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Conduction defects do not preclude the usefulness of late potentials in identifying patients with sustained ventricular tachycardia
SELECTED ABSTRACTS
Session Cl - Surface Mapping (Cl-2) Conduction Defects Do Not Preclude the Usefulness of Late Potentials in identifying Patients with Sustained Ventricular Tachycardia. Thomas Buckingham, Chris Thessen, Sanjay Ghost, Denise Janosik, Berhard Chaitman, Robert Wiens. St. Louis University, St. Louis, Missouri. Signal-averaged ECG recorded late potentials (LP) are strongly correlated with the clinical occurrence of sustained ventricular tachycardia (VT) in patients (pts) with normal inter-ventricular conduction. We sought to determine the effect of varying degrees of conduction defects (CD) in 133 pts with coronary disease [normal conduction in 93 pts, hemiblock (HB) in 7, IVCD in 18, and BBB in 151 on LPs and on their ability to identify the 31 VT pts. The relative degree of CD was scored and found to be correlated to amplitude (ALP) and duration (DLP) of LP. ANOVA showed that CD had less effect on ALP than DLP and that ALP was a better discriminator of the VT pt in CD subgroups. Stepwise multiple logistic regression of clinical variables, CD score, and signal-averaged EGG parameters revealed that ALP alone identified pts with sustained VT with an accuracy of 76%, sensitivity of 68%. and specificity of 78%. Similar analysis excluding BBB pts gave an accuracy of 76%, sensitivity of 65% and specificity of 77%. We conclude that LP can identify VT pts regardless of CD and that ALP is better than DLP for this purpose.
(Cl-6) Thresdimentionai Computer Simulation of Depolarization and Repolarization Processes Under Arbitrary Heart Conditions Masanori Aoki, Yoshiwo Okamoto, Toshimitsu Musha, Ken-ichi Harumi. Department of Applied Electronics, Tokyo Institute of Technology, Japan. A 3-dimensional computer model simulating the ventricular depolarization and repolarization in a human heart is presented. Approximately 50,000 cell units arranged in the cubic close- packed structure compose the ventricles. The conduction system is introduced, which consists of the bundle branches and the Purkinje fibers. To determine the activation time of each unit, the propagation process of the excitation front in the ventricles is simulated. The excitation propagates along the bundle branches to the Purkinje system and into the ventricles isotropically from the endocardium to the epicardium. A different action potential waveform is assigned to each unit. The spatial gradient of the action potentials are regarded as electric sources in the myocardium. The heart model is mounted in a homogeneous human torso model. 344 nodal points are arranged on the torso surface where potentials which are generated by the timevarying dipoles during the QRS-T periods are evaluated by means of the boundary element method. The resulting electrocardiogram, the vectorcardiogram, and the body surface potential map are in good agreement with the observations. In the present model, any type of.anomaly such as bundle branch block and myocardial infarction can be taken into account even if different kinds of anomalies are combined.
(Cl-4) Body Surface lsochrone Maps in Predicting Ventricular Arrhythmias in Patients with Myocardial lnfarctlon Kozue Ikeda, lsao Kubota, Kanji Hanashima, Tsuyoshi Konta, Kai Tsuiki, Shoji Yasui. Yamagata University, Yamagata, Japan. The clinical significance of body surface isochrone maps was investigated in 26 patients with previous myocardial infarction, and was compared with signal-averaged ECG late potentials. Body surface isochrone maps were constructed from VAT (the time from the onset of QRS to the peak of R) of each simultaneously recorded 87 body surface unipolar ECGs. Signal averaged lOO- 300Hz filtered ECGS were recorded by MAC1 (Marquette Co), and late potentials (LP) were considered significant lasting over 20 msec. On the isochrone maps, abnormal delay of the ventricular activation (D) was found in 19 pts. Ejection fraction, the incidence of Lown grade 4a and 4b VPC, LP and episodes of sustained VT (susVT) of the D+ group and the D- group were: N EF(%) VPC(4a,b) LP susVT D+ 19 34k15” 8(42%) 9(47%) 3(16%) ‘peO.05 D7 57&l 3” 2(29%) 0( 0%) 0( 0%) The D+ group had lower EF and a higher incidence of VPC, LP and sustained VT than the D- group. It is supposed that D indicates delayed activation of the surviving myocardium in the infarcted area. We conclude that isochrone maps will be a useful method to predict lifethreatening ventricular arrhythmias in patients with previous myocardial infarction. J. ELECTROCARDIOLOGY
20(l),
1987
Session Dl: Arrhythmias/Elsctrophysiology (Dl-1) ECG Spectral Analysis and Heart Ventricular Fibrillation Prognostics George I. Sidorenko, Dmitry G. Laziuk, Anatoly P. Vorobiev, Alexander V. Frolov, Tamara P. Kurtasova, Eugene V. Belogortsev. Byelorussian Research Institute of Cardiology, Minsk, USSR. The microcomputer-based system was develped to control cardiac rhythm activity using spectral analysis techniques. ECG power spectrum deviations pertaining to transition from normal rhythm to ventricular fibrillation (VF) and sinus rhythm re-establishment were examined in 16 rats during CaCl2 infusion and in 10 pts under the extracorporeal circulation and cardioplegia. Thus, it is revealed that in pts when the moment of VF approaches the number of harmonics (H) in the ECG power spectrum with amplitudes of more than 1115 of maximal one decreases from 12.5+2.0 to 5.6M.Q (P
Session Cl - Surface Mapping (Cl-2) Conduction Defects Do Not Preclude the Usefulness of Late Potentials in identifying Patients with Sustained Ventricular Tachycardia. Thomas Buckingham, Chris Thessen, Sanjay Ghost, Denise Janosik, Berhard Chaitman, Robert Wiens. St. Louis University, St. Louis, Missouri. Signal-averaged ECG recorded late potentials (LP) are strongly correlated with the clinical occurrence of sustained ventricular tachycardia (VT) in patients (pts) with normal inter-ventricular conduction. We sought to determine the effect of varying degrees of conduction defects (CD) in 133 pts with coronary disease [normal conduction in 93 pts, hemiblock (HB) in 7, IVCD in 18, and BBB in 151 on LPs and on their ability to identify the 31 VT pts. The relative degree of CD was scored and found to be correlated to amplitude (ALP) and duration (DLP) of LP. ANOVA showed that CD had less effect on ALP than DLP and that ALP was a better discriminator of the VT pt in CD subgroups. Stepwise multiple logistic regression of clinical variables, CD score, and signal-averaged EGG parameters revealed that ALP alone identified pts with sustained VT with an accuracy of 76%, sensitivity of 68%. and specificity of 78%. Similar analysis excluding BBB pts gave an accuracy of 76%, sensitivity of 65% and specificity of 77%. We conclude that LP can identify VT pts regardless of CD and that ALP is better than DLP for this purpose.
(Cl-6) Thresdimentionai Computer Simulation of Depolarization and Repolarization Processes Under Arbitrary Heart Conditions Masanori Aoki, Yoshiwo Okamoto, Toshimitsu Musha, Ken-ichi Harumi. Department of Applied Electronics, Tokyo Institute of Technology, Japan. A 3-dimensional computer model simulating the ventricular depolarization and repolarization in a human heart is presented. Approximately 50,000 cell units arranged in the cubic close- packed structure compose the ventricles. The conduction system is introduced, which consists of the bundle branches and the Purkinje fibers. To determine the activation time of each unit, the propagation process of the excitation front in the ventricles is simulated. The excitation propagates along the bundle branches to the Purkinje system and into the ventricles isotropically from the endocardium to the epicardium. A different action potential waveform is assigned to each unit. The spatial gradient of the action potentials are regarded as electric sources in the myocardium. The heart model is mounted in a homogeneous human torso model. 344 nodal points are arranged on the torso surface where potentials which are generated by the timevarying dipoles during the QRS-T periods are evaluated by means of the boundary element method. The resulting electrocardiogram, the vectorcardiogram, and the body surface potential map are in good agreement with the observations. In the present model, any type of.anomaly such as bundle branch block and myocardial infarction can be taken into account even if different kinds of anomalies are combined.
(Cl-4) Body Surface lsochrone Maps in Predicting Ventricular Arrhythmias in Patients with Myocardial lnfarctlon Kozue Ikeda, lsao Kubota, Kanji Hanashima, Tsuyoshi Konta, Kai Tsuiki, Shoji Yasui. Yamagata University, Yamagata, Japan. The clinical significance of body surface isochrone maps was investigated in 26 patients with previous myocardial infarction, and was compared with signal-averaged ECG late potentials. Body surface isochrone maps were constructed from VAT (the time from the onset of QRS to the peak of R) of each simultaneously recorded 87 body surface unipolar ECGs. Signal averaged lOO- 300Hz filtered ECGS were recorded by MAC1 (Marquette Co), and late potentials (LP) were considered significant lasting over 20 msec. On the isochrone maps, abnormal delay of the ventricular activation (D) was found in 19 pts. Ejection fraction, the incidence of Lown grade 4a and 4b VPC, LP and episodes of sustained VT (susVT) of the D+ group and the D- group were: N EF(%) VPC(4a,b) LP susVT D+ 19 34k15” 8(42%) 9(47%) 3(16%) ‘peO.05 D7 57&l 3” 2(29%) 0( 0%) 0( 0%) The D+ group had lower EF and a higher incidence of VPC, LP and sustained VT than the D- group. It is supposed that D indicates delayed activation of the surviving myocardium in the infarcted area. We conclude that isochrone maps will be a useful method to predict lifethreatening ventricular arrhythmias in patients with previous myocardial infarction. J. ELECTROCARDIOLOGY
20(l),
1987
Session Dl: Arrhythmias/Elsctrophysiology (Dl-1) ECG Spectral Analysis and Heart Ventricular Fibrillation Prognostics George I. Sidorenko, Dmitry G. Laziuk, Anatoly P. Vorobiev, Alexander V. Frolov, Tamara P. Kurtasova, Eugene V. Belogortsev. Byelorussian Research Institute of Cardiology, Minsk, USSR. The microcomputer-based system was develped to control cardiac rhythm activity using spectral analysis techniques. ECG power spectrum deviations pertaining to transition from normal rhythm to ventricular fibrillation (VF) and sinus rhythm re-establishment were examined in 16 rats during CaCl2 infusion and in 10 pts under the extracorporeal circulation and cardioplegia. Thus, it is revealed that in pts when the moment of VF approaches the number of harmonics (H) in the ECG power spectrum with amplitudes of more than 1115 of maximal one decreases from 12.5+2.0 to 5.6M.Q (P