Biomedical subjects
S Nakatani
Publications and source records attributed to S Nakatani.
Mechanism of improvement in exercise capacity after the maze procedure combined with mitral valve surgery.
OBJECTIVE: To clarify the mechanism of improvement in exercise capacity after the maze procedure. DESIGN: Retrospective study. SETTING: Tertiary referral centre. PATIENTS: 26 patients (mean (SD) age 57 (9) years) with atrial fibrillation (AF) and mitral valve disease were studied with echocardiography and cardiopulmonary exercise testing before and after the maze procedure combined with mitral valve surgery. Of these, eight had persistent AF and 18 had restored sinus rhythm (SR) by the surgery. Six patients (mean (SD) age 59 (12) years) with AF undergoing mitral valve surgery without the maze procedure who had cardiopulmonary exercise testing before and after the surgery formed the control group. MAIN OUTCOME MEASURES: Echocardiographic parameters of atrial function were measured from transmitral flow recordings. Peak oxygen uptake (VO2) and the slope of the relation between VO2 and workload (ratio of DeltaVO2 to Delta work) were determined as indices of exercise capacity. RESULTS: The degree of improvements in peak VO2 and the ratio of DeltaVO2 to Delta work after the mitral valve surgery was comparable between the maze and control group. It was also comparable between patients with and those without successfully restored SR after the maze procedure. The degree of the increase in peak VO2 correlated with the change in left atrial diameter (r = -0.40, p = 0.047) but atrial contraction did not correlate with the increase. CONCLUSIONS: Improvement in exercise capacity may not be caused by restored SR and atrial contraction but may at least partly relate to the reduction of left atrial size and improvement of haemodynamic variables by the surgery.
Fragile left atrial thrombus successfully treated with anticoagulants.
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Rapid and simultaneous HLA class I (-A, -B and -C loci) DNA typing using the microtitre plate-reverse hybridization assay (MRHA).
We have established a precise, rapid, simple and practical HLA class I DNA typing method using the microtitre plate-reverse hybridization assay (MRHA), which enables us to perform simultaneous DNA typing of the HLA-A, -B and -C loci using the same PCR parameters and hybridization conditions. PCR-amplified products for the HLA-A, -B and -C loci were hybridized, respectively, with sequence-specific oligonucleotide (SSO) probes, which were immobilized covalently onto a microtitre plate, in hybridization buffer containing formamide at 37 degrees C. After washing at room temperature, the bound PCR products were detected by peroxidase-conjugate streptavidine followed by colour development such as enzyme immunoassay (EIA). In addition to the simple thermoregulation for hybridization and postwashing, strong positive signals, low background and high reproducibility, this DNA typing method enabled simultaneous typing of the HLA-A, -B and -C loci using a single microtitre plate as in HLA serotyping. The assignment of the HLA genotype was easily achieved by automated colorimetric reading and computer software, based on the cut-off value (threshold) established for each probe. For routine HLA class I typing, it may be possible to replace serological typing with the HLA class I DNA typing system using our MRHA method.
Images in cardiology. Unroofed coronary sinus.
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Effect of tissue Doppler on the accuracy of novice and expert interpreters of dobutamine echocardiography.
The subjective interpretation of dobutamine echocardiography (DBE) makes the accuracy of this technique dependent on the experience of the observer, and also poses problems of concordance between observers. Myocardial tissue Doppler velocity (MDV) may offer a quantitative technique for identification of coronary artery disease, but it is unclear whether this parameter could improve the results of less expert readers and in segments with low interobserver concordance. The aim of this study was to find whether MDV improved the accuracy of wall motion scoring in novice readers, experienced echocardiographers, and experts in stress echocardiography, and to identify the optimal means of integrating these tissue Doppler data in 77 patients who underwent DBE and angiography. New or worsening abnormalities were identified as ischemia and abnormalities seen at rest as scarring. Segmental MDV was measured independently and previously derived cutoffs were applied to categorize segments as normal or abnormal. Five strategies were used to combine MDV and wall motion score, and the results of each reader using each strategy were compared with quantitative coronary angiography. The accuracy of wall motion scoring by novice (68 +/- 3%) and experienced echocardiographers (71 +/- 3%) was less than experts in stress echocardiography (88 +/- 3%, p <0.001). Various strategies for integration with MDV significantly improved the accuracy of wall motion scoring by novices from 75 +/- 2% to 77 +/- 5% (p <0.01). Among the experienced group, accuracy improved from 74 +/- 2% to 77 +/- 5% (p <0.05), but in the experts, no improvement was seen from their baseline accuracy. Integration with MDV also improved discordance related to the basal segments. Thus, use of MDV in all segments or MDV in all segments with wall motion scoring in the apex offers an improvement in sensitivity and accuracy with minimal compromise in specificity.
Prevention of hepatocellular carcinoma in patients with chronic active hepatitis C and cirrhosis.
In a prospective randomised controlled study, 90 patients with chronic active hepatitis C and compensated cirrhosis were assigned symptomatic treatment or interferon alfa (IFN-alpha). We report data on decompensation, detection of hepatocellular carcinoma, and mortality rates. IFN-alpha gave a sustained response in only a small proportion of patients, but worsening of compensated cirrhosis was prevented and development of hepatocellular carcinoma was inhibited, increasing the survival rate. The risk ratio of IFN-alpha versus symptomatic treatment decreased by 0.250 for progression to Child-Pugh grade B, 0.256 for detection of hepatocellular carcinoma, and 0.135 for a fatal outcome.
[Multicentric Castleman's disease with reversible left ventricular diffuse hypokinesis].
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Combined abnormalities of semilunar valves: quadricuspid pulmonary and bicuspid aortic valves.
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Long-term follow-up of atrial contraction after the maze procedure in patients with mitral valve disease.
OBJECTIVES: We sought to determine the effectiveness of the maze procedure for maintaining sinus rhythm and atrial contraction for a long period in patients with mitral valve disease. BACKGROUND: Although the maze procedure for atrial fibrillation (AF) has been effective in restoring sinus rhythm in patients with mitral valve disease, the long-term results of this procedure have not been determined. METHODS: We echocardiographically studied 94 consecutive patients with mitral valve disease before, as well as early (3.1 +/- 3.3 months) and late (2.2 +/- 0.9 years) after, the maze procedure. Peak velocity and the time-velocity integral of the left ventricular (LV) diastolic filling wave during atrial contraction (A wave), as well as the atrial filling fraction (calculated as the ratio of the time-velocity integral of the A wave to total diastolic filling), were obtained from transmitral flow recordings. Peak A wave velocity > or =10 cm/s was considered to indicate echocardiographic evidence of effective atrial contraction. RESULTS: Regular rhythm with P waves was restored in 70 patients (74%) in the early stage and in 59 patients (63%, p = 0.09) in the late stage after the maze procedure. Forty-seven patients (50%) in the early stage and 36 patients (38%, p = 0.14) in the late stage showed effective atrial contraction by Doppler echocardiography. Left atrial (LA) and LV end-diastolic diameters significantly decreased after the procedure (from 59 +/- 13 to 48 +/- 7 mm, p < 0.01; and from 54 +/- 9 to 47 +/- 5 mm, p < 0.01, respectively) and did not show significant changes during the follow-up period. Once atrial contraction was resumed, its degree did not change between the early and late stages after the maze procedure (17 +/- 6% vs. 17 +/- 6% for atrial filling fraction). CONCLUSIONS: Sinus rhythm and atrial contraction recovered early after the maze procedure in most patients and were maintained for more than two years. Once active atrial contraction was resumed, the degree of contraction did not change thereafter. These results demonstrate that the maze procedure is effective for a long period in patients with mitral valve disease.
An enhanced method for left ventricular volume and ejection fraction by triggered harmonic contrast echocardiography.
To elucidate the validity and reproducibility of the use of intravenous echo-contrast agent in the evaluation of left ventricular (LV) performance, we measured LV volume and ejection fraction (EF) in 42 patients with triggered harmonic contrast imaging (THCI), compared with continuous harmonic imaging without contrast agent (CHI) and with cineventriculography (CVG). In 10 of 42 patients, THCI improved LV border delineation which could not be obtained even with CHI. LV end-diastolic, end-systolic volumes and EF by both CHI and THCI correlated well with those by CVG. Although LV volumes are underestimated, THCI lessened the mean differences to about in half, compared with CHI. The observer variabilities obtained using THCI were smaller than those by CHI. These results indicate the validity of LV enhancement and the measurement of EF using THCI. We suggest that this method noninvasively provides more accurate LV systolic function with the acceptable reproducibility.
Mitral inertance in humans: critical factor in Doppler estimation of transvalvular pressure gradients.
The pressure-velocity relationship across the normal mitral valve is approximated by the Bernoulli equation DeltaP = 1/2 rhoDeltav(2) + M. dv/dt, where DeltaP is the atrioventricular pressure difference, rho is blood density, v is transmitral flow velocity, and M is mitral inertance. Although M is indispensable in assessing transvalvular pressure differences from transmitral flow, this term is poorly understood. We measured intraoperative high-fidelity left atrial and ventricular pressures and simultaneous transmitral flow velocities by using transesophageal echocardiography in 100 beats (8 patients). We computed mean mitral inertance (M) by M = integral((DeltaP)-(1/2 x rho v(2))dt/integral(dv/dt)dt and we assessed the effect of the inertial term on the transmitral pressure-flow relation. ranged from 1.03 to 5.96 g/cm(2) (mean = 3.82 +/- 1.22 g/cm(2)). DeltaP calculated from the simplified Bernoulli equation (DeltaP = 1/2. rhov(2)) lagged behind (44 +/- 11 ms) and underestimated the actual peak pressures (2.3 +/- 1.1 mmHg). correlated with left ventricular systolic pressure (r = -0.68, P < 0.0001) and transmitral pressure gradients (r = 0.65, P < 0.0001). Because mitral inertance causes the velocity to lag significantly behind the actual pressure gradient, it needs to be considered when assessing diastolic filling and the pressure difference across normal mitral valves.
Serial assessment of left and right ventricular filling in patients with congestive heart failure.
Serial changes in the diastolic filling of both ventricles were studied using Doppler echocardiography in 19 patients with congestive heart failure from the acute to the convalescent stage. During the acute stage, left ventricular early filling velocity (E) was high (88 +/- 17 cm/s) and atrial filling velocity (A) was low (44 +/- 23 cm/s), whereas the right ventricular E was depressed (17 +/- 8 cm/s) and A was enhanced (40 +/- 9 cm/s). As the condition improved, left ventricular E decreased (43 +/- 11 cm/s, p < 0.01) and A increased (59 +/- 24 cm/s, p < 0.01) along with a decrease in the left ventricular and atrial dimensions. In contrast to the changes in left ventricular filling, right ventricular E increased (31 +/- 10 cm/s, p < 0.01) and A decreased (32 +/- 5 cm/s, p < 0.05). There are opposite directional changes in left and right ventricular filling with clinical improvement from the acute to the convalescent stage of congestive heart failure, which suggest that the changes are related to improvement of the hemodynamic conditions of both ventricles. The changes in the right ventricular filling pattern was likely to be related to changes in right ventricular afterload, ventricular interaction and external constraint rather than a change in right ventricular filling pressure.
Comparative left ventricular functional and neurohumoral effects of chronic treatment with carvedilol versus metoprolol in patients with dilated cardiomyopathy.
The efficacy of treating dilated cardiomyopathy with metoprolol was compared with that of carvedilol. Metoprolol was administered to 29 patients, and carvedilol to 62. Patients who could not be dosed with up to 40 mg daily of metoprolol or 20 mg daily of carvedilol were defined as intolerant. As well as the tolerability of these beta-blockers, the effects on left ventricular end-diastolic dimension (LVDd), fractional shortening (FS), plasma atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) concentrations, the delayed heart and mediastinum (H/M) ratio determined from metaiodobenzylguanidine imaging were compared. Drug intolerance occurred in 24% of patients in the metoprolol group and 19% in the carvedilol group. Among the drug-tolerant patients, LVDd, FS and plasma BNP concentration improved in both groups and to the same degree. Only 25% of drug-tolerant patients in the metoprolol group had a delayed H/M ratio below 1.9 compared with 57% in the carvedilol group. Both metoprolol and carvedilol, when tolerated, improve cardiac function and neurohumoral factors to the same degree. However, carvedilol is preferable to metoprolol for patients with a low delayed H/M ratio.
Biliary tract of the rat as observed by scanning electron microscopy of cast samples.
The three-dimensional distribution of the biliary tract in the rat was studied by scanning electron microscopy of biliary casts. The casts were prepared by a retrograde infusion of a low viscosity or monomeric methacrylate resin mixture into the common bile duct. No resin flow from the bile canaliculi to sinusoidal capillaries was ever noted. Bile canaliculi formed intricate meshworks and drained via the Hering's canals into the bile ductules. The bile canalicular meshworks of adjacent lobules intercommunicated with each other. The bile ductules formed a marked periportal plexus around the portal vein branch, and drained into the intrahepatic bile duct running along the portal vein branch. The junctional zone of the Hering's canal and bile ductule usually showed an ampullary dilation. When the Hering's canal directly drained into a thick bile ductule or into a periportal plexus of bile ductules, such an ampullary dilation at the origin of the bile ductule was never replicated. The extrahepatic bile duct protruded many crypt-like projections which presumably corresponded to parietal glands. It is suggested that the periportal plexus of bile ductules may store the bile as a substitute for the gallbladder.
Intraoperative ultrasound arteriography with the "Coded Harmonic Angio" technique. Report of three cases.
The result of combining the ultrasound Coded Excitation method and an ultrasound contrast agent (UCA), the Coded Harmonic Angio (CHA) technique provides arterial images with exceptional spatial, temporal, and contrast resolution that are comparable to those produced by conventional digital subtraction angiography. The authors report on their experience with intraoperative ultrasound arteriography performed using the transdural CHA technique in three patients: one harboring a meningioma, another with a middle cerebral artery aneurysm, and a third with an arteriovenous malformation. The present study demonstrates how intraoperative cerebral ultrasound arteriography can be applied to assess the adequacy of neurovascular procedures without the presence of an experienced operator.
[Clinical validation of accuracy of anatomical M-mode measurements: effect of harmonic imaging].
OBJECTIVES: Recent advances in ultrasound technology allow reconstruction of images from stored radiofrequency information and creating of M-mode echocardiograms along an M-mode cursor of any direction (anatomical M-mode echocardiography). METHODS: The accuracy of the measurements obtained by anatomical M-mode echocardiography was evaluated by comparing the measurements with those by B-mode echocardiography with or without harmonic imaging in 8 normal subjects and 14 patients with cardiac disorders. Measurements used the left ventricular short-axis image in 4 different directions (0 to 6, 3 to 9, 1 to 7 and 5 to 11 o'clock). RESULTS: Anatomical M-mode and B-mode measurements showed good linear relationships with correlation coefficients of 0.90 to 0.99 in any of the 4 directions. However, measurements in the lateral direction (3 to 9 o'clock) showed larger errors than those in the other directions (p < 0.05). With the use of harmonic imaging, the errors tended to become smaller, although it did not reach statistical significance. CONCLUSIONS: Anatomical M-mode echocardiography accurately measures the left ventricular internal diameter in any direction except the lateral direction. Harmonic imaging is useful to decrease the errors.
[Abnormal regurgitation in the left atrium after mitral valve replacement].
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