Biomedical subjects

T Masuyama

Publications and source records attributed to T Masuyama.

At least 73 records · Page 4Linked to original sources

PubMed1996

Zero flow pressure in human coronary circulation.

UNLABELLED: Coronary pressure flow (P/F) relationship has been investigated mainly from the viewpoint of coronary resistance. However, recent experimental evidence suggests that the zero flow pressure intercept (Pzf) provides important characteristics of coronary circulation. Although Pzf is likely to provide meaningful information about characteristics of coronary circulation, no data are available about Pzf in humans. The authors attempted to determine Pzf in humans by analyzing P/F relationship during long cardiac pause. This relationship, provoked by intracoronary adenosine triphosphate (ATP) infusion, was analyzed in 9 patients (8 men, 1 woman) with coronary heart disease (ages: fifty-six +/- six years). After the diagnostic cardiac catheterization, ATP, 0.6 mg/3 mL, was administrated by bolus intracoronary injection during measurements of coronary blood flow velocity. Coronary blood flow velocity in the left anterior descending artery was measured with a 0.018-inch Doppler angioplasty guide wire (FloWire, Cariometrics, Inc., Mountain View, Calif.). The dynamic P/F relationship was obtained by correlation of the instantaneous aortic pressure and flow velocity with each other at constant intervals. The least square linear regression analysis was applied to the P/F data to yield the extrapolated Pzf axis. Immediately after intracoronary injection of ATP, long pause (5320 +/- 1498 msec) appeared and coronary blood flow velocity decreased to 11 +/- 8 cm/sec. Pzf calculated with P/F relationship was 14 +/- 7 mmHg. CONCLUSIONS: Thus, the results clearly demonstrate that Pzf is higher than right atrial and left ventricular end-diastolic pressure in humans, indicating the complexity of the determinants of the Pzf.

Adenosine Triphosphate↗

PubMed1996

Coronary back flow pressure is elevated in association with increased left ventricular end-diastolic pressure in humans.

To clarify the effect of left ventricular (LV) diastolic pressure on the coronary pressure-flow relation in humans, the instantaneous diastolic coronary pressure-Doppler flow velocity relation was analyzed at rest and during papaverine-induced maximal vasodilation in 15 patients with angiographically normal coronary arteries. The values for slope (alpha PF) and zero-flow pressure intercept (Pzf index) of the instantaneous diastolic coronary pressure-flow velocity relation were obtained by a linear regression analysis. Although alpha PF did not correlate with LV end-diastolic pressure (EDP), the Pzf index correlated positively with LVEDP both at rest and during maximal vasodilation (r = 0.64, P < 0.05 and r = 0.58, P < 0.05, respectively). Thus, the back pressure to coronary inflow, as indicated by the Pzf index, may be elevated in patients with increased LVEDP, resulting in the rightward shift of the maximally dilated coronary pressure-flow relation and decreased maximal coronary flow and reserve at any given perfusion pressure.

Adult↗

PubMed1996

Non-ischemic myocardial fibrosis after long-term asbestos exposure.

To determine whether or not myocardial fibrosis in the left ventricle increases after exposure to asbestos fiber, we studied myocardial fibrosis in 42 autopsied hearts; 17 of asbestosis (AS) and 18 of chronic pulmonary disease (CP) without pneumoconiosis. Seven patients with extracardiopulmonary disease were used as a control group (CONT). The extent of myocardial fibrosis in the left ventricle was significantly greater in the AS group compared to the other groups (AS 3.6 +/- 1.3% vs. CP 2.4 +/- 1.0% vs. CONT 1.6 +/- 0.8%). There was a significant difference in the appearance ratio of focal fibrosis between the asbestosis group and the other groups. Focal fibrosis was observed in none of 7 control patients, in 3 of 18 patients with chronic pulmonary disease and in 9 of 17 patients with asbestosis. We concluded that characteristic myocardial fibrosis was observed in humans after long-term asbestos exposure.

Adult↗

PubMed1995

Temporal changes in myocardial perfusion patterns in patients with reperfused anterior wall myocardial infarction. Their relation to myocardial viability.

BACKGROUND: Several studies demonstrated ischemic microvascular damage in patients with acute myocardial infarction (AMI). In this study, myocardial contrast echocardiography (MCE) was used to assess the temporal changes in myocardial perfusion after reflow and to investigate the relation between MCE findings and myocardial viability. METHODS AND RESULTS: MCE was performed with the intracoronary injection of sonicated microbubbles before and shortly after coronary reflow and 1 month later in 45 patients with anterior wall AMI. MCE before reflow was analyzed to determine the risk area as an area of contrast defect in the apical long-axis view. MCE images after reperfusion were analyzed to determine peak contrast intensity, which should be in proportion to the concentration of microbubbles within the microvasculature and in the infarcted and normal myocardium, and the ratio of these (PI ratio) was used to assess microvascular integrity. Areas of residual contrast defect were expressed as a ratio to those of left ventricular myocardial (RCD ratio) to assess the spatial extent of the MCE "no reflow." Regional wall motion (RWM, SD per chord) in the territory of the left anterior descending coronary artery was determined by the centerline method in both the acute and late stages. Although the PI ratio was extremely low shortly after coronary reflow, it increased in the late stage of AMI with the improvement in regional contractile function (RWM, -3.2 +/- 0.5 versus -2.6 +/- 1.0, P < .01; PI ratio, 0.44 +/- 0.25 versus 0.60 +/- 0.29, P < .01). Reduction in the RCD ratio was observed even in 15 patients with MCE no reflow in the acute stage (0.33 +/- 0.09 versus 0.16 +/- 0.11, P < .01). Then we investigated the relation between residual contractile function and microvascular integrity in the late stage. A significant correlation was found between the PI ratio and RWM (r = .73, P < .001) in the late stage of the AMI. CONCLUSIONS: (1) Recovery from ischemic microvascular damage is generally observed in the late stage of AMI in association with improvement in myocardial contractile function. The degree of improvement in contractile function and microvascular integrity, however, varies among patients. (2) Contrast peak intensity in the late stage of infarction may provide a useful estimate of myocardial viability.

Adult↗

PubMed1995

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.

Adult↗

PubMed1995

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.

Animals↗

PubMed1995

Alterations of bone mineral density of the femurs in hemiplegia.

We evaluated the bone mineral density (BMD) of the bilateral femurs in 112 patients with hemiplegia using dual-energy X-ray absorptiometry in order to elucidate the effect of disuse and immobilization. BMD of the paretic side was significantly reduced compared with that of the non-paretic side in hemiplegic patients (femoral neck 0.582 +/- 0.014 g/cm2 versus 0.623 +/- 0.014 g/cm2 and total femur 0.645 +/- 0.02 g/cm2 versus 0.702 +/- 0.017 g/cm2; mean +/- SEM, P < 0.01, respectively). Femoral BMD in both the paretic and nonparetic limb had significantly (P < 0.01) lower values than in age- and sex-matched controls, but the paretic side had a more significant reduction of BMD; femoral neck -20% versus -14% and total femur -24% versus -18%. In addition, patients with impaired activities of daily living (ADL), evaluated by a mobility score, had significantly decreased BMD ratios of paretic/nonparetic side than patients with improved ADL (femoral neck 91% versus 97%, P < 0.01 and total femur 89% versus 94%, P < 0.05). Our results indicated that BMD of both femurs of patients with hemiplegia was reduced, although the paretic side showed a greater BMD decrease. This decrease might be prevented or reduced by improvement of ADL.

Activities of Daily Living↗

PubMed1995

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.

Adult↗

PubMed1995

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.

Acute Disease↗

PubMed1995

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.

Algorithms↗

PubMed1995

Degree of external force to the left ventricle determines hemodynamic response to nitroprusside in failing hearts: comparison with the response to dobutamine.

Vasodilators frequently, although not always, increase cardiac output (CO) in patients with congestive heart failure (CHF) despite a decrease in left ventricular (LV) diastolic pressure. In patients with CHF, vasodilator-induced decrease in LV diastolic pressure without decrease in "preload" plays an important role in the vasodilator-induced increase in CO failure that may be caused by a vasodilator-induced reduction in external force to the LV. To clarify the hypothesis that a hemodynamic response to vasodilators depends on the degree of external force to the LV in failing hearts before drug administration and to examine whether the degree of the external force also affects a hemodynamic response to positive inotropic agents, we produced in 17 dogs two different conditions of LV dysfunction with high LV end-diastolic pressure (EDP: > or = 15 mm Hg), i.e., 1 with high right ventricular (RV) EDP (condition 1) and the other with lower RVEDP than condition 1 (condition 2), and compared hemodynamic effects of nitroprusside or dobutamine between these two conditions. Condition 1 was produced by the injection of a small dose of microspheres into the left coronary artery and intravenous infusion of dextran. Condition 2 was produced only by the injection of a large dose of microspheres. The nitroprusside-induced decrease in LVEDP was associated with a greater decrease in RVEDP and lesser decreases in mean left atrial pressure and LV end-diastolic diameter in condition 1 than in condition 2. CO increased in condition 1; however, CO then decreased in condition 2. The nitroprusside-induced changes in CO inversely correlated with those in RVEDP (r = 0.65, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗

PubMed1995

Production and expression of granulocyte- and macrophage-colony-stimulating factors in newborns: their roles in leukocytosis at birth.

We analyzed the production and expression of three colony-stimulating factors (CSFs) in neonates to clarify the mechanism of leukocytosis at birth. Serial blood samples (n = 23) were collected from mothers, cord blood, and from newborn infants on days 1, 5, and 30 after birth. The serum levels of granulocyte-CSF (G-CSF), granulocyte/macrophage/CSF (GM-CSF) and macrophage-CSF (M-CSF) were measured by ELISA. The G-CSF levels on day 1 after birth were significantly higher than those thereafter, and they were also higher in the mothers than those on days 5 and 30 after birth. The GM-CSF levels did not change significantly during the neonatal period. The serum M-CSF levels were higher on postnatal day 1 than at other times, and gradually decreased thereafter. To confirm the production sites of G-CSF and M-CSF, the mRNA for these CSFs in peripheral mononuclear cells (MNCs) from healthy adults, mothers, and cord blood were analyzed by PCR. The expression of G-CSF and GM-CSF mRNA was undetectable in MNCs from adults, mothers, and cord blood, while these cells expressed low levels of M-CSF mRNA. After stimulation with lipopolysaccharide or phorbol myristate acetate, the MNCs expressed high levels of G-CSF and GM-CSF mRNA. The levels of G-CSF PCR products in cord MNCs were lower than those in adult and maternal MNCs. The expression of M-CSF mRNA was virtually unchanged by stimulation. To detect the localization of G-CSF and M-CSF in the placenta and umbilical cord, these tissues were immunocytochemically stained with anti-G-CSF and anti-M-CSF antibodies, G-CSF and M-CSF were expressed in trophoblasts and decidual stromal cells, whereas the umbilical cord did not express these CSFs. Moreover, large amounts of G-CSF and M-CSF were detected in the supernatant of cultured trophoblasts and decidual stromal cells. The expression of G-CSF and M-CSF in these cells was confirmed by PCR. These findings suggested that G-CSF and M-CSF produced in the placenta (trophoblasts and decidual stromal cells) are the major factors that induce leukocytosis in newborn infants at birth.

Base Sequence↗

PubMed1995

Contribution of atrial reservoir function to ventricular filling in hypertensive patients. Effects of nifedipine administration.

We designed this study to access the importance of left atrial function as a contributor to mitral flow velocity pattern in hypertensive patients. In hypertensive patients the early diastolic flow velocity and ratio of early to late diastolic flow velocity in the mitral flow velocity pattern increase in association with sublingual administration of nifedipine. These changes have been interpreted as signs of improved left ventricular diastolic function; however, the mitral flow velocity pattern is also affected by various other factors. Thus, the nifedipine-induced changes may not necessarily indicate the improvement of left ventricular diastolic function. Transthoracic Doppler echocardiographic parameters of mitral and pulmonary venous flow velocity patterns and left ventricular M-mode echograms were obtained in 16 untreated hypertensive patients before and after sublingual administration of nifedipine (10 mg). Normal values of the parameters were determined in 50 age-matched healthy subjects. After nifedipine peak early diastolic mitral flow velocity increased beyond the normal value, although the peak increasing rate of left ventricular inner dimension, another index of left ventricular diastolic function, did not recover to the normal value. Peak systolic velocity in the pulmonary venous flow velocity pattern increased beyond the normal value, indicating improvement of the reservoir function to the left atrium during systole. Nifedipine-induced normalization of the mitral flow velocity pattern was associated with further abnormalities of the pulmonary venous flow velocity pattern, indicating enhanced left atrial reservoir function.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Basal release of endothelium-derived nitric oxide plays an important role in the prevention of afterload mismatch in acute left ventricular dysfunction.

The basal release of endothelium-derived nitric oxide (EDNO) is considered to play an important role in regulating the vascular tone in normal subjects; however, its role in the presence of acute heart failure is unknown. This study was designed to clarify the role of a basal release of EDNO in the presence of acute heart failure. Acute ischemic left ventricular (LV) dysfunction was produced in 22 dogs by coronary microembolization. After the embolization, only saline solution was intravenously infused for sixty minutes in 10 dogs. In another 12 dogs, NG-monomethyl-L-arginine (L-NMMA), which is known to inhibit the formation of EDNO in the vascular endothelium, was intravenously infused at a rate of 20 micrograms/kg/minute for sixty minutes. Infusion of saline solution did not produce any changes in hemodynamic variables. Infusion of L-NMMA caused increases in mean aortic pressure, systemic vascular resistance, and LV end-diastolic pressure without changes in the LV peak + and - dP/dt (time constant) of LV pressure fall, and these changes were associated with a giant "v" wave in the tracing of left atrial pressure and a decrease in cardiac output. The basal release of EDNO may play an important role in the prevention of afterload elevation, subsequent cardiac output reduction, and afterload mismatch in the presence of acute heart failure.

Acute Disease↗

PubMed1995

Alterations in the mitral flow velocity pattern induced by acute myocardial infarction. Doppler findings before and after infarction.

Several studies have demonstrated that myocardial infarction (MI) is likely to alter left ventricular diastolic function. However, it is unclear whether MI per se alters Doppler transmitral flow velocity patterns (TMF) clinically. To investigate how myocardial infarction alters TMF clinically, we assessed serial changes in TMF in 13 patients whose TMF patterns were recorded at a mean of 7 months before and after MI in relation to the size of MI. From TMF, early and atrial filling flow velocities (E and A (m/s), respectively), and the E/A ratio, were measured. From simultaneously recorded two-dimensional echocardiograms, left ventricular dimensions and wall motion score (WMS: sum of 17 segmental scores (dys/akinesis = 3 to normal = 0)) were determined. The patients were divided into two subsets based on the values for WMS in the convalescent stage; 8 patients had small MI (WMS < or = 10) and 5 patients had large MI (WMS > 10). In patients with small MI, although E and the E/A ratio decreased at day-1 compared with pre-MI values (pre-MI vs day-1, E; 0.54 +/- 0.12 vs 0.39 +/- 0.15, p < 0.05, E/A ratio 0.91 +/- 0.23 vs 0.68 +/- 0.14, p < 0.05), these values increased to levels similar to those observed at pre-MI in the convalescent stage. There were no changes in left ventricular dimensions between pre-MI and in the convalescent period. In patients with large MI, the changes in the TMF patterns varied among patients after MI. In 3 patients with WMS < or = 25, E and E/A ratio were decreased in the convalescent stage, compared with pre-MI values. In 2 patients with WMS > 25, TMF patterns showed 'pseudonormalization' (E/A ratio > 1.0) throughout the follow-up period, with a progressive increase in left ventricular dimension. Thus, MI per se does not always produce clear changes in the Doppler TMF pattern in clinical settings, and the size of the MI seems to be a determinant of the TMF pattern after MI.

Adult↗

PubMed1995

[Comparison of blood pressures measured directly at the radial and dorsalis pedis arteries during epidural anesthesia].

Differences of blood pressures measured directly at the radial and dorsalis pedis arteries were compared in relation to the sites of the epidural puncture. Epidural catheters were inserted at C7-Th9 in the upper (U) group (n = 7), and at L1-4 in lower (L) group (n = 7). In the awake, unanesthetized state, the systolic, mean and diastolic radial-to-dorsal pressure differences (DR-D) were -21.9 +/- 11.0 mmHg (mean +/- SD), 0.9 +/- 1.1 mmHg and 2.1 +/- 2.1 mmHg respectively. Following epidural infusion of mepivacaine, the DR-D values shifted to the negative direction in the U group, and to the positive direction in the L group. Epidural anesthesia had little effect on the DR-D changes during general anesthesia; however, it affected significantly the mean pressure DR-D as well as the systolic pressure DR-D during the periods of preinduction and postemergence. The maximum change in systolic pressure DR-D values was from -19.4 to -36.3 mmHg in a patient of the U group and from -15.6 to 45.4 mmHg in a patient of the L group. The maximum change in mean pressure DR-D values was from 0.0 to -7.4 mmHg in the U group and from 2.1 to 18.3 mmHg in the L group. The DR-D values had significant negative correlations with the deep temperature (palm to sole) differences; the correlation coefficients were: systolic, r = -0.50; mean, r = -0.50; and diastolic, r = -0.41. These results demonstrated that epidural anesthesia changed the physiological central-to-peripheral pressure gradients, probably by influencing the regional peripheral vascular resistance.

Adult↗

PubMed1994

Incidence and time course of left ventricular dilation in the early convalescent stage of reperfused anterior wall acute myocardial infarction.

The incidence and early process of left ventricular (LV) dilation in 52 patients with reperfused anterior wall acute myocardial infarction (AMI) were assessed. All patients achieved coronary reflow within 24 hours of the onset and had a patent infarct-related artery in the convalescent stage. Left ventriculography was performed at pre-reflow and 25 days (mean) later to determine LV end-diastolic volume (ml) with the area/length method. Short-axis echo images at the midpapillary muscle level were recorded at days 1, 7, 14, and 28 of the AMI. With use of the papillary muscles as the internal landmarkers, the LV wall was divided into the anterior and posterior segments, and length and thickness of each segment were determined. Among 52 patients, 10 (19%) had a > or = 20% increase in end-diastolic volume in the convalescent stage. Echocardiographic studies demonstrated that there were no significant changes in lengths and thicknesses of the anterior and posterior segments during follow-up study relative to his or her baseline value in 42 patients without LV dilation. In the patients with LV dilation, however, the anterior segment exhibited a mean increase of 25% in its length with a mean decrease of 21% in its thickness at day 7 relative to their baseline values, but no progressive expansion was observed after day 7. A mean increase of 7% in the posterior segment length without reduction in its thickness first became evident at day 28.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Angiography↗

PubMed1994

Myocardial salvage: its assessment and prediction by the analysis of serial myocardial contrast echocardiograms in patients with acute myocardial infarction.

It has been difficult to assess myocardial salvage in patients with coronary reflow because of the lack of appropriate methods of determining the risk area and assessing effects of coronary reflow in patients, myocardial contrast echocardiography was performed in 28 patients with acute myocardial infarction before reperfusion, immediately after reperfusion, and in the chronic stage with the right and left coronary arterial injection of sonicated ioxaglate. Contrast-deficit and contrast-filled areas before reperfusion were defined as the risk area and noninfarct area, respectively. If the ratio of peak subtracted gray level in the risk area to that in the noninfarct area was < 0.4, the risk area was taken as a contrast defect. Contrast defect was observed even after reperfusion in 8 (29%) patients, and the defect was consistently observed in the chronic stage in all of them. Contrast defect disappeared after reperfusion in the other 20 patients but reappeared in 4 (20%) of them in the chronic stage despite the patent infarct-related vessel. Left ventricular function recovery of the risk area in the chronic stage as assessed with regional wall motion and wall thickness was better in the patients without contrast defect after reperfusion than in patients with persistent or reappeared contrast defect. In conclusion, (1) myocardial salvage is improbable in patients with contrast defect immediately after reperfusion, (2) contrast enhancement immediately after reperfusion does not necessarily imply myocardial salvage in the chronic stage, and (3) myocardial echocardiography in the chronic stage may provide clinically useful information about myocardial salvage in patients with myocardial infarction.

Adult↗