Biomedical subjects
Publications and source records attributed to S Kyo.
This article reports on the technical aspects of an online real-time biplane transesophageal echocardiographic imaging system and of a single-matrix, phased-array transducer capable of transverse and longitudinal scanning.
To quantitatively assess flow area or kinetic energy in color flow mapping (CFM), angle correction, which has been totally ignored using current systems, is now considered indispensable. To reconstruct flow images using angle-corrected velocity mapping, we incorporated a personal computer (NEC PC-LT) in the cine-memory of a CFM system (Aloka SSD-870). To demonstrate the effect of angle correction on CFM, the maximum left ventricular diastolic flow images were obtained in seven normal adults using the apical long-axis views where the angle of incidence was less than 10 degrees, and the parasternal long-axis view, where the angle of incidence was between 40 and 60 degrees. A 3.5 MHz probe with a 4 KHz pulse repetition frequency at a frame rate of 10/sec was used. Flow area and kinetic energy of the original and angle correction images in the aliased parts and the total flow areas were calculated and expressed as percent values of the control (color correction image of total flow area in the apical view). The total flow area of the original image in the apical view was 96.4% and 87.2% in the parasternal view, or 98.6% by effective angle correction, and the kinetic energy of the original image in the apical view was 94.0% and 58.8% in the parasternal view, or 93.3% by angle correction. In conclusion, although flow area and kinetic energy of the original image in the parasternal view were significantly less than those of the original and the angle correction images in the apical view (p less than 0.05), they could effectively be evaluated by angle correction. Thus, this system can contribute to quantitative assessment of CFM.
To examine the clinical feasibility of color flow mapping Doppler echocardiography (CFM) in diagnosing the patency of internal mammary artery (IMA) grafts, 41 patients who had had coronary bypass surgery were examined by both CFM and coronary angiography (CAG) within one week of the CFM examination. Coronary bypass surgery was performed one to eight months prior to this study, and the average number of bypass grafts was 2.7 +/- 0.7. The patency of the IMA grafts was confirmed in all except one patient by CAG; whereas, the flow in the IMA grafts was clearly visualized in all 22 patients by CFM from the left parasternal echo window. Peak velocities of the IMA graft flow in the 22 patients were 31.7 +/- 12.0 (19-49) cm/sec in diastole and 14.9 +/- 8.5 (5-36) cm/sec in systole. No false positive diagnosis was made in the CFM examination. The sensitivity, specificity, negative predictive value, and positive predictive value of CFM in the diagnosis of IMA graft patency were 55%, 100%, 5.3% and 100% respectively. In conclusion, although the sensitivity of color Doppler still remains relatively low, its specificity in the diagnosis of IMA graft patency is 100%. Thus, color Doppler is expected to be valuable for long-term follow-up of IMA graft patencies.
To determine the clinical advantages of transesophageal color Doppler echocardiography (TEE) for imaging cardiac tumors and left atrial thrombi, 24 cases with intra- or extracardiac masses were examined by transthoracic color Doppler echocardiography (TTE) and TEE before and after cardiac surgery. Five with left atrial myxomas, two with lung tumors, five with mediastinal tumors and 12 with mitral stenosis coexisting left atrial thrombi were included in this study. The echocardiographic findings of the cardiac masses were compared with the surgical findings in all cases. In all of the five cases with left atrial myxomas, the tumors were detected. However, the sites of attachment and a stalk in three cases were not observed by TTE. TEE clearly imaged the left atrial myxomas, and evaluated the size and shape of the tumors, the sites of their attachment and a stalk arising from the interatrial septum, and mobility in four cases, except for one in which there was a broad attachment to the endocardium. Mitral regurgitation was detected in only two cases using the color Doppler mode of TTE, but in all cases using TEE. Both techniques failed to recognize tissue characterization. Among seven cases with secondary cardiac tumors or mediastinal tumors, extracardiac masses were detected in five; however, an intracardiac tumor attached to the interatrial septum and an extracardiac tumor extending to the superior vena cava and an upper part of the right atrium could not be imaged using TTE. TEE detected all tumors at all sites in the heart and vessels, and estimates of their extents were in accord with the operative findings in 17 of 18 sites. One exceptional case had a tumor which extended to the right ventricle. Neither technique could detect infiltration of the heart which was present in five of the seven cases. Multiple left atrial thrombi were observed in eight of 12 cases, resulting in 21 thrombi and they were diagnosed by TEE in six of 12 cases. Thrombi, when attached to the left atrial posterior or inferior walls, were easily detected in four of five cases, but were not identified in four of six and in eight of nine cases at the lateral wall or in the left atrial appendage by TTE. However, TEE detected all thrombi in every site in the left atrium and left atrial appendage in 11 of 12 cases. TEE was thus superior to TTE in detecting cardiac masses, recognizing abnormal flow and estimating anatomical relationship between tumors or thrombi and cardiac structures.(ABSTRACT TRUNCATED AT 400 WORDS)
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To determine whether transesophageal color Doppler echocardiography (TEE) is useful for the early diagnosis and surgical intervention in acute aortic dissection, 57 serial patients with acute aortic dissection were examined. These patients were evaluated by TEE with either the single-plane probe (39 patients) or the biplanar probe (18 patients) just after admission. The intimal flap was detected in all patients, and there were 18 patients with type A dissection and 39 patients with type B dissection. The entry was visualized in 83% of type A dissection cases and in 90% of type B dissection cases. In two of 18 patients examined with the biplanar probe technique, the entry was detected in the longitudinal view only. Emergency operations were performed in 18 patients with type A dissection and in 10 patients with ruptured type B dissection. Twenty-nine of 39 patients with type B dissection were treated conservatively. The operative mortality rate of patients with type A dissection was 22%, and that of patients with ruptured type B dissection was 60%. The major advantage of TEE is its ease of application at the bedside or in the operating room, which allows immediate and accurate diagnosis of acute aortic dissection for emergency surgical intervention. Biplanar TEE provides additional acoustic windows, ease of spatial orientation, and more accurate visualization of entry. TEE is a useful and powerful diagnostic tool for acute aortic dissection, and by using this method, one may achieve a more rapid and aggressive surgical approach for patients with acute aortic dissection.
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To assess the effects of coronary vasodilators and exercise on the blood flow dynamics of aortocoronary bypass grafts (ACBG), two-dimensional Doppler echocardiography was performed in 43 consecutive patients with ACBG of the left coronary artery. Doppler velocity signals of 14 internal mammary artery grafts (IMAG) and three saphenous vein grafts (SVG) were imaged in 15 patients using 5MHZ and 7.5MHZ convex-linear Doppler flow probes. Cross-sectional blood flow velocities and graft internal dimensions were continuously measured before and after the sublingual administration of nitroglycerin (0.3 mg) and nifedipine (20 mg), during isometric handgrip and bicycle ergometer exercise tests. 1. Regurgitant flow in isometric contraction time to early systole was observed in 14 of the 15 patients. Pulsatile diastolic blood flow with mean velocity of 14 +/- 6 cm/sec and volume of 49 +/- 25 ml/min was significantly higher than those in systole (7 +/- 7 cm/sec and 8 +/- 7 ml/min) as observed in IMAG and SVG. IMAG showed smaller vessel dimensions, higher flow velocities and lower flow volumes compared with those of SVG. 2. Nitroglycerin and nifedipine increased blood flow volumes (75 +/- 12%, 79 +/- 11%) and velocities (29 +/- 8%, 28 +/- 8%) due to dilatation of graft vessels (18 +/- 3%, 19 +/- 3%). Nifedipine, in contrast to nitroglycerin, induced sustained increases in graft flows. 3. Isometric handgrip and ergometer bicycle exercise tests increased blood flow volumes (34 +/- 9%, 61 +/- 14%) and velocities (31 +/- 11%, 42 +/- 12%) with elevation of double products (22 +/- 14%, 37 +/- 26%). Ergometer bicycle exercise induced similar responses in systole and diastole, whereas isometric handgrip test induced higher ratios of graft flow volume in systole (67 +/- 25%) compared to those in diastole (28 +/- 9%). In conclusion, two-dimensional color Doppler echocardiography is a promising means for the quantitative analysis of blood flow dynamics, assessments of the variable effects of coronary vasodilators and the physiological responses to exercise tests for the aortocoronary bypass graft flow in the early postoperative state.
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To evaluate noninvasively the patency of aortocoronary bypass grafts using the left internal mammary artery (LIMAG), color flow mapping Doppler echocardiography was performed in 23 consecutive patients. There were 22 males and one female. The average number of involved coronary arteries per patient was 2.5 +/- 0.6. The average number of bypassed graft anastomoses was 2.7 +/- 0.9, including 22 isolated LIMAG and one sequential LIMAG. The color flow mapping system used was a linear type 2-D Doppler system (Aloka SSD350) with a convex type transducer. Clear color flow visualization of LIMAG flow was obtained in nine of the 23 patients (39%) studied, with an average peak diastolic velocity of 22.5 +/- 8.7 cm/sec and an average systolic peak velocity of 12.6 +/- 5.7 cm/sec. The coronary angiograms of eight patients were obtained within two weeks after the echocardiographic examinations which demonstrated good graft patency in all LIMAG. Color flow visualization of LIMAG was obtained in four of the eight patients (50%). Although the detection rate was limited, LIMAG flow could be clearly visualized in nearly half the cases studied with stable reproducibility from the transcutaneous echo window. Thus, this technique can be a useful diagnostic means for long-term follow-up of LIMAG and for investigating coronary circulation in the future.
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