Biomedical subjects

M Ohmi

Publications and source records attributed to M Ohmi.

At least 55 records · Page 3Linked to original sources

PubMed1996

Extracardiac conduit composed of gutter-shaped prosthesis and pedicled pericardial valved patch for pulmonary trunk reconstruction.

A conduit for reconstruction of the pulmonary trunk is presented. A Gelseal vascular prosthesis (Vascutek Ltd, Inchinnan, Scotland) was split longitudinally in two halves, and one half was used as a posterior wall of the conduit like a gutter. The anterior wall was constructed by a pedicled pericardial valved patch. Finally, the proximal anastomosis of the conduit was completed with a gusset cut from the Gelseal prosthesis. This conduit can be applied to patients who require the Rastelli procedure, and growth potential of the pedicled pericardial patch may be expected.

Blood Vessel Prosthesis↗

PubMed1996

Effects of cardiac surgery on intellectual function in infants and children.

Intellectual function was evaluated by Gesell's developmental quotient (DQ) and Binet's intelligence quotient (IQ) in 161 infants and children (61 ventricular septal defects, 49 tetralogies of Fallot, 15 transpositions of the great arteries, seven atrial septal defects, five complete atrioventricular canals, five double outlet right ventricles and 19 shunt cases; average age 3.6 years) before and after cardiac surgery. There were no significant differences in preoperative DQs and IQs among the patient groups. Although average DQ scores in 21 infants with hypothermic (13-24 degrees C) total circulatory arrest (36-70 min) were not significantly different from the preoperative values, 13 patients with an arrest time > 50 min showed a significant decrease in DQ scores. The postoperative DQ and IQ scores in patients without circulatory arrest or in shunt cases were not significantly impaired after surgery. It was concluded that cardiac surgery did not impair intellectual function in infants and children, although cerebral dysfunction might occur if circulatory arrest was > 50 min.

Adolescent↗

PubMed1996

Egocentric perception through interaction among many sensory systems.

We perceive the egocentric position and velocity of ourselves by many senses, such as vision, proprioception and vestibular sense. Normally the information by these senses is in harmony. However, there are situations in which the information is inharmonious. When we watch a wide-screen monitor or we ride in an accelerating or turning vehicle, visual information conflicts with proprioceptive and vestibular information. Since human egocentric perception has been studied for each separate sense in the previous research, it is not clear how the integration among these senses contributes to perception of human orientation. In Experiment 1, we investigated the contribution of visual, proprioceptive and vestibular information in isolation and in combination to perception of direction of forward self-motion. An observer rode in small vehicle (vestibular information) or walked (proprioceptive information) through a narrow corridor. Many vertical bars were hung from a ceiling of the corridor. When the observer moved forward, she/he viewed expanding optic flow of the bars (visual information) through video cameras and a helmet-mounted stereoscopic display. By fastening the observer and/or the cameras at different angles, consistent or conflicting information about forward direction was given through each sense. It was found that when there was conflicting information about the direction of forward motion (a) vestibular information was more dominant than visual cute, (b) visual and proprioceptive information was linearly added with weighting, and (c) visual information was dominant for backward motion. In Experiment 2, we investigated sensory integration when we moved forward with linear acceleration. Direction of the acceleration was either forward or sideways, namely corresponding to a ride in an accelerating or turning vehicle. We developed a new method to measure sensation or self-motion more objectively by using the three-dimensional position-sensor system. Positions of observer's head, shoulder, waist and ankle were measured to find body tilt accompanied by sensation of self-motion. It was found that the body tilted towards the opposite direction of the self-acceleration and the angle of body tilt was in good agreement with the subjective amount of the accelerating sensation. The body tilt was even induced by solely visual information. This implied that visual information contributed to perception of self-acceleration as well as self-motion.

Evoked Potentials, Somatosensory↗

PubMed1996

Effects on visual functions during tasks of object handling in virtual environment with a head mounted display.

This study examined the effects on visual functions of a prolonged handling task within the helmet-mounted display environment. Both version eye movement and accommodative response became gradually slower during the 40-min task. Although delayed presentation of display after head movement noticeably worsened both visual responses, presentation delay after hand movement did not significantly change the sluggishness of responses. Therefore it is suggested that decreasing time delay after head movement is a more important factor in order to improve human performance of handling tasks within the HMD environment.

Accommodation, Ocular↗

PubMed1996

[Acute aortic dissection with leg ischemia].

From January of 1987 to July of 1994, 83 patients with acute aortic dissection were treated at our institution. Of these, 7 patients (8%) sustained acute leg ischemia. Angiography showed that one patient had arterial occlusion at the abdominal aorta, three had occlusion at the right common iliac artery, and one had severe right common iliac artery stenosis. Four patients with acute type A dissection underwent emergency replacement of the aortic arch and/or ascending aorta. Three of them were discharged, but one patient died due to renal failure and multiple organ failure. In three patients with acute type B dissection, one with aortic rupture was successfully treated by replacement of the descending thoracic aorta; of the other two who received bypass operations for leg ischemia, one died due to myonephropathic metabolic syndrome and sepsis which were caused by a delay in surgery. In conclusion, emergency thoracic aortic repair should be performed in acute type A dissection with leg ischemia, whereas bypass operation for ischemic leg should be considered in patients of acute type B dissection with leg ischemia when they are not complicated with rupture or visceral ischemia.

Acute Disease↗

PubMed1995

Heading judgments during active and passive self-motion.

Previous studies have generally considered heading perception to be a visual task. However, since judgments of heading direction are required only during self-motion, there are several other relevant senses which could provide supplementary and, in some cases, necessary information to make accurate and precise judgments of the direction of self-motion. We assessed the contributions of several of these senses using tasks chosen to reflect the reference system used by each sensory modality. Head-pointing and rod-pointing tasks were performed in which subjects aligned either the head or an unseen pointer with the direction of motion during whole body linear motion. Passive visual and vestibular stimulation was generated by accelerating subjects at sub- or supravestibular thresholds down a linear track. The motor-kinesthetic system was stimulated by having subjects actively walk along the track. A helmet-mounted optical system, fixed either on the cart used to provide passive visual or vestibular information or on the walker used in the active walking conditions, provided a stereoscopic display of an optical flow field. Subjects could be positioned at any orientation relative to the heading, and heading judgments were obtained using unimodal visual, vestibular, or walking cues, or combined visual-vestibular and visual-walking cues. Vision alone resulted in reasonably precise and accurate head-pointing judgments (0.3 degrees constant errors, 2.9 degrees variable errors), but not rod-pointing judgments (3.5 degrees constant errors, 5.9 degrees variable errors). Concordant visual-walking stimulation slightly decreased the variable errors and reduced constant pointing errors to close to zero, while head-pointing errors were unaffected.

Adult↗

PubMed1995

[Separate perfusion of upper and lower body under mild hypothermia during operation on the thoracoabdominal aorta].

During last 7 years, we performed 24 operations on the thoracoabdominal aorta. There were 9 true and 15 dissecting aneurysms. There were two cases of ruptured aneurysm and thoracoabdominal replacement was performed as a last stage operation for total aortic replacement in 4 cases. Three cases with aortic dissection died within 30 days after surgery. Femoro-femoral bypass was used in 4 cases (1 case died of brain damage, paraplegia and MOF), left heart bypass in 5 cases and separate perfusion of upper and lower body (SPULB) under deep hypothermia in 7 cases (2 cases died of LOS and cerebrovascular accident occurred at 2 weeks after operation) and SPULB with mild hypothermia in 8 cases for circulatory support. There was one case of renal dysfunction and transient mild liver dysfunction occurred in 7 cases. There was no evidence on relationship between surgical outcome and methods of circulatory supports, but we recently prefer SPULB under mild hypothermia for thoracoabdominal surgery since intraoperative massive bleeding and cardiac arrest can be easily treated and major organs can be protected by introducing hypothermia in this perfusion technique.

Adult↗

PubMed1995

[Dislodgement of the ringed-graft--a case report].

A 70-year-old man underwent replacement of the distal aortic arch which contained a huge aneurysm using a ringed graft. He died suddenly of hemoptysis 54 months following the operation. An autopsy revealed dislodgement of the spool on the posterior aspect of the aorta. Histologic examination of the dislodged portion of the ring showed complete disruption of the intima and elastic fibers of the media. There were minimal histologic changes in the anterior portion of the anastomotic site. It is postulated that the long, kinked graft might have caused the late ring dislodgement.

Aged↗

PubMed1995

[Mitral valvuloplasty for an infant with congenital mitral stenosis-- report of a case].

A 7-month-old infant, who underwent repair of coarctation of the aorta four months ago, was readmitted for heart and respiratory failure. Preoperative serial echocardiographic studies revealed progression of mitral valvular and subvalvular stenosis. At operation the mitral valve apparatus was found to be funnel-shaped type of congenital mitral stenosis. Chordae fenestration, papillotomy and commissurotomy were performed. Intraoperative transesophageal echocardiography demonstrated increased inflow through the mitral valve apparatus. Postoperative course was uneventful, and she was discharged 28 days after operation.

Female↗

PubMed1995

[Hemodynamic response to pericardiectomy in the patients with constrictive pericarditis: with reference to surgical approaches and responses to exercise].

Between 1975 and 1994, we performed 20 pericardiectomies for 19 patients with constrictive pericarditis (CP) through a median sternotomy (13 cases), a left thoracotomy (2 cases), a median sternotomy combined with a left thoracotomy (4 cases) or a median sternotomy under ECC (1 case). One patient died from LOS at 1st POD due to myocardial failure. Pericardiectomy through a median sternotomy decreased RA pressure but PAW pressure did not decrease in some patients. On the contrary, pericardiectomy through either a left thoracotomy or a median sternotomy combined with a left thoracotomy decreased PAW pressure as well as RA pressure significantly. Responses to bicycle exercise demonstrated marked elevation of RA and PAW pressures even in a mild case of CP, so that the exercise testing seems to be useful for early detection of CP and evaluation of the operative results.

Adolescent↗

PubMed1995

[Surgical treatment of type A aortic dissection based on the location of the entry].

From 1987 to February of 1994, 42 cases of acute aortic dissection and 31 cases of chronic dissection have been operated in out institution. Our surgical technique for the treatment of aortic dissection is a tubular graft replacement following a resection of the segment of aorta containing the intimal tear. The location of the entry was, therefore, important to determine the extension of graft replacement and to select the circulatory support method during operation. 52%, 33% and 14% of cases in acute aortic dissection had entries in ascending, arch and descending aorta, respectively. Entries of 52%, 32% and 16% of cases in chronic dissection located in ascending, arch and descending aorta, respectively. In cases with the entry in ascending aorta, ascending aorta and partial aortic arch replacement was performed in 12 and 10, respectively, for acute dissection, whereas more extensive graft replacement procedure was selected for chronic dissection including complete arch replacement in three cases and two of them had concomitant Bentall type operation. Likewise, with the entry in aortic arch, partial arch replacement was performed more often in 9 than complete arch replacement in 5 for acute dissection, on the other hand, complete arch replacement procedure tended to be preferable in 6 cases for chronic dissection. For retrograde dissection with the entry in descending aorta, ascending aorta and complete arch replacement were performed in 4 and 6 cases, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Aortic arch aneurysm repair using selective cerebral perfusion.

Seventy-seven patients underwent aortic arch aneurysm repair using selective cerebral perfusion from January 1987 to August 1992. Early and long-term results and preoperative and postoperative cerebral function were evaluated. Cerebral function was assessed by the mini mental state-Himeji test and the Wechsler adult intelligence scale. Thirty-six patients had true aneurysms, and 41 had dissection. Hospital mortality for true and dissecting aneurysms was 19.4% and 7.3%, respectively. The 5-year actuarial survival rates for true and dissecting aneurysms were 59.0% and 65.3%, respectively (not significant). There were no significant differences in test scores before or after operation. Repair or replacement of the aortic arch using selective cerebral perfusion is a safe procedure with acceptable hospital mortality.

Aortic Dissection↗

PubMed1994

[Staged operation for aneurysm of the entire aorta: report of four cases].

Between September 1989 and May 1994, 3 patients with aortic dissection and one with atherosclerotic total aortic aneurysm associated with annuloaortic ectasia underwent successful staged operation for aneurysm of the entire aorta and aortic regurgitation. A composite graft was used for total aortic root replacement. Carbrol and Piehler techniques, Carrel patch and saphenous vein grafting were employed for coronary artery reconstruction. En bloc arch reconstruction was performed in one patient and three vessels graft replacement in 3 patients under hypothermic separate cerebral perfusion. Combined antegrade with retrograde oxygenated crystalloid cardioplegia and terminal warm blood cardioplegia were used for myocardial protection during prolonged aortic cross clamping in a simultaneous total aortic root and arch replacement. Elephant trunk was used at the distal arch anastomosis in 3 patients and useful for following thoracoabdominal surgery. In 3 patients, separate perfusion of upper and lower body technique with moderate hypothermia was employed and seemed to be useful in the patients who require extensive thoracoabdominal replacement to prevent spinal cord injury. All patients had no major complications and have been well.

Adult↗

PubMed1994

Thoracic aortic aneurysmectomy with a sutureless intraluminal ringed graft.

Forty-two patients underwent replacement of the thoracic aorta with a sutureless intraluminal graft. Early and long-term results were evaluated. The operative mortality rate was 7.1%. There were two postoperative complications related to a ringed graft. One complication, the formation of a pseudoaneurysm, was caused by insufficient fixation of the graft; the other, a cerebral infarction, was related to the location of the proximal anastomosis with respect to the origin of the left subclavian artery. The 3- and 5-year actuarial survival rates were 86 and 69.5%, respectively. These were similar to survival rates of age-matched controls in the general Japanese population. Replacement of the thoracic aorta using a sutureless intraluminal graft can be performed with acceptable operative mortality, with good long-term results.

Adult↗

PubMed1994

[Comparison of the late hemodynamics following corrective surgery of congenital heart diseases: ventricular septal defect, tetralogy of Fallot, Mustard operation and Fontan operation].

Late hemodynamics following corrective surgery for congenital heart diseases were evaluated in 65 patients. The patients were divided into 4 groups due to the operative procedures including closure of ventricular septal defect (VSD group = 15 patients), repair of tetralogy of Fallot (TOF group = 20), Mustard operation (Mustard group = 19) and Fontan operation (Fontan group = 11). The postoperative period was 3.8 +/- 3.8, 1.0 +/- 0.1, 5.7 +/- 4.3 and 3.2 +/- 4.9 years in VSD, TOF, Mustard and Fontan groups, respectively. Postoperative pulmonary to systemic arterial pressure ratio in VSD group significantly decreased to 0.38 +/- 0.13 from the preoperative value of 0.97 +/- 0.04. Pulmonary vascular resistance (Rp) in VSD group significantly decreased from 4.88 +/- 2.40 to 2.56 +/- 0.75 U.m2 and Rp in Fontan group significantly increased from 1.63 +/- 0.70 to 3.66 +/- 0.47 U.m2 postoperatively. Postoperative cardiac indices in VSD, TOF, Mustard and Fontan groups were 4.30 +/- 1.34, 4.28 +/- 0.72, 3.83 +/- 1.38 and 3.48 +/- 1.38 l/min/m2, respectively, without significant differences. Ejection fraction (EF) of the systemic ventricle (left ventricle) in VSD, TOF and Fontan groups were 0.66 +/- 0.06, 0.65 +/- 0.07 and 0.63 +/- 0.08, respectively. In Mustard group, EF of the systemic ventricle (right ventricle) was 0.56 +/- 0.12 and significantly less than left ventricular EF in the other 3 groups. The hemodynamic characteristics after these operative procedures should be considered for patient management.

Cardiac Surgical Procedures↗

PubMed1993

Cyclovergence: a comparison of objective and psychophysical measurements.

Several psychophysical procedures have been used to measure cyclovergence but none has been adequately validated with respect to an objective measure. Scleral search coils were used to measure cyclovergence induced by dichoptic textured patterns which cyclorotated in antiphase through 6 degrees at frequencies between 0.05 and 2 Hz. In one psychophysical procedure subjects nulled the apparent oscillatory motion of radial nonius lines superimposed on a small black disc at the center of a large cyclorotating display. In the second, subjects nulled the apparent inclination in depth of a vertical line displayed in the same way. The amplitude of cyclovergence measured objectively and the magnitude of oscillation of the nonius lines were similar at low stimulus frequencies. At higher frequencies of cyclorotation, both amplitudes declined but the nonius amplitude exceeded that of cyclovergence. The apparent inclination of the vertical test line, as indicated by the nulling procedure, also declined with increasing frequency of cyclorotation, but not at the same rate. At low frequencies, the apparent inclination of the test line was greater than that corresponding to the cyclodisparity induced into the line and almost as great as that corresponding to the relative disparity between the oscillating pattern and the line. The implications of these results for measuring cyclovergence and for an understanding of stimuli driving cyclovergence and perceived inclination in depth are discussed.

Eye Movements↗

PubMed1993

Replacement of the transverse aortic arch for type A acute aortic dissection.

Surgical treatment of acute aortic dissection involving the segment of transverse aortic arch is difficult and often associated with a high mortality and morbidity. The high mortality and morbidity are primarily related to anatomic features and techniques of cerebral protection employed during the period of aortic branch occlusion needed for reconstruction. This study reports our experience of 20 consecutive cases of acute type A aortic dissection treated by repair or replacement of the transverse aortic arch during emergency operation. Ages of the patients ranged from 56 to 76 years. All patients were referred to us within 2 weeks of onset (mean time, 58 hours). Selective cerebral perfusion or deep hypothermia with complete circulatory arrest was employed during the period of aortic branch occlusion. Duration of cerebral perfusion, circulatory arrest, myocardial ischemia, and cardiopulmonary bypass averaged 106 minutes, 32 minutes, 127 minutes, and 248 minutes, respectively. There were three operative deaths. All three dissections were ruptured ones, and the patients died of hemorrhage, deep coma, or multiple organ failure. One patient died of infection 3 months after operation. The remaining patients are alive and well without any detectable neurological deficit 1 month to 4 years postoperatively. This experience emphasizes that repair or replacement of acute type A aortic dissection involving the aortic arch can be performed safely by adequate selection of patients, supportive measures, and operative methods.

Acute Disease↗

PubMed1993

Protection of the brain during hypothermic perfusion.

The adequacy of the circuits for brain perfusion has been explored by hemodynamic assessment using the ability of the brain to autoregulate blood flow as an indicator, and by morphologic observation using carbon black or Evans blue infusion into the brain perfused antegradely or retrogradely. It is concluded that the safe pressure of cerebral perfusion needed to maintain cerebral integrity is between 40 and 50 mm Hg in both normothermic and hypothermic perfusions, a pressure that can be generated by nonpulsatile pump flows through the pump greater than 40 mL.kg-1 x min-1. Morphologic studies revealed development of focal infarctions in the brain and destruction of the blood-brain barrier by retrograde cerebral perfusion. The retrograde approach, therefore, is definitely inferior to the antegrade method. Antegrade perfusion for 90 minutes, however, produced minimal cerebral edema, suggesting the need for further improvement even in techniques of antegrade perfusion.

Animals↗