-
2011 IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2011, Vancouver, BC, Canada, July 24-29, 2011; 01/2011
-
[show abstract]
[hide abstract]
ABSTRACT: In the previous paper, we proposed the tuning method of PI controller for a plant model described by a first-order lag plus deadtime system based on a desired damping, and demonstrated its effectiveness and limitation by simulation studies. The PI parameters have been adjusted so that their influence on the damping was transparent. It is well known that the derivative action is effective in obtaining the desired damping. In this paper, of particular interest to us is how to tune PID controller to suppress overshoot. In tuning controllers it is often convenient to specify a damping coefficient of the closed system. For PID control, the integral time T<sub>d</sub> and the derivative time Td are kept fixed to degenerate the order of the closed-loop transfer function. This can be easily led to pole-zero cancellation. Thus, the only one parameter of PID controller to be adjusted now becomes the proportional gain k<sub>p</sub>. It can be concluded that the PID controller provides a much better response than the PI controller presented last year. The resultant graphical comparisons document how to give a guide line for tuning of PID controller.
SICE, 2007 Annual Conference; 10/2007
-
M Katayama,
A Yamamuro,
Y Kanzaki,
T Takagi,
K Tamita,
K Yamabe,
T Tani,
K Tanabe,
K Shiratori,
S Morioka, Y Okada
[show abstract]
[hide abstract]
ABSTRACT: Systolic pulmonary venous flow reversal identified by pulsed Doppler echocardiography is useful for the diagnosis of severe mitral regurgitation. The direction of the mitral regurgitant jet in severe mitral regurgitation significantly influences the systolic pulmonary venous flow reversal in an experimental model. This study investigated the influence of the site of mitral valve prolapse on the incidence of systolic pulmonary venous flow reversal in patients with severe mitral regurgitation using transthoracic color Doppler echocardiography.
This study included 59 consecutive patients with severe mitral regurgitation (regurgitant fraction > 50%) due to mitral valve prolapse. Exclusion criteria were left ventricular ejection fraction < 45%, non sinus rhythms, associated aortic valve disease, bileaflet prolapse, and inadequate Doppler recordings. Right upper pulmonary venous flow was recorded and regurgitant fraction of mitral regurgitation measured by transthoracic color Doppler echocardiography. The sites of mitral valve prolapse were confirmed at operation in all patients.
The incidence of systolic pulmonary venous flow reversal was 78% (14/18) in the patients with anterior leaflet prolapse, 82% (9/11) in the patients with medial commissure prolapse, 75% (12/16) in the patients with posterior middle scallop prolapse, 20% (2/10) in the patients with posterior medial scallop prolapse, and 25% (1/4) in the patients with posterior lateral scallop prolapse. There were no significant differences in regurgitant fraction between the five groups. The incidence of systolic pulmonary venous flow reversal was significantly lower in the patients with posterior medial scallop prolapse compared to the other sites of mitral valve prolapse (p < 0.01).
Assessment of the severity of mitral regurgitation by systolic pulmonary venous flow reversal using transthoracic color Doppler echocardiography may be underestimated in patients with prolapse of the posterior medial scallop.
Journal of Cardiology 01/2002; 38(6):319-25. · 1.28 Impact Factor
-
New Generation Comput. 01/2000; 18:87-88.
-
[show abstract]
[hide abstract]
ABSTRACT: The purpose of this study was to assess coronary flow characteristics in patients with chronic mitral regurgitation (MR).
Coronary flow reserve (CFR) has been reported to be restricted in cases with left ventricular (LV) volume overload caused by aortic regurgitation and increased LV preload.
The study populations consisted of 31 patients with nonrheumatic chronic MR. Eleven with chest pain and normal coronary arteries served as control subjects. Phasic coronary flow velocities were obtained in the proximal segment of the angiographically normal left anterior descending coronary artery at rest and during hyperemia (0.14 mg/kg/min adenosine infusion intravenously) using a 0.014-in. (0.036 cm), 15-MHz Doppler guide wire. Coronary flow reserve was obtained from the ratio of hyperemic/baseline time-averaged peak velocity (APV). Thirteen cases who underwent mitral valve reconstructive surgery were also studied 1 month after surgery.
Compared with control subjects, CFR was significantly reduced in cases with MR (2.1+/-0.5 vs. 33+/-0.6, respectively, p < 0.01) because baseline APV was significantly greater (28+/-8 vs. 19+/-6 cm/s, respectively, p < 0.01), although maximal hyperemic APV was not significantly different (56+/-14 vs. 61+/-16 cm/s, respectively, p = NS). Significant correlations were obtained between CFR and LV end-diastolic pressure (LVEDP) (r = 0.70, p < 0.01), LV mass index (r = 0.42, p < 0.01), LV end-diastolic volume (r = 038, p = 0.04) and MR volume (r = 0.39, p = 0.03), and stepwise regression analysis showed LVEDP was the most important determinant of CFR in MR (r2 = 0.49, p < 0.0001). This restricted CFR improved significantly after mitral valve reconstructive surgery (2.1+/-0.5 vs. 3.1+/-0.6, respectively, p < 0.01) because of reduction of baseline APV (28+/-8 vs. 21+/-8 cm/s, respectively, p < 0.01).
Coronary flow reserve is limited in cases with MR because of elevation of baseline resting flow velocity. This reduction of CFR correlates well with increase in LV preload, mass and volume overload, especially with increase in LV preload, and this restricted CFR improves after mitral valve surgery.
Journal of the American College of Cardiology 01/1999; 32(7):1923-30. · 14.16 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Predictability of aorta-related complications and survival was examined in 79 operative survivors of acute aortic dissection. Follow-up was 94.9% complete and totaled 458 patient-years. Actuarial survival was 93 +/- 3% (+/- S.E.) (n = 43) at 5 years, and 74 +/- 8% (n = 13) at 10 years. Survival was significantly lower in patients having neurological complication. Freedom from aorta-related complications was 82 +/- 5% (n = 37) at 5 years, and 67 +/- 8% (n = 11) at 10 years. Multivariate Cox regression analysis identified residual entry and leak on anastomotic site as independent predictors of aorta-related complications. We conclude that in the treatment of acute aortic dissections, reducing the incidence of residual entry and leak on anastomotic site improves long-term outcome.
Kyobu geka. The Japanese journal of thoracic surgery 08/1998; 51(8 Suppl):647-50.
-
The Japanese Journal of Thoracic and Cardiovascular Surgery 05/1998; 46 Suppl:110-2.
-
M Iwai,
K Yoshida,
T Hozumi,
T Akasaka,
T Takagi,
Y Yamaura,
Y Ogata, Y Okada,
T Shomura,
S Morioka,
J Yoshikawa
[show abstract]
[hide abstract]
ABSTRACT: Serial changes in mitral regurgitation after anterior mitral valve repair were examined by transesophageal echocardiography (TEE) in 34 of 86 consecutive patients with pure mitral regurgitation who underwent anterior mitral valve repair from 1987 to 1996. The patients were divided into two groups: 15 patients undergoing mitral repair with polytetrafluoroethylene (PTFE; PTFE group) and 19 undergoing conventional mitral repair without PTFE (non-PTFE group). The PTFE group included 11 men and 4 women with a mean age of 52.1 years. They were followed for mean 22.8 +/- 12.0 months. The non-PTFE group included 12 men and 7 women with a mean age of 53.9 years. They were followed for mean 33.9 +/- 20.4 months. Mitral regurgitation jet areas were observed at the time of operation, 1 month after mitral valve repair, and in the late follow-up period. Regurgitation jet areas were 0.7 +/- 0.7, 1.1 +/- 0.9 and 2.5 +/- 2.1 cm2 in the PTFE group, and 1.1 +/- 1.3, 2.4 +/- 1.7, 4.7 +/- 2.9 cm2 in the non-PTFE group. The jet area was significantly smaller in the PTFE group than in the non-PTFE group at 1 month after operation and in the late follow-up period. Moderate to severe regurgitation was observed in two patients (13.3%) in the PTFE group, and eight patients (42.1%) in the non-PTFE group. Mitral valve repair with PTFE showed better results than conventional mitral valve repair without PTFE during the mean follow-up period of 23 months.
Journal of Cardiology 04/1998; 31(3):159-63. · 1.28 Impact Factor
-
M Iwai,
K Yoshida,
T Hozumi,
T Akasaka,
T Takagi,
Y Yamaura,
Y Ogata, Y Okada,
T Shomura,
S Morioka,
J Yoshikawa
[show abstract]
[hide abstract]
ABSTRACT: The long-term results of mitral valve repair using artificial polytetrafluorethylene (PTFE) chordae were assessed in 61 consecutive patients with pure mitral regurgitation who underwent mitral valve repair with replacement of elongated or ruptured chordae tendineae between 1992 and 1996. There were 36 men and 25 women aged from 14 to 73 years (mean 52.1 +/- 13.8 years). The patients were followed up for between 1 to 73 months (mean 29.3 +/- 17.6 months). Fifty-five patients underwent mitral valve repair of the anterior leaflet and 6 repair of the posterior leaflet. There were two hospital and two late deaths. Actual survival rate at 5 years was 93.1%. Freedom from cardiac events at 5 years was 87.8%. Two patients required reoperation due to hemolysis. There were three occurrences of non-fatal thromboembolism. Although further investigation is necessary in a large population, expanded PTFE sutures are excellent for chordal replacement during mitral valve repair.
Journal of Cardiology 02/1998; 31(1):19-22. · 1.28 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We experienced the case of left atrial myxoma originating from posterior leaflet mitral valve. Mitral valve repair was performed in that case, because of the presence mitral leaflet defect due to removal of the myxoma. Transesophageal echocardiography was a useful tool for perioperative evaluation of the mitral valve and precise localization of the origin of the myxoma.
Kyobu geka. The Japanese journal of thoracic surgery 10/1997; 50(10):866-8.
-
[Zasshi] [Journal]. Nihon Kyōbu Geka Gakkai 04/1997; 45(3):336-7.
-
[show abstract]
[hide abstract]
ABSTRACT: Three-dimensional (3D) echocardiography permits the objective analysis of structures and of pathologic conditions of complex geometry. Multiplane transesophageal echocardiography (TEE) permits 3D image sets of the heart to be produced from multiple 2D images by rotating the transducer, without changing its position. The purpose of this study was to clarify the capability of 3D echocardiography to evaluate the configuration and dynamics of the mitral annulus in patients fitted with an annuloplasty ring.
Twenty patients who underwent mitral valve repair for pure mitral regurgitation (10 with a flexible Duran ring and 10 with a rigid Carpentier ring) were studied. Using a multiplane transesophageal probe, sequential tomographic images were obtained by rotating the transducer at 2 degrees angular intervals around a 180 degrees arc. 3D reconstructions were performed to produce dynamic 3D images of the mitral annulus in a manner that simulated visualization from the left atrium. Mitral annular configuration was assessed from volume-rendered display and extractive 3D imaging. Mitral annular area change was evaluated from selected long-axis cut planes.
The configuration and dynamics of the mitral annulus were visualized by 3D displays. In patients with a Duran ring, the mitral annulus had a non-planar configuration and mitral annular area changed during cardiac cycle (increased in diastole; reduced in atrial and ventricular systole; percentage reduction 25 +/- 2%). In patients with a Carpentier ring, the mitral annulus had a planar configuration and mitral annular area was effectively unchanged during the cardiac cycle.
3D echocardiography using a multiplane transesophageal probe is useful in evaluating the configuration and dynamics of the mitral annulus in patients fitted with an annuloplasty ring.
The Journal of heart valve disease 02/1997; 6(1):43-7. · 0.81 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Mitral valve repair offers many advantages over prosthetic valve replacement, especially in minimizing the risk of thromboembolism. Intraoperative evaluation of residual mitral regurgitation (MR) is important in this procedure. The present study assessed the usefulness of transesophageal echocardiography (TEE) for the intraoperative assessment of residual MR in patients undergoing mitral valve repair. Intraoperative TEE was performed in 102 consecutive patients before and after mitral valve repair in the operating room. The grade of MR was evaluated according to the maximum MR jet area detected by biplane color Doppler TEE (mild: <4 cm2; moderate: 4 < or = < 7 cm2; severe : 7 cm2 < or =). After the first repair, the manual regurgitant test was performed. Excellent results with no or mild MR assessed by the manual regurgitant test were obtained in 101 patients. However, moderate or severe MR was identified in eight of these 101 (7.9%) patients by TEE after weaning from the cardiopulmonary bypass. Consequently, six of these eight patients underwent repeat mitral valve repair and two patients received prosthetic valve replacement. Satisfactory final operative results were obtained in all 101 patients. The eight patients who needed additional operative procedures followed good clinical courses in hospital. TEE 1 month after operation demonstrated no or mild MR in these eight patients. Intraoperative TEE is useful in the evaluation of residual MR after mitral valve repair. This technique provides indications for immediate additional operative procedures, and can reduce the occurrences of congestive heart failure and reoperation in the early stage after mitral valve repair.
Journal of Cardiology 09/1996; 28(3):155-9. · 1.28 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The results of anterior mitral leaflet repair were evaluated by the serial change of mitral regurgitation (MR) using transesophageal echocardiography (TEE) in 24 patients undergoing mitral valve repair for anterior leaflet prolapse during 1988 to 1994, who were examined by TEE immediately after operation, 1 month after operation, and late after operation (mean 15 months). Chordal replacement using polytetra-fluorethylene chordae was performed in 15 patients (PTFE group), and not performed in 9 patients (non-PTFE group). MR jet area late after operation was significantly smaller in the PTFE group than in the non-PTFE group (2.2 +/- 2.3 vs. 4.6 +/- 2.3 cm2, p < 0.05). Moderate to severe MR was observed in four patients (27%) in the PTFE group, and six (67%) in the non-PTFE group late after operation. The thickness of the mitral leaflet before operation was more than 5 mm in all patients with more than moderate MR late after operation in the PTFE group. Chordal replacement using polytetrafluorethylene chordae showed better results compared with conventional mitral valve repair without polytetrafluorethylene chordae over the follow-up period of 15 months.
Journal of Cardiology 07/1996; 27(6):315-9. · 1.28 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A 20-year-old man with a bicuspid valve underwent aortic valvuloplasty for aortic regurgitation. Valvuloplasty was performed according to Cosgrove's method. Intraoperative transesophageal color Doppler echocardiography showed trivial aortic regurgitation after the repair. Peak pressure gradient across the repaired aortic valve was 9.3 mmHg at rest (cardiac output 4.2 l/min, stroke volume 49 ml) and 27.6 mmHg at dobutamine infusion (cardiac output 8.7 l/min, stroke volume 78 ml). The patient was in NYHA class I with no medication after surgery. Valvuloplasty for aortic regurgitation with a bicuspid valve is the surgical procedure of choice.
Journal of Cardiology 02/1996; 27 Suppl 2:85-9; discussion 90. · 1.28 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Mitral valve repair is an important operative procedure for correcting mitral regurgitation (MR). However, serial change of residual MR after operation has not been reported. Serial change of MR after mitral valve repair was evaluated by transesophageal color Doppler echocardiography (TEE). Twenty-six patients undergoing mitral valve repair for MR during 1987 to 1991 were examined by TEE just after operation, 6 months after operation, and late follow-up period (mean 3.7 years). Thirteen patients had a lesion of the anterior mitral leaflet before operation (group A). Thirteen patients had a lesion of the posterior mitral leaflet before operation (group P). The MR area was measured by TEE at each stage after operation. In group A, the MR area at late follow-up increased significantly compared with just after operation (1.1 vs 4.3 cm2, p < 0.001). In group P, the MR area at late follow-up did not increase significantly compared with just after operation (0.6 vs 1.3 cm2, p = NS). In conclusion, MR does not increase after mitral valve repair in patients with posterior mitral valve repair, but MR may increase at late follow-up after operation for anterior mitral valve prolapse.
Journal of Cardiology 02/1996; 27(2):73-76. · 1.28 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Multiplane transesophageal echocardiography provides three-dimensional reconstruction of the mitral annulus from multiple cross-sectional views from a stable transducer position by rotating around a central axis. This study was designed to evaluate the effect of the type of annuloplasty ring on mitral annular configuration and dynamics using three-dimensional reconstruction by multiplane transesophageal echocardiography.
Ten patients who underwent mitral valve repair for pure mitral regurgitation (five patients with flexible Duran ring, five patients with rigid Carpentier ring) and five normal subjects were studied with multiplane transesophageal echocardiography. Three-dimensional configuration of the mitral annulus was obtained from multiple cross-sectional views of multiplane transesophageal echocardiography.
In normal subjects, the mitral annulus had a non-planar configuration and reduced its area in systole. In patients with a Duran ring, the mitral annulus had a non-planar configuration and reduced its area in systole. In patients with a Carpentier ring, the mitral annulus had a planar configuration and the mitral annular area did not change during the cardiac cycle.
Three dimensional reconstruction of the mitral annulus using multiplane transesophageal echocardiography revealed that mitral annular configuration and dynamics are more physiologic in patients with a flexible Duran ring that with a rigid Carpentier ring.
The Journal of heart valve disease 12/1995; 4(6):618-22. · 0.81 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Fourteen patients with mitral regurgitation resulting from infectious endocarditis underwent mitral valve repair between December 1988 and July 1994. There were nine males and five females aged from 14 to 70 years (mean 40.2 +/- 19.7 years). Three patients had active endocarditis. Time between the onset of endocarditis symptoms and surgery ranged from 1 to 24 months (mean 8.3 months). Bacterial findings were Streptococcus in eight patients, Staphylococcus in one, and unknown in five. All macroscopically infected tissue was excised in patients with active endocarditis. Carpentier's reconstructive techniques were mainly used. There were no hospital deaths. Mean follow-up was 29 months and complete. Thirteen patients were in New York Heart Association functional class I and one in class II. There were no late deaths, reoperations, recurrent endocarditis, thromboembolic events, or other valve-related morbidity. We conclude that mitral valve repair is an attractive procedure in patients with mitral regurgitation resulting from infectious endocarditis.
Journal of Cardiology 06/1995; 25(5):243-6. · 1.28 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The objective of this study is to evaluate safety and efficacy of the selective cerebral perfusion (SCP) for an adjunct to perform operation of aortic arch aneurysms. From November 1982 to June 1993, surgical treatment of aneurysm of aortic arch using SCP was performed in 22 patients. The hospital death was accounted in 5 cases (23%), the intraoperative stroke was observed in 3 cases (14%) and these patients died. The cause of intraoperative stroke was cerebral hypoperfusion due to multiple sclerosis of intracranial arteries or insufficient SCP. Variables of an increased operative risk seemed to be older age (over 70 y.o.) and rupture. SCP time more than 120 minutes did not promote the operative risk. Cerebral hypoperfusion was directly responsible for not only intraoperative stroke, but also operative death. Therefore, SCP seems effective and safe if hypoperfusion is prevented.
[Zasshi] [Journal]. Nihon Kyōbu Geka Gakkai 05/1995; 43(4):473-8.
-
[show abstract]
[hide abstract]
ABSTRACT: This clinical study was undertaken to evaluate the Duran flexible ring and the Carpentier rigid ring in terms of mitral annulus motion, transmitral flow and left ventricular function. Twenty-six patients (11 receiving rigid rings and 15, flexible rings) with normal sinus rhythm and with no or only trivial mitral valve regurgitation after surgical repair were selected. Angiograms demonstrated no significant differences in left ventricular systolic function between the two groups of patients. The area of the mitral annulus with the flexible ring significantly changed during the cardiac cycle. There were significant differences in the left ventricular fractional shortening (rigid ring, 35.8%; flexible ring, 43.4%) and in the peak velocity (rigid ring, 222 cm/s; flexible ring, 186 cm/s) at peak exercise. These data suggest that the flexible ring interferes less with the normal movements of the mitral annulus during the cardiac cycle, and that, under exercise conditions, it performs better than the rigid ring. We therefore conclude that mitral valve reconstruction using the Duran flexible ring is advantageous in patients with mitral regurgitation due to degenerative disease and sinus rhythm.
The Annals of Thoracic Surgery 04/1995; 59(3):658-62; discussion 662-3. · 3.74 Impact Factor
