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.

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|

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.

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.

Clinical evaluation of new antiarrhythmic agents: experiences with propafenone.

The authors propose a general design for the clinical evaluation of new antiarrhythmic agents with special reference to their experience with propafenone, a new Class 1 agent. The drug was studied in 61 patients affected by PSRT, VEBs or RVT often unresponsive to other drugs. Both acute i.v. sensitivity tests and evaluation of chronic oral treatment were carried out. The results indicate that propafenone is a highly effective drug and that its oral activity may be predicted in individual patients by an acute i.v. administration. The most frequent adverse reaction was a widening of QRS complex. However the drug had to be withdrawn due to impaired intraventricular conduction in one patient only. More frequently (four cases) its withdrawal was due to adverse extracardiac reactions.

[Anti-arrhythmic therapy with verapamil by intravenous infusion]. / Terapia antiaritmica con il verapamil per infusione endovenosa

Rapid and slow venous infusion of various doses of Verapamil in a mixed series of 185 cases of arrhythmia since 1968 is reported. Results and electrophysiological and ECG changes observed for each type of arrhythmia examined are considered separately: atrial fibrillation-flutter, supraventricular paroxystic tachycardia (atrial and/or junctional), and hyperkinetic ventricular arrhythmia. An association of i.v. Verapamil and a quinidine salt per os is suggested as an alternative to cardioversion in cases of recent atrial fibrillation-flutter. Results obtained in the treatment of arrhythmia due to electrical instability following angina and of angina following arrhythmia are also described. A study of His potentials as the premiss for using Verapamil in subjects with stimulus conductivity changes, including W.P.W. syndrome, is also reported. I.v. Verapamil was used in association with atrial and/or ventricular electrostimulation, and/or with electrical counter-shock in cases of arrhythmia (mostly supraventricular) that were especially refractory. Attention is drawn to the use of Verapamil in the control of arrhythmia after electrical cardioversion.

[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.

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.

[The use of pace-makers with programmable frequency in the control of hyperkinetic ventricular "refractory" arrhythmia (author's transl)]. / L'impiego dei pace-makers a frequenza programmabile nel controllo delle aritmie ipercinetiche ventricolari "refrattarie".

The electrophysiological basis of the treatment of hyperkinetic "refractory" arrhythmias with rate - programmable pacemakers, stems from the pacing-inducted electrophysiological modifications with higher and time programmable threshold rates being obtainable to suppress the arrhythmias. Furthermore antiarrhythmic agents, that must be generally associated, are more safely employed. This is a new application in clinical arrhythmology of a particular type of permanent pacemaker whose classic indications are well known. The Authors report their experience relative to 16 selected patients affected by severe cardiopathies. Three types of pacemakers were employed: Omnis Stanicor Cordis; Microlith C.P.I.; and Byrel A-V Sequential, Medtronic. The results, in term of the suppression of the arrhythmias, were encouraging. The most striking problem is to match the "rate threshold" for the suppression of the arrhythmia with the patient's hemodynamic tolerance: not infrequently in fact the programmed rates are poorly tolerated by the patient either because of heart failure or due to coronary insufficiency. These patients need frequent adjustment of the stimulation rate. The availability of rate programmable pacemakers with steps of one beat per minute, of A-V sequential stimulation and, when feasible of atrial stimulation, undoubtedly plays an important role in clinical arrhythmology.

[Natural history of persistent atrial paralysis. Description of a case with familial and evolutionary characteristics]. / Contributo alla conoscenza della storia naturale della paralisi atriale persistente. Descrizione di un caso a carattere familiare ed evolutivo.

We report a case of partial persistent atrial standstill from a group of patients with familial endemic complete or partial persistent atrial standstill. In this patient we observed the evolution from sinus rhythm (with episodes of uncommon atrial flutter treated by electrostimulation) to the typical clinical picture of partial persistent atrial standstill, which is described also in its electrophysiological features. Incomplete and complete persistent atrial standstill may represent different stages of the same disease of the atrial wall.

Evidence of low- and high-frequency oscillations in human AV interval variability: evaluation with spectral analysis.

The spontaneous beat-to-beat variation of atrioventricular (AV) interval was analyzed in time and frequency domains and compared with atrial cycle length (A-A) variability. The analysis was applied in humans at rest and tilt position during sinus rhythm and atrial pacing. The AV intervals showed spontaneous oscillations of small amplitude with a relative standard deviation of 1.8%. Spectral analysis of AV interval series showed the existence of two main oscillatory components at low frequency (LF; 0.04-0.13 Hz) and at high frequency (HF; 0.17-0.4 Hz), synchronous with those of A-A interval series. The same LF and HF fluctuations were found in AV interval variability during atrial pacing. Tilt maneuver inducing a sympathetic stimulation and vagal withdrawal increased LF power and decreased HF power of A-A interval spectra (P < 0.05). On the contrary, tilt decreased the LF (46%, P < 0.05) and HF power (29%, P = NS) of AV conduction spectra. In parallel, tilt decreased (P < 0.0001) the mean A-A interval, leaving the mean AV interval unchanged. When heart rate was held constant by atrial pacing, tilt reduced the mean AV interval, the LF power (65%, P < 0.05), and HF power (10%, P = NS). These results indicate a direct influence of the autonomic nervous system on the LF and HF oscillations of AV conduction. The decrease of AV interval oscillations during tilt demonstrates a marked reduction of autonomic modulation of AV conduction mainly attributable to parasympathetic withdrawal.

[Tricuspid insufficiency with rupture of the chordae tendineae caused by closed thoracic trauma: evaluation by transesophageal echocardiography. Description of a case]. / Insufficienza tricuspidale con rottura di corde tendinee secondaria a trauma toracico chiuso valutata con ecocardiografia transesofagea. Descrizione di un caso.

A case of severe tricuspid insufficiency with ruptured chordae tendineae due to nonpenetrating major chest trauma caused by a car accident is described. Electrocardiographic signs of complete right bundle branch block and olosystolic murmur were present and not observed before. Transthoracic echocardiography showed a significant prolapse of the septal tricuspid leaflet with severe tricuspid regurgitation and severe right heart overload, which progressively worsened. Transesophageal echocardiography confirmed the transthoracic echocardiographic findings. It also demonstrated the presence of ruptured chordae tendineae and the coexistence of a severe prolapse of the tricuspid anterior leaflet with flail movement. Although the patient remained asymptomatic, these findings prompted us to refer the case to the surgeon. The patient underwent valvuloplasty with excellent late result. In presence of traumatic tricuspid insufficiency the use of transesophageal echocardiography can be helpful to optimize the anatomic evaluation of the valvular apparatus allowing adequate therapeutic decision.

[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.