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Biomedical subjects

H Katsume

Publications and source records attributed to H Katsume.

At least 55 records · Page 3Linked to original sources
PubMed1989

The contribution of an extrasystole to postextrasystolic potentiation in papillary muscles of guinea pigs.

It is well known that a short rest period during the regular stimulation of isolated cardiac muscle induces a transient increase of subsequent twitch tension, although the mechanism of postextrasystolic potentiation (PESP) is still unclear. This paper is concerned with the contribution of an extrasystole to the PESP using isolated papillary muscle of guinea pigs. We have found that the length of the coupling interval of the extra-stimulation prior to the rest interval affected the degree of PESP in a coupling interval-dependent way at the same rest period, and the PESP of the same coupling ratio increased and decreased at the rest period was prolonged. Theophylline increased the strength of steady-state twitch tensions, whereas the dependency of PESP on a coupling ratio of extra-stimulation was removed and the PESP decreased with prolonged rest periods. The evidence suggests that the coupling ratio of extra-stimulation might vary the relative contributions of trans-sarcolemmal Ca influx and Ca release from the sarcoplasmic reticulum.

Animals↗
PubMed1989

[An examination of left ventricular peak filling rate and ventricular relaxation rate by simultaneous acquisition of radionuclide ventriculography and left ventricular pressure].

We investigated whether peak filling rate (PFR) obtained from ECG gated radionuclide ventriculography (RNV) reflects left ventricular (LV) relaxation rate or not. Five patients with angina pectoris, 5 patients with old myocardial infarction and 6 controls were studied by simultaneous acquisition of RNV and LV pressure. RNV was performed in modified left anterior oblique position before and during angiotensin II (A II) infusion to elevate their blood pressure about 25 mmHg (A-1) and 50 mmHg (A-2). The data were acquired in a list mode and LV volume curves were reconstructed by forward and backward gating from the R wave of ECG. Actual PFR and corrected PFR by stroke volume (/SV), by end diastolic volume (/EDV), by instantaneous volume (/IV) were calculated from LV volume curve and its first differential curve. LV pressure was simultaneously measured by the catheter-tip micromanometer, and the time constant (T) of assumed exponential decline in LV pressure was calculated as index of LV relaxation rate. Although there was no correlation between actual PFR and T, corrected PFR (/EDV) and PFR (/IV) correlated with T. PFR (/EDV) decreased and T increased during A-1 and A-2. Decrease of PFR (/EDV) corresponded with increase of T. Thus, corrected PFR (/EDV) obtained from RNV reflects the rate of LV relaxation, and was considered to be an useful index to evaluate LV diastolic function.

Adult↗
PubMed1989

[Evaluation of transient dilation of the left ventricle on exercise thallium-201 scintigraphy].

We have noted that some patients with ischemic heart disease have a pattern of transient dilation of the left ventricle on the immediate post exercise images as compared with 3 hour redistribution images. We assessed correlation between transient dilation of the left ventricle and coronary arteriographic findings in 32 patients with ischemic heart disease and 15 controls. Initial and delayed conventional short axis tomographic images were obtained after reconstruction of 20 projections acquired over 180 degrees. Thirty six radii by every 10 degrees were generated from the center of the middle myocardial images of the short axis. An area surrounded by thirty six points of maximal count on each radius was calculated in initial and delayed images. Transient Dilation Index (TDI) as an index of dilation was determined by dividing an area in initial image by an area in delayed image. There was no difference in TDI between patients with 1 vessel disease and controls, but TDI in patients with two vessel disease and patients with three vessel disease was larger than that in controls. Thus, transient dilation of the left ventricle on exercise Tl scintigraphy was likely to be related to number of stenotic vessel. We concluded that TDI as a simple quantitative index of transient dilation of the left ventricle was useful for detecting multi vessel stenosis.

Cardiomyopathy, Dilated↗
PubMed1989

Cinevideodensitometric quantification of relative coronary arterial stenosis: application to evaluating candidates for percutaneous transluminal coronary angioplasty.

As an alternative to visual interpretations of subjects' angiograms, coronary arteries dilated by percutaneous transluminal coronary angioplasty (PTCA) were evaluated using cinevideodensitometry, and the results were compared with those obtained by the edge detection method. Coronary arteriograms were obtained in various projections and suitable frames were selected for analysis. The frames were transformed to digitized images (512 X 512 X 8 bits) with an image analyzer (MIPRON 1), and cinevideodensitometric and edge detection analyses were performed. Phantom models of various shapes were opacified with contrast medium and were used to test our system. The cineangiograms of 58 patients with ischemic heart disease, 28 of whom had underwent PTCA, were analyzed. A highly linear correlation was observed between the cross-sectional areas of the phantoms and the summed gray levels measured using cinevideodensitometry. Percent area stenosis evaluated by the two methods was accurate and reproducible in measuring the symmetrical stenosis models. However, for the model of asymmetrical stenosis, the measurement by the edge detection method differed according to various projections. Similar results were obtained measuring asymmetrical stenosis in the right coronary artery in vivo in various projections. Based on these experimental results, coronary stenoses dilated by PTCA were evaluated. Prior to PTCA, coronary arterial stenosis measured using the two methods closely approximated each other. However, following PTCA, there were discrepancies between the measurements by the two methods in six cases. This can be accounted for by asymmetrical changes in a luminal cross-section, which cannot be accurately assessed using the edge detection method in single plane projection. In conclusion, cinevideodensitometric measurements of relative coronary arterial stenosis were objective, accurate, and reproducible. According to cinevideodensitometric analysis, eccentric lesions can be measured using a single projection, and tracing arterial borders is unnecessary. It is a useful means in measuring quantitatively the degree of dilatation of coronary arterial stenosis accomplished by PTCA.

Angiography↗
PubMed1989

[Intraventricular flow dynamics in hypertrophic cardiomyopathy with midventricular obstruction investigated by Doppler echocardiography].

Seven patients with hypertrophic cardiomyopathy having midventricular obstruction (MVO) were examined using two-dimensional, conventional Doppler and color Doppler echocardiography to investigate intraventricular flow conditions. The controls were 35 patients with hypertrophic cardiomyopathy without MVO. All MVO patients had "hour-glass" LV cavities during systole, resulting from either hypertrophy at the midventricular level or hypertrophied papillary muscles, where systolic mosaic signals originated. Systolic peak flow velocities at the midventricle ranged from 2.5 to 4.2 m/s, proving the presence of a pressure gradient between the apex and the base of the LV. In fact, a pressure drop of 15-30 mmHg was demonstrated in four patients who underwent cardiac catheterization. These high velocity jet flows were not detectable at the midventricle in the control subjects. Peak ejection velocities in the outflow tracts were significantly lower in patients with MVO compared to those with hypertrophic cardiomyopathy and subaortic stenosis (129 +/- 29 vs 384 +/- 111 cm/s; p less than 0.001). As midventricular obliteration became severe, systolic jets at the midventricle increased in velocity. Waveforms changed from single- to double-peaked, and lasted until the isovolumic relaxation or the rapid filling phase beyond the second heart sound. Consequently, isovolumic relaxation waveforms at the midventricle using the apical approach changed the direction; from "the base to apex" to "the apex to base". An isovolumic signal away from the transducer was only observed in two patients without MVO. Diastolic color reversal and mosaic signals at the midventricle were also seen in five of the seven patients with MVO. Peak flow velocities in the rapid filling phase were significantly higher at the papillary muscle level than at the mitral valve level, indicating that MVO continues up to early diastole. It was suggested that MVO disturbs intraventricular flow dynamics during both systole and diastole. Color Doppler echocardiography is particularly useful in determining the site of obstruction and allows further evaluation by pulsed and continuous wave Doppler techniques to precisely measure pressure gradients. With routine, careful use of Doppler echocardiography, MVO may prove to be a more common entity than was previously believed.

Adult↗
PubMed1989

[Ultrasonic tissue characterization by spectral analysis of myocardial textural pattern].

Based on the fact that ultrasonic myocardial textural patterns are more irregular in the pathological myocardium than in the normal, evaluation of the myocardial tissue character was attempted in vivo using spectral analysis. Parasternal left ventricular long-axis echocardiograms were obtained from five patients with old myocardial infarction diagnosed by history, electrocardiography and coronary angiography. These echocardiograms were transferred to an image analyzer and digitized (256 x 256 x 8). The waveforms of the gray-scale-changes from the normal myocardium showed periodicity in each 8-pixel cycle, but those from the infarcted myocardium did not. To quantify pattern changes in gray-scale values in the ultrasound beam direction, spectral analysis was performed by the maximum entropy method (MEM). There were four peaks in the MEM spectra both in the normal and infarcted myocardia, but there was a great significance in these patterns: with high, steep peaks in normal MEM spectra, and low, blunt peaks in infarcted ones. By discriminatory analysis of these four peak values, normalized by the whole spatial frequencies as multivariate, the misclassification rate was 4.8-22.7% in anteroseptal infarctions and 5.0-20.0% in posterior infarctions. Thus, spectral analysis of the myocardial textural pattern has advantages for analyzing routine echocardiograms without corrections by any absolute ultrasonic references. Furthermore, the misclassification rate is so low that we are able to characterize myocardial tissue.

Echocardiography↗
PubMed1989

[Effect of mexiletine on human atrial vulnerability].

The effect of mexiletine on human atrial vulnerability was investigated in 14 subjects (8 with paroxysmal atrial fibrillation, 2 with paroxysmal atrial tachycardia, 2 with ventricular tachycardia, 1 with sick sinus syndrome and 1 with Wolff-Parkinson-White syndrome). During the electrophysiologic study, after 8 consecutive stimuli (A1) were delivered through the electrode catheter positioned at high right atrium, premature stimulus (A2) was introduced, and following measurements were made; 1) Aw: atrial activity width of A1, 2) maximum atrial fragmentation (MAF): the longest atrial activity width of A2, which was expressed by the relative value against Aw, 3) fragmented atrial activity zone (FAZ): the zone of the coupling interval (A1A2) with the prolongation of the atrial activity width at A2 more than 150% against Aw, 4) conduction delay zone (CDZ): the zone of A1A2 with the prolongation more than 20 msec of the intraatrial conduction time at A2 from high right atrium to coronary sinus or low right atrium against the intraatrial conduction time at A1, and 5) right atrial effective refractory period (RAERP). These measurements were repeated after the intravenous administration of mexiletine (2 mg/kg/10 min). 3 cases (case 12, 13 and 14), whose FAZ and CDZ were 0 msec, were excluded from the following evaluation. Mexiletine showed little effect on Aw and RAERP, but significantly shortened MAF and FAZ (p less than 0.001 and p less than 0.05, respectively). CDZ were also reduced in 3 cases and remained unchanged in 6 cases, though no statistical difference of CDZ was recognized between before and after the administration of mexiletine.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

[Left ventricular pressure-volume diagram determined by forward and backward formatting of radionuclide ventriculography and analog pressure data].

Pressure-volume (PV) loop is of great value for the assessment of left ventricular (LV) function, but its clinical application has been limited by methodological complexity. A new system was developed to make accurate loop with simplified procedure, and was applied to clinical and interventional study. The system constitutes of a mobile gamma camera, a poly-amplifier and a data processor (GMS-550U, Toshiba Medical) installed in cardiac catheterization labo for simultaneous raw data handling and successive analysis. Since LV time activity curve (TAC) obtained by usual ECG gating is not fully reliable for a entire cardiac cycle, radionuclide data acquired in list mode was formatted forward and backward from ECG trigger together with analog data of LV pressure, ECG and PCG. PV loops were drawn in 10 patients (OMI, AP, MR, HCM) and 5 normals before and after infusion of angiotensin-II (AII), and Emax and LV work (systolic; SW, diastolic; DW, net; NW = SW - DW) were measured. Radionuclide ventriculography was safely performed with cardiac catheterization even in patients with congestive heart failure. Satisfactory PV loops were obtained by the advantage of simultaneous acquisition of RNV and analog data. Changes of ECG, PCG, volume, pressure and derived indices through one cardiac cycle were readily comparable each other. Peak LV pressure (mmHg) increased from 134 to 159 and then 182 by infusion of AII, but no change in heart rate was observed Emax was higher in normals and AP (mean 1.96 mmHg/ml/m2) than in OMI and MR (range of 0.85-1.36). SW increased in response to rise of LV pressure in all subjects. NW increased in normals and AP, but decreased in OMI and MR with relative increase in DW. In conclusion, this new system is feasible for repetitive studies under drug intervention, since it makes accurate PV loop under physiologic state, i.e. without pacing and volume overloading. Variable changes of SW, DW, and NW in response to afterloading were clarified, which may be useful for the evaluation of cardiac reserve in normal and diseased heart.

Angiotensin II↗
PubMed1988

Swallowing-induced arrhythmia.

Deglutition tachyarrhythmia, first reported in 1926 by Sakai and Mori, is a rare clinical entity. Vagal reflex has been supposed to be responsible for the induction of the arrhythmia. We have recently studied a patient with swallowing-induced premature atrial contractions. Atropine sulfate and catecholamine infusion increased the frequency of the arrhythmia, while beta blockade suppressed it. It is suggested that the mechanism of the swallowing-induced arrhythmia might be related to a sympathetic reflex. As far as we know, there have been few reports in which the sympathetic reflex was proposed to be responsible for the arrhythmia.

Adult↗
PubMed1988

A case of left ventricular aneurysm of uncertain etiology presenting as ventricular tachycardia.

A case of a 59-year-old Asian male with several episodes of syncope and palpitation is reported. Electrophysiologic study disclosed that sustained ventricular tachycardia was induced by programmed electrical stimulation at the right ventricular apex. The electrogram in the left ventricular aneurysm showed delayed activities and the fastest depolarization. Entrainment was observed by faster pacing. Left ventriculography showed a large aneurysm and normal coronary arteries. Congenital left ventricular aneurysm is the most likely clinical diagnosis given the lack of past history of chest pain, myocarditis, cardiomyopathy, etc. Congenital aneurysm which presents as ventricular tachycardia is very rare, and has never been reported in an Asian. Medical management has thus far been successful.

Bundle-Branch Block↗
PubMed1988

Spontaneously occurring hypertrophic cardiomyopathy in the rat. II. Distribution of, and correlations between, various cardiac abnormalities in the WKY/NCrj and its related strains.

We performed gross-anatomic and histologic examinations quantitatively on 18 male and 30 female WKY/NCrj rats, and their 299 first generation off spring. The results were analyzed in comparison with those obtained from 3 other strains of rats. The offspring of the WKY rats showed various cardiac abnormalities quite similar to those in their parents. The cardiac abnormalities in the offspring of the WKY rats were: increased heart weight (in about 10%), left or right atrial hypertrophy (50%), disproportionate septal thickening (50%), small left ventricular cavity (40%), right ventricular hypertrophy (40%), abnormal fiber arrangement greater than 5% in either of the 3 ventricular walls (90%), myocardial fibrosis (70%), and abnormal location of arteries in the ventricular septum (30%). ECG findings of the WHY-F rats such as high QRS complexes and high T waves and axis deviation showed a high sensitivity and specificity in the diagnosis of marked cardiac hypertrophy. Another conspicuous histologic finding observed in the WKY hearts was that the continuity of the latitudinal fiber bundle of the ventricular septum with that of the left ventricular free wall, an important functioning unit for pressure generation in the left ventricle, was markedly disturbed in the area of junction between the 2 walls; the smaller the continuity, the greater the cardiac hypertrophy; the disadvantage of the discontinuity for the pressure generation may be related to the development of cardiac hypertrophy. Also examined were two strains of Wistar rats with the same origin as the WKY/NCrj. These rats also had gross-anatomic and histologic abnormalities of the heart quite similar to those in the 2 generations of WKY/NCrj rats, suggesting that a common factor related to the development of the abnormalities, probably a genetic predisposition, has been transmitted in these 3 strains.

Animals↗
PubMed1988

[Transmitral blood flow velocity patterns evaluated by pulsed Doppler echocardiography in diagnosing transient myocardial ischemia].

To evaluate the influences of transient myocardial ischemia on transmitral blood flow velocity patterns, pulsed Doppler echocardiography was performed during coronary artery occlusion in 10 anesthetized open-chest dogs, and also during esophageal pacing or the administration of dipyridamole in 79 patients with coronary artery disease (CAD), and in 19 control subjects. During occlusion of the coronary artery, an abrupt decrease in the peak velocity of the rapid filling wave (R) was noted within one min simultaneously with rapid decrease of % wall thickening in the ischemic regions. The peak velocity of atrial filling was augmented compensatorily. Although the transmitral blood flow velocity pattern did not change in the controls with esophageal pacing, changes similar to those which were obtained during experimental studies were demonstrated in CAD patients. There were no significant differences between transmitral blood flow velocity patterns of patients with multivessel disease and those with single vessel disease. Ischemic changes in transmitral blood flow velocity patterns were not demonstrated in patients with mitral regurgitation. Sublingual nitroglycerin normalized post-pacing abnormal blood flow velocity patterns. In contrast, after the intravenous administration of 0.56 mg/kg of dipyridamole, R and A were increased and the A/R ratio was unchanged both in CAD patients and the control groups. Deceleration time, or the half time, was prolonged during both provocation tests in CAD patients, and these changes were transient and were restored within several min. Furthermore, they were noted more frequently than was the development of ST depression on ECG, or chest pain. These findings indicate that the transmitral blood flow velocity patterns obtained by pulsed Doppler echocardiography are useful for detecting transient myocardial ischemia, though they have limitations in diagnosing the extent of coronary artery disease.

Animals↗
PubMed1987

Devices external pulse generator: a reliable temporary pacemaker?

Two cases of malfunctioning APC (American Pacemaker Company) Devices pacemakers are reported. Two patients with sick sinus syndrome were temporarily paced using APC Devices pacemaker models EC 4542 and EV 4543 respectively, which showed transient increase (53% and 83% of the preset rate, respectively) in pacing rate. The sudden increase of the pacing rate might be the pacemaker's design to switch to fixed-rate pacing at nominally 25% higher than the selected rate in the presence of an excessive level of electrical interference. However, the increased rate was much faster than the interference rate. Great caution should be paid when APC Devices pacemaker is to be used.

Female↗
PubMed1987

[Transmitral flow patterns during acute coronary artery occlusion: experimental and clinical evaluations by pulsed Doppler echocardiography].

To evaluate left ventricular diastolic properties during acute myocardial ischemia, transmitral flow patterns were analyzed by two-dimensional pulsed Doppler echocardiography. In a preliminary study of transient coronary artery occlusion in anesthetized open-chest dogs, the following results were obtained: decreased peak velocity of rapid filling, prolonged rapid filling period, and compensatory increase in the peak velocity of atrial filling. These changes occurred nearly concomitantly with decreased cardiac output, elevated left atrial and left ventricular end-diastolic pressures, and decreased left ventricular systolic pressures. With reperfusion of the coronary artery, these parameters rapidly returned to the base line values. In acute and transient myocardial ischemia induced by intracoronary balloon inflation during therapeutic percutaneous transluminal coronary angioplasty (PTCA) in man, similar changes in these parameters were observed, and the changes were more marked in PTCA for the left anterior descending artery as compared with that of the right coronary artery. In conclusion, noninvasive two-dimensional pulsed Doppler echocardiography is of practical use in evaluating deterioration of the diastolic function of the left ventricle during acute and transient myocardial ischemia.

Angioplasty, Balloon↗
PubMed1987

[Clinical utility of spatial color mapping vectorcardiography in diagnosing myocardial infarction: comparison with 201Tl scintigraphy].

The feasibility of spatial color mapping vectorcardiography in diagnosing the site and extent of the old myocardial infarct was evaluated in comparison with 201T1 scintigraphy. Vectorcardiographic data made by Frank's technique were entered in the personal computer and the QRS complexes were plotted over 112 points crossing the latitude of each 20 (from 20N to 80S) degrees and longitude of each 20 degrees from 20W to 20E on the spherical body. Eight colors were assigned according to the direction of the QRS vector. To construct a territorial map, the apical, then, the septal, anterior, lateral, inferior and posterior portions were determined from the normal 201Tl scintigrams. Myocardial images obtained in the anterior, left anterior oblique and lateral projections were analyzed by the circumferential profile curve. Diagnostic specificity for infarction was greater than 60%, and especially high (90%) in the anterior, apical and lateral regions, but relatively low (50%) in the septal, inferior and posterior regions. Accuracies exceeded 64%. The infarcted areas assessed by spatial color vectorcardiography agreed with those assessed by 201T1 myocardial scintigraphy. Thus, spatial color vectorcardiography was simple and useful for diagnosing the site and extent of myocardial infarction.

Adult↗