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Biomedical subjects

L Reinhardt

Publications and source records attributed to L Reinhardt.

At least 19 recordsLinked to original sources
PubMed2001

Prolonged QRS duration increases QT dispersion but does not relate to arrhythmias in survivors of acute myocardial infarction.

QT dispersion has been suggested and disputed as a risk marker for ventricular arrhythmias after myocardial infarction. Delayed ventricular activation after myocardial infarction may affect arrhythmic risk and QT intervals. This study determined if delayed activation as assessed by (1) QRS duration in the 12-lead ECG and by (2) late potentials in the signal-averaged ECG affects QT dispersion and its ability to assess arrhythmic risk after myocardial infarction. QT duration, JT duration, QT dispersion, and JT dispersion were compared to QRS duration in the 12-lead ECG and to late potentials in the signal-averaged ECG recorded in 724 patients 2-3 weeks after myocardial infarction. Prolonged QRS duration (> 110 ms) and high QRS dispersion increased QT and JT dispersion by 12%-15% (P < 0.05). Presence of late potentials, in contrast, did not change QT dispersion. Only the presence of late potentials (n = 113) was related to arrhythmic events during 6-month follow-up. QT dispersion, JT dispersion, QRS duration, and QRS dispersion were equal in patients with (n = 29) and without arrhythmic events (QT disp 80 +/- 7 vs 78 +/- 1 ms, JT disp 80 +/- 6 vs 79 +/- 2 ms, mean +/- SEM, P > 0.2). In conclusion, prolonged QRS duration increases QT dispersion irrespective of arrhythmic events in survivors of myocardial infarction. Presence of late potentials, in contrast, relates to arrhythmic events but does not affect QT dispersion. Therefore, QT dispersion may not be an adequate parameter to assess arrhythmic risk in survivors of myocardial infarction.

Aged↗
PubMed1997

Patients with valvular heart disease presenting with sustained ventricular tachyarrhythmias or syncope: results of programmed ventricular stimulation and long-term follow-up.

BACKGROUND: Programmed ventricular stimulation is commonly used to guide therapy in post-myocardial infarction patients with sustained monomorphic ventricular tachycardia (VT) or ventricular fibrillation (VF). In patients with valvular heart disease presenting with spontaneous VT, VF, or syncope, the usefulness of this technique is still unclear. The aim of the study was to analyze whether programmed ventricular stimulation was helpful in guiding therapy and determining prognosis in 97 patients with valvular heart disease presenting with VT (60%), VF (18%), or syncope (22%). METHODS AND RESULTS: Patients were classified as having either predominant ventricular pressure or volume overload or no significant pressure or volume overload. Overall, sustained VT or VF was inducible in 38 (39%) and 19 (20%) patients, respectively. Forty-six (47%) patients were discharged on antiarrhythmic drugs, 29 (30%) received an implantable cardioverter-defibrillator, and 22 (23%) remained without therapy. With serial drug testing, inducibility was completely or partially suppressed in 18 (19%) and 9 (9%) patients, respectively. During a mean follow-up of 51 months (n=97), 17 patients (18%) died (sudden death, n=7; heart failure, n=4; noncardiac causes, n=6). One-, 2- and 3-year event-free survival for sudden death, sustained VT, or VF was 77%, 68%, and 61%, respectively. Only inducibility of VT during baseline study (P<.0003) and left ventricular volume overload (P<.008) were significant predictors of arrhythmic events. Recurrence of arrhythmic events occurred in 56% and 56% of patients with complete or partial suppression of inducibility during serial drug testing as well as in 10 of 19 (53%) patients without a change in inducibility. CONCLUSIONS: Although programmed ventricular stimulation seems to predict adverse outcome, serial drug testing is unreliable in guiding therapy. The type of workload imposed on the ventricles influences outcome, being worse in patients with left ventricular volume overload. Therefore, implantation of a cardioverter-defibrillator should be considered early for the management of these patients.

Adolescent↗
PubMed1996

Noninvasive risk modeling after myocardial infarction.

The aim of this study was to extract and combine non-invasive risk parameters from the signal-averaged electrocardiogram (SAECG) and heart rate variability (HRV) based on 24-hour ambulatory electrocardiography to optimize the prognostic value for arrhythmic events after acute myocardial infarction. A prospective series of 553 men < 66 years of age enrolled in the Post-Infarction Late Potential study were analyzed. Within 2 to 4 weeks after acute myocardial infarction, all patients underwent SAECG and 24-hour ambulatory electrocardiography before hospital discharge. During 6 months of followup, 25 patients (4.5%) experienced arrhythmic events (sustained ventricular tachycardia, n = 11; ventricular fibrillation, n = 7; sudden cardiac death, n = 7). The predictive power of SAECG and HRV parameters was assessed using a Cox proportional-hazards model. In HRV analysis, the most significant differences between patients with and without arrhythmic events were observed for the beat-to-beat parameter root-meansquare of successive RR differences [RMSSD]): 25.7 +/- 16.9 ms in patients with arrhythmic events versus 34.1 +/- 18.6 ms in patients free of arrhythmic events (p = 0.004). Time domain analysis of the SAECG showed the QRS duration to be most significantly different in both patient groups: 106.4 +/- 18.7 ms (arrhythmic events) versus 95.3 +/- 18.7 ms (no arrhythmic events) (p = 0.001). Based on the Cox regression model, RMSSD and QRS duration were demonstrated to be independent significant risk factors (regression coefficient for QRS duration: cq = 0.014 +/- 0.006 ms(-1), p = 0.014; for RMSSD: cr = -0.041 +/- 0.016 ms(-1), p = 0.009). Based on the regression coefficients, an analytic risk model was developed describing the arrhythmic risk as a function of QRS duration, RMSSD, and time after infarction. We conclude that the combination of beat-to-beat changes of heart rate measured by RMSSD and QRS duration from the SAECG enhances noninvasive risk stratification after myocardial infarction.

Arrhythmias, Cardiac↗
PubMed1996

Predictive value of wavelet correlation functions of signal-averaged electrocardiogram in patients after anterior versus inferior myocardial infarction.

OBJECTIVES: This study sought to evaluate the prognostic value of wavelet correlation functions of the signal-averaged electrocardiogram (ECG) for arrhythmic events in patients after myocardial infarction. BACKGROUND: Wavelet transform of the signal-averaged ECG has been shown to be a nonstationary analysis technique describing the time evolution of frequency spectra throughout the QRS complex. To quantify the wavelet transform, we introduced the new concept of the wavelet correlation function. METHODS: The relation among wavelet correlation functions, ventricular late potentials and the site of infarction was investigated in 769 men < 66 years old who survived the acute phase of myocardial infarction (351 [46%] anterior, 418 [54%] inferior infarctions). Signal-averaged ECG recordings were obtained 2 to 3 weeks after infarction. During 6 months of follow-up, 33 patients (4.3%) experienced a malignant arrhythmic event. Wavelet correlation functions of the signal-averaged ECG were evaluated in a time-frequency plane ranging from 25 ms before QRS onset to 25 ms after QRS offset in the frequency range between 40 and 100 Hz. RESULTS: Patients with an anterior infarction had lower mean wavelet correlation coefficients (p < 0.001) and a lower incidence of ventricular late potentials than patients with an inferior infarction (32.3% vs. 42.7%, p = 0.003). The combination of wavelet correlation functions and late potentials increased the total predictive accuracy from 52% to 72% for inferior and from 64% to 76% for anterior infarctions. CONCLUSIONS: Spectral changes in the signal-averaged QRS complex are more prominent in anterior than inferior infarctions. Combination of late potential analysis and wavelet correlation functions increases the prognostic value for serious arrhythmic events after myocardial infarction.

Adult↗
PubMed1996

Multiresolution decomposition of the signal-averaged ECG using the mallat approach for prediction of arrhythmic events after myocardial infarction.

The aim of this study was to analyze the ability of the multiresolution decomposition of the signal-averaged electrocardiogram (ECG) to discriminate between patients who develop life-threatening ventricular arrhythmias after myocardial infarction and those who do not and to compare the predictive values of this approach with those obtained from the analysis of ventricular late potentials in the time domain. Signal-averaged ECGs of 769 prospectively included patients were analyzed. A total of 42 arrhythmic events occurred during the follow-up period. For numerical calculations of wavelet analysis, the total and relative energies of the QRS complex were obtained in seven frequency bands. The combination of the relative energy in the frequency bands 7.8-15.6 Hz and 62.5-125 Hz enhanced statistical performance as compared with the time-domain parameters (positive predictive accuracy, 11.3 vs 8.2%). Combining wavelet transform and time-domain parameters enhanced the predictive values even more (positive predictive accuracy, 14.3%) compared with applying each method alone.

Adult↗
PubMed1996

Heart rate variability in time domain after acute myocardial infarction.

These results suggest that analysis of heart rate variability recorded even very early after acute myocardial infarction (1 to 2 days after onset of pain) is feasible in clinical routine and strongly related to subsequent arrhythmic events and cardiac mortality. Decreased HRV is considered not only a marker of impaired vagal activity of the heart but complete autonomic impairment, strongly associated with the degree of myocardial damage. HRV represents the integrated response of the cardiovascular system to a variety of different influences: the plasma level of catecholamines, the baroreflex activation and the direct sympathetic and vagal activity. The HRV profile is dynamic-HRV reduction caused by myocardial damage changes over time presenting a progressive increase up to normality over a 2-month follow-up. The observed early differences between anterior and inferior myocardial infarction disappear later in the healing phase. However, group analysis results of different HRV indices are stabile over time and highly reproducible, but presenting large individual variations. HRV parameters which are adjusted to heart rate (e. g. CV) seemed to be more stabile. The role of HRV analysis in risk stratification of patients after myocardial infarction is strongly related to the actual model of the genesis of ventricular arrhythmias. Multiple experimental and clinical studies described the development of life threatening ventricular arrhythmias as a multifactorial event which can not be described adequately using just one risk parameter for stratification. The arrhythmogenic substrate representing the underlying inhomogeneity of electrical behaviour of adjacent myocardial areas might be detectable by the analysis of ventricular late potentials or frequency disturbances from the signal averaged ECG. The autonomic modulation of this substrate is represented by an altered heart rate variability. Possible trigger factors to initiate arrhythmias in a modulated arrhythmogenic substrate like ventricular premature beats or transient myocardial ischemia can be detected by conventional arrhythmia and ST segment analysis from Holter tapes. The optimized combination of these non-invasive risk predictors together with well known evident clinical risk parameters, like left ventricular ejection fraction, may lead to a valid set of screening parameters for individual risk estimation after myocardial infarction.

Autonomic Nervous System↗
PubMed1995

Are there gender differences in patients with coronary artery disease presenting with spontaneous sustained ventricular tachycardia and ventricular fibrillation?

The incidence of coronary artery disease (CAD) is greater in men than in women. The aim of the study was to analyze whether any gender-related differences in patients with CAD and documented spontaneous sustained ventricular tachyarrhythmias exist, and which parameters influence the induction of sustained ventricular tachyarrhythmias. The data of 250 patients [43 women (17.2%) and 207 men (82.8%)] with spontaneous sustained ventricular tachycardia [n = 190 (76%)] and fibrillation [n = 60 (24%)] who underwent coronary and left ventricular angiography, electrophysiological study, and signal-averaging electrocardiogram (ECG) form the basis of this analysis. No gender-related differences could be observed in age, number of diseased coronary arteries, history, location and number of myocardial infarctions, presence of left ventricular aneurysm, ejection fraction, type of spontaneous or induced arrhythmias, right ventricular effective refractory period, and signal-averaged ECG parameters. Age, presence of previous myocardial infarction, and ejection fraction were significant predictors (p < 0.001) of inducibility of sustained ventricular tachyarrhythmias. Once CAD has begun, female and male patients present similar clinical and electrophysiologic characteristics. Thus, both genders should benefit similarly from diagnostic and therapeutic approaches if they are referred to the hospital or to invasive interventions at similar intervals in the course of their illness.

Age Factors↗
PubMed1995

An anatomically and electrogram-guided stepwise approach for effective and safe catheter ablation of the fast pathway for elimination of atrioventricular node reentrant tachycardia.

OBJECTIVES: We describe a new stepwise anatomically and electrogram-guided strategy for radiofrequency catheter ablation of the fast pathway. BACKGROUND: Anatomically and electrogram-guided approaches have been developed for slow pathway ablation in patients with atrioventricular (AV) node reentrant tachycardia; however, no stepwise systematic approaches exist for fast pathway ablation. METHODS: Fifty-three patients (mean [+/- SD] age 43 +/- 11 years) with AV node reentrant tachycardia underwent attempted ablation of the fast pathway. The ablation catheter was initially positioned posterior and slightly superior to the site of the maximal His bundle recording region. At these sites, the amplitude of the local atrial potential was usually at least twice as high as the local ventricular potential, and a small proximal His bundle potential was recorded. When the first pulse was ineffective, the ablation catheter was repositioned stepwise slightly inferior to more midseptal sites. RESULTS: After a mean of 3.4 +/- 3.1 radiofrequency pulses (median 2, range 1 to 12), AV node reentrant tachycardia was noninducible in 51 patients (96%). No inadvertent complete AV block occurred. The AH interval was prolonged from 79 +/- 19 to 145 +/- 37 ms (p < 0.001). Thirty-eight patients (72%) developed complete ventriculoatrial block. Recording of a His bundle potential at the target site, stability of the local electrograms and occurrence of fast junctional rhythms during energy applications were more often observed at successful sites than transiently effective or noneffective sites. During a follow-up period of 12 +/- 7 months, 3 (6%) of 51 patients had a clinical recurrence of AV node reentrant tachycardia. CONCLUSIONS: Radiofrequency catheter ablation of the fast pathway using a combined anatomically and electrogram-guided stepwise approach is highly effective and safe. The safety of this approach seems to be due to the stable position of the ablation catheter at the interatrial septum, rather than across the tricuspid annulus, and the larger distance to the central body of the AV node and bundle of His.

Adult↗
PubMed1995

Prognosis and risk stratification after myocardial infarction.

In order to assess prognosis after myocardial infarction, various methods have been used: estimation of ejection fraction, Holter monitoring, detection of ventricular late potentials using signal-averaging techniques, programmed ventricular stimulation of the heart to test the inducibility of ventricular tachyarrhythmias, and parameters that assess heart rate variability. Left ventricular dysfunction is the major determinant for prognosis after myocardial infarction, but left ventricular end-systolic volume may be better than overall ejection fraction. The presence of an 'arrhythmogenic substrate' may be detected by recording low-amplitude, fractionated activity or by artificially introducing premature ventricular extrasystoles using programmed ventricular stimulation. The signal-averaged ECG represents an independent tool for risk assessment. In some studies, signal-averaging and programmed ventricular stimulation proved to be more sensitive for the prediction of sustained ventricular tachycardia than for sudden death. The risk of an arrhythmic event in patients with an abnormal signal-averaged ECG or an abnormal result of programmed ventricular stimulation is increased, although the majority of these patients still do not experience a fatal or life-threatening arrhythmia. This high number of false-positive results limits the practical applicability of the signal-averaged ECG but also of other techniques such as long-term ECG recording. Recent interest has focussed on heart rate variability, which is considered an index of sympatho-vagal interaction after acute myocardial infarction. Patients with decreased heart rate variability have a poorer prognosis than those with normal parameters. Patency of the infarct-related artery is a major factor that governs the potentially beneficial effects of thrombolytic therapy. Many, but not all, studies have shown a reduced prevalence of late potentials after successful thrombolysis or in the presence of an open infarct-related artery. Effective thrombolytic therapy may prevent the development of an abnormal electrophysiological milieu after myocardial infarction. Finally, neurological factors such as depression have been shown to be independent risk factors for mortality after acute myocardial infarction. The role of psycho-social factors and their mechanisms of action need further attention since they open the door for behavioural modification. In conclusion, there are several promising new techniques for identification of patients at risk of ventricular tachyarrhythmias. These techniques seem to be superior to more conventional methods such as long-term ECG monitoring as well as exercise testing. Methods which determine the arrhythmogenic substrate might be combined with a parameter of left ventricular ejection fraction because of the paramount importance of left ventricular pump function. However, due to the large proportion of false-positive results obtained with any of these methods, it seems unlikely that they will clearly surpass the others and be sufficiently accurate for risk assessment in the individual patient.

Electrocardiography↗
PubMed1995

Comparison and combination of late potentials and spectral turbulence analysis to predict arrhythmic events after myocardial infarction in the Post-Infarction Late Potential (PILP) Study.

Ventricular late potentials detected at the end of the QRS complex by the signal-averaged ECG have been shown to predict arrhythmic events after acute myocardial infarction. Spectral turbulence analysis is a novel technique for detecting abnormalities of cardiac electric activation inside the QRS complex. The purpose of this study was to combine these two analysis methods in order to increase the predictive power of the signal-averaged ECG in post-infarction patients. The study comprised a prospective series of 778 males under 66 years of age who survived the acute phase of myocardial infarction. Signal-averaged ECG recordings were performed before hospital discharge 2 to 3 weeks after infarction. The original Simson method was used for recording and analysing the time-domain signal-averaged ECG. Spectral turbulence analysis was performed using the same averaged vector magnitude QRS complexes (Del Mar Avionics). During the follow-up period of 6 months, 33 patients (4.2%) had an arrhythmic event (sustained monomorphic ventricular tachycardia in 13 cases, ventricular fibrillation in eight cases and sudden cardiac death in 12 cases). The predictive power of late potentials in the time domain, spectral turbulence analysis and their combinations were tested together with clinical variables using the Cox regression method.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Comparison of the results of programmed ventricular stimulation from the right ventricular apex and outflow tract: a randomized, prospective study.

OBJECTIVE: The aim of this prospective study was to analyse the yield of programmed ventricular stimulation at the right ventricular apex compared with the outflow tract. METHODS: A stepwise randomized cross-over protocol of programmed ventricular stimulation with alternating stimulation at both sites was used in 66 patients who were studied because of sustained ventricular tachycardia (n = 30), ventricular fibrillation (n = 7), or non-sustained ventricular tachycardia and/or syncope (n = 29). RESULTS: There were no significant differences between the results of stimulation from either right ventricular site with regard to the presence or absence of structural heart disease, spontaneous arrhythmia, ejection fraction or effective refractory periods. Overall, monomorphic ventricular tachycardia was inducible in 33 patients (50%); in 25 patients (75.8%), this arrhythmia was induced from both sites. However, in only 17 of these 25 patients (68%) did the induced monomorphic ventricular tachycardias have the same morphologies and similar (+/- 50 ms) cycle lengths. Ventricular fibrillation was inducible in 11 patients (17%), mostly by three extrastimuli (n = 8; 73%). CONCLUSIONS: (1) stimulation from at least two right ventricular sites is desirable because of their independent contribution to the induction of ventricular tachyarrhythmias, (2) the non-inducibility or inducibility at one ventricular site does not predict the effect at another stimulation site, (3) the effective refractory period at the right ventricular apex and outflow tract do not differ, (4) the inducibility of multiple ventricular tachycardia morphologies emphasizes the importance of documenting the cause of spontaneous arrhythmias with multiple electrocardiographic leads to ensure the correct interpretation of arrhythmias induced by programmed stimulation, (5) clinical or haemodynamic features cannot predict whether one or more stimulation sites will be required for induction of ventricular tachycardia. These results are important for the diagnostic evaluation and assessment of pharmacological or non-pharmacological interventions.

Adolescent↗
PubMed1993

The signal-averaged ECG: time-domain analysis.

During the past decade, the high-resolution electrocardiogram as a non-invasive technique for the detection of ventricular late potentials has developed from an experimental method into a routinely applied non-invasive method for risk stratification of patients after myocardial infarction. Meanwhile, several approaches have been developed for the detection of ventricular late potentials including time-domain analysis, frequency-domain analysis and spectrotemporal mapping. Clinical applications are no longer limited to patients after myocardial infarction, but cover a wider spectrum of different cardiac diseases. This review focuses on some methodological aspects as well as on the results and current clinical applications of the analysis of the signal-averaged ECG in the time domain.

Action Potentials↗
PubMed1992

Evaluation of wellness in an eating disorders program.

The evaluation of treatment effectiveness in an educational or mental health program remains an elusive and too often ignored program component. Therefore, our team of practitioners and educators in an HMO eating disorders program has developed a practical and visual evaluation method which we call the "Circle of Wellness." We define wellness in terms of physical and mental health. Wellness, in this context, is a reduction of eating disorder symptoms and improvement of quality of life and the client. The "Circle of Wellness" is not intended as a test but as a visual representation of a client's progress (pre- and post-program) for client and clinician to discuss. The tool helps identify areas to emphasize in future planning.

Attitude to Health↗
PubMed1992

[Ventricular late potentials--methods and clinical importance].

Ventricular late potentials are due to regionally depressed inhomogenous conduction, mainly in the border zone of a previous myocardial infarction. They can be recorded noninvasively using high-resolution signal-averaging techniques. They are almost never detectable in normals, whereas they represent a frequent finding in postmyocardial infarction patients. The presence of ventricular late potentials after previous myocardial infarction predicts the subsequent occurrence of hemodynamically severe sustained ventricular tachycardia and/or sudden cardiac death. Their predictive significance can be increased by combining signal-averaging with long-term ECG recording and estimates of left-ventricular ejection fraction. However, despite recent major improvements in identification of patients at risk, there is still a need for an effective mode of prevention of serious ventricular tachyarrhythmias after myocardial infarction.

Death, Sudden↗
PubMed1983

Vascular abnormalities in lichen aureus.

Lichen aureus is an infrequently reported subset of the pigmented purpuric dermatoses. A review of the English literature suggests the golden to purple colored lesions are asymptomatic or mildly pruritic with no regression once established. A case report of a 56-year-old man with lichen aureus of the thighs is presented. This case is unusual in that the patient had persistent pain at the lesion site. Furthermore, increased capillary fragility and koebnerization were both demonstrated. Treatment of an asymptomatic urinary tract infection resulted in temporary subjective and objective improvement.

Capillary Fragility↗