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Biomedical subjects

K Momma

Publications and source records attributed to K Momma.

At least 109 records · Page 6Linked to original sources
PubMed1994

Intravascular stents for management of pulmonary artery and right ventricular outflow obstruction.

This study was performed to determine the efficacy of balloon-expandable stents in the treatment of branch pulmonary artery-stenoses and conduit stenosis in children. A total of eight stainless steel stents were implanted in seven patients. Three patients had tetralogy of Fallot with pulmonary artery stenosis following total correction, one patient had conduit stenosis following correction of transposition of the great arteries, one patient had intra-cardiac conduit stenosis after septation for single left ventricle, and two patients had pulmonary artery stenosis after Fontan operation. Six stents were placed in the branch pulmonary arteries, one in the extracardiac conduit, and one in the intracardiac conduit. The mean age at implantation was 13 +/- 3 years and the mean weight 37 +/- 12 kg. Follow-up time ranged from 0.3-2 years. The diameter of pulmonary arteries with stenoses increased from 5.6 +/- 2.2 mm to 10.6 +/- 1.8 mm (n = 7). The systolic pressure gradient decreased from 56 +/- 26 mmHg to 22 +/- 16 mmHg (n = 5). No embolization or thrombotic event has been noted. One stent placed in the intracardiac conduit was compressed and fractured. These data indicate that balloon-expandable stents are useful in the treatment of pulmonary artery branch stenoses and extracardiac conduit stenosis in children. The use of stents for intracardiac stenosis may result in stent fracture.

Adolescent↗
PubMed1994

Asynchronous volume changes of the two ventricles after Fontan operation in patients with a biventricular heart.

Coordinated contraction of the ventricle is an important determinant of pump function, which seems to be particularly important in Fontan circulation with one pumping ventricle. We analyzed the synchronism of contraction of the two ventricles in 11 patients with a biventricular heart who had undergone Fontan operation. Curves representing ventricular volume changes in a cardiac cycle measured on angiograms were smoothed and divided into 20 segments. We calculated the number of segments of the same directional volume changes (synchronous changes) between the two ventricles (synchronous ratio). We also calculated the total volume of the two ventricles (the two as one whole ventricle) by adding their volumes in each segment and calculated the ratio (stroke volume ratio) of the aortic stroke volume from the whole ventricle to the sum of stroke volumes of the morphological right and left ventricles. If the two ventricles ejected the blood in a completely synchronous manner, these ratios should be 1.0. In seven patients with synchronous ratios of 0.75 or greater and a stroke volume ratio of greater than 0.95, the cardiac index was 3.2 +/- 0.3 l/min/m2, the maximum total volume (corresponding to end-diastolic volume) was 106 +/- 45% normal, and the ejection fraction was 0.44 +/- 0.10. In four patients with ratios of less than 0.70 and 0.95, respectively, the parameters were 2.4 +/- 0.5 (P < 0.05), 193 +/- 92%, and 0.33 +/- 0.08, respectively. The synchronous ratio was inversely correlated with cardiac output. In conclusion, synchronism of the cardiac cycle of the two ventricles affects Fontan circulation in patients with a biventricular heart.

Adolescent↗
PubMed1994

Prediction of quality of life at long-term follow-up after Fontan operation by scoring risk factors.

Many factors will determine the quality of life at long-term follow-up after the Fontan operation. We tried to predict the long-term outcome of modified Fontan operation based on the combined assessment of various preoperative data. The preoperative condition was evaluated by a scoring system in which multilevel scores (from zero to 8 points) were given to a total of 14 morphological and physiological factors according to the contribution of each factor to mortality. The major factors were the association of the extracardiac total anomalous pulmonary venous connection, pulmonary arterial vascular resistance, mean pulmonary arterial pressure, PA index, ejection fraction of the main ventricle, and creatinine clearance. Points for each factor were determined according to surgical mortality, with zero points indicating no increased risk. The total score, i.e., the sum of the points for each item, in each patient was analyzed in relation to the patient's quality of life over a long-term follow-up, as evaluated by questionnaires. Twenty-six of 29 patients with scores of 5 or less showed normal or almost normal life long after the operation, whereas 5 of 10 with higher scores had restricted physical and daily activity. In conclusion, good preoperative condition predicts a good quality of life long after the Fontan operation. In addition, the concept of taking into account all possible risk factors as a comprehensive indicator may be useful in predicting long-term results.

Adolescent↗
PubMed1994

Ventricular function after anatomic repair in patients with atrioventricular discordance.

Since June 1989, 18 patients with atrioventricular discordant anomalies under 15 years of age underwent anatomic correction, or double switch operation, with 2 hospital deaths (11%). Ages ranged from 1 year 4 months to 12 years (mean 7.2 years) and body weights ranged from 7.1 to 32.5 kg (mean 20.1 kg) at operation. Visceral situs was solitus in 12 and inversus in 6. Ventriculoarterial connection was discordant in 4 and double-outlet in 14. All had associated congenital cardiac anomalies consisting of ventricular septal defect in 17, atrial septal defect in 9, pulmonary atresia in 10, pulmonary stenosis in 6, systemic tricuspid regurgitation in 9, mitral regurgitation in 6, bilateral superior venae cavae in 6, patent ductus arteriosus in 6, Wolff-Parkinson-White syndrome in 2, and congenital atrioventricular block in 1. Previous palliation had been performed 19 times in 11 patients including systemic-pulmonary shunts in 10 patients and pulmonary banding in 1 patient. Anatomic correction consisted in the Mustard procedure in 12 or the Senning procedure in 6 at the atrial level and in external conduit repair in 14, arterial switch operations in 3, or direct anastomosis between the pulmonary artery and right ventricle in 1 at the ventriculoarterial level. The arterial switch operation was indicated in patients with a normal pulmonary valve, and external conduit repair was indicated for patients with pulmonic stenosis or atresia. Anatomic right ventricular end-diastolic volume showed significant reduction from 122.2% +/- 46.3% of normal to 78.8% +/- 24.0%, mainly owing to unloading of the ventricle after the operation (p < 0.0003). Right ventricular ejection fraction remained unchanged (56% +/- 8% to 56% +/- 6%). Anatomic left ventricular end-diastolic volume and left ventricular ejection fraction remained unchanged before and after the operation: volume 134.6% +/- 50.0% of normal to 127.3% +/- 32.8% and ejection fraction from 61% +/- 8% to 56% +/- 8%. Cardiac index averaged 3.1 +/- 0.5 L/min per square meter after the operation. The double switch operation is best indicated in patients with atrioventricular discordance associated with systemic tricuspid regurgitation and/or with poor systemic right ventricular function.

Cardiac Output↗
PubMed1993

Scintigraphic monitoring of coronary artery occlusion due to Kawasaki disease.

Noninvasive monitoring of the process of coronary occlusion will probably aid in determining the timing of therapeutic interventions for Kawasaki disease. A pair study of coronary angiography and thallium scintigraphy after dipyridamole infusion-single-photon emission computed tomography with dipyridamole infusion (Dp-SPECT) was repeated at least twice at intervals of several years in 29 patients, and these findings were compared and analyzed in a chronologic manner. The current study demonstrated that angiographic stenosis was more severe, with an increase in the severity of the perfusion defect. Positive rates determined by Dp-SPECT increased with increasing severity of stenosis on angiography. Angiographic findings from the first to the second serial study that showed worsening, no change and improvement were correctly diagnosed from scintigraphic changes in 94% of coronary arterial lesions. About half of the arteries with progression in stenotic severity could be found before complete occlusion by scintigraphic monitoring. It is concluded that Dp-SPECT can be used as a noninvasive monitor of the occurrence and progression of coronary stenoses due to Kawasaki disease.

Coronary Aneurysm↗
PubMed1993

In-situ pulmonary vascular morphology and lung volume in the fetal and neonatal rat.

In situ cross-sectional morphology of the pulmonary arteries, veins, and lung volumes were studied following rapid whole-body freezing of the fetal and neonatal rat. In the fetus, the right and left main pulmonary arteries were much smaller than the pulmonary trunk, and the ratio of the internal diameter of the right or the left pulmonary artery to the diameter of the pulmonary trunk was 0.44 and 0.38, respectively. One day after birth, the right and the left main pulmonary arteries enlarged, and the ratio of the right pulmonary artery to the pulmonary trunk increased to 0.82. The proximal right and left pulmonary arteries immediately adjacent to the bifurcation enlarged slowly, and showed diffuse narrowing at the proximal portions adjacent to the bifurcation. The narrowing disappeared 3 and 4 days after birth as the proximal pulmonary artery enlarged and the ratio of the right pulmonary artery to the pulmonary trunk reached 0.8. The pulmonary vein showed rapid enlargement in these neonates, concordant with the enlargement of the pulmonary arteries. Lung volume increased to 131% of the fetal volume 10 min after caesarean section. These studies quantitated neonatal pulmonary vascular adaptation. Delayed enlargement of the pulmonary arteries adjacent to the bifurcation in the neonatal period was shown, and presented a morphologic basis for the physiologic gradient and transient systolic murmur in the pulmonary arteries in human neonates.

Animals↗
PubMed1993

Balloon angioplasty for postoperative pulmonary artery stenosis in transposition of the great arteries.

OBJECTIVES: This study was designed to assess the success rate and determinants of success or failure of balloon angioplasty for postoperative pulmonary stenosis in patients with transposition of the great arteries. BACKGROUND: Previous reports have suggested that pulmonary stenosis that develops after the arterial switch operation is not likely to be dilated. METHODS: Twenty-eight patients with transposition of the great arteries underwent 39 balloon angioplasty procedures after the arterial switch operation. The mean age at dilation was 4.5 +/- 2.2 years (range 0.7 to 9.8), and the interval between operation and balloon dilation was 3.6 +/- 1.8 years. The criterion of successful dilation was a > or = 50% increase in predilation diameter or a > or = 50% decrease in predilation pressure gradient. If the right ventricular/aortic pressure ratio decreased by > or = 0.2, so that the ratio became < 0.68, reoperation was thought to be not indicated. RESULTS: The success rate of balloon angioplasty for pulmonary artery stenosis was 51% (20 of 39 dilations). The mean age at dilation in the group with successful dilation (3.6 years) was significantly younger than that in the group with unsuccessful dilation (5.4 years). The interval between operation and dilation in the successful dilation group (2.4 years) was significantly less than that in the unsuccessful dilation group (4.6 years). In 13 patients who underwent balloon angioplasty < 3.5 years after operation, balloon dilation was successful in 92%. The balloon/artery ratio was significantly greater in the successful than in the unsuccessful dilation group. A right ventricular/aortic pressure ratio > or = 0.68 was observed in 20 patients, and reoperation was not indicated in 10 patients (50%). There was no death, but one pulmonary artery rupture that did not require surgical intervention occurred. Aneurysmal dilation of the pulmonary artery was observed in three patients. CONCLUSIONS: These data indicate that although the success rate of balloon angioplasty for pulmonary artery stenosis after the arterial switch operation is low (approximately 50%), balloon angioplasty can be the first therapeutic choice owing to the low complication rate and the potential benefit of the procedure. The success rate can be high if angioplasty is performed < 3.5 years after operation and a balloon of adequate size is used.

Age Factors↗
PubMed1993

An autopsied case of Williams syndrome complicated by moyamoya disease.

An 18 year old girl with typical clinical features of Williams syndrome suddenly died of intracerebral hemorrhage due to moyamoya disease. Autopsy revealed vascular abnormalities, such as supravalvular aortic stenosis (SAS) and an abnormal complicated cerebrovascular network in the cerebral arteries. The arterial wall of the SAS lesion consisted of thickened medial tissue showing elastic disorganization with prominence of the smooth muscle cells. The narrowed vessels of the circle of Willis showed intimal thickening with an extremely wavy internal elastic lamina and marked thinning of the media. To our knowledge, this is the first report of moyamoya disease associated with Williams syndrome.

Abnormalities, Multiple↗
PubMed1993

Conotruncal anomaly face syndrome is associated with a deletion within chromosome 22q11.

The conotruncal anomaly face syndrome was described in a Japanese publication in 1976 and comprises dysmorphic facial appearance and outflow tract defects of the heart. The authors subsequently noted similarities to Shprintzen syndrome and DiGeorge syndrome. Chromosome analysis in five cases did not show a deletion at high resolution, but fluorescent in situ hybridisation using probe DO832 showed a deletion within chromosome 22q11 in all cases.

Abnormalities, Multiple↗
PubMed1993

Mechanisms of oxygen-induced contraction of ductus arteriosus isolated from the fetal rabbit.

The present study was designed to investigate the effect of O2 on intracellular Ca concentration ([Ca]i) in the ductus arteriosus and the mechanisms for O2-induced ductal contraction. The force of isometric contraction of the ring of the ductus arteriosus isolated from fetal rabbits at 30 days of gestation (term, 31 days) was measured. The ductus arteriosus was loaded with fura 2, a calcium-sensitive dye, and [Ca]i was determined from the ratio of fluorescence intensity at 340 and 380 nm excitation wavelengths. The ductus arteriosus was initially superfused with hypoxic control solutions and contraction was induced by application of oxygenated solutions. The O2-induced contraction of the ductus arteriosus was associated with increases in [Ca]i and was eliminated in the absence of extracellular calcium. An increase in [K]o from 5 to 50 mM, which causes membrane depolarization, induced ductal contraction. The calcium channel blockers verapamil, diltiazem, and nickel caused a similar inhibition of O2-induced contraction as well as KCl-induced contraction. The role of intracellular calcium stores in O2-induced ductal contraction was examined using ryanodine, an inhibitor of calcium uptake and release from the sarcoplasmic reticulum. The inhibition of O2-induced contraction by ryanodine was minimal. Infusion of glibenclamide, an inhibitor for opening the ATP-sensitive potassium channel, caused contraction of the ductus arteriosus in the hypoxic solution. Cromakalim, an opener of ATP-sensitive potassium channels, completely relaxed the contraction induced by O2. These data suggest that O2 increases [Ca]i and causes contraction in the ductus arteriosus. Application of O2 may change from anaerobic to aerobic metabolism and depolarize membrane potential by closing the ATP-sensitive potassium channel, which in turn increases calcium influx via the voltage-dependent calcium channel. Mechanisms other than the ATP-sensitive potassium channel may also be involved in the O2-induced contraction and remain to be studied.

Animals↗
PubMed1993

In situ morphology of the aorta and common iliac artery in the fetal and neonatal rat.

In situ cross-sectional morphology of the ascending, descending, and abdominal aorta and the common iliac arteries was studied after rapid, whole-body freezing of fetal and neonatal rats. In the fetus, the ascending aorta was smaller than the descending aorta and the abdominal aorta was relatively large, continuing to the large right common iliac artery and the umbilical artery. After birth, the umbilical artery and the ductus arteriosus closed rapidly, and the size of the aorta changed within a few days. The ascending aorta became larger than the descending aorta in 2 d, and the abdominal aorta became smaller, especially at the infrarenal part. The right common iliac artery, which continues to the umbilical artery in fetal life, became smaller, and its diameter was the same as that of the left common iliac artery 2 d after birth.

Animals↗
PubMed1993

Combined assessment with myocardial contractility and an index related to ventricular afterload in patients with isolated severe mitral regurgitation undergoing valve replacement. A retrospective study.

The afterload to the left ventricle increases following valve replacement in chronic mitral regurgitation (MR), yet there has been no study taking into account left ventricular (LV) afterload. In 43 patients with isolated chronic MR undergoing mitral valve replacement (MVR), we calculated LV wall stress using preoperative LV end-diastolic dimensions and diastolic aortic pressure (predictive LV wall stress = pWS). This value would represent LV wall stress at the instant of aortic valve opening immediately after MVR, assuming that LV end-diastolic dimensions and the aortic pressure did not change after operation. We also calculated end-systolic wall stress/volume index (ESS/ESVI) ratio, an index of myocardial function. None of 15 patients with the ESS/ESVI ratio > 1.6 had postoperative mortality or morbidity, whereas among the 26 patients with the ESS/ESVI ratio < 1.6, 12 patients had mortality (3 patients) and/or morbidity requiring intraaortic balloon pumping or prolonged catecholamine support. Three patients who died had pWS > 200 kdynes/cm2. Including these 3, all 5 patients whose pWS > 200 had mortality or severe morbidity immediately after surgery. In contrast, among the 38 patients with lower pWS, none died and only 7 patients (18%) had morbidity. Thus, patients who had a low contractility index and a high predictive afterload value had high mortality and morbidity. We conclude that the prediction of postoperative mortality and morbidity is improved by combined assessment of myocardial function and the hypothetical postoperative LV afterload.

Catecholamines↗
PubMed1992

Cellular retinoic acid binding protein type II was preferentially localized in medium and posterior parts of the progress zone of the chick limb bud.

The expression and distribution of cellular retinoic acid binding protein II (CRABP II) was examined in chick limb buds. CRABP II was detected in the limb buds at Hamburger and Hamilton (1) stage 21 and the amount of CRABP II was gradually increased during stages 21-27 and thereafter decreased. CRABP II was mainly located in the progress zone, and the dorsal and ventral premuscular mass in the proximal region of the limb buds at stage 23. CRABP II was preferentially localized in the medium and posterior parts rather than the anterior part of the progress zone; The content of CRABP II in the medium and posterior parts was 8-9 times more than that in the anterior part.

Animals↗
PubMed1992

Imperforate tricuspid valve with dysplasia of the right ventricular myocardium, pulmonary valve, and coronary artery: a clinicopathological study of nine cases.

Nine cases of imperforate tricuspid valve associated with dysplasia of the right ventricular myocardium, pulmonary valve, and right coronary artery are described. The mean frontal QRS axis of the electrocardiograms did not indicate left axis deviation in seven of the nine. Two-dimensional echocardiograms showed an imperforate tricuspid valve, normally aligned atrioventricular septum, and an irregular-shaped right ventricular cavity with a thin wall. In three cases with absence of the pulmonary valve, pulsed Doppler echocardiograms of the right ventricular outflow tract revealed antegrade flow during systole and retrograde flow during diastole, and selective angiography through a persistent ductus arteriosus showed retrograde filling of the blind-ended right ventricular cavity via the main pulmonary artery. Necropsy examinations showed an imperforate tricuspid valve with a thin-walled aneurysmal right ventricle in all six cases examined. Pulmonary atresia was observed in two cases, and the absence of the pulmonary valve in four. The right coronary artery was hypoplastic in four cases and absent in two. A shunt operation should be carried out in early infancy to prevent hypoxia after closure of the ductus arteriosus.

Abnormalities, Multiple↗
PubMed1992

Color Doppler and transesophageal echocardiography of vascular sling.

Three patients with vascular sling were studied by two-dimensional and color Doppler echocardiography and angiocardiography. One case was associated with atrial septal defect and another with tetralogy of Fallot and patent ductus arteriosus. The third case had no associated intracardiac anomalies. Color Doppler flow mapping was performed in all three patients, and transesophageal echocardiography was studied in two patients. Color Doppler echocardiography showed the characteristic features of this congenital anomaly in all three patients, especially in detecting the site of anomalous origin of the left pulmonary artery. A small patent ductus arteriosus was misinterpreted as the normal left pulmonary artery in one patient. Small pulmonary arteries in the patient with tetralogy of Fallot made the diagnosis difficult. Using transesophageal echocardiography, we clearly identified the trachea, esophagus, and abnormal left pulmonary artery.

Airway Obstruction↗