Association of rs2200733 at 4q25 with atrial flutter/fibrillation diseases in an Italian population.

BACKGROUND: Atrial fibrillation (AF) and atrial flutter (AFL) are common cardiac conduction disorders affecting many people. Recent studies on sporadic cases of AF/AFL showed a significant association of the single nucleotide polymorphism rs2200733T with the disease, suggesting a genetic factor in the development of the disease. OBJECTIVES: To determine the association of rs2200733 with AF/AFL derived from an Italian population sample. SUBJECTS: 78 patients with AF/AFL and 348 controls took part in the study. DESIGN: Genetic case-control study. RESULTS: The results indicate that there is a positive, significant association between the rs2200733 T allele and patients with AF/AFL of Italian origin (allelic p<0.001 with OR = 2.17). CONCLUSION: These results derived from a sample of the Italian population agree with previously reported findings from an Icelandic study, which also found that the minor allele rs2200733 was associated with AF/AFL disease.

Reuse of ground waste glass as aggregate for mortars.

This work was aimed at studying the possibility of reusing waste glass from crushed containers and building demolition as aggregate for preparing mortars and concrete. At present, this kind of reuse is still not common due to the risk of alkali-silica reaction between the alkalis of cement and silica of the waste glass. This expansive reaction can cause great problems of cracking and, consequently, it can be extremely deleterious for the durability of mortar and concrete. However, data reported in the literature show that if the waste glass is finely ground, under 75mum, this effect does not occur and mortar durability is guaranteed. Therefore, in this work the possible reactivity of waste glass with the cement paste in mortars was verified, by varying the particle size of the finely ground waste glass. No reaction has been detected with particle size up to 100mum thus indicating the feasibility of the waste glass reuse as fine aggregate in mortars and concrete. In addition, waste glass seems to positively contribute to the mortar micro-structural properties resulting in an evident improvement of its mechanical performance.

Different atrial regional patterns of activation during atrial fibrillation: is there any relationship with the anatomy?

Right atrial (RA) mapping has been recently more carefully examined in patients with idiopathic atrial fibrillation (AF) in order to improve radiofrequency (RF) catheter-mediated ablation lines to control recurrences. The aim of this study was to map right atrial activation during AF to analyze relationship between anatomy and atrial activation for specific sites. Twenty-four patients with recurrent, drug-refractory, paroxysmal AF underwent an extensive mapping of the RA before attempting RF linear lesion catheter ablation. A typical pattern of atrial activation was recorded in all patients which was consistent with a more regular activity on the trabeculated right atrium (type I AF) and a more fragmented and complex activation on the posterior and the anterior septum (type II and III AF). This paper helps to understand the influence of the anatomic barriers to atrial activation during atrial fibrillation.

Effects of atrial pacing on arterial and coronary sinus endothelin-1 levels in syndrome X.

Syndrome X may be caused by a coronary microvascular dysfunction, possibly due to abnormalities in coronary endothelial function. Previous studies suggested that endothelin-1 (ET-1) might be involved in the pathogenesis of syndrome X. Baseline arterial and coronary sinus ET-1 levels were measured in 13 patients with syndrome X (10 women, 52+/-7 years) and in 8 control patients (5 women, 46+/-11 years). ET-1 was also measured after atrial pacing in 12 patients with syndrome X and all controls. To simultaneously assess the activity of nitric oxide, guanosine 3'-5'-cyclic monophosphate (cGMP) was also measured in 11 patients with syndrome X and 7 controls. Baseline arterial (2.27+/-0.46 vs. 1.90+/-0.22 pg/ml, p<0.05) and coronary sinus (2.03+/-0.43 vs. 1.68+/-0.28 pg/ml, p = 0.06) ET-1 plasma levels were higher in patients than in controls. After pacing, arterial ET-1 levels did not change in either group and coronary sinus ET-1 levels were also unchanged in controls. In contrast, coronary sinus ET-increased significantly in response to atrial pacing in patients with syndrome X (p = 0.023), and differences between coronary sinus ET-1 levels of patients with syndrome X and controls after pacing became highly significant (2.22+/-0.45 vs. 1.69+/-0.20 pg/ml, respectively, p = 0.006). No significant differences in arterial and coronary sinus cGMP concentrations were found between the 2 groups, both at baseline and after pacing. Our findings suggest that an increased vasoconstrictor activity of microvascular endothelium is present in at least some patients with syndrome X and may be involved in the pathogenesis of the syndrome.

Electromagnetic interference of digital and analog cellular telephones with implantable cardioverter defibrillators: in vitro and in vivo studies.

The present study examines the potential electromagnetic interference effects induced by cellular telephones on ICDs. We developed ad hoc protocols to conduct both in vitro and in vivo trials on most of the implantable cardioverter defibrillators available on the international market. Trials were conducted with three cellular telephones: two GSM (Global System for Mobile Communication) and one TACS (Total Access Communication System). A human trunk simulator was used to carry out in vitro observations on six ICDs from five manufacturers. In vivo tests were conducted on 13 informed patients with eight different ICD models. During the trials in air, GSM telephones induced interference effects on 4 out of the 6 cardioverter defibrillators tested. Specifically, pulse inhibition, reprogramming, false ventricular fibrillation, and ventricular tachycardia detections occurred, which would have entailed inappropriate therapy delivery had this been activated. Effects were circumscribed to the area closely surrounding the connectors. When the ICD was immersed in saline solution, no effects were observed. Three cases of just ventricular triggering with the interfering signal were observed in vivo.

Capture window in human atrial fibrillation: evidence of an excitable gap.

INTRODUCTION: Local capture of atrial fibrillation (AF) was shown in animal experiments for a wide range of pacing rates, thus demonstrating the existence of an excitable gap. The aim of this study was to assess the existence of an excitable gap in human AF by studying the mechanism of local control and acceleration of AF over a wide range of pacing rates and by evaluating the time window of capture. METHODS AND RESULTS: Recording and stimulation of electrical activity in the right atrium during AF was performed by a monophasic action potential (MAP) contact electrode catheter in 17 patients with lone AF during electrophysiologic study. Stimulation was started at pacing intervals close to the mean AF interval, and the time window of capture was estimated by lengthening or shortening the pacing interval until capture was lost. Pacing intervals shorter than the minimum cycle length for capture were also tested. Beat-to-beat measurements of AF intervals during pacing were performed. Atrial MAP signal showed rapid irregular activity with an average AF interval of 151.3 +/- 16.1 msec and SD of 21.3 +/- 5.2 msec. Rapid pacing with a cycle length slightly shorter or longer than the mean AF interval resulted in local capture of AF. The width of time window of capture ranged from 22 to 36 msec, with a mean value of 28.8 +/- 4.9 msec. The average minimum pacing interval of stable capture was 129.2 +/- 19.5 msec, while the maximum was 158.1 +/- 18.7 msec, corresponding to 85% and 104% of mean AF cycle length, respectively. Pacing too rapidly resulted in a transient acceleration of AF, with an average shortening of fibrillation interval from 149.8 +/- 16.6 to 123.2 +/- 15.1 msec (P < 0.01). CONCLUSION: Local capture is feasible during AF in humans over a wide range of pacing rates, indicating the possibility of regional control of the fibrillatory process. This result demonstrates the presence of an excitable gap during AF in human atria.

A typical pattern of activation in the right atrium during paroxysmal atrial fibrillation: the washing-machine phenomenon.

Atrial fibrillation affects a large population of patients. The electrophysiological mechanisms that initiate and maintain atrial fibrillation may be multiple. Even if some studies exploring right atrial activation have been recently published, data concerning atrial fibrillation activation patterns and its mechanisms are still scarce and controversial. This study supplies information on right atrial activation during atrial fibrillation. Twenty-four patients with recurrent, drug-refractory, lone paroxysmal atrial fibrillation underwent an extensive mapping of the right atrium. A pattern of organized atrial fibrillation (type 1) was noted in the trabeculated right atrium and atrial roof, characterized by discrete atrial electrograms, separated by an isoelectric baseline, with a continuous switching between clockwise and counterclockwise activation that we called washing-machine phenomenon. In the majority of patients, recordings from the anterior and medial areas of the atrial septum, showed fractionated electrograms consistent with a more disorganized activation pattern. Atrial activation in the inferior septum and coronary sinus was rather disorganized, neither synchronized with the activation sequence of the trabeculated right atrium nor with that of the anterior septum. Furthermore, the activation pattern showed fractionated electrograms and a variability of the isoelectric baseline similar to that recorded in the septum. No significant complications were reported during the procedure. In conclusion, mapping of the right atrium during induced atrial fibrillation shows a very typical pattern of activation in the trabeculated right atrium that we called the washing-machine phenomenon. Whether this sequence of activation represents a bystander situation or an active conditioning factor needs further investigations.

Which strategy is "best" after myocardial infarction? The Beta-blocker Strategy plus Implantable Cardioverter Defibrillator Trial: rationale and study design.

The Beta-blocker Strategy plus Implantable Cardioverter Defibrillator (BEST-ICD) Trial is a multicenter prospective randomized trial that started in June 1998, in 95 centers in Italy and Germany. The trial will test the hypothesis whether, in high-risk post myocardial infarction (MI) patients already treated with beta blockers, electrophysiologic study (EPS)-guided therapy (including the prophylactic implantation of implantable cardioverter defibrillator [ICD] in inducible patients) will improve survival compared with conventional therapy. Patients eligible for the study are survivors of recent MI (> or = 5 and < or = 21 days), aged < or = 80 years, with left ventricular ejection fraction < or = 35% and > or = 1 of the following additional risk factors: (1) ventricular premature beats > or = 10/hour; (2) decreased heart rate variability (standard deviation of unusual RR intervals < 70 msec); and (3) presence of ventricular late potentials. Furthermore, all enrolled patients must be able to tolerate at least 25 mg of metoprolol per day. These patients constitute about 9% of all patients with recent MI and are expected to have a 2-year all-cause mortality > 25% of which 50% is anticipated to be from sudden death. The main criteria of exclusion from the study are (1) a history of sustained ventricular arrhythmia; (2) documentation of nonsustained ventricular tachycardia during the screening phase; and (3) the need for myocardial revascularization and contraindications or intolerance to beta-blocker therapy. Eligible patients will be randomized to 2 different therapeutic strategies: conventional strategy or EPS/ICD strategy. Patients allocated to the EPS/ICD strategy will undergo further risk stratification, and electrophysiologically inducible patients (approximately 35%) will receive prophylactic ICDs, in addition to the conventional therapy, whereas noninducible patients will be only conventionally treated. The primary endpoint of the study will be death from all causes. By hypothesizing a 30% reduction in the 2-year mortality (from 20% to 14%) in the EPS/ICD group compared with conventionally treated patients, 1,200 patients will have to be included. A triangular, 2-sided sequential design with preset boundaries, for a 5% significance level and 90% power to detect a reduction in 2-year mortality from 20% to 14%, will be used to permit early termination of the trial if the strategy is found to be efficacious, no difference, or inefficacious.

Role of abnormal pain sensitivity and behavioral factors in determining chest pain in syndrome X.

OBJECTIVES: We sought to investigate whether patients with syndrome X have an abnormal perception of cardiac pain. BACKGROUND: Previous studies have reported an increased sensitivity to potentially painful cardiac stimuli in patients with syndrome X. However, it is not clear whether this increase is due to an increased perception of pain or to an enhanced tendency to complain. METHODS: We assessed cardiac sensitivity to pain in 16 patients with syndrome X and 15 control subjects by performing right atrial and ventricular pacing with increasing stimulus intensity (1 to 10 mA) at a rate 5 to 10 beats higher than the patient's heart rate. False and true pacing were performed in random sequence, with both patients and investigators having no knowledge of the type of stimulation being administered. RESULTS: No control subject had pacing-induced pain; conversely, 8 patients with syndrome X reported angina during atrial pacing (50%, p < 0.01) and 15 during ventricular pacing (94%, p < 0.001). During atrial stimulation, both true and false pacing caused chest pain in a similar proportion of patients (50% vs. 63%, p = 0.61), whereas during ventricular stimulation, true pacing caused chest pain in a higher proportion of patients (94% vs. 50%, p < 0.05). Pain threshold and severity of pain (1 to 10 scale) were similar during true and false atrial pacing, whereas true ventricular pacing resulted in a lower pain threshold (mean +/- SD 3.7 +/- 3.0 vs. 7.9 +/- 2.8 mA, p < 0.001) and a higher level of pain severity (7.3 +/- 2.7 vs. 3.1 +/- 3.5, p < 0.001) than did false pacing. CONCLUSIONS: Patients with syndrome X frequently reported chest pain even in the absence of cardiac stimulation. Yet, in addition to this increased tendency to complain, they also exhibited a selective enhancement of ventricular painful sensitivity to electrical stimulation.

[Idiopathic atrial fibrillation of recent onset and atrial stunning: the echocardiographic evidence after pharmacological cardioversion]. / Fibrillazione atriale idiopatica di recente insorgenza e stunning atriale: evidenza ecocardiografica dopo cardioversione farmacologica.

Successful cardioversion of atrial fibrillation may result in prolonged recovery of normal atrial mechanical function. This prolonged recovery of atrial contraction (so-called atrial stunning) might depend on: the amount of energy delivered during direct current cardioversion; the time course between the onset of atrial fibrillation and the conversion to sinus rhythm; the size of the left atrium; the underlying cardiac disease. The aim of this study was to evaluate, in subjects with normal atrial size and without heart disease, the phenomenon of atrial stunning soon after pharmacological cardioversion of an episode of atrial fibrillation of recent onset. Twenty-five patients with an acute episode of atrial fibrillation, without evidence of heart disease and M-mode left atrial dimension (< or = 40 mm received i.v. propafenone or flecainide 2 mg/kg/10 min in order to restore sinus rhythm. Atrial fibrillation lasted < 48 hours in all patients. Doppler echocardiography was used to assess atrial function, by recording the peak velocity of atrial contraction (A wave). An echocardiographic study was performed within 12 hours of successful cardioversion and was repeated on day 3, 12 and 30. The size of the left atrium (37 +/- 3.9; 37.57 +/- 2.9; 37.4 +/- 4; 37.82 +/- 3.7 mm) and peak E velocity (57.97 +/- 18.3; 59.4 +/- 18.3; 59.0 +/- 16; 59.07 +/- 16.7 cm/s) did not show any significant differences over the time, as demonstrated by the serial echocardiographic evaluations. In contrast, both peak A velocity (cm/s) and E/A ratio evaluated within 12 hours of cardioversion (60.29 +/- 12.3 and 1.0 +/- 0.37) and on day 3 (73.71 +/- 10.7 and 0.82 +/- 0.27) were statistically different (p < 0.000001 and p < 0.00001). No further statistically significant increase was found in subsequent examinations (respectively 76.31 +/- 12 and 0.78 +/- 0.24 on day 12, and 76.91 +/- 14.8 and 0.78 +/- 0.21 on day 30). In conclusion, this study suggests that patients with alone atrial fibrillation of recent onset have a delayed recovery of normal atrial systolic function even after pharmacological cardioversion.

Electrograms for identification of the atrial ablation site during catheter ablation of accessory pathways.

BACKGROUND: Catheter ablation of accessory pathways using radiofrequency current has been shown to be effective in patients with Wolff-Parkinson-White syndrome, by using either the ventricular or atrial approach. However, the unipolar electrogram criteria for identifying a successful ablation at the atrial site are not well established. METHODS AND RESULTS: One hundred patients with Wolff-Parkinson-White were treated by delivering radiofrequency energy at the atrial site. Attempts were considered successful when ablation (disappearance of the delta wave) occurred in < 10 seconds. In eight patients with concealed pathway, the accessory pathway location was obtained by measuring the shortest V-A interval either during ventricular pacing or spontaneous or induced reciprocating tachycardia. In 92 patients both atrioventricular valve annuli were mapped during sinus rhythm, in order to identify the accessory pathway (K) potential before starting the ablation procedure. When a stable filtered (30-250 Hz) "unipolar" electrogram was recorded, the following time intervals were measured: (1) from the onset of the atrial to the onset of the K potential (A-K); (2) from the onset of the delta wave to the onset of the K potential (delta-K); and (3) from the onset of the K potential to the onset of the ventricular deflection (K-V). During unsuccessful versus successful attempts, A-K (51 +/- 11 ms vs 28 +/- 8 ms, P < 0.0001 for left pathways [LPs]; and 44 +/- 8 ms vs 31 +/- 8 ms, P < 0.02 for right pathways [RPs]) and delta-K intervals (2 +/- 9 ms vs -18 +/- 10 ms, P < 0.0001 for LPs; and 13 +/- 7 ms vs 5 +/- 8 ms, P < 0.02 ms for RPs) were significantly longer. CONCLUSIONS: Short A-K interval (< 40 ms), and a negative delta-K interval recorded from the catheter positioned in the atrium are strong predictors of successful ablation of LPs and RPs. Therefore, the identification of the K potential appears to be of paramount importance for positioning of the ablation catheter, followed by analysis of A-K and delta-K unipolar electrogram intervals. However, it appears that the mere recording of K potential is not, per se, predictive of successful outcome, but rather the A-K and delta-K interval.

[Transcatheter radiofrequency ablation in supraventricular tachycardia in children: immediate results and mid-term follow-up]. / Ablazione transcatetere con radiofrequenza delle tachicardie sopraventricolari in età pediatrica: risultati immediati e di un follow-up a medio termine.

OBJECTIVES: The purpose of this study was to evaluate the efficacy and safety of radiofrequency ablation of supraventricular tachycardias due to a reentry circuit in a group of closely followed-up pediatric patients. PATIENTS: Forty-six pediatric patients (mean age 12.6 years, range 3-18) underwent a total of 48 radiofrequency ablation procedures for reciprocating supraventricular tachycardia. Thirty-nine had an orthodromic reentry tachycardia, 6 an atrioventricular node reentry tachycardia and 1 a permanent junctional reciprocating tachycardia. METHODS: To ablate the overt accessory pathways, the Kent potential (K) was identified and then the shortest A-K, and delta wave-K intervals were measured. The shortest V-A interval was identified for those concealed. For the left-sided accessory pathways, we used the retrograde transaortic approach in 10 procedures and the transseptal approach in 18. Atrioventricular node reentry tachycardia was ablated at the site where the slow-pathway electrogram was recorded. Follow-up clinical data, electrocardiogram, 24-hours Holter monitoring and transesophageal atrial stimulation were obtained and evaluated. RESULTS: Early: We performed a total of 48 procedures. Among 41 procedures performed in the 39 patients with accessory pathway, 38 were successful (92,6%). Mean fluoroscopy time was 31 +/- 18 min. For left sided accessory pathways, mean fluoroscopy time of procedures with retrograde approach was 45 +/- 10 min and with transseptal 23 +/- 12 min (p < 0.01). Ablation of slow-pathway in patients with intranodal reentry tachycardia was successful in 3/6 cases (50%). The patient with permanent junctional reciprocating tachycardia was successfully ablated. Late: All patients are alive and none was lost during the follow-up after a mean time of 12.9 months (range 5-33). Success at last follow-up was 100% in patients with an accessory pathway and 33% in patients with atrioventricular node reentry. In patient with permanent junctional reciprocating tachycardia, the arrhythmia appeared again one month after the procedure, thus a second successful attempt was performed. COMPLICATIONS: Major complications (6,5%) including a right femoral vein thrombosis (one patient), an hematoma without pulse loss (one patient) and a non-sustained monomorphic ventricular tachycardia (one patient). CONCLUSIONS: Our data show high efficacy of radiofrequency ablation in pediatric patients with accessory pathways. The risks are low at follow-up evaluation, but might be helpful a longer-term follow-up in order to evaluate the risk of a long fluoroscopy time and the arrhythmogenic effect of the scar.

Catheter ablation of left accessory atrioventricular connections: the transseptal approach.

BACKGROUND: In the past few years, there has been a relative explosion of activity in the realm of interventional cardiology. The high rate of success of radiofrequency energy ablation have transformed catheter ablation from an investigational procedure into the first-line therapy for symptomatic Wolff-Parkinson-White syndrome. Radiofrequency catheter ablation for preexcitation syndrome is commonly based on a ventricular approach. Such an approach might be associated with the risk of prolonged arterial catheter manipulation, retrograde left ventricular catheterization, and production of multiple, potentially arrhythmogenic, ventricular lesions created during ablation. Potential risks can be avoided using atrial insertion ablation procedures. The transseptal procedure that was developed in the 1950s and 1960s as a diagnostic procedure and then shelved in the 1970s and early 1980s has now come back into prominence as a therapeutic technique in the treatment of valvular heart disease, and then in the ablation of the left accessory atrioventricular connections. METHODS: Atrial aspect of mitral annulus is a relatively smooth, nonobstructed surface that simplifies catheter movement, thereby permitting rapid and accurate accessory pathway location. Although primary use of earliest endocardial retrograde atrial activation as a marker of accessory pathway atrial insertion is sufficiently accurate to permit successful ablation, direct recording of an accessory pathway potential is an important predictor of successful ablation site. Moreover, the analysis of the unipolar atrial electrogram, recorded during sinus rhythm from the tip of the ablation catheter, provides further information for localizing the atrial insertion of the accessory pathways. Shortest atrial-accessory pathway and negative delta-accessory pathway intervals have been found to be the best predictors of the successful site. RESULTS: A 90.5% success of the transseptal approach on an overall population of 328 patients, higher for overt than for concealed pathways, is comparable with the results of the retrograde. Complications are 0.5%. CONCLUSION: In conclusion, the transseptal approach for ablation at the atrial site is very safe and highly effective, and avoids prolonged arterial cannulation and catheter manipulation in the ascending aorta and left ventricle.

[Results of surgical treatment in supraventricular tachycardias]. / Risultati del trattamento chirurgico delle tachicardie sopraventricolari.

From May 1989 to May 1992, 44 patients (mean age 41 years, range 15-66) underwent surgery for supraventricular tachycardias: in 35 patients with atrioventricular reentrant tachycardia or atrial fibrillation associated with accessory pathway and refractory to medical treatment, the epicardial approach was used; in 8 with atrioventricular nodal reentrant tachycardia, a perinodal cryosurgery of the atrioventricular node was used, and in 1 patient with atrial flutter a cryosurgical ablation around the orifice of the coronary sinus and surrounding tissues was performed. All 38 accessory pathways were successfully ablated in 35 patients and no recurrences of delta wave or tachycardia were observed during a mean follow-up of 17 +/- 10 months. Atrial perforation during surgery and pericarditis were the only complications observed. All 8 patients with atrioventricular nodal reentrant tachycardia were successfully treated: in 2 patients dual pathways persisted after surgery but tachycardia was no longer inducible. No recurrences were observed during a mean follow-up of 15 +/- 4 months. Since surgery (15 months), the patient with atrial flutter has been free of recurrent episodes of atrial flutter. In conclusion, surgical treatment of supraventricular tachycardias is highly successful, with no mortality and very low morbidity. Should transcatheter ablation fail, surgery should be the treatment of choice in patients with frequent and symptomatic supraventricular tachycardias.

Effects of acute and prolonged administration of propafenone on internal defibrillation in the pig.

Some antiarrhythmic sodium channel blocking drugs have been found to increase the energy necessary for internal defibrillation. Propafenone is a new drug that has been shown to be efficacious in the therapy of supraventricular and ventricular arrhythmias, and is of potential use in patients with defibrillators. The effects of short-term and prolonged propafenone administration on the internal defibrillation threshold (DFT) were determined in 43 pigs randomized to one of four groups: saline infusion (n = 10); propafenone infusion (n = 10); placebo administration for 8 days (n = 10); or propafenone administration for 8 days (n = 13). Two mesh electrodes were sutured on the right lateral and left lateral epicardial surface and current was delivered from the right electrode to the left electrode. Triplicate DFTs were obtained before and at 40 and 80 minutes after infusion of drug or placebo. In pigs receiving long-term administration, after baseline DFTs were obtained the electrodes were removed and the chest was closed. Following 8 days of drug or placebo administration, DFTs were redetermined. No changes were observed in the short- or long-term control groups. DFTs were lower after propafenone administration: either short-term infusion (20 +/- 6.2 joules at baseline; 15.6 +/- 5 joules at 40 minutes, p less than 0.05; 10.2 +/- 6 joules at 80 minutes, p less than 0.001) or long-term administration (17.8 +/- 2.6 joules at baseline versus 12 +/- 3.2 joules on drug, p less than 0.002). Decreased ventricular cycle lengths were found with acute administration of propafenone. Three pigs died during long-term administration of propafenone.(ABSTRACT TRUNCATED AT 250 WORDS)