ABSTRACT
AIM: To assess the effectiveness of cardiac resynchronisation therapy (CRT), implantable cardioverter defibrillator (ICD) therapy, and the combination of these devices (CRT+ICD) in adult patients with left ventricular dysfunction and symptomatic heart failure. METHODS: A comprehensive systematic review of randomised clinical trials was conducted. Several electronic databases (PubMed, Embase, Ovid, Cochrane, ClinicalTrials.gov) were reviewed. The mortality rates between treatments were compared. A network was established comparing the various options, and direct, indirect and mixed comparisons were made using multivariate meta-regression. The degree of clinical and statistical homogeneity was assessed. RESULTS: 43 trials involving 13â 017 patients were reviewed. Resynchronisation therapy, defibrillators, and combined devices (CRT+ICD) are clearly beneficial compared to optimal medical treatment, showing clear benefit in all of these cases. In a theoretical order of efficiency, the first option is combined therapy (CRT+ICD), the second is CRT, and the third is defibrillator implantation (ICD). Given the observational nature of these comparisons, and the importance of the overlapping CIs, we cannot state that the combined option (CRT+ICD) offers superior survival benefit compared to the other two options. CONCLUSIONS: The combined option of CRT+ICD seems to be better than the option of CRT alone, although no clear improvement in survival was found for the combined option. It would be advisable to perform a direct comparative study of these two options.
ABSTRACT
No disponible
Subject(s)
Humans , Male , Middle Aged , Head and Neck Neoplasms/complications , Syncope/etiology , Head and Neck Neoplasms/pathology , Head and Neck Neoplasms/diagnosis , Disease Progression , Neoplasm Invasiveness , Syncope/pathologyABSTRACT
INTRODUCTION AND OBJECTIVES: To assess the diagnostic capacity of a protocol to study syncope of unknown cause in which electrophysiological studies and tilting table tests are selectively used. PATIENTS AND METHODS: The study was performed in 137 consecutive patients (94 men and 43 women, with a mean age of 57.6+/-18.3 years) with syncope of unknown cause after the initial clinical evaluation, who were divided into two groups. Group A consisted of 77 patients meeting any of the following criteria: a) presence of structural heart disease; b) abnormal ECG; c) presence of significant non-symptomatic arrhythmia in the Holter recording, and d) presence of paroxysmal palpitations. These patients initially underwent an electrophysiological study. Group B consisted of 60 patients not meeting any of the above criteria, who were initially submitted to tilting table tests.Results. In group A, the electrophysiological study was positive in 43 patients (55%). In group B, the tilting test was positive in 41 patients (68%). Among patients in group A with a negative study, 20 (59%) were submitted to the tilting table test, with positive results in 7 cases (35%). Five patients from group B with a negative tilting test underwent the electrophysiological study, which was negative in all of them. Overall, a positive diagnosis was achieved in 91 of 137 patients (66%). CONCLUSIONS: In patients with syncope of a non-apparent cause in the initial assessment, selective use of electrophysiological studies or tilting table tests, guided by clinical criteria, allows for a positive diagnosis in over 60% of the cases. Our results suggest that the tilting table test should be performed in cases of group A with a negative electrophysiological study.
Subject(s)
Syncope/diagnosis , Clinical Protocols , Electrophysiology , Female , Humans , Male , Middle Aged , Retrospective Studies , Syncope/etiology , Syncope/physiopathology , Tilt-Table TestABSTRACT
The knowledge about vasovagal syncope has hugely grown since its initial description by Lewis in 1932. Nevertheless some critical gaps remain, affecting specially to the patient management. There are not enough data about the natural history of the process and, because of that, no useful markers are known to identify patients who need or would benefit from a specific treatment. A diagnostic test with a sensibility/specificity relationship good enough to be a diagnostic gold standard is lacking. Although tilt-table test can be helpful in diagnosis, its sensitivity is, nowadays, unknown. Available data about reproducibility of tilt test are scarce and sometimes contradictory, specially with positive tilt test results. Should the lack of reproducibility of positive results found by some authors be confirmed, the usefulness of serial tilt tests in selecting treatment would be seriously affected. No evidence about the existence of an effective treatment for vasovagal syncope has been published yet, not either about the advantage of an specific strategy in selecting it. Therefore, tilt test has not been proved to be a more useful tool in selecting therapy for patients with vasovagal syncope.
Subject(s)
Syncope, Vasovagal/diagnosis , Tilt-Table Test , Humans , Syncope, Vasovagal/therapyABSTRACT
INTRODUCTION AND OBJECTIVES: Since physiological pacing systems have become available, a debate has raged about the merits of atrial versus ventricular pacing in the sick sinus syndrome. The goal of this retrospective report was to study the long term incidence and the independent predictors for atrial fibrillation and stroke in 153 paced patients with sick sinus syndrome, adjusting for differences in baseline clinical variables with multivariate analysis. METHOD AND RESULTS: From 1980 to 1994, we implanted 32 dualchamber, 33 atrial, and 88 ventricular pacemakers to treat patients with sick sinus syndrome. After a maximum follow-up of 177 months (median 30 months for paroxismal atrial fibrillation, 45 months for chronic atrial fibrillation and 43,5 months for stroke) the actuarial incidence of paroximal atrial fibrillation was 7.8% at 1 year, 29% at 5 years and 42% at 10 years. The actuarial incidence of chronic atrial fibrillation was 1.3% at 1 year, 9.8% at 5 years and 22% at 10 years. Independent predictors for paroxismal AF from Cox's model was history of atrial tachyarrhythmias (p < 0.0001), chronic obstructive pulmonary disease (p = 0,006) and age (> 70 years-old) (p = 0.035). Only a history of atrial tachyarrhythmias before pacemaker implant was an independent predictor for chronic atrial fibrillation (p < 0.0001). The odd ratio for paroxismal atrial fibrillation in patients with previous atrial tachyarrhythmias and chronic atrial fibrillation were 6 (2.8-12) and 4 (1.6-9.7) (95% confiance limits). Actuarial incidence of stroke was 3% at 1 year, 10% at 5 years and 14% at 10 years. Independent predictors for stroke were history of peripheral vascular disease (p = 0.033) and hypertensive cardiomyopathy (p = 0.015). Development of paroxysmal and chronic atrial fibrillation during the follow-up were higher in patients with stroke (p < 0.001 and p < 0.05). CONCLUSIONS: Development of atrial fibrillation and stroke in paced patients with sick sinus syndrome are strongly determined by clinical variables. Preimplant paroxysmal atrial tachyarrhythmias is the most important predictor for atrial fibrillation in the follow-up.
Subject(s)
Atrial Fibrillation/epidemiology , Cerebrovascular Disorders/epidemiology , Pacemaker, Artificial/adverse effects , Sick Sinus Syndrome/therapy , Actuarial Analysis , Aged , Aged, 80 and over , Atrial Fibrillation/etiology , Cerebrovascular Disorders/etiology , Female , Humans , Incidence , Male , Middle Aged , Multivariate Analysis , Retrospective Studies , Sick Sinus Syndrome/complicationsABSTRACT
The analysis of heart rate variability provides valuable information in the noninvasive study of neurovegetative activity and its modifications induced by drugs, physiological maneuvers or disease processes, and in the evaluation of prognosis and risk stratification in different cardiovascular diseases. A review is made of the different methods used to study heart rate variability, and an account is given of the information provided by spectral methods and the new procedures based on the complex demodulation of the time series composed of consecutive cardiac cycles. The limitations of the spectral methods are deal with, particularly in defining the time-dependent changes in variability and their relation to clinical events. Likewise, a description is given of the ability of complex demodulation to define the time course of the oscillations into which the analyzed time series is decomposed. Complex demodulation based on the fast Fourier transform and its inverse is able to establish the instantaneous amplitude and frequency of each of the oscillations contained in the time series, separated by specific filters in the previously selected frequency bands (high: 0.15-0.40 Hz, low: 0.04-0.15 Hz, or very low: < 0.04 Hz), and from which the original signal may be reconstructed. The evaluation of the different methodological approaches, and the analysis of the causal relations between the variability modifications and clinical events will further extend the clinical relevance of the study of heart rate variability.
Subject(s)
Electrocardiography/methods , Heart Rate/physiology , Signal Processing, Computer-Assisted , Humans , Periodicity , Time FactorsABSTRACT
It is not well established the importance of 50 Hz alternating current (AC) (that supplies most of house appliances) as a source of inappropriate inhibition of today cardiac pacemakers (PM). This problem has been studied in 58 consecutive patients permanently paced (VVI unipolar) for AV block with 27 different PM models from 11 manufacturers. Under ECG monitoring, 50 Hz AC was applied through a pair of electrodes set at both patient's wrists using a battery powered external source, with voltage ranging between 0 and 45 V. Inappropriate inhibition was considered if PM pauses longer than twice the programmed escape interval of the PM were observed during interference. This happened in 46 patients (79.3%), with PM from all 11 manufacturers, with voltages ranging from 3 to 28 V. In each case, inhibition was seen with a narrow voltage window between no interference detection and interference reversion of the PM. Only 3 patients (5.2%) referred perception of electrical current during the study. Three of the patients studied had complained, prior to the study, about dizziness or presyncope related to touching electrical devices and in all of them inappropriate inhibition was observed during interference. We conclude that: 1) it is possible to demonstrate inappropriate inhibition caused by 50 Hz AC galvanic interference in a high percentage of unipolar PM; 2) This inhibition occurs at current levels that in most cases are not sensed by the cutaneous nerves, and 3) although the problem seems to have little clinical significance it should be investigated in paced patients with symptoms attributable to inappropriate inhibition of their PM.
Subject(s)
Electricity/adverse effects , Equipment Failure , Pacemaker, Artificial , Aged , Electrocardiography , Female , Humans , Male , Middle AgedABSTRACT
Serial signal-averaged electrocardiograms were recorded every 72 hours in 60 patients admitted to the coronary care unit with acute myocardial infarction. The prevalence of late potentials was 61.6% (37 patients) during hospitalization. Of these 37 patients, late potentials appeared transiently in 20 (54%), while in 9 patients (24%), once late potentials had appeared, they tended to persist. No specific clinical characteristics were related to the development of late potentials (site of infarction, peak creatine kinasa activity, Killip class, thrombolytic therapy). The presence of late potentials did not identify patients who developed clinically significant ventricular tachyarrhythmias (primary ventricular fibrillation, ventricular tachycardia). The abnormal late potentials were modified by the administration of lidocaine. This lack of correlations suggests that the abnormal signal averaged electrocardiogram and complex ventricular arrhythmias during acute myocardial infarction have different electrophysiological bases. Late potentials could be only a bystander electrophysiological phenomenon without clinical correlation in this clinical phase.
Subject(s)
Electrocardiography , Hospitalization , Myocardial Infarction/physiopathology , Aged , Female , Humans , Male , Middle Aged , Myocardial Infarction/epidemiology , Prevalence , Prospective StudiesABSTRACT
Ventricular arrhythmias detected in the late-hospital phase of myocardial infarction have been identified as a risk factor for sudden death, being their prognostic value independent of ventricular function. However, relations between both factors are not clarified. In order to study hypothetic associations between ventricular arrhythmias and some clinical, hemodynamic and angiographic variables, 60 patients (52 males, 8 females) underwent 24-hour Holter recordings and cardiac catheterization with left ventricular and coronary angiographies, 3-5 weeks after hospital admission. Past history data, acute phase complications and hemodynamic and angiographic results were compared between patients with and without significant ventricular arrhythmias during Holter monitoring (10 or more PVC's/hour and/or repetitive forms). No significant differences were found between both groups neither in mean age nor in the incidence of previous angina or infarction, cerebral ischemia, diabetes, lipid disorders or subjective feeling of being under psychological stress. Prior history of arterial hypertension was, however, significantly more frequent in patients with ventricular arrhythmias (53.3% vs 17.8%; p = 0.0183). No differences were observed in the localization of the infarct or in the complications during the acute phase (CPK peak, Killip's score, angina after 24 hours of evolution, intraventricular or A-V conduction disorders and supraventricular and ventricular arrhythmias). Among hemodynamic data, only left ventricular and aortic systolic pressures were different in both groups, being significantly higher in patients with ventricular arrhythmias. There were not differences in left ventricular segmentary contraction and in number of coronary vessels involved. To conclude, significant ventricular arrhythmias were recorded in 25% of patients.(ABSTRACT TRUNCATED AT 250 WORDS)
Subject(s)
Arrhythmias, Cardiac/etiology , Myocardial Infarction/complications , Adult , Arrhythmias, Cardiac/physiopathology , Female , Heart Function Tests , Humans , Male , Middle Aged , Myocardial Infarction/pathology , Prospective Studies , Risk FactorsABSTRACT
The linear correlation of the circadian rhythms (CR) of heart rate (HR) with those of ventricular extrasystole (VE) is analyzed by electrocardiographic ambulatory monitoring in 32 patients: 22 with ischemic post-infarction cardiopathy (group A) and ten free of structural cardiopathy (group B). Variability expressed as the coefficient of ventricular extrasystole variation (100 x standard deviation/mean) presented an inverse correlation with the number of recording extrasystoles. Linear correlation between HR and VE was statistically significant in 72% of recordings in group A, and in 60% in group B. The percentage of cases with significant linear correlation was greater on analyzing the three-minute periods than with the longer periods. When the cases analyzed presented over 200 extrasystoles, the percentage with significant linear correlation between HR and extrasystole was greater in group A than in group B. The circadian rhythm of the ventricular extrasystoles using interpolation of a cosinor function was significant in 50% of group A cases, and in 60% of group B. The achrophases were diurnal in group B, but only in 45% of cases in group A, two correspondence models being found between the CR achrophases and the inverse linear correlation between HR and VE.
Subject(s)
Cardiac Complexes, Premature/physiopathology , Circadian Rhythm , Heart Rate , Myocardial Infarction/complications , Adolescent , Adult , Cardiac Complexes, Premature/etiology , Female , Heart Ventricles , Humans , Male , Middle Aged , Retrospective Studies , Time FactorsABSTRACT
Three hundred hospital patients with syncope (193 males and 107 females, mean age 61 +/- 17 years) were prospectively evaluated with a standard protocol. Associated diseases were found in 76.7% of cases. The incidence of heart diseases was 50.8% in males vs 32.7% in females (p less than 0.003). The cause of syncope was diagnosed in 250 patients (84%). The diagnosis was made at initial evaluation in 101 patients (group A); in the remaining patients (group B), no diagnosis was made in 25% (16.6% of the overall series) despite a wide array of investigations. Syncope due to arrhythmia was diagnosed in 57.6% (group A: 91.1% group B: 40.7; p less than 0.0001); cardiac syncope not due to arrhythmia was diagnosed in 4%, and other types of syncope in 21.6% (group A; 6.9%; group B: 29.1%; p less than 0.0001). It is concluded that a) the hospital population of patients with syncope represents a subgroup of advanced age and a high incidence of associated diseases; b) one third of patients were diagnosed at the initial evaluation, whereas in 25% of the remaining ones no diagnosis was obtained, and c) in these patients, arrhythmia is the most likely cause of syncope.
Subject(s)
Syncope/epidemiology , Adult , Age Factors , Aged , Aged, 80 and over , Arrhythmias, Cardiac/complications , Cardiovascular Diseases/complications , Diabetes Complications , Female , Humans , Inpatients , Male , Middle Aged , Nervous System Diseases/complications , Prospective Studies , Sex Factors , Syncope/etiologyABSTRACT
Two cases of bidirectional tachycardia are presented. The ventricular origin of these arrhythmias was assessed by His bundle recordings. Because of the V1 morphology of the ventricular complexes during tachycardia in one case and the unknown etiology in the other, these arrhythmias were considered to be atypical. The involved mechanisms and the causes inducing these tachycardias are discussed. Whatever the involved mechanism, our cases reaffirm the opinion that the terminology bidirectional tachycardia should be used only to describe an electrocardiographic pattern that may be caused by different electrophysiological mechanisms.
Subject(s)
Electrocardiography , Tachycardia/physiopathology , Adult , Female , Humans , Middle Aged , Tachycardia/etiologyABSTRACT
Seven anaesthesized mongrel dogs subject to thoracotomy were used in a electronic simile of A-V accessory pathway with retrograde conduction to generate reentrant tachycardias with different ventriculo-atrial delays. This was done both under control conditions and following amiodarone i.v. administration. The ability to predict tachycardia cycle length was studied, using a mathematical model of the circuit, in which the cycle length is obtained from the function of nodal conduction and the time of extranodal conduction of the circuit. An analysis was made of the repercussions in using four different mathematical functions describing nodal conduction: three were non-linear (exponential and hyperbolic A and B) and one linear. In the case of the first three, the consequences of using a direct non-linear data-fitting procedure or an indirect procedure by linear transformations of the functions were studied. The exponential and hyperbolic B functions provide a better prediction of tachycardia cycle length on being used in the model; in the case of these functions, a mean value of the squared differences between the real and estimated values of 19.1 +/- 31.0 ms2 and 19.1 +/- 26.7 ms2, respectively, was obtained.
Subject(s)
Models, Cardiovascular , Tachycardia, Atrioventricular Nodal Reentry/physiopathology , Animals , Dogs , Evaluation Studies as Topic , Heart Conduction System/physiopathology , Tachycardia, SupraventricularABSTRACT
Thirty-four anaestheized mongrel dogs subjected to thoracotomy were used to study AV node conduction during atrial pacing at increasing rates. Epicardial atrial electrodes were used, together with endocavitary recordings of His bundle electrogram. An analysis was made of the repercussions involved in using four different mathematical functions describing nodal conduction: three were nonlinear (exponential and hyperbolic A and B) and one linear. In the case of the first three, the consequences of using a direct nonlinear data-fitting procedure or an indirect procedure by linear transformations of the functions were studied. The exponential and hyperbolic B functions provided the least mean squared residual in quantifying nodal conduction (8.6 +/- 10.8 ms2 and 10.8 +/- 13.9 ms2, respectively). The use of nonlinear function transformation into a linear representation caused loss of precision in the fit to the data in the case of the exponential function (18.3 +/- 22.2 ms2 versus 8.6 +/- 10.8 ms2, p less than 0.01) and, to a lesser extent, in the case of the hyperbolic B function (12.5 +/- 16.4 ms2 versus 10.8 +/- 13.9 ms2, P less than 0.05).