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Biomedical subjects

M Shigenobu

Publications and source records attributed to M Shigenobu.

At least 19 recordsLinked to original sources
PubMed1995

Detection of "pathologic" prosthetic valve stenosis via exercise Doppler echocardiography.

To detect borderline mitral valve dysfunction in asymptomatic patients, with Björk-Shiley valves, we studied the patients' hemodynamics at rest and during exercise by Doppler echocardiography. Supine bicycle exercise was performed by 65 patients. The patients were divided into two groups according to the measurements of the exercise Doppler echocardiography: a normally functioning group (n = 45) and a borderline group (n = 20). The valve area at rest was 2.0 +/- 0.6, 2.1 +/- 0.7, and 2.3 +/- 0.5 cm2 with valve sizes of 25, 27, and 29 mm, respectively, in the normal group and 1.9 +/- 0.5, 1.9 +/- 0.4, and 2.1 +/- 0.3 cm2 in the borderline group. The mitral valve area did not significantly change with exercise in either group. In the normal group, peak gradients increased from 9.9 +/- 3.5, 9.7 +/- 1.1, and 9.5 +/- 1.6 mmHg with valve sizes of 25, 27, and 29 mm, respectively, at rest to 15.1 +/- 3.1, 14.0 +/- 3.3, and 14.8 +/- 2.6 mmHg with exercise. Mean gradients increased from 5.2 +/- 1.2, 5.9 +/- 1.3, and 5.8 +/- 1.8 mmHg with valve sizes of 25, 27, and 29 mm, respectively, at rest to 8.0 +/- 2.5, 9.1 +/- 2.0, and 8.8 +/- 1.6 mmHg with exercise. In the borderline group, peak gradients increased from 10.5 +/- 3.1, 10.1 +/- 2.1, and 10.8 +/- 1.7 mmHg with valve sizes of 25, 27, and 29 mm, respectively, at rest to 24.5 +/- 4.2, 23.6 +/- 4.4, and 22.4 +/- 3.2 mmHg with exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Echocardiography, Doppler↗
PubMed1995

Evaluation of St. Jude Medical mitral valve function by exercise Doppler echocardiography.

The aim of this study was to detect borderline mitral valve dysfunction in 100 asymptomatic patients with a St. Jude Medical valve. We studied rest and exercise hemodynamics by Doppler echocardiography. Study patients were divided into two groups according to the time since surgery: group A had valves implanted less than 5 years ago (44 patients), group B had valves implanted more than 5 years ago (56 patients). Although patients had no clinical signs of valve dysfunction, group B was found to have significant reduction of mitral valve area (p < 0.05). In the group A patients, mean gradients at rest increased from 4 +/- 2, 4 +/- 2, and 3 +/- 1 mmHg in valve sizes of 25, 27, and 29 mm, respectively, to 7 +/- 2, 7 +/- 3, and 5 +/- 2 mmHg with exercise. In the group B patients, mean gradients at rest increased from 7 +/- 1, 6 +/- 2, and 5 +/- 1 mmHg to 14 +/- 3, 13 +/- 3, and 10 +/- 4 mmHg, respectively, after exercise. The percent increase (mean) in peak pressure gradient with exercise was significantly higher in group B (more than 100%) than in group A (less than 80%) (p < 0.01). The percent increase in mean gradient with exercise was also significantly higher in group B (more than 100%) than in group A (less than 75%). In conclusion, patients with reduced valve area and more than a 100% increase of peak and mean gradients should be followed up carefully. If any signs or symptoms of heart failure develop, they must be considered as candidates for surgery.

Adult↗
PubMed1994

The clinical and pathological features of isolated aortic regurgitation in relation to its etiology.

Chronic isolated aortic regurgitation (AR) caused by degenerative, rheumatic, and Marfan etiologies were compared in a study of 87 patients. There were three hospital deaths in the Marfan group, but none in the rheumatic and degenerative groups. The late postoperative survival rates at 5 and 10 years were 98% and 94%, respectively, in the rheumatic group; 84% and 84%, respectively, in the degenerative group; and 85% and 78%, respectively, in the Marfan group. An analysis of the late complications disclosed a higher incidence of aortic dissection and paravalvular leakage in the degenerative and Marfan groups than in the rheumatic group. In the degenerative group, 4 of the 32 patients developed acute aortic dissection within 3 years following aortic valve replacement. The aortic root diameter in these 4 patients was more than 40 mm at the time of surgery, whereas it was less than 40 mm in the remaining 28 patients. In conclusion, considering the progressive nature of myxomatous degeneration, patients with a severely dilated aortic root diameter should be monitored carefully with echocardiography after surgery.

Adult↗
PubMed1994

The effect of myocardial preservation technique on supraventricular tachycardia following aortic valve replacement.

We studied 100 patients who underwent an isolated aortic valve replacement (AVR) between 1974 and 1991. The patients were divided into the following two groups and compared: group A, which consisted of 40 patients operated on before 1978 who underwent continuous left coronary perfusion with blood; and group B, which consisted of 60 patients operated on after 1979 in whom St. Thomas solution was used in combination with topical cardiac cooling. Moreover, we divided the group B patients into two subgroups: group B1, who underwent AVR before 1986 during which we administered St. Thomas solution with ice slush every 30 min; and group B2, who had AVR after 1986 in which we used St. Thomas solution with a cold saline (4 degrees C) solution and treated with a small amount of slushed ice very 15 min. The incidence of supraventricular tachycardias was 15% in group A, 50% in group B1, and 15% in group B2. The severity of preoperative New York Heart Association (NYHA) functional class, the type of valve lesions, cardiothoracic ratio, left ventricular function, aortic clamp time, bypass time, and use of drugs did not correlate with the incidence of supraventricular tachycardias in either group A or B. In group B2 patients, we paid a lot of attention to cooling the right atrium as well as the left ventricle by immersing the whole heart using a 4 degrees C saline solution, which led to a remarkable reduction of the incidence of supraventricular tachycardia. This fact indicates that right atrial preservation is one of the most important factors for reducing the incidence of supraventricular tachycardia.

Aortic Valve↗
PubMed1994

Surgical indications and treatment of mitral valve disease associated with secundum atrial septal defect with special reference to left ventricular geometry and function.

There are few reports that discussed surgical indications and selection of surgical procedures for secundum atrial septal defect (ASD) associated with mitral valve disease from the viewpoint of left ventricular geometry and function. Our study on 20 patients (6 patients with ASD and MS, 14 patients with ASD and MR) indicated that adult patients with ASD and MS can be treated surgically even when left ventricular end-diastolic volume index (LVEDVI) is as low as 35 ml/m2 (one third of the normal level). Left ventricular wall movement returned to normal one year following surgery. Therefore, rather than myocardial impairment, right ventricular volume load disturbing left ventricular dilatation would be the more likely cause of diminished left ventricular function before surgery in the ASD and MS group. In both groups, two patients who initially had undergone mitral valve replacement died from low output syndrome because of the mismatch between the left ventricular volume and the prosthesis used, whereas there were no deaths in the patients who had mitral valve repair. For this reason, mitral valve repair is the treatment of choice for patients with both secundum ASD and mitral valve disease. When valve replacement is the only alternative, selection of prosthetic valves and maintenance of cardiac output by temporary cardiac pacing are important considerations. A low profile valve with a larger orifice area should be selected to avoid the mismatch between a left ventricular volume and a prosthesis.

Adult↗
PubMed1994

Criteria to detect mitral prosthetic valve dysfunction via continuous wave Doppler echocardiography.

To detect the diagnostic criteria for mitral prosthetic valve dysfunction, Doppler echocardiography was used to assess valve function following mitral valve replacement in 100 patients [50 with St. Jude Medical (SJM) valves, 50 with Björk-Shiley (B-S) valves]. Mitral valve area (MVA) was calculated by dividing a constant of 220 by pressure half time (PHT) measured via Doppler technique [220/PHT]. The relationship of MVA to left ventricular function, geometric valve area (GVA) of the prosthetic valve, body surface area (BSA), and maximum disc-opening angle (maxOA) were assessed. In the SJM valves, MVA significantly correlated with valve area index (GVA/BSA). The % area index [(MVA/valve area index) x 100] was 100.2 +/- 12.8% on the average and no patients with the SJM valve showed the %area index of less than 73%. There was no incidence of valve dysfunction in the SJM valves. We concluded from these results that if the % area index is less than 73% (mean -2SD), the SJM valve dysfunction should be diagnosed. When the B-S valves were examined, there were 19 patients in whom the maximum opening angle had decreased to under 58 degrees. These patients also had decreased MVA and % area index. Evaluation of the relationship between the maximum opening angle and the % area index revealed that the patients in whom the maximum opening angle had diminished to under 50 degrees had low % area index (of less than 70%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Criteria to select proper valve prosthesis for aortic valve replacement. Comparative assessment of various valve prostheses via continuous wave Doppler echocardiography.

Continuous wave Doppler echocardiography was used to measure pressure gradients (PG) across various aortic valve prostheses [St. Jude Medical (SJM) valve: 55 cases; Björk-Shiley (B-S) valve: 18 cases; Lillehei-Kaster (L-K) valve: 25 cases; and Omniscience (O-S) valve: 49 cases]. Disc-opening angles of the L-K and O-S valves were measured via cineradiography. Pressure gradient across the SJM valve tended to be low. Increase in pressure gradients during exercise tended to be greater in the small valves. There was a significant correlation between the valve area index (VAI) and pressure gradients in the SJM valve (PG = 85.3-40.2 x VAI, r = -0.71, p < 0.005) and in the B-S valve (PG = 64.6-23.3 x VAI, r = -0.89, p < 0.025). To keep pressure gradients below 20 mmHg, SJM valve #23 and B-S valve #25 should be selected for patients with a body surface area of 1.3-1.7 m2. In the L-K and O-S valves, there was no significant correlation between VAI and PG, likely because the disc-opening angles of these valves were suboptimal--averaging 57 degrees in the L-K valve and 47 degrees in the O-S valve. None of the patients with SJM or B-S valves had pressure gradients of 50 mmHg or above. However, pressure gradients exceeded 50 mmHg in 7 cases with the L-K valve (28%) and 10 with the O-S valve (20%), suggesting the necessity of careful follow-up in patients with these prostheses.

Aortic Valve↗
PubMed1993

[Urgent mitral valve replacement for acute mitral regurgitation due to ruptured chordae tendineae in systemic lupus erythematousus].

We reported a successful surgical treatment of mitral regurgitation (MR) due to ruptured chordae tendineae in a 44-year-old man with systemic lupus erythematosus (SLE) who had received the steroid therapy. He had signs of acute congestive heart failure with severe pulmonary hypertension due to MR, and underwent urgent mitral valve replacement. The postoperative course was uneventful. When replacing valve in SLE, a careful manipulation should be taken because of friability of cardiovascular tissue. Patients are usually administered steroid agents, and the agents ought to be discontinued in perioperative period, but it seems to be better to resume as soon as possible. We conclude that the surgical treatment for valvular diseases should be considered, even in the patient with SLE.

Acute Disease↗
PubMed1993

A case of cor triatriatum with end-stage renal disease: successful management of open heart surgery under hemodialysis, subsequent renal transplantation and pregnancy.

A female patient who had open heart surgery for cor triatriatum under hemodialysis, subsequent kidney transplantation and pregnancy is reported. We performed hemodialysis on the patient before, during and after heart surgery to control renal failure. Two years after heart surgery, she received a kidney graft from her mother. The kidney graft showed good function. She was treated with azathioprine and prednisone. Three years after renal transplantation she delivered a healthy male infant by elective Caesarean section at 37 weeks' gestation. Mother and infant did well following delivery. There was lack of hypertension, proteinuria, signs of graft rejection, and recurrence of heart failure during pregnancy. She showed serum creatinine level < 2 mg/dl, a prednisone of < 2 mg/kg/day. Elective Caesarean section has improved hydronephrosis due to the compression of the fetus. The aforementioned good criteria contributed to the successful pregnancy of the renal transplant patient in our experience. We believe early surgical intervention overcomes complicated heart disease even with endstage renal disease, and it gives a chance to receive renal transplantation and have a healthy child. To our knowledge, this is the first report that has described the successful management of open heart surgery under hemodialysis, subsequent renal transplantation and pregnancy in a female patient with chronic renal failure.

Adult↗
PubMed1992

Indications and timing of surgery for cholelithiasis associated with valvular heart disease.

Twenty patients with cholelithiasis associated with valvular heart disease were studied to assess the need and the optimal time for cholecystectomy. Twelve patients (11 symptomatic and 1 asymptomatic patients) underwent cholecystectomy. The remaining patients were asymptomatic. The levels of the total bilirubin in 9 patients, and of LDH in 15, were higher than normal. In most of the patients, the serum transaminase levels were higher than normal, but in few cases, the levels were higher than 200 IU/l. These abnormal values, however, were not consistently observed in these patients. No clear association between the type and form of valvular heart disease was demonstrated. The type of prostheses used for valve replacement in these patients were ball, tilting disc and leaflet. No significant differences in efficacy were observed among different types of prostheses. The incidence of silent stones is high in patients with valvular heart disease and heart surgery often causes deterioration in patients with cholelithiasis. The recovery of the patients who underwent cholecystectomy before valve replacement were better than those who underwent cholecystectomy after heart surgery. In conclusion, therefore, patients showing any abnormal results in liver function tests should be assessed in detail by abdominal echography and should receive surgical treatment of biliary tract before heart surgery if necessary.

Cholelithiasis↗
PubMed1992

Long-term results of surgery for mitral regurgitation due to mitral valve prolapse: a comparison of valve replacement and annuloplasty.

Patients with mitral regurgitation (MR) due to mitral valve prolapse operated at the Second Department of Surgery, Okayama University Medical School, between 1976 and 1986 were divided into two groups. The first consisted of 20 patients who had mitral valve replacement (MVR) and the second 15 patients who had mitral annuloplasty (MAP). Long-term results of surgery, cardiac function, hemodynamic status, and surgical findings were compared between the two groups. Before surgery, there were no significant differences in patient's clinical status and cardiac function between the two groups. However, after surgery statistically significant differences emerged between the two groups in ejection fraction (EF), cardiac index (CI) and mean circumferential fiber shortening velocity (mVcf). Left ventricular pumping function and myocardial contractile force tended to decrease after surgery in the MVR group and to remain unchanged or even increase in the MAP group indicating that valve preservation procedures should be selected as often as possible for the patients involved in mitral valve prolapse.

Adolescent↗
PubMed1992

Factors influencing the efficacy of DeVega's annuloplasty for secondary tricuspid regurgitation.

DeVega's annuloplasty was performed on 41 patients with tricuspid regurgitation (TR) associated with combined valvular disease and results were assessed based on Doppler echocardiographic findings in an attempt to examine the applicability of this surgical technique. TR was quantitatively evaluated via Doppler echocardiography before and after surgery. Clinical symptoms, cardiac function, and surgical results were assessed, and the severity of left ventricular myocardial degeneration was determined using electron microscopy. There were no differences in the following factors between the TR recurrence and TR improvement groups: previous heart surgery, number of involved valves, presence or absence of a giant left atrium, preoperative New York Heart Association (NYHA) functional class, and type of prosthetic valve (Björk-Shiley vs. St. Jude Medical). We found no differences between these two groups in TR severity and tricuspid annulus diameter measured during surgery. Severity of myocardial degeneration was closely associated with the recurrence of TR. Clinically, most had diminished cardiac function before surgery. DeVega's technique appears to be remarkably effective in patients with well-preserved myocardium because no TR recurrence was detected even in examinations with the most accurate Doppler echocardiography. However, such long-term effectiveness of DeVega's technique cannot be expected in patients with degenerated myocardium.

Adult↗
PubMed1992

Effect of left atrial plication for the giant left atrium on left ventricular function.

Left atrial plication (LAP) following Kawazoe's method was performed on eight patients with mitral valve stenosis associated with a giant left atrium. To investigate the effect of LAP particularly on left ventricular function, the preoperative and postoperative left ventricular function in these patients were compared. The data were also compared to that of the non-left atrial plication (non-LAP) group with left atrial dimension of 60 mm or over. In the LAP group, there were significant differences between preoperative and postoperative data in the following parameters; New York Heart Association (NYHA) class, cardiothoracic ratio, mean pulmonary arterial pressure (PAP), left ventricular end-diastolic pressure (LVEDP), left atrial dimension, stroke volume index, ejection fraction and cardiac index. On the contrary, in the non-LAP group, there were significant differences between preoperative and post-operative data in the following two factors; NYHA class and PAP. The size of the left atrium in the non-LAP group remained unchanged over the course of long-term follow-up. Despite severe clinical symptoms and severely reduced cardiac function of the patients in the LAP group, cardiac function in all patients improved satisfactorily. This suggests that left atrial plication has a considerably beneficial effect on left ventricular function, and therefore, may be recommended for patients with a giant left atrium.

Adult↗
PubMed1991

Doppler echocardiographic evaluation of Björk-Shiley and St. Jude Medical prostheses in the mitral position.

The left ventricular studies by Doppler echocardiography were performed in 50 patients with a Björk-Shiley (B-S) mitral valve and 50 patients after implantation of a St. Jude Medical (SJM) mitral valve; the effect of valve replacement on the hemodynamic performance at rest and during bicycle exercise was determined from serial echocardiographic data. Twenty-eight patients (56%) of the B-S group and 42 patients (84%) of the SJM group showed a good response to the exercise. There was no significant difference in the effective orifice area at rest among each sizes of the B-S valve. In the SJM valve, on the contrary, the effective valve orifice area increases in parallel to the size of the SJM valve. There was a clear relation between the valve size and pressure gradient. The pressure gradient directly depends on the valve size and the effective orifice area in the SJM valve. High pressure gradient group in both prostheses had a tendency to take negative values of percent increase in stroke volume. Further, there were no cases showing positive values of percent increase in end-diastolic volume among the patients whose pressure gradients were assumed to be more than 10 mmHg at rest. It is suggested that impairment of inflow caused by the artificial valve, prosthetic valve stenosis, is possibly a significant factor causing left ventricular dysfunction, notably a decrease in stroke volume during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Comparison of noninvasive techniques in evaluation of the Björk-Shiley and the St. Jude Medical valve prostheses in mitral position].

Pressure gradients and left ventricular function were assessed by Doppler echocardiography in 50 patients with Björk-Shiley mitral valve and 50 patients with St. Jude Medical valve prosthesis. There was correlation between pressure gradient and valve size, and between effective valve orifice area and valve size for St. Jude Medical valve. These correlations were not found in Björk-Shiley valve. Clinical improvement and cardiac function were quite satisfactory in 20 patients with Björk-Shiley valve and in 32 patients with St. Jude Medical valve whose pressure gradients were less than 10 mmHg. Twenty eight of 50 patients with Björk-Shiley valve and 42 of 50 patients with St. Jude Medical valve showed good response to the exercise test. Eight patients underwent reoperation because of unacceptably high gradient caused by thrombus and pannus formation. The patients who show high pressure gradient across the valve prosthesis should be followed up cautiously.

Cardiac Volume↗
PubMed1990

[Elective prosthetic valve reoperation to relieve unacceptably high gradient].

Pressure gradients of Lillehei-Kaster valve (13 patients), Omniscience valve (26 patients) and Omnicarbon valve (7 patients) in the aortic position were evaluated by Doppler echocardiography. Twenty-three out of 46 patients revealed unacceptably high gradients. Seven prostheses were removed because the valve design that they had high gradients across them. Clinical findings including left ventricular function and symptoms improved after the reoperation. Patients who underwent aortic valve replacement with this series of valve prostheses should be followed up cautiously.

Aortic Valve↗
PubMed1989

Return to work after heart valve replacement.

One hundred patients who underwent heart valve replacement during the years 1977 to 1985 were reviewed an average of 57 months after surgery. The overall rate of reemployment after the operation was 78%. The most important factors influencing the return to work were the employment status before surgery, age at the time of surgery, the number and site of the diseased valve, the preoperative New York Heart Association (NYHA) functional class and the number of times cardiac surgery was performed. These factors were closely related to the optimal timing of heart valve replacement. It was suggested that the rate of return to work and the quality of life would be improved if the heart valve replacement had been performed at an earlier stage of the disease.

Adolescent↗