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Biomedical subjects

K P Bethge

Publications and source records attributed to K P Bethge.

At least 19 recordsLinked to original sources
PubMed1996

[Transient pacemaker dysfunction and spontaneous arrhythmias in symptomatic and asymptomatic patients with ventricular demand pacemakers].

This prospective cross-sectional study include 100 consecutive patients (56 males, 44 females, 29 to 86 (mean = 67.5 +/- 12.2) years) with ventricular inhibited demand pacemakers 0.1 to 94.7 (mean 23.3 +/- 25.4) months after pacemaker implantation. Fifty-two patients were free of symptoms, whereas 48 patients were still complaining of syncope, dizziness, or palpitations. After history, physical examination, and 12-lead standard ECG all patients underwent 24-h Holter monitoring. A computer-aided analysis of spontaneous arrhythmias was done first. In a second run computed-aided analysis of transient pacemaker dysfunctions was performed with a specially designed pacemaker module. There were no significant differences between asymptomatic and symptomatic patients with regard to the incidence of transient pacemaker dysfunctions, with regard to defined types of pacemaker dysfunctions, spontaneous ventricular arrhythmias, and with regard to supraventricular tachycardias. A significant difference between asymptomatic and symptomatic patients was found, however, regarding the Lown classification of ventricular arrhythmias, because asymptomatic patients showed class 0 and I/II arrhythmias more frequently (p < 0.025). In the 100 patients a total of 6609 pacemaker dysfunctions were observed, 5104 failures to sense and 1505 inappropriate inhibitions. Most patients showed up to 240 pacemaker dysfunctions per 24 h. There were no failures to capture. Different types of pacemaker dysfunctions were found with different clinical implications. Due to the Holter findings in nine patients pacemakers were reprogrammed or replaced. After pacemaker implantation the number of patients with severe symptoms significantly decreased compared to the number of patients before pacemaker implantation. Nonetheless, there was a number of patients still complaining of symptoms after pacemaker implantation. In only a few patients did pacemaker implantation worsen symptoms . Our data show that with use of long-term ECG transient pacemaker dysfunctions and spontaneous arrhythmias are more frequent than patients' history and common standard techniques in the pacemaker clinic may suggest Holter monitoring, therefore, is a useful diagnostic tool, not only in symptomatic, but also in asymptomatic pacemaker patients. It allows to obtain a reliable survey of the real amount of transient pacemaker dysfunctions in the individual patient, which is the base for further therapeutic decisions.

Adult↗
PubMed1994

[The reliability of computer-assisted long-term ECG analysis of pacemaker malfunction in patients with ventricular demand pacemakers].

The importance of the pacemaker follow-up clinic has markedly increased in the face of the currently available multiprogrammable pacemakers. In contrast to the common standard techniques in assessing pacemaker dysfunctions, Holter monitoring allows the detection of transient pace-maker dysfunctions during a long period of time. Especially computer-aided analysis provides a considerable progress, because different pacemaker dysfunctions can be detected during prolonged time periods, and--in contrast to visual analysis--a reliable survey of the real extent of transient pacemaker dysfunctions in the individual patient is assessed. The reliability of computer-aided analysis by a specially designed module was prospectively investigated in 100 consecutive patients with permanent ventricular inhibited demand pacemakers. It could be demonstrated that the positive predictive accuracy of this analysis was limited to 60.2% in detecting failures to sense and 63.2% in detecting inappropriate inhibitions, respectively. All detected failures to capture were false positive events. The positive predictive accuracy, therefore, was not calculated for this category of event. The overall positive predictive accuracy was 59.9%. In contrast, the sensitivity of computer-aided analysis was remarkably high. Possible causes of false positive and false negative findings are described. The reliability of pacemaker pulse detection was also investigated. Out of 100 analyzed Holter recordings five showed a temporary total loss of pacemaker pulses. Loss of single pacemaker pulses was found in 30 patients. False positive pacemaker pulses were seen in three patients. These results show that visual control and validation by an experienced physician are mandatory.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Sudden cardiac death while wearing a Holter monitor.

The Holter tapes of 61 patients (46 men, mean age +/- standard deviation 65 +/- 11 years) with sudden cardiac death while being monitored were analyzed. Thirty-eight patients were known to have coronary artery disease, 5 had cardiomyopathy, and 7 had aortic valve disease. Etiology remained unknown in 11 patients. Mean New York Heart Association functional class was 2.5 +/- 0.7. Thirty patients had received antiarrhythmic drugs and 32 had received digitalis. Sudden death occurred at rest in 73%. In the hours before death, repetitive ventricular arrhythmias were found in 50 patients (82%), with atrial fibrillation in 34%. Patients with bradyarrhythmic death (18%) had less complex ventricular activity compared to patients with tachyarrhythmic death (p less than 0.01). Lethal arrhythmias--monomorphic ventricular tachycardia, polymorphic ventricular tachycardia, torsades de pointes, primary ventricular fibrillation, and 1:1 conducting atrial tachycardia--were found in 26 (43%), 15 (25%), 5 (8%), 3 (5%), and 1 patient, respectively. The coupling interval of the final ventricular tachycardia correlated inversely with the initial frequency of ventricular tachycardia (p less than 0.05). For patients with tachyarrhythmic death, an increase of heart rate within the last 3 hours was noted (83 vs 89 beats/min, p less than 0.05). Ventricular premature complexes and the proportion of patients with greater than 2 couplets and greater than 2 triplets increased significantly only within the last hour before death.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

Radiofrequency catheter ablation in recurrent ventricular tachycardia.

Catheter ablation by radiofrequency energy was carried out in 10 patients with one type of recurrent monomorphic sustained ventricular tachycardia resistant to medical antiarrhythmic management. Electrophysiological studies before ablation included activation and pace-mapping. In all patients, the origin of the tachycardia was localized in the left ventricle: in the septum in six, at the posterolateral wall in three and anterobasal in one. The earliest onset of endocardial activation preceding the QRS complex during ventricular tachycardia ranged between -45 and -90 ms. Transcatheter ablation was performed with a bipolar or quadripolar catheter using a radiofrequency generator (HAT 100, Osypka). No complications occurred during the ablation procedure. Thereafter, in all patients, the clinical tachycardia was no longer inducible by programmed stimulation. During a follow-up period of 22 to 32 months including eight patients, the tachycardia recurred in two; one of these patients subsequently died suddenly. A third patient had one episode of a new type of sustained ventricular tachycardia some hours after catheter ablation. In the remaining patients, there was no recurrence of symptomatic tachycardia under maintenance of the antiarrhythmic management which, prior to ablation had been ineffective. Thus, our preliminary results suggest that radiofrequency catheter ablation might be beneficial for these high risk patients.

Cardiac Pacing, Artificial↗
PubMed1991

[Prevalence of late potentials in high frequency signal-averaged electrocardiography and arrhythmias in long-term ECG in healthy probands].

In a prospective study 79 symptom-free persons (41 females; 38 males) with an age range of 22-69 (mean 44) years were investigated by 48-h continuous ambulatory electrocardiography and by the signal-averaging ECG according to Simson's technique after having normal findings with echocardiography, standard ECG at rest and exercise stress test. Late potentials were defined according to Denes criteria (40 Hz highpass-filter); at least two out of the following three criteria had to be fulfilled for a correct positive finding: 1) QRS duration (QRSdur) greater than 120 ms; 2) root mean square of the last 40 ms (RMS 40) less than 20 microV; 3) mean duration of terminal low-amplitude signals (LAdur) greater than 39 ms. With long-term ECG 25% of the test subjects had no ventricular extrasystoles (VES), 28% had uniform VES, 33% multiform VES, 10% couplets, and 4% short runs of ventricular tachycardia during 48-hour recordings. Only 19% of them showed more than 48 VES/48 h. Individuals of advanced age demonstrated arrhythmias of higher Lown classes, as well as more frequent VES. By applying the signal-averaging technique 12.6% of the apparently healthy individuals showed late potentials, but none had LAdur greater than 45 ms. Individuals of higher age had not more late potentials than the younger ones. However, individuals with incomplete right bundle branch block pattern (n = 6) demonstrated with 50% significantly more often later potentials in comparison to 9.6% of those without this pattern (n = 73) (P less than 0.05). There was no correlation between late potentials and spontaneous arrhythmias, neither with regard to Lown classes, nor with regard to the frequency of VES. In conclusion, late potentials may occur in some individuals without apparent cardiovascular disease; they are unrelated to age as well as to spontaneous ventricular arrhythmias in normals.

Adult↗
PubMed1991

Classification of arrhythmias.

In view of the broad spectrum of arrhythmias and their considerable spontaneous variability, there is a need for a classification of arrhythmias as a basis for scientific and clinical decision making. From the clinical point of view, a classification should consider (a) hemodynamic consequences, (b) prognostic significance of arrhythmias, and (c) should allow assessment of efficacy of antiarrhythmic treatment. Hemodynamic consequences of tachycardias are related to the degree of heart rate: The shorter the RR interval the shorter the diastolic filling period, resulting in a decrease of the stroke volume and--above a critical heart rate--in a decrease of the cardiac output. The critical heart rate, on the other hand, is essentially related to the functional status of the heart: The more pronounced the cardiac impairment, the lower the critical heart rate. A second factor favoring hemodynamic impairment due to arrhythmias is the loss of the sequence of atrioventricular contractions. Despite the clinical relevance of hemodynamic consequences of arrhythmias, there is no accepted classification taking these aspects into account. In the past, more interest was directed toward the prognostic significance of arrhythmias. In 1971, Lown and Wolf published a classification of ventricular arrhythmias, assigning risk to advanced grades. This proposal, as those from others, took into account arrhythmias of ventricular origin only. The major concern about the Lown classification, however, relates to the consequences of maximal grading: a patient is assigned to a grade depending on the highest ranking. Thus, a person can only be in one grade, leaving all other arrhythmias grouped below as well as the true frequency of ventricular arrhythmia obscure.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Importance of quantitative analysis of ventricular arrhythmias for predicting the prognosis in low-risk postmyocardial infarction patients. European Infarction Study Group.

In 378 placebo patients enrolled in the European Infarction Study (EIS), a secondary prevention study after acute myocardial infarction, 24-h baseline Holter monitoring was done 14 to 31 days after MI, and the relationship of electrical (ventricular arrhythmias) and mechanical (clinical signs of ventricular dysfunction) risk factors was analysed on the basis of mortality during the subsequent 2 years of follow-up. There was a rather low overall 2-year mortality rate of 6.9%. Consecutive arrhythmias (ventricular pairs and runs of ventricular premature beats) and left-ventricular dysfunction alone were associated with a low mortality of 4.0% and 3.6%, respectively. However, the combination of both defined a high-risk group characterized by a 2-year mortality rate of 16.7%. Additionally, the risk of dying was dependent on the frequency of consecutive arrhythmias: 22.2% of the patients with greater than 10 ventricular pairs per day died during the follow-up period in contrast to 9.9% of those with only 1-10 ventricular pairs per day. Thus, only the combination of electrical and mechanical risk factors, and especially the frequency of consecutive VPB, is helpful in identifying a subgroup of postMI patients with poor clinical outcome. An intervention study should restrict itself to this risk population only.

Arrhythmias, Cardiac↗
PubMed1990

[Cardiac arrhythmia in patients with chronic obstructive lung disease and therapy].

In 38 patients with chronic obstructive lung disease (COLD), lung function tests, blood gas analysis, catheterisation examination of the right heart, and long-term (Holter) ECG were performed. In comparison with normal subjects, all the patients had a higher mean 24-hour heart rate of 97 +/- 11/minute, and a disturbance of the physiological day/night rhythmicity. Seventeen patients (group I) revealed no major arrhythmias (Lown I to III). More than 50 per cent of the patients (group II) were found to have complex arrhythmias (Lown IV), together with an elevated incidence of polymorphic ventricular and superventricular extrasystoles. A significant correlation of the arrhythmias with the severity of the obstruction or pulmonary hypertension was not observed. Only the long-term follow-up of these patients will provide us with information about the prognostic significance of the complex arrhythmias and about indications for anti-arrhythmic treatment.

Bronchodilator Agents↗
PubMed1988

[Value of various concepts in long-term electrocardiography].

With the introduction of long-term ECG by N. Holter more than 25 years ago a more sensitive detection of spontaneous arrhythmias and ST-changes became possible compared with the standard ECG at rest. Unfortunately, visual high-speed analysis of the tapes caused remarkable loss of stored informations due to the failure of rapid identification. Full disclosure of the ECG, therefore, is a valuable supplement to long-term ECG. As an isolated method, however, it cannot be recommended since the significantly reduced amplitude and paper speed of full disclosure likewise is responsible for a remarkable loss of informations. Only computer-aided analysis of the ECG provides more complete information and at the same time more quantitative data. Analysis of the accuracy of different computer-based systems showed, however, that a sensitivity as well as a positive predictive accuracy of 100% remains the exception to the rule. Moreover, the spectrum of cardiac arrhythmias and ST-changes identifiable by automatic analysis is small. For these reasons, interaction of the user is mandatory--in order to validate computer results as well as to detect ECG abnormalities unidentifiable by computer. The first is possible only to a limited degree with discontinuous ECG recording by event recorders, the last remains impossible. Thus, the promising concept of real-time cardiac monitors should be considered investigational or experimental at this time.

Arrhythmias, Cardiac↗
PubMed1988

[Monitoring of pacemaker patients by long-term ECG].

Long-term-ECG is an essential method for detecting transitory pacemaker-dysfunctions. Control of antitachycardia-pacemakers is possible as well as VVI-pacemakers and with restrictions DVI-, VDD- and DDD-pacers. Special pacemaker-control-modules increase the sensitivity for the recognition of dysfunctions. Regular check-ups are an important part of guiding the pacemaker-patient.

Arrhythmias, Cardiac↗
PubMed1988

Endocardial late potentials recorded during sinus rhythm in man: incidence in different cardiac disease states.

In a prospective study, 100 patients with various cardiac diseases not selected on the basis of previous ventricular arrhythmias underwent left ventricular endocardial mapping. With 10 different positions of the quadripolar catheter per patient, 90 of the 100 patients showed late potentials. These findings were documented in 50 of 52 patients with coronary heart disease compared to 26 of 34 patients with dilative cardiomyopathy (p less than 0.025). Late potentials in diastole were the most frequent type of abnormal electrogram, found in 82 patients. Fractionated electrograms were documented in 43 patients. They were seen in 27 (52%) coronary patients more often than in 8 (24%) patients with dilative cardiomyopathy (p less than 0.025). Onset of fractionated electrograms in coronary patients was somewhat later (301 +/- 177 ms after the QRS) than in the cardiomyopathy group (263 +/- 141 ms). The duration was longer (189 +/- 114 ms) in the former group than in the latter (148 +/- 87 ms). Thus, endocardial late potentials are not uncommon in patients with various cardiac diseases. The more frequent occurrence in coronary heart disease and the higher frequency of fractionated electrograms may indicate a more inhomogeneous, patchy type of fibrosis in the ischemically diseased myocardium.

Adult↗
PubMed1988

Occurrence and clinical significance of endocardial late potentials and fractionations in idiopathic dilated cardiomyopathy.

In order to assess the occurrence and clinical significance of abnormal electrograms in idiopathic dilated cardiomyopathy, endocardial electrode mapping during sinus rhythm and programmed ventricular stimulation were performed in 52 patients with or without clinical ventricular tachycardia. Abnormal endocardial electrograms were recorded in 77% of the patients and were diffusely distributed over the entire left ventricular endocardium. No relation could be established between the occurrence of late potentials or fractionations and clinical or induced arrhythmias. Endomyocardial biopsy samples were taken from 20 patients and showed that reduced myofibril volume fraction was related to the occurrence of abnormal endocardial electrograms. Neither induced arrhythmias nor the presence of late potentials or fractionations identified patients who died of sudden cardiac death during the mean (SD) follow up of 33 (11) months. Thus abnormal endocardial electrograms recorded during sinus rhythm in idiopathic dilated cardiomyopathy may only be interpreted as being a sign of damage to the myocardial cells.

Action Potentials↗