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Biomedical subjects

Y Arakaki

Publications and source records attributed to Y Arakaki.

At least 19 recordsLinked to original sources
PubMed2005

Prognosis of HTLV-I-positive renal transplant recipients.

HTLV-I is the pathogen that causes adult T-cell leukemia (ATL) and HTLV-I-associated myelopathy (HAM). The rate of disease development is low and the latency time is a few decades. However, the possible influence of immunosuppression on this disease development is unclear. The purpose of this study was to investigate the risk of development of ATL and HAM among the large number of HTLV-I-positive renal transplant recipients in western Japan. In principle immunosuppressive drugs have the possibilities to accelerate ATL development but are thought to suppress HAM development. Of 120 renal transplant recipients, 10 HTLV-I-positive recipients were reviewed, none of whom developed ATL or HAM. There are 11,896 dialysis patients in Japan and 300 dialysis patients in Okinawa who are registered with the JOTN for cadaveric renal transplant. The numbers of HTLV-I-positive patients in these groups were 97 (0.82%) and 26 (8.67%), respectively. These numbers are thought to be sufficient for an HTLV-I-positive recipient pool for HTLV-I-positive donors. Ten cases of ATL development and two of HAM development have been previously reported. Because of low number of ATL development, renal transplantation does not appear to be a contraindication for HTLV-I-positive chronic renal failure patients. In other words, kidneys from HTLV-I carriers, which include cadaveric donors, could be used for HTLV-I-positive recipients.

Adult↗
PubMed2003

Recent speciation in the Indo-West Pacific: rapid evolution of gamete recognition and sperm morphology in cryptic species of sea urchin.

The rich species diversity of the marine Indo-West Pacific (IWP) has been explained largely on the basis of historical observation of large-scale diversity gradients. Careful study of divergence among closely related species can reveal important new information about the pace and mechanisms of their formation, and can illuminate the genesis of biogeographic patterns. Young species inhabiting the IWP include urchins of the genus Echinometra, which diverged over the past 1-5 Myr. Here, we report the most recent divergence of two cryptic species of Echinometra inhabiting this region. Mitochondrial cytochrome oxidase 1 (CO1) sequence data show that in Echinometra oblonga, species-level divergence in sperm morphology, gamete recognition proteins and gamete compatibility arose between central and western Pacific populations in the past 250 000 years. Divergence in sperm attachment proteins suggests rapid evolution of the fertilization system. Divergence of sperm morphology may be a common feature of free-spawning animals, and offers opportunities to simultaneously understand genetic divergence, changes in protein expression patterns and morphological evolution in traits directly related to reproductive isolation.

Animals↗
PubMed2003

Clinical evaluation of combined endoscopic variceal ligation and sclerotherapy of gastric varices in liver cirrhosis.

BACKGROUND AND STUDY AIMS: Endoscopic injection sclerotherapy (EIS) using cyanoacrylate and balloon-occluded retrograde transvenous obliteration (B-RTO) are the main procedures used to treat gastric varices. However, neither technique is free of problems. EIS for gastric varices may cause embolism in other organs; B-RTO requires a gastrorenal shunt and may aggravate esophageal varices. We have developed a combined form of endoscopic therapy involving band ligation and sclerotherapy which is an effective and safe procedure for treating gastric varices. PATIENTS AND METHODS: Fifty-six patients with gastric varices and liver cirrhosis were treated at Almeida Memorial Hospital from June 1997 to May 2002 using the combined procedure. Each gastric varix was tightly ligated with O-rings, and 1 % polidocanol was injected into the submucosa around the ligated varix. If necessary, additional sclerotherapy was carried out after the initial treatment. RESULTS: The rate of hemostasis for variceal bleeding was 100 %, and no critical complications were noted. Complete disappearance of the gastric varices was observed endoscopically in all cases. Computed tomography showed that collateral vessels outside the gastric wall were not occluded by the treatment. Endoscopic follow-up examinations were carried out, and gastric varices recurred in seven patients (12.5 %). Only two of the patients (3.6 %) had a small amount of oozing bleeding. Additional endoscopic variceal ligation (EVL) and/or EIS were performed in these seven cases, and none of the patients died as a result of a bleeding gastric varix. CONCLUSIONS: The combined procedure was easily performed immediately after endoscopic examination, and required no special apparatus. It was found to be a safe and effective method of treating gastric varices.

Adult↗
PubMed2001

Coagulation profile, hepatic function, and hemodynamics following Fontan-type operations.

We analyzed retrospectively the relationship between coagulation profile, and either hepatic function or hemodynamics, in patients who had undergone a Fontan-type procedure, comparing them, first, with a control group of 12 patients without significant hemodynamic abnormality, and, second, with a group of 14 patients who had not undergone a Fontan procedure, but whose mean right atrial pressure exceeded 8 mmHg. Follow-up catheterization had been performed in all 30 patients submitted to the Fontan-type operation. Prothrombin time, and factor XIII, were significantly lower in those who had undergone the Fontan procedure than in the other groups. Those submitted to the Fontan operation also had lower levels of protein C than controls, and their levels of plasminogen were lower than the patients with high right atrial pressure. Both aspartate aminotransferase and alanine aminotransferase were higher in those undergoing the Fontan procedure than in the other groups, while gamma-glutamyltranspeptidase in these patients was higher than in the control group. Mean right atrial pressure was highest in those undergoing the Fontan procedure, while cardiac index was lowest. Prothrombin time was correlated to some extent with aspartate aminotransferase, mean right atrial pressure, and cardiac index. Protein C correlated with both aspartate aminotransferase and mean right atrial pressure, while factor XIII correlated with alanine aminotransferase, mean right atrial pressure, and cardiac index. Aspartate aminotransferase, alanine aminotransferase, and gamma-glutamyltranspeptidase, parameters of hepatic function, correlated significantly with mean right atrial pressure. In those who had undergone the Fontan procedure, decreased synthesis of pro-and anti-coagulant factors is a risk factor for both thrombosis and bleeding. Abnormal hemodynamics, in the absence of a right sided pumping chamber, may predispose to subclinical hepatic dysfunction, leading to selective disturbances of protein synthesis.

Adolescent↗
PubMed2001

Incidence of spontaneous closure of outlet ventricular septal defect.

The present study examined the Doppler echocardiograms of 742 patients with an outlet ventricular septal defect (VSD) who were seen at the National Cardiovascular Center from 1987 to 1999. Of these, 450 patients were followed for longer than 1 year; 161 of these 450 were younger than 12 months when first examined. During follow-up, Doppler echocardiographic examination was repeated at least once a year. The medical charts of these patients were reviewed. Doppler echocardiographic findings were analysed in patients whose defect closed spontaneously:spontaneous closure at the age of 1-25 years was identified in 17 (3.8%) of 450 patients who were followed for longer than 1 year, and 7 (4.3%) of the 161 patients who were younger than 12 months at the first examination. All closed VSDs were originally smaller than 4mm. Although 5 cases of 17 developed trivial deformity of the right coronary cusp, suggesting a prolapse, this did not progress. Of these 5, trivial aortic regurgitation (AR) was detected in one patient, while another patient in the group of 17 developed trivial AR without any deformity of the right coronary cusp. Aortic regurgitation was not progressive in either patient. An outlet VSD closes spontaneously in a small percentage of patients without developing progressive AR.

Adolescent↗
PubMed2001

Imbalance of cusp width and aortic regurgitation associated with aortic cusp prolapse in ventricular septal defect.

The Doppler echocardiograms of the aortic valve and associated aortic regurgitation (AR) were reviewed in 72 patients with a ventricular septal defect (VSD). Group I comprised 13 patients without any deformity of the aortic cusp for > or = 10 years, group 2 included 35 patients who did not develop AR for > or = 10 years after right coronary cusp prolapse (RCCP) was first detected, group 3 comprised 11 patients with RCCP and AR in whom the AR remained subclinical for > or = 10 years, and group 4 was 13 patients who underwent surgical treatment because of moderate to severe AR. The cusp imbalance index [width of right (R) or non- (N) coronary cusp/width of left coronary cusp (L)] was compared among the 4 groups. R/L or N/L was larger in group 4 than in groups 1-3; R/L exceeded 1.30 in all the patients in group 4, whereas it was less than 1.30 in all the atients in groups 1-3. Two patients in group 4 with non-coronary cusp prolapse had an N/L greater than 1.50. No other patients in any group had an N/L larger than 1.20. An imbalance of cusp width may predict possible progressive deterioration of AR.

Adolescent↗
PubMed2000

Abnormal cardiac autonomic nervous activity after right ventricular outflow tract reconstruction.

BACKGROUND: There are few studies of cardiac autonomic nervous activity (CANA) in patients with congenital heart disease. Methods and Results-We evaluated CANA in 54 patients after closure of an atrial/ventricular septal defect (group A), 54 patients after successful right ventricular outflow tract reconstruction (RVOTR) (group B1), 35 RVOTR patients with residual stenosis (group B2), and 47 controls. Cardiac parasympathetic nervous activity (PSNA) was estimated by heart rate (HR) change after cholinergic blockade, HR variability, and arterial baroreflex sensitivity (BRS). Cardiac sympathetic nervous activity was estimated by the heart-to-mediastinum (123)I-metaiodobenzylguanidine activity ratio (H/M) and HR increase after isoproterenol infusion (ss). HR response (DeltaHR) and peak oxygen uptake (VO(2)) were measured by exercise test. There was no difference in ss among study groups. Group A exhibited mildly impaired PSNA, which recovered 1 year after surgery, and no change in H/M. Impaired PSNA and low H/M were found in groups B1 and B2 compared with controls (P<0.001), although the PSNA tended to recover 1 year after re-RVOTR. In group B1, PSNA and ss were related to DeltaHR, and BRS correlated inversely with the number of surgical procedures and age at RVOTR and positively correlated with the follow-up period, whereas DeltaHR correlated with peak VO(2) (P<0.01 to 0.001). CONCLUSIONS: After RVOTR, postsynaptic ss-sensitivity is maintained and is important in DeltaHR during exercise, as is PSNA, although ventricular sympathetic denervation is common. Impaired PSNA immediately after RVOTR improves with improved DeltaHR and results in future amelioration of aerobic capacity, whereas ventricular sympathetic reinnervation is uncertain.

Adolescent↗
PubMed2000

Evolution of aortic regurgitation following simple patch closure of doubly committed subarterial ventricular septal defect.

We reviewed the Doppler echocardiographic findings of the aortic valve and associated aortic regurgitation (AR) in 55 patients who underwent patch closure of doubly committed subarterial ventricular septal defect (VSD). The maximal diameter of the VSD measured > or = 5 mm, whereas the postoperative follow-up interval was > or = 5 years. Twenty-three patients underwent closure before they developed aortic cusp prolapse or AR (group A). In 15 patients the VSD was closed when aortic cusp prolapse was recognized, but AR was absent (group B). Aortic cusp prolapse with AR was detected before closure in a further 15 patients (group C). Of 8 patients with no AR before closure, AR was detected during follow-up in 6 group A and in 2 group B patients. In group C, AR resolved after surgery in 4 patients, whereas AR grade improved in a further 8 patients and remained unchanged in 3. Although residual AR was more frequent in patients with aortic cusp prolapse and AR before closure, it was silent and asymptomatic.

Adolescent↗
PubMed2000

Ventilatory response to exercise in patients with major aortopulmonary collateral arteries after definitive surgery.

Patients with pulmonary atresia and major aortopulmonary collateral arteries (MAPCAs) may be at risk for both ventilatory impairment and abnormal pulmonary circulation after definitive surgery. We measured the ventilatory response to exercise in 16 patients with MAPCAs after definitive surgery (group A) and compared the results with those in 16 patients with tetralogy of Fallot with pulmonary atresia and without MAPCAs after definitive operation (group B), with 24 patients with tetralogy of Fallot after one-stage repair without previous palliation (group C), and with 48 healthy subjects (group D). Pulmonary function and treadmill exercise tests were performed. Arterial blood gases were also analyzed and the dead space to tidal volume ratio calculated. In group A, the vital capacity, diffusion capacity, and peak oxygen uptake were lowest (p <0.001), whereas the ventilatory equivalent for carbon dioxide was highest and its value at peak exercise correlated with age at time of surgery (r = 0.73, p <0.002). The arterial oxygen tension decreased progressively in group A and its value at peak exercise inversely correlated with the mean pulmonary artery pressure in all patients (r = -0.75, p <0.001). The arterial carbon dioxide tension decreased significantly at peak exercise in controls but showed no change in group A. The dead space to tidal volume ratio decreased during exercise in patients without MAPCAs and in controls but increased in group A, and the dead space to tidal volume ratio at peak exercise was inversely correlated with vital capacity in all patients (r = -0.77, p <0.001). Diffusion capacity independently predicted arterial carbon dioxide tension and dead space ventilation during exercise. Marked restrictive ventilatory impairment with low diffusion capacity along with a pulmonary obstructive change contributed to the abnormal pulmonary gas exchange during exercise in group A. Earlier repair of MAPCAs may prevent the progression of the impaired ventilatory response to exercise in these patients.

Adolescent↗
PubMed2000

Unilateral pedal lymphography in patients with filarial chyluria.

OBJECTIVE: To evaluate the usefulness of unilateral pedal lymphography in patients with filarial chyluria. PATIENTS AND METHODS: Of 114 patients with filarial chyluria, all underwent lymphography (unilateral pedal in 106) and 55 underwent selective ureteric sampling for chyle. RESULTS: Unilateral pedal lymphography in the 106 patients detected lymphaticorenal fistulae (LRF) in 104 (98%). Lymphatic crossover was seen in all 106 patients, from the second sacral segment to the first lumbar segment. The most frequent crossover site was at the L5 level (87%). There was complete correlation between the side of LRF and the side of chyluria as assessed by selective ureteric sampling. CONCLUSION: Unilateral pedal lymphography can detect LRF via lymphatic crossover even when it is on the opposite side from that injected with contrast agent. The advantages of unilateral lymphography over bilateral procedures are that it is easy to identify crossover channels, and the discomfort for the patient is reduced because there are fewer incisions and it is quicker. Unilateral lymphography is recommended as the initial method when lymphography is indicated in filarial chyluria.

Adult↗
PubMed2000

Heart rate recovery after exercise and cardiac autonomic nervous activity in children.

To investigate the difference in heart rate (HR) recovery after exercise between children and young adults, we administered a constant load of light exercise intensity and progressive treadmill exercise tests to nine children (aged 9 to 12 y, group A) and eight young adults (six male and two female, aged 17 to 21 y, group B) who had a history of Kawasaki disease without significant coronary arterial lesions. HR after both exercise protocols was analyzed. The low-frequency (LF) and high-frequency (HF) components of HR variability were measured, and LF/HF was calculated (log LF, log HF, log L/H). Arterial baroreflex sensitivity was assessed by the phenylephrine method. There were no differences between groups A and B in resting HR, peak HR, peak oxygen uptake, and decreases in systolic blood pressure during the recovery period. HR 1 and 2 min after peak exercise and 1 min after constant-load exercise was significantly lower in group A than in group B (p < 0.05), and the changes in HR from peak values after both exercise tests were also greater in group A than in group B (p < 0.05-0.01). Although no difference in arterial baroreflex sensitivity was observed, log HF was significantly higher in group A than in group B (p < 0.01), and log L/H was significantly lower in group A than in group B (p < 0.05). The value of log HF correlated inversely with the decrease in HR immediately after both exercise protocols (p < 0.05-0.01). Although log L/H correlated with the decrease in HR after peak exercise (p < 0.05-0.0005), the early decline in HR after constant-load exercise did not correlate with log L/H. Arterial baroreflex sensitivity did not correlate with the decrease in HR at any recovery time. These data suggest that the early phase of HR recovery after light to severe exercise is influenced by the cardiac parasympathetic nervous activity at rest and that the greater central cholinergic modulation of HR in children than in young adults may be responsible in part for children's faster HR recovery after exercise.

Adolescent↗
PubMed1999

Comparison of the right and left ventricle as a systemic ventricle during exercise in patients with congenital heart disease.

BACKGROUND: Few studies have investigated the clinical advantages of surgical correction with the morphologic left ventricle (MLV) instead of the morphologic right ventricle as a systemic ventricle (SV) in patients with congenital heart disease. METHODS: Twenty-four healthy control subjects (group A1), 6 patients with isolated congenitally corrected transposition of the great arteries (TGA) (group A2), 16 patients with TGA who had undergone an arterial switch operation (group B1), 18 patients with TGA who had undergone a venous switch operation (group B2), 9 patients with atrioventricular and ventriculoarterial discordance who had undergone a double switch operation (group C1), and 6 patients with atrioventricular and ventriculoarterial discordance who had undergone a conventional external conduit operation from the MLV to the pulmonary artery (group C2), performed treadmill exercise testing. Their heart rate (HR), oxygen uptake (VO2), and oxygen pulse (O2 pulse), which reflects individual stroke volume, were measured, and contractile function was assessed by echocardiography. RESULTS: The peak HR for the patients after a definitive operation were significantly lower than that in group A1 and was correlated with peak VO2 (r =.67, P <.0001). The peak VO2 and peak O2 pulse for the groups A2 and B2 were significantly lower than those for the groups A1 and B1, respectively. The peak O2 pulse data were strongly correlated with those of peak VO 2 (r = 0.91, P <.0001). The left ventricular ejection fraction was significantly lower in groups B1 and C1 than in group A1 and was correlated with peak VO 2 (r =.50, P <.01). No significant differences in VO2, HR, and O 2 pulse at peak exercise were observed between groups C1 and C2. CONCLUSIONS: Chronotropic incompetence and an impaired response of the stroke volume of the MRV during exercise are partly responsible for the reduced exercise capacity in groups A2 and B2 compared with groups with the MLV as an SV, and the SV function at rest is also related to exercise capacity. Superiority of the double-switch operation compared with the conventional conduit operation was not observed. A longer-term follow-up is necessary before the advantages of these 2 operations can be compared.

Adolescent↗
PubMed1999

Ventilatory response and arterial blood gases during exercise in children.

To investigate the difference in ventilatory response to exercise between children and young adults, we administered a treadmill progressive exercise test to seven boys (aged 8 to 11 y [group A]) and six male young adults (aged 14 to 21 y [group B]), who had a history of Kawasaki disease without significant coronary arterial lesions, and analyzed their arterial blood gases. There was no significant difference in arterial PO2 or the end-tidal to arterial oxygen tension difference during exercise between groups A and B. The arterial PCO2 (PaCO2) at the ventilatory anaerobic threshold and at peak exercise was significantly lower in group A than in group B (p < 0.05). The arterial to end-tidal carbon dioxide tension difference at peak exercise was significantly greater in group B than in group A (p < 0.05), whereas there was no significant difference at rest or at the ventilatory anaerobic threshold level. The arterial to end-tidal carbon dioxide tension difference at peak exercise was correlated with tidal volume (p < 0.01) and carbon dioxide production (p < 0.05) at peak exercise in all subjects. Although improvement in the physiologic dead space/tidal volume ratio during exercise was smaller in group A than in group B, there was no significant difference in total alveolar ventilation during exercise. However, the total carbon dioxide production during exercise was significantly smaller in group A than in group B. These data suggest that PaCO2 during exercise is better estimated by end-tidal carbon dioxide tension in children than in young adults, that there is a significant difference in change of the PaCO2 during exercise between children and young adults, and that the decrease in PaCO2 in children is related to the mismatch between well-maintained alveolar ventilation and immature metabolic development in the working muscles during moderate-to-severe exercise.

Adolescent↗
PubMed1998

Cardiorespiratory response during exercise in patients with cyanotic congenital heart disease with and without a Fontan operation and in patients with congestive heart failure.

To clarify the different cardiorespiratory response to exercise in patients with congenital heart disease and patients with chronic congestive heart failure, we investigated the effect of a progressive exercise test in 30 patients aged 10 to 24 years, including 9 patients with cyanotic congenital heart disease (group A), 13 patients who had undergone a Fontan operation (group B), and 8 patients with reduced left ventricular function (group C), and 18 healthy controls (group D). There was no difference in peak oxygen uptake among patient groups and all group A, B, and C values were lower than those in group D (P<0.001). Although peak heart rate was lower in patient groups than in group D, heart rate at a given exercise intensity was highest in group C. The oxygen pulse (oxygen uptake divided by heart rate=stroke volume x arterial venous oxygen difference), as an indicator of stroke volume, was lower in patients groups, especially in group C, than in group D. There was no difference in tidal volume between groups A and D, but the respiratory rates at any given exercise intensity were higher in group A than in the other patient groups, thus minute ventilation and the ventilatory equivalent were highest in group A. The increased respiratory rate and low tidal volume in group C resulted in rapid and shallow respiration. There was no difference in exertional symptoms at peak exercise among the groups. In addition to impaired responses of stroke volume during exercise in patients with reduced exercise capacity, there was little limitation of increase in ventilation in group B and excessive ventilation in group A. The present results suggest that relationship between ventilatory and cardiac responses during exercise in patients with cyanotic congenital heart disease with and without a Fontan operation is different from the relationship in patients with chronic congestive heart failure; however, these pathological differences did not influence exertional symptoms.

Adolescent↗
PubMed1997

Cardiorespiratory responses to exercise after repair of the univentricular heart.

The purpose of this study is to evaluate cardiorespiratory responses to exercise in patients with univentricular heart according to the type of repair used. Forty-three patients with univentricular heart were divided into three groups: 15 preoperative patients (group A), 18 who had Fontan repair (group B) and 10 who had ventricular septation (group C). Group C was further divided into two subgroups, 7 with normal atrioventricular valve function (group C1) and 3 with atrioventricular valve regurgitation (group C2). Cardiorespiratory variables were determined after performance of cardiopulmonary exercise testing. One-hundred-and-twenty-five healthy subjects, age 5-26 years, served as controls. Oxygen uptake in group C1 at both ventilatory threshold and peak exercise was highest in all groups of univentricular heart (P < 0.05), while peak oxygen uptake in group C1 was significantly lower vs controls (P < 0.001), and that in group B was significantly higher than that for group A. Although chronotropic incompetence was noted in all groups of univentricular heart, marked improvements in both the relationship between heart rate and oxygen uptake and in the ventilatory efficiency were observed after definitive repair. While ventilatory efficiency was still impaired in group B, there was no significant difference between that in group C1 and the control group. When patients with univentricular heart of the left ventricular type (Van Praagh's type A single ventricle) were analyzed separately, superior cardiorespiratory response after ventricular septation was also found. In view of these findings, the ventricular septation procedure is preferred to the Fontan method in patients with univentricular heart when morphological conditions are suitable for this procedure so as not to make residual complications, such as significant atrioventricular valve regurgitation.

Adolescent↗
PubMed1997

Prophylactic effect of dietary glutamine supplementation on interleukin 8 and tumour necrosis factor alpha production in trinitrobenzene sulphonic acid induced colitis.

BACKGROUND: It is well established that glutamine supplemented elemental diets result in less severe intestinal damage in experimental colitis. However, few studies have examined the mode of action of glutamine in reducing intestinal damage. AIMS: To examine the effects of glutamine supplemented elemental diets on the potent inflammatory cytokines interleukin 8 (IL-8) and tumour necrosis factor alpha (TNF-alpha) in trinitrobenzene sulphonic acid (TNBS) induced colitis which presents with both acute and chronic features of ulcerative colitis. METHODS: Sprague-Dawley rats were randomised into three dietary groups and fed 20% casein (controls), or 20% casein supplemented with either 2% glutamine (2% Gln) or 4% glutamine (4% Gln). After two weeks they received intracolonic TNBS to induce colitis. RESULTS: Both Gln groups of rats gained more weight than the control group (p < 0.05) which had progressive weight loss. Colon weight, macroscopic, and microscopic damage scores for the Gln groups were lower than in the control group (p < 0.05). IL-8 and TNF-alpha concentrations in inflamed colonic tissues were lower in the Gln groups than in the control group (p < 0.05), and correlated well with disease severity. Bacterial translocation was lower both in incidence (p < 0.05) and in the number of colony forming units (p < 0.05) for the Gln groups, than in the control group. With respect to all indices studied, the 4% Gln group performed better than did the 2% Gln group. CONCLUSION: Prophylactic glutamine supplementation modulates the inflammatory activities of IL-8 and TNF-alpha in TNBS induced colitis.

Analysis of Variance↗
PubMed1997

Alveolar-arterial gas tension differences during progressive exercise in patients after the Fontan operation.

We investigated alveolar-arterial gas tension differences as a measurement of ventilatory impairment during exercise in patients who had undergone the Fontan operation. The ventilatory response to exercise in 13 operated patients was compared with that of 11 control subjects. The difference between end-tidal and arterial oxygen tension (P(ET-a)DO2) and between arterial and end-tidal carbon dioxide tension (P(a-ET)DCO2) as well as the physiologic dead space-tidal volume ratio were calculated during progressive treadmill exercise testing. In the Fontan group, P(ET-a)DO2 and P(a-ET)DCO2 were significantly higher than in control subjects and increased in parallel during the study period. The physiologic dead space-tidal volume ratio was higher in the Fontan group than in the control group, and the difference in these ratios between the values obtained using end-tidal carbon dioxide tension and those using arterial carbon dioxide tension correlated well with P(a-ET)DCO2 (r = -0.79 to -0.98, p < 0.001). The physiologic dead space-tidal volume ratio during exercise was significantly higher in patients with low exercise capacities than in those with high exercise capacities (p < 0.05). The alveolar-arterial gas tension differences during exercise were greater in Fontan patients than in control subjects. We conclude that the size of the physiologic dead space can be evaluated from measurements of arterial carbon dioxide tension and is correlated with impaired exercise capacity after the Fontan operation.

Adolescent↗