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Biomedical subjects

H Katsume

Publications and source records attributed to H Katsume.

At least 19 recordsLinked to original sources
PubMed1992

Diastolic paradoxic jet flow in patients with hypertrophic cardiomyopathy: evidence of concealed apical asynergy with cavity obliteration.

In 20 of 198 patients with hypertrophic cardiomyopathy, Doppler color flow imaging revealed diastolic paradoxic jet flow across the obliterated left ventricular apex toward the base that suggested the presence of a discrete apical chamber. This prospective study characterized echocardiographic, ventriculographic and scintigraphic findings in these patients, as well as their clinical features. Although echocardiography did not directly show the apical chamber in 13 of the 20 patients, left ventriculography always revealed a small apical outpouching separated from the major basal cavity. Systolic bulging of the apex was always followed by early diastolic shrinkage together with persistent cavity narrowing between the two chambers. After the systolic jet flow, the paradoxic jet flow lasted for 366 +/- 160 ms after aortic valve closure and always extended into the diastolic filling period. The maximal velocity of the paradoxic jet flow occurred during isovolumetric relaxation and the mean velocity was 2 +/- 0.8 m/s, indicating a higher diastolic pressure in the apical chamber than in the main ventricle. Compared with patients who manifested cavity obliteration alone, patients with a paradoxic jet flow more often developed systemic embolism (p less than 0.01), ventricular tachycardia (p less than 0.05) and thallium perfusion abnormalities localized to the apical region (p less than 0.01). Thus, paradoxic jet flow could be an important marker of concealed apical asynergy and the risk of adverse clinical events. The higher diastolic apical pressure suggested by the flow may contribute to the development of an apical aneurysm, even in the absence of fixed coronary artery disease.

Adult↗
PubMed1992

Echocardiographic determination of stroke volume during rapid atrial pacing and volume loading in normal rats.

OBJECTIVE: The aim was to validate echocardiographic assessment of acute changes of left ventricular stroke volume in normal rats. METHODS: By transthoracic use of a 7.5 MHz ultrasonic transducer, the left ventricular dimensions were determined before and during rapid atrial pacing and saline infusion in seven Wistar rats weighing 310-470 g. Left ventricular volume was calculated from short axis dimensions according to a cube function formula. Echo stroke volume (SVE) was then compared with that obtained simultaneously using a pulsed Doppler flow meter placed around the ascending aorta (SVF). RESULTS: The SVE (ml) was decreased from 0.30(SD 0.12) to 0.13(0.06) by rapid pacing and increased from 0.27(0.12) to 0.63(0.16) by volume loading. Regression analysis showed high correlations between SVE and SVF during both pacing (r = 0.84) and infusion (r = 0.91) studies. Furthermore, correlations between SVE and SVF in individual animals were very close (r = 0.87-0.99 in the pacing study and 0.92-0.99 in the volume study). Interobserver and intraobserver variances were small, with close correlations (r = 0.96-0.99) and modest standard errors of the estimate (0.02-0.04 ml) between the two measurements. CONCLUSIONS: Echocardiography allows reliable in vivo measurement of cavity dimensions and assessment of acute alterations in stroke volume in normal rats.

Animals↗
PubMed1992

Slow kinetic property of mexiletine in guinea pig atrium.

We studied the onset and offset of use-dependent block (UDB) of maximum rate of rise of action potential (Vmax) with 3 x 10(-5)M mexilietine in guinea pig left atrium. A large decrease of Vmax was observed between the first and the second excitation when the preparations were stimulated at 4Hz after two minutes of rest period. UDB after the second excitation developed slowly to reach steady state within 30 sec. These two onset rates were 1.016 +/- 0.055 and 0.070 +/- 0.009/action potential. Recovery process was also fitted with two exponential equations. The time constant of the fast recovery was 528 +/- 23 msec. and the slow one was 3099 +/- 435 msec. The relative contribution of the slow component was 38.3 +/- 2.6% in the onset and 29.7 +/- 3.1% in the recovery. In spite of elevated maximum diastolic potential at 4 Hz stimulation, the relationship between resting membrane potential and Vmax disclosed voltage-dependent block of Vmax was no more than 5%. It is concluded that mexiletine has a slow kinetic component as well as a fast one. When atrial muscle is depolarized, Vmax decreases further. Therefore, mexiletine may be more effective against the atrial arrhythmias than predicted previously.

Action Potentials↗
PubMed1992

Disuse atrophy of the left ventricle in chronically bedridden elderly people.

In the elderly cardiac size and function are determined by their level of physical activity. In this study, we assessed by echocardiography, the anatomic and physiologic changes of the heart in 28 elderly patients who had no cardiac disease and who were chronically bedridden. The data obtained were compared to those obtained from a control group of 38 age and sex matched elderly people whose activities had not been restricted. Chronically bedridden patients had markedly smaller left ventricular dimensions in both end-diastole and end-systole and smaller left atrial dimensions than did control subjects (3.7 +/- 0.7 vs 4.7 +/- 0.6 cm, p less than 0.001, 2.4 +/- 0.8 vs 2.9 +/- 0.7 cm, p less than 0.02 and 3.2 +/- 0.5 vs 3.8 +/- 0.9 cm, p less than 0.01, respectively). Though the wall thickness of the interventricular septum did not differ between the study groups, the left ventricular posterior walls of the bedridden group were significantly thinner than in the control group (0.8 +/- 0.2 vs 1.0 +/- 0.2 cm, p less than 0.01). The bedridden group had a significantly lower stroke index (26.9 +/- 6.2 vs 47.0 +/- 11.1 ml/m2, p less than 0.001) and cardiac index (1.84 +/- 0.52 vs 3.15 +/- 0.63 l/min/m2, p less than 0.001) than did the control group. Left ventricular mass index and left ventricular systolic stress were significantly lower in bedridden patients than in control subjects (88.0 +/- 18.1 vs 143.5 +/- 30.9 g/m2, p less than 0.001, and 135.9 +/- 4.9 vs 186.6 +/- 35.7 10(3) dynes/cm2, p less than 0.001, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

The beta-adrenergic receptor/adenylate cyclase system in the cardiac ventricles of a hypertrophic cardiomyopathy rat model.

The WKY/NCrj rat strain is considered to be a good animal model for hypertrophic cardiomyopathy (HCM). The purpose of this study was to examine the beta-adrenergic receptor/adenylate cyclase system in the cardiac ventricles of these rats. beta-adrenergic receptor density (Bmax) in the right ventricle (RV) was higher in WKY/NCrj than in Wistar rats. In contrast, Bmax in the interventricular septum (IVS) was lower in WKY/NCrj than in Wistar rats. Isoproterenol-stimulated adenylate cyclase activity in cardiac ventricular slices showed that changes corresponded to the changes of Bmax in every type of studied cardiac ventricle. The intracellular adenylate cyclase pathway (GTP gamma S-, NaF- and forskolin-stimulated adenylate cyclase activity in cardiac ventricular particulate fraction) did not differ between WKY/NCrj and Wistar rats in any region of the cardiac ventricles. Catecholamine levels tended to be low in the RV and to increase in the IVS of WKY/NCrj rats. Our results suggest that the activity of the beta-adrenergic receptor/adenylate cyclase system varies in different cardiac ventricles of the WKY/NCrj rat model for HCM.

Adenylyl Cyclases↗
PubMed1992

Echo/Doppler diagnosis of tetralogy of Fallot, ventricular septal defect, pulmonary valve dysplasia, and hypertrophic cardiomyopathy in WKY/NCrj rats.

We examined the hearts of 97 WKY/NCrj rats, a strain which spontaneously develops congenital cardiac malformations, by means of echocardiography with a pulsed Doppler ultrasound, and compared the results with those of 20 WKY/Ta rats and 30 normal Wistar rats. Dissection of these WKY/NCrj rats revealed a ventricular septal defect (VSD) in 20 and pulmonary valve dysplasia (PVD) in 41, both VSD and PVD occurring together in 18. VSD was readily diagnosed in vivo by the jet flow signal derived from the left-to-right shunt near the membranous portion, with a sensitivity of 85% and a specificity of 99%. Ultrasound imaging revealed overriding of the aorta and right ventricular (RV) hypertrophy in 18 of the 20 rats with VSD. Of the 20 rats with VSD, 10 had a systolic high-velocity jet across the RV outflow indicating an infundibular stenosis. PVD was commonly accompanied by a pulmonary regurgitation signal, with severe cases showing intensified echo and low excursion of the cusps. The regurgitation signal showed a good diagnostic value for PVD with a sensitivity of 82% and a specificity of 85%. In the remaining 54 WKY/NCrj rats without VSD or PVD, the ratio of mean left ventricular (LV) wall thickness to cavity dimension, the fractional shortening of the LV dimension, and the septal to LV free wall thickness ratio were all abnormally high, and the motion of the ventricular septum was reduced in most of the cases compared with that of the other two strains. All these features resemble the hypertrophic cardiomyopathy seen in humans, which further promises that the rats should be a useful model for the controversial disease.

Animals↗
PubMed1992

Percutaneous transluminal coronary angioplasty in a patient with Kawasaki disease. A case report of an unsuccessful angioplasty.

A 13-year-old boy with severe coronary stenosis due to Kawasaki disease underwent percutaneous transluminal coronary angioplasty (PTCA). The guide wire and the balloon catheter easily passed through the stenosis in the left anterior descending artery. However, effective dilatation could not be achieved even when the balloon size was increased to 2.5 mm in diameter. We discontinued further inflation of the balloon because serious resistance was encountered on withdrawal of the balloon catheter. In patients with Kawasaki disease, the value of PTCA as a treatment for coronary stenosis is questionable.

Adolescent↗
PubMed1992

[Regional myocardial coronary blood flow reserve in hypertrophic cardiomyopathy assessed by digital subtraction coronary angiography].

Using digital subtraction coronary angiography (DSA), we evaluated the regional myocardial coronary blood flow reserve (rMFR) in 18 patients with hypertrophic cardiomyopathy (HCM). There were 13 patients with asymmetrical septal hypertrophy (ASH), and 5 with asymmetrical apical hypertrophy (AAH). Eight subjects without apparent cardiac abnormality served as controls. Relations between the rMFR and regional wall thickness as determined by echocardiography were also investigated. Peak contrast density (Cm) and time to Cm (Tm) were measured from digital angiograms at the middle and distal ventricular septum (VS) and at the apical and left ventricular posterior wall (PW). The rMFR of each region of interest was expressed as the ratio of Cm/Tm at the baseline and at peak hyperemic response induced by intracoronary administration of papaverine. The rMFR was significantly lower at the VS and apex in HCM than in controls: middle VS, 1.9 +/- 0.5 vs 3.9 +/- 0.5, p < 0.001; distal VS, 2.0 +/- 0.5 vs 4.4 +/- 0.9, p < 0.001; and the apex, 2.0 +/- 0.7 vs 4.5 +/- 1.6, p < 0.01. However, it did not differ at the PW; 2.6 +/- 0.9 vs 3.0 +/- 0.9 between the 3 groups. The middle VS and apex, where the wall was the thickest, had the lowest rMFR in ASH and AAH. Furthermore, at the VS and apex, a curvilinear relationship was observed between the rMFR and wall thickness (rMFR = -0.88 in WT + 2.39, r = -0.57, p < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Extent and degree of coronary flow reserve in hypertrophic cardiomyopathy assessed by delta Fract map unfolding coronary flow reserve index].

Patients with hypertrophic cardiomyopathy (HCM) are known to have ischemic events and decreased coronary flow reserve, but the variabilities in the site and degree of fall between patients with this disease have not been clarified. To elucidate these variabilities, we performed exercise myocardial single photon emission computed tomography (SPECT) using double dose method in 30 patients with HCM (6 with obstruction, 17 with non-obstruction, 7 with apical hypertrophy) and 10 normals. Then, the delta Fract (coronary flow reserve index) map was obtained for each subject. Exercise and then rest Tl-201 myocardial scintigraphy were performed after administration of Tl-201. The data were reconstructed, making the circumferential curves from the same level of short-axis imaging during exercise and at rest. By subtracting the values at rest from the values during exercise, which were divided by the values at rest, delta Fract in each frame was obtained, and described on the unfolded map. The extent and degree of coronary flow reserve were visually estimated by this delta Fract map. Patients were categorized into 5 groups: diffuse fall of coronary flow reserve (D-type), 6 cases; localized fall of the septum or lateral wall (L-type), 5 cases; fall of apical region (A-type), 5 cases; mild fall (M-type), 6 cases; and normal pattern (N-type), 8 cases. We concluded that delta Fract map is useful for evaluating the extent and degree of coronary flow reserve in HCM.

Adult↗
PubMed1992

The effect of percutaneous transluminal coronary angioplasty on anaerobic threshold in patients with angina pectoris.

The anaerobic threshold (AT) is regarded an objective parameter for evaluating exercise tolerance, but its relationship to the improvement of myocardial ischemia remains uncertain. To investigate this relationship, submaximal treadmill exercise tests were performed for 15 consecutive patients with angina pectoris who had undergone successful percutaneous transluminal coronary angioplasty (PTCA). Before and after PTCA, the AT was determined using cardiorespiratory monitoring, while the patients were receiving their usual vasodilator medications. 1) Before PTCA, the minute oxygen uptake (VO2) at the AT correlated well with the peak VO2 (r = 0.92, p < 0.002). The VO2 at the AT, however, showed less correlation (r = 0.71, p < 0.002) with the VO2 at ST segment depression, while the latter parameter correlated closely with the peak VO2 (r = 0.91, p < 0.002). 2) After PTCA, exercise time, peak VO2, and the double product at peak exercise increased significantly (from 640.1 +/- 212.2 to 772.9 +/- 230.0 sec, p < 0.001, from 19.1 +/- 5.2 to 22.4 +/- 4.9 ml/min/kg, p < 0.05, and from 19.7 +/- 5.0 x 10(3) to 23.7 +/- 4.5 x 10(3), p < 0.001, respectively). However, the VO2 at the AT did not increase significantly (from 15.8 +/- 4.1 to 16.6 +/- 3.5 ml/min/kg, p = NS). The heart rate, systolic blood pressure, and double product at the AT did not change significantly. In conclusion, in patients with angina pectoris, the AT is apparently related to the onset of myocardial ischemia. However, the AT does not necessarily reflect acute improvement of myocardial ischemia immediately after PTCA.

Aged↗
PubMed1992

[Electrophysiologic effects of flecainide on guinea pig atrium].

We investigated the effects of flecainide on guinea pig atrial muscle. Using Langendorff's method, the whole heart of a guinea pig was perfused with Tyrode's solution containing acetylcholine (3 x 10(-7) M). Then, with right atrial extrastimulus and high frequency pacing method, the following values were measured before and after administration of flecainide (10(-7)-10(-5) M). A) Effective refractory period (ERP); the longest coupling interval which failed to produce right atrial activity at premature stimulus. B) Interatrial conduction time (ACT); After right atrial stimuli by trains at PCL 200 ms for 5 min the interval from the stimulation to the first deflection of the left atrial activity. C) Atrial fibrillation threshold (AFT); the minimal amount of current required to induce atrial fibrillation lasting for more than 30 sec by 50 Hz high frequency stimulation. Flecainide lengthened ERP (> or = 3 x 10(-5) M) and ACT (> or = 10(-7) M). Flecainide (10(-5) M) significantly increased AFT which correlated well with ERP (r = 0.81, p < 0.002) and ACT (r = 0.84, p < 0.002). In conclusion these effects of flecainide on guinea pig atrium might explain in part the clinical effectiveness of the drug on paroxysmal atrial fibrillation.

Animals↗
PubMed1992

[Ultrasonic tissue characterization in hypertrophic cardiomyopathy: analysis of three-layered appearance of the ventricular septum by apical approach].

In normal hearts, two-dimensional echocardiography from the apical window displays the left ventricular wall as a three-layered appearance (TLA): central bright layer and bilateral sonolucent zones. The TLA is considered to reflect the normal myocardial architecture: the predominant latitudinal fiber bundles of the midwall layer, and longitudinal or oblique ones on both sides. We analysed the TLA of the ventricular septum in 20 normal subjects, 20 patients with left ventricular hypertrophy due to pressure load (LVH), and 81 patients with hypertrophic cardiomyopathy (HCM). Of the 81 HCM patients, the layering was often obscure or absent in 53 (65%), whereas LVH patients showed clear TLA as well as normal hearts. In patients with severe layering disorder (n = 30), the age at diagnosis was lower (40 +/- 15 vs 50 +/- 12, p less than 0.05), and familial occurrence (53 vs 11%, p less than 0.01) and severe functional limitation (NYHA greater than or equal to III) were more common (27 vs 4%) than in those with clear TLA (n = 28). The disturbed layering detectable by echocardiography may reflect the disorder of basic myocardial fiber architecture in the ventricular septum, and is likely to become a useful marker of the pathologic severity of the disease.

Adult↗
PubMed1992

[Clinical evaluation of 123I-BMIPP myocardial scintigraphy in patients with hypertrophic cardiomyopathy].

123I-BMIPP myocardial scintigraphy was performed in 13 patients with hypertrophic cardiomyopathy and compared with 201Tl myocardial scintigraphy performed within 3 months for evaluating the clinical significance of 123I-BMIPP myocardial scintigraphy. SPECT images were divided into 13 segments and segmental images were visually scored on a 4 (increased tracer uptake) to 0 (severely decreased tracer uptake) scale according to the tracer uptake. In comparison of 123I-BMIPP early images and 201Tl perfusion images, mismatches were seen in about 70% of all segments. The number of segments demonstrating lower myocardial uptake of 123I-BMIPP was larger than that of 201Tl. In hypertrophic regions, the tracer uptake of 123I-BMIPP early images was significantly lower than that of 201Tl images and the lower uptake of 123I-BMIPP delayed images was more marked. In non-hypertrophic regions, no significant difference was seen between the tracer uptakes of 123I-BMIPP early images and 201Tl images but the tracer uptake of 123I-BMIPP delayed images was significantly lower than that of 201Tl images. The mismatch between the tracer uptakes of 123I-BMIPP images and 201Tl images was thought to be a reflection of disordered myocardial fatty acid metabolism. "Washout", the difference between the tracer uptakes of 123I-BMIPP early images and delayed images was also thought to be a reflection of disordered myocardial fatty acid metabolism. These results suggest that 123I-BMIPP is a promising radiopharmaceutical for evaluating disordered myocardial fatty acid metabolism in patients with HCM.

Cardiomyopathy, Hypertrophic↗
PubMed1991

Prolonged atrial activity due to delayed conduction in the atrium of patients with paroxysmal atrial fibrillation.

We investigated the relationship between the duration of electrical atrial activity and intra-atrial conduction time to determine whether the prolonged atrial activity was due to delayed conduction in the human atrium. The study included 15 patients with paroxysmal atrial fibrillation (PAF) and 15 control patients. The duration of atrial electrical activity was measured by selecting a minimum electrographic amplitude of 50 microV. In patients with PAF, the duration of atrial activity was prolonged in proportion to the delay of interatrial conduction time from the high right atrium to the coronary sinus as the coupling interval of premature extrastimuli was decreased. Both the fragmented atrial activity zone and the interatrial conduction delay zone were wider in patients with PAF than in control patients. It is concluded that assessment of the duration of atrial activity with a minimum amplitude of 50 microV is useful in evaluating human atrial vulnerability since it reflects the atrial conduction delay in patients with PAF.

Adolescent↗
PubMed1991

Effect of cardiac sympathetic nerve stimulation on acutely ischemic myocardium--a comparison with the response to exogenous noradrenaline.

To assess the integrity of an adrenergic nervous function in acute myocardial ischemia, the contractile response of the ischemic region to cardiac sympathetic nervous stimulation (CSNS) was measured in comparison that with to exogenous noradrenaline (NA) infusion. In 13 anesthetized open chest mongrel dogs, haemodynamic changes, segmental wall motion, and the concentration of NA in the efferent coronary vein were measured. CSNS was performed by electrically stimulating the left ansa subclavia. Data concerning baseline values, values during CSNS, and those obtained during NA infusion both before and up to 5 h after coronary occlusion were compared. Regional myocardial blood flow of the ischemic region was also measured using the H+ clearance method. Systolic expansion with coronary occlusion was not changed or augmented by CSNS. However, improvement was observed in all experiments when NA infusion was used. The percent change of systolic shortening, indicating the response of segmental wall motion to CSNS, decreased soon after occlusion, recovered temporarily within 30 min after occlusion, but did not improve throughout the period after 60 min. The decrease of NA overflow into the efferent vein by CSNS showed a biphasic pattern; reduction occurring immediately after occlusion and again 3-5h after occlusion. Throughout these experimental studies it was considered that the preserved responses to the exogenous injected NA represented the contribution of presynaptic factor.

Animals↗
PubMed1991

Visualization of the heart and determination of left ventricular mass in rats by echocardiography.

A high-frequency transducer was used to determine the optimal parameters for visualizing the heart in 40 normal Wistar, 15 SHR, and 10 aorta-banded rats. The rats were 5 to 30 weeks old and weighed between 105 and 705 grams. Two-dimensional and M-mode views of the ventricles, atria, valves, and great arteries were obtained by placing the transducer beneath the rats through the left or right parasternal window in either the prone or the right decubitus positions, respectively. Left ventricular (LV) mass was determined on the basis of a spheroid model; these values correlated well with the LV weight for both the Wistar rats (r = 0.94, p less than 0.001) and the rats with cardiac hypertrophy due to pressure load (r = 0.87, p less than 0.001). These results were highly reproducible. This indicates that echocardiography is useful for obtaining quantitative measurements in rats.

Animals↗