Clinical, electrocardiographic and electrophysiological predictors of atrial fibrillation development in different cardiac substrates.

We performed a review of the current literature in order to evaluate clinical, electrocardiographic and electrophysiologic parameters predictive of atrial fibrillation development. Clinical parameters were obtained from two large observational studies (the Framingham heart study and the Cardiovascular health study). Different laboratoristic predictors were also reviewed: ECG-derived predictors, among which we separately evaluated those derived from the 12-lead surface ECG and those derived from the signal averaged P-wave, and other electrophysiologic predictors as atrial monophasic action potential analysis. We also evaluated the clinical value of these different parameters in atrial fibrillation in patients with no overt structural heart disease and in the most common clinical conditions known to be related to atrial fibrillation development such as hypertension, heart failure, cardiovascular surgery.

Vascular and haemostatic gene polymorphisms associated with non-fatal myocardial infarction: a critical review.

The importance of genetics to the pathogenesis of myocardial infarction is suggested by the frequent familial clustering of premature disease. Yet, studies associating myocardial infarction with gene polymorphisms of vascular proteins (angiotensinogen, angiotensin converting enzyme, angiotensin II type 1 receptor, endothelial nitric oxide synthase) and haemostatic factors (fibrinogen, coagulation factors II, V, VII and XIII, plasminogen activator inhibitor-1, tissue-type plasminogen activator, platelet glycoproteins IIb/IIIa, Ia/IIa and Ib-IX-V, or methylenetetrahydrofolate reductase) have revealed conflicting results. This is hardly surprising, given: 1) the multigenic nature of myocardial infarction, whereby single polymorphisms are bound to play at best only a limited role in the global risk of disease; 2) the multiple pathogenetic mechanisms of infarction (e.g., atheromatous obstruction, plaque rupture, thrombosis, vasospasm), each of which is likely influenced by a number of genes and by several environmental factors. The simultaneous investigation of a set of polymorphisms--and of their interactions with environmental factors--in extremely homogeneous sets of patients should offer a better understanding of the contribution of specific genes to the risk of myocardial infarction.

Additional predictive value of heart rate variability in high-risk patients surviving an acute myocardial infarction.

The aim of this study was to investigate the usefulness of heart rate variability (HRV) in predicting cardiac mortality in patients with a recent acute myocardial infarction at high risk of events. Time- and frequency-domain HRV was assessed on 24-hour pre-discharge Holter recording of 81 patients (mean age 65 +/- 10 years, 76.5% males) with 1) a recent acute myocardial infarction, and 2) left ventricular ejection fraction < 40% and/or a number of premature ventricular beats > or = 10/hour. There were 15 total cardiac deaths (18.5%) in a follow-up time of 29 +/- 15 months (range 6 to 48 months), with sudden death occurring in 11 patients (13.6%). Median values of low frequency (LF) were lower in patients with, compared to those without, total (p = 0.04) and sudden (p = 0.02) cardiac death. Similarly the low frequency/high frequency (LF/HF) ratio was lower in patients with fatal events (p = 0.03 and p = 0.02, respectively). Furthermore, mean of the standard deviations of all RR intervals for all 5-min segments < 20 ms, among time-domain variables, and very-low frequency (VLF) < 18 ms, among frequency-domain variables, significantly predicted cardiac death (relative risk-RR 2.94, p = 0.03; and RR 3.85, p < 0.005, respectively). Furthermore, VLF < 18 ms and LF/HF ratio < 1.05 significantly predicted the occurrence of sudden death (RR 3.52, p = 0.04; and RR 3.49, p = 0.04, respectively). Thus, our data show that HRV analysis is a useful tool for identifying patients with an actual increased risk of fatal cardiac events among patients who are basically considered at high risk according to the presence of an impaired left ventricular function and/or frequent ventricular arrhythmias.

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.

Acute coronary syndromes in women: pathophysiology and therapeutic options.

Patients presenting with acute coronary syndromes disclose a number of gender-related differences. Women are more likely than men to have unstable angina and less likely to present with myocardial infarction. Women have a better prognosis than men among patients with unstable angina. Among patients with myocardial infarction without ST-segment elevation, men and women show similar outcomes. In contrast, among patients with myocardial infarction and ST-segment elevation, women consistently show a worse prognosis than men. This difference is not fully explained by age, comorbidities, extent of epicardial artery disease, or baseline left ventricular function, and may reflect gender differences in pathophysiological, functional and anatomical variables. Moreover, revascularization procedures and several anti-ischemic drugs appear underutilized in women.

Circadianicity of hemostatic function and coronary vasomotion.

Acute myocardial infarction, sudden cardiac death and ischemic stroke show a circadian periodicity, occurring more frequently in the morning. Because arterial thrombosis is common to these disorders, a circadianicity of prothrombotic and antithrombotic processes may contribute to explain the 24 h rhythms of these acute events. Available data indeed indicate that coronary vasomotor tone, platelet aggregability, plasma inhibition of fibrinolysis, coagulant activity and blood viscosity are all greater in the morning than at other times of day, producting a relative prothrombotic state in the early morning.

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.

[Mitral valve prolapse and pregnancy]. / Il prolasso della mitrale e la gravidanza.

13 cases of MVP in pregnancy were examined and compared with a control group. No significant differences were found in the various parameters assessed in the two groups nor did there appear to be any significant increase in obstetric or neonatal risk.

Oral nifedipine in the long-term management of severe chronic heart failure.

We evaluated the hemodynamic effects of nifedipine in 10 symptomatic patients with chronic refractory heart failure due to idiopathic cardiomyopathy. Nifedipine significantly increased cardiac index (from 1.80 +/- 0.4 to 3 +/- 0.6 L/min/m2), stroke volume index (from 21 +/- 6 to 33 +/- 8 ml/beat/m2), and stroke work index (from 17.9 +/- 7 to 25.5 +/- 7 g-m/m2). The drugs also produced a significant decrease in left ventricular filling pressure (from 24.6 +/- 3 to 19 +/- 2 mm Hg), mean blood pressure (from 86 +/- 9 to 74 +/- 5 mm Hg), mean pulmonary arterial pressure (from 31.9 +/- 5 to 25.6 +/- 3 mm Hg), total systemic vascular resistance (from 2,104 +/- 329 to 1,088 +/- 249 dyn/s/cm-5), and pulmonary vascular resistance (from 200 +/- 71 to 107 +/- 50 dyn/s/cm-5). Heart rate remained unchanged. In all patients maintained on nifedipine therapy, repeat hemodynamic studies at 2 months revealed sustained effects, and all patients had symptomatic improvement of at least one New York Heart Association (NYHA) functional class. Long-term treatment was well tolerated. Forty-eight hours after discontinuation of nifedipine administration the hemodynamic benefits were lost. We conclude that nifedipine may be of value for long-term ambulatory therapy of severe chronic heart failure.

Familial hypertrophic cardiomyopathy: vectorcardiographic findings in echocardiographically unaffected relative.

The electrocardiographic and vectorcardiographic (Frank system) features of the first degree relatives of subjects with documented familial hypertrophic cardiomyopathy were analysed. A total of nine affected members and 29 relatives were examined in four families. THe subjects were considered to be affected when the septal to free posterior wall thickness ratio exceeded 1.3 at M-mode echocardiography. Four relatives had asymmetric septal hypertrophy. Among 25 relatives without evidence of asymmetric septal hypertrophy, two over 20 years and 10 under 20 years of age showed increased voltage of QRS anterior forces (Qz amplitude greater than 0.80 mV) on the orthogonal electrocardiogram. The vectorcardiographic data of the relatives under 20 years of age without evidence of asymmetric septal hypertrophy (18 subjects) were compared with those of 38 normal control subjects of comparable age range. The young relatives without disproportionate septal hypertrophy had significantly greater Qz amplitude and Q/Rz ratio than the normal control subjects. In contrast, the echocardiographic data were not significantly different. We suggest that the electrocardiographic finding of abnormal anterior forces in one or more first degree relatives of subjects with documented hypertrophic cardiomyopathy may constitute a valuable aid in ascertaining the genetic transmission of the disease and in recognising affected members without echocardiographic evidence of hypertrophic cardiomyopathy.

Inotropic and electrophysiological effects of tolbutamide in normal subjects.

The acute cardiac effects of tolbutamide on myocardial contractility, evaluated with systolic time intervals (ST), and on the atrio-ventricular conduction system have been studied in a group of five volunteer normal subjects. The intravenous administration of 1 g of tolbutamide showed no considerable changes of STI and of electrophysiologic parameters. Glycemia decreased whereas there was a statistically significant increase in plasmatic levels of catecholamines at the 10th and 20th min. Our findings suggest that the intravenous administration of tolbutamide has no effect either on the atrio-ventricular conduction system or on myocardial contractility in normal men.

Severe involvement of the conduction system in a patient with sclerodermal heart disease. An electrophysiological study.

A case of progressive systemic sclerosis with syncopal symptoms is reported. The presenting ECG pattern was that of an anterior myocardial infarction. The clinical history and the coronary angiography excluded significant coronary atherosclerotic heart disease. The ECG pattern evolved from the infarctual pattern associated with right bundle branch block to probably major degree of right bundle branch block associated with left posterior fascicular block. M-mode echocardiography, heart catheterization and angiographic studies did not reveal significant mechanical impairment of the left or right ventricle function. His bundle electrogram documented a markedly prolonged H-V interval, confirming an advanced impairment of distal conducting system. This case supports the suggestion that intraventricular conduction disorders in sclerodermal heart disease are not always related to diffuse myocardial involvement. The risk of sudden death justifies accurate electrophysiological evaluation in selected patients with sclerodermal cardiopathy.