Management of syncope referred urgently to general hospitals with and without syncope units.

OBJECTIVE: We tested the hypothesis that management of patients with syncope admitted urgently to a general hospital may be influenced by the presence of an in-hospital structured syncope unit. BACKGROUND: The management of syncope is not standardized. Methods We compared six hospitals equipped with a syncope unit organized inside the department of cardiology with six matched hospitals without such facilities. The study enroled all consecutive patients referred to the emergency room from 5 November 2001 to 7 December 2001 who were affected by transient loss of consciousness as their principal symptom. RESULTS: There were 279 patients in the syncope unit hospitals and 274 in the control hospitals. In the study group, 30 (11%) patients were referred to the syncope unit for evaluation. In the study group, 12% fewer patients were hospitalized (43 vs 49%, not significant) and 8% fewer tests were performed (3.3+/-2.2 vs 3.6+/-2.2 per patient, not significant). In particular, the study group patients underwent fewer basic laboratory tests (75 vs 86%, P=0.002), fewer brain-imaging examinations (17 vs 24%, P=0.05), fewer echocardiograms (11 vs 16%, P=0.04), more carotid sinus massage (13 vs 8%, P=0.03) and more tilt testing (8 vs 1%, P=0.000). In the study group, there was a +56% rate of final diagnosis of neurally mediated syncope (56 vs 36%, P=0.000). CONCLUSION: Although only a minority of patients admitted as an emergency are referred to the syncope unit, overall management is substantially affected. It is speculated that the use of a standardized approach, such as that typically adopted in the syncope unit, is able to influence overall practice in the hospital.

Success of serial external electrical cardioversion of persistent atrial fibrillation in maintaining sinus rhythm; a randomized study.

AIMS: The aim of this prospective, randomized study was to determine the efficacy of a serial external electrical cardioversion strategy in maintaining sinus rhythm after 12 months in patients with recurrent persistent atrial fibrillation. METHODS AND RESULTS: Ninety patients with persistent atrial fibrillation lasting more than 72 h but less than 1 year were randomized in a one to one fashion to repetition of up to two electrical cardioversions in the event of relapse of atrial fibrillation detected within 1 month of the previous electrical cardioversion (Group AGG), or to non-treatment of atrial fibrillation relapse (Group CTL). ECGs were scheduled at 6 h, 7 days, and 1 month. Clinical examination and ECGs were repeated during the 6-month and 12-month follow-up examinations. Echocardiography was repeated during the 6-month follow-up examination. Clinical and echocardiographic characteristics were similar in the two groups. All patients were treated with antiarrhythmic drugs before electrical cardioversion and throughout follow-up. After 12 months, sinus rhythm was maintained in 53% of Group AGG patients and in 29% of Group CTL patients (P<0.03). After 6 months, left ventricular ejection fraction had recovered significantly only in Group AGG (56.8 +/- 9.0% at enrollment vs 60.4 +/- 9.4% at 6 months,P <0.001). CONCLUSION: These results demonstrate that an aggressive policy towards persistent atrial fibrillation by means of repetition of electrical cardioversion after early atrial fibrillation recurrence is useful in maintaining sinus rhythm after 12 months.

The duration of atrial fibrillation influences the long-term efficacy of low-energy internal cardioversion.

BACKGROUND: It is commonly held that long-lasting atrial fibrillation (AF), especially if associated with marked enlargement of the left atrium, is a negative predictive factor for both the recovery and the maintenance of sinus rhythm. The aim of the present study was to identify the clinical features of patients who have a greater likelihood of success both in the acute phase and, especially, in the medium-long term. METHODS: Since June 1997, we have performed low-energy internal cardioversion to 93 patients (66 males, 27 females, mean age 62 +/- 9 years, range 26-80 years) with a mean duration of AF of 922 +/- 1032 days. Seventy-four patients had heart disease and 19 isolated AF. External cardioversion had been previously performed in 79 patients to no avail. All patients underwent antiarrhythmic therapy and were followed for a period of 13 +/- 7 months. RESULTS: Low-energy internal cardioversion proved efficacious, restoring sinus rhythm, in 92% of patients (86/93) and inefficacious in 8% (7/93). In 24% (21/86) the procedure, although efficacious, was followed by early recurrence of AF which proved to be intractable in 52% (11/21). At the end of the session, 81% (75/93) of the patients maintained sinus rhythm. At the end of follow-up, 40% (38/93) maintained sinus rhythm. Of all the parameters considered in the two groups, the duration of AF was the only one which differed significantly between the group in sinus rhythm and that in AF, with regard to both the efficacy of the procedure in the acute phase (755 +/- 868 vs 1618 +/- 1359 days, p < 0.001) and the long-term outcome (655 +/- 5.8 vs 1107 +/- 1098 days, p < 0.05). CONCLUSIONS: AF lasting more than 2 years constitutes a negative predictive factor for both the recovery and the long-term maintenance of sinus rhythm.

[Heart arrest]. / L'arresto cardiaco.

Cardiac arrest is one of the leading causes of mortality in industrialized countries and is mainly due to ischemic heart disease. According to ISTAT estimates, approximately 45,000 sudden deaths occur annually in Italy whereas according to the World Health Organization, its incidence is 1 per 1000 persons. The most common cause of cardiac arrest is ventricular fibrillation due to an acute ischemic episode. During acute ischemia the onset of a ventricular tachyarrhythmia is sudden, unpredictable and often irreversible and lethal. Each minute that passes, the probability that the patient survives decreases by 10%. For this reason, the first 10 min are considered to be priceless for an efficacious first aid. The possibility of survival depends on the presence of witnesses, on the heart rhythm and on the resolution of the arrhythmia. In the majority of cases, the latter is possible by means of electrical defibrillation followed by the reestablishment of systolic function. An increase in equipment alone does not suffice for efficacious handling of cardiac arrest occurring outside the hospital premises. Above all, an adequate intervention strategy is required. Ambulance personnel must be well trained and capable of intervening rapidly, possibly within the first 5 min. The key to success lies in the diffusion and proper use of defibrillators. The availability of new generation instruments, the external automatic defibrillators, encourages their widespread use. On the territory, these emergencies are the responsibility of the 118 organization based, according to the characteristics specific to each country, on the regulated coordination between the operative command, the crews and the first-aid means. Strategies for the handling of these emergencies within hospitals have been proposed by the Conference of Bethesda and tend to guarantee an efficacious resuscitation with a maximum latency of 2 min between cardiac arrest and the first electric shock. The diffusion of external automatic defibrillators is a preventive measure. Such equipment has permitted early defibrillation by non-medical first-aid personnel. These instruments contain software capable of recognizing an arrhythmia which may be defibrillated and of instructing the operator whether and when to press the defibrillation button. The latest instruments deliver the shock by means of a biphasic wave necessitating a lesser amount of energy which can be provided by lighter condensers. Thus such equipment weighs just a couple of kilograms. As suggested by ILCOR, for reasons of priority, such instruments should not only be available within hospitals and in ambulances but also on the territory, in particular in more crowded places. The availability of external automatic defibrillators in such places should reduce the time latency before intervention and thus increase survival. The ILCOR guidelines have suggested the constitution of an itinerary team well equipped for defibrillation and composed of trained personnel of State Institutions such as the Municipal Police, Traffic Police and the Fire Brigades. With regard to the majority of arrhythmias amenable to defibrillation which occur at home or in less crowded places, other strategies, such as primary prevention and training programs for categories at increased risk, must be employed. Antiarrhythmic drugs have long been considered the best solution for the prevention and treatment of ventricular tachyarrhythmias. However, the approach to these pathologies has drastically changed during the last few years owing to accumulating evidence in favor of defibrillators which may be implanted for the primary and secondary prevention of malignant ventricular arrhythmias. For patients with previous cardiac arrest, randomized studies have proven the advantages of such an approach compared to medical therapy. On the basis of the above, the guidelines for the use of antiarrhythmic implants have been modified. In most western countries, the laws regarding this aspect of medicine have recently been renewed. In the United States, where there is the "Law of the Good Samaritan", in order to protect and acquit persons who give first-aid, many states have adopted new laws which promote the use of external automatic defibrillators. Following recent dispositions by the President of the United States that defibrillators should be present in all Federal properties and on civil aircraft, a new Federal Law is about to pass. Italy lacks legislation regarding the use of defibrillators: in order to rectify this position, which is still anchored to existing dispositions of the civil and penal codes including those regarding the omission of first-aid, a bill entitled "The definition and modalities of the use of the external cardiac defibrillator" has recently been presented.

Pacemapping of the triangle of Koch: a simple method to reduce the risk of atrioventricular block during radiofrequency ablation of atrioventricular node reentrant tachycardia.

Slow pathway ablation in common AVNRT can be complicated by total AV block. When radiofrequency energy is delivered to the posterior aspect of the triangle of Koch, total AV block may be the consequence of the absence of anterograde conduction along the fast pathway or of inadvertent damage to a fast pathway abnormally located close to the slow pathway. To localize the anterogradely conducting fast pathway, the triangle of Koch was pacemapped in 72 patients who underwent the ablation of common AVNRT. In all cases, before ablation the St-H interval was calculated by stimulating the anteroseptal (AS), mid-septal (MS), and posteroseptal (PS) aspect of the triangle of Koch at a rate slightly faster than the sinus rate. In all patients, common AVNRT was induced. In 64 (89%) of 72 patients (group A) the shortest St-H interval was recorded on stimulating the AS region. In six (8%) patients (group B) the shortest St-H interval was recorded on stimulating the MS region. Finally, in two (3%) patients (group C) the shortest St-H interval was recorded stimulating in the PS region. In group C, AH interval, calculated on stimulating in the AS region, was significantly longer than in patients of groups A and B (200 +/- 99 ms vs 64 +/- 18 and 62 +/- 3, respectively). In group A, on stimulating in the AS, MS, and PS regions, the AH interval remained constant in all patients. In contrast, in groups B and C on stimulation in the MS and PS regions, AH interval shortened (in group B from 56 +/- 8 to 27 +/- 37 and 37 +/- 14, respectively; in group C from 200 +/- 99 to 170 +/- 100 and to 137 +/- 109, respectively). In groups A and B, a posteroseptal slow pathway, and in group C, an anteroseptal retrograde fast pathway were successfully ablated without AV block. Pacemapping of the triangle of Koch can help to recognize patients in whom the anterograde conducting fast pathway is abnormally located far from the anteroseptal region or in whom anterograde conduction of the fast pathway is absent. In these cases the risk of AV block can be reduced by performing slow pathway ablation in a site sufficiently far from the site of the anterograde fast pathway or ablating the retrogradely conducting fast pathway.

Long-term follow-up after atrioventricular nodal ablation and pacing: low incidence of sudden cardiac death.

Sudden cardiac death (SCD) has been reported in patients with drug refractory AF who underwent AV nodal ablation and pacing. However, whether SCD in these patients is related to the underlying heart disease or to the ablating and pacing procedure remains uncertain. Between May 1987 and January 1997, AV nodal ablation was performed in 585 patients (mean age 66 +/- 11 years) with drug-resistant, paroxysmal (n = 308) or chronic (n = 277) AF in 12 Italian centers. Lone AF was present in 133 patients. After AV junction ablation, patients underwent VVIR (454 patients) or DDDR (131 patients) pacemaker implantation. At a follow-up of 33.6 +/- 24.2 months, 80 (13.7%) deaths were recorded: 40 noncardiac, 23 nonsudden, and 17 sudden cardiac death (3%, 1.04% per year). Among five variables, including age. NYHA functional class, presence of heart disease, paroxysmal or chronic AF, previous embolic events, and LVEF, the presence of heart disease (P = 0.007) and a LVEF < 0.45, (P = 0.003) were associated with a higher risk of SCD. Analysis of SCD-free survival by log-rank test showed a higher incidence of SCD in patients with LVEF < 0.45 (P = 0.0001) and with coronary artery disease (P = 0.005). In this large cohort, a low incidence of long-term SCD after AV nodal ablation and pacing for drug-refractory AF was observed. The presence of underlying heart disease and the extent of baseline LV dysfunction were associated with an increased likelihood of SCD.

Thromboembolism after atrioventricular node ablation and pacing: long term follow up.

OBJECTIVE: To assess the incidence of arterial embolic events in patients with high rate, drug resistant, severely symptomatic paroxysmal and chronic atrial fibrillation who have undergone atrioventricular (AV) node ablation and permanent pacing. DESIGN: Multicentre retrospective cohort study. PATIENTS AND MANAGEMENT: From May 1987 to January 1997, AV node ablation was performed in 585 severely symptomatic patients (mean (SD) age 66 (11) years) with high rate, drug resistant paroxysmal atrial fibrillation (308) or chronic atrial fibrillation (277). Lone atrial fibrillation was present in 133 patients, while the remaining 452 suffered from dilated, ischaemic, or valvar heart disease. Patients underwent VVIR (454) or DDDR (131) pacemaker implantation, after AV node ablation. Antiplatelet agents were given to 202 patients, warfarin to 187 patients. RESULTS: During a follow up of 33.6 (24.2) months, thromboembolic events were observed in 17 patients (3%); the actuarial occurrence rates of thromboembolism were 1.1%, 3%, 4.2%, and 7.4% after one, three, five, and seven years, respectively. Among five variables, univariate analysis showed that only the presence of chronic atrial fibrillation at the time of ablation (relative risk (RR) = 1.8, 95% confidence interval (CI) = 1.02 to 3. 20, p = 0.04) and the need for warfarin treatment (RR = 1.6, 95% CI 1.00 to 2.71, p = 0.048) were associated with a significantly higher risk of occurrence of thromboembolic events. On multivariate analysis the only predictor of embolic events during the follow up was the presence of chronic atrial fibrillation. CONCLUSIONS: Data from this large cohort of patients indicate a fairly low incidence (1.04% per year) of thromboembolic events after AV node ablation and pacing for drug refractory, high rate atrial fibrillation.

Modification of antegrade slow pathway is not crucial for successful catheter ablation of common atrioventricular nodal reentrant tachycardia.

We tested the hypothesis that in some patients affected by typical AVNRT, successful catheter ablation treatment may be achieved independently of specific measurable electrophysiological modifications of antegrade AV node conducting properties. Standard electrophysiological parameters and comparable antegrade AV node function curves were obtained, before and after successful ablation, in 104 patients (mean age 52 +/- 16 years; 69 women and 35 men) affected by the common form of AVNRT. The end point of the ablation procedure was noninducibility of AVNRT and of no more than one echo beat. For the purpose of this study, AV node duality was defined as an increase of > or = 50 ms in the A2H2 interval in response to a 10 ms decrease of the A1A2 coupling interval. Before ablation, AV node duality was present in 65 patients (62%) and absent in 39 patients (37%). Ablation caused measurable modifications of electrophysiological properties of the AV node in most patients with elicited AV node duality, but not in most patients without demonstrable AV node duality. After ablation, AV node duality persisted in 20 patients who had it before, whereas a new duality that could not be elicited before appeared in 5 patients. During 19 +/- 6 months of follow-up, clinical AVNRT recurred in 1 of 45 patients who had disappearance of AV node duality after ablation, in 1 of 34 patients who did not show AV node duality before and after ablation, and in 1 of 20 patients who had persistence of AV node duality after ablation. In conclusion, modifications of antegrade conduction properties of the AV node are not crucial for the cure of AVNRT in many patients.

[Doppler tissue imaging: a new method in the study of diastolic function in left ventricular hypertrophy]. / Il Doppler tissue imaging, nuova metodica di studio della funzione diastolica nell'ipertrofia del ventricolo sinistro.

BACKGROUND: Many factors influence diastolic function indexes obtained by monitoring left ventricular filling. Recent reports suggest that the study of myocardial wall velocity with Doppler tissue imaging (DTI) can give diastolic function parameters that are less affected by the same factors. An altered diastolic function has been demonstrated with invasive methods in patients with left ventricular hypertrophy (LVH). The aims of this study were 1) to compare a group of healthy subjects with a group of patients with LVH and presumably affected by diastolic dysfunction, to try to demonstrate if DTI could give new indexes to discriminate between the two groups; 2) to compare the indexes obtained with DTI against the ones given by Doppler study of left ventricular filling in the two populations. MATERIALS AND METHODS: Forty-two patients with LVH were compared to forty normal subjects. We studied the posterior wall velocity with pulsed DTI from parasternal view, measuring the early diastolic velocity (E'), the late diastolic velocity (A') and the E'/A' ratio. In addition, we estimated the usual ventricular filling parameters and the time interval between R wave of ECG and the peaks of E' and E waves. RESULTS: At left ventricular filling, patients with LVH showed an increase in A-wave peak velocity (mean 75.3 cm/s versus 66.4 cm/s; p < 0.05) and prolonged deceleration time (mean 216 ms versus 181 ms; p < 0.05), as compared to normal reference subjects. E-wave peak velocity and E/A ratio did not differ between the two groups. At DTI, patients with LVH had decreased early diastolic velocity (E') (mean 9 cm/s versus 12 cm/s; p < 0.05) and E'/A' ratio (mean 1.53 versus 1.91; p < 0.05) as compared to the control group. We observed an inverse correlation between E' wave and age in normal subjects. There was no correlation between the early diastolic myocardial velocity (E') and early inflow velocity (E) in both groups. A correlation was found between A and A' waves in normal subjects, but not in hypertrophic ones. The E'-wave peak always preceded the E-wave peak in all the subjects. CONCLUSION: Diastolic function indexes achieved by DTI can offer additional information that is independent of the data derived from left ventricular filling.

[Doppler tissue imaging in the study of the diastolic function in amyloidosis cardiopathy]. / Il Doppler tissue imaging nello studio della funzione diastolica nella cardiopatia amiloidosica.

Doppler tissue imaging (DTI) is an adaptation of the color-doppler, which allows the measurement of low-speed myocardial wall movement. We describe the case of a 51-year-old woman suffering from cardiac amyloidosis with serious endangerment of the diastolic function and mitral flow velocity pattern that was indistinguishable from the normal. The protodiastolic speed of the myocardial walls was measured with pulsed DTI, which was used as a diastolic function index. In this patient, the speed was 5 cm/sec, which was markedly lower than the values found in normal subjects and published recently. Moreover, the DTI M-mode images are examined here in order to point out different characteristics compared to the ones that can be obtained in normal subjects. This therefore exemplifies the possible use of this new technique in studying diastolic function.

Multiple mechanisms of successful slow-pathway catheter ablation of common atrioventricular nodal re-entrant tachycardia.

BACKGROUND: In patients with atrioventricular nodal re-entrant tachycardia, modifications of the antegrade atrioventricular nodal function curve caused by catheter ablation of the so-called slow pathway are heterogeneous, but have not yet been systematically evaluated. AIM: To test the hypothesis that successful treatment is independent of specific electrophysiological modifications of atrioventricular nodal conducting properties. METHOD: Standard electrophysiological parameters and comparable antegrade atrioventricular nodal function curves were obtained, before and after successful ablation, in 104 patients (mean age 52 +/- 16 years: 69 women) affected by the common form of atrioventricular nodal re-entrant tachycardia. RESULTS: Three different major patterns of antegrade atrioventricular nodal function curve were caused by ablation: downward shift of the curve with disappearance of atrioventricular nodal duality, suggesting the elimination of the slow pathway in 54 (52%) patients (type 1): absence of clear modifications of the curve (and of slow pathway ablation) in 33 (32%) patients (type 2); upward shift of the curve, suggesting a further slowing of conduction velocity through the slow pathway in 17 (16%) patients (type 3). Type-1 pattern was more frequent in patients < or = 45 years, whereas type-2 pattern was more frequent in those > 45 years. CONCLUSION: Successful ablation of atrioventricular nodal re-entrant tachycardia is independent of specific modifications of antegrade atrioventricular conduction and probably depends on critical nodal and perinodal tissue damage at different sites on the re-entrant circuit. The effects of ablation are influenced by patient age.

Clinical usefulness of slow pathway ablation in patients with both paroxysmal atrioventricular nodal reentrant tachycardia and atrial fibrillation.

Some patients with atrioventricular (AV) node reentrant tachycardia (AVN RT) also presented with atrial fibrillation (AF). In this study we demonstrate that slow pathway ablation is able to suppress both AVN RT and AF in subjects without structural heart abnormalities, whereas in patients with structural heart abnormalities after ablation AF frequently recurs.

Evaluation of atrial vulnerability with transoesophageal stimulation in patients with atrioventricular junctional reentrant tachycardia. Comparison with patients with ventricular pre-excitation and with normal subjects.

The aim of our work was to evaluate the inducibility of atrial fibrillation in a group of patients with atrioventricular junctional reentrant tachycardia and to compare it with that of patients with a Kent-type ventricular pre-excitation (Wolff-Parkinson-White syndrome) and a control group. One hundred and twenty-five subjects were separated into groups. Group 1 comprised 49 Wolff-Parkinson-White patients, with a mean age of 26.4, range 10-66 years; group 2, 51 patients with atrioventricular junctional reentrant tachycardia inducible by transoesophageal atrial stimulation and/or clinically documented, with a mean age of 43.4, range 16-78 years; group 3, 25 control subjects with a mean age of 26.4, range 13-76 years. Each subject underwent atrial transoesophageal stimulation with the following protocol: programmed atrial stimulation with 1 and 2 stimuli during atrial pacing of 100.min-1 and 150.min-1; atrial stimulation for 10 s at a rate of 200-300-400-500-600.min-1 with intervals of 10 s between stimulations, five successive 'ramp-up' atrial stimulations for 9 s with the rate increasing from 100 to 800.min-1 with intervals of 10 s between stimulations. The end point was the completion of the protocol or induction of sustained atrial fibrillation (> 1 min). The chi-square test was used for statistical analysis. Our results showed that in group 1 atrial fibrillation was induced in 27/49 patients (55.1%); this was sustained in 13/49 (26.5%) and non-sustained in 14/49 (28.5%); in group 2, atrial fibrillation was induced in 22/51 patients (43.0%); it was sustained in 7/51 (13.7%) and non-sustained in 15/51 (29.4%); in group 3, sustained atrial fibrillation was not induced in any subject and in only one subject was a non-sustained atrial fibrillation (4 s) induced. The chi-square test showed that group 2 vs group 1 were non-significant, while group 2 vs group 3 and group 1 vs group 3 were significant (P < 0.003 and P < 0.0007, respectively). Therefore group 2 patients showed a greater atrial vulnerability in comparison to the control subjects and a similar vulnerability to group 1 patients. It is possible that the greater atrial vulnerability in the patients of group 2 was due to the double nodal pathway.

Successful catheter ablation by radiofrequency energy of posteroseptal accessory pathway in a patient with drug refractory Wolff-Parkinson-White syndrome.

A 45-year-old patient with the Wolff-Parkinson-White syndrome suffering from recurrent intractable reciprocating atrioventricular tachycardia (RAVT) is reported. He used amiodarone, sotalol, quinidine, propafenone and flecainide unsuccessfully. An electrophysiological study (EPS) performed with four catheters localized the site of the anomalous pathway in the ostium of the coronary sinus. In this region we could also record a Kent potential. In the ostium of the coronary sinus, radiofrequency energy was repeatedly applied until the conduction over the accessory pathway was abolished both in the anterograde and the retrograde direction. The Kent deflection detectable before ablation, could not be detected after it. During follow-up (1 month) the patient remained asymptomatic and the control EPS showed no evidence of pre-excitation, either anterogradely or retrogradely.

[The endocavitary and transesophageal electrophysiological findings in idiopathic atrial fibrillation]. / Rilievi elettrofisiologici endocavitari e transesofagei nella fibrillazione atriale idiopatica.

BACKGROUND: We studied 105 patients (pts) in order to help clarify the pathogenetic mechanisms of idiopathic atrial fibrillation (AF). Eighty of these pts (Group I) had experienced paroxysmal AF, and 25 were normal control subjects (Group II). Twenty-two pts out of Group I had idiopathic paroxysmal AF (Group IA), while the remaining 58 (Group IB) presented with a heart disease or a WPW pattern. METHODS: All pts underwent endocavitary (EEPS) (69) or transesophageal (TEPS) (36) electrophysiologic study. In all pts the inducibility of a sustained AF (greater than 1 min) was tested by aggressive stimulation protocols including high frequency atrial bursts. RESULTS: In Group I a sustained AF was induced in 82% of cases vs 4% of Group II cases (p less than 0.001). In Group I there was no difference between pts with or without idiopathic AF (IA 73% vs IB 86%, NS). In two pts with idiopathic AF a concealed Kent bundle was identified and a reciprocating atrioventricular tachycardia was induced, which in one case spontaneously degenerated into AF. Four athletes with idiopathic AF were studied before and after autonomic blockade. AF was induced in all during the basal state, lasting several hours, and after autonomic blockade in 3 pts, lasting again for several hours. In 1 patient (pt) the arrhythmia spontaneously resolved within 50 sec. CONCLUSIONS: 1) The induction of a sustained AF by EEPS or TEPS is a pathologic phenomenon which is frequently observed in pts with clinical episodes of paroxysmal AF, while it is very rare in normal control subjects. 2) Pts with idiopathic AF have an electrophysiologic behaviour similar to pts with non-idiopathic AF. This fact suggests that among the former, most cases probably have a concealed atrial anomaly. In some cases this atrial anomaly can be related to the existence of a Kent bundle. 3) In athletes with paroxysmal AF the inducibility of a sustained AF both in the basal state and after autonomic blockade suggests that the vagal prevalence typical of such subjects probably plays a secondary role.

[Electrophysiological mechanisms of atrial tachyarrhythmia]. / I meccanismi elettrofisiologici delle tachiaritmie atriali.

Both supraventricular and ventricular arrhythmias are generated by one of the following 2 mechanisms: increased automaticity and reentry. In this paper we will refer about the mechanisms of the commonest atrial tachyarrhythmias. Atrial parasystole: it is determined by an automatic focus protected by entrance block. In some cases the focus is only partially protected owing to a partial block or to the electrotonic influence of the sinus rhythm. Atrial tachycardia: it can be due both to increased automaticity and to reentry. Atrial flutter: it is generated by a counterclockwise macroreentry localized in the right atrium. The left atrium is passively activated. A critical delay of the circuit is present near the ostium of the coronary sinus. The lesion of this area by surgery or catheter ablation can interrupt and prevent the arrhythmia. Atrial fibrillation: it is generated by multiple wavelets which continuously change site and direction. The functional multiple reentry is made possible by dispersion of atrial refractoriness and by the existence of areas having delayed conduction. It is noteworthy that the same arrhythmia and the same atrial electrophysiologic alterations are present in many clinical conditions having very different anatomic backgrounds: subjects with no evident heart disease and normal atria, subjects with large atria, subjects with an anomalous pathway. These data suggest that some important informations are probably lacking about the genesis of this arrhythmia.

[The Wolff-Parkinson-White syndrome at risk]. / La sindrome di Wolff-Parkinson-White a rischio.

Wolff-Parkinson-White (WPW) syndrome is characterized by a wide spectrum of clinical conditions: many subjects remain symptom free during the whole life, others suffer from paroxysmal episodes of reciprocating atrioventricular tachycardia, a minority of patients present with episodes of atrial fibrillation. The latter is the most dreadful arrhythmia because in the presence of a short refractory period of the Kent bundle it can produce very high ventricular rates, degenerate into ventricular fibrillation and cause sudden death. Sudden death however is very rare in the WPW syndrome. In 1988 the European registry on "sudden death in the WPW syndrome" collected 26 cases of various centres. This study demonstrated that sudden death occurs in 73% of cases in symptomatic subjects while in the remaining 27% it is an unexpected event in previously asymptomatic subjects. While sudden death is very rare, high frequency atrial fibrillation producing hemodynamic deterioration is not so rare, although its precise incidence is unknown. In hospitalized WPW patients it is reported in 10-30% of cases. One of the main problems in symptomatic and asymptomatic patients with the WPW pattern is to identify the subjects at risk of high frequency arrhythmias. Many Authors suggested that endocavitary or transesophageal electrophysiologic study can be useful in this regard if its results are evaluated by a multiparametric approach. In our opinion the main parameters to be evaluated are: presence or absence of retrograde conduction of the Kent bundle (which is necessary for the initiation of atrioventricular reciprocating tachycardia which is the commonest trigger of atrial fibrillation); atrial vulnerability; shortest and mean RR intervals during induced atrial fibrillation.(ABSTRACT TRUNCATED AT 250 WORDS)