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Biomedical subjects

Massimo Santini

Publications and source records attributed to Massimo Santini.

At least 37 records · Page 2Linked to original sources
PubMed2005

Long-term reduction of atrial tachyarrhythmia recurrences in patients paced for bradycardia-tachycardia syndrome.

BACKGROUND: Atrial tachyarrhythmias (AT) are considered progressive diseases. Several rhythm control therapies for treatment of AT have been proposed. OBJECTIVES: The Italian AT500 Registry was designed to prospectively study long-term AT evolution in patients paced for the brady-tachy form of sinus node disease (BT-SND). METHODS: Three hundred forty-six BT-SND patients received an antitachycardia dual-chamber pacemaker and were followed-up for a minimum of 12 months (median 19 months). Prevention and antitachycardia pacing (ATP) features were enabled in all patients. RESULTS: During the observation period, 224 (65%) patients were treated by antiarrhythmic drugs and 45 (13%) patients were cardioverted. Five patients suffered a stroke, 4 transient ischemic attack, 22 permanent AT, and 98 AT recurrences longer than 7 days. AT mean cycle length changed from 246 to 270 ms, and the percentage of patients with AT-related hospitalizations significantly decreased with an annual 28% relative reduction. AT burden and the percentage of patients with AT recurrences longer than 2 days remained constant with time in the overall population but decreased significantly in the subgroup of patients who did not develop permanent AT. High ATP efficacy was associated with an increasingly higher prevention of AT recurrences longer than 2 days. CONCLUSION: In a long-term observation of BT-SND patients, AT-related hospitalizations decreased significantly and mean AT cycle length increased significantly. The data suggest that rhythm control therapies induce inversion of AT progression.

Aged↗
PubMed2005

Predictors of atrial antitachycardia pacing efficacy in patients affected by brady-tachy form of sick sinus syndrome and implanted with a DDDRP device.

UNLABELLED: Predictors of ATP efficacy in brady/tachy patients. BACKGROUND: Recent options to treat atrial tachyarrhythmias (ATA) include implantable devices delivering antitachycardia pacing therapies (ATP). No prospective study selected patients with higher chances of episode termination by ATP or indicated the most effective ATP use. Our aim was to study ATP efficacy in patients with brady-tachy form of sinus node disease (SND), identifying clinical factors, ATA characteristics, and device features predicting ATP efficacy. METHODS AND RESULTS: Three hundred and sixteen patients (105 M, aged 71.1+/-8.8 years) received a DDDRP pacemaker and were prospectively followed. Median follow-up was 18 months: 37,125 ATA episodes occurred in 217 patients; ATP treated 5,536 of them. Overall, ATP efficacy was 50.0%. A multivariate analysis identified longer arrhythmia cycle lengths (OR=1.25; CI=1.07-1.47) and shorter delays to ATP delivery (OR=0.15; CI=0.10-0.22) as independent predictors of ATP efficacy for episodes preceded by >or=5 minutes of sinus rhythm. Additionally, ATP efficacy for all treated episodes was predicted by lower New York Heart Association (NYHA) class (OR=0.64; CI=0.42-0.98), episode classification as nonimmediate recurrence of ATA (non-IRAT) (OR=0.07; CI=0.02-0.33), absence of overlap in the device detection windows (OR=0.54; CI=0.32-0.91), and flecainide treatment (OR=2.22; CI=1.04-4.71). CONCLUSIONS: In patients paced for SND, multivariate analysis shows that ATP efficacy is associated to longer arrhythmia cycle lengths, shorter ATP delivery delays, NYHA class I, episode classification as non-IRAT, absence of overlap in the atrial arrhythmia device detection windows, and flecainide treatment.

Aged↗
PubMed2005

Electrical cardioversion of atrial fibrillation: different methods for a safe and effective technique.

Atrial fibrillation is the most common cardiac arrhythmia observed in clinical practice. Many different therapeutic approaches are available at present but none may be considered the gold standard treatment. Antiarrhythmic drugs are not very effective agents to cardiovert persistent atrial fibrillation and, therefore, the technique most frequently used to restore sinus rhythm is external direct current cardioversion, which has proved to be safe and very effective. Esophageal cardioversion is an alternative method that could obviate some of the limitations of the external technique, such as the high energy required, need for anesthesia and longer hospital stay. Another technique performed during the last two decades is internal cardioversion, but at present, the advantage of this technique is limited to the small proportion of cases of unsuccessful external cardioversion.

Atrial Fibrillation↗
PubMed2005

The role of the implantable atrial cardioverter-defibrillator.

Atrial and dual-chamber defibrillators with atrial antitachycardia functions represent an emerging option for the treatment of patients with drug-refractory atrial fibrillation. Atrial cardioversion has been demonstrated to be highly effective in treating spontaneous tachyarrhythmias and may reduce atrial fibrillation burden by preventing atrial remodeling. Device implantation has been associated with an improved quality of life and a reduced hospitalization rate. Patient selection and tailored device programming are critical as regards clinical outcome. The individual psychological profile analysis as well as the underlying heart disease and clinical patterns of atrial fibrillation represent the main drivers for the right strategy. Controlled studies are needed in order to define the subset of patients who can benefit more from device implantation.

Atrial Fibrillation↗
PubMed2005

Stem cell therapy for cardiac arrhythmias.

Clinical studies suggest that stem cell transplantation (SCT) is feasible and has the potential for beneficial effects in several cardiac affections, including myocardial infarction and advanced heart failure. However, concern exists about the possible occurrence of serious arrhythmias after SCT, even if such complication has been shown only in case of skeletal myoblast transplantation. SCT might induce arrhythmias by several mechanisms, such as electrotonic stimulation of cardiac cells, electrical heterogeneity of action potentials during stem cell differentiation process, increased nerve sprouting, and local tissue injury induced by intramyocardial injection. As a matter of fact, the use of endothelial progenitor cells from the peripheral blood or of stem cells from bone marrow has not been associated with any significant cardiac rhythm disturbance. Recently, a new opportunity for SCT has emerged: the development of a biological cardiac pacemaker. Both gene therapy and cell therapy have been used in this new perspective. In fact, at present, the transformation of a normal cardiomyocyte in a pacemaker cell can be obtained in animal models by the injection of a plasmid or virus, incorporating the gene encoding for specific proteins. This procedure transforms cardiomyocytes in transgenic cells that may show an overexpression of beta2-adrenergic receptors, or abnormal membrane ion channels. As an alternative, genetically modified mesenchymal stem cells can be delivered within the heart and engraft to develop a biological pacemaker. To date, several studies have been performed in different animal models employing both cell and gene therapy. However, complex problems concerning safety and efficacy require a solution before we can move to the step of clinical evaluation in human beings.

Arrhythmias, Cardiac↗
PubMed2005

Atrial flutter and atrial fibrillation: which relationship? New insights into the electrophysiological mechanisms and catheter ablation treatment.

Atrial fibrillation (AF) and atrial flutter (AFL) are two arrhythmias commonly associated in clinical practice. This association generally reflects a similar arrhythmogenic substrate. It has been observed that the development of isthmus-dependent AFL is often preceded by AF. The conversion from AF to AFL develops thanks to a line of functional block in the right atrial free wall. In this subset a particular condition is represented by typical AFL that occurs during the treatment with class IC or III antiarrhythmic drugs in patients with previous AF. A hybrid approach (antiarrhythmic drugs and catheter ablation) has been proposed as a possible treatment of drug-induced AFL. The conversion from AFL to AF is less frequent and may be due to several mechanisms: a shortening of the length of the line of functional block, atrial ectopic beats or rapid atrial rhythm, focal activation from the pulmonary veins, alternans of atrial action potentials. Also, atypical right and left AFL can determine AF. Finally, atypical AFL may occur after AF ablation, and could be prevented by associated cavotricuspid isthmus ablation.

Animals↗
PubMed2005

Recovery of cardiac function after ablation of atrial tachycardia arising from the tricuspid annulus.

Tachycardia-induced cardiomyopathy is a reversible form of heart failure. An early diagnosis and an effective cure of the underlying tachycardia are crucial for a favorable outcome. Different kinds of atrial and ventricular arrhythmias may induce tachycardiomyopathy. Focal atrial tachycardia may be easily suppressed by means of transcatheter ablation. Relationships between focal atrial tachycardia and tachycardiomyopathy have not been deeply analyzed. In the present paper we report a case of a 76-year-old man with tachycardia-induced cardiomyopathy caused by recurrences of focal atrial tachycardia arising from the tricuspid annulus. The arrhythmia was successfully treated with transcatheter ablation. In the follow-up no recurrences of the arrhythmia occurred and a significant improvement in myocardial function was observed.

Aged↗
PubMed2005

[Deleterious effects of apical right ventricular stimulation. Should we change our standard method of pacemaker implantation?].

Up to now the apical right ventricle one is the best pacemaker implantation. As a matter of fact this site is easily reachable by catheter and dislocations are few. Nevertheless evidence from the literature demonstrates dyssynchrony in myocardial contraction pattern, diastolic dysfunction and mismatch in perfusion and innervation. For this reason alternative sites of stimulation have been tested. One of these is represented by the right ventricular outflow tract. Some studies have compared this site to the apical one, showing a better cardiac index in the former; moreover QRS was narrower and fewer perfusional defects have been found. On the contrary, other studies did not show any significant differences between these two sites of stimulation. In order to obtain cardiac resynchronization, biventricular pacing, has been introduced, consisting in the contemporary stimulation of the lateral wall of both ventricles from a cardiac vein, originating from the coronary sinus. It has been proposed a bifocal stimulation, in which we introduce one catheter into the apex and another one in the right ventricular outflow tract: in this case QRS complex is narrower but cardiac output is not increased. A newer pacing technique is represented by direct His bundle stimulation. We can obtain a narrow QRS complex, like the physiological one. So we might solve problems related to intraventricular dyssynchrony.

Cardiac Output↗
PubMed2005

A complete atrioventricular block secondary to myocardial metastases of lung cancer. A case report.

A metastatic involvement of the heart is an uncommon phenomenon in clinical practice; it is more frequent in patients with end-stage disease and a wide tumor spread. The clinical diagnosis is very difficult because there are no early symptoms and most often, the presence of metastases in other sites, such as lung and lymph nodes, may determine a misunderstanding of the clinical picture. We report the case of a young male (44 years old) with a complete atrioventricular block due to metastatic myocardial involvement from a primary occult lung cancer. The first symptom of the disease was a syncopal spell. In spite of permanent pacemaker implantation, the patient died suddenly and unexpectedly after 3 days. Autopsy revealed an anaplastic carcinoma of the right lung hilus. The myocardium was invaded by numerous metastatic nodules, particularly in the interventricular septum and in the left ventricular wall.

Adult↗
PubMed2004

Temporal variability of atrial tachyarrhythmia burden in bradycardia-tachycardia syndrome patients.

AIMS: Several studies have tested non-pharmacological therapies for atrial tachyarrhythmias (ATs) by measuring the cumulative time (burden) the patient spends in arrhythmia. Contradictory results questioned either therapy efficacy or statistical power of the trials. We studied AT burden variability in patients paced for sinus node disease (SND) in order to interpret currently published data appropriately and to evaluate reliable sample sizes. METHODS AND RESULTS: One hundred and five patients with AT and SND received a dual chamber pacemaker with antitachyarrhythmia-pacing capability, and were followed for 13 months. Seventy-eight patients (74%) suffered AT recurrences. Device-gathered diagnostic measures were used to simulate results of randomized studies both with crossover and parallel design. The sample size required for statistically significant results was calculated as a function of the expected therapy-induced burden reduction. AT burden intra-patient variability was high: 43% of patients showed intrinsic fluctuations hiding any therapy-induced burden reduction lower than 30%. Demonstrating therapeutic breakthrough through a 6 month study would require 290 patients with crossover design and 5800 patients with parallel design. Doubling the study period requires 400 and 3000 patients, respectively. CONCLUSION: Patients with AT and paced for SND showed high intra-patient burden variability, which could possibly hide an AT burden reduction induced by a therapy. Previous studies involving non-pharmacological therapies utilizing AT burden endpoints could lack the power to reach statistical significance.

Aged↗
PubMed2004

Cardiac autonomic derangement and arrhythmias in right-sided stroke with insular involvement.

BACKGROUND AND PURPOSE: The insula of the right cerebral hemisphere may have a major role in cardiac autonomic control. This study was aimed at assessing the effects of acute right insular ischemic damage on heart rate variability (HRV) and arrhythmias. METHODS: Holter monitoring for 24 hours was performed in 103 consecutive patients with first-ever acute ischemic stroke. Time and frequency domain measures of HRV and arrhythmias were considered in all cases. RESULTS: Forty-nine patients (47.5%) had a right-sided infarction, whereas 54 (52.5%) had a left-sided infarction. Insular involvement was present in 33 patients with right-sided stroke (67.3%) and in 36 patients with left-sided stroke (66.6%). When compared with all other stroke patients, subjects with right-sided insular damage showed significantly lower values of the standard deviation of all normal-to-normal (SDNN) R wave to R wave (RR) intervals and of the root mean square of differences (rMSSD) of adjacent normal-to-normal RR intervals, and higher low-frequency/high-frequency ratio values (P<0.05). Right insular stroke was also associated with more complex arrhythmias than any other localization (P<0.05). Moreover, in the whole population of stroke patients, lower values of SDNN were associated with the presence of more frequent and complex arrhythmias. CONCLUSIONS: These findings further support the notion that the right insula is implicated in the autonomic control of cardiac activity and that acute right insular damage may lead to a derangement of cardiac function with potential prognostic implications.

Aged↗
PubMed2004

Epidemiology and prognostic implications of syncope in young competing athletes.

AIMS: This study was undertaken to evaluate the epidemiological features and the prognostic implications of syncope in young athletes. METHODS AND RESULTS: A cohort of 7568 young athletes (5132 males, 2436 females, aged 16.2 +/- 2.4) underwent a pre-participation evaluation. A syncopal spell in the last 5 years was reported by 474 athletes (6.2%). Syncope was unrelated with exercise in 411 athletes (86.7%), post-exertional in 57 (12.0%) and exertional in 6 (1.3%). All episodes of non-exertional or post-exertional syncope had the typical features of neurally-mediated fainting. The 6 athletes with exertional syncope underwent further testing allowing the diagnosis of hypertrophic cardiomyopathy in one case, and of right ventricular outflow tract tachycardia in another. The remaining 4 athletes only showed a positive response to tilt-testing. All athletes were followed for 6.4 +/- 3.1 years, during 48,066.6 person-years of follow-up. The recurrence rate was 20.3 per 1000 subject-years in athletes with non-exertional, and 19.2 per 1000 subject-years in athletes with post-exertional syncope. The incidence of first report of syncope was 2.2 per 1000 subject-years for non-exertional and 0.26 per 1000 subjects-years for post-exertional spells. No other adverse event was noted during follow-up. CONCLUSIONS: In young athletes, syncope occurring before the initial pre-participation screening has a neurally-mediated origin in most cases and shows a low recurrence rate. Exercise-related syncope is infrequent and is not associated with an adverse outcome in subjects without cardiovascular abnormalities. The incidence of new syncope during competitive activity is particularly low.

Adolescent↗
PubMed2004

Triple-site pacing in patients with biventricular device-incidence of the phenomenon and cardiac resynchronization benefit.

BACKGROUND: In patients with biventricular pacing (BIV), triple-site pacing (TSP), i.e. standard biventricular cathodal pacing of the right and the left ventricle plus additional anodal capture of the right ventricle, is sometimes present. AIMS: To evaluate the incidence of TSP phenomenon, to examine TSP-related QRS changes, and to assess the effect of TSP on intraventricular resynchronization by means of tissue Doppler imaging (TDI). METHODS AND RESULTS: 23 patients with a first generation biventricular device (Medtronic 8040) and 16 patients with a new generation device (Medtronic 8042) were evaluated to look for the presence of TSP. TSP was found in 6 patients (26%) with the Medtronic 8040 (group I) and in 13 patients (81%) with the Medtronic 8042 device (group II). QRS duration decreased by 10 to 20 ms and QRS amplitude of leads I and aVL increased in almost all patients in group I during TSP modality. In group II, QRS morphology, duration and amplitude did not change as obviously. TDI analysis of the left ventricular (LV) basal segments showed significant shortening of the systole, together with a corresponding prolongation of the diastole, at the inferior wall of the LV, during TSP compared to standard BIV in all patients ( p < 0.01). Other LV segments did not show any change. Qualitative TDI electro-mechanical activation pattern of all LV segments improved in 22%, while it remained unchanged in 72%. CONCLUSIONS: TSP phenomenon can be identified in approximately a quarter of patients with the first-generation biventricular devices on the basis of the QRS morphology changes. In the second-generation biventricular pacemakers it can be demonstrated in the vast majority of patients. TSP may increase the effectiveness of cardiac resynchronization therapy by counteracting the regional activation delay located at the inferior wall of the LV.

Aged↗
PubMed2004

Dual defibrillator improves quality of life and decreases hospitalizations in patients with drug refractory atrial fibrillation.

AIM OF THE STUDY: to evaluate the impact of dual defibrillator implantation on quality of life and resource utilization in patients with drug refractory atrial fibrillation (AF) without prior ventricular arrhythmias. METHODS: Forty patients (28 M, mean age 64 +/- 10) received a dual defibrillator Medtronic 7250. AF was persistent in 60% and paroxysmal in 40%. RESULTS: The follow-up lasted 15 +/- 4 months (range 12-30). Eighty-five percent of patients had atrial tachyarrhythmia recurrences. Among 1366 treated episodes, overall success rate was 60.1% for antitachy pacing and 88.2% for atrial shock. Within one year after implant, arrhythmia related hospitalization number decreased from 1.5 +/- 2.0 to 0.4 +/- 0.8 ( p < 0.01) and 77% of patients were free from hospitalization. As regard to quality of life, Symptom Checklist/Frequency and Severity Scale improved after implant for all items and SF-36 questionnaire showed significant improvements in physical activities because of health problems and social activities. The patients assigned to early delivery of atrial shock after AF onset, when compared with the patients who did not accept atrial shock, showed a significant reduction of AF burden, a higher reduction of hospitalization number and a greater improvement of quality of life. CONCLUSION: Dual defibrillator improved quality of life and decreased resource utilization in patients with drug refractory AF. Early delivering of atrial shock seems to be the most effective option.

Aged↗
PubMed2004

Long-term follow-up of right atrial ablation in patients with atrial fibrillation:.

INTRODUCTION: The aim of this study was to evaluate the efficacy and the impact on quality of life of a new ablative approach to the right atrium in patients with atrial fibrillation (AF). METHODS AND RESULTS: Seventy-four symptomatic patients with paroxysmal (n = 49) or permanent (n = 25) refractory AF underwent radiofrequency ablation. A nonfluoroscopic electroanatomic mapping system was used to perform the following lesions: (1) an isthmus line between the tricuspid annulus and the inferior vena cava; (2) a posterior intercaval line from the superior vena cava and the inferior vena cava; (3) a septal line from the superior vena cava to the fossa ovalis, proceeding to the coronary sinus ostium where a circumferential line around the ostium was performed, and then on to the inferior vena cava; and (4) a transversal lesion connecting the posterior intercaval and the septal lesions. In addition, electrical disconnection of the superior vena cava was performed. There were no complications. Postablation remapping showed the absence of discrete electrical activity inside and just around the ablation lines. Electrical disconnection of the superior vena cava was obtained in all patients. After 21 +/- 6 months, 49 patients (66%) had stable sinus rhythm with continuation of the previous antiarrhythmic drug therapy, 13 patients (18%) were considered improved, and 12 (16%) received no benefit (unsuccessful procedure). After ablation, quality of life was significantly improved, reaching the levels of the general Italian population. Ejection fraction and the extent of the low-voltage area were found by multivariate analysis to be independent predictors of AF recurrence. CONCLUSION: The results of the present study suggest that this ablative approach in combination with antiarrhythmic drugs is safe and effective in treating AF, leading to a marked increase in quality of life in patients with refractory AF.

Atrial Fibrillation↗
PubMed2004

Atrial tachyarrhythmia recurrence temporal patterns in bradycardia patients implanted with antitachycardia pacemakers.

INTRODUCTION: New-generation pacemakers allow continuous atrial tachyarrhythmia (AT) monitoring that provides accurate information about AT type, frequency, burden, and temporary evolution. METHODS AND RESULTS: We performed a prospective multicenter study to describe AT temporal patterns in patients with sinus bradycardia and AT. Two hundred forty patients (123 men; age 71 +/- 8 years) were implanted with a DDDRP pacemaker (model AT500, Medtronic Inc.). All patients were followed for 13 months. The first-month stabilization period of all patients was discarded from analysis. Seventy percent of patients had AT recurrences. Mean time to first AT recurrence (48.2 days, 95% confidence interval [CI] 37.0-59.5 days) was significantly longer than the time between first and second AT episode (10.3 days, 95% CI 6.7-13.9 days, P < 0.01). A minority of patients had a uniform time distribution of AT recurrences: <25% of patients had AT episodes in more than 6 of the 12 months considered in the study. The probability density function of consecutive sinus rhythm days between AT episodes was calculated for each of 40 patients who experienced >25 AT episodes and fitted by power law and exponential functions. The best fit was obtained by power law function in 60% of patients, by exponential function in 10%, and the two models gave comparable results in 30% of patients. CONCLUSION: In our population of patients with a history of sinus bradycardia and AT who were implanted with a new device equipped with atrial pacing therapies, 30% did not experience AT recurrences in the 12-month study period. Analysis of interevent time showed that in 60% of patients AT recurrences do not follow a uniform or random distribution. These findings bring into question the use of cross-over design and time to first AT recurrence as a clinical outcome in trials for AT therapy in this patient population.

Adult↗