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Biomedical subjects

S Beppu

Publications and source records attributed to S Beppu.

138 records · Page 8Linked to original sources
PubMedDate not supplied

Effect of pericardium on left ventricular early filling assessed by pulsed Doppler echocardiography.

Pericardial effect on left ventricular early filling was studied in six dogs by use of pulsed Doppler echocardiography. Rapid dextran infusion was used to manipulate left atrial pressure. Left ventricular peak early filling velocities before and after pericardiectomy were measured at different levels of left atrial pressure with right atrial and left ventricular pressures. Peak early filling velocity correlated with mean left atrial pressure before and after pericardiectomy. Before pericardiectomy, when mean right atrial pressure exceeded 12 mm Hg, further increase of the velocity was not observed in spite of volume loading. After pericardiectomy, peak early filling velocity became higher and the slope of the relation line between mean left atrial pressure and the velocity became steeper than before pericardiectomy. When the filling pressure was denoted by the transmural mean left atrial pressure, the points on the relation line before pericardiectomy fell along the relation line after pericardiectomy. We conclude the pericardium exerts an external constraint on left ventricular early filling. Therefore we should not consider the absolute but the transmural filling pressure when estimating left ventricular early diastolic function with use of Doppler-derived left ventricular early filling velocity.

Animals↗
PubMedDate not supplied

Early diagnosis of stuck Starr-Edwards disc valve in mitral position: inconstant and interrupted mitral regurgitation.

The patient was a 40-year-old man with Starr-Edwards disc valve for 21 years without symptoms. Newly developed systolic murmur at the apex was noticed at the monthly medical examination. Doppler color flow mapping indicated severe mitral regurgitation. However, the appearance of mitral regurgitation was not constant. Continuous wave Doppler recording indicated that some of the mitral regurgitations were abruptly terminated at early or mid systole with the disc closing signal. Mitral regurgitation was observed only at bradycardia and on the left lateral position. Cardiac surgery demonstrated no abnormality on the disc valve except small sulci on the rim of the disc. When the disc was tilted in the cage, it was stuck and did not move. Echocardiography was useful in detecting the early stage of stuck artificial valve that might be fatal in the mitral position.

Adult↗
PubMedDate not supplied

Prolonged myocardial contrast echocardiography via peripheral venous administration of QW3600 injection (EchoGen): its efficacy and side effects.

We examined the efficacy and side effects of a newly developed contrast agent for intravenous myocardial contrast echocardiography, QW3600 Injection (EchoGen; Sonus Pharmaceuticals, Bothell, Wash.). Doses of 0.1, 0.2, 0.5, and 0.8 ml/kg of this agent were administered intravenously to 8 open-chested dogs. The left ventricular (LV) myocardium was uniformly well opacified for the 0.5 and 0.8 ml/kg doses, for which the peak intensity was an average of 40 gray levels above the baseline intensity. The myocardial opacification persisted even after the contrast echo intensity in the LV cavity had decreased. After ligation of the coronary artery, the area at risk was clearly delineated by the same doses. The agent emulsion and dissolved bubbles were examined microscopically in vitro and in vivo to elucidate the mechanism of prolonged opacification. A microscopic investigation of the mesenteric vessels of a rat indicated that bubbles had formed, growing as large as 30 to 50 microm [corrected] in diameter. The hemodynamic parameters did not change at low doses (0.1 and 0.2 ml/kg), but the systemic pressure fell and the arterial blood oxygen saturation decreased at high doses (0.5 and 0.8 ml/kg). EchoGen provides prolonged contrast for myocardial contrast echocardiography via peripheral venous administration, although the hemodynamic parameters deteriorate at high doses.

Animals↗
PubMedDate not supplied

Practical assessment of natural heart function using echocardiography in mechanically assisted patients.

Left ventricular assist systems (LVAS) can maintain the systemic circulation of patients with acute, profound heart failure. The assessment of natural heart (NH) function, however, is difficult in the clinical setting. The authors introduced a new index, heart rate-corrected ejection time/left atrial pressure (ETc/LAP) using echocardiography to evaluate NH function in 15 adult patients on the original LVAS for greater than 2 days. Bypass flow (BF) was gradually decreased according to the recovery of NH. Five patients were weaned from LVAS within 15 days, and LV function was well maintained (Group 1). Another six patients were weaned from LVAS within 21 days but died within 2 weeks (Group 2). The other four patients died on LVAS without recovery of NH (Group 3). In Group 1 patients, ejection time/pre-ejection period (ET/PEP) with LVAS assist increased continuously. In Groups 2 and 3, ET/PEP increased slowly and reached a plateau at approximately 10 days or remained low. Group 1 patients reached an ETc/LAP of 35 +/- 10 on LVAS within 7 days. Group 2 and Group 3 patient values were 18 +/- 2 (p less than 0.05) and 9 +/- 6 (p less than 0.01), respectively, on the seventh day. Based on these data, this new index provides an estimate of global NH function and a prediction of the probability of NH recovery.

Adult↗
PubMedDate not supplied

Thrombus in a natural left ventricle during left ventricular assist: another thromboembolic risk factor.

Systemic thromboembolism is one of the serious complications during use of a left ventricular assist system (LVAS). The authors' original LVAS has excellent antithrombogenicity to reduce this risk, but thrombus formation in a natural left ventricle (LV) is another risk factor for systemic embolization. We used our LVAS in 22 patients. Of these, LV wall motion was studied in 15, and a smoke-like echo disclosed thrombus in the LV in eight. When LVAS sufficiently supported the systemic circulation, LV wall motion was irregular upon closure of the aortic valve. Upon recovery of LV function and decrease of LVAS flow, the smoke-like echo diminished and LV thrombus decreased in one, but LV thrombus remained unchanged or increased in seven. Systemic administration of antithrombotic agents had an unclear effect. Seven of eight patients with LV thrombus on echo died during or after LVAS. In these seven, a high incidence of LV thrombus (71%), and systemic embolism to the brain (29%) or kidney (86%), were revealed at necropsy. We subsequently used local heparinization to prevent LV thrombus formation. One patient with a smoke-like echo had no evidence of LV thrombus or systemic embolism. During LV assist, careful management of the LVAS, and intra-LV heparinization should be considered to reduce the risk of thrombus formation in the natural LV.

Adult↗
PubMedDate not supplied

Clinical features of familial hypercholesterolemia.

The clinical consequences of familial hypercholesterolemia (FH) result from its metabolic peculiarities that persist from very early childhood, leading to the accumulation of cholesterol in the form of xanthomas in skin and tendons and atheromatous lesions in the arterial wall, in particular, in the aorta and the stem of coronary arteries. Plasma cholesterol concentration markedly increases during the suckling period, soon attaining a level near 1000 mg/dl in homozygotes and 200 to 400 mg/dl in heterozygotes. By age 50, about 80% of FH males suffer from ischemic heart diseases, while only 20% to 30% of the females are moderately affected by coronary atherosclerosis. In addition to the low density lipoprotein (LDL) cholesterol level, higher triglyceride and lower high density lipoprotein (HDL) cholesterol levels correlate with an increased risk of ischemic heart diseases. A very important problem is that most of these patients do not feel themselves to be seriously ill until a severe myocardial infarction (often leading to sudden death) takes place during the third to fifth decades of life. Among the different types of receptor mutations, the incidence of ischemic heart diseases was much higher and more extensive among patients with the receptor-negative type than among those with the receptor-defective type with a residual receptor activity.

Age Factors↗
PubMedDate not supplied

Midazolam and somatosensory evoked potentials.

The effect of midazolam, a water-soluble benzodiazepine, on the somatosensory evoked potentials (SEPs) following strong electrical stimulation of the upper lip, was investigated in Wistar albino rats. SEPs were recorded from the surface of the skull in the contralateral temporal area. A computer was used to obtain the averaged SEPs. The rats received intraperitoneal dosages of 1.25, 2.5, or 5.0 mg/kg of midazolam, or physiological saline. Relative amplitudes of the P(1)N(1) wave were reduced significantly after midazolam injection. Amplitude recovered to the control level about 120 min after the injection in the 1.25 mg/kg group. In 2.5 and 5.0 mg/kg groups, midazolam-induced suppression did not recover within 120 min. No significant differences were found in the latencies of P(1) and N(1) before and after midazolam injection. It is suggested that midazolam has a mild analgesic effect due to central suppression of the pain perception following noxious stimuli.

Animals↗
PubMedDate not supplied

Midazolam does not affect the field potentials in the caudal part of the spinal trigeminal nucleus.

The effect of midazolam on the field potentials (FPs) in the caudal part of the spinal trigeminal nucleus following strong electrical stimulation of the upper lip was investigated in Wistar albino rats. The rats received i.p. dosages of 5, 10, or 20 mg/kg midazolam, or physiological saline. Relative amplitudes of the negative deflection were not suppressed after midazolam injection. No significant differences were found in the latencies of the potentials before and after midazolam injection. It is suggested that the main action site of midazolam may be located at a higher level than the spinal trigeminal nucleus.

Animals↗
PubMedDate not supplied

Sedative effects and cardiorespiratory influences of intravenous flunitrazepam premedication.

Sedative effects and the influence on cardiorespiratory functions of flunitrazepam, 0.015 mg/kg intravenously, were studied in 13 healthy adult volunteers. Immediately after administration, 12 of the 13 subjects responded when their names were called, while one subject required gentle patting on the shoulder to evoke a response. The scores of EEG and electro-oculogram were decreased. Cardiorespiratory changes were mild and not significant clinically. Anterograde amnesia was remarkable. Equilibrium functions were normal at 180 min postdose. Only one subject complained of pain at injection. It was concluded that intravenous injection of 0.015 mg/kg flunitrazepam was an optimal dose for sedation in healthy adults.

Adult↗
PubMedDate not supplied

[Diagnosis of coronary artery dehiscence and pseudoaneurysm after modified Bentall operation by Doppler color flow imaging: a case report].

This 48-year-old man presented with anterior chest and back pain in 1981. He was treated with replacement of the ascending aorta and aortic valve under a diagnosis of dissection of the ascending aorta with severe aortic regurgitation. He underwent modified Bentall reoperation for the dilation of the aortic root in 1991. Postoperative two-dimensional echocardiography was performed because of sustained atrial flutter. An echo-free space was detected between the aorta graft and aorta wrapping on the short-axis view. Doppler color flow imaging revealed blood flow from the left coronary artery graft into the echo-free space. This leakage was suspected to be the cause of the echo-free space. Transesophageal echocardiography was performed to conform this hypothesis, which revealed blood flow from the left coronary artery graft into the echo-free space in systole and flow into the left coronary artery graft from the echo-free space in diastole.

Anastomosis, Surgical↗
PubMedDate not supplied

[Timing of inflow to the atrium after ventricular contraction and relaxation: effect of atrial wall stiffness].

A stiff atrium is sensitive to even a small change in its volume, causing a rapid change in the caval vein flow. We hypothesized that the onset of caval vein flow may follow immediately after the onset of a ventricular event in a patient with a stiff atrium. The timing of inflow into the right ventricle and into the atrium were examined by Doppler echocardiography in 20 healthy subjects, 12 patients with constrictive pericarditis, and 10 patients with cardiac tamponade. The onset of diastolic flow in the superior vena cave followed 17 +/- 14 msec after the onset of early diastolic filling flow into the right ventricle in constrictive pericarditis patients, which was significantly shorter than 107 +/- 45 msec in the healthy subjects. The onset of systolic flow occurred 178 +/- 46 msec after the peak of the R wave of the electrocardiogram in cardiac tamponade patients, which was significantly longer than 129 +/- 17 msec in healthy subjects. This time was slightly shorter in constrictive pericarditis (103 +/- 21 msec). We conclude that a short time lag from the onset of a ventricular event to the onset of caval flow indications that the right atrium is stiff.

Adult↗