In our study, 12 patients with ventricular arrhythmias, but without any documented cardiac disease, and 10 healthy volunteers were investigated by spin echo magnetic resonance tomography (MRT) using a 0.5 Tesla magnet. Axial T1-weighted spin-echo sequences, as well as double angulated, multislice-multiphase sequences were acquired. Left- and right-ventricular volumes were then evaluated by outlining the endocardium in an end-systolic and an end-diastolic frame. The right-ventricular free wall and the right-ventricular outflow tract were investigated for myocardial thickness and intramural fat.

Various symptoms can be correlated with ECG alterations (arrhythmias as well as ischemia). A simultaneous ECG registration during a symptomatic period excludes or confirms ECG alterations as cause of the symptoms. Otherwise symptoms can be probably related to arrhythmias or ischemia, if asymptomatic precursors of a specific symptom, e.g. syncope can be found in the ECG record. The continuous recording of an ECG over a long period (24 hr and more) enhances the chance to correlate symptoms with the ECG. Prior to Holter monitoring (HM) 63% of the patients (total 2420 HM) had a history of one (59%) or more (41%) symptoms. During one 24 hr HM only 20% developed a typical symptomatic period, 85% patients with a symptomatic history. In 60% (290/480 HM) arrhythmias could be excluded as underlying cause of the symptoms. Palpitations prior to HM were reported in 17-31% of the patients. During HM about 56% of the symptomatic patients complained of palpitations, whereas in 37-47% arrhythmias could be related to the symptom. Dizzy spells, presyncopes and syncopes were reported prior to HM in 25-53%, during HM in 56-65% of the symptomatic patients, whereas in 37-47% a morphologic substrate could be found in the Holter-ECG. Therefore in patients with SY precursing arrhythmias should be taken into account, which could be detected in 36-46%. Otherwise 40-54% of patients with SY had completely uneventful HM. Angina prior to HM occurred in 13% among our patients. During HM 20% developed typical symptoms and ST-depression, whereas 67-80% of ST-alterations were ‘silent’.

The variability of variables influences conclusions in the measurement of biologic variables particularly if the variability of methodological variables are unidentified or of unknown range. Therefore prior the interpretation of Holter-results the interobserver variability of measured parameters (e. g. arrhythmias) and the system-dependent variables (e. g. reproducibility) have to be recognized. Measuring biologic variables like arrhythmias or symptoms using the Holter method the spontaneous variability of infrequent occurring phenomena has to be taken into account and also their relationship to the recording duration: Infrequent occurring phenomena demonstrate an enormous variability, which could be reduced by lengthening the recording duration beyond 24 hours, especially in the evaluation of an antiarrhythmic therapy to avoid a mimicked therapeutic effect. In symptomatic patients their symptoms can be related to arrhythmias or not if an ECG will be recorded during a typical symptomatic period. This depends on the frequency and on the duration of the symptoms, so that other methods than Holter-monitoring should be considered like event-recording, ECG-telephone-telemetry or electrophysiological investigations. In summary the variability of phenomena captured by the Holter method (e. g. arrhythmias, symptoms) is a major factor, which has to be taken into account to avoid unsatisfactorial use of the Holter method.

At present the Holter method (HM) is a frequently used investigational procedure in the clinical routine. It was the aim of a prospective study to evaluate the HM from the user's point of view. Therefore a questionnaire was attached to each analysis report including two main questions, which should be answered by the referring physician: Does the analysis result fulfill the consumer's needs? What consequences are drawn due to the HM results? Among 675 questionnaires returned to the laboratory 75% of the referring physicians felt satisfied by the HM result. Disappointments were predominantly related to too infrequently occurring episodes, which did not appear during one 24-hour recording period. Evaluation of therapy (89%), recording prior to antiarrhythmic therapy (84%) and quantification of well-known arrhythmias were the most successful indications of HM. The tremendous daily variability of infrequent symptoms or arrhythmias were the main causes for unsatisfactory results. A successful HM led predominantly to therapeutic consequences (begin, continuation, change or withdrawal of anti-arrhythmic drugs). In 25% HM was not followed by further therapeutic or diagnostic consequences, so that the indication for the HM should be reevaluated! Diagnostic consequences included repeated HM, ECG-Telephone-Transmission consequences heart catheterisation or electrophysiological procedures. In summary the Holter method satisfies the physician's demands if the expectations do not exceed the limitations of the method.