Vectorcardiographic evaluation of myocardial infarct size: departure parameters are superior to conventional spatial parameters.

To determine whether the departure parameters derived from a "departure loop" of a vectorcardiogram are more accurate than conventional spatial parameters in evaluating myocardial infarct size, 74 patients with first-onset myocardial infarction (MI) were studied. The correlation between the departure parameters (amplitudes in scalar leads of the departure loop) and the percent defect volume of thallium myocardial scintigrams (%DV) was compared with that of the spatial parameters (magnitude, azimuth, and elevation of the original QRS loop). In anteroseptal MI, the amplitude of a 20-msec vector in the z-axis and the azimuth of a 30-msec vector (H30) were significantly correlated with %DV (r=0.783, p<0.001 and r=0.572, p<0.05). In anteroseptal MI with involvement of the lateral wall, the amplitude of a 30-msec vector in the x-axis and H30 showed significant correlation with %DV (r=0.802, p<0.001 and r=0.772, p<0.01). In inferior and inferoposterior MI, the amplitude of a 30-msec vector in the y-axis and the elevation of a 30-msec vector were significantly correlated with %DV (r=0.920, 0.891, p<0.001 and r=0.871, 0.678, p<0.01, respectively). In conclusion, the departure parameters are more accurate than the spatial parameters for evaluation of myocardial infarct size.

[New index for prediction of the patients prone to ventricular arrhythmias after acute myocardial infarction].

Recently late potential (LP) has been evaluated using signal averaged electrograms in order to predict the patients prone to the ventricular arrhythmias such as ventricular tachycardia (VT) or ventricular fibrillation (VF). However, the predictive accuracy was not satisfactory in clinical use. Therefore some new approach was expected. We tried to find a new index to predict the susceptibility to ventricular arrhythmias using frequency analysis by fast Fourier transformation technique (FFT). Fragmented electrograms are elucidated to be present through QRS complex beside the terminal portion of QRS and ST segment by Cain et al. Eighty-seven body surface electrograms were analyzed by FFT, and the power spectral distribution of specific band width of 25-50 Hz was evaluated. Late potential was also obtained by ordinary technique. The patients after acute myocardial infarction were classified into 5 groups according to Lown's grade; group 1 (grade 0.1), group 2 (grade 2), group 3 (grade 3,4A) and group 4 (grade 4B, non sustained VT), and group 5 (grade 4B, sustained VT/VF). The body surface distribution of 25-50 Hz were classified into 3 types; type A (almost equal two maxima), type B (unequal two maxima) and type C (single maximum). Types A & B were frequently observed, but type C was never seen in high risk group (group 4 and 5). Predictive accuracy of VT/VF was 89.2% by type A and 66.7% by LP. The combination of the two criteria improved the predictive accuracy of VT/VF up to 92.9%.(ABSTRACT TRUNCATED AT 250 WORDS)

[A case of brain stem encephalitis complicated with bifascicular block caused by rubella virus].

We reported a case of a 29-year-old man who had been in good health until contracting brain stem encephalitis due to a rubella virus 5 years previously, at which time the ECG revealed complete right bundle branch block and right axis deviation. An ECG obtained 6 months earlier had been within normal limits. Since yearly health checkups continued to show the same abnormalities, the patient was admitted for closer examination. At the time of admission, physical findings and blood tests revealed no abnormalities. No cardiomegaly nor pulmonary congestion was observed on chest X-rays either at the time of the original illness or at this time. An endomyocardial biopsy specimen obtained from the right ventricle revealed size variation of cardiac myocytes, moderate disarrangement, and mild myocardial interstitial fibrosis, indicative of post-myocarditic changes. The above findings suggest that bifascicular block (right bundle branch and posterior fascicle) appeared at the time of the rubella virus infection, in the pathogenesis of which the involvement of myocarditis was strongly suspected. Some patients developing myocarditis do not manifest cardiac symptoms such as heart failure. In these cases, conduction disturbances are the sole sequelae. To differentiate pathogenesis in such cases, endomyocardial biopsy was thought to be of value.

Experimental study on significance of QRS area map--comparison with VAT map.

The QRS area map, which is obtained by time integration of the QRS potential, is assumed to correlate with the ventricular activation time (VAT) map. Using 16 mongrel dogs, the QRS area map and VAT map from cardiac and body surface were compared during sinus rhythm and left and right ventricular endocardial pacing. The cardiac surface QRS area map resembled the cardiac surface VAT map, and it was considered useful to estimate the excitation sequence. The body surface QRS area map localized the stimulus site more easily during pacing than the body surface VAT map. Therefore, it was considered useful to determine the site at which a ventricular extrasystole occurs. The QRS area map proved to be more reproducible than the VAT map.

[The effects of intravenous urokinase administration in patients with acute myocardial infarction].

The effects of intravenous urokinase administration were assessed in patients with acute myocardial infarction (AMI). Of 146 patients with AMI, 101 were admitted within 12 hours of onset of chest pain, and classified in four groups according to the method of administering urokinase. PTCR group (15 cases); PTCR was performed within six hours of onset, using less than 960,000 I.U.; Group A (20 cases); 1.5 million I.U. administered in one hour or 960,000 I.U. in 30 min; Group B (48 cases); 240,000 I.U. in two hours; and 4) Group C (18 cases); 240,000 I.U. in 12 hours. In groups A, B and C, urokinase was administered intravenously. The remaining 45 patients did not receive urokinase, and served as a control group. In the chronic stage, infarction-related coronary arteries were patent at rates of 93% in the PTCR group, 82% in group A, 76% in group B, 62% in group C, and 46% in the control group. In the PTCR group and in group A, alpha 2-plasmin inhibitor showed a steep decline to the lowest level on the day after urokinase administration, as did the summation of elevation of ST segments in conventional twelve-lead electrocardiograms. Peak CK times, which represent the duration (hours) from onset to the peak serum CK value increased in the following order: 13.3 +/- 4.8 in the PTCR group, 17.3 +/- 4.9 in group A, 17.3 +/- 6.9 in group B, 20.7 +/- 6.7 in group C and 22.5 +/- 6.4 in the control group. These data suggest early recanalization of occluded coronary arteries in the group A, and intravenous administration of high doses of urokinase in the early phase of AMI seemed to contribute to salvage the ischemic myocardium. However, assessment of ventricular wall motion by two-dimensional echocardiography failed to confirm appreciable improvement in the PTCR group and group A in comparison with the other groups.