrointestinal emergency of preterm infants for whom bowel rest and parenteral nutrition (PN) is essential. Despite the improvements in neonatal care, the incidence of NEC remains high (11% in preterm newborns with a birth weight <1500 g) and up to 20–50% of cases still require surgery. In this narrative review, we report how to optimize PN in severe NEC requiring surgery. PN should begin as soon as possible in the acute phase: close fluid monitoring is advocated to maintain volemia, however fluid overload and electrolytes abnormalities should be prevented. Macronutrients intake (protein, glucose, and lipids) should be adequately guaranteed and is essential in each phase of the disease. Composite lipid emulsion should be the first choice to reduce the risk of parenteral nutrition associated liver disease (PNALD). Vitamin and trace elements deficiency or overload are frequent in long-term PN, therefore careful monitoring should be planned starting from the recovery phase to adjust their parenteral intake. Neonatologists must be aware of the role of nutrition especially in patients requiring long-term PN to sustain growth, limiting possible adverse effects and long-term deficiencies.