Koichi Komaki

Clinical utility of negative contrast intravascular ultrasound to evaluate plaque morphology before and after coronary interventions

Although intravascular ultrasound (IVUS) is used for evaluation of plaque volume and lumen size as well as detection of vessel wall structures after catheter-based interventions, differentiation between the lumen and plaque structures can be difficult. This study attempted to evaluate the efficacy of negative contrast IVUS imaging for assessment of vessel wall morphology after coronary interventions. IVUS studies were performed in 67 lesions in 66 patients before and after coronary interventions. After the baseline ultrasound imaging run, warm 5% glucose solution was injected manually through the guiding catheter into the coronary artery to washout blood from the lumen to avoid speckled reflections from red blood cells (negative contrast). Quantitative measurements were obtained and plaque morphology was assessed for the presence and extent of medial dissections and intimal flaps. There was no difference in each quantitative parameter between baseline images and negative contrast images. The vessel wall boundary was clearly delineated from the lumen, which was defined as effective negative contrast in 51 of 67 lesions (76%). The baseline images revealed plaque dissection in 9 lesions (18%) and an intimal flap in 13 lesions (25%). In addition, 4 dissections (8%) and 16 intimal flaps (31%) were visualized during the infusion of negative contrast. Additional treatment was performed in 4 lesions (8%) based on the images with negative contrast. Negative contrast IVUS was more sensitive in demonstrating a plaque fracture than were baseline images. This method is useful for enhancing the diagnostic capability of IVUS imaging and may influence the decision-making process during interventional procedures.

Intra-QRS high-frequency ECG changes with ischemia: Is it possible to evaluate these changes using the signal-averaged holter ECG in dogs?

The purpose of this experiment is to study the possibility of intra-QRS high-frequency electrocardiographic (HFECG) changes for the evaluation of and recovery from myocardial ischemia in both the time-domain and spectral-turbulence analyses on the signal-averaged ECG using the Holter ECG monitoring (Holter SAECG) system. A balloon catheter was inserted into the left anterior descending coronary artery (LAD of 8 mongrel dogs and was maintained inflated for 2 hours to occlude the LAD and then was deflated to allow for reperfusion. The cardiac signal from the three orthogonal leads of the surface ECG (X, Y, and Z) was recorded and analyzed with a Del Mar Avionics (model 459, Irvine, CA) recorder and analyzer (model 563). The Holter SAECG was assessed before the LAD occlusion phase (control), during the coronary occlusion phase (ischemia), after the reperfusion phase (recovery). To evaluate intra-QRS ECG changes in the time-domain analysis, root-mean-square (RMS) voltage of the entire QRS in 40-250 HZ (40 RMS), 100-250 Hz (100 RMS), and 150-250 Hz (150 RMS) were studied and the vector magnitude of the QRS was depicted. In the spectral-turbulence analysis and spectrocardiogram to study the discordance of the ECG wave front velocity by fast Fourier transformation analysis, the interslice correlation mean (IC mean) and interslice correlation standard deviation (IC SD), which were calculated as the mean and standard deviation of the Pearson correlation coefficient of each time slice with its neighbor, were investigated. In the time-domain analysis, the LAD occlusion by balloon catheter at ischemia produced a reduction in 40 RMS, 100 RMS, and 150 RMS, while a restoration was seen at recovery in 40 RMS and 100 RMS. In the spectral-turbulence analysis, LAD occlusion at ischemia caused a decrease in IC mean and an increase in IC SD. The waveform of the vector magnitude and the spectrocardiogram seen at control showed changes with ischemia and was restored at recovery with the coronary reperfusion. It was thought possible to capture the intra-QRS HFECG changes that occur during myocardial ischemia and recovery from it in the time-domain analysis and spectral-turbulence analysis on the Holter SAECG system in spite of the limitation of this methodology. To evaluate myocardial ischemia and recovery, this method should be useful clinically.

Development of new V(z) curve technique for soft materials

The present article reports a technique to characterize small portions in the order of a few micron of a soft anisotropic material. The heart muscle was selected for specimen as an example of the soft material. The heart muscle was cut by a microtome and coated on a substrate. The thickness of the specimen was substantially 3 micrometer. For the substrate, fused quartz was used because its elastic properties are known and stable. The spherical acoustic lens was used to determine the position for the measurement. Considering the anisotropy of the specimen, the cylindrical lens was used to measure velocities of the Rayleigh waves propagating within the specimen. The frequency of 400 MHz was used for both the visualization and the measurement. The generation of the Rayleigh waves in the above conditions was confirmed by numerical calculations based on the wave propagation theory for layered media. As a result, the variation of the velocities representing the anisotropy of elastic properties were obtained and found to be about 7%.

Kampo Medical Education for University Students of Health Education

学校や一般社会で健康教育活動を将来担う大学生を対象として，漢方医学についての講義を行う機会があった。このような学生に対する漢方医学教育の目標の設定は検討されていない。我々は漢方医学の必要性を理解し，将来これに関する適切な助言ができることを目標として講義を行った。講義の前後のアンケート調査を検討すると，漢方医学に関する我々の考えている望ましい認識は講義前の58.0 ± 15.4％から講義には88.5 ± 10.2％と増加した。現在行われている漢方医学の有用性に関しては，極めて有用，あるいは有用という認識に関して，講義前は58.4％であったが，講義後には95.9％となった。講義により漢方医学に関する充分な認識にもとづいて，将来，彼らが学校や社会において，漢方医学に関しても適切な健康教育活動を行うことが期待される。