Biomedical subjects

T Akasaka

Publications and source records attributed to T Akasaka.

287 records · Page 16Linked to original sources

PubMedDate not supplied

Phasic coronary flow characteristics in patients with hypertrophic cardiomyopathy: a study by coronary Doppler catheter.

Abnormal patterns of coronary flow velocity have been observed in patients with symmetric left ventricular hypertrophy in conditions such as aortic stenosis and systemic hypertension. However, phasic coronary flow characteristics have not been investigated in patients with asymmetric left ventricular hypertrophy in hypertrophic cardiomyopathy. The purpose of this study was to assess phasic coronary flow characteristics and their relation to echocardiographic and hemodynamic parameters in patients with hypertrophic cardiomyopathy. Coronary flow velocity was recorded in the left anterior descending artery with a 20 MHz Doppler catheter in eight patients with hypertrophic nonobstructive cardiomyopathy and eight control subjects with normal coronary arteries. Flow reversals observed in systole in all patients with hypertrophic cardiomyopathy, and the time velocity integrals of systolic flow were significantly smaller in patients with hypertrophic cardiomyopathy than in control subjects (-1.5 +/- 1.7 versus 4.3 +/- 1.2 cm; p < 0.01). The time from the beginning of diastole to peak diastolic velocity corrected by the square root of R-R interval (square root of RR) was prolonged significantly, and the velocity half-time from peak diastolic velocity corrected by square root of RR was shorter in the patients with hypertrophic cardiomyopathy compared with those in the control subjects (6.8 +/- 2.0 msec versus 4.0 +/- 0.6 msec [p < 0.01] and 9.2 +/- 4.9 msec versus 13.9 +/- 2.0 msec [p < 0.05], respectively). Peak velocity and time velocity integral of flow reversal showed significant correlations with anterior ventricular septal thickness (y = -0.5x + 13.5, r = 0.8, and p < 0.01; y = -1.3 +/- 16.8, r = 0.8, and p = 0.024, respectively), the septal/free wall thickness ratio (y = -0.1x + 1.1, r = 0.8, and p < 0.01; y = -0.2x + 1.4, r = 0.9, and p < 0.01, respectively), and the degree of narrowing of the first septal perforator arteries (y = 1.9x + 91.6, r = 0.8, and p = 0.012; y = 6.1x + 80.6, r = 0.9, and p < 0.01, respectively). In conclusion, flow reversal in systole and slow acceleration and rapid deceleration in diastole were characteristics in patients with hypertrophic cardiomyopathy. Flow reversal might be related to the degree of left ventricular asymmetry and compression of the septal perforator arteries.

Blood Flow Velocity↗

PubMedDate not supplied

Systolic coronary flow reversal and abnormal diastolic flow patterns in patients with aortic stenosis: assessment with an intracoronary Doppler catheter.

Decreased left ventricular coronary flow reserve has been reported in patients with normal coronary arteries and left ventricular hypertrophy in association with aortic stenosis. However, phasic coronary flow characteristics have not been analyzed in detail in similar patients. The purpose of this study is to assess phasic coronary flow characteristics and their relation to hemodynamic parameters in patients with aortic stenosis. Coronary flow velocities were recorded in the left anterior descending artery with a 20 MHz Doppler catheter in nine patients with aortic stenosis and nine control subjects with normal coronary arteries. Patient aortic valve area ranged from 0.34 to 0.51 cm2. Flow reversal was observed in systole in all patients with aortic stenosis, and time velocity integrals of systolic flow were significantly smaller in patients with aortic stenosis than in controls (-0.3 +/- 2.3 vs 4.0 +/- 1.1 cm, p < 0.01). The time to peak diastolic velocity corrected by square root R-R interval was prolonged and the velocity half-time from peak diastolic velocity corrected by square root R-R interval was shorter in patients with aortic stenosis than in controls (5.3 +/- 1.1 vs 4.0 +/- 0.5, p < 0.01, 8.0 +/- 2.6 vs 13.0 +/- 3.3, p < 0.01, respectively). Peak velocity and time velocity integral of flow reversal showed significant correlations with mean pressure gradient across the aortic valve (y = 1.3x + 37.3, r = 0.72, p = 0.03, y = 11.3x + 41.2, r = 0.81, p < 0.01, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMedDate not supplied

Improved transvalvular continuous-wave Doppler signal intensity after intravenous Albunex injection in patients with prosthetic aortic valves.

UNLABELLED: A lung-crossing contrast agent, sonicated albumin (Albunex), has been reported to enhance left-sided Doppler signals in patients with native valvular diseases. The purpose of this study was to clarify the ability of Albunex to enhance transvalvular Doppler signals in patients with prosthetic aortic valves. Forty-five consecutive patients were studied after they underwent aortic valve replacement. Transvalvular flow signals were recorded from the apical long-axis view with the use of continuous-wave Doppler echocardiography before and after intravenous injection of Albunex (0.04 to 0.08 ml/kg). Continuous-wave Doppler signal quality was graded as follows: 1, none; 2, poor; 3, suboptimal; and 4, optimal. RESULTS: Grade 4 continuous-wave Doppler signal could be detected in 64% of the cases (29 of 45). After contrast injection, continuous-wave Doppler signal quality improved in all, and grade 4 continuous-wave Doppler signal could be detected in 93% (0.04 ml/kg) and 100% (0.08 ml/kg), respectively. The transvalvular maximal velocities derived from contrast-enhanced, continuous-wave Doppler signals were well correlated with the highest available unenhanced. Doppler maximal velocities (y = 0.90x + 0.27, r = 0.93, p < 0.01, standard error of estimate = 0.08 m/sec). CONCLUSION: Intravenous Albunex injection improves transvalvular continuous-wave Doppler signal intensity in patients with prosthetic aortic valves.

Albumins↗

PubMedDate not supplied

Transformation from block-type to graft-type oligonucleotide-glycopolymer conjugates by self-organization with half-sliding complementary oligonucleotides and their lectin recognition.

Block-type oligonucleotide-glycopolymer conjugates bearing alpha-mannosides and beta-galactosides were prepared by coupling 5'-thiol-modified oligonucleotides with iodoacetamidated glycopolymers that were synthesized by telomerization. The conjugates minimally affected the DNA conformation and melting behavior of the duplex. Their self-organization via hybridization with the half-sliding complementary oligonucleotides produced graft-type conjugates or macromolecular gapped DNA duplexes grafted with glycopolymers at regular intervals, which was confirmed using size exclusion chromatography and electrophoresis. The binding affinity of block-type and self-organized graft-type conjugates to lectins was investigated using fluorometry. The affinity of the graft-type duplex assembly bearing mannosides to Con A was approximately 2 times stronger than that of block-type single-stranded or double-stranded conjugates with full complementary oligonucleotides. The organization strategy of DNA-glycopolymer conjugates might be useful for constructing novel glyco-clusters and also for developing a new methodology for gene therapy.

Lectins↗

PubMedDate not supplied

Facile synthesis of stable and lectin-recognizable DNA-carbohydrate conjugates via diazo coupling.

Stable and lectin-recognizable DNA-carbohydrate conjugates were prepared by diazo coupling of lactose and cellobiose derivatives to fragmented salmon testes DNA. The diazo coupling is suggested to take place selectively to guanine bases since the amount of lactose moiety introduced was directly proportional to the G content of various DNAs with different G contents. According to the CD spectra, the conjugates bearing carbohydrate less than 25% content kept a typical B-type conformation similar to native DNA. The conjugates possessed higher melting temperature and stronger nuclease resistance both to exo- and endonucleases than native DNA. Gel shift assay and fluorescence binding assay showed that the DNA-lactose conjugates were specifically bound to galactose-specific lectin RCA(120) with strong binding affinity (Ka = 10(4)-10(5) M(-1)) due to glycoside cluster effect. This facile method will be a useful protocol of molecular design for cell-targeted gene therapy.

Animals↗

PubMedDate not supplied

Correction of tetralogy of Fallot accompanied by malignant hyperthermia. Case report.

A 5-year-old girl susceptible to malignant hyperthermia underwent total repair of tetralogy of Fallot. The initial operation was canceled because of abrupt hyperthermia and metabolic acidosis of unknown cause. Dantrolene was given orally as preoperative treatment and administered intermittently during surgery. Postoperative hyperthermic crisis was successfully treated with intravenous dantrolene combined with surface cooling, gastric tube irrigation with cold saline, and alcohol vaporization.

Child, Preschool↗

PubMedDate not supplied

Successful surgical treatment of subaortic stenosis caused by an accessory mitral valve.

A 22-month-old boy with subaortic stenosis was found to have relatively mature mitral valve tissue beneath the aortic valve, associated with a hypertrophic and prominent interventricular septum. This tissue caused obstruction of the left ventricular outflow tract and resulted in a pressure gradient of 70 mmHg between the aorta and the left ventricle. Surgical treatment was successfully performed to excise the tissue and part of the hypertrophic ventricular septum. Results of microscopic examination of the resected specimen are shown and discussed.

Aortic Valve Stenosis↗

PubMedDate not supplied

Aneurysm of the left subclavian artery associated with Turner's syndrome. Successful surgical treatment.

An unusual case of a 38-year-old woman with Turner's syndrome associated with aneurysmal dilation of the left subclavian artery is presented. Aortography revealed a fusiform aneurysm in the proximal segment of the left subclavian artery, which was as long as 6 cm. The diagnosis of Turner's syndrome was postoperatively confirmed by chromosomal study, which showed 45X0. The aneurysm was successfully removed and reconstruction was done by interposition of a woven Dacron graft, 8 mm in diameter and 6 cm in length, between the thoracic aorta and subclavian artery just proximal to the thoracic outlet. Microscopic findings of the resected tissue of the subclavian artery revealed deposition of acid mucopolysaccharide in the intima and media.

Adult↗

PubMedDate not supplied

The biodistribution and metabolic fate of inhaled 11C-octanal in the rat after acute exposure.

Rats were nose exposed to an atmosphere containing 11.4 ppm of 11C-octanal for 2 min. Inhaled octanal was absorbed from the lungs in a biphasic manner and the greatest concentration of octanal occurred in most tissues at 5 min. Tissue activities calculated on the basis of the administered dose and on the radiolabel retained until the animal was killed indicated a redistribution of the radiolabel as metabolic products after 20 min. The labeled carbon was eliminated in a biphasic manner as 11CO2, which accounted for essentially all of the activity lost by the exposed rats.

Aldehydes↗

PubMedDate not supplied

Surgical treatment of tetralogy of Fallot associated with congenital tricuspid insufficiency. A report of two cases.

Among the congenital anomalies associated with tetralogy of Fallot, tricuspid insufficiency is rare. In two children with tetralogy of Fallot associated with congenital tricuspid insufficiency, one due to elongation of the anterior papillary muscle and resultant redundancy of the anterior cusp of the tricuspid valve and another due to dysplasia of the tricuspid valve, both tetralogy of Fallot and tricuspid insufficiency were corrected simultaneously with success. The etiologic factors, clinical manifestations and surgical implications of this combination of anomalies are discussed. It is emphasized that tricuspid regurgitation must be repaired simultaneously in order to avoid low cardiac output syndrome in the case of tetralogy of Fallot associated with tricuspid regurgitation, particularly in which pulmonary regurgitation might occur after relief of the outflow tract obstruction.

Female↗

PubMedDate not supplied

[Effects of infarcted myocardium on coronary flow reserve: a study by transesophageal Doppler echocardiography].

Myocardial disorder or microvascular disorder can cause impairment of coronary flow reserve in patients without epicardial coronary artery stenosis. This study investigated whether infarcted myocardium influences the coronary flow reserve using transesophageal echocardiography. The coronary flow reserve was examined in 15 patients with anterior myocardial infarction without residual coronary artery stenosis in the chronic phase. The patients underwent 201Tl scintigraphy and were classified into two groups. Group I included six patients without salvaged myocardium and group II included nine patients with salvaged myocardium. The coronary blood flow velocity at the proximal part of the left anterior descending coronary artery (LAD) was evaluated by transesophageal echocardiography before and after dipyridamole administration (0.56 mg/kg/4 min). The ratios of the diastolic peak and mean velocities at hyperemia versus baseline were used as indices of coronary flow reserve (P-CFR and M-CFR, respectively). P-CFR and M-CFR were 1.7 +/- 0.3 and 1.5 +/- 0.4 in group I, and 2.9 +/- 0.5 and 2.7 +/- 0.6 in group II, respectively. Control subjects (n = 7) had P-CFR and M-CFR of 3.8 +/- 0.9 and 3.9 +/- 1.7, respectively. Coronary flow reserve decreased in patients with myocardial infarction, especially in patients without salvaged myocardium in the infarcted area. Infarcted myocardium has an important influence on coronary flow reserve, and transesophageal echocardiography is useful for evaluating coronary flow reserve.

Blood Flow Velocity↗

PubMedDate not supplied

[Usefulness and limitations of dobutamine stress echocardiography for detection of coronary artery disease].

The value of dobutamine stress echocardiography for detecting coronary artery disease was evaluated in 67 patients with normal left ventricular wall motion at rest who also underwent quantitative angiography. The overall sensitivity and specificity of dobutamine stress echocardiography for detecting coronary artery disease were 83% and 70%, respectively. The sensitivities for detecting multivessel disease and single vessel disease were 92% and 76%, respectively. The sensitivity of dobutamine stress echocardiography was 91% in patients treated without beta-blocker, and 70% in patients treated with beta-blocker (p < 0.001). The relatively low peak heart rate during dobutamine infusion in patients treated with beta-blocker seems to affect the sensitivity of dobutamine stress echocardiography. There were no severe complications during dobutamine infusion. Dobutamine stress echocardiography is a safe and accurate method for detecting coronary artery disease. However, an additional technique to increase peak heart rate in patients treated with beta-blocker such as injection of atropin should be considered.

Angiography, Digital Subtraction↗

PubMedDate not supplied

[Residual, recurrent mitral regurgitation after mitral valve reconstruction: differences in lesion and operation method].

Patients developing residual or recurrent mitral regurgitation (MR) increased to moderate or severe grade after mitral valve reconstruction for MR were investigated by correlating the lesion and operation method with the echocardiographic course of postoperative MR. Postoperative moderate or severe grade MR [more than 4.0 cm2 color Doppler flow area on postoperative transesophageal echocardiography (TEE)] occurred in 21 of 80 mitral valve reconstruction patients. If residual MR caused more than 2.0 cm2 color Doppler flow area on intraoperative TEE, the MR increased to moderate or severe grade during the follow-up period. Postoperative moderate or severe MR occurred more frequently in lesions of the anterior mitral leaflet than the posterior mitral leaflet (45.8% vs 6.5%, p < 0.001), and in elongated chordae than in torn chordae (52.9% vs 14.3%, p < 0.005). Chordal shortening for elongated chordae could correct MR at operation but MR recurred and increased gradually to moderate or severe grade in half of these cases. Chordal reconstruction with polytetrafluorethylene suture is expected to achieve better results than chordal shortening. The causes of postoperative MR could usually be identified by comparative investigation of echocardiographic course, lesion, and operation method. Postoperative moderate or severe MR occurs more often in lesions of the anterior mitral leaflet or cases of elongated chordae. Residual MR should be suppressed to less than 2.0 cm2 color Doppler flow area on intraoperative TEE.

Aged↗

PubMedDate not supplied

[Improvement of transthoracic pulsed Doppler imaging of pulmonary venous flow by intravenous injection of sonicated albumin].

Enhancement of pulmonary venous Doppler flow signals by intravenous injection of sonicated albumin was evaluated in 200 patients. Baseline pulsed Doppler signals were strong in 153 (77%) patients and weak in 47 patients. After injection of sonicated albumin, adequate pulsed Doppler flow signals were recorded in 44 (94%) of the 47 patients. Pulsed Doppler recordings could therefore achieve quantitative analysis in 197 patients (98%, p < 0.01). Signals were enhanced in proportion to the sonicated albumin dose (p < 0.01). No remarkable symptoms or complications were seen during and after examinations. Intravenous sonicated albumin improves transthoracic pulsed Doppler imaging of pulmonary venous flow. This simple and safe technique will obviate transesophageal recordings of pulmonary venous flow in adult patients and facilitate further studies of its diagnostic and monitoring value.

Albumins↗

PubMedDate not supplied

[Relationship between early peaking of serum myosin light chain 1 level and washout phenomenon of creatine kinase in acute myocardial infarction].

To investigate the serum levels of myosin light chain 1 (MLC1) during the acute phase of myocardial infarction, the MLC1 and creatine kinase (CK) levels were measured in samples from 59 consecutive patients with acute myocardial infarction. The serum concentration of MLC1 increased rapidly, reaching an early peak in 22 of the 59 patients (the MLP + group). Fifteen patients showed rapid increases in MLC1 levels without an early peak (the MLP - group). Serum MLC1 levels remained within normal limits (the MLN group) 10 hours after the onset of symptoms in the remaining 22 patients (but in eight of these serum MLC1 levels were abnormal 16-39 hours after the onset of symptoms). Serum level curves of CK showed a single episode of acute myocardial infarction in all patients. The patterns of MLC1 levels correlated with the washout phenomenon of CK (p < 0.001) and the maximum MLC1 level (p < 0.05). The ratio of serum MLC1 level during the early phase to the maximum level (EMR) decreased in the order of groups MLP+, MLP-, MLN (0.54 +/- 0.28, 0.31 +/- 0.22, 0.13 +/- 0.09, respectively). The EMR was correlated with the washout phenomenon of CK (p < 0.001), but not with the maximum MLC1 level which might reflect the size of the infarction. The patterns of neither MLC1 nor EMR were correlated with the administration of urokinase or the patency of the infarct-related artery at the early phase (within 10 hours of onset).(ABSTRACT TRUNCATED AT 250 WORDS)

Creatine Kinase↗

PubMedDate not supplied

[Change in mitral valve area after percutaneous transvenous mitral commissurotomy: prediction of mitral valve restenosis].

Factors indicating changes in mitral valve area after single-balloon percutaneous transvenous mitral commissurotomy (PTMC) were evaluated in 53 patients receiving PTMC by follow up for 3-48 months (mean 18 +/- 12 months) using serial transthoracic echocardiography to measure mitral valve area by planimetry. The echocardiographic scores of the mitral commissures and mitral valve, and other clinical variables were assessed. Mitral valve area showed an immediate increase from 1.1 +/- 0.3 to 1.8 +/- 0.3 cm2 (p < 0.01). There was a small but significant decrease in mitral valve area at follow-up to 1.6 +/- 0.4 cm2 (p < 0.01). Restenosis (a decrease in mitral valve area of more than 25% from immediately after PTMC to follow-up) occurred in nine patients (17%). There was no significant correlation between clinical or echocardiographic features and an increase in mitral valve area immediately after PTMC. The total echocardiographic score of the mitral commissures correlated with the decrease in mitral valve area at follow-up (r = 0.42, p = 0.002). Multiple regression analysis showed the total echocardiographic score of the mitral commissures was the best indicator of a decrease in mitral valve area at follow-up (p = 0.0059). Six of nine patients with restenosis had a commissure score of more than 3, while only five of 44 patients without restenosis had a commissure score of more than 3 (p < 0.01). Mitral valve area increases significantly immediately after PTMC, and decreases significantly at follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMedDate not supplied

Left ventricular assist device support of medically unresponsive pulmonary hypertension and aortic insufficiency.

Most centers consider medically unresponsive pulmonary hypertension an absolute contraindication to orthotopic cardiac transplantation because the alternative surgical therapy, heterotopic graft placement, is associated with decreased survival, although most patients normalize their pulmonary hemodynamics postoperatively. Orthotopic transplantation in patients with elevated, but responsive pulmonary pressures, also is associated with an increased operative mortality rate and decreased long-term survival. The authors present the case of a patient with medically unresponsive pulmonary hypertension who was mechanically supported in an effort to improve his orthotopic transplant candidacy and decrease his risk. After informed consent, a HeartMate left ventricular assist device (LVAD) was inserted and the pulmonary hemodynamic response was monitored. Immediately before LVAD insertion, the pulmonary artery pressure (PA) was 74/28 mmHg with a transpulmonary gradient (TPG) of 28 mmHg, and a pulmonary vascular resistance (PVR) of 6.6 Wood units, despite prolonged dobutamine, milrinone, and prostaglandin E1 infusions. After 10 weeks of LVAD support, pressure and resistance improved; pulmonary artery pressure was 28/15 mmHg, transpulmonary gradient was 15 mmHg, and pulmonary vascular resistance was 2.8 Wood units. This patient subsequently underwent an uneventful orthotopic heart transplant. At 1 year after transplantation, pulmonary artery hemodynamics were normal (PA 34/14 mmHg, TPG at 8 mmHg, and PVR at 1.5 Wood units). The authors recommend the consideration of LVAD placement in patients with medically unresponsive pulmonary artery hypertension to assess PA responsiveness and improve the patient's orthotopic cardiac transplant candidacy and decrease the operative risk. However, several weeks may be needed for normalization of pressure and resistance.

Adult↗