Toluene induces behavioral activation without affecting striatal dopamine metabolism in the rat: behavioral and microdialysis studies

We examined the effects of toluene on the release of dopamine (DA) and its metabolites in rat striatum using microdialysis. Intraperitoneal injection of 800 mg/kg toluene significantly increased motor activity in rats, as did methamphetamine (MAP) (1 mg/kg). However, 800 mg/kg toluene did not affect the extracellular levels of DA, 3,4-dihydroxyphenylacetic acid, homovanillic acid, or 5-hydroxyindoleacetic acid. This is in contrast to MAP, which significantly increased extracellular DA and decreased the extracellular levels of its metabolites. These results suggest that toluene-induced behavioral augmentation may not be associated with alterations in DA or serotonin neurochemistry such as are associated with MAP-induced behavioral augmentation.

Localization of mRNAs of voltage-dependent Ca(2+)-channels: four subtypes of alpha 1- and beta-subunits in developing and mature rat brain

The heterogeneous gene expression for four subtypes of alpha 1 (A,B,C,D)- and beta (beta 1,beta 2,beta 3,beta 4)-subunits of voltage-dependent calcium channels was demonstrated in developing and adult rat brain by in situ hybridization histochemistry. In the adult rat brain the gene expression for A- and B-subtypes was predominant in the cerebellar cortex and hippocampal neuronal layers, with the A-subtype expressed most intensely in the Purkinje cells, while the expression for C- and D-subtypes was predominant in the olfactory mitral and granule cells and the dentate granule cells. The expression of beta 1-mRNA was prominent in the olfactory mitral cells and dentate granule cells whereas that of beta 2-mRNA was evident in the hippocampal neuronal layers and cerebellar Purkinje cells. The expression of beta 3-mRNA was prominent in the olfactory mitral and internal granule cells and medial habenula, whereas that of beta 4-mRNA in the olfactory mitral cells and cerebellar Purkinje and granule cells. Comparison between the expression patterns for individual alpha- and beta-subunits suggests that the beta 4-subunit contributes to P-type channel, whereas the beta 1- and beta 3-subunits contribute respectively to D- and C-subtypes of L-type channels, although dissociation in the expression patterns were also noted in several brain regions. In addition to neuronal populations, the gene expression for the C-subtype of L-type channel was detected at substantial level in glial cells. In developing brains, the genes for the all subtypes of alpha 1- and beta-subunits were expressed in the mantle zones, but not the ventricular zones, of the entire neuraxis and the expression was more or less attenuated during early postnatal periods in most of the brain regions except for the olfactory bulb, hippocampus and cerebellar cortex, suggesting that the Ca(2+)-channels are intimately involved in the neuronal differentiation.

Effects of aging and dietary restriction on activity of monkey serum in promoting fibroblast migration

In order to determine whether serum modified cellular aging in vivo, we previously studied the effects of serum from various mammals of different ages on cell functions such as proliferation and migration, and reported that cell migration was more greatly inhibited by serum from old donors than cell proliferation [1]. Moreover, since dietary restriction has been reported to extend lifespan and slow the aging rate of some animals [2], we wondered whether sera from dietary restricted and control monkeys of various ages might exhibit reduced aging effects on cell migration. When serum from young adult (3-5 years old) monkeys was added to plain medium, the migration of human fetal skin fibroblasts was very strongly inhibited compared to FBS. Surprisingly, sera from adult (6-11 years old) and old (more than 18 years old) monkeys caused significantly less migration-inhibitory activity than serum from young adult monkeys although sera from adult and old monkeys were much more inhibitory to cell migration than FBS. Dietary restriction only caused marginal effects on serum migration-promoting activity in a few monkey groups. The inhibition of cell migration caused by monkey serum was not brought about by cytotoxic effects since monkey serum stimulated cell proliferation as well as fetal bovine serum. These results indicate that the effects of aging on monkey serum migration-promoting activity are much more pronounced than those of dietary restriction.

Stabilized enzymatic reagents for measuring glucose, creatine kinase and gamma-glutamyltransferase with thermostable enzymes from a thermophile, Bacillus stearothermophilus

Stabilized enzymatic reagents for measuring some components in biological fluids have been successfully developed based on two kinds of thermostable enzymes derived from Bacillus stearothermophilus with separation of the reagent into two complementary solutions. The thermostable glucokinase produced was applied to the measurement of glucose and creatine kinase activity, while the alanine dehydrogenase produced was used for the measurement of gamma-glutamyltransferase activity. The enzymatic reagents were also stabilized by developing two separate reagents with an optimum pH for the main reagent components. The stability of the reagents in liquid form was examined at 10 degrees C. It was clearly shown that the reagents for measuring glucose and creatine kinase activity were stable and retained their full capability for accurate measurement in biological fluids for over one year. The alanine dehydrogenase product was stable for at least 40 days.

New isolates of pneumonia virus of mice (PVM) from Japanese rat colonies and their characterization

Two virus strains were isolated from the lungs of athymic rats and mice used as sentinel animals in 2 colonies of laboratory rats in Japan in which antibodies to the pneumonia virus of mice (PVM) had been detected. The new isolates were identified as PVM by the following characteristics: RNA virus, susceptibility to ether treatment, long filamentous viral structure in the cytoplasm of infected cells, and hemagglutinating activity in various erythrocytes, including those of mice and rats. In addition, cross neutralization with the prototype of PVM (No. 15 strain) was observed. This is the first report of the isolation of PVM from laboratory animals in Japan.

[A case of cryptococcal meningoencephalitis with the cerebral superficial cystic lesions detected on magnetic resonance imagings]

The patient was a 35-year-old man with confusional state and headache. Analysis of cerebrospinal fluid (CSF) showed 1,383/mm3 cell count, the protein level of 300mg/dl and glucose level of 42 mg/dl. Cryptococcus neoformans was disclosed by India ink preparation. The cryptococcal antigen test was positive at 1:125 by latex agglutination. The diagnosis of cryptococcal meningoencephalitis was determined. Antifungal treatment with amphotericin B resulted in improvement of neurologic signs, CSF findings and cryptococcal antigen test. But two months later, brain MRI demonstrated low intensity areas on T1 weighted image and high intensity areas on T2 and proton weighted images in the cerebral cortical region. Gd-DTPA MRI showed enhanced areas in the cerebral leptomeninges. It was considered that these MRI lesions corresponded to pseudocysts and Gd-DTPA enhanced lesion indicated dilated vessels or destructed blood-brain barrier. After administration of larger doses of amphotericin B, these lesions on MRI disappeared. It is suggested that brain MRI is useful in diagnosis of cryptococcal meningoencephalitis to detect pseudocysts at the cortical region which may imply the early stage of procrastinating process.

[A case of small cell lung cancer with renal insufficiency effectively treated with oral etoposide administration]

A 74-year-old woman with left-sided heart failure was admitted to our department with abnormal shadow in the right lung. Chest X-P and CT scans showed a tumor shadow measuring 2.5 cm in the right lower lobe and mediastinal lymphnode swelling. Cytological examination of needle biopsy specimen revealed small cell carcinoma (cT1N2M0). Elevations of tumor marker, NSE and CEA were noticed at 11.8 and 12.7 ng/ml, respectively. Considering complications including renal insufficiency and heart failure in the case, 2 courses of oral etoposide (25 mg/body) for 21 consecutive days were performed. The tumor shadow decreased remarkably in size and complete response (CR) was obtained. Side effects were all tolerable. A pharmacokinetic study of etoposide revealed serum etoposide levels of more than 1.0 microgram/ml on day 15. These results suggest that oral etoposide administration is an effective regimen in small cell lung cancer patients associated with renal insufficiency.

[A case of chest wall tumor associated with production of CA125 treated effectively by chemotherapy]

A 61-year-old female was admitted to our hospital because of a mass in right lateral chest wall and chest pain. Chest X-P and CT scans showed a right chest wall tumor and pleural effusion. Biopsy specimen from the chest wall tumor revealed an adenocarcinoma, not a mesothelioma, based on immunohistochemical study. Cancer cells were also detected in pleural effusion. Imaging diagnostic analysis could detect no primary tumor in lung field or other organs. High levels of CA125 were noticed: 9,610 U/ml in serum and 37,600 U/ml in pleural effusion, respectively. Finally, there was a possibility that the chest wall tumor might be a metastatic lesion from undetected ovarian cancers, so three cycles of combined chemotherapy (CDDP+ADM+CPA) were done. CDDP plus OK-432 was also injected two times intrapleurally. After chemotherapy, the chest wall tumor and effusion disappeared and the serum CA125 level decreased to the normal range.

Clinical trial of continuous infusion of 5-fluorouracil using an ambulatory pump for metastatic colorectal cancer

A clinical trial was conducted in order to evaluate the anti-tumor effect and toxicity of a continuous infusion of 5-fluorouracil (5-FU) for metastatic colorectal cancer. Two-hundred and fifty mg/m2/day 5-FU was administered as a continuous infusion through an indwelling central venous catheter with ambulatory pump. Twenty patients with metastatic colorectal cancer which could be measured or evaluated were enrolled in the trial. The objective response rate was 35% (95% confidence interval, 14-56%). The response rates by site were 33% in liver, 17% in lung, 60% in lymph nodes, 50% in adrenal gland and 50% in primary lesion. The major toxicity was stomatitis (50%; grades 2 and 3 on Eastern Cooperative Oncology Group (ECOG) criteria) and hand-foot syndrome (40%; grades 2 and 3 on ECOG criteria). The sequence of toxicity was stomatitis first, followed by hand-foot syndrome. The median cumulative dose of 5-FU from the initiation of therapy to the onset of toxicity was 7125 mg in stomatitis and 17,875 mg in hand-foot syndrome. These toxicities were mild and reversible after a short interruption to the 5-FU infusion. Neither hematological toxicity nor serious catheter-related complications were observed. We concluded that continuous infusion of 5-FU was a feasible treatment for the patient with metastatic colorectal cancer, and manageable on an out-patient basis.

[A case of SLE associated with antiphospholipid syndrome and mitral stenosis]

This case involves a 41-year-old woman with SLE. The patient began having symptoms of arthralgia in 1978 and developed fever, pleuritis and lupus psychosis in 1986. Laboratory exams showed positive antinuclear-antibody, LE-cell phenomenon, hypocomplementemia and lupus anticoagulant. Echo cardiography demonstrated mitral regurgitation and stenosis. She was treated with 50 mg of prednisolone and these manifestations subsided. In 1989, she developed dyspnea on exertion and echo cardiography revealed severe mitral stenosis. Pulmonary infarction was detected by MAA lung scintigraphy. At this time, she was diagnosed as SLE associated with antiphospholipid syndrome (APS). A mitral valvular replacement operation was performed in 1991. Pathological studies of mitral valve demonstrated Libman Sacks endocarditis. APS is known occasionally to complicate with left-sided valvular diseases, mitral stenosis is quite rare in both SLE and APS. This patient reveals a rare case of SLE associated with APS and mitral stenosis. It is suggested that this patient developed mitral stenosis with Libman Sacks endocarditis, associated with the presence of antibody against phospholipids.

[Anti-platelet antibodies in sera from patients with systemic lupus erythematosus by immunoblot analysis]

It has not been clarified that the anti-platelet antibodies are related to thrombocytopenia in systemic lupus erythematosus (SLE). We evaluated the presence of anti-platelet antibodies in sera from patients with SLE using immunoblot analysis. In this study, 19 of 65 cases (29.2%) in SLE had anti-platelet antibodies in their sera, whereas no anti-platelet antibodies were detected in 16 cases of rheumatoid arthritis, 16 cases of progressive systemic sclerosis, 2 cases of polymyositis-dermatomyositis and 10 healthy controls. Six bands of 200 kDa, 140 kDa, 120 kDa, 95 kDa, 80 kDa and 65 kDa molecular weight were detected using immunoblot analysis. The platelet antibodies to 95 kDa and 80 kDa proteins were frequently detected in 12.3% and 16.9% respectively of SLE. These 2 antibodies were absorbed with the platelet pellet derived from healthy person. Therefore, it was suggested that the antibodies to 90 kDa and 80 kDa platelet antigens were specific to platelet membrane protein. Although we could not find any correlation between clinical and laboratory manifestations of SLE and these platelet antibodies, these antiplatelet antibodies were specifically detected in sera from patients with SLE by immunoblot analysis.

Intraventricular dispersion of early diastolic filling: a new marker of left ventricular diastolic dysfunction

Mitral flow velocity patterns are frequently "normalized" by the alteration in the loading condition even in the presence of left ventricular (LV) diastolic dysfunction. In addition, a simple index, the ratio of mitral peak early diastolic flow velocity to mitral peak flow velocity at atrial contraction, is not obtainable in patients with atrial fibrillation (Af). Thus these limitations hamper the value of analyzing the mitral flow velocity pattern in the assessment of abnormal LV diastolic characteristics. This study was designed to elucidate the hypothesis that peak early diastolic flow velocity decreases progressively from the base to the apex in patients with LV diastolic dysfunction. Regional diastolic flow velocity patterns at 1, 2, or 3 cm from the mitral tip toward the apex were simultaneously recorded with the mitral flow velocity pattern by using multigate pulsed Doppler echocardiography in 42 subjects with normal LV function (31 normal volunteers and 11 patients with Af only), 17 patients with hypertensive heart disease, and 22 patients with dilated cardiomyopathy. In the normal subjects early diastolic flow velocity at the mitral tip was maintained at the positions 1 to 3 cm away from the tip into the LV cavity. In contrast, regional peak early diastolic flow velocity progressively decreased toward the apex in patients with hypertensive heart disease and dilated cardiomyopathy. These findings were observed even in patients with a normalized mitral flow velocity pattern or those with Af. Thus the assessment of the intraventricular decrease in peak early diastolic flow velocity may be useful in detecting LV diastolic dysfunction, particularly in patients with Af or a "normalized" mitral flow velocity pattern.

Digital subtraction high-frame-rate echocardiography in detecting delayed onset of regional left ventricular relaxation in ischemic heart disease

BACKGROUND

Because left ventricular (LV) diastolic function is impaired before systolic function in patients with ischemic heart disease and because ischemic heart disease is constituted of regional rather than global abnormalities of the left ventricle, measures of LV regional diastolic dysfunction, if possible, should provide the most sensitive assessment of the coronary involved region. The objectives of this study are to clarify whether high-frame-rate two-dimensional echocardiography, combined with digital subtraction image processing, may be used to visualize regional LV relaxation abnormalities in patients with ischemic heart disease and to clarify whether this technique provides a measure for the noninvasive assessment of the coronary involved region.

METHOD AND RESULTS

In 30 normal subjects and 59 patients with ischemic heart disease, two-dimensional echocardiograms obtained at a rate of 60 frames per second were provided on line for digital subtraction analysis, with which digitized images were continuously subtracted on a frame-by-frame basis. The subtracted images were analyzed to determine the onset of the segmental outward motion of the LV wall in early diastole in each of 16 segments per subject. Regional relaxation index, defined as the interval from the second heart sound to the onset of outward wall motion, was significantly prolonged in the coronary involved segments compared with the normal segments (36.3 +/- 18.0 versus 101.2 +/- 34.0 ms, P < .01). The prolongation in the regional relaxation index was observed even in the coronary involved segments without reduction in systolic wall motion. When a cutoff level of 50.0 ms was used, coronary involved segments could be distinguished from normal or border segments with a sensitivity of 92% and a specificity of 81%.

CONCLUSIONS

Digital subtraction high-frame-rate echocardiography may be used to visualize regional LV relaxation abnormalities in patients with ischemic heart disease. The time interval from the second heart sound to the onset of the segmental outward motion of the LV wall (regional relaxation index) obtained with this technique provides a noninvasive and accurate measure for assessing coronary involved regions.

Single-laser three-color immunolabeling of a histological section by laser scanning microscopy: application to senile plaque-related structures in post-mortem human brain tissue

We describe a method for observing three-color immunofluorescence simultaneously in a histological section under a confocal laser scanning microscope. In this study we investigated the spatial relationship of blood vessels, reactive microglia, and amyloid beta-protein (A beta) deposits in post-mortem brain tissue of patients with Alzheimer's disease. HLA-DR was employed as a marker for activated microglia and von Willebrand factor (vWF) as a marker for vascular endothelial cells. HLA-DR was labeled with R-phycoerythrin (R-PE) and vWF with fluorescein isothiocyanate. A beta-protein was immunostained with the tandem conjugate of R-PE and cyanin 5. Three images were obtained serially by scanning a tissue section with a 488-nm laser beam in combination with an appropriate emission filter for each fluorochrome. Overlaying of these three images permitted simultaneous observation of three distinct structures: activated microglia, blood vessels, and A beta deposits. This technique provides an improved way to study the localization of three different antigens in a single tissue section.

Doppler echocardiographic pulmonary venous flow-velocity pattern for assessment of the hemodynamic profile in acute congestive heart failure

The hemodynamic profile of congestive heart failure (CHF) is best described in terms of its two primary sets of hemodynamic parameters, that is, left atrial pressure and cardiac output, each of which has a specific and independently variable hemodynamic cause. To assess whether analysis of the mitral and/or pulmonary venous flow-velocity patterns provides valuable information in the noninvasive assessment of the hemodynamic profile of CHF, these patterns were obtained by using the transthoracic approach in 18 patients with acute CHF with simultaneous measurements of catheter-derived mean pulmonary capillary wedge pressure and thermodilution cardiac index. Measurements were repeated on two occasions in each case: at the acute stage of CHF and 1 to 5 days after treatment. Peak diastolic pulmonary venous forward flow velocity was higher, the ratio of pulmonary venous systolic to diastolic peak forward flow velocity was lower, and the ratio of mitral early diastolic to late diastolic flow velocity was greater in patients with higher mean pulmonary capillary wedge pressure (r = 0.80, n = 36, p < 0.01; r = -0.69, n = 36, p < 0.01; r = 0.71, n = 36, p < 0.01). Peak systolic pulmonary venous forward flow velocity and time-velocity integral of the systolic pulmonary venous flow wave were greater in patients with larger cardiac index (r = 0.80, n = 36, p < 0.01; r = 0.62, n = 36, p < 0.01). In conclusion, two primary sets of hemodynamic parameters, that is, left atrial pressure and cardiac output, can be estimated with Doppler pulmonary venous flow parameters in patients with acute CHF.

CRST syndrome (calcinosis cutis, Raynaud's phenomenon, sclerodactyly, and telangiectasia) associated with autoimmune hepatitis

A case of Raynaud's phenomenon, was complicated with autoimmune hepatitis (AIH) during the clinical course, and subsequently with gangrene of the fingertips caused by CRST syndrome (calcinosis cutis, Raynaud's phenomenon, sclerodactyly and telangiectasia). The presence of anticentromere antibodies is rare in AIH; to date, there has been only one report of a combination of AIH and CRST syndrome. This combination of the two diseases has been identified only in Japan.

Transthoracic Doppler echocardiographic measurements of pulmonary venous flow velocity patterns: comparison with transesophageal measurements

Recently, we and other groups showed that analysis of transthoracic pulmonary venous flow velocity patterns is useful in the estimation of left ventricular diastolic function and left atrial pressure; however, it is unclear whether transthoracic tracings, in contrast to transesophageal tracings, provide reliable quantitation of the abnormal pulmonary venous flow characteristics in patients with and without cardiac disorders. This study was attempted to validate transthoracic pulmonary venous flow measurements by comparing them with transesophageal measurements in eight normal volunteers and 17 patients with a variety of cardiac disorders. Transesophageal and transthoracic measurements of peak diastolic forward flow velocity, the ratio of peak systolic/diastolic forward flow velocities, and the peak reversal flow velocity at atrial contraction sampled in the right upper pulmonary vein showed good correspondence to each other. The flow velocities were higher in the right upper pulmonary vein than in the left upper pulmonary vein. Narrower spectral flow velocity patterns with higher velocities were obtained 1 to 2 cm distal to the orifice in the pulmonary vein than at the orifice. Thus transthoracic measurements of the pulmonary venous flow velocity pattern are feasible and accurate in patients and may be used to assess left ventricular function and hemodynamics as a substitute for transesophageal measurements.

Small depressed cancer of the large bowel: report of three cases

This report describes three patients in whom colonoscopy detected small depressed cancers (without an elevated component) that had invaded the submucosa. They represent 0.4% (3/884) of all patients with invasive cancers and 3% (3/101) of patients with submucosal cancers in the National Cancer Center Hospital between January 1990 and February 1994. This type of cancer may have been overlooked in the past because of its small, flat nature. A slight deformity of the lumen, a faint color change (slightly reddish), and a loss of a vascular network pattern were important colonoscopic findings. Small depressed cancers may follow a different pathway to advanced cancer than polypoid cancers, although both pathways are included in the adenoma-carcinoma sequence. We should be aware of these lesions in our efforts to detect colorectal cancers in the early stage.

Species difference in the resistibility of embryonic fibroblasts against oxygen-induced growth inhibition

The growth of fibroblasts, which were isolated from human, rabbit, rat, mouse, and chick embryos, was inhibited partially under 50% oxygen and nearly completely under 95% oxygen. There was species difference in the resistivity of these cells against oxygen-induced growth inhibition. The extent of the resistivity was in the following order: chick cells > rat cells > human cells > rabbit cells approximately mouse cells. The order of their ability to recover from oxygen-induced growth inhibition was similar to the above order of species. There was also species difference in their antioxidant enzyme activities, including superoxide dismutase, catalase, and glutathione peroxidase activities, and their reduced glutathione concentration. Chick cells, having the highest resistivity against oxygen-induced growth inhibition, were at the lowest activity levels of antioxidant enzymes and at the highest concentration level of reduced glutathione. The species difference in resistivity against oxygen-induced growth inhibition seems to depend on the reduced glutathione concentration, but not on the antioxidant enzyme activities.

Extramedullary plasmacytoma of maxillary sinus with later involvement of the gall bladder and subcutaneous tissues

We recently encountered a patient with extramedullary plasmacytoma (EMP) originating in the maxillary air sinus, who developed subcutaneous tissue and gall bladder involvement 2 years after initial local radiotherapy. Treatment with melphalan, prednisone and interferon led to a rapid and sustained regression of the gall bladder tumour. Complete remission was obtained by subsequent regional radiotherapy to the subcutaneous tumours in the extremities. Progression of plasmacytoma to the hepatobiliary system and subcutaneous tissues is quite rare and the effects of chemo- and radiotherapy on these lesions have not been fully elucidated. This study demonstrated that EMP can be well controlled and complete remission obtained by various therapeutic strategies, even though this tumour develops widespread dissemination.

Validation of transthoracic myocardial ultrasonic tissue characterization: comparison of transthoracic and open-chest measurements of integrated backscatter

To investigate whether myocardial integrated backscatter (IB) can be measured through the chest wall, myocardial IB parameters were measured in five adult mongrel dogs with a newly developed IB imaging system capable of measurements of myocardial IB relative to backscatter from the blood. There was no significant difference in the calibrated myocardial IB between the closed chest and the open chest conditions either in the septum or in the posterior wall if a 2.5- or 3.5-MHz frequency transducer was used. There was no significant difference in the magnitude of cyclic variation in IB between the closed chest and the open chest conditions independent of the frequency of the transducer used. These data suggest that we can accurately measure not only the magnitude of cyclic variation in IB but also the calibrated myocardial IB through the chest wall with a 2.5- or 3.5-MHz frequency transducer. Such data may validate measurements of myocardial IB parameters through the chest wall even in humans.

Pulmonary resection for metastatic soft tissue sarcomas

The therapeutic results of pulmonary resection for metastatic soft tissue sarcomas were analyzed. From 1970 to 1992, 23 patients (15 male and 8 female) underwent 40 pulmonary resections for metastatic soft tissue sarcomas. Nine (39%) patients had multiple thoracotomies for recurrences (range, 2-6). The 5-year actuarial overall survival was 32% (median, 28 months). Statistical analysis showed that age, gender, location of primary tumor, histology, site of pulmonary metastasis, tumor doubling time, or chemotherapy did not impact on survival. Significant prognostic factors associated with improved survival (p < 0.05) included a disease-free interval, and completeness and extent of the initial pulmonary resection. Patients with disease-free intervals > or = 12 months survived longer (5-year survival, 48.5%) than patients with disease-free intervals < 12 months (12%). Patients who could be rendered free of disease at their initial thoracotomy, without extended chest-wall resection, achieved a better outcome (5-year survival, 44%) than the others (5-year survival, 0%).

Noninvasive assessment of left ventricular relaxation using continuous-wave Doppler aortic regurgitant velocity curve. Its comparative value to the mitral regurgitation method

BACKGROUND

The most established parameters of left ventricular (LV) relaxation are peak negative value of the first derivative of LV pressure (-dP/dtmax) and the time constant of isovolumic LV pressure fall. The instantaneous pressure gradient between the aorta and the LV during diastole can be calculated from the continuous-wave Doppler aortic regurgitant velocity spectrum. Because the fluctuation of aortic pressure during LV isovolumic relaxation is negligibly minor and because LV minimal pressure is negligibly low, LV pressure during the isovolumic relaxation period may be derived from the continuous-wave Doppler aortic regurgitant velocity spectrum. This study was designed to clarify whether analysis of continuous-wave Doppler aortic regurgitation recording provides accurate measures of LV relaxation over a wide range of LV function and to determine comparative values of aortic and mitral regurgitation methods in the assessment of LV relaxation.

METHODS AND RESULTS

In eight mongrel dogs with acute ischemic LV dysfunction, the continuous-wave Doppler aortic regurgitant velocity spectrum was recorded simultaneously with high-fidelity LV and aortic pressures, while the continuous-wave Doppler mitral regurgitant velocity spectrum was recorded simultaneously with high-fidelity left atrial and LV pressures. The aortic regurgitant velocity spectrum was provided for the determination of Doppler-derived mean rate of LV pressure fall in 20 ms after the onset of aortic regurgitation (delta P/delta t-AR) and the time interval from the onset of aortic regurgitation to the point at (1-1/e)1/2 of the maximal aortic regurgitant velocity as an estimate of the time constant. The mitral regurgitant velocity spectrum was provided for Doppler-derived mean rate of LV pressure fall in 20 ms after the point of -dP/dtmax (delta P/delta t-MR) and the time interval from the point of -dP/dtmax to the point with mitral regurgitant velocity of (1/e)1/2 of the mitral regurgitant velocity at the point of -dP/dtmax as an estimate of the time constant. delta P/delta t-AR and delta P/delta t-MR correlated well with catheter-derived -dP/dtmax (r = .92, r = .98, P < .01, respectively). The time constant derived from aortic and mitral regurgitant velocity spectra (tau-AR and tau-MR) also correlated well with catheter-derived time constant (r = .84, r = .76, P < .01, respectively). However, a mean difference of the catheter-derived time constant minus tau-MR was larger than tau-AR (29 +/- 30 versus 4 +/- 17 ms, P < .01, presented as mean +/- 2 SD).

CONCLUSIONS

LV relaxation can be assessed from the continuous-wave Doppler aortic regurgitant velocity spectrum. The aortic regurgitation method provides an even more accurate estimate of the time constant compared with the mitral regurgitation method, particularly in the presence of LV dysfunction.