Maria Cristina Porciani

Interatrial septum pacing: A new approach to prevent recurrent atrial fibrillation.

Background. There are a variety of approaches to the prevention of atrial fibrillation (AF) with pacing. Aim of this study was to test the safety and feasibility of interatrial septum pacing at the posterior triangle of Koch for AF prevention and to exclude potential arrhythmic effects.Matherial and Methods.Interatrial septum pacing was performed in 34 patients (21 males, 13 females, mean age 69±12 years): 9 without a history and clinical evidence of atrial fibrillation (AF) (6 with sinus bradycardia, 2 with second-degree AV block, and 1 with carotid sinus hypersensitivity) and 25 with sinus bradycardia and paroxysmal atrial fibrillation (PAF) (mean symptomatic episodes/month 6.2±10). In all patients a screw-in bipolar lead was positioned in the interatrial septum superiorly to the coronary sinus.Results.At implant the mean P wave amplitude was 2.5±1.5 mV, the pacing threshold was 1±0.6 V and the impedance was 907±477 Ohm. Mean P wave duration was 118±17 ms in sinus rhythm and 82±15 during interatrial septum pacing (p < 0.001). During a mean follow-up period of 10±7 months, no patients without atrial tachyarrhythmias before implantation experienced AF. During a 9±6 months follow-up we observed only 2 symptomatic arrhythmia recurrences between AF patients (mean symptomatic episodes/month 0.006±0.0022) (p < 0.01 vs before implant period).Conclusions. Our data indicate that interatrial septal pacing is safe and feasible. A significant less incidence of arrhythmic episodes has been observed during follow-up. Further controlled randomized prospective studies are necessary to establish the exact role of this technique respect to conventional or multisite stimulation when patients with paroxysmal AF need to be permanently paced.

P Wave Assessment: State of the Art Update

Diagnostic (mapping) and therapeutic (ablation, pacing) advances have provided insight into atrial depolarization processes and new developments in P wave analysis. Information about interatrial pathways is important to the understanding of interatrial conduction delay. A standardized method for P wave analysis is necessary for the development of a clinical role for management of patients with paroxysmal atrial fibrillation using signal-averaged P wave analysis and P wave dispersion. Algorithms for predicting localization of ectopic P waves may facilitate catheter ablation. P wave changes due to pacing at different atrial sites may be useful for permanent pacing for prevention of atrial fibrillation. Introduction of these developments into clinical practice should allow better prevention and treatment of atrial arrhythmias and could have considerable impact in view of their high frequency especially in the older population.

Cardiac resynchronization therapy : Gender related differences in left ventricular reverse remodeling

Cardiac resynchronization refers to pacing techniques that change the degree of atrial and ventricular electromechanical asynchrony in patients with major atrial and ventricular conduction disorders. Atrial and ventricular resynchronization is usually accomplished by pacing from more than one site in an electrical chamber--atrium or ventricle--and occasionally by stimulation at a single unconventional site. Resynchronization produces beneficial hemodynamic and antiarrhythmic effects by providing a more physiologic pattern of depolarization. Atrial resynchronization may prevent atrial fibrillation in selected patients with underlying bradycardia or interatrial block. Its antiarrhythmic effect in the absence of bradycardia is unclear. Ventricular resynchronization is of far greater clinical value than atrial resynchronization. Biventricular (or single-chamber left ventricular) pacing is beneficial for patients with congestive heart failure, severe left ventricular systolic dysfunction, dilated cardiomyopathy (either ischemic or idiopathic), and a major left-sided intraventricular conduction disorder, such as left bundle branch block. The change in electrical activation from resynchronization, which has no positive inotropic effect as such, is translated into mechanical improvement with a more coordinated left ventricular contraction. Several recent randomized trials and a number of observational studies have demonstrated the long-term effectiveness of ventricular resynchronization in the above group of patients. The high incidence of sudden death among these patients has encouraged ongoing clinical trials to evaluate the benefit of a system that combines biventricular pacing and cardioversion-defibrillation into a single implantable device.Aim: Gender related differences in epidemiology, treatment, and prognosis of heart failure (HF) have been reported. We examined the sex influence in patients treated with cardiac resynchronization therapy (CRT).

Effect of isoproterenol on the “early repolarization” syndrome

A study has been carried out on a group of subjects with RS-T segment elevation, a normal variant of early repolarization. Following isoproterenol administration, the RS-T segment became isoelectric. In most cases this was accompanied by shorter QT and longer QTc intervals. The same effects were observed after physical exertion but not after atropine or amyl-nitrite. Propranolol administration exaggerated RS-T elevation. Considering the mechanism with which isoproterenol acts and some analogies with the electrocardiographic picture experimentally obtained by means of the unilateral stimulation of the stellate ganglions, the hypothesis is advanced that the normal variant of early repolarization is related to an enhanced activity of the right sympathetic nerves.

Cardiac Resynchronization Therapy

Cardiac resynchronization refers to pacing techniques that change the degree of atrial and ventricular electromechanical asynchrony in patients with major atrial and ventricular conduction disorders. Atrial and ventricular resynchronization is usually accomplished by pacing from more than one site in an electrical chamber--atrium or ventricle--and occasionally by stimulation at a single unconventional site. Resynchronization produces beneficial hemodynamic and antiarrhythmic effects by providing a more physiologic pattern of depolarization. Atrial resynchronization may prevent atrial fibrillation in selected patients with underlying bradycardia or interatrial block. Its antiarrhythmic effect in the absence of bradycardia is unclear. Ventricular resynchronization is of far greater clinical value than atrial resynchronization. Biventricular (or single-chamber left ventricular) pacing is beneficial for patients with congestive heart failure, severe left ventricular systolic dysfunction, dilated cardiomyopathy (either ischemic or idiopathic), and a major left-sided intraventricular conduction disorder, such as left bundle branch block. The change in electrical activation from resynchronization, which has no positive inotropic effect as such, is translated into mechanical improvement with a more coordinated left ventricular contraction. Several recent randomized trials and a number of observational studies have demonstrated the long-term effectiveness of ventricular resynchronization in the above group of patients. The high incidence of sudden death among these patients has encouraged ongoing clinical trials to evaluate the benefit of a system that combines biventricular pacing and cardioversion-defibrillation into a single implantable device.Aim: Gender related differences in epidemiology, treatment, and prognosis of heart failure (HF) have been reported. We examined the sex influence in patients treated with cardiac resynchronization therapy (CRT).

Tissue Doppler and strain imaging: a new tool for early detection of cardiac amyloidosis.

Using traditional echocardiography, the diagnosis of cardiac amyloidosis (CA) is often only possible in advanced stage when recommended therapies may have adverse effects. The aim of our study was to evaluate whether additional information can be derived from Tissue and strain Doppler imaging (TDI and SDI). Forty patients with systemic amyloidosis and 24 healthy subjects underwent traditional, tissue and strain Doppler echocardiography. Patients were classified having CA if mean wall thickness (mT), was half of the sum septum and posterior wall thickness, was ≥12 mm. The following parameters were evaluated: peak early diastolic velocity (Em) as index of ventricular relaxation, mitral E-wave to Em ratio (E/Em) as index of left ventricular (LV) filling pressure and mean LV strain peak curves (mSt) as global long-axis contraction index. In non cardiac amyloidosis (NCA), both Em and mSt were lower than in age matched controls (p < 0.01, p < 0.05, respectively) and higher than in CA (p < 0.01 and p < 0.01, respectively). Both Em and mSt were related to mT (p < 0.001). A significant (p < 0.01) nonlinear relation was observed between plasma terminal of pro B-natriuretic peptide and mT, Em, E/Em and mSt. TDI and SDI are able to detect amyloid myocardial involvement in such an early stage that cannot be evidenced by using traditional echocardiography.

Dual-site left ventricular cardiac resynchronization therapy.

Simultaneous stimulation of 2 left ventricular (LV) sites could enhance the effectiveness of cardiac resynchronization therapy (CRT). The aim of this study was to evaluate the acute hemodynamic response to dual-site LV CRT. Two LV pacing leads were successfully implanted in 12 CRT candidates (New York Heart Association classes III to IV, QRS >or=120 ms). Target positions were the lateral or posterolateral vein (site A) and anterior or anterolateral vein (site B). A conductance catheter was placed in the left ventricle for pressure-volume measurements. Tested CRT configurations were alternated by atrial overdrive pacing at a fixed rate and included site A and B single-site CRT and dual-site LV CRT (2 LV sites plus right ventricular apex) at 4 atrioventricular intervals. Overall, single-site LV CRT significantly enhanced stroke volume, stroke work, maximum pressure derivative, and conductance-derived indexes of LV synchrony when delivered in site A, whereas no significant changes were noticed with pacing in site B. Specifically, site-A pacing resulted in a higher stroke volume increase (LV pacing site associated with the best hemodynamic response [best-LV]) in 8 patients, and site-B pacing, in 4 patients. At intermediate atrioventricular intervals, dual-site LV CRT resulted in improved stroke volume, stroke work, maximum pressure derivative, and LV synchrony with respect to single-site CRT when delivered at the best-LV (all p <0.05). However, single-site CRT at best-LV produced results similar to dual-site LV CRT when the atrioventricular interval was optimized in each patient. In conclusion, adding a second LV lead does not result in further improvement in acute hemodynamic response with respect to standard CRT when the single LV pacing site and atrioventricular interval are optimal.

Atrioventricular interval optimization in the right atrial appendage and interatrial septum pacing: a comparison between echo and peak endocardial acceleration measurements.

PADELETTI, et al.: Atrioventricular Interval Optimization in the Right Atrial Appendage and Interatrial Septum Pacing: A Comparison Between ECHC and Peak Endocardial Acceleration. Interatrial septum pacing (IASP) reduces interatrial conduction time and consequently may interfere with atrioventricular delay (AVD) optimization. We studied 14 patients with an implanted BEST Living system device able to measure peak endocardial acceleration (PEA) signal. The aims of our study were to compare the (1) optimal AVD (OAVD) in right atrial appendage pacing (RAAP) and IASP, and (2) OAVD derived by the PEA signal versus OAVD derived by Echo/Doppler evaluation of the left ventricular filling time (LVFT) and cardiac output (CO). Measurements were performed in DDD VDD modes Eight patients (group A) had RAAP and six patients (group B) had IASP. In group A, OAVD measured by LVFT, CO, and PEA was 185 ± 23 ms, 177 ± 19 ms, and 192 ± 23 ms in DDD and 147 ± 19 ms, 135 ± 27 ms, and 146 ± 20 ms in VDD, respectively. OAVD measured by LVFT, CO, and PEA was significantly longer in DDD mode than in VDD (P < 0.01, P < 0.01, P < 0.001). In group B, OAVD measured by LVFT, CO, and PEA was 116 ± 19 ms, 113 ± 10 ms, and 130 ± 30ms in DDD and 106 ± 16 ms, 96 ± 15 ms, and 108 ± 26 ms in VDD, respectively. No statistical differences were observed between DDD and VDD. Significant correlations between OAVDs PEA derived and OAVDs LVFT and CO derived were observed (r = 0.71, r = 0.69, respectively). When new techniques of atrial stimulation, as IASP, are used an OAVD shorter and similar in VDD and DDD has to be considered. The BEST Living system could provide a valid method to ensure, in every moment, the exact required OAVD to maximize atrial contribution to CO.

Rotational mechanics of the left ventricle in AL amyloidosis.

Aims: The aim of this study was to investigate whether alterations in left ventricular (LV) twisting and untwisting motion could be induced by cardiac involvement in patients with immunoglobulin light‐chain (AL) systemic amyloidosis. Methods and Results: Forty‐five patients with AL amyloidosis and 26 control subjects were evaluated. After standard echocardiographic measurement and two‐dimensional (2D) speckle tracking echocardiography, LV rotation at both basal and apical planes, twisting, twisting rate, and longitudinal strain were measured. Tissue Doppler imaging (TDI) derived early diastolic peak velocity at septal mitral annulus (E′) was also evaluated. Twenty‐six of 45 patients with systemic amyloidosis were classified as having cardiac amyloidosis (CA) if the mean value of the LV wall thickness was ≥ 12 mm or not (NCA) if this value was not reached. In NCA patients, both LV twist and untwisting rate were increased while they were decreased in CA patients making them similar to the control group. Longitudinal strain was reduced only in CA patients. Impaired relaxation as indicated by E′ values was progressively reduced in the course of the disease. Conclusions: Both twisting and untwisting motions are increased in patients with AL systemic amyloidosis with no evidence of cardiac involvement while they are reduced in patients with evident amyloidosis cardiac involvement. This finding suggests that impaired LV relaxation induces a compensatory mechanism in the early phase of the disease, which fails in more advanced stage when both twisting and untwisting rates are reduced. The increase in LV rotational mechanics could be a marker of subclinical cardiac involvement. (Echocardiography 2010;27:1061‐1068)

Influence of Age, Lead Axis, Frequency of Arrhythmic Episodes, and Atrial Dimensions on P Wave Triggered SAECG in Patients with Lone Paroxysmal Atrial Fibrillation

Signal‐averaged P wave of 42 patients with lone paroxysmal atrial fibrillation (PAF) and 29 normal subjects (N) were recorded, using three orthogonal leads and analyzed in the time and frequency (entire P wave or a 100‐ms segment ranging from 75 ms before to 25 ms after the end of P wave) domains. PAFs were divided into a group of 12 having ≥ 2 attacks a month (HF) and a group of 30 having ≤ 2 attacks a year (LF). Statistically significant differences were absent with regard to ages of PAF and N; ages of HF, LF, and N at the time of signal‐averaged ECG; ages of HF and LF at the time of the first arrhythmic episode; and elapsed times from the first episode. Length of P wave and some frequency‐domain parameters were found to be significantly correlated with age. PAF showed a significantly longer duration of P wave in the frontal plane using the time‐domain analysis. Frequency analysis was found to be useful in evaluating the influence of attack frequency. HF showed significantly higher values of some frequency‐domain parameters than LF and N, while the three groups did not differ for time‐domain analysis. P wave duration and frequency content of the three orthogonal leads proved to be significantly different in PAF and N. Right and left atrial echocardiographic dimensions proved to be higher (even if within normal limits) in HF than in LF and N. Results suggest that frequency analysis should be performed on the entire P wave.