Kohji Hiyamuta

Disappearance of giant negative T waves in patients with the Japanese form of apical hypertrophy

OBJECTIVES The present study investigated the long-term changes in the electrocardiographic (ECG) hallmarks of the Japanese form of apical hypertrophy. BACKGROUND Giant negative T waves and tall R waves in the left precordial leads are the ECG hallmarks of the Japanese form of apical hypertrophy. However, the long-term course is largely unknown. METHODS Twenty-nine patients with apical hypertrophy (26 men, 3 women, mean age +/- SD 50.4 +/- 8.2 years) who showed left precordial giant negative T waves (< or = -10 mm) and tall R waves (> or = 26 mm) and spade configuration in the left ventriculogram were followed up for 10.9 +/- 3.7 years. RESULTS The intermediate follow-up ECGs (5 to 9 years) showed disappearance of giant negative T waves in 31% and of tall R waves in lead V5 in 6%. At the long-term follow-up study (> or = 10 years), loss of giant negative T waves increased to 71%, with average T wave negativity in lead V4 or V5 decreasing from -16.5 +/- 5.1 to -6.9 +/- 4.2 mm. These T wave changes were associated with decreases in R wave amplitude in lead V5 from 40.7 +/- 9.6 to 26.1 +/- 13.8 mm, with loss of tall R waves in lead V5 in 38% of patients and development of abnormal Q waves in two patients. CONCLUSIONS During the long-term follow-up of the Japanese form of apical hypertrophy, giant negative T waves disappeared in association with decreases in R wave amplitude in lead V5, indicating that these ECG hallmarks are clinical features that evolve progressively during the natural course of the disease.

Assessment of regional wall motion abnormality without contrast medium by digital subtraction angiography using Fourier analysis.

Digital subtraction angiography (DSA) offers an image which is linearly amplified and logarithmically subtracted. Therefore, the method makes it possible to evaluate a small difference in X-ray absorption by the cardiac silhouette during one cardiac cycle, even without using contrast medium. Utilizing this advantage, we have developed a new approach to evaluate regional left ventricutar (LV) function by DSA without contrast medium [1]. Digital subtraction images of the left ventricle with and without contrast medium were obtained in the right anterior oblique projection with a Toshiba Digiformer-X. Using an image-processing computer (Toshiba GMS-55A), LV time-density curves were constructed for one cardiac cycle. Phase analysis was performed using Fourier analysis [2] in order to determine regional LV wall motion abnormality. The pattern of the time-density curve for one cardiac cycle without contrast medium was nearly identical to the LV volume curve with contrast medium (Fig. I). The phase image without contrast medium was comparable to that with contrast medium (Fig. 2). Compared with conventional cineangiography, the diagnostic accuracy of regional wall motion abnormality by phase analysis without contrast medium

Abnormal Throughput Coronary Flow in Syndrome X

To elucidate the mechanism of ST segment depression in patients with syndrome X, myocardial blood flow and myocardial O2 and lactate uptake were evaluated in 25 patients who had exhibited chest pain but had normal coronary arteriograms. Fourteen of the patients had chest pain and ST segment depression in an exercise stress test (SX), while the remaining 11 did not exhibit either of these symptoms (control). Atrial pacing induced significant ST segment depression in all patients with SX and did not do so in controls. There was no evidence of coronary artery spasm produced by intravenous administration of ergometrine maleate in any patients. Myocardial blood flow was measured with a Webster’s thermodilution catheter. Coronary flow reserve was defined as the increase occurring in coronary flow after the administration of intravenous dipyridamole (0.56 mg/kg), divided by coronary flow at rest. After the administration of dipyridamole, the coronary flow reserve was 2.70 in the SX group and 2.90 in the controls; this difference was not significant. During atrial pacing, there was a reduction of myocardial lactate uptake and a rise in left ventricular end-diastolic pressure in the SX group, but not in the controls. Oxygen saturation in coronary sinus blood did not change significantly in the controls, while it rose significantly in SX patients.

Inhibitory Effect of Free Radical Scavengers on Cyclic Flow Variations in Unsedated Dogs with Coronary Stenosis and Endothelial Injury

Severe coronary artery stenosis with endothelial injury in the canine model induces cyclic coronary flow variations (CFVs), which are partially due to spontaneous platelet aggregation and dislodgement at the stenotic site. In the present study, we used anesthetized open-chest and unsedated closed-chest dogs with CFVs to investigate whether oxidative metabolic burst (hydrogen peroxide generation) occurred in neutrophils during CFVs and whether CFVs were attenuated by superoxide dismutase (SOD) and catalase. CFVs were produced by placing a cylindrical constrictor on the left anterior descending coronary artery (LAD). LAD blood flow was monitored by means of a Doppler flow probe placed proximally to the constrictor, and the severity of CFVs was expressed by both the frequency of CFVs and mean LAD blood flow. Hydrogen peroxide generation in neutrophils was measured by flow cytometry, using single cell analysis, and was expressed as the mean fluorescence intensity of 2’, 7’-dichlorofluorescein. Dogs received an intravenous infusion of saline (n = 8), SOD (5 mg/kg, n = 7), catalase (5mg/kg, n = 7), or a combination of SOD and catalase (same doses, n = 7). Although the mean fluorescence intensity did not change in sham-operated dogs without CFVs (61.7 ± 15.8 to 60.4 ± 11.8; NS), the intensity in the dogs with CFVs was significantly increased during CFVs (62.2 ± 13.7 to 79.8 ± 9.8; P < 0.005). These results indicate that hydrogen peroxide is generated in neutrophils.

Functional myocardial perfusion imaging by digital subtraction coronary arteriography: Comparison of contrast decay rates in normal and ischemic myocardium

Recent advances in computer technology have enabled the generation of time-density curves of myocardial contrast medium after injection into the coronary artery, using digital subtraction angiography (DSA). Utilizing this advantage, we have described a new technique to assess regional myocardial blood flow in computerized washout analysis of the timedensity curve [1, 2]. T~/2, the contrast decay half-life derived by this technique, showed a good linear correlation with great cardiac vein flow measured by the thermodilution method and a curvilinear relationship with percentage stenosis of the left anterior descending coronary artery (LAD), as shown in Fig. 1. Therefore, T~/2 values proved to be a valuable index of regional myocardial blood flow. In the present study, we have further developed a functional imaging of T~/2 values to visualize the regional myocardial blood flow. After injecting the contrast medium into the LAD, a serial myocardial image was obtained for 20 s in the right anterior oblique projection and this image was then enhanced digitally with the DSA apparatus (TOSHIBA Digiformer X). It was then transmitted to the image-processing computer (TOSHIBA GMS-55A) and was sequentially digitized into a 64 x 64 pixel matrix window. The epicardial outline was drawn by an observer using a computer-aided outlining technique, and a time-density curve of each pixel was generated in the myocardium perfused by the LAD. The descending slope of the time-density curve was fitted to a monoexponential function with a standard least-square method (Fig. 2). The functional image was constructed to present the absolute value of the exponential decay rate constant of the respective pixel in one of four different colors--red, yellow, green, and blue. The exponential decay rates