Tsuyoshi Anan

Arrhythmia analysis by successive RR plotting.

A successive RR interval plot was developed to analyze arrhythmia. The plot consisted of a set of points with the x-value of (N)th RR interval and the y-value of (N + 1)th RR interval. This method was applied in the arrhythmia analysis of Holter electrocardiograms obtained from 35 patients. In the analysis of ventricular premature contractions (VPCs) this method was useful not only in detecting VPCs but also in demonstrating coupling interval-dependent characteristics of VPCs. In the analysis of atrial fibrillation the successive RR plot enabled the authors to estimate the functional refractory period of the atrioventricular conduction. In conclusion, despite its simplicity, the successive RR plot was found to be powerful in analyzing arrhythmia. Specifically, the potential to analyze integrally the coupling interval-dependent properties of various types of arrhythmia makes it attractive as a clinical tool.

Differentiation between aberrant ventricular conduction and ventricular ectopy in atrial fibrillation using RR interval scattergram.

BackgroundDifferentiation between aberrant ventricular conduction and ventricular ectopy during atrial fibrillation (AF) is of etiologic, prognostic, and therapeutic importance. We developed a noninvasive technique to diagnose aberrant ventricular conduction and ventricular ectopy in AF. Methods and ResultsWe studied the Holter ECGs of 34 patients with paroxysmal AF and 62 patients with chronic AF. In all the patients, frequent wide QRS complexes were observed, and 32 patients were shown by electrophysiological examination to have ventricular ectopies or aberrant ventricular conductions. We obtained the RR interval scattergrams by plotting sequential pairs of RR intervals. Each point has the (n)th RR interval as its × value and the (n+1)th RR interval as its y value. The irregularity of the RR intervals in AF resulted in widely scattered points delineated by the envelope along the axes. The y value of the envelope along the × axis indicates the shortest coupling interval to the preceding RR interval. Therefore, this curve defines the functional refractory period of atrioventricular conduction. The scattergram of the RR interval pairs immediately preceding the aberrant conduction (coupling points of aberrant conduction) specifically distributed along the envelope. In contrast, the coupling points of ventricular ectopies showed different distributions that had no relation to the envelope. That is, it included three typical patterns, ie, linear distribution below the envelope, linear distribution partially overlapped in the area of normal AF conduction, and chaotic distribution in the AF area. None of the scattergrams of ventricular ectopies showed curvilinear distribution along the envelope as aberrant conduction did. The specific distribution of the aberrant conduction on the RR interval scattergram suggested that aberrant conduction in AF could result from the difference of refractory periods between the AV node and bundle branch block. ConclusionsWe conclude that the RR interval scattergram makes it possible to differentiate between aberrant ventricular conduction and ventricular ectopy in atrial fibrillation, and thus, it is a useful noninvasive clinical tool.

Reflex heart rate and blood pressure changes during ST segment elevation in patients with variant angina

Responses of heart rate and blood pressure to transient myocardial ischemia were analyzed in patients with variant angina. Heart rate changes during ST segment elevation were examined by means of a Holter ECG monitoring system. All 27 ST segment elevations from 10 patients with anterior ischemia were accompanied by an increase in heart rate by 12 +/- 2 bpm (mean +/- SEM, p less than 0.001) at peak ST segment elevation. With inferior ischemia in nine patients, heart rate decreased significantly by 4 +/- 1 bpm (n = 28, p less than 0.001). However, 9 of these 28 ST segment elevations showed a biphasic response of heart rate, that is, an initial increase and subsequent decrease. Such heart rate changes were not different between ST segment elevations with and without chest pain. With chest pain systolic blood pressure rose in anterior ischemia by 42 +/- 5 mm Hg (n = 10, p less than 0.001) but fell in inferior ischemia by 22 +/- 8 mm Hg (n = 7, p less than 0.05). We conclude that a different cardiovascular reflex occurs in response to inferior versus anterior ischemia and it is independent of chest pain.

Prevalence of ventricular tachycardia in patients with different underlying heart diseases: A study by Holter ECG monitoring

Twenty-four-hour Holter ECGs were recorded in 1089 patients. Ventricular tachycardia (VT) was observed in 184 tapes obtained from 81 patients (73 men and 8 women). Underlying heart diseases were present in 72 patients and no organic heart diseases were found in nine patients. The analysis of continuous 1-hour rhythm strips immediately before VT revealed that, in ischemic heart disease and hypertrophic cardiomyopathy, there was no correlation between the incidence of VT and the number or complexity of premature ventricular complexes (PVCs) within 1 hour before VT. In contrast, frequent or multiform PVCs were often observed during the pre-VT period in the patients with rheumatic heart disease or dilated cardiomyopathy. These findings suggest that the mechanism of VT may be different among the various underlying heart diseases. In addition, the mode of initiation of VT was evaluated. Only few episodes of VT occurred with the prematurity index value smaller than 1.0 or the vulnerability index value greater than 1.1. The correlation between the rate of VT and the preceding sinus rate was not significant, and the correlation between the rate of VT and the coupling interval of VT was weak. These facts suggest that the malignancy of VT, represented by the rate of VT, cannot be predicted by the preceding sinus rate or by the coupling interval of VT.

A Holter-tape analyzer employing circuits for calculation of correlation coefficients.

An analyzer for ventricular premature contraction (VPC) arrhythmias was developed. At 60 times real time, the analyzer processes the Holter tape in which the long-term ambulatory electrocardiogram was recorded. Template matching algorithm using Pearson product-moment correlation coefficient is employed. A microprocessor controls the analyzer. Circuits for calculation of correlation coefficients were developed to support insufficient computing speed of the microprocessor. Evaluation study shows that the sensitivity for detecting the normal QRS complexes and the VPCs were 98.9% and 99.4%, and that the specificity for these were 97.5% and 98.4%. Algorithm for high-speed calculation of correlation coefficients is also considered.