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Biomedical subjects

A T Kawaguchi

Publications and source records attributed to A T Kawaguchi.

At least 19 recordsLinked to original sources
PubMed2001

Partial left ventriculectomy. The First Japanese Registry Report 1999.

OBJECTIVE: Partial left ventriculectomy has been performed without standardized inclusion/exclusion criteria. A registry has been established to accumulate experience with this procedure to identify indications, risks and benefits. METHODS: In response to a mailed inquiry, 90 cases were voluntarily registered from 28 Japanese institutions. RESULTS: Males (n = 67, 74.4%) predominated, and 29 (32.2%) patients were over 60 years old. The underlying cardiac pathologies included dilated cardiomyopathy (n = 75, 83.3%), valvular disease (n = 8, 8.9%), the dilated phase of hypertrophic cardiomyopathy (n = 4, 4.5%), and others (n = 3, 3.3%). Gender, age, etiology, papillary muscle excision and absent transplant indication did not significantly affect survival. Poorer preoperative condition, reduced contraction and decompensation necessitating emergency operation were each associated with a significantly higher risk. Hospitals performing less than 5 cases had poorer results than more experienced institutions (p = .0019), which showed a tendency towards improved survival in the second half of their experience (p = .096). Hospital mortality (n = 29, 32.6%) and late death (n = 10, 11.2%) were mainly from ventricular failure with few sudden deaths over a period of 63.6 patient years follow-up. Late mortality was equally distributed in the first year and leveled off with significantly improved cardiac functional class in survivors. CONCLUSION: Partial left ventriculectomy was associated with better survival in less symptomatic patients with better contractile reserve undergoing an elective operation preserving the papillary muscles. Avoidance of identified risk factors may allow better patient selection and improved survival in the current environment where rescue transplantation is not readily available. Long-term follow-up is warranted with more registry data.

Aged↗
PubMed2001

Two-week, but not 1-week, hypoxic exposure enhances nitric oxide-mediated basal tone regulation in rat resistance pulmonary arteries.

We measured internal diameter (ID) changes in resistance and conduit pulmonary arteries of 1- and 2-week hypoxic rats and normoxic control rats in response to nitric oxide synthase (NOS) inhibitors in vivo. At 2 weeks of hypoxic exposure, the ID reduction as a result of NOS inhibition was enhanced within the resistance arteries, but not at 1 week of hypoxia.

Animals↗
PubMed2000

Magnetic resonance arthrography in children with developmental hip dysplasia.

Conventional and gadolinium enhanced magnetic resonance arthrograms were done on 14 hips in 10 children ages 7 to 24 months. The contralateral normal hips in those with unilateral disease were studied with unenhanced magnetic resonance imaging for comparison. By conventional arthrography, there were no well visualized structures. Visualized structures seen as filling defects were the labrum, ligamentum teres, and transverse acetabular ligament. By magnetic resonance arthrography, well visualized structures were the labrum, ligamentum teres, transverse acetabular ligament, and pulvinar. By unenhanced magnetic resonance imaging, well visualized structures were the labrum, ligamentum teres, and transverse acetabular ligament. The difference in visualization by magnetic resonance arthrography versus conventional arthrography was statistically significant with respect to all five structures: labrum, ligamentum teres, transverse acetabular ligament, pulvinar, and psoas tendon. The difference in visualization by magnetic resonance arthrography versus unenhanced magnetic resonance imaging was statistically significant with respect to the labrum and pulvinar. Magnetic resonance arthrography is indicated for assessing complete concentric reduction when it does not appear to be achieved by conventional arthrography, for confirming closed reduction immediately after manipulation, and potentially for preoperative planning for an open reduction.

Arthrography↗
PubMed1999

Segmental differences in vasodilatation due to basal NO release in in vivo cat pulmonary vessels.

This study was conducted to examine segmental differences in vasodilatation caused by the basal release of nitric oxide (NO) in the serially connected pulmonary vessels and to estimate the relative contributions of endothelial and neuronal NO synthase (NOS), and inducible NOS to the vasodilatation. Using an X-ray TV system on in vivo cat lungs, we measured internal diameter (ID) changes in resistance (100-400 microm ID), small conduit (600-1000 microm) and large conduit (1200-1700 microm) arteries, and veins of the same size. Non-selective NOS inhibitors, L-NAME (30-50 mg/kg i.v.) and L-NMMA (40-60 mg/kg i.v.), decreased the ID of all vessels studied, although their D-isomers had no effect. The decrease was larger in conduit arteries than in resistance arteries, with maximum response of small conduit arteries (25 +/- 2%), while venous segments displayed relatively uniform response (10-12%). L-Arginine completely abolished the ID decrease but hexamethonium bromide and phentolamine had no effect. Selective inhibitors of inducible NOS, L-canavanine (100 mg/kg i.v.) and S-methylisothiourea (10 mg/kg i.v.) did not affect any of the vessels. The data suggest that basal release of NO chiefly derived from endothelial NOS serves to dilate cat pulmonary arteries and veins, particularly small conduit arteries.

Angiography↗
PubMed1998

Neurological function after deep hypothermic circulatory arrest in the rat.

BACKGROUND: Integrated neurological function, behavior, and somatic recovery were studied in 35 rats undergoing 5 to 80 minutes of hypothermic circulatory arrest (HCA). METHODS AND RESULTS: A closed extracorporeal circulation system (ECC) consisting of a miniature oxygenator and heat exchanger, primed with 6 mL of asanguinous solution, was connected to a closed-chest rat with cannulae in the right atrium for venous drainage (ID = 1.7 mm) and in the ascending aorta for arterial return (ID = 1.0 mm). The rat was surface- and core-cooled until rectal temperature reached 18 degrees C, when ECC was stopped and cardioplegic solution delivered. After 5, 10, 20, 40 (each n = 5), and 80 minutes (n = 15) of HCA, the rat was reperfused, weaned from ECC, and followed with behavioral scoring, passive avoidance tasks, and cardiopulmonary exercise testing until euthanized for morphological study. Every rat resumed weight gain in the first week after HCA and regained preoperative exercise capacity by the fourth week. Only rats undergoing 80 minutes of HCA showed behavioral abnormalities such as stereotypy and incomplete righting reflex, which eventually disappeared in the fourth week. Learning ability was preserved in all except for rats after 80 min of HCA, who failed to acquire new memory to avoid electric stimuli (n = 10) up to 3 months after HCA, when pyramidal cells were partly replaced by astroglia in the cerebral cortex and CA1 sector of hippocampus. Nonetheless, old memory established before HCA was preserved even after 80 minutes of HCA and allowed rats (n = 5) to avoid electric stimuli. CONCLUSIONS: Homogeneity of animals, miniature ECC system, and an established testing system allowed evaluation of rats after HCA, which disclosed learning disability (functional disorder) and pyramidal cell loss (organic defect) after 80 minutes of HCA despite recovery of somatic function, behavior, and growth.

Animals↗
PubMed1998

Delayed diagnosis of a glenohumeral joint dislocation in a child with developmental delay.

Glenohumeral joint dislocations rarely occur in children. Those that have been reported have all been reduced in a closed fashion. With the exception of one, there have not been any comorbidities in the children that would have led to a delay in diagnosis. To the best of our knowledge, we report the first case of a child with a delayed diagnosis of an anterior dislocation of the glenohumeral joint that required an open reduction. In a child with other medical problems, especially developmental delay, who may have difficulty expressing his symptoms, early detection and intervention are crucial and may obviate the need for open reduction of the dislocated and painful glenohumeral joint.

Child↗
PubMed1998

Afferent reinnervation after lung transplantation in the rat.

Denervation at lung transplantation results in loss of cough reflex and attenuated local defense mechanisms, accounting for increased incidence and severity of infection after lung transplantation. We studied the presence or absence of spontaneous afferent reinnervation in rats at various intervals after orthotopic left pulmonary isografting (n = 52). Normal rats (n = 21) and rats undergoing left hilar stripping (n = 14) served as control subjects. Afferent reinnervation was tested physiologically by reflex bradycardia in response to intravenous infusion of capsaicin (30 microg/kg), an extract of paprika stimulating pulmonary C-fibers. Injection of capsaicin was repeated before and after right pulmonary artery occlusion to divert all pulmonary blood flow to the left lung or isograft. Whereas rats early after surgical denervation lost the reflex after right pulmonary artery occlusion, rats examined 8 months or longer after surgery showed potent reflex bradycardia in response to capsaicin, as did the control rats. Immunohistochemical staining for sensory neuron-specific substances, such as calcitonin gene-related peptide and substance P, were identified only in the right native lung and left pulmonary isografts 2 months or longer after transplantation. Fluorogold was found only in the ipsilateral nodose ganglion after left lung intrapleural injection of the neuron-specific tracer in rats 8 months or longer after denervation. These experiments provide physiological, morphologic, and neurologic evidence suggesting that afferent lung innervation, abolished early after transplantation, is spontaneously reestablished and functioning in the ipsilateral vagus nerve by 8 months after pulmonary isografting in the rat.

Animals↗
PubMed1997

Successful reversal of pulmonary hypertension in Eisenmenger complex.

We present a case of a 19-year old female with systemic pulmonary artery (PA) pressure due to a congenital ventricular septal defect (VSD) and atrial septal defect (ASD). She was pink at rest and cyanotic on exercise. Lung biopsy revealed grade IV pulmonary vascular changes. As a preliminary step PA was banded to increase right-to-left shunt and decrease aortic (Ao) saturation with consequent decrease in PA saturation. After one year, when she was no longer cyanotic, even on exercise, lung biopsy revealed total regression of pulmonary vascular changes. As a definitive procedure VSD and ASD were closed and PA was debanded. Cardiac catheterization one week postoperatively showed PA pressure to be 50% of systemic pressure. We postulate that reversal of pulmonary vascular changes were due to lowered PA saturation. We further believe that lower PA pressure could have contributed to this regression of pulmonary vascular changes. We performed the same procedure in six more patients with similar positive clinical response. This new concept brings renewed hope to many children who otherwise are candidates for heart lung transplantation.

Adult↗
PubMed1996

Factors affecting rhythm after the maze procedure for atrial fibrillation.

BACKGROUND: The maze procedure failed to abolish atrial fibrillation (AF) in 14% of patients with underlying organic cardiac lesions. Identification of contributing risk factors will improve results either by treatment of such factors or by avoidance of high-risk patients. METHODS AND RESULTS: We analyzed 192 consecutive patients with AF undergoing three variations of the maze procedure performed simultaneously with correction of valvular diseases (n = 165), congenital anomalies (n = 19), isolated AF (n = 7), and ischemic disease (n = 1). Twenty-six preoperative factors and two postoperative cardiac size parameters were analyzed by multivariate analyses between patients with successfully ablated AF (n = 165) and those who remained in AF (n = 27) after the maze procedure. Among all factors, postoperative left atrial dimension was the most potent in predisposing patients to persistent AF. Duration of AF left atrial dimension, and cardiothoracic ratio were identified as preoperative risk factors, whereas modifications of the maze procedure and pathogenesis and location of underlying disease failed to have a significant prognostic impact on rhythm after surgery. Individual risk analysis using the three preoperative variables revealed that left atrial size reduction to normalize its dimension played a pivotal role in determining rhythm after the maze procedure. CONCLUSIONS: Results favor earlier performance of the procedure before these risk factors develop, after which omission of the procedure or extensive left atrial plication may be appropriate. This requires further study.

Adolescent↗
PubMed1996

Risks and benefits of combined maze procedure for atrial fibrillation associated with organic heart disease.

OBJECTIVES: This study sought to identify the risks and benefits of adding the maze procedure in patients with atrial fibrillation (AF) undergoing operation for underlying organic cardiac disorders. BACKGROUND: Persistent AF often leaves patients symptomatic even after otherwise successful cardiac surgery. METHODS: Fifty-one patients undergoing valvular operation and the maze procedure (n = 43) or repair of congenital anomalies (n = 8) combined with the maze procedure were compared with 51 patients (control group) matched for underlying diseases and procedures except for the maze operation. Each group, including 31 patients with a concomitant tricuspid annuloplasty and 12 undergoing reoperation, were similar in age, duration of arrhythmia, degree of cardiomegaly and New York Heart Association functional class. RESULTS: Patients undergoing the maze procedure had longer cardiopulmonary bypass time (213 vs. 144 min, p < 0.0001), longer cardiac arrest (134 vs. 93 min, p < 0.0001) and greater blood loss with longer respiratory care (39 vs. 18 h p = 0.021) and intensive care unit stay but no mortality. No significant differences were found in catecholamine or transfusion requirements immediately after operation. Sustained AF was much less frequent in the maze group (12% at 1 year) than the control group (86%, p < 0.0001), with an average follow-up period of 32 months (range 25 to 42). Atrial contraction was documented in 41 (80%) and 40 (78%) patients for right and left ventricular filling, respectively, after the maze procedure, resulting in a significantly smaller cardiac size and improved functional capacity. Medication was discontinued in seven patients in the maze group compared with two in the control group. CONCLUSIONS: Improved restoration of atrial rhythm and contraction with combined maze operation appeared to justify the increased operative time and complexity and postoperative care.

Atrial Fibrillation↗
PubMed1996

Surgical stratification of patients with atrial fibrillation secondary to organic cardiac lesions.

BACKGROUND: While the maze procedure does not always eliminate atrial fibrillation (AF) secondary to organic cardiac lesions, concomitant performance of the procedure is associated with increased surgical complexity and potential risks. METHODS: To stratify the surgical approach for patients with AF secondary to underlying cardiac lesions, we analyzed 24 preoperative and perioperative variables in 115 consecutive patients with AF undergoing a modified maze procedure combined with valvular intervention (101), repair of congenital anomalies (13) and coronary revascularization (1). RESULTS: Patients who remained in AF (18) compared to patients with restored atrial rhythm (97), had a higher incidence of giant left atrium (56% vs 10%, P < 0.0001), larger cardiothoracic ratio (70 +/- 13 vs 62 +/- 8%, P = 0.001) and left atrial dimension (64 +/- 12 vs 55 +/- 12 mm, P = 0.004), a longer history of AF (13.7 +/- 6.8 vs 8.3 +/- 6.9 years, P = 0.003) and lower f-wave voltage (0.10 vs 0.15 mV, P = 0.004). Multivariate logistic regression analysis of 24 preoperative and perioperative variables identified the presence of giant left atrium, cardiothoracic ratio and age at operation as the significant risk factors predisposing patients to persistent postoperative AF. Retrospective estimation identified 73 (63.5%) patients with a high probability of atrial defibrillation (97.3%) and 42 (36.5%) patients with a high risk of failure (38.1%). Regardless of the preoperative risk analysis or the performance of left atrial plication, every patient with a postoperative left atrial dimension less than 40 mm or cardiothoracic ratio below 55% was successfully defibrillated. CONCLUSION: The results suggest performing the maze procedure before "risk factors" develop for patients with predicted maze-amenable AF. While omitting the maze procedure may be prudent for patients with suspected maze-refractory AF, the simultaneous reduction of left atrial size may offset the increased risk from preoperative size factors. A prospective study seems warranted to examine the effects of left atrial plication on postoperative rhythm.

Adult↗
PubMed1996

Right lung transplantation followed by left pneumonectomy in the rat.

OBJECTIVE: To develop a rodent lung transplant model which depends on graft function for survival, total microsutureless lung transplantation was carried out and followed by contralateral native pneumonectomy in the rat. METHODS: Total non-microsuture right lung transplantation was undertaken using a cuff technique with anastomotic areas twice as big as those for the left lung transplantation. Inbred rats received either right (n = 10) or left lung isograft (n = 10) with non-microsuture techniques and underwent contralateral native pneumonectomy 2 weeks later to test the function of the grafted lung. RESULTS: While none of the left lung recipients could be disconnected from the respirator after right pneumonectomy, eight of ten right lung recipients tolerated left pneumonectomy, increased body weight and regained exercise capacity (oxygen uptake 49 +/- 4 ml/kg per min) comparable to that of control rats undergoing right hilar stripping and left pneumonectomy. CONCLUSIONS: The results suggest that the grafted right lung, but not the left lung, allows survival, growth and exercise of the recipient. Right lung transplantation followed by native left pneumonectomy may serve as a physiologic model of lung transplantation in the rat.

Animals↗
PubMed1996

Inhaled nitric oxide: diameter response patterns in feline small pulmonary arteries and veins.

Using an X-ray television system on the in vivo cat lung, we directly measured internal diameter (ID) changes in the small pulmonary arteries and veins (100-1,100 microns ID) in response to 5, 15, and 40 ppm nitric oxide (NO) inhalations. We also measured to what extent 40 ppm NO inhalation can attenuate large ID constrictions at the different serial segments of the small vessels due to unilobar anoxic (0% O2) exposure. Under normoxic conditions, 5-40 ppm NO inhalations significantly increased the ID of both arteries and veins less than approximately 900 microns dose dependently but caused no significant, or only slight, ID increases in the vessels larger than this, if any at all. The ID increase in the serially connected arteries was nonuniform (4-18, 8-28, and 7-35% with 5, 15, and 40 ppm NO inhalations, respectively), whereas that for the veins was relatively uniform (4-9, 6-17, and 7-18% with 5, 15, and 40 ppm NO, respectively). The maximum ID increase occurred in the 200- to 500- and 200- to 700-microns arteries in response to 5-15 and 40 ppm NO, respectively. Unilobar anoxic exposure significantly decreased the ID of the 100- to 700-microns arteries and veins, but not the ID of the other-sized vessels. The ID decrease in the serially connected arteries was nonuniform (13-29%) but relatively uniform in the veins (8-12%). The maximum ID decrease occurred in the 200- to 300-microns arteries. However, adding 40 ppm NO to the lobe completely eradicated the ID decreases at all segments of the arteries and veins and, instead, caused significant ID increase (11-21%) in the arteries and (10-12%) in the veins. The data indicate that, according to dosage, 5-40 ppm NO inhalations cause selective dilation of approximately 100- to 900-microns pulmonary arteries and veins, particularly the 200- to 700-microns arteries. During anoxic exposure, the vasodilator effect of NO is preserved and can completely reverse the marked pulmonary vasoconstriction.

Administration, Inhalation↗
PubMed1995

Modified maze procedure for patients with atrial fibrillation undergoing simultaneous open heart surgery.

BACKGROUND: Persistent atrial fibrillation (AF) leaves patients symptomatic and at increased risk of thromboembolism even after otherwise successful cardiac surgery. METHODS AND RESULTS: To treat AF secondary to cardiac lesions requiring surgery, we combined a modified maze procedure in 101 patients simultaneously undergoing valvular procedures (87), repair of congenital anomalies (12), and other procedures (2), including 24 repeat operations. Duration of AF varied from 0.1 to 30 years (average +/- SD, 8.8 +/- 7.0 years); the f-wave voltage ranged from 0 to 0.45 mV (0.15 +/- 0.09 mV); and cardiothoracic ratio varied from 40% to 99% (63 +/- 9%). Aortic cross-clamp time varied from 75 to 229 minutes (138 +/- 31 minutes), with bypass time ranging from 119 to 326 minutes (217 +/- 42 minutes). There were two early deaths (2%), no late deaths, and one episode of transient neurological ischemic attack in follow-up ranging from 1.0 to 3.1 years, for a total of 190 patient-years. Postoperative rhythms were sinus in 83 patients (82%), junctional in 4 (4%), and persistent AF in 14 (14%), each of whom had mitral valve disease. Patients with other underlying pathology had complete recovery of atrial rhythm. A normal-sized A wave was detected in 88% for transtricuspid flow and in 73% for transmitral flow, suggesting concomitant recovery of atrial contraction. Among 36 patients without mechanical valves, 30 (83%) with atrial rhythm and contraction have been taken off anticoagulation therapy, including 10 who are free of all medication. CONCLUSIONS: The results suggest that the combined approach is safe, effective, and indicated in patients who are judged capable of tolerating the procedure and likely to regain atrial rhythm.

Aged↗
PubMed1995

Changes in efferent pulmonary sympathetic nerve activity during systemic hypoxia in anesthetized cats.

Changes in efferent sympathetic nerve activity to the pulmonary vessels during systemic hypoxia have yet to be elucidated. The purpose of this study was to determine the pulmonary sympathetic nerve activity (PSNA) changes in response to acute systemic hypoxia before and after sinoaortic denervation plus vagotomy in anesthetized cats. The denervation was performed to estimate the central nervous system-mediated peripheral chemoreceptor- and baroreceptor-independent PSNA change. PSNA was recorded from the central end of the cut nerve bundle, which was isolated from the lobar artery supplying the diaphragmatic lobe. Renal sympathetic nerve activity (RSNA) and systemic and pulmonary arterial pressures were also measured simultaneously. The animals were submitted to approximately 3-min periods of graded hypoxia (16, 12, 8, 5, and 3% O2 inhalations). PSNA did not change from normoxia down to an arterial O2 partial pressure (PaO2) of approximately 45 Torr (with 12-21% O2 inhalations). Below this level, PSNA began to increase, and markedly so (approximately 2.5-fold) at a PaO2 of approximately 15 Torr (with 3% O2). The hypoxic PSNA increase was significantly larger than that for RSNA, with a PaO2 of less than approximately 30 Torr (with 3-8% O2). Particularly at a PaO2 of approximately 15 Torr, the magnitude of the PSNA increase was two times greater than that for RSNA. After denervation, the hypoxic PSNA increase was significantly attenuated at a PaO2 of approximately 25 to approximately 45 Torr (with 5-12% O2), but the attenuation was very small; therefore most of the PSNA increase persisted. The hypoxic RSNA increase, in contrast, was mostly abolished after denervation. The data indicate that the neural reflex effect of systemic hypoxia on PSNA is significantly greater than that on RSNA and suggest that the hypoxic PSNA increase is mostly mediated by central mechanisms, whereas that for RSNA is chiefly caused by peripheral chemoreceptors.

Animals↗