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Biomedical subjects

K Nishigaki

Publications and source records attributed to K Nishigaki.

At least 73 records · Page 4Linked to original sources
PubMed1995

A bicuspid pulmonary valve is not a contraindication for the arterial switch operation.

There are no obvious criteria concerning the optimal repair for complete transposition with bicuspid pulmonary valve if neither the organic changes in the valve nor the pressure gradient between the left ventricle and the pulmonary trunk are severe. Instead of intraatrial switching or intraventricular rerouting in such circumstances, we have proceeded to the arterial switch procedure in 6 patients with an adequate diameter of the pulmonary valve (greater than 100% of the calculated normal aortic orifice). Postoperative catheterization (at approximately 8 months after the procedures) showed no pressure gradient between the left ventricle and the neoaorta except for a finding of 34 mm Hg difference in 1 patient who had undergone simultaneous subpulmonary myotomy. Echocardiography (7 years later in the longest follow-up) has shown no more than slight regurgitation across the bicuspid neoaortic valve, with no progressive increase of blood velocity across the valve. From these results in the middle term, we conclude that the arterial switch procedure remains an option of choice for patients with initially bicuspid pulmonary valve, providing there is no severe subpulmonary stenosis.

Aorta↗
PubMed1995

Coronary arterial anatomy in double-outlet right ventricle with subpulmonary VSD.

We have examined 38 hearts with a double-outlet right ventricle with a subpulmonary ventricular septal defect. We divided the hearts into three groups according to the angle between the planes formed between the outlet septum and the remainder of the muscular ventricular septum; namely, at approximately right angles (15 hearts), parallel (11 hearts), and at an acute angle (12 hearts). The coronary arterial pattern corresponding to that seen in the normal heart was present in 11 hearts (73%) of the "right angle" group, in only one heart (8%) of the "acute angle" group, and in none of the "parallel" group. In contrast, the most common pattern in the setting of complete transposition was observed in none, 8%, and 91% of each group, respectively. Other diverse patterns were recognized in the hearts in the acute angle group, and the incidence of abnormal branching was significantly higher in this than in the other groups (p < 0.01). Knowledge of these anatomic variations in the course of the coronary arteries, some of which would cause problems at either definitive repair or reoperation, are essential for those seeking to achieve optimal surgical repair.

Coronary Vessel Anomalies↗
PubMed1995

What factors affect ventricular performance after a Fontan-type operation?

Postoperative conditions after a Fontan-type operation, particularly as they affect results in the early term, are thought to depend on factors such as the state of pulmonary circulation and ventricular function. In this study, we attempted to determine the factors that influence ventricular characteristics in the middle term after Fontan-type procedures. Catheterization was performed at a mean of 15 months after operation in 57 patients with univentricular atrioventricular connection who underwent the operation between 1.0 and 22.6 years of age. End-diastolic volume, end-systolic volume, ejection fraction, and end-diastolic pressure of the systemic ventricle were analyzed together with an estimation of the systemic flow index. These parameters were influenced significantly by the presence of atrioventricular valve insufficiency. The morphologically left ventricle showed a better ejection fraction than did the morphologically right ventricle, whereas the systemic flow index was greater in patients undergoing total cavopulmonary connection than in those receiving an atriopulmonary connection. Young age was significantly associated with a better postoperative contractility, whereas the potential for impaired ventricular compliance was suggested in several patients undergoing operation after 4 years of age. On the basis of our results, we conclude that total cavopulmonary connection performed at a young age should be the surgical procedure of choice and that atrioventricular insufficiency must be treated properly at, and even after, the initial definitive repair.

Adolescent↗
PubMed1995

Biventricular repair in cardiac isomerism. Report of seventeen cases.

Ninety-three patients with cardiac isomerism were treated surgically from July 1985 to June 1991. Among them, three patients with right and 14 with left isomerism underwent biventricular repair. Ages ranged from 4 months to 41 years (mean 4.8 years). Anatomic repair was accomplished in 15 patients and functional repair with the right ventricle used as the systemic ventricle in two patients. Methods of atrial septation to separate pulmonary venous flow from systemic venous flow included atrial partition with a straight patch in seven patients, intraatrial rerouting with a tailored baffle in five, and a Mustard-type atrial switch in five. One hospital death (5.8%) and two late deaths (12%) occurred. Two patients required reoperation (12%), one reconstruction of a stenotic systemic venous connection and one mitral valve replacement because of incompetence. Surgically induced complete atrioventricular block was not observed in any of the patients. Optimal atrial septation offers the possibility of biventricular repair for patients with acceptable intraventricular structure.

Abnormalities, Multiple↗
PubMed1995

Alternations in atrial natriuretic peptide release after DC cardioversion of non-valvular chronic atrial fibrillation.

The response of atrial natriuretic peptide (ANP) release to haemodynamic influences after cardioversion of atrial fibrillation has not been fully examined. We measured plasma concentrations of ANP and assessed haemodynamic changes 60-120 min after DC cardioversion in 22 patients with non-valvular chronic atrial fibrillation. Passive leg elevation to enhance volume expansion was performed 60 min after DC cardioversion. Sinus rhythm was restored in 18 of the 22 patients (successful DC cardioversion group). The control group consisted of seven patients with non-valvular chronic atrial fibrillation who did not undergo DC cardioversion (atrial fibrillation control group). In the successful DC cardioversion group, the mean pulmonary artery wedge pressure decreased significantly 15 min after cardioversion (P < 0.05) and then remained unchanged. Plasma concentrations of ANP also decreased significantly 15 min after cardioversion (P < 0.05). Furthermore, there was an additional significant decrease in ANP levels for up to 60 min after cardioversion (P < 0.05 from 15 min). Passive leg elevation for 15 min led to an increase in the mean pulmonary artery wedge pressure (P < 0.01) and right atrial pressure (P < 0.05), but did not result in increased plasma concentrations of ANP (47.1 +/- 27.6 vs 43.9 +/- 34.4 pg.ml-1, mean +/- SD, P = ns). In the atrial fibrillation control group, passive leg elevation increased the mean pulmonary artery wedge pressure (P < 0.01), the mean right atrial pressure (P < 0.05) and plasma concentrations of ANP (139.9 +/- 85.8 vs 168.1 +/- 108.2, P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Effects of ventilation and pleural effusion on measurements of airway thermal volume and blood flow in dog lungs.

We studied the effects of ventilation and pleural effusion on measurements of airway thermal volume (ATV) and pulmonary blood flow (PBF) by using the airway gas thermometry method of V. B. Serikov, M. S. Rumm, K. Kambara, M. I. Bootomo, A. R. Osmack, and N. C. Staub (J. Appl. Physiol. 72: 944-953, 1992) in 39 anesthetized dogs with or without lung edema or pleural effusion. To examine the differential effects of increased-pressure and increased-permeability lung edema on accuracy and sensitivity of ATV and PBF, two models of lung edema were induced by intravenous infusion of a Dextran 70 solution and alloxan monohydrate, respectively. Dogs were hyperventilated for 3 min by using a wide range of minute ventilation (VE) to produce two steady-state conditions of airway temperature. Higher levels of VE increased an estimated amount of ATV. The ATV produced by hyperventilation at VE values of 559, 158, and 72 ml.min-1.kg-1 was consistent with the gravimetric total lung mass, the blood-free wet lung weight, and the extravascular lung water volume, respectively. The coefficient of lung thermal conductivity, a practical index of the rate of heat conduction through tissue from lung vessels, was related to the ratio of the decrease in expired air temperature to VE, and estimated PBF was consistent with the thermodilution cardiac output. Pleural effusion had little effect on measurements of ATV and PBF. However, ATV and PBF showed increased variation in dogs with dextran-induced lung edema.

Air Pressure↗
PubMed1994

Computer prediction of general PCR products based on dynamical solution structures of DNA.

A computer program which can predict general PCR products was developed and experimentally verified to be useful. This means that the approximation of solution structures of DNA based solely on Watson-Crick base pairing is effective. Intramolecular higher structures were shown to be responsible for the discrepancies between the predictions and the experimental results. This study provides a theoretical background to arbitrarily primed (or random) PCR. Other basic issues relating to general PCR are also discussed.

Base Sequence↗
PubMed1994

Genetic determinants of feline leukemia virus-induced lymphoid tumors: patterns of proviral insertion and gene rearrangement.

The genetic basis of feline leukemia virus (FeLV)-induced lymphoma was investigated in a series of 63 lymphoid tumors and tumor cell lines of presumptive T-cell origin. These were examined for virus-induced rearrangements of the c-myc, flvi-2 (bmi-1), fit-1, and pim-1 loci, for T-cell receptor (TCR) gene rearrangements, and for the presence of env recombinant FeLV (FeLV-B). The myc locus was most frequently affected in naturally occurring lymphomas (32%; n = 38) either by transduction (21%) or by proviral insertion (11%). Proviral insertions were also common at flvi-2 (24%). The two other loci were occupied in a smaller number of the naturally occurring tumors (fit-1, 8%; pim-1, 5%). Examination of the entire set of tumors showed that significant numbers were affected at two (19%) or three (5%) of the loci. Occupation of the fit-1 locus was observed most frequently in tumors induced by FeLV-myc strains, while flvi-2 insertions occurred with similar frequency in the presence or absence of obvious c-myc activation. These results suggest a hierarchy of mutational events in the genesis of feline T-cell lymphomas by FeLV and implicate insertion at fit-1 as a late progression step. The strongest links observed were with T-cell development, as monitored by rearrangement status of the TCR beta-chain gene, which was positively associated with activation of myc (P < 0.001), and with proviral insertion at flvi-2 (P = 0.02). This analysis also revealed a genetically distinct subset of thymic lymphomas with unrearranged TCR beta-chain genes in which the known target loci were involved very infrequently. The presence of env recombinant FeLV (FeLV-B) showed a negative correlation with proviral insertion at fit-1, possibly due to the rapid onset of these tumors. These results shed further light on the multistep process of FeLV leukemogenesis and the relationships between lymphoid cell maturation and susceptibility to FeLV transformation.

Animals↗
PubMed1994

Usefulness of the pulmonary vein flow velocity-time profile as an estimate of left atrial storage fraction.

During ventricular systole, the left atrium (LA) stores a certain amount of ventricular stroke volume; this is defined as an LA storage volume. From cineangiocardiograms, an LA storage fraction is obtained as the ratio of the LA storage volume to left ventricular stroke volume. From the pulmonary vein (PV) flow velocity-time profile, the LA storage fraction may be estimated as a ratio of the PV flow velocity-time integral during systole (Sa) to a sum of that during systole and diastole (Sa+Da), namely, Sa/(Sa+Da), provided that the PV cross-sectional area remains relatively unchanged during one cardiac cycle and that the PV flow velocity-time profile is similar in any of the PVs draining to the LA. To evaluate usefulness of Doppler echocardiographic method of estimating the LA storage fraction, the authors measured the LA storage fraction from the left upper PV flow velocity-time profile by transesophageal Doppler echocardiography and compared it with the LA storage fraction from conventional cineangiocardiographic volumes. Subjects were 23 patients with a variety of cardiac diseases in normal sinus rhythm, ranging from eighteen to seventy-four years of age. The LA storage fraction was 0.58 +/- 0.12 (mean +/- SD) from cineangiocardiography and 0.64 +/- 0.08 from Doppler echocardiography larger than that from cineangiocardiography (P < 0.01), the correlation was good (r = 0.643). The authors conclude that the left upper PV flow velocity-time profile appears to provide a better correlation with that by cineangiography and may be used as a reliable quantitative estimate of the LA storage fraction.

Adult↗
PubMed1994

A study on left atrial transport function. Effect of age or left ventricular ejection fraction on left atrial storage fraction.

Left atrial (LA) storage fraction is defined as the ratio of storage volume of the left atrium (LA) during ventricular systole to left ventricular (LV) stroke volume. To test their hypothesis that left atrial (LA) storage fraction is increased to compensate for impaired LV filling in the heart of aged subjects or with impaired LV ejection fraction, the authors studied 33 "normal" subjects and 25 patients with coronary artery disease. LA volume was measured by LA cineangiocardiography, and LV stroke volume and LV ejection fraction were measured by LV cineangiocardiography. To further evaluate the determinants of changes in LA storage fraction, they measured the ratio of LA active release volume to LV stroke volume, and the ratio of LA passive release volume to LV stroke volume. In "normal" subjects, LA storage fraction was increased with age (r = 0.584, P < 0.01). In patients with coronary artery disease, LA storage fraction was increased as LV ejection fraction was decreased (r = -0.525, P < 0.01). In both cases, LA active release fraction was significantly associated with changes in LA storage fraction rather than in LA passive release fraction. They conclude that LA storage fraction may be an important determinant of LV filling mainly through the LA active release fraction.

Adolescent↗
PubMed1994

Double switch operation in cardiac anomalies with atrioventricular and ventriculoarterial discordance.

Since June 1987, 10 of 19 consecutive patients with atrioventricular and ventriculoarterial discordance (average age 4 +/- 2 years) had undergone a double switch operation with the morphologically left ventricle used as a systemic ventricle. There were two combinations of procedures. Atrial switch combined with arterial switch was used in two patients who had a normal pulmonary valve. Atrial switch combined with ventriculoarterial switch by Rastelli's procedure was used in eight patients with pulmonary stenosis or atresia and a large ventricular septal defect. One early death and two late deaths have occurred in a postoperative follow-up period of up to 4 years. Subsequent problems were mainly related to the results of atrial switch procedures in patients who had a small atrium because of low pulmonary flow, especially in patients with apicocaval juxtaposition. Our experience suggested that the double switch operation would open a new era of definitive surgical treatment in half of the patients with atrioventricular and ventriculoarterial discordance.

Aorta↗
PubMed1993

A common proviral integration region, fit-1, in T-cell tumors induced by myc-containing feline leukemia viruses.

Feline leukemia viruses carrying transduced v-myc genes (myc-FeLV) induce tumors of clonal origin, suggesting that activated myc alone is not sufficient for tumorigenesis. To investigate the hypothesis that insertional mutagenesis plays a role by activating genes which collaborate with v-myc, we looked for evidence of common proviral integration sites in these tumors. By inverse polymerase chain reaction we identified a 6-kb domain, designated fit-1, in which FeLV proviruses were inserted in four of nine (44%) T-cell tumors induced by myc-FeLV. The fit-1 locus was mapped to feline chromosome B2 and appears to be distinct from known oncogenes located on this chromosome. Fit-1 represents a novel common proviral integration region which may harbor a cellular gene which acts in concert with the myc gene in T-cell tumorigenesis.

Animals↗
PubMed1993

Time-course of recovery of atrial contraction after cardioversion of chronic atrial fibrillation.

We aimed to study the time-course of recovery of atrial contraction after cardioversion of chronic atrial fibrillation (duration of more than 3 months) to sinus rhythm. Using M-mode, two-dimensional and pulsed Doppler echocardiography, we determined left atrial (LA) and ventricular (LV) dimensions, peak velocities, and velocity-time integrals of early and atrial filling velocity-time profiles in both LV and right ventricular (RV) inflows (peak E and peak A, Ea and Aa). Results of the LA and LV functions in seven elderly patients (an initial study group) were as follows. The extent of the LA dimensional reduction resulting from atrial contraction was significantly increased up to 5-8 weeks compared with values 0-1 day after cardioversion [from 1.3 +/- 0.8 (mean +/- SD) mm to 3.9 +/- 1.1, P < 0.01]. In conjunction with the progressive increase in peak A, the ratio of peak E to peak A (peak E/A) was significantly decreased and reached a plateau at 5-8 weeks (from 1.93 +/- 0.59 to 0.67 +/- 0.11, P < 0.01). LV fractional shortening was increased significantly 5-8 weeks after cardioversion (from 0.20 +/- 0.06 to 0.29 +/- 0.05, P < 0.01). Since a large part of the improvement in LA contraction was expected to occur in an early stage after cardioversion, we studied eight additional patients more frequently in the early stage (an additional study group). Furthermore, we studied the time course of LA and right atrial (RA) contractions.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

Growth potential after root replacement of the right and left ventricular outflow tracts.

A successful operation for acute and severe aortic regurgitation after balloon valvuloplasty together with mitral regurgitation is described in a 9-month-old infant. Aortic root replacement was performed using a pulmonary autograft, while the right ventricular outflow tract was reconstructed with an interposed left atrial appendage posteriorly and a heterologous pericardial patch anteriorly. Mitral valve reconstruction was also effectively accomplished. This combination of right and left ventricular outflow tract reconstruction has a good potential for growth and may provide a solution for the future in infants.

Aorta, Thoracic↗
PubMed1993

Acute effects of conventional oral dose of disopyramide on left atrial and ventricular functions.

Disopyramide, an antiarrhythmic drug, is known to impair cardiac function, but acute cardiac effects of conventional oral dose of disopyramide are not well known. To examine the extent of acute cardiac effects of daily oral dose of disopyramide, we gave 150 mg of disopyramide to thirteen patients with normal or impaired cardiac function, and observed cardiac function on an hourly basis for 3 hours after baseline period. The serum level of disopyramide reached a therapeutic level (2.0-5.0 micrograms/ml) mostly 1 hour after administration. Doppler-echocardiographically determined left ventricular ejection fraction, and the ratio of the peak early filling velocity to the peak atrial filling velocity in left ventricular inflow velocity remained unchanged throughout the experimental period. Other hemodynamic variables, such as blood pressure and heart rate remained unchanged. We conclude that daily oral dose of disopyramide appears to have no significant effects on cardiac function after administration. Disopyramide seems to be safe and may not be necessarily withheld from patients who need it, when hemodynamic variables are to be measured.

Adult↗