Dynamics of AV coupling during human atrial fibrillation: role of atrial rate.

The causal relationship between atrial and ventricular activities during human atrial fibrillation (AF) is poorly understood. This study analyzed the effects of an increase in atrial rate on the link between atrial and ventricular activities during AF. Atrial and ventricular time series were determined in 14 patients during the spontaneous acceleration of the atrial rhythm at AF onset. The dynamic relationship between atrial and ventricular activities was quantified in terms of atrioventricular (AV) coupling by AV synchrogram analysis. The technique identified n:m coupling patterns (n atrial beats in m ventricular cycles), quantifying their percentage, maximal length, and conduction ratio (= m/n). Simulations with a difference-equation AV model were performed to correlate the observed dynamics to specific atrial/nodal properties. The atrial rate increase significantly affected AV coupling and ventricular response during AF. The shortening of atrial intervals from 185 ± 32 to 165 ± 24 ms (P < 0.001) determined transitions toward AV patterns with progressively decreasing m/n ratios (from conduction ratio = 0.34 ± 0.09 to 0.29 ± 0.08, P < 0.01), lower occurrence (from percentage of coupled beats = 27.1 ± 8.0 to 21.8 ± 6.9%, P < 0.05), and higher instability (from maximal length = 3.9 ± 1.5 to 2.8 ± 0.7 s, P < 0.01). Advanced levels of AV block and coupling instability at higher atrial rates were associated with increased ventricular interval variability (from 123 ± 52 to 133 ± 55 ms, P < 0.05). AV pattern transitions and coupling instability in patients were predicted, assuming the filtering of high-rate irregular atrial beats by the slow recovery of nodal excitability. These results support the role of atrial rate in determining AV coupling and ventricular response and may have implications for rate control in AF.

Circulating cardiovascular biomarkers in recurrent atrial fibrillation: data from the GISSI-atrial fibrillation trial.

OBJECTIVE: we evaluated the prognostic role of circulating cardiovascular biomarkers in patients with a history of recent atrial fibrillation (AF). BACKGROUND: predicting long-term maintenance of sinus rhythm in patients with AF is difficult. METHODS: plasma concentrations of three specific cardiac markers [high-sensitivity troponin T (hsTnT), N-terminal probrain natriuretic peptide (NT-proBNP) and mid-regional proatrial natriuretic peptide (MR-proANP)] and three stable fragments of vasoactive peptides [mid-regional proadrenomedullin (MR-proADM), copeptin (CT-proAVP) and CT-proendothelin-1 (CT-proET-1)] were measured at baseline and after 6 and 12 months in 382 patients enrolled in the GISSI-AF study, a prospective randomized trial to determine the effect of valsartan to reduce the recurrence of AF. The association between these markers, clinical characteristics and recurrence of AF was tested by univariate and multivariate Cox models. RESULTS: mean patient age was 68 ± 9 years (37.2% females). A total of 84.8% of patients had a history of hypertension. In total, 59.7% qualified for history of AF because of successful cardioversion, 11.8% because of two or more episodes of AF in the 6 months preceding randomization and 28.5% because of both. Patients in AF at 6 or 12 months (203 (53.1%) with first recurrence) had significantly higher concentrations of most biomarkers. Despite low baseline levels, higher concentrations of hsTnT {adjusted hazard ratio (HR) [95% confidence intervals (CIs) for 1 SD increment] (1.15 [1.04-1.28], P = 0.007), MR-proANP (1.15 [1.01-1.30], P = 0.04), NT-proBNP (1.24 [1.11-1.39], P = 0.0001) and CT-proET-1 (1.16 [1.01-1.33], P = 0.03) independently predicted higher risk of a first recurrence of AF. Changes over time of MR-proANP tended to predict subsequent recurrence (adjusted HR [95%CI]) (1.53 [0.98-2.37], P = 0.06). CONCLUSION: circulating markers of cardiomyocyte injury/strain and endothelin are related to recurrence of AF in patients in sinus rhythm with a history of recent AF.

Health technology assessment on reprocessing single-use catheters for cardiac electrophysiology: results of a three-years study.

The study aims to define the technical, ethical, juridical and economic issues involved in the assessment of a reprocessing policy for single-use interventional cardiac devices (SUDs). The feasibility of reprocessing was evaluated for cardiac electrophysiology catheters by comparing the chemical, physical and functional properties of new and reprocessed devices. The issue of hygiene was addressed by developing microbiological tests for the quantification of bioburden, sterility and pyrogenic load. The results of more than 1500 tests, conducted on 531 catheters, suggested a precautionary number of regenerations of five cycles. The ethical aspects were reviewed and the European juridical framework was assessed, revealing a need for harmonization. Applying a specific economic model, potential savings were calculated for a representative cardiology department and estimated at national and European level. Potential savings of 41.2% and 32.9% were calculated for diagnostic and ablation catheters, respectively. Safe and effective reprocessing of SUDs could be pursued if quality control processes and certified procedures are met. A reprocessing policy in EP laboratory could lead to savings of about 27,250 euros per 100,000 population, but the economic benefits are strongly dependent on the maximum number of regenerations and the regeneration rate.

Management of patients with syncope referred urgently to general hospitals.

OBJECTIVE: To evaluate the incidence and the strategy of management of syncope admitted urgently to a general hospital. BACKGROUND: The management of patients with syncope is not standardized. METHODS: The study was a prospective observational registry from a sample of 28 general hospitals in Italy and enroled all consecutive patients referred to their emergency rooms from November 5th 2001 to December 7th 2001 who were affected by transient loss of consciousness as the principal symptom. RESULTS: The incidence of syncope was 0.95% (996 of 105,173 patients attending). Forty-six percent were hospitalized, mostly in the Department of Internal Medicine. The mean in-hospital stay was 8.1+/-5.9 days. A mean of 3.48 tests was performed per patient. A definite diagnosis was made in 80% of cases, neurally-mediated syncope being the most frequent. The findings of each of the 28 hospitals participating in the survey were separately evaluated. We observed great inter-hospital and inter-department heterogeneity regarding the incidence of emergency admission, in-hospital pathways, most of the examinations performed and the final assigned diagnosis. For example, the execution of carotid sinus massage ranged from 0% in one hospital to 58% in another (median 12.5%); tilt testing ranged from 0 to 50% (median 5.8%); the final diagnosis of neurally-mediated syncope ranged from 10 to 78.6% (median 43.3%). CONCLUSION: Great inter-hospital and inter-department heterogeneity in the incidence and management of syncope was observed in general hospitals. As a consequence, we were unable to describe a uniform strategy for the management of syncope in everyday practice.

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.

Efficacy of a dual chamber defibrillator with atrial antitachycardia functions in treating spontaneous atrial tachyarrhythmias in patients with life-threatening ventricular tachyarrhythmias.

BACKGROUND: Atrial fibrillation has a high incidence in patients wearing an implantable cardioverter defibrillator for ventricular tachyarrhythmias and may lead to palpitations, heart failure, angina, stroke and inappropriate defibrillator discharge. The aim of the study was to evaluate the efficacy of a dual chamber defibrillator with atrial antitachycardia functions in treating spontaneous atrial tachyarrhythmias. METHODS: One hundred and twelve patients, 88 male, mean age 64+/-11 years, were enrolled. Seventy-six had ischaemic heart disease, 21 idiopathic dilated cardiomyopathy, nine other heart diseases, six no structural heart disease. The mean left ventricular ejection fraction was 40+/-11%. Sixty-two had prior atrial tachyarrhythmias. RESULTS: Follow-up lasted 11+/-9 months (range 1-42). Among 933 ventricular tachyarrhythmia episodes, 100% of ventricular fibrillation and 92% of ventricular tachycardia were successfully cardioverted. Among 414 detected sustained atrial tachyarrhythmias, 195 were classified as atrial tachycardia (47.1%), 192 as atrial fibrillation (46.4%) and 27 (6.5%) as sinus rhythm. The detection-positive predictive value was 93.5%. Therapy success rates: antitachy pacing on atrial tachycardia = 71.3% (crude estimate); 66.1% (adjusted estimate); 50 Hertz on atrial fibrillation=36.2% (crude estimate); 13.5% (adjusted estimate); atrial shock on atrial fibrillation = 62.5% (mean energy 7.8+/-14.1J). Shock efficacy was 32% when delivered energy was < or = 2 atrial defibrillation threshold at implant and 92% when >2. Duration of successfully treated atrial episodes was significantly lower than that of unsuccessfully treated (6+/-26 min vs 42+/-60). CONCLUSIONS: Atrial antitachy pacing and shock therapies demonstrated very high efficacy in treating atrial tachyarrhythmias in defibrillator patients.

Absence of slowest oscillations in short term heart rate variability of post-myocardial infarction patients. GISSI-3 arrhythmias substudy. GISSI-3 Arrhythmias Substudy Investigators.

Despite the widely demonstrated association of reduced heart rate variability (HRV) to bad prognosis after myocardial infarction (MI), reference values for HRV parameters are still not available. The GISSI-3 Arrhythmias Substudy studied short-term HRV in a relatively unselected population of patients (324) with recent MI (13 +/- 7 days) providing the statistical description of the main time and frequency domain parameters. All HRV indices, except for the RR interval, showed a non-normal distribution generally skewed around the lowest values. Particularly, no LF power was detected in 75 patients (23%) by power spectral analysis. The absence of LF oscillation in RR spectra was associated to the lower standard deviation of normal RR intervals (SD), aging (> 65 years) and blood pressure hypertension. This result seems to indicate a paradoxical effect of sympathetic overactivity in post-MI patients.

Causal linear parametric model for baroreflex gain assessment in patients with recent myocardial infarction.

Spectral and cross-spectral analysis of R-R interval and systolic arterial pressure (SAP) spontaneous fluctuations have been proposed for noninvasive evaluation of baroreflex sensitivity (BRS). However, results are not in good agreement with clinical measurements. In this study, a bivariate parametric autoregressive model with exogenous input (ARXAR model), able to divide the R-R variability into SAP-related and -unrelated parts, was used to quantify the gain (alpha(ARXAR)) of the baroreflex regulatory mechanism. For performance assessing, two traditional noninvasive methods based on frequency domain analysis [spectral, baroreflex gain by autogressive model (alpha(AR)); cross-spectral, baroreflex gain by bivariate autoregressive model (alpha(2AR))] and one based on the time domain [baroreflex gain by sequence analysis (alpha(SEQ))] were considered and compared with the baroreflex gain by phenylephrine test (alpha(PHE)). The BRS evaluation was performed on 30 patients (61 +/- 10 yr) with recent (10 +/- 3 days) myocardial infarction. The ARXAR model allowed dividing the R-R variability (950 +/- 1,099 ms(2)) into SAP-related (256 +/- 418 ms(2)) and SAP-unrelated (694 +/- 728 ms(2)) parts. alpha(AR) (12.2 +/- 6.1 ms/mmHg) and alpha(2AR) (8.9 +/- 5.6 ms/mmHg) as well as alpha(SEQ) (12.6 +/- 7.1 ms/mmHg) overestimated BRS assessed by alpha(PHE) (6.4 +/- 4.7 ms/mmHg), whereas the ARXAR index gave a comparable value (alpha(ARXAR) = 5.4 +/- 3.3 ms/mmHg). All noninvasive methods were significantly correlated to alpha(PHE) (alpha(ARXAR) and alpha(SEQ) were more correlated than the other indexes). Thus the baroreflex gain obtained describing the causal dependence of R-R interval on SAP showed a good agreement with alpha(PHE) and may provide additional information regarding the gain estimation in the frequency domain.

[Arrhythmia risk stratification based on etiological and anatomo-structural factors]. / Stratificazione del rischio aritmico alla luce dei fattori eziologici ed anatomo-strutturali.

In patients with heart failure, sudden death is very common, particularly in subjects in NYHA functional class II and III (respectively 50-80% and 30-50% of all deaths). The mechanisms at the root of sudden death depend on whether heart failure is secondary to an ischemic or non-ischemic heart disease. In ischemic heart disease, sudden death is mainly arrhythmic (ventricular tachycardia/ventricular fibrillation caused by the reentry circuits in the infarct area or by acute ischemic episodes or bradyarrhythmia). In non-ischemic heart disease, the percentage of arrhythmic sudden deaths seems to be lower. Furthermore, a percentage of sudden death cases with heart failure can be linked to electromechanical dissociation and to pulmonary or systemic embolism. Moreover the risk stratification level differs depending on whether heart failure is caused by an ischemic or a non-ischemic heart disease. The various non-invasive studies mainly employed in patients with ischemic heart disease cannot be reliably used to study patients with non-ischemic heart disease. Even the programmed ventricular stimulation demonstrated prognostic reliability only in cases involving ischemic heart disease. The therapeutic approach may also be conditioned by the heart disease responsible for heart failure. To date, for example, all the studies published on primary prevention of sudden death with an implantable defibrillator have been carried out in patients with ischemic heart disease.

Coronary artery narrowing after aortic root reconstruction with resorcin-formalin glue.

Severe stenosis of right and left main coronary artery ostia developed after aortic root reconstruction with gelatin-resorcin-formol glue for correction of acute type A aortic dissection. Surgical treatment of this condition required grafting of the right and left anterior descending arteries with bilateral mammary arteries on the beating heart.

Rigorous proof of fermi liquid behavior for jellium two-dimensional interacting fermions

Using the method of continuous constructive renormalization group around the Fermi surface, we prove that a jellium two-dimensional interacting system of fermions at low temperature T is analytic in the coupling constant lambda for |lambda| |logT|

Spectral and bidirectional filters give different results for signal-averaged ECG analysis in patients with postmyocardial infarction. GISSI-3 Arrhythmias Substudy Investigators.

This study aims at assessing the specific effects of bidirectional filters (BF) and spectral filters (SF) on signal-averaged ECG (SAECG) analysis. The GISSI-3 Arrhythmias Substudy collected SAECGs of 598 patients 10 +/- 4 days after myocardial infarction (MI) from 20 Italian coronary care units. BF and SF were applied on 340 and 258 patients, respectively. QRS duration (QRSD), low amplitude signal duration (LAS40), and root mean-square-voltage (RMS40) were measured with filters set at 40 to 250 Hz. For ventricular late potentials (VLP) detection filter-specific criteria were adopted: QRSD > 114 ms, LAS40 > 38 ms, RMS40 < 20 microV for BF and QRSD > 120 ms, LAS40 > 38 ms, RMS40 < 20 microV for SF. VLP were considered present if any 2 of the criteria were met. The QRSD obtained by BF (100.6 +/- 13 ms) was shorter (P < .0001) than that obtained by SF (109.1 +/- 12 ms). Nevertheless, a higher prevalence of VLP for patients with BF than for patients with SF was found (23.8% vs 16.7%; P < .04). Indeed, filter-specific criteria were able to avoid any differences in the prevalence of abnormal QRSD and LAS40, but not of RMS40 (25.6% vs 17.1%, P < .02). Finally, the difference of VLP prevalence was mainly owing to the higher number of abnormal pairs of RMS40 + LAS40 (58% vs 44%) for BF than for SF. This multicentric study suggests that after MI, BF and SF produce discordant results on low-amplitude signals of filtered QRS that are not avoided by adopting filter-specific criteria. On the contrary, specific criteria seem to be suitable for comparison of QRSD between different SAECG devices in post-MI patients.

Autonomic neural control during acute myocardial ischemia after phenylephrine infusion and subsequent nitroglycerin-induced hypotension and bradycardia.

ST-elevation acute myocardial ischemia occurred after phenylephrine infusion in a patient with severe coronary artery disease and recent myocardial infarction. The subsequent administration of nitroglycerin led to a vasovagal response with symptomatic hypotension and bradycardia. During myocardial ischemia, heart-rate variability and baroreflex sensitivity analysis described a marked activation of sympathetic drive and severe impairment of baroreflex control. The nitroglycerin-induced hypotension-bradycardia was associated with complex changes in the autonomic pattern characterized by subsequent phases of abrupt activation/deactivation of the two limbs of autonomic nervous system developing into a loss of neural control mechanisms.

[An Italian experience of radiofrequency transcatheter ablation in type-I atrial flutter: the results and follow-up]. / Un'esperienza italiana sull'ablazione transcatetere con radiofrequenza nel flutter atriale tipo I: risultati e follow-up.

BACKGROUND: Type I atrial flutter (AF) is a supraventricular tachycardia that is notoriously disabling and resistant to antiarrhythmic drugs. The introduction of an effective non-pharmacologic technique, such as radiofrequency catheter ablation (RF), opened new therapeutic prospects for the management of this arrhythmia. The aim of our study was to evaluate the long-term efficacy of atrial flutter RF using a successful procedure marker of bi-directional conduction block in the isthmus. METHODS: In the last consecutive 50 patients (pts) who underwent RF procedure for AF at our Center (46 pts during spontaneous or induced AF and 4 in sinus rhythm) after the successful interruption of AF we performed the usual reinduction attempts and well atrial pacing from 2 sites in the right atrium (in 18 pts before and after RF and in 32 only after RF). The sites of pacing were site 1: low lateral right atrium (LRA); site 2: proximal coronary sinus (PCS). The 50 pts consisted of 13 females, 37 males with a mean age of 62.5 +/- 9.7 years (35-83). The end-point for the procedure was: 1) abrupt interruption of AF; 2) inability to reinduce AF; 3) recognition of atrial activation sequence during pacing in LRA and in PCS compatible with conduction block in the isthmus. RESULTS: The RF was successful in terminating AF in all pts after 11 +/- 7 applications of energy. After ablation, sustained AF was no longer inducible by atrial pacing. After RF, during pacing in sinus rhythm from LRA, the lower septum and PCS presented a delayed activation after the His region. Similarly, during pacing from PCS after ablation, the atrial activation sequence was modified: the low lateral right atrium was now activated by a single front after the high lateral atrium. No acute complications were noted in any pts during or after procedure. AF recurred in 9 pts. Four pts now present chronic atrial fibrillation. The mean follow-up period is 14.8 +/- 8 months. All the patients were discharged without antiarrhythmic therapy. CONCLUSIONS: The mechanism of successful ablation is the bi-directional conduction block in the isthmus with the evidence of the changes in the right atrial activation sequence during atrial pacing in sinus rhythm in LRA and in PCS before and after RF.

[Congenital arterio-venous coronary fistula associated with patent ductus arteriousus: description of a clinical case and review of the literature]. / Fistola artero-venosa coronarica congenita associata a dotto arterioso pervio: descrizione di un caso clinico e revisione della letteratura.

Congenital coronary artery fistulae are rare anomalies (0.27-0.4% of all congenital heart defects) and consist of a communication between a coronary artery and a cardiac chamber, a great artery or the superior vena cava. The association of these congenital anomalies with other congenital cardiovascular defects is unusual. The purpose of this paper is to report a case of congenital coronary fistula between the anterior descending coronary artery and the pulmonary artery associated with patent ductus arteriosus and to review the literature on the subject.

[Effects of filtering techniques on time-domain analysis of signal-averaged ECG after acute myocardial infarction: a multicenter study, GISS-3 arrhythmia sub-project]. / Effetti delle techniche di filtraggio sull'analisi nel dominio del tempo del signal-averaged ecg dopo infarto miocardico acuto: studio multicentrico, GISSI-3 sottoprogetto aritmie. GISSI-3 Sottoprogetto Aritmie (Elenco dei Centri in ultima pagina).

AIM OF THE STUDY: To evaluate the influence of different filtering techniques on the measurement of ventricular late potentials (VLP) the Sottoprogetto Aritmie of GISSI-3 collected signal-averaged ECG (SAECG) from 647 patients. METHODS: Data were recorded after myocardial infarction (10 +/- 4 days) in 20 Italian Coronary Units. Three main filtering algorithms were used in the different commercial devices: Bidirectional Filter (ART, Aerotel, Fidelity Medical) (BF: 340 Patients), Spectral Filter (Marquette) (SF: 258 Patients) and Del Mar Filter (Del Mar Avionics) (DF: 49 Patients). QRS duration (QRSD), low amplitude signal duration (LAS40) and root mean-square-voltage (RMS40), were measured with various filters set at 40-250 Hz high and low pass frequencies. RESULTS: After correction for clinical variables the measurements of VLP in the three different groups were different. QRSD value obtained by BF (100.6 +/- 13 ms) was shorter than that obtained by SF (109.1 +/- 12 ms). No differences were found in LAS40 and RMS40 values between SF and BF, while DF gave longer LAS40 and lower RMS40 than SF and BF. Residual noise was lower in BF (0.3 +/- 0.1 muV). than in SF and DF (0.5 +/- 0.1 muV). Applying standard criteria DF gave a higher prevalence of VLP (48.9%) than BF (23.8%) and SF (19%) groups. CONCLUSIONS: This study demonstrates that the use of different filters produces discordant result on VLP measurements. For correct application of SAECG analysis in risk stratification after myocardial infarction, normal and abnormal values must be specifically established for the different filter techniques.

[Heart rupture at the right atrial level as the first manifestation of malignant lymphoma]. / Rottura di cuore a livello atriale destro come prima manifestazione clinica di linfoma maligno.

Primary heart lymphoma is an extremely rare condition and metastatic lymphomas constitute 9% of the total heart metastases. In most cases the lymphomatous involvement of the heart and/or pericardium is seen only at autopsy. It is unlikely that cardiac manifestations are the initial presentation of malignant lymphoma. We report a case of malignant lymphoma presenting with cardiac tamponade secondary to right atrial rupture.