Biomedical subjects

F Okamoto

Publications and source records attributed to F Okamoto.

At least 73 records · Page 4Linked to original sources

PubMed1992

[Cardiac strangulation with permanent epicardial pacemaker lead].

A 3-year-old boy underwent corrective surgery for tetralogy of Fallot. During the operation, permanent epicardial pacemaker leads were implanted for complete A-V block, which was transient and a generator implantation was not necessary. The postoperative course was uneventful and he had been doing well until nine years of age, when he was admitted to our hospital with general fatigue. The data of echo cardiogram and cardiac catheterization showed the biventricular heart failure with right ventricular outflow tract obstruction (RVOTO). Because of his rapid deterioration refractory to the intensive medical therapy, semi-emergency surgery was recommended to relieve his RVOTO. It was found during the operation that the looped pacemaker leads had carved deeply in the atrioventricular groove, so that compressed the main pulmonary artery, left main coronary artery and encircled left ventricle. The pacemaker leads were dissected as long as possible, and cut segmentally. Additionally a patch enlargement of the main pulmonary artery was necessary to relieve the residual stenosis. Although IABP support was needed in a while, his postoperative course was uneventful, and postoperative examinations showed normal cardiac function. This rare complication, so called "cardiac strangulation", should be in mind when the implantation of permanent pacemaker leads is indicated in pediatric cases.

Child↗

PubMed1991

[A case of an aberrant subclavian artery-esophageal fistula due to prolonged nasogastric intubation].

A case of fatal hematemesis due to an aberrant right subclavian artery-esophageal fistula is presented. The patient was a 9-year-old male child with complex congenital heart disease and developed the fistula by prolonged tracheal and nasogastric intubation after Fontan type operation. To avoid this unusual but serious complication, aberrant subclavian artery should be treated surgically before repair of complex cardiac anomaly.

Child↗

PubMed1991

[Collins blood diluting reperfusion--an effective measure of controlled reperfusion for the heart hypothermically preserved for 24 hours in modified Collins solution].

Controlled reperfusion is assumed to provide an appropriate environment surrounding the ischemic cardiac tissue at the initial reperfusion phase. Hence, this procedure might play a key role in resuscitating the long term preserved hearts. This study was designed to assess the efficacy of the newly devised reperfusion method; namely Collins Blood Diluting Reperfusion (CBDR), for those hearts subjected to 24-hours cold (4 degrees C) storage in modified Collins (MC) solution. Coronary reperfusion is commenced with the MC solution, and the oxygenated blood is successively added to dilute this perfusate with gradual rewarming under controlled perfusion pressure. Initial reperfusate, therefore, is supposed to be a blood cardioplegia with low Ca2+ and high Mg2+ content. During this procedure, any difference in the ionic composition between the storage solution and the reperfusate is completely abolished and myocardium is free from hastiness of temperature elevation. Using an isolated isovolum contracting heart prepared with an ex vivo apparatus incorporating a support dog, each heart was reperfused by unmodified blood (Group I: n = 7) or CBDR method (Group II: n = 10) under equally controlled low perfusion pressure. There was no difference in the myocardial creatine phosphate level between the 2 groups. However, the adenosine triphosphate content, which had been depleted to 30% of the preischemic level during the 24-hour preservation period, was restored to 52.0% after CBDR procedure (p less than 0.01) and consequently to 57.9% of the control at 60 minutes after reperfusion. Group I showed a significantly lower repletion effect at this phase (41.2% control; p less than 0.05 versus group II).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗

PubMed1991

[Long-term results of porcine bioprosthetic valves].

Between November 1977 and October 1980, 54 patients underwent valve replacements with porcine bioprostheses at Hyogo Kenritsu Amagasaki Hospital. The late complications and the long term durability of 53 porcine bioprostheses were documented in 48 patients after discharge (34 mitral, 7 aortic, 2 tricuspid, and 5 multiple, consisting of 38 Hancock, 15 Carpentier-Edwards prostheses). Cumulative duration of follow-up is 420 patient-years. The valve related late mortality was 0.52%/patient-years. There were 6 thromboembolic events (1.6% patient-years), only 1 episode of endocarditis (0.26%/patient-years). Valve dysfunction is defined as stenosis or regurgitation by echocardiogram or cardiac catheterization. There were 21 instances of porcine bioprosthetic dysfunction (6.6% patient-years). Freedom from valve dysfunction at 12 years was 24.4%. There were 17 valves of mitral bioprosthetic dysfunction (6.4% patient-years). The incidences of mitral stenosis (MS), mitral regurgitation (MR), and paravalvular leakage were 4.5, 3.6, and 0.7%/patient-years respectively. Freedom from MR was higher than MS at 8 years. The 14 patients were needed reoperation due to valve dysfunction (3.6%/patient-years). We concluded that the porcine bioprostheses showed a high incidence of valve dysfunction at 7 to 8 years after operation, we presently choose mechanical valve in most cases.

Adolescent↗

PubMed1990

[A case of right atrial myxoma, originating from the eustachian valve].

We describe a rate of right atrial myxoma, originating from the Eustachian valve, which entered and occupied the right ventricle during the diastolic phase. A 65-year-old woman was admitted with symptoms of palpitation and tachycardiac attack. The condition was diagnosed by echocardiogram and an emergency operation performed. The tumor was removed with the endocardium around 1 cm2 at its stalk in order to prevent recurrence of tumor. No recurrence has developed during the subsequent 2 years 4 months.

Aged↗

PubMed1990

Early and midterm results of the arterial switch operation for transposition of the great arteries in Japan.

A total of 267 infants and children who underwent the arterial switch operation for transposition of the great arteries in the 6 years before Jan. 1, 1988 in six main Japanese institutions were entered into this review. The current status of patients surviving more than 1 year after the operation were evaluated along with early operative results. One hundred forty-six patients had an intact ventricular septum, 103 had a significant ventricular septal defect, and 18 had so-called Taussig-Bing anomaly of the transposition type. Eighteen patients were less than 28 days of age, 73 were 1 to 5 months of age, and 176 were older than 6 months of age at the time of operation. The overall mortality rate was 35% in the first 3 years and 12% in the more recent 3 years. There was a significant difference between the overall mortality rate of primary and two-stage repair (22% versus 10%, p = 0.047) in patients with intact ventricular septum. The overall mortality rate in patients with type B or C coronary arteries of Yacoub, and Radley-Smith's classification was significantly higher than that of other types of arteries (86% versus 18%, p = 0.0001). A total of 156 patients survived more than 1 year after the operation, and 44 children (28%) were noted to have supravalvular pulmonary stenosis (greater than 20 mm Hg). This complication was more common in patients operated on in the newborn period. Trivial or mild aortic regurgitation was noted in 29 patients (19%) and was more common in patients with two-stage than with primary repair (24% versus 14%). Aortic regurgitation was significantly more prevalent in patients in whom coronary arteries were implanted into slits or U-shaped defects than in those whose arteries were implanted into punched-out holes made on the pulmonary root (28% versus 8%, p = 0.049). Normal sinus rhythm was present in 97% of 154 patients and left ventricular ejection fraction was within the normal range in 97% of 115 patients at catheterization 1 to 5 months after the operation.

Aortic Valve Insufficiency↗

PubMed1990

[Right ventricular outflow tract reconstruction with monocusp patch].

Two kinds of monocusp patch were used for reconstruction of right ventricular outflow tract in patients with a variety of congenital heart defects. A bovine pericardial patch with monocusp (MVOP) was used in 11 patients (group M), and a separate transannular outflow patch (STOP) with turned-down equine pericardial monocusp was used in 10 patients (group S). Mean age at operation was 9 years 5 months in group M, and 7 years 9 months in group S. There was one operative death in group M. Survivors have completed a mean follow-up of 19 months. There were no late deaths. In early postoperative period, mean peak systolic pressure gradient between right ventricle and main pulmonary artery was 21 +/- 11 mmHg in group M and 21 +/- 11 mmHg in group S, which were not statistically significant. During follow-up period, no significant increase of peak systolic pressure gradient was noted in both groups. In late postoperative period, pulmonary regurgitation was moderate in 7 and severe in 1 in group M, while it was non-significant in 1, mild in 6 and moderate in 2 in group S. The difference between two groups was significant (p < 0.005). In conclusion, both types of patches equally relieved right ventricular outflow obstruction, but STOP prevented postoperative pulmonary regurgitation more effectively.

Bioprosthesis↗

PubMed1989

Two new loci that give rise to dominant omnipotent suppressors in Saccharomyces cerevisiae.

Ten dominant omnipotent suppressors of Saccharomyces cerevisiae, which were previously shown to be different from SUP46, have been examined. Nine are mapped in a region between lys5 and cyh2 on the left arm of chromosome VII. These suppressors, like SUP46, manifest sensitivity to increased temperature and the antibiotics paromomycin and hygromycin B. In addition, they have an identical action spectrum. These results strongly suggest that they are allelic to each other and they are designated SUP138. The tenth is mapped to a position between his1 and arg6 on the right arm of chromosome V. This suppressor, named SUP139, does not manifest temperature sensitivity nor antibiotic sensitivity. SUP139 and SUP138, which are clearly distinguished by means of action spectrum, act on much fewer nonsense mutations than SUP46. It is now clear that dominant omnipotent suppressors arising at a single locus are homogeneous and that their efficiency is locus-dependent. The order of efficiency is SUP46 greater than SUP138 greater than SUP139.

Alleles↗

PubMed1989

Cardiogenic shock after acute coronary occlusion. Pathogenesis, early diagnosis, and treatment.

The early natural history of left anterior descending coronary artery (LAD) occlusion and the development of cardiogenic shock was studied in 35 open chest anesthetized dogs observed for 6 hours. Six control dogs underwent LAD isolation without occlusion, 13 underwent isolated LAD occlusion to simulate single vessel disease, and 14 underwent LAD occlusion and a 50% left circumflex coronary artery (LCA) stenosis to stimulate multi-vessel disease. Control dogs undergoing anesthesia showed no significant changes in hemodynamics after 6 hours. All dogs with single vessel disease survived and developed immediate and persistent dyskinesis of the anterior wall, a compensatory hypercontractility of remote muscle (131% of control)*, slight energy and substrate depletion and anaerobic metabolism (increased G6P)* despite maintenance of "normal" blood flow through the LCA. In contrast, early mortality was 57% in simulated multi-vessel disease as intractable ventricular fibrillation and/or cardiogenic shock caused the deaths of 7 of 13 dogs (57%)*. Remote muscle became progressively hypocontractile (61% of control)* and caused progressive reduction in stroke work index (less than or equal to 0.5 g x m/kg)*. Remote muscle showed moderate substrate and energy depletion (greater than or equal to 60% fall of ATP and CP, 37% fall of glutamate)* and more pronounced evidence of anaerobic metabolism (G6P rose 373%)* despite "normal" blood flow. These findings suggest that remote muscle is the principle determinant of mortality after an otherwise non-lethal cardiac event.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1989

[Dimensional accuracy of microwave-cured denture base resin].

Recently, microwave-cured denture base resin was developed, and the resin solved the problem of internal porosity which had been generated by curing the conventional denture base resins with microwave irradiation. In this study, the dimensional accuracy of microwave-cured denture base resin was compared with that of other denture base resins, such as pour-type resin, heat-cured resin and heat-shock resin. From the experiment, the following results were obtained. 1. Dimensional accuracy of microwave-cured denture base resin was better than that of heat-cured resin and heat-shock resin, and was similar to that of pour-type resin. 2. Dimensional accuracy of microwave-cured denture base resin by slow cooling method and rapid cooling method was almost the same. Those findings suggest that microwave-cured denture base resin is valuable in clinic.

Denture Bases↗

PubMed1989

[Attempt of analyzing the mandibular movement in three dimensions by computer graphics].

In clinic, simplified mandibular movement measuring devices are used for diagnosis of patients with stomatognathic dysfunction and recording maxillomandibular relation. It is difficult to understand mandibular movement in three dimensions from the path on the three planes, because the path of mandibular movement is in three dimensional space with time, not separately on each plane. The purpose of this study was to develop the three dimensional analyzing system by computer graphics. Mandibular movement was recorded by Mandibular Kinesiograph. The signals were sent to personal computer and the data were processed by the software. The basic specifications of the program were as follows: 1. Data could be observed from various viewpoints. 2. Necessary section of the simultaneous data could be displayed. 3. "C" was used for the software describing language. Following results were obtained: It was possible to analyze the path of mandibular movement in other coordinate axis and understand the path of mandibular movement in three dimensions more accurately.

Computer Graphics↗

PubMed1989

[A case of left ventricular pseudoaneurysm with severe cardiac failure and premature ventricular beats].

A surgically successful case of left ventricular pseudoaneurysm 10 years after an acute myocardial infarction was reported. A 63-year-old man had an acute inferior myocardial infarction 10 years ago. Recently congestive heart failure and premature ventricular beats developed. He was diagnosed as a left ventricular pseudoaneurysm by echocardiogram, CT scan, and left ventriculogram. After the operation, the symptoms diminished and improvement of left ventricular function was observed. A brief review of the literature is given.

Cardiac Complexes, Premature↗

PubMed1989

Studies on prolonged acute regional ischemia. V. Metabolic support of remote myocardium during left ventricular power failure.

This study tests the hypothesis that metabolic support of remote "nonischemic" myocardium during acute infarction will reverse the trend toward cardiogenic shock. Thirty-seven dogs underwent ligation of the left anterior descending coronary artery and 50% stenosis of the circumflex coronary artery. Irreversible ventricular fibrillation developed in 11 of them. The 26 survivors were observed for up to 6 hours; global and regional left ventricular function (cardiac index, stroke work index, ultrasonic crystals) and regional blood flow (radioactive microspheres) were measured. After 2 hours, eight dogs received an intravenous infusion of glutamate/aspartate, glucose-insulin-potassium, coenzyme Q10, and 2-mercapto-propionyl-glycine for 4 hours. Five dogs received the mannitol infusion to raise serum osmolarity 30 mOsm. Four additional dogs received the intravenous substrate infusions over 4 hours without undergoing ischemia. The substrate infusion for 4 hours caused no change in regional or global cardiac function in the four control dogs. Three of nine untreated dogs died of cardiogenic shock, and progressive left ventricular power failure occurred in the six others (40% decrease in cardiac index, 50% decrease in stroke work index, p less than 0.05) because of persistent dyskinesia in the left anterior descending region (-40% of systolic shortening, p less than 0.05) and hypocontractility in the circumflex region (48% of control systolic shortening, p less than 0.05), despite normal transmural blood flow in the posterior left ventricular wall (76 ml/100 gm/min). In contrast, in treated dogs, hypercontractility recovered in the circumflex segment (138% of systolic shortening) and stroke work index rose to control levels (91%) without a change in regional blood flow. Mannitol infusion did not improve hemodynamics or avoid the development of progressive left ventricular power failure. We conclude that cardiogenic shock after myocardial infarction is due, in large part, to impaired ability of "nonischemic" myocardium to maintain hypercontractility. This limitation can be prevented by metabolic support of viable muscle, and the data imply that intravenous substrate infusions may be helpful before definitive treatment (i.e., coronary artery bypass grafting) is undertaken.

Animals↗

PubMed1989

Studies on prolonged acute regional ischemia. I. Evidence for preserved cellular viability after 6 hours of coronary occlusion.

Six hours of coronary occlusion has been thought to produce extensive and irreversible transmural damage and no possibility of salvage by reperfusion. This has been based on findings of adenosine triphosphate depletion and histochemical (triphenyltetrazolium chloride nonstaining) and ultrastructural changes (conventional preparatory techniques). This study tests the hypothesis that, in contrast to conventional wisdom, considerable structural and mitochondrial functional integrity remains in cardiac muscle subjected to 6 hours of regional ischemia. Twenty open-chest anesthetized dogs underwent isolation of the left anterior descending coronary artery and were observed for 6 hours. Eight of the 20 did not undergo ischemia and served as controls. Twelve underwent 6 hours of proximal ligation of the left anterior descending coronary artery (30% +/- 2% area at risk). Transmural biopsy specimens were analyzed. Coronary occlusion reduced regional blood flow (radioactive microspheres) to less than 10 ml/100 gm/min (p less than 0.05) and dyskinesia persisted in the area at risk for 6 hours. High-energy phosphates (adenosine triphosphate and creatine phosphate) declined to negligible levels and histochemical damage occurred (49% +/- 12% triphenyltetrazolium chloride non-staining). Mitochondrial ultrastructural changes (low protein denaturation embedding technique) were mild (the integrity of the inner and outer mitochondrial surface membranes and crystal membranes was maintained and myofibrillar degeneration did not occur). Mitochondrial oxidative phosphorylation rate remained at 63% of control levels, respiratory control index remained at 77%, and adenosine diphosphate/oxygen ratio was maintained at 96%. Mitochondrial Ca++ increased with lanthanum (from 26 to 46 nmol/mg protein, p less than 0.05), but irreversible calcium precipitation did not occur; calcium could be mobilized to normal levels (i.e., 13 nmol/mg protein) by ethylenediaminetetraacetic acid chelation. These data support our inference that necrosis does not occur after 6 hours of coronary occlusion and suggest that muscle salvage by reperfusion is possible after at least 6 hours of regional myocardial ischemia.

Adenosine Triphosphate↗

PubMed1989

Studies on prolonged acute regional ischemia. II. Implications of progression from dyskinesia to akinesia in the ischemic segment.

This study analyzed the pattern of regional wall motion in 58 dogs undergoing 4 to 6 hours of left anterior descending coronary artery occlusion. Regional wall motion was measured by ultrasonic crystals and ischemic muscle either remained dyskinetic (-40% of control systolic shortening, n = 26) or progressed toward akinesia (less than 20% of control systolic shortening or greater than 50% reduction in passive lengthening, n = 32). Ten dogs underwent unmodified blood reperfusion. Regional blood flow (radioactive microspheres), histochemical damage (triphenyltetrazolium chloride staining), and mitochondrial function were determined. Hearts showing persistent dyskinesia had more collateral flow (12 versus 2 ml/100 gm/min, p less than 0.05), less histochemical damage (26% versus 63% area at risk/area of nonstaining, p less than 0.05), and better retention of mitochondrial oxidative phosphorylation capacity (adenosine triphosphate, 622 versus 444 nmol/mg protein/min, p less than 0.05), and tended toward mitochondrial calcium accumulation (48 versus 64 nmol/mg protein). Unmodified blood reperfusion after 4 hours of ischemia produced prompt akinesia (-2% +/- 3% systolic shortening) and was associated with increased edema (82% water content), caused the low-reflow phenomenon (19% control subendocardial flow, 13 ml/100 gm/min), and increased histochemical damage (69% triphenyltetrazolium chloride nonstaining, p less than 0.05). These findings suggest that persistent dyskinesia during early ischemia (first 6 hours) may reflect a relatively optimistic sign, as regression to akinesia occurs in muscle with less collateral flow, more impaired mitochondrial function, worsened calcium homeostasis, and more severe histochemical and ultrastructural damage. These observations imply that careful evaluation of ischemic wall motion may provide a valuable insight into potential muscle salvage.

Adenosine Triphosphate↗

PubMed1989

Studies on prolonged acute regional ischemia. III. Early natural history of simulated single and multivessel disease with emphasis on remote myocardium.

The early natural history of left anterior descending coronary artery occlusion was studied in 35 open-chest anesthetized dogs observed for 6 hours. Six control dogs underwent isolation of the left anterior descending without occlusion, 13 underwent isolated occlusion of the artery to simulate single-vessel disease, and 14 underwent occlusion of the left anterior descending and 50% stenosis of the circumflex coronary artery to simulate multivessel disease. Regional systolic shortening was measured by ultrasonic crystals. Control dogs had a mild fall in cardiac output (27%) and rise in aortic pressure (15 mm Hg). Ischemia produced immediate dyskinesia (-60% of control systolic shortening), and passive lengthening persisted for 6 hours. All dogs with only occlusion of the left anterior descending artery survived (0% mortality). They were less prone to ventricular fibrillation (46% versus 79%, p less than 0.05), developed compensatory hypercontractility of remote muscle (131% of control systolic shortening, p less than 0.05), mild energy and substrate depletion, and anaerobic metabolism (increased glucose-6-phosphate, p less than 0.05) despite maintenance of "normal" blood flow. In contrast, the early mortality rate was 57% (p less than 0.05) when 50% circumflex stenosis coexisted. Intractable ventricular fibrillation and/or cardiogenic shock caused the deaths. Remote muscle became progressively hypocontractile (61% of control systolic shortening, p less than 0.05), with progressive reduction in stroke work index (less than 0.5 gm-m/kg, p less than 0.05). Remote muscle showed moderate substrate and energy depletion (greater than 60% fall of adenosine triphosphate and creatine phosphate, 37% fall of glutamate) and more pronounced evidence of anaerobic metabolism (glucose-6-phosphate rose greater than 400%, p less than 0.05) despite normal blood flow. Mitochondrial ultrastructure and function remained intact in all hearts. These findings suggest that remote muscle is the principal determinant of mortality after an otherwise nonlethal ischemic event. Functional deterioration despite normal blood flow to remote muscle suggests either autoregulatory failure or substrate depletion as a cause of hypocontractility. The structural and functional integrity of mitochondria in ischemic and remote myocardium implies that salvage is possible despite hemodynamic deterioration and intractable ventricular fibrillation.

Adenosine Triphosphate↗

PubMed1989

Studies on prolonged acute regional ischemia. IV. Aggressive surgical treatment for intractable ventricular fibrillation after acute myocardial infarction.

Of 21 dogs undergoing ligation of the left anterior descending coronary artery and 50% stenosis of the left circumflex coronary artery, 15 developed intractable ventricular fibrillation and underwent 1 added hour of femoro-femoral bypass. Three hearts were removed after 1 hour on bypass without myocardial reperfusion for biochemical and mitochondrial analysis. After the 1 hour, five underwent unmodified blood reperfusion on bypass; seven underwent 1 hour of aortic clamping on vented bypass to simulate coronary artery bypass grafting with multidose blood cardioplegic reperfusion. Regional systolic shortening was measured with ultrasonic crystals and cardiac output was measured by thermodilution techniques. All six hearts with no ventricular fibrillation or with reversible ventricular fibrillation and hearts that were not reperfused developed cardiogenic shock (40% decrease in stroke work index, p less than 0.05) because of persistent left ventricular dyskinesia (-40% of systolic shortening, p less than 0.05) and progressive circumflex hypocontractility (48% systolic shortening, p less than 0.05) and showed extensive (68%) triphenyltetrazolium chloride nonstaining. Two dogs died of left ventricular power failure (33% mortality rate). In contrast, 11 of 12 dogs that were reperfused could be weaned from bypass (8% mortality rate). The four dogs surviving after unmodified blood reperfusion (20% mortality rate) showed severe residual left ventricular dysfunction (39% of control stroke work index, p less than 0.05), had equivocal recovery of anterior contractility (10% +/- 7% of systolic shortening), had marginal recovery of contractility in the remote myocardium (60% +/- 11% of systolic shortening), and had extensive triphenyltetrazolium chloride nonstaining (58%). Conversely, all seven dogs with intractable ventricular fibrillation undergoing controlled reperfusion after 4 hours of ischemia recovered normal stroke work index (91%), regained 23% of systolic shortening in the region supplied by the left anterior descending coronary artery (p less than 0.05), 125% of systolic shortening in the circumflex region (p less than 0.05), and showed only 25% triphenyltetrazolium chloride nonstaining (p less than 0.05). These results suggest aggressive treatment of intractable ventricular fibrillation after acute myocardial infarction by providing reperfusion on bypass can salvage hearts thought previously to be damaged irreversibly.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1989

[Evaluation of left ventricular function in the patients with aortic regurgitation following aortic valve replacement by radionuclide cardiography].

Twenty patients undergoing AVR were subjected to this study and divided into the early and the late groups. 6 healthy adults were dealt as the control group. The EF, PER, 1/3 EF, TPE were compared among these three groups both at rest and during exercise. The detailed responses to the exercise were measured by %delta between at rest and during exercise. Furthermore, the LV function in the filling period were examined by the 1/3 FF and RFR at rest. This study suggests that although the left ventricular function and contractile reserve to the exercise remained insufficient in the early postoperative phase, nearly complete recovery of the reserve could be obtained in the later phase, while the left ventricular function in the rapid filling period was significantly decreased in both early and late postoperative phase.

Adolescent↗