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Biomedical subjects

A Natale

Publications and source records attributed to A Natale.

At least 37 records · Page 2Linked to original sources
PubMed2000

Prospective randomized comparison of antiarrhythmic therapy versus first-line radiofrequency ablation in patients with atrial flutter.

BACKGROUND: Despite the high success rate of radiofrequency (RF) ablation, pharmacologic therapy is still considered the standard initial therapeutic approach for atrial flutter. OBJECTIVE: We prospectively compared the outcome at follow-up of patients with atrial flutter randomly assigned to drug therapy or RF ablation. METHODS: Patients with at least two episodes of symptomatic atrial flutter in the last four months were randomized to regimens of either antiarrhythmic drug therapy or first-line RF ablation. After institution of therapy, end points included recurrence of atrial flutter, rehospitalization and quality of life. RESULTS: A total of 61 patients entered the study, 30 of whom were randomized to drug therapy and 31 to RF ablation. After a mean follow-up of 21 +/- 11 months, 11 of 30 (36%) patients receiving drugs were in sinus rhythm, versus 25 of 31 (80%) patients who underwent RF ablation (p < 0.01). Of the patients receiving drugs, 63% required one or more rehospitalizations, whereas post-RF ablation, only 22% of patients were rehospitalized (p < 0.01). Following RF ablation, 29% of patients developed atrial fibrillation which was seen in 53% of patients receiving medications (p < 0.05). Sense of well being (pre-RF 2.0 +/- 0.3 vs. post-RF 3.8 +/- 0.5, p < 0.01) and function in daily life (pre-RF 2.3 +/- 0.4 vs. post-RF 3.6 +/- 0.6, p < 0.01) improved after ablation, but did not change significantly in patients treated with drugs. CONCLUSION: In a selected group of patients with atrial flutter, RF ablation could be considered a first-line therapy due to the better success rate and impact on quality of life, the lower occurrence of atrial fibrillation and the lower need for rehospitalization at follow-up.

Aged↗
PubMed2000

False positive head-up tilt: hemodynamic and neurohumoral profile.

OBJECTIVES: This study examined differences in mechanisms of head-up tilt (HUT)-induced syncope between normal controls and patients with neurocardiogenic syncope. BACKGROUND: A variable proportion of normal individuals experience syncope during HUT. Differences in the mechanisms of HUT-mediated syncope between this group and patients with neurocardiogenic syncope have not been elucidated. METHODS: A 30-min 80 degrees HUT was performed in eight HUT-negative volunteers (Group I), eight HUT-positive volunteers (Group II) and 15 patients with neurocardiogenic syncope. Heart rate and blood pressure (BP) were monitored continuously. Epinephrine and norepinephrine plasma levels, as well as left ventricular dimensions and contractility determined by echocardiography, were measured at baseline and at regular intervals during the test. RESULTS: The main findings of this study were the following: 1) All parameters were similar at baseline in the three groups; and 2) During tilt: a) the time to syncope was shorter in Group III than in group II (9.5 +/- 3 vs. 17 +/- 3 min p < 0.05); b) there was an immediate, persisting drop in mean BP in Group III; c) the decrease rate of left ventricular end-diastolic dimensions was greater in Group III than in Group II or Group I (-1.76 +/- 0.42 vs. -0.87 +/- 0.35 and -0.67 +/- 0.29 mm/min, respectively, p < 0.05); d) the leftventricular shortening fraction was greater in Group III than in the other two groups (39 +/- 1 vs. 34 +/- 1 and 32 +/- 1%, respectively, p < 0.05); and e) although the norepinephrine level remained comparable among the groups, there was a significantly higher peak epinephrine level in Group III than in Group II and Group I (112.3 +/- 34 vs. 77.6 +/- 10 and 65 +/- 12 pg/ml, p < 0.05). CONCLUSIONS: Mechanisms of syncope during HUT appeared to be different in normal volunteers and patients with neurocardiogenic syncope. In the latter, there was evidence of an impaired vascular resistance response from the beginning of the orthostatic challenge. Furthermore, in the patients there was more rapid peripheral blood pooling, as indicated by the echocardiographic measurements of left ventricular end-diastolic changes, leading to more precocious symptoms. In syncopal patients, the higher level of plasma epinephrine probably mediated the increased cardiac contractility and possibly contributed to the impaired vasoconstrictive response.

Adult↗
PubMed2000

Catheter ablation approach on the right side only for paroxysmal atrial fibrillation therapy: long-term results.

We report the long-term follow-up of a right side only catheter ablation approach for paroxysmal AF. Eighteen patients with AF refractory to drugs entered the study. Ablation was attempted in the right atrium only by creating linear lesions based on a specific design including from two to four linear lesions. Induction of AF was attempted before ablation and after placement of the lesions. A septal lesion was performed in nine patients. In ten patients atrial defibrillation thresholds (ADFTs) before ablation and following creation of the linear lesions were compared. After a mean follow-up of 22 +/- 11 months, seven patients had recurrence of AF, and another nine patients experienced atrial flutter or atrial tachycardia. Five patients remained in sinus rhythm without medications and four required the use of drugs. Three patients had sporadic AF and six were in chronic AF. The recurrence rate was similar in patients with and without the septal lesion. However, a cure with right side ablation appeared to be predicted by the presence of disorganized and earlier activity in the high right atrium and crista terminalis. Linear lesions in the right atrium were associated with a lower ADFT (pre 2.6 +/- 04 J vs post 1.7 +/- 0.6 J). In conclusion, in a small number of patients, control of AF can be obtained with a right side only approach. Certain activation patterns may identify patients suitable to this approach. No specific lesion pattern appeared more effective. Right atrial linear lesions resulted in lower ADFT.

Atrial Fibrillation↗
PubMed2000

Radiofrequency ablation of a right atrial appendage-ventricular accessory pathway by transcutaneous epicardial instrumentation.

Epicardial location of accessory AV pathways may be responsible for the failure of conventional endocardial radiofrequency catheter ablation. Transcutaneous epicardial instrumentation provides access to the normal pericardium with no need for invasive thoracotomy or thoracoscopy. We report the case of successful epicardial mapping and ablation of a right atrial appendage-ventricular connection using a percutaneous epicardial approach, after repeated failure of endocardial ablation attempts.

Adult↗
PubMed1999

AV node ablation and pacemaker implantation after withdrawal of effective rate-control medications for chronic atrial fibrillation: effect on quality of life and exercise performance.

We assess whether AV node ablation and pacemaker implantation after discontinuation of effective rate-control medical therapy for chronic atrial fibrillation had a positive impact on quality of life and exercise performance. To assess the possibility of a placebo effect following pacemaker implantation, the study included three groups of patients. Group 1 underwent an echocardiogram, treadmill exercise, and quality of life measurement 1 month prior to and 6 months following AV node ablation and pacemaker implantation associated with discontinuation of rate-control medications. Group 2 underwent AV node ablation and pacemaker implantation without discontinuation of antiarrhythmic rate-control drugs. Group 3 underwent pacemaker implantation without performing AV node ablation and continuing rate-control medical therapy. At the 1- and 6-month evaluation, the patients in group 1 showed a significant improvement of left ventricular ejection fraction, quality of life, and activity scores. The exercise duration and the maximal VO2 consumption, however, did not change significantly. A slight improvement of the quality of life and physical activity scores was observed in the group undergoing AV node ablation without withdrawal of medications. However, no significant changes were observed in the group receiving only the pacemaker without modification of medical therapy and with intact AV node conduction. In conclusion, in patients with chronic atrial fibrillation, discontinuation of effective rate-control medical therapy followed by AV node ablation and permanent pacing appeared to improve quality of life and activity scores despite no change in exercise duration. The improvement observed does not seem to reflect a placebo effect.

Aged↗
PubMed1999

Epicardial mapping and radiofrequency catheter ablation of ischemic ventricular tachycardia using a three-dimensional nonfluoroscopic mapping system.

Endocardial radiofrequency catheter ablation of ischemic left ventricular tachycardia has been of variable success due to multiple factors. Two such factors include the location of the reentrant circuit in the deep myocardium or on the epicardial surface and the inherent limitations of fluoroscopy as a guide for target localization. We report a patient in whom successful epicardial mapping and radiofrequency catheter ablation of an ischemic left ventricular tachycardia was performed using pericardial access and the CARTO electroanatomic mapping system.

Aged↗
PubMed1999

Human histopathologic findings following radiofrequency ablation of the tricuspid-inferior vena cava isthmus.

Radiofrequency (RF) ablation of the tricuspid valve-inferior vena cava isthmus is now the first line of treatment in the management of typical atrial flutter. Successful ablation is associated with conduction block in this region, although the histopathologic changes following this procedure have never been reported. We describe the pathologic changes following RF ablation of this region in an explanted heart of a patient undergoing heart transplantation 4 months after successful atrial flutter ablation. The findings confirm the ability of RF ablation to create in the isthmus a chronic full thickness fibrosis, which represents the histopathologic counterpart of the conduction block demonstrated at the end of procedure.

Atrial Flutter↗
PubMed1999

[Acute epiglottitis in children: current criteria for the diagnosis and treatment].

Acute epiglottitis is still a potentially lethal pathology, particularly in early childhood. The present study involves seven cases of acute epiglottitis in children under 4 years of age. The authors describe the diagnostic and therapeutic protocols used in these pediatric patients placing particular emphasis on the use of endoscopy and the need for prompt hospitalization in an intensive care unit to best integrate the diagnostic approach with therapeutic treatment.

Acute Disease↗
PubMed1998

Sustained ventricular arrhythmias in patients receiving thrombolytic therapy: incidence and outcomes. The GUSTO Investigators.

BACKGROUND: Sustained ventricular tachycardia (VT) and fibrillation (VF) occur in up to 20% of patients with acute myocardial infarction (MI) and have been associated with a poor prognosis. The relationships among the type of arrhythmia (VT versus VF or both), time of VT/VF occurrence, use of thrombolytic agents, and eventual outcome are unclear. METHODS AND RESULTS: In the GUSTO-I study, we examined variables associated with the occurrence of VT/VF and its impact on mortality. Of the 40 895 patients with ventricular arrhythmia data, 4188 (10.2%) had sustained VT, VF, or both. Older age, systemic hypertension, previous MI, Killip class, anterior infarct, and depressed ejection fraction were associated with a higher risk of sustained VT and VF (P<0.001). In-hospital and 30-day mortality rates were higher among patients with sustained VT/VF than among patients without sustained ventricular arrhythmias (P<0.001). Both early (<2 days) and late (>2 days) occurrences of sustained VT and VF were associated with a higher risk of later mortality (P<0. 001). In addition, patients with both VT and VF had worse outcomes than those with either VT or VF alone (P<0.001). Among patients who survived hospitalization, no significant difference was found in 30-day mortality between the VT/VF and no VT/VF groups. However, after 1 year, the mortality rate was significantly higher in the VT alone and VT/VF groups (P<0.0001). CONCLUSIONS: Despite the use of thrombolytic therapy, both early and late occurrences of sustained VT or VF continue to have a negative impact on patient outcome; patients with both VT and VF had the worst outcome; and among patients who survived hospitalization, the 1-year mortality rate was significantly higher in those who experienced VT alone or VT and VF.

Administration, Cutaneous↗
PubMed1998

Use of sublingual nitroglycerin during head-up tilt-table testing in patients >60 years of age.

Previous work had demonstrated a reduced specificity associated with head-up tilt protocols using high-dose isoproterenol in patients between 20 and 50 years of age. We evaluated the specificity of head-up tilt testing using different isoproterenol infusion doses and administration of nitroglycerin in patients aged >60 years. In addition, whether the same protocols have impact on the sensitivity of the test was also assessed. One hundred sixty subjects were included in this study. Seventy-six were volunteers randomized to either head-up tilt test with low-dose, 3- and 5-microg/min of isoproterenol (group I) or to a protocol including 0.4 mg of sublingual nitroglycerin (group II). In addition, after an upright tilt drug-free state, 58 patients with a history of syncope underwent repeat head-up tilt with increasing doses of isoproterenol infusion, followed by sublingual nitroglycerin if the test result remained negative. The remaining 33 patients were subjected to the nitroglycerin protocol after the drug-free state phase. In the control groups, the incidence of false-positive responses was 88% and 95%, respectively. In patients with syncope after a negative test result during 5 microg of isoproterenol infusion, nitroglycerin administration increased the number of positive responses from 45% to 79%. The percentage of positive tilt in patients undergoing nitroglycerin administration after the drug-free state part of the protocol was 78%. Administration of nitroglycerin was the most significant predictor of a positive upright tilt in patients with syncope. In subjects aged >60 years, head-up tilt protocols with high-dose isoproterenol infusion and nitroglycerin maintained an adequate specificity. In this subset of patients, nitroglycerin seemed to provide a better sensitivity than isoproterenol.

Administration, Sublingual↗
PubMed1998

QT prolongation and dispersion in myocardial ischemia and infarction.

The ability of QT interval dispersion to predict the occurrence of ventricular fibrillation (VF) after acute myocardial infarction treated with thrombolytic therapy is controversial. Continuous 12-lead electrocardiographic (ECG) monitoring for 48 hours or longer provides an opportunity to detect transient changes of QT dispersion and correlate such changes with the clinical outcome. In 543 consecutive patients enrolled in the TAMI-9 and GUSTO I studies, serial changes of the QT dispersion were analyzed in an attempt to predict the occurrence of VF with a system that monitored continuously the 12-lead ECG and stored it at least every 20 minutes. Measurements of QT dispersion were made at a median time of 2.37 hours after the onset of chest pain and at 24- and 48-hour intervals. A total of 43 patients experienced VF during the acute phase of myocardial infarction; of these patients, 33 (77%) had anterior infarcts. However, despite the higher preponderance of anterior myocardial infarcts in the VF group, patients with anterior infarcts did not have longer QT dispersion than those with other infarct locations. Similarly, no significant differences in the QT dispersion were observed at any time between the group with VF and that without. Women had increased QT dispersion in the initial and 24-hour ECG as compared with men (P = .005). However, this normalized at the 48-hour measurements. Despite this difference, there was no higher incidence of VF in female patients. In conclusion, the data suggest that QT dispersion alone is not sufficient to explain the occurrence of VF in the acute phase of myocardial infarction after thrombolytic therapy.

Electrocardiography↗
PubMed1998

Impaired vasorelaxant responses to natriuretic peptides in the stroke-prone phenotype of spontaneously hypertensive rats.

BACKGROUND: We have previously shown that a locus on rat chromosome 5, termed STR 2, co-localizes with the genes encoding atrial natriuretic and brain natriuretic peptides, and is closely linked to the development of strokes in rats of a F2 hybrid cohort obtained by crossing stroke-prone spontaneously hypertensive rats and spontaneously hypertensive rats. We also demonstrated that there are significant differences in vascular functioning that are co-segregated with stroke latency of stroke-prone spontaneously hypertensive rats. OBJECTIVE: To investigate the vascular responses to natriuretic peptides in the stroke-prone phenotype of spontaneously hypertensive rats. DESIGN AND METHODS: In view of the important vasoactive properties of natriuretic peptides, we tested the vascular responses to 10(-11)-10(-9) mol/l atrial natriuretic peptide and to 10(-11)-10(-7) mol/l brain natriuretic peptide in isolated rings of aortas and internal carotid arteries obtained from stroke-prone and stroke-resistant spontaneously hypertensive rats. The 6-week-old rats were exposed for 4 weeks either to their regular diet (n = 15 of both strains) or to the stroke-permissive Japanese-style diet (n = 14 of both strains). A group of 14 normotensive, age-matched and sex-matched Wistar-Kyoto rats was also studied. RESULTS: Systolic blood pressures in stroke-prone and stroke-resistant spontaneously hypertensive rats were similar, and were significantly higher than those in Wistar-Kyoto rats. Vascular responses to nitroglycerin, atrial natriuretic peptide, and brain natriuretic peptide in rats of the two hypertensive strains and in Wistar-Kyoto rats fed their regular diet were comparable. In contrast, the vasorelaxant responses to atrial natriuretic peptide in stroke-prone spontaneously hypertensive rats fed Japanese diet were lower both in aortas and in internal carotid arteries than were those in spontaneously hypertensive rats (both P < 0.05 by analysis of variance) and in Wistar-Kyoto rats (both P < 0.05). Similarly, vasorelaxant responses to brain natriuretic peptide were lower both in aortas and in internal carotid arteries of stroke-prone spontaneously hypertensive rats than they were in spontaneously hypertensive rats (both P < 0.05) and in Wistar-Kyoto rats (P < 0.05). The responses to nitroglycerin in the stroke-prone spontaneously hypertensive rats and spontaneously hypertensive rats fed Japanese-style diet were also similar. CONCLUSION: The vasorelaxant effects of natriuretic peptides are impaired in stroke-prone spontaneously hypertensive rats. This abnormality could play a role in the pathogenesis of stroke incidence in this hypertensive model.

Animals↗
PubMed1998

Role of the angiotensin II AT2-subtype receptors in the blood pressure-lowering effect of losartan in salt-restricted rats.

OBJECTIVE: The aim of this study was to evaluate the potential role of the angiotensin II (Ang II) AT2 receptors (AT2) in the control of blood pressure (BP) in the rat and the effects of AT2 receptors on BP during AT1 receptor (AT1) antagonism. METHODS: The study was performed in 52 Sprague-Dawley rats, which were preliminarily salt-restricted (SR) to enhance circulating and tissue renin-angiotensin system activity. To explore whether AT2 plays a role in BP regulation, the BP effects of the selective AT2 and AT1 receptor antagonists PD123319 (PD) (50 microg/kg/min) and losartan (Los) (10 mg/kg/day), were studied. Seven rats were used as a control group. To define whether AT2 plays a role in the BP response observed during AT1 antagonism, 17 Los treated rats were divided into two groups: seven were treated with both antagonists (Los + PD) and 10 rats received Los + vehicle. The effects of both drugs were also studied in bilaterally nephrectomized rats (NX). All treatments were maintained for 1 week RESULTS: Los reduced BP significantly in both intact (P < 0.001) and NX (P < 0.05) rats, while PD increased BP in intact and NX rats (both P < 0.001). In the Los + PD group BP levels were significantly higher (P < 0.001 vs Los and Los + vehicle, P = ns vs pretreatment), while vehicle infusion did not modify the BP response to Los. CONCLUSION: The results show that in salt-restricted rats AT2 blockade offsets the BP-lowering effect of losartan and suggest that AT2 receptors contribute to the hypotensive effects of losartan. Thus, AT1 receptor antagonists such as losartan, which are becoming widely used in the clinical treatment of hypertension, may reduce BP not only by blockade of AT1 receptors, but also through the stimulation of AT2 receptors by the excess of angiotensin II.

Angiotensin II↗