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T Masai

Publications and source records attributed to T Masai.

At least 19 recordsLinked to original sources
PubMed2006

[Intermediate results of aortic valve replacement using 19 mm bioprosthetic valve].

Pre- and postoperative hemodynamic parameters and activity of daily life were reviewed to estimate the effectiveness of the valve in 12 cases of single aortic valve replacement (AVR) using 19 mm bioprosthesis. All implanted prostheses were stented-valves. Carpentier-Edwards pericardial valve was used in 7 cases and Mosaic valve in 5. Left ventricular mass index (LVMI) significantly decreased from 167 +/- 36 to 133 +/- 27 g/m2 in the early postoperative period, and to 115 +/- 24 g/m2 in the intermediate phase. However, postoperative LVMI remained higher in patients with body surface area (BSA) over 1.5 m2 than in those under 1.5 m2. Postoperative activity indicated by New York Heart Association (NYHA) grade significantly improved from 2.3 +/- 1.1 to 1.4 +/- 0.5. These results indicates usefulness of 19 mm bioprosthetic valve for reducing left ventricular hypertrophy and improving activity, especially in patients with BSA smaller than 1.5 m2.

Aged↗
PubMed2001

Global and regional cerebral blood flow in neonatal piglets undergoing pulsatile cardiopulmonary bypass with continuous perfusion at 25 degrees C and circulatory arrest at 18 degrees C.

To investigate the influence of hypothermic cardiopulmonary bypass (HCPB) at 25 degrees C and circulatory arrest at 18 degrees C on the global and regional cerebral blood flow (CBF) during pulsatile perfusion, we performed the following studies in a neonatal piglet model. Using a pediatric physiologic pulsatile pump, we subjected six piglets to deep hypothermic circulatory arrest (DHCA) and six other piglets to HCPB. The DHCA group underwent hypothermia for 25 min, DHCA for 60min, cold reperfusion for 10 min, and rewarming for 40 min. The HCPB group underwent 15 min of cooling, followed by 60 min of HCPB, 10min of cold reperfusion, and 30 min of rewarming. The following variables remained constant in both groups: pump flow (150 ml/kg/min), pump rate (150 bpm), and stroke volume (1 ml/kg). During the 60-min aortic crossclamp period, the temperature was kept at 18 degrees C for DHCA and at 25 degrees C for HCPB. The global and regional CBF (ml/100g/min) was assessed with radiolabeled microspheres. The CBF was 48% lower during deep hypothermia at 18degrees C (before DHCA) than during hypothermia at 25 degrees C (55.2 +/- 14.3ml/100g/min vs 106.4 +/- 19.7 ml/100 g/min; p < 0.05). After rewarming, the global CBF was 45% lower in the DHCA group than in the HCPB group 48.3 +/- 18.1 ml/100g/min vs (87 +/- 35.9ml/100g/min; p < 0.05). Fifteen minutes after the termination of CPB, the global CBF was only 25% lower in the DHCA group than in the HCPB group (42.2 +/- 20.7 ml/100 g/min vs 56.4 +/- 25.8ml/100g/min; p = NS). In the right and left hemispheres, cerebellum, basal ganglia, and brain stem, blood flow resembled the global CBF. In conclusion, both HCPB and DHCA significantly decrease the regional and global CBF during CPB. Unlike HCPB, DHCA has a continued negative impact on the CBF after rewarming. However, 15 min after the end of CPB, there are no significant intergroup differences in the CBF.

Animals↗
PubMed2000

Left ventricular myocardial remodeling and contractile state in chronic aortic regurgitation.

BACKGROUND: In chronic aortic regurgitation, eccentric hypertrophy, with combined concentric hypertrophy of the left ventricle, is an important adaptive response to volume overload, which in itself is a compensatory mechanism for permitting the ventricle to normalize its afterload and to maintain normal ejection performance (physiologic hypertrophy). However, progressive dilatation of the left ventricle leads to depressed left ventricular (LV) contractility and myocardial structural changes, including cellular hypertrophy and interstitial fibrosis (pathological hypertrophy). HYPOTHESIS: The study was undertaken to determine the relationship between left ventricular myocardial structure and contractile function in 14 patients with chronic aortic regurgitation by cardiac catheterization and endomyocardial biopsies. METHODS: Myocardial cell diameter and percent interstitial fibrosis were obtained from biopsy samples. Contractile function was evaluated from the ratio of end-systolic wall stress to end-systolic volume index (ESS/ESVI) and the ejection fraction-end-systolic stress (EF-ESS) relationship, which was obtained from 30 normal control subjects. RESULTS: Myocardial cell diameter correlated significantly with the ESVI (r = 0.72, p < 0.005), ejection fraction (r = -0.58, p < 0.05), and ESS/ESVI (r = -0.58, p < 0.05). The percent interstitial fibrosis also correlated inversely with ESS/ESVI (r = -0.71, p < 0.005). Compared with very few patients with an ESVI < 70 ml/m2, the majority of patients with ESVI > or = 70 ml/m2 had a cell diameter of > or = 30 microns and a percent interstitial fibrosis of > or = 10%. The nine patients who had depressed contractile function, as assessed from the EF-ESS relationship, had a higher percent interstitial fibrosis (p < 0.05) than five patients showing a normal EF-ESS relationship, despite the fact that there was no significant difference in myocardial cell diameter between them. Thus, advanced cellular hypertrophy and excessive interstitial fibrosis were significantly and independently associated with myocardial contractile dysfunction and appeared to be responsible for ventricular remodeling. CONCLUSION: Our findings suggest that in many patients with aortic regurgitation, eccentric hypertrophy changes its nature from physiologic to nonphysiologic during the earlier stages in the course of the disease rather than during the stage described previously.

Adolescent↗
PubMed2000

A novel modification of elephant trunk technique using a single four-branched arch graft for extensive thoracic aortic aneurysm.

Surgical repair for the extensive thoracic aortic aneurysm remains unsatisfactory, especially in elderly patients. We developed a total arch replacement with modified elephant trunk technique under moderately hypothermic cardiopulmonary bypass and selective brain perfusion, in which a 4-branched arch graft with a sewing 'collar' enabled the distal anastomosis just proximal to the innominate artery with open distal method and a long 'elephant trunk' was inserted into the descending aorta by the forceps catheter via the femoral artery. This modification is easy and less invasive, and reduces the risk of postoperative complications.

Aged↗
PubMed1999

The effects of a new ultra-short-acting beta-adrenergic blocker, ONO-1101, on cardiac function during and after cardiopulmonary bypass.

The administration of an ultra-short-acting beta-adrenergic antagonist, esmolol, has been introduced as a novel method for beating-heart surgery. In the present study, a new ultra-short-acting beta-blocker, ONO-1101, was administered during cardiopulmonary bypass (CPB) to investigate its effects on cardiac function and hemodynamics. Nine adult mongrel dogs underwent 60 min of CPB during which they were given either ONO-1101 (ONO group; n = 4) or saline (control group; n = 5). In the ONO group, the hearts became flaccid enough for surgery to be performed without cardiac standstill within 10 min after the commencement of ONO-1101 with significant decreases in the heart rate, the preload recruitable stroke work (PRSW), and the slope of the end-systolic left ventricular pressure-volume relationship (Emax). The mean arterial pressure and systemic vascular resistance also decreased, but were maintained above 50 mmHg during CPB without catecholamine. These indices increased to the control group level 20 min after the discontinuation of ONO-1101. The serum concentration of ONO-1101 decreased from the maximum level of 121 +/- 15 microg/ml soon after infusion to 11 +/- 5 microg/ml within 30 min after discontinuation. These data suggest that ONO-1101 may be useful to enable beating-heart surgery to be performed without aortic cross-clamp as an ultra-short-acting beta-adrenergic blocker.

Adrenergic beta-Antagonists↗
PubMed1999

Intraoperative arrhythmias and tissue damage during transmyocardial laser revascularization.

BACKGROUND: Transmyocardial laser revascularization creates transmural channels to improve myocardial perfusion. Different laser sources and ablation modalities have been proposed for transmyocardial laser revascularization. We investigated the incidence of cardiac arrhythmias and laser-tissue interactions during transmyocardial laser revascularization of normal porcine myocardium with three different lasers. METHODS: We used a continuous-wave, chopped CO2 laser (20 J/pulse, 15 ms/pulse) synchronized with the R wave; a holmium:yttrium aluminum garnet (Ho:YAG) laser (2 J/pulse, 250 micros/pulse, 5 Hz); and a xenon-chloride (excimer, Xe:Cl) laser (35 mJ/pulse, 20 ns/pulse, 30 Hz). Each laser was used 30 times as the sole modality in four consecutive pigs, yielding 120 channels. RESULTS: The average number of pulses needed to create a channel was 1, 11 +/- 4, and 37 +/- 8 for the CO2, Ho:YAG, and Xe:Cl lasers, respectively. All Ho:YAG and Xe:Cl channels had premature ventricular contractions. Ventricular tachycardia occurred in 70% of the Xe:Cl and 60% of the Ho:YAG channels. Only 36% of the CO2 channels had premature ventricular contractions, and only 3% of the CO2 channels had ventricular tachycardia (p < 0.001 versus Ho:YAG and Xe:Cl). Ho:YAG channels were highly irregular: each had a 0.6-mm-wide central zone surrounded by a ring of coagulation necrosis (diameter, 1.84 +/- 0.67 mm) with effaced cellular architecture in a thin hemorrhagic zone. The Xe:Cl sections exhibited the same patterns on a smaller scale (diameter, 0.74 +/- 0.18 mm). The CO2 channels were straight and well demarcated. The zone of structural and thermal damage extended over half the channel's diameter, measuring 0.52 +/- 0.25 mm. CONCLUSIONS: During transmyocardial laser revascularization, the CO2 laser synchronized with the R wave is significantly less arrhythmogenic than the Ho:YAG and Xe:Cl lasers not synchronized with the R wave. In addition, the interaction of the CO2 laser with porcine cardiac tissue is significantly less traumatic than that of the Ho:YAG and the Xe:Cl lasers.

Animals↗
PubMed1999

Effects of perfusion mode on regional and global organ blood flow in a neonatal piglet model.

BACKGROUND: Organ injury (brain, kidney, and heart) has been reported in up to 30% of pediatric open heart surgery patients after conventional hypothermic non-pulsatile cardiopulmonary bypass (CPB) support with or without deep hypothermic circulatory arrest (DHCA). The effects of pulsatile (with a Food and Drug Administration approved modified roller pump) versus non-pulsatile perfusion on regional and global cerebral, renal, and myocardial blood flow were investigated during and after CPB with 60 minutes of DHCA in a neonatal piglet model. METHODS: Piglets, mean weight 3 kg, were used in both pulsatile (n = 7) and non-pulsatile (n = 7) groups. After initiation of CPB, all animals were subjected to hypothermia for 25 minutes, reducing the rectal temperatures to 18 degrees C, 60 minutes of DHCA followed by 10 minutes of cold reperfusion and 40 minutes of rewarming with a pump flow of 150 mL/kg/min. During cooling and rewarming, alpha-stat acid-base management was used. Differently labeled radioactive microspheres were injected pre-CPB, on normothermic CPB, pre-DHCA, post-DHCA, and after CPB to measure the regional and global cerebral, renal, and myocardial blood flows. RESULTS: Global cerebral blood flow was significantly higher in the pulsatile group compared to the non-pulsatile group at normothermic CPB (100.4 +/- 6.3 mL/100 gm/min versus 70.2 +/- 8.1 mL/100 gm/min, p < 0.05) and pre-DHCA (77.2 +/- 5.2 mL/100 gm/min versus 56.1 +/- 6.7 mL/100 gm/min, p < 0.05). Blood flow in cerebellum, basal ganglia, brain stem, and right and left cerebral hemispheres had an identical pattern with the global cerebral blood flow. Renal blood flow appeared higher in the pulsatile group compared to the non-pulsatile group during CPB, but the results were statistically significant only at post-CPB (94.8 +/- 9 mL/100 gm/min versus 22.5 +/- 22 mL/100 gm/min, p < 0.05). Pulsatile flow better maintained the myocardial blood flow compared to the non-pulsatile flow after CPB (316.6 +/- 45.5 mL/100 gm/min versus 188.2 +/- 19.5 mL/100 gm/min, p < 0.05). CONCLUSIONS: Pulsatile perfusion provides superior vital organ blood flow compared to non-pulsatile perfusion in this model.

Animals↗
PubMed1999

The effects of pulsatile versus nonpulsatile perfusion on blood viscoelasticity before and after deep hypothermic circulatory arrest in a neonatal piglet model.

Blood trauma increases blood viscoelasticity by increasing red cell aggregation and plasma viscosity and by decreasing cell deformability. During extracorporeal circulation, the mode of perfusion (pulsatile or nonpulsatile) may have a significant impact on blood trauma. In this study, a hydraulically driven dual chamber pulsatile pump system was compared to a standard nonpulsatile roller pump in terms of changes in the blood viscosity and elasticity during cardiopulmonary bypass (CPB) and pre and post deep hypothermic circulatory arrest (DHCA). Piglets, with an average weight of 3 kg, were used in the pulsatile (n = 5) or nonpulsatile group (n = 5). All animals were subjected to 25 min of hypothermia, 60 min of DHCA, 10 min of cold reperfusion, and 40 min of rewarming with a pump flow of 150 ml/kg/min. A pump rate of 150 bpm, pump ejection time of 120 ms, and stroke volume of 1 ml/kg were used during pulsatile CPB. Arterial blood samples were taken pre-CPB (36 degrees C), during normothermic CPB (35 degrees C), during hypothermic CPB (25 degrees C), pre-DHCA (18 degrees C), post-DHCA (19 degrees C), post-rewarming (35 degrees C), and post-CPB (36 degrees C). Viscosity and elasticity were measured at 2 Hz and 22 degrees C and at strains of 0.2, 1, and 5 using the Vilastic-3 Viscoelasticity Analyzer. Results suggest that the dual chamber neonate-infant pulsatile pump system produces less blood trauma than the standard nonpulsatile roller pump as indicated by lower values of both viscosity and elasticity during CPB support.

Animals↗
PubMed1998

A novel technique for cardiopulmonary bypass using vacuum system for venous drainage with pressure relief valve: an experimental study.

To decrease the circuit priming volume, develop safety, and simplify the equipment, a cardiopulmonary bypass (CPB) circuit using a vacuum suction venous drainage system with a pressure relief valve was developed. The efficacy of this vacuum system was compared to that of a conventional siphon system. The system contains a powerful vacuum generator and a pressure relief valve to keep the negative pressure constant when blood suction is used. Using 8 mongrel dogs, the feasibility and the efficacy of this CPB system was tested. The changes in the negative pressure in the reservoir were within 5 mm Hg whether the suction lines were switched on or off. In all animals the amount of blood in the venous reservoir was stable throughout bypass. The decrease of priming volume was from 725 ml (siphon system) to 250 ml (vacuum system). At the end of CPB, the levels of hemoglobin in the vacuum system were significantly higher than those in the siphon system. These results demonstrated that this vacuum drainage system can provide simplification and a miniaturization of the cardiopulmonary bypass circuit resulting in low hemodilution during CPB.

Animals↗
PubMed1997

Myocardial histological changes in dilated cardiomyopathy during a long-term left ventricular assist device support.

As the myocardium in patients with dilated cardiomyopathy (DCM) is deteriorating progressively, resulting in a decrease in left ventricular function, patients with end-stage DCM may require implantation of a left ventricular assist device (LVAD) unless they undergo heart transplantation. Although LVAD has been reported to provide excellent hemodynamic support, no data are currently available about the effects of long-term LVAD support on the myocardium in patients with DCM. We describe two patients with end-stage DCM who underwent LVAD implantation and were supported with LVAD for 524 and 245 days, respectively. Serial myocardial biopsies showed increases in myocardial cell diameter and intercellular fibrosis, despite excellent hemodynamic support by LVAD. These data suggest that the myocardium in patients with end-stage DCM deteriorates progressively, even if the pre-load of the left ventricle is reduced by LVAD.

Adult↗
PubMed1997

Effect of cardiopulmonary bypass under tepid temperature on inflammatory reactions.

BACKGROUND: Cardiopulmonary bypass (CPB) causes inflammatory reactions and abnormal responses of vascular resistance. Theoretically, the difference in the blood temperature during CPB may influence the degree of CPB-induced inflammatory reactions. METHODS: To elucidate the effect of the perfusate temperature during CPB, serum levels of inflammatory cytokines, neutrophil elastase, complements, and vasoactive substances were measured in 18 patients undergoing elective coronary artery bypass grafting under tepid temperature (34 degrees C) and moderate hypothermia (28 degrees C). Respiratory index and systemic vascular resistance index during and after CPB and intubation time after postoperative course were also analyzed. RESULTS: The patterns of the change in interleukin-8 and neutrophil elastase were significantly different between the two groups. The tepid group showed an earlier decrease in interleukin-8 and neutrophil elastase levels as compared with the hypothermic group. The prostaglandin E2 level just after CPB was significantly higher in the tepid group than in the hypothermic group. Systemic vascular resistance index and respiratory index and intubation time were significantly lower in the tepid group than in the hypothermic group. CONCLUSIONS: These results demonstrated that tepid CPB affected the inflammatory cytokine release and neutrophil activation compared with hypothermic CPB, resulting in the attenuation of respiratory dysfunction. This may suggest a beneficial effect of tepid temperature in CPB with possible attenuation of the postperfusion syndrome.

Bradykinin↗
PubMed1997

Biocompatibility of heparin-coated circuits in pediatric cardiopulmonary bypass.

In this study, we evaluated the biocompatibility of heparin-coated circuits in pediatric cardiopulmonary bypass (CPB). Eight patients were divided into 2 groups: the control group (Group C) and heparin-coated group (Group H). In Group H, CPB circuits, including the arterial pump, oxygenator, and cannulas were heparin-coated. Before, during, and after CPB, blood samples were obtained to assess the platelet counts (Plat), alpha 2-plasmin plasminogen inhibitor complex (PIC), thrombin-antithrombin III complex (TAT), C3 activation products (C3a), interleukin (IL)-6, IL-8, and polymorphonuclear neutrophil leukocyte (PMN) elastase. There was no significant difference in Plat, PIC, or TAT between groups. Group H showed significantly low levels of C3a (during and after CPB), PMN elastase (during CPB), and IL-6 (after CPB). These data demonstrated that in pediatric CPB, heparin-coated CPB circuits reduced the activation of complements and the production of PMN elastase and IL-6, suggesting the superior biocompatibility of the heparin-coated circuits.

Anticoagulants↗
PubMed1996

Emergency cardiopulmonary bypass support in patients with severe cardiogenic shock after acute myocardial infarction.

A total of 16 patients who developed severe cardiogenic shock were resuscitated with a percutaneous cardiopulmonary support system (PCPS). The etiology of shock was acute myocardial infarction (n = 7), or post-infarction left-ventricular (LV) free wall rupture (n = 9). After successful resuscitation with the PCPS, 15 patients underwent therapeutic interventions: closure of an LV rupture (n = 9), coronary artery bypass grafting (n = 4), percutaneous transluminal angioplasty (n = 1), and percutaneous transluminal coronary recanalization (n = 1). Of the 16 patients, 14 were weaned from PCPS or standard cardiopulmonary bypass. Six patients survived longer than 30 days, 3 (19 percent) of whom were discharged from the hospital. The long-term survival rate in the 6 patients who underwent coronary revascularization was 33 percent (2/6). Of the 9 patients with LV free wall rupture, 1 was discharged from the hospital. Even though it cannot be concluded, from this small number of patients, that cardiopulmonary resuscitation using PCPS improves survival, it appears that PCPS is a powerful resuscitative modality for seriously ill patients with acute myocardial infarction or LV rupture.

Aged↗
PubMed1996

Repair of postinfarction ventricular septal defect on a beating heart.

Two elderly patients with postinfarction ventricular septal defect underwent repair by endocardial patch with infarct exclusion on a beating heart under normothermic cardiopulmonary bypass with ultra-short-acting beta-blocker infusion. Their hemodynamic states soon recovered, and postoperative angiographic studies showed improvement of cardiac function and no residual shunt. Ultra-short-acting beta-blocker has the potential to facilitate safe repair of postinfarction ventricular septal defect on a beating heart, and this operative approach can be beneficial for myocardial protection.

Adrenergic beta-Antagonists↗
PubMed1996

Attenuation of cardiopulmonary bypass-derived inflammatory reactions reduces myocardial reperfusion injury in cardiac operations.

In cardiac operations endopeptidase (protease) inhibitor may be beneficial in reducing myocardial injury when administered in the cardiopulmonary bypass prime. Nafamostat mesilate was evaluated in 20 patients who underwent coronary artery bypass grafting. The patients were divided into a control group (n = 10) and a nafamostat group (n = 10). Nafamostat (2 mg/kg per hour) was continuously given during cardiopulmonary bypass in the nafamostat group. The age, number of grafts, cardiopulmonary bypass time, and aortic crossclamp time were similar between groups. In the control group, neither tumor necrosis factor-alpha nor interleukin-1 levels showed any significant change during cardiopulmonary bypass, whereas interleukin-6 and interleukin-8 levels, percent expression of adhesion molecule (CD18) on neutrophils, and CH50 assay results increased significantly during cardiopulmonary bypass. As compared with the control group, the nafamostat group showed significantly lower levels of interleukin-6 (123 +/- 57 versus 40 +/- 22 pg/ml, respectively) and interleukin-8 (96 +/- 13 versus 66 +/- 14 pg/ml, respectively). The nafamostat group showed a significantly lower difference of CH50 assay results and malondialdehyde levels between coronary sinus blood and arterial blood and peak values of creatine kinase MB (43 +/- 12 IU/L versus 19 +/- 6 IU/L) during the postoperative course compared with findings in the control group. These results demonstrated that inflammatory reactions induced by cardiopulmonary bypass had adverse effects on myocardial recovery after aortic crossclamping and that nafamostat mesilate given during cardiopulmonary bypass appeared to reduce myocardial reperfusion injury by attenuating such inflammatory reactions. Attenuation of inflammatory reactions of cardiopulmonary bypass should be considered in the strategy of myocardial protection.

Benzamidines↗
PubMed1996

Onset of Graves' thyrotoxicosis after an attack of allergic rhinitis.

We previously reported that allergic rhinitis was an aggravating factor for Graves' disease and that thyrotoxicosis relapsed 2 months after an allergic attack. In this paper, we report a patient who showed onset of Graves' thyrotoxicosis after an attack of allergic rhinitis. The patient, a 30-year-old woman, was initially diagnosed with subclinical autoimmune thyroiditis. Interestingly, the patient showed weak activity of thyroid-stimulating antibody (TSAb), while TSH-binding inhibitory immunoglobulin (TBII) was negative and her thyroid function tests, including TSH, were completely normal. The patient developed severe allergic rhinitis in response to Japanese cedar pollen lasting from February until April in 1995 with an increase in serum antigen-specific immunoglobulin E and peripheral blood eosinophils. Two months later, she developed thyrotoxicosis in association with increase in TSAb and TBII. These findings suggest that allergic rhinitis not only aggravates Graves' disease but also induces the clinical onset of Graves' thyrotoxicosis.

Adult↗
PubMed1996

[Coronary artery bypass grafting under bradycardia induced by ultra-short acting beta blocker].

From Dec. 1993 to May, 1994, coronary artery bypass grafting (CABG) was performed in 7 patients under bradycardia induced by an ultra-short acting beta blocker (esmolol). The ages ranged from 51 to 68 years. There was one patient with low ejection fraction (EF = 31%) and two patients with porcelain aorta. A tepid temperature was maintained during cardiopulmonary bypass (CPB). A high flow rate of 2.2-2.6 liter/min/m2 was applied to control perfusion pressure above 50 mmHg during CPB. After CPB was started, a high dose of esomolol was added (10-30 mg/kg intravenous bolus followed by a continuous infusion of 1-4 mg/kg/min). Severe bradycardia was achieved by the initial loading of esmolol. The mean heart rate was significantly (p < 0.01) decreased from 78 +/- 12 bpm to 49 +/- 7 bpm by the loading. Altogether, 25 anastomoses (11 ITA, 6 GEA, 8 SVG) were performed to LAD (10), Cx (7) and RCA (8), with an average of 3.6 +/- 0.9 anastomoses/patient. IABP was required for 2 patients postoperatively. There was no operative death, but one hospital death due to aspiration pneumonia 3 months later. Postoperative max CPK-MB was low (17.4 +/- 9.7 IU/L) in 6 patients. The postoperative angiography was performed in all patients with a patency rate of 88%. It was considered that esmolol facilitated CABG under beating heart and this technique is suitable for patients with severe atheromatous disease of the ascending aorta or patients with a low ejection fraction to avoid aortic cross-clamping.

Adrenergic beta-Antagonists↗