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Biomedical subjects

Makoto Nakazawa

Publications and source records attributed to Makoto Nakazawa.

At least 19 recordsLinked to original sources
PubMed2004

Skeletal muscle hemodynamics and endothelial function in patients after Fontan operation.

To elucidate the relation between exercise capacity and peripheral hemodynamics in patients after the Fontan operation, near-infrared spectroscopy was performed on the vastus lateralis muscle, and flow-mediated vasodilation of the brachial and posterior tibial arteries was done with high-resolution ultrasonography. In Fontan patients, diminished exercise capacity was related to a reduced blood flow supply and an attenuated post-exercise oxygen resaturation of the working skeletal muscle, which also was related to impaired endothelium-dependent vasodilation.

Adolescent↗
PubMed2004

Left ventricular diastolic dysfunction in Ebstein's anomaly.

This study was performed to evaluate left ventricular (LV) diastolic function in patients with Ebstein's anomaly using Doppler echocardiography. We found that LV abnormal relaxation in this anomaly cannot be explained by right ventricular volume overload alone. Furthermore, LV diastolic dysfunction persists even after intracardiac repair.

Cardiac Catheterization↗
PubMed2004

Arrhythmias late after repair of tetralogy of fallot: a Japanese Multicenter Study.

BACKGROUND: Arrhythmia is a major late complication in adults with repaired tetralogy of Fallot, although a large-scale study has not been carried out in Japan. METHODS AND RESULTS: A nationwide multicenter study with 512 operative survivors was performed. Actuarial survival rate at 30 years (maximum follow-up) was 98.4%. Fifty-four patients (10.5%) had clinically important arrhythmias, including 23 patients with bradycardia caused by sick sinus syndrome or atrioventricular block (AVB). A patient with complete AVB (CAVB) without pacemaker implantation (PMI) died later. Two patients had sustained ventricular tachycardia (VT) and syncope was reported in 18 patients with ventricular arrhythmias (VA). Atrial tachyarrhythmias were observed in 13 patients. Older age at operation was a risk factor for atrial fibrillation/flutter, longer postoperative survival duration for VA, and QRS duration >120 ms for VT. Perimembranous ventricular septal defect was related to CAVB. Right ventricular outflow patch was not a risk factor. Importantly, 60% of the subjects had QRS duration <120 ms. CONCLUSION: The prevalence of serious arrhythmias is low in Japanese TOF patients as compared with the results from Western countries. CAVB without PMI and VT are the major risk factors for late morbidity and mortality. The excellent result could be related to the narrow QRS after surgery.

Adolescent↗
PubMed2003

Role of TBX1 in human del22q11.2 syndrome.

BACKGROUND: Del22q11.2 syndrome is the most frequent known chromosomal microdeletion syndrome, with an incidence of 1 in 4000-5000 livebirths. It is characterised by a 3-Mb deletion on chromosome 22q11.2, cardiac abnormalities, T-cell deficits, cleft palate facial anomalies, and hypocalcaemia. At least 30 genes have been mapped to the deleted region. However, the association of these genes with the cause of this syndrome is not clearly understood. METHODS: To test for the chromosomal deletion at 22q11.2, we did fluorescence in-situ hybridisation analysis with ten probes on 22q11.2 in 235 unrelated patients with clinically diagnosed del22q11.2 syndrome. To investigate mutations in the coding sequence of TBX1, we also did genetic analysis in 13 patients from ten families who have the 22q11.2 syndrome phenotype but no detectable deletion of 22q11.2. FINDINGS: 96% (225 of 235) of patients had a defined 1.5-3-Mb deletion at 22q11.2. We identified three mutations of TBX1 in two unrelated patients without the 22q11.2 deletion-one with sporadic conotruncal anomaly face syndrome/velocardiofacial syndrome and one with sporadic DiGeorge's syndrome-and in three patients from a family with conotruncal anomaly face syndrome/velocardiofacial syndrome. We did not record these three mutations in 555 healthy controls (1110 chromosomes; p<0.0001). INTERPRETATION: Our results suggest that the TBX1 mutation is responsible for five major phenotypes in del22q11.2 syndrome. Therefore, we conclude that TBX1 is a major genetic determinant of the del22q11.2 syndrome.

Abnormalities, Multiple↗
PubMed2003

Developmental changes in ventricular diastolic function correlate with changes in ventricular myoarchitecture in normal mouse embryos.

Both genetic and epigenetic factors, such as abnormal hemodynamics, affect cardiac morphogenesis and the pathogenesis of congenital heart disease. Diastolic function is an important determinant of cardiac function, and tools for evaluating diastolic function in the embryo would be very valuable for assessment of cardiac performance. Using histological measurements of ventricular myoarchitecture, Doppler assessment of ventricular inflow velocities, and direct measurement of ventricular pressure, we investigated developmental changes of ventricular diastolic function in the mouse embryos from embryonic days 9.5 to 19.5. Regression analysis showed that peak velocity of A wave (an index of passive compliance) correlated with the area of trabecular myocardium in right ventricle (RV) (r2=0.92, P<0.0001) and left ventricle (LV) (r2=0.93, P<0.0001). Peak velocity of E wave (an index of active relaxation) exponentially correlated with the area of compact myocardium in RV (r2=0.98, P<0.0001) and LV (r2=0.97, P<0.0001). We used these techniques to analyze FOG-2 null embryos. FOG-2 null embryos had thin compact myocardium, higher EDP and E/A ratio, smaller -dP/dt, and diminished sucking pressure than wild-type littermates, indicating that decreased ventricular diastolic function might be the primary cause of embryonic lethality. In conclusion, during embryogenesis the development of compact myocardium tightly regulates the development of ventricular distensibility. Our study in normal mice forms the basis for future studies of embryonic cardiac function in genetically manipulated mice with abnormalities of the cardiovascular system.

Animals↗
PubMed2003

Mutation of the phospholamban promoter associated with hypertrophic cardiomyopathy.

Phospholamban is an endogenous inhibitor of sarcoplasmic reticulum calcium ATPase and plays a prime role in cardiac contractility and relaxation. Phospholamban may be a candidate gene responsible for cardiomyopathy. We investigated genome sequence of phospholamban in patients with cardiomyopathy. PCR-based direct sequence was performed for the promoter region and the whole coding region of phospholamban in 87 hypertrophic, 10 dilated, and 2 restricted cardiomyopathic patients. We found a heterozygous single nucleotide transition from A to G at -77-bp upstream of the transcription start site in the phospholamban promoter region of one patient with familial hypertrophic cardiomyopathy. This nucleotide change was not found in 296 control subjects. Using neonatal rat cardiomyocytes, the mutation, -77A-->G, increased the phospholamban promoter activity. No nucleotide change in the phospholamban coding region was found in 99 patients with cardiomyopathy. We suspect that the mutation plays an important role in the development of hypertrophic cardiomyopathy.

Animals↗
PubMed2003

Growth of stenotic lesions after balloon angioplasty for pulmonary artery stenosis after arterial switch operation.

Little is known about the growth potential of pulmonary stenotic lesions after balloon angioplasty (BA) in patients after the arterial switch operation. The aim of this study was to evaluate the growth potential of pulmonary stenotic lesions after BA and assess the midterm results of BA for pulmonary artery stenosis after the arterial switch operation. Thirty-seven patients who had undergone 52 procedures had repeat catheterization at a median of 43 years (range 1.2 to 9.3 ys) after BA. To adjust growth-related changes in the size of the pulmonary artery, the stenotic diameter was expressed as a percentage of normal (%N). An immediate increase of 63 +/- 45% in the stenotic diameter and a reduction of 51 +/- 33% in the pressure gradient occurred across the stenotic lesions after BA. The right ventricular-aortic systolic pressure ratio decreased from 0.67 +/- 0.24 to 0.51 +/- 0.12 after BA (p <0.0001). Compared with immediate data after BA, there was no significant change in the growth-adjusted diameter of the stenotic lesions (68 +/- 26 %N after BA vs 65 +/- 25 %N at follow-up, p = 0.08), and the pressure gradient (16 +/- 13 mm Hg after BA vs 20 +/- 21 mm Hg at follow-up, p = 0.10). The ventricular-aortic systolic pressure ratio also did not change (0.51 +/- 0.12 after BA vs 0.50 +/- 0.21 at follow-up, p = 0.57). Restenosis occurred in 3 of 26 vessels (12%) after successful BA in which the diameter increased >50% after BA. Our data suggest that pulmonary stenotic lesions after BA develop with age in growing children after the arterial switch operation, and the efficacy of the BA may be long lasting.

Adolescent↗
PubMed2003

Angiographic findings and surgical treatments of coronary artery involvement in Takayasu arteritis.

BACKGROUND: Takayasu arteritis is associated with a low incidence of coronary artery involvement, such as stenosis, obstruction, aneurysm, and coronary steal syndrome, but coronary ischemia can be fatal. METHODS: Between 1972 and April 2001, 81 of 130 patients given a diagnosis of Takayasu arteritis underwent selective coronary angiography, and among them, 31 patients (4 male and 27 female patients; mean age, 41.1 +/- 13.2 years) had abnormal coronary angiographic findings and were recruited for this study. RESULTS: Abnormal coronary findings consisted of 24 coronary artery stenoses of greater than 75%, 3 coronary artery-bronchial artery anastomoses, 3 aneurysmal coronary ectasias, and 1 combined coronary ectasia and anastomosis. Among 24 patients with coronary stenosis, the ostium was most frequently involved (87.5%). Twenty-three of 24 patients with coronary artery stenoses were treated surgically. The mean follow-up duration was 9.65 +/- 6.9 years, with a 100% follow-up rate. Four fistulas and 4 aneurysms in 7 patients were not treated surgically. Coronary steal phenomenon was always associated with occluded pulmonary arteries and pulmonary hypertension. Aneurysmal coronary ectasia was related to severe aortic hypertension with or without aortic regurgitation and atypical coarctation. There were 2 (8.7%) in-hospital deaths and 3 (13%) late deaths. The actuarial survival rate, including in-hospital deaths, was 86.5% +/- 7.3% at 5 years and 81.4% +/- 8.4% at 10 years. CONCLUSION: The incidence of coronary abnormalities is relatively low in patients with Takayasu arteritis; however, surgical treatment is recommended for patients with coronary ostial stenoses because coronary ischemia can be one of the major causes of death.

Actuarial Analysis↗
PubMed2003

Survey of prophylaxis and management of infective endocarditis in patients with congenital heart disease: Japanese nationwide survey.

Guidelines for the prevention and management of infective endocarditis (IE) in children with congenital heart disease (CHD) have not been established, so the aim of this study was to clarify the incidence, practical prevention and management of IE in patients with CHD in Japan through a nationwide survey. A written questionnaire was sent to members of the Japanese Society of Pediatric Cardiology and Cardiac Surgery and information was obtained from 236 cardiologists in 228 institutions. Four hundred and eight patients with IE were hospitalized during 1997 to 2001 (1/173 admissions with CHD including those hospitalized for cardiac catheterization or surgery). Prevention of IE for CHD was undertaken by 92% of cardiologists, usually oral penicillins (73%) and less frequently cephems (18%) were prescribed. The Duke criteria were used as clinical criteria by 38%. Blood culture was performed once only by 40%. Penicillins and aminoglycosides (38%) were frequently administered for management of culture-negative IE. There were variations in the dose and duration of antibiotics for prevention and management of IE. It appears that the prevalence of IE in CHD is rising and the nationwide survey revealed more variations in practical prevention and management of IE in patients with CHD than expected. The results should be helpful in making future guidelines for management of IE in CHD.

Administration, Oral↗
PubMed2003

Current characteristics of infective endocarditis in Japan: an analysis of 848 cases in 2000 and 2001.

The Japanese Circulation Society appointed a committee to develop guidelines for the prevention, diagnosis and management of infective endocarditis in Japan. In making such guidelines, the committee required information on the current clinical characteristics of infective endocarditis and therefore performed a nationwide questionnaire survey of cases from 2000 and 2001. In total, data were received for 848 cases from 277 of the 817 hospitals surveyed. Mean age was 55+/-18 years and most patients were aged in their 50 s or 60 s; 53.9% of the patients had infective endocarditis of unknown origin (without any prior predisposing conditions or procedures) and the second most common etiology was post dental procedures. The most common microorganism was Gram-positive cocci (345 streptococci and 221 staphylococci) and methicillin resistant Staphylococcus aureus (MRSA) was found in 7.3%. Although more than 90% of cases with Streptococcus viridans were sensitive to penicillin G, 6.6% were resistant. All MRSAs were sensitive to vancomycin. The information obtained from the survey assisted in the making of the guidelines, which should become an indispensable tool for all clinicians.

Adult↗
PubMed2003

Arrhythmia and conduction disturbances in patients with congenital heart disease during pregnancy: multicenter study.

The incidence, manifestation and management of arrhythmia in congenital heart disease (CHD) during pregnancy were evaluated in a multicenter study. Of 126 pregnancies in patients with CHD in 17 institutions from January 1991 to December 2000, 29 cases of pregnancy in 27 patients after cardiac repair (mean age, 29+/-4.9 years) were identified with arrhythmias (supraventricular tachyarrhythmia (SVT) in 15, ventricular tachycardia (VT) in 9, high-grade atrioventricular block in 4 and sick sinus syndrome in 3) (group A) and 29 control pregnancies from 29 patients with repaired CHD and no arrhythmias (group B). SVT tended to require anti-arrhythmic medication more than VT (10/15 vs 2/9, p=0.04). Nine different types of anti-arrhythmic agents were successfully administered without maternal complications. There were no maternal deaths in either group. In the comparison of group A with group B, there was lower cardiac functional class (8/29, p=0.04), higher incidence of polysplenia (4/29, p=0.04), and higher incidence of low-birthweight infant (7/29, p=0.02) in the former. It appears that there is a high prevalence of arrhythmias during pregnancy in patients with repaired CHD. Patients with CHD and low cardiac functional class and/or polysplenia could have arrhythmia during pregnancy that results in a low-birthweight infant. Meticulous care for these patients during pregnancy is recommended.

Arrhythmias, Cardiac↗
PubMed2003

[Left ventricular function in adult patients after the atrial switch operation for transposition of the great arteries].

OBJECTIVES: Right ventricular function may deteriorate after the atrial switch operation in patients with transposition of the great arteries, but the effect on left ventricular function is unknown. Chronic left ventricular function was evaluated in adult patients after the atrial switch operation for transposition of the great arteries. METHODS: Right and left ventricular functions were evaluated using data from cardiac catheterization performed in nine patients older than 17 years who had undergone the atrial switch operation for transposition of the great arteries. The mean age at operation was 19 +/- 16 months and the age at catheterization ranged from 17 to 32 years (mean age 23 +/- 5 years). Echocardiography was performed in all patients to evaluate tricuspid regurgitation. Myocardial perfusion studies using technetium-99 m-tetrofosmin were assessed in five patients. RESULTS: Mean right ventricular end-diastolic volume was slightly increased to 122 +/- 27% of the normal value and mean right ventricular ejection fraction was depressed to 44 +/- 5% of the normal value. Left ventricular ejection fraction ranged from 37% to 63% (mean 50 +/- 7%) and was under 50% in four of the nine (44%) patients. Right ventricular ejection fraction was positively correlated with left ventricular ejection fraction(r = 0.72, p < 0.05). All patients had tricuspid regurgitation, mild in four, moderate in four, and severe in one patient. Left ventricular ejection fraction was lower in patients with moderate or severe tricuspid regurgitation(54 +/- 4%) than in patients with mild tricuspid regurgitation(47 +/- 6%, p < 0.05). Mild or moderate perfusion abnormalities were observed in all patients (five of five) who underwent myocardial perfusion studies. Mean right and left ventricular ejection fractions were 43 +/- 3% and 50 +/- 3%, respectively, in patients who underwent myocardial perfusion study, which were under the normal levels. CONCLUSIONS: Left ventricular dysfunction is common in adult patients after the atrial switch operation for transposition of the great arteries. Some right ventricular abnormalities may correlate with the left ventricular dysfunction.

Adolescent↗
PubMed2003

Effect of beraprost sodium on pulmonary vascular resistance in candidates for a Fontan procedure: a preliminary study.

OBJECTIVE: Although long-term prostacyclin(PGI2) therapy in patients with severe pulmonary hypertension (PH)reduces pulmonary vascular resistance (PVR), there have been no reports on its therapeutic effects in patients with mild PH. We investigated the chronic effect of beraprost sodium (BPS), an oral PGI2 analog, in children with mild PH. METHODS: We studied 20 patients who were destined for a Fontan procedure with a mean pulmonary arterial pressure(PAP) of>20 mmHg and/or PVR of>3.0 Wood units. Both the PAP and the PVR in these cases were too high for patients to undergo a successful Fontan procedure. Seven patients received BPS (PG group) and 13 did not (control group). All patients underwent repeat cardiac catheterization to examine pulmonary hemodynamics. RESULTS: In the PG group, the pulmonary-to-systemic flow ratio (Qp/Qs) did not change after BPS administration(1.1 +/- 0.6 vs 1.3 +/- 0.9);however, the mean PAP decreased significantly (25.3 +/- 8.2 vs 19.9 +/- 6.5 mmHg; P < 0.05),as did PVR (3.7 +/- 1.3 vs 2.3 +/- 0.9 Wood units; P < 0.05), whereas the pulmonary artery (PA) index increased significantly (312 +/- 136 vs 375 +/- 165; P < 0.05). In the control group, the mean PAP decreased significantly (24.9 +/- 4.7 vs 19.8 +/- 6.3 mmHg; P < 0.05)and the PA index increased significantly (295 +/- 72 vs 362 +/- 114; P < 0.05). No significant changes in Qp/Qs (1.5 +/- 0.8 vs 1.4 +/- 0.6)or PVR (2.9 +/- 1.3 vs 2.5 +/- 0.8 Wood units) were observed. CONCLUSION: We conclude that long-term BPS administration probably reduces PVR in potential candidates for a Fontan procedure with mild PH. This treatment would reduce the risks associated with the Fontan procedure and would also improve its outcome.

Adolescent↗
PubMed2002

Nonobstructive ASD creation to qualify patients for the Fontan operation: effects on pulmonary hypertension due to restrictive left atrioventricular valve and interatrial communication.

Pulmonary hypertension (PH) due to elevated left atrial pressure (LAp) caused by restrictive left atrioventricular valve and interatrial communication sometimes precludes patients with univentricular heart from undergoing the Fontan operation. We have created atrial septal defect (ASD) for such patients to reduce LAp and then pulmonary arterial pressure (PAp) and pulmonary vascular resistance (Rp) in an attempt to qualify the patients for the Fontan repair. This study was performed to clarify the efficacy and limitation of this approach. Twelve patients with PH (mean PAp > 20 mm Hg and/or Rp > 3.0 Wood's unit/m(2)) due to obstruction at the LA exit underwent ASD creation at the age of 4.0 +/- 4.0 (mean +/- SD) years. Follow-up catheterization 14.9 +/- 15.6 months after the ASD creation demonstrated marked reductions in mean LAp (from 21 +/- 5 to 8 +/- 2 mm Hg), mean PAp (from 39 +/- 13 to 17 +/- 4 mm Hg), and Rp (from 6.2 +/- 4.5 to 2.7 +/- 1.4 Wood's unit/m(2)) compared with those before the procedure (all P < 0.0001). Seven of the 12 patients (58%) qualified for the Fontan operation (mean PAp < 20 mm Hg, Rp < 3.0 Wood's unit/m(2), and Nakata's PA index > or = 250) after the ASD creation. Final surgical outcomes of the seven patients included successful Fontan operation in five and biventricular repair in two. Patients with severe PH [mean PAp > or = 45 mm Hg (n = 6) or Rp > or = 4.5 Wood's unit/m(2) (n = 5)] before the ASD creation qualified less frequently for the Fontan repair than those with mild PH [mean PAp < 45 mm Hg (n = 6; 17% vs. 100%; P = 0.008) or Rp < 4.5 Wood's unit/m(2) (n = 7; 20 vs. 86%; P = 0.045)]. Patients with PA banded after 6 months of age (n = 3) qualified less frequently for the Fontan operation than those banded before 6 months of age (n = 6; 0 vs. 83%; P = 0.048). These data suggest that ASD creation is an effective approach to qualify patients for the Fontan operation in the presence of restrictive left atrioventricular valve and interatrial obstruction, except those with longstanding severe PH following delayed PA banding.

Cardiac Catheterization↗
PubMed2002

The role of endothelin in oxygen-induced contraction of the ductus arteriosus in rabbit and rat fetuses.

The role of endothelin in oxygen-induced contraction remains controversial. The present study was designed to investigate the role of endothelin in O2-induced contraction in the isolated ductal preparation of rabbit and rat, using the endothelin receptor antagonists, bosentan (antagonist for both ET-A and ET-B receptors) and BQ 485 (an ET-A selective antagonist). The ductus was isolated from fetal rabbits at 30 days of gestation (term 31 days) and fetal rats at 21 days of gestation (term 22 days). In the rabbit ductus with intact endothelium, 13% of the O2-induced contraction was inhibited by bosentan and 14% by BQ 485. In the rabbit ductus without endothelium, bosentan did not cause significant inhibition of the oxygen-induced contraction. In the rat ductus with intact endothelium, about 44% of the O2-induced contraction was inhibited by bosentan. In the rat ductus without endothelium, O2-induced contraction was 20% less than that in the ductus with intact endothelium. In the rat ductus without endothelium, bosentan further decreased the oxygen-induced contraction by about 24%. These data suggest that (1) endothelin plays a significant role in O2-induced contraction in the isolated ductus arteriosus, (2) there is a species difference in the degree of contribution of endothelin to the O2-induced ductal contraction, and (3) there is a species difference in the degree of contribution of the endothelium and vascular smooth muscle cells to the release of endothelin from the ductus arteriosus.

Animals↗
PubMed2002

Expression of slow skeletal myosin heavy chain 2 gene in Purkinje fiber cells in chick heart.

In avian, there are three slow skeletal myosin heavy chain (MHC) isoforms, slow skeletal MHC 1, 2, and 3. While slow skeletal MHC 3 has been characterized, slow skeletal MHC 1 and 2 are not yet fully studied. To determine the complete sequence of slow skeletal MHC 2, we isolated six overlapping cDNA clones, each encoding a portion of chick slow skeletal MHC 2, using the reverse transcription polymerase chain reaction (RT-PCR). The entire slow skeletal MHC 2 cDNA consisted of 5927 nucleotides including a 104 bp 3'-untranslated region and encoded 1941 amino acids. Using one of the cDNA clones, we made a probe for in situ hybridization. We also used immunohistochemistry to localize slow skeletal MHC 2 in skeletal and cardiac tissues. These studies showed that in addition to its expected expression in the adult chicken slow skeletal muscle, slow skeletal MHC 2 was expressed in the subendocardial cluster of cells and around the blood vessels within the ventricle of late embryos and adults. This isoform was not expressed in the myocardium throughout the life of the chicken. Based on morphological criteria as well as rich desmin expression, we concluded that the subendocardial cluster of cells were Purkinje cells. Although the physiological significance of the slow skeletal MHC expression remains elusive at this time, this MHC isoform may be used as a specific marker for Purkinje cells.

Animals↗