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Biomedical subjects

Y Shimazaki

Publications and source records attributed to Y Shimazaki.

At least 163 records · Page 9Linked to original sources
PubMed1990

Assessment of the intrapulmonary ventilation-perfusion distribution after the Fontan procedure for complex cardiac anomalies: relation to pulmonary hemodynamics.

In 12 patients who underwent the Fontan procedure for complex cardiac anomalies, lung scanning with xenon-133 was performed to assess the intrapulmonary ventilation-perfusion distribution, and comparison was made with a control group. All data were then analyzed in relation to either pre- or postoperative pulmonary hemodynamic data. In ventilation scans, the intrapulmonary distribution in the right lung was almost normal. In perfusion scans, an abnormal increased upper to lower lobe perfusion ratio greater than the normal value found in the control group was noted in seven patients (58.3%). There was a significant correlation (p less than 0.02) between the upper to lower lobe perfusion ratio and postoperative pulmonary vascular resistance. Furthermore, this perfusion ratio correlated inversely with the preoperative (p less than 0.005) and postoperative (p less than 0.02) right pulmonary artery area index, defined as the ratio of cross-sectional area to the normal value. Of five patients with less than 90% arterial oxygen saturation, four showed an abnormal distribution of pulmonary blood flow greater than the normal perfusion ratio. No patient had evidence of a pulmonary arteriovenous fistula by the echocardiographic contrast study. These results suggest that abnormal distribution of pulmonary blood flow to the upper lung segment may develop in patients after the Fontan procedure, and that insufficient size of the pulmonary artery before operation and the consequent postoperative elevation of pulmonary vascular resistance may be responsible for this perfusion abnormality.

Child↗
PubMed1990

Timing of operation for aortic regurgitation: relation to postoperative contractile state.

With angiography and pressure measurement, we determined left ventricular volume, wall stress, and systolic performance in 30 patients with aortic regurgitation before and after successful aortic valve replacement. End-systolic wall stress was greatly elevated preoperatively and decreased to normal postoperatively. Systolic pump performance assessed as ejection phase indexes was severely depressed preoperatively and improved to normal or near-normal postoperatively in most patients. The ratio of end-systolic wall stress to end-systolic volume index (ESS/ESVI), an index of myocardial contractility, was greatly decreased before operation. Postoperatively, the ratio increased in all patients, becoming normal in 12 of the 13 patients who had a preoperative ESS/ESVI of 2.9 or greater. However, 15 of 17 patients in whom the ESS/ESVI ratio was less than 2.9 still had subnormal ratios, which indicates the presence of irreversible contractile dysfunction. Stepwise multivariate analysis showed that preoperative ESS/ESVI was the only independent discriminator of postoperative normalization of the contractile function as assessed by ESS/ESVI. After aortic valve replacement, myocardial contractile state does not return to normal in a considerable number of patients. It is important to offer aortic valve replacement for aortic regurgitation before the chance for a good functional result is lost. The ESS/ESVI ratio may be a useful index in determining the timing of operation in patients with aortic regurgitation.

Adult↗
PubMed1990

[Measurement of endotoxin in blood products using an endotoxin-specific Limulus test reagent and its relation to pyrogenic activities in rabbit].

The amounts of endotoxin in commercial blood products were measured by the turbidimetric kinetic Limulus test with an ordinary reagent (LAL-HS) and a new endotoxin-specific reagent (LAL-ES). LAL-ES contains a sufficient amount of a water-soluble (1----3)-beta-D-glucan derivative as a blocker of the (1----3)-beta-D-glucan-mediated coagulation pathway in the reaction of the Limulus amebocyte lysate. The amounts of endotoxin in albumin and globulin products measured with LAL-ES agreed with pyrogenic activities in rabbits, but those measured with LAL-HS did not. Added endotoxin in the blood products was well recovered with LAL-ES, but that in some products was excessively recovered with LAL-HS. The amounts of endotoxin in diphtheria-pertussis-tetanus combined vaccines measured with LAL-HS and LAL-ES agreed with the pyrogenic activities in rabbits. The results suggested the existence of a false-positive substance like beta-glucan in the blood products but not in the vaccine. LAL-ES is more suitable for the detection of endotoxin in blood products than LAL-HS.

Animals↗
PubMed1990

[The influence of pulmonary regurgitation on left ventricular function after repair of tetralogy of Fallot].

The influence of right ventricular (RV) volume overload by pulmonary regurgitation (PR) on left ventricular (LV) function was evaluated postoperatively in 23 patients with tetralogy of Fallot (TF). The age at operation was 3.1 +/- 1.7 (mean +/- SD) years. The age at postoperative study was 5.9 +/- 2.0 years. We determined RV end-diastolic volume (%RVEDV), RV ejection fraction (EF), %LVEDV, LV end-systolic volume (%LVESV), LVEF, and LV end-systolic stress (ESS)/%LVESV. Patients were divided into 2 groups on the basis of presence or absence of RV volume overload by PR as follows: The %RVEDV (175 +/- 23%) of group 1 (n = 10) was 150% greater than normal RVEDV. Group 2 (n = 13) had normal %RVEDV (108 +/- 23%). Preoperatively, there had been no differences in hemoglobin, %RVEDV, RVEF, %LVEDV, LVEF, and in the ratio of average cross-sectional area of the left and right pulmonary arteries to cross-sectional area of the normal right pulmonary artery between the 2 groups. Moreover, there were no differences in age at repair, or during postoperative study, nor in the postoperative ratio of RV to LV systolic pressure between the 2 groups. RVEF was significantly less in group 1 than in group 2 (0.53 +/- 0.05 vs 0.58 +/- 0.05, p less than 0.05). %LVEDV and %LVESV in group 1, 138 +/- 10% and 171 +/- 30% respectively, were significantly greater than those in group 2, 116 +/- 11% and 133 +/- 20% respectively (p less than 0.001 in %LVEDV and p less than 0.01 in %LVESV).(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Volume↗
PubMed1990

[Relationship between postoperative atrial volumes and prognosis after modified Fontan operation in patients with complex cardiac anomalies].

We evaluated right and left atrial (RA and LA) volumes after modified Fontan operation in 6 patients, in 1 with mitral atresia and 5 with single ventricle. The age at operation was 10.2 +/- 2.5 (mean +/- SD) years. The interval between operation and study was 4.1 +/- 4.8 months. RA and LA maximum volume indexes (VImax) (ml/m2) were measured by angiography. One patient died 72 days after operation due to low output syndrome. In survived patients (n = 5), postoperative pulmonary arterial wedge pressure was 6 +/- 3 mmHg, right atrial pressure 13 +/- 5 mmHg, and end-diastolic pressure in the systemic ventricle 6 +/- 3 mmHg, and one who died had 18 mmHg, 25 mmHg, and 9 mmHg in each parameter, respectively. LAVImax in the survivors (53 +/- 18 ml/m2) were in the range of normal or above normal value. The nonsurvivor had extremely small LAVImax (13 ml/m2). RAVImax in the alive patients (25 +/- 11 ml/m2) was smaller than normal (data was not available in a non-survived patient). These results may indicate that a normal LA volume appears to be as important factor for the prognosis after modified Fontan operations with intraatrial routing for complex lesions regardless of the postoperative RA volume.

Adolescent↗
PubMed1990

Pulmonary artery pressure and resistance late after repair of tetralogy of Fallot with pulmonary atresia.

Twenty-one patients underwent elective hemodynamic and cineangiographic studies 1 to 9 years after repair of tetralogy of Fallot and pulmonary atresia. They were a subset of 41 patients who underwent complete repair between Jan. 1, 1973, and 1988. The mean and systolic pulmonary arterial pressure, as well as the pulmonary vasculature resistance, were abnormally high in 60% of the patients. Thirty-three percent of the patients were found to have pulmonary arterial segments that were not connected to the central and unbranched hilar portions of the right and left pulmonary arteries. The mean pulmonary artery pressure and the pulmonary vasculature resistance were correlated (inversely) with the number of centrally connected pulmonary arterial segments. The pulmonary vasculature resistance per pulmonary arterial segment was also inversely correlated with the number of centrally connected pulmonary arterial segments. Inferences: The finding that abnormalities in the pulmonary vasculature of centrally connected pulmonary arterial segments become more severe as the number of centrally connected pulmonary arterial segments decreased has implications as to hemodynamic effectiveness of unifocalization operations. Since others have found these abnormalities in the pulmonary vasculature to be age related, the findings support beginning the appropriate surgical treatment of patients with tetralogy of Fallot and pulmonary atresia very early in life.

Adolescent↗
PubMed1989

Right ventricular myocardial function after atrial switch operation for transposition of the great arteries.

Postoperative right ventricular (RV) myocardial function was evaluated in 6 patients who underwent atrial switching for simple transposition of the great arteries (TGA). The average age at study was 5.5 years. RV function was evaluated at rest and during administration of methoxamine by cardiac catheterization and RV angiography. The data were compared with left ventricular function in a control group, which consisted of 6 patients, 3 with functional murmur and 3 with pulmonary valvar stenosis. During stress, the TGA group showed a significant increase in end-diastolic pressure, minute work index and end-diastolic and end-systolic volume indexes, along with a significant decrease in ejection fraction. The control group also showed an increase in these variables except for ejection fraction during stress, which did not change. The slope of the work-function curve for the TGA group was lower than that for the control group (p = 0.02). The TGA group had a lower slope of the peak systolic pressure-volume relation than the control group (p = 0.005). There was no significant correlation between the slope of the peak systolic pressure-volume relation and age at repair or study. This study shows that RV pump dysfunction observed in postoperative TGA patients may be caused by depressed myocardial function.

Cardiac Catheterization↗
PubMed1989

Autopsy findings 14 years after septation for single ventricle.

The autopsy findings of a patient who survived 14 years after ventricular septation for single ventricle are reported. Although the patient had been well for years, she suddenly died at 22 years of age. Her ventricular free walls had grown normally, but the ventricular septum did not. A crevice was found in the apex, and the ventricular septum consisted of only the Teflon patch. Microscopically, fibrosis was found only in the right atrium.

Adult↗
PubMed1989

Effects of extracellular calcium and sodium on cadmium uptake in guinea-pig and rabbit aorta.

1. Effects of Na+ and Ca2+ on Cd2+ uptake in the guinea-pig and rabbit aorta were investigated. 2. The Cd2+ fraction can be divided with EDTA and Zn2+. The EDTA fraction may be intracellular fraction and the Zn2+ fraction may be loosely bound to surface membrane. 3. In Na+ deficient solution the Zn2+ fraction was markedly increased and the EDTA fraction also increased while the external Ca2+ concentrations scarcely affect the Cd2+ contents in both fractions. 4. Cd2+ did not affect the cellular Na+ and K+ contents. 5. These results suggest that Na+ strongly relates with these fractions but Na+ pump does not contribute to these phenomena.

Animals↗
PubMed1989

Assessment of ventricular contractile state and function in patients with univentricular heart.

To elucidate the ventricular contractile state and function in patients with univentricular heart, the ventricular volume, mass, ejection phase index, and wall stress were evaluated with biplane ventriculography and pressure measurement in 41 patients: 18 with left ventricular (LV) type (age, 6.4 +/- 6.1 years) and 23 with right ventricular (RV) type (age, 5.7 +/- 4.1 years), and data from patients with univentricular heart were compared with data from 19 normal control subjects (age, 7.2 +/- 4.3 years). Although the end-diastolic and end-systolic volumes were significantly greater in both types of univentricular heart than in the normal control group, the volumes for the LV and RV type patients did not differ from each other. The ejection fraction (EF) was depressed in both patient types of univentricular heart and was significantly (p less than 0.005) lower in the RV type than in the LV type patients (0.56 +/- 0.05 for LV type, 0.50 +/- 0.07 for RV type, and 0.64 +/- 0.03 for the control group). The ventricular mass was larger in both patient types of univentricular heart than in that of the control group, whereas the ratio of ventricular mass to end-diastolic volume was significantly (p less than 0.001) lower in the RV type patients than in the LV type patients and the control group (0.79 +/- 0.18 g/ml for LV type, 0.51 +/- 0.10 for RV type, and 0.82 +/- 0.13 for control group). End-systolic stress was significantly elevated in both types of univentricular heart (241 +/- 45 for LV type, 328 +/- 52 for RV type, and 205 +/- 26 kdynes/cm2 for the control group) and significantly (p less than 0.001) greater in the RV type than in the LV type patients. There was a significant inverse correlation (p less than 0.001) between end-systolic stress and the ratio of mass to end-diastolic volume in all the patients. In 27 patients (12 patients for LV type, 15 for RV type) the mean normalized systolic ejection rate corrected for heart rate (MNSERc) clearly fell below the 95% confidence limit of the normal end-systolic stress-MNSERc relation. The end-systolic stress:end-systolic volume ratio was also significantly depressed in both patient types of univentricular heart (3.49 +/- 1.77 for LV type, 4.07 +/- 2.13 for RV type, and 7.20 +/- 1.32 for the control group). In these variables, however, there were no significant differences between LV and RV type patients of univentricular heart.(ABSTRACT TRUNCATED AT 400 WORDS)

Angiocardiography↗
PubMed1989

[Left ventricular volume characteristics and its relationship with right ventricle after repair of tetralogy of Fallot].

In order to study the left ventricular volume characteristics and right ventricular influence on left ventricle, cardiac catheterization and biplane cineangiography was performed in 61 patients after repair of tetralogy of Fallot. Preoperative left ventricular volume size was also measured in 25 patients. Postoperative left ventricular end-diastolic volume index (LVEDVI) was 93 +/- 22 ml/m2 (mean +/- standard deviation) and it was 140 +/- 29% of normal left ventricular volume. Left ventricular ejection fraction (LVEF) was 60 +/- 6%. Left ventricular size significantly increased from 109 +/- 25% to 140 +/- 23% of normal by corrective surgery (p less than 0.001). Left ventricular volume characteristics are correlated with right ventricle. LVEDVI increased with increasing right ventricular end-diastolic volume index (RVEDVI) and decreased right ventricular ejection fraction (RVEF). LVEDVI (ml/m2) = 60 + 0.29 RVEDVI (ml/m2), r = 0.52, p less than 0.001, LVEDVI (ml/m2) = 141 - 0.90 RVEF (%), r = -0.30, p less than 0.02. LVEF decreased with increasing RVEDVI and decreased RVEF. LVEF (%) = 68 - 0.075 RVEDVI (ml/m2), r = -0.51, p less than 0.001, LVEF (%) = 43 + 0.32 RVEF (%), r = 0.40, p less than 0.001. On the contrary there was no relationship between right ventricular volume characteristics and right ventricular systolic pressure. There were two cases whose LVEF was less than 50%. In one case right ventricular systolic pressure was as high as 98 mmHg. In the other patient RVEDVI was 299 ml/m2 (453% of normal right ventricular volume) because of severe pulmonary regurgitation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

[Extended aortic arch anastomosis for aortic coarctation in neonate and early infancy--experience in 5 patients].

The aortic coarctation (CoA) was repaired with extended aortic arch (AA) anastomosis in 5 consecutive patients, 2 in neonate and 3 in infancy, ranging in age from 3 to 106 days. The associated lesions were ventricular septal defect in 2, atrial septal defect in 2 and complete atrioventricular canal in 1. Patent ductus was found in 4 and prostaglandin E1 was required in 2 with response in 1 patient. The AA was hypoplastic in 2 patients with arch to descending aorta diameter ratio below 0.5. The CoA repair was performed as the first procedure in all. The primary anastomosis was possible in all between AA and the descending aorta without undue tension after removal of the all ductus tissue and extensive mobilization of the aorta. Aortic clamp time was 28 minutes in average. The intraoperative pressure gradient after repair across AA was 0 to 10 mmHg (average 4.6 mmHg). All except 1 with preceding hepatic dysfunction tolerated the procedure without complication or operative death. Postoperative evaluation at 1 to 11 months showed no significant pressure gradient between upper and lower extremities. This method appears to be useful for CoA in early infancy particularly when AA is hypoplastic.

Anastomosis, Surgical↗
PubMed1989

Depressed myocardial contractility and normal ejection performance after aortic valve replacement in patients with aortic regurgitation.

Left ventricular cineangiography and pressure measurement were performed in 33 patients with chronic aortic regurgitation before and after aortic valve replacement and in 25 normal control subjects. Stress and volume were analyzed. The 33 patients were divided into three groups based on preoperative end-systolic volume index: 15 with an index of less than 100 ml/m2 (group I), 12 with an index of 100 to 200 ml/m2 (group II), and six with an index of more than 200 ml/m2 (group III). Afterload estimated as end-systolic stress, which was significantly elevated in all groups before operation, returned to normal postoperatively. Systolic pump function improved postoperatively in all groups; group I and group II showing the most improvement with group III still having an abnormal ejection fraction. The ratio of end-systolic stress to end-systolic volume index, which is an index of contractile state that is relatively independent of preload and afterload, was abnormal in each group preoperatively. Postoperatively, the ratio improved in each group (from 2.8 +/- 0.5 to 4.8 +/- 0.9 for group I, from 1.4 +/- 0.3 to 3.2 +/- 0.6 for group II, and from 0.8 +/- 0.2 to 2.6 +/- 0.8 for group III, compared with 5.9 +/- 1.0 for control subjects). Group I had normal values whereas group II and group III had subnormal ratios, suggesting a depressed contractility. All 15 patients in group I had values that fell within the 95% confidence limits of the linear inverse relationship between ejection fraction and end-systolic stress for control subjects. Nine of the 12 patients in group II and all six in group III had values that fell below the 95% confidence limits of the normal ejection fraction-end-systolic stress relationship. Aortic valve replacement may reduce afterload and improve systolic pump function in many patients with aortic regurgitation. However, there is a subgroup of patients who, despite normal or near-normal pump performance as assessed by ejection fraction, have depressed myocardial contractility characterized by an abnormal relationship between end-systolic stress and either ejection fraction or end-systolic volume.

Adolescent↗
PubMed1989

[Noninvasive and quantitative evaluation of pulmonary regurgitation by pulsed Doppler echocardiography--a study in patients with tetralogy of Fallot after corrective surgery].

A noninvasive and quantitative evaluation of pulmonary regurgitation (PR) using pulsed Doppler echocardiography (PDE) was performed in 25 patients with tetralogy of Fallot (TOF) after corrective surgery. Considering a possibility of the presence of the difference in regurgitant flow velocity in pulmonary artery, four sampling points for detecting the pulmonary regurgitant flow were designed as follows: point 0 was positioned at the right ventricular outflow tract; point 1, at the pulmonary annulus; point 2, at mid-portion of the pulmonary trunk; point 3, at bifurcation of the pulmonary artery. The values of maximum Doppler shift determined by analysing the sonograms recorded at point 1, 2 and 3 were examined in comparison with the grades of PR estimated by pulmonary arteriography and the results obtained were as follows. In a retrospective study in 18 patients with PR, the values of maximum Doppler shift were highest at point 1, and followed by point 2 and point 3 in order (p less than 0.005), indicating that the velocity gradient of regurgitant flow existed in the pulmonary artery. The values of maximum Doppler shift were highest in the group of PR grade III estimated by pulmonary arteriography, and followed by the group of PR grade II and grade I in order. At point 2, the group of grade III-PR showed significantly higher Doppler shift than the group of grade I-PR (p less than 0.05). Following above data, a new criteria for estimating the severity of PR by PDE according to the velocity gradient of regurgitant flow in the pulmonary artery was proposed. In a prospective study in a separate group of other 7 patients, the grade of PR estimated by PDE corresponded well with these of pulmonary arteriography, with a significant Spearman rank correlation coefficient (rs = 0.90, p less than 0.01). An experimental study using a dog with surgically induced PR of different grades confirmed the presence of higher Doppler shift in pulmonary artery corresponding to the grade of PR. These results indicated the usefulness of a newly proposed method evaluating PR by PDE applying a concept of Windkessel model for PR regurgitant flow.

Adolescent↗
PubMed1989

[Arterial switch operation for simple transposition of the great arteries in infancy].

Five infants (22-42 days of life) underwent arterial switch operation for simple transposition of the great arteries under deep hypothermic cardio-pulmonary bypass. Three babies required prostaglandin E1 infusion to keep ductus arteriosus opened widely before surgery. Balloon atrioseptostomy was necessary in 0-10 days of life in all babies because of poor condition. Left to right ventricular peak pressure ratio ranged from 0.75 to 0.86, preoperatively. Four of the five survived the operation, and one died of coronary insufficiency because of kinking of the implanted coronary artery. Hypothermic circulatory arrest was used in three (38-41 minutes). Aortic cross clamp time was 70-100 minutes, and cold crystalloid cardioplegia was given only one time just after aortic clamp in 3 babies. Single dose of cardioplegia protected left ventricular muscle well in babies with transposition of the great arteries as same as multiple dose method used in those with ventricular septal defect.

Humans↗
PubMed1989

Comparison of single dose versus multiple dose crystalloid cardioplegia in neonate. Experimental study with neonatal rabbits from birth to 2 days of age.

Thirty-five isolated hearts from newborn rabbits (aged birth to 2 days) were subjected to 120 minutes of ischemia at 15 degrees C with high potassium crystalloid cardioplegia. They were divided into four groups according to the method of cardioplegic administration: group C (preischemic control, n = 9), group S (single dose, n = 10), group M-1 (multiple dose, infused every 40 minutes, n = 7), and group M-2 (multiple dose, infused every 20 minutes, n = 9). After 30 minutes of reperfusion, the heart rate, coronary flow, creatine kinase release, percent water content, and myocardial ultrastructural scores for mitochondrial damage and intracellular edema were compared among the four groups. All of these parameters except coronary flow were significantly poorer in group M-2 than in groups C and S (p less than 0.05). The mitochondrial damage and intracellular edema scores were significantly poorer in group M-1 than in group C (p less than 0.05). No significant differences in these two scores were seen between group S and group C and between group S and group M-1. These results indicate that the single dose method of administering crystalloid cardioplegia may provide better myocardial protection than the multiple dose method in the neonate.

Animals↗
PubMed1989

[Evaluation of total cavopulmonary shunt operation from late results].

Total cavopulmonary shunt was performed in 6 patients (pts) with single ventricle and common atrioventricular valve (CAVV) with left isomerism between 1978 and 1987. Four patients survived including 1 with CAVV-replacement and follow-up period ranged from 1.5 to 10 years. The first pt tolerated a pregnancy and re-replacement of CAVV. All 4 pts showed significant improvements in symptom. The arterial oxygen saturation was around 90% early postoperatively, but 2 pts developed pulmonary arteriovenous fistula with decreased arterial oxygen saturation. This operation can be indicated in left isomerism with low operative risk, and also may be applied in those with CAVV regurgitation although the risk becomes high. PAVF is a matter of concern in the late follow-up.

Adult↗