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Biomedical subjects

T Kashima

Publications and source records attributed to T Kashima.

At least 91 records · Page 5Linked to original sources
PubMed1984

[An experimental study on the relationship between interventricular septal echograms and interventricular pressure gradient].

To evaluate the correlation between the configuration and motion of the interventricular septum (IVS) and the interventricular pressure gradient, six closed-chest dogs were studied. M-mode and two-dimensional echograms, the left (LVP) and right ventricular pressures (RVP), the interventricular pressure gradient (LVP-RVP), phonocardiograms in the left and right ventricles and electrocardiograms were simultaneously recorded. The RVP was gradually elevated by injecting Lycopodium in a peripheral vein. In all six dogs, there were good correlations between the curvature of the IVS and the interventricular pressure gradient in end-systole and in end-diastole. In M-mode echograms of the IVS, three dips were recognized in early diastole (isovolumetric relaxation period, D1 dip), in late diastole (atrial kick, D2 dip) and in early systole (isovolumetric contraction, S1 dip) when the RVP was elevated. Three negative dips on interventricular pressure gradient curves were observed to occur simultaneously with D1, D2, and S1 dips, respectively. A D1 dip was demonstrated in all six dogs, a D2 dip in four dogs, and an S1 dip in six dogs. In conclusion, the curvature of the IVS reflects the change in the interventricular pressure gradients in diastole as well as in systole. D1, D2 and S1 dips in the IVS echogram also reflect changes in the interventricular pressure gradients.

Animals↗
PubMed1983

A regurgitant jet and echocardiographic abnormalities in aortic regurgitation: an experimental study.

Acute aortic regurgitation was created experimentally in 21 mongrel dogs to examine the relationship of the regurgitant jet to observed echocardiographic findings. The direction of the regurgitant jet was studied by echo contrast injections in the aortic root. Diastolic fluttering of the anterior mitral leaflet (AML) was noted in all 21 dogs irrespective of direction of the jet. Diastolic fluttering of the interventricular septum (IVS) was noted in six of the seven dogs with a tear of the noncoronary cusp and in one of seven dogs with lesions in the left coronary cusp. In all seven dogs with echocardiographically demonstrated IVS fluttering, a regurgitant jet impinged on the anterior part of the IVS. Amplitude of the AML excursion was not significantly different from control when the lesions involved the noncoronary or the left coronary cusps. However, all seven dogs that had a lesion in the right coronary cusp demonstrated a significant reduction in the amplitude of the AML excursion. The regurgitant jet in these dogs impinged uniformly on the AML. We conclude that diastolic fluttering of the AML is uniformly observed and unrelated to the direction of the regurgitant jet, diastolic fluttering of the IVS is caused by the regurgitant jet impinging upon the IVS, and amplitude of the AML may be reduced as a result of a jet impingement of the AML.

Animals↗
PubMed1982

The effect of digoxin on cardiovascular responses to hypoxia and reoxygenation in anesthetized dogs.

To clarify the efficacy of digitalis in acute hypoxia and reoxygenation, we estimated the effects of digoxin on cardiovascular hemodynamics in anesthetized dogs. Hypoxia caused significant increases in aortic pressure, pulmonary artery pressure, left ventricular (LV) pressure, rate of change in LV pressure (LVdp/dt), cardiac output (CO) and plasma catecholamines. These changes in LVdp/dt, CO and plasma catecholamines induced by hypoxia were returned to the control levels within 3 min by reoxygenation with 70% O2. The injection of digoxin (0.05 mg/kg) in hypoxic dogs resulted in significant increases in LVdp/dt, CO and stroke volume (SV) but no changes in levels of plasma catecholamines, heart rate, mean aortic pressure and mean pulmonary artery pressure. However, the injection of digoxin resulted in no significant changes in cardiovascular response to reoxygenation. Our experiments demonstrate that digoxin caused significant increases in CO, SV and LVdp/dt in dogs with hypoxia but resulted in no significant changes in cardiovascular responses to reoxygenation.

Anesthesia↗
PubMed1982

Variant angina induced by alcohol ingestion.

A 49-year-old man had episodes of angina pectoris in the middle of the night only when he had ingested alcoholic beverage in the evening. Electrocardiograms at rest and after exercise were completely normal. An anginal attack with remarkable ST elevation in leads V1 through V5 was successfully provocated every night when he ingested alcohol and no attacks occurred when he did not take alcohol. The decay curve of ethanol concentration in blood after the ingestion of alcohol was normal. A coronary arteriography revealed 50% stenosis of the proximal portion of the left anterior descending artery, 50% stenosis of the distal portion of the left circumflex artery and the normal right coronary artery. It was suggested that the direct effect of ethanol was not responsible to his attack because the ethanol level at the time of the attack was quite low, but autonomic imbalances resulted from the late effects of alcohol ingestion might be responsible to the spasm of the coronary artery. We report a patient with Prinzmetal's variant angina in whom attacks were induced only in the night when he ingested alcoholic beverage. Only one report of such a case was bibliographically found and this is the second case with variant angina induced by alcohol ingestion.

Angina Pectoris, Variant↗
PubMed1981

Electrocardiographic changes induced by the stellate ganglion block in normal subjects.

In order to examine the laterality of the sympathetic control of the human heart, electrocardiographic changes induced by a unilateral stellate ganglion block (SGB) were observed. 10ml of 1% lidocaine was used for the block and post-block ECG was recorded just after the appearance of Horner's sign. Patients who developed vocal hoarseness were excluded. 15 recordings of 14 subjects with right SGB and 16 recordings of 12 subjects with left SGB were used for analysis. A significant increase in the P-P interval from 0.90 +/- 0.17 sec to 0.96 +/- 0.16 sec. was observed only with right SGB and the predominance of the right side in the sympathetic nervous control of the human heart was thus demonstrated. The atrioventricular conduction time was not affected by either the right or left SGB. The QTc was slightly but significantly prolonged only by the right SGB, from 0.40 +/- 0.04 sec. to 0.43 +/- 0.04 sec. This prolongation was not large enough to support a definite conclusion and further investigations should be made.

Adult↗
PubMed1981

Effects of hypoxia on myocardial digoxin uptake and levels of plasma catecholamines in anaesthetised dogs.

The effect of hypoxia on digoxin pharmacokinetics, myocardial digoxin uptake and levels of plasma catecholamines in dogs was studied to clarify the mechanism of enhanced sensitivity to digitalis in hypoxia. Sixteen mongrel dogs were anaesthetised and artificially respired; eight with room air, eight with 8% oxygen in nitrogen, and digoxin (0.05 mg . kg-1) was intravenously given to each dog. There was no difference between hypoxic and non-hypoxic dogs in pharmacokinetic curves of digoxin. The level of myocardial digoxin in hypoxic dogs was significantly lower than that in non-hypoxic dogs. The level of plasma adrenaline in hypoxic dogs was significantly higher than that in non-hypoxic dogs (P less than 0.01). These data suggest that enhanced sensitivity to digoxin in hypoxia may be attributable not to abnormal digoxin pharmacokinetics or increased myocardial digoxin uptake but partly to higher levels of plasma catecholamines.

Animals↗
PubMed1981

Hemodynamic determinants of pulmonary valve motion during systole in experimental pulmonary hypertension.

To clarify the determinants of pulmonary valve (PV) motion in pulmonary hypertension, we examined the correlations among PV echo patterns, the pulmonary artery (PA) flow curve just above the PA orifice and the pulmonary artery-right ventricle (PA-RV) pressure gradient. By constricting the PA, we could produce a variety of PV echo patterns, including midsystolic semiclosure in open-chest dogs. Throughout the experiments, the PV echo pattern and PA flow curve were similar in pattern and timing. When the PV echo showed midsystolic semiclosure with reopening. The PA flow curve showed a transient decrease followed by a transient increase during midsystole. The PA-RV pressure gradient became transiently positive (PA pressure greater than RV pressure) and then negative in midsystole only when the PV echo showed midsystolic semiclosure with reopening. In conclusion, PV motion during systole may be instantaneously determined by PA flow change and the PA-RV pressure gradient during the cardiac cycle in experimental pulmonary hypertension.

Animals↗
PubMed1980

Diastolic bulging of the interventricular septum toward the left ventricle. An echocardiographic manifestation of negative interventricular pressure gradient between left and right ventricles during diastole.

Diastolic bulging of the interventricular septum (IVS) toward the left ventricle was observed by real-time cross-sectional echocardiography in three patients with primary pulmonary hypertension and one patient with secondary pulmonary hypertension after closure of an atrial septal defect. M-mode echocardiography showed a characteristic abnormal pattern of septal motion in diastole and in systole. In two patients, we attempted to correlate M-mode motion to the interventricular pressure gradient. During diastole, the interventricular pressure gradient between the left and right ventricles was negative and the pressure gradient curve was very similar to the M-mode echogram of the IVS. Banding studies in which acute right ventricular hypertension was produced in dogs showed similar shape changes, suggesting that the diastolic shape and motion of the septum are determined by the interventricular pressure gradient between the ventricles. Diastolic bulging of the IVS toward the left ventricle in our patients results from negative interventricular pressure gradient between the left and right ventricles during diastole.

Adult↗
PubMed1980

Motion of the interatrial septum in acute mitral regurgitation. Clinical and experimental echocardiographic studies.

The interatrial septal echocardiograms from 15 patients with acute mitral regurgitation due to ruptured chordae tendineae were compared with those from 14 normal subjects. On the cross-sectional echocardiogram, the interatrial septal configuration in patients with chordal rupture showed a characteristic pattern in which the interatrial septum (IAS) was flat or slightly convex toward the left atrium at end-diastole and became markedly convex toward the right atrium at end-systole. On the M-mode echocardiogram, the interatrial septal amplitude was greater in patients with chordal rupture (12.4 +/- 1.9 mm) than in normal subjects (9.4 +/- 0.9 mm). Systolic fluttering of the IAS was found in five of 10 patients with rupture of the chordae attached to the posterior mitral leaflet. This finding was thought to be specific for acute mitral regurgitation due to ruptured chordae to the posterior mitral leaflet. After operation, the amplitude of the IAS became normal or diminished and systolic fluttering of the IAS disappeared. Animal experiments performed to clarify the mechanism of these findings showed that increased systolic motion of the IAS resulted from an increased in the systolic left atrial-to-right atrial pressure gradient due to acute mitral regurgitation. The systolic fluttering of the IAS was thought to represent a jet stream against the IAS due to rupture of the chordae tendineae to the lateral half of the posterior mitral leaflet. We conclude that the interatrial septal echocardiogram reflects the hemodynamic changes due to acute mitral regurgitation and direction of the regurgitant jet against the IAS. This finding may prove to be important in diagnosing acute mitral regurgitation secondary to ruptured chordae tendineae.

Acute Disease↗
PubMed1980

Age-related differences in tolerance to digoxin. Lower digoxin concentration in myocardial microsomal fraction in infant rats.

To clarify the mechanism responsible for age-related differences in tolerance to digitalis, we studied the potassium contents of serum and myocardium and the digoxin concentrations of serum, myocardium, and myocardial microsomal fraction in infant and adult rats. While serum potassium concentration was the same in both infant and adult rats, the potassium content of myocardium found in the infant rats was significantly higher than that in the adult ones. Digoxin concentration of serum in infant rats was lower than that in the adult ones after a bolus injection of the same dose of digoxin per kilogram of body weight was given. Digoxin concentration of microsomal fraction, obtained 1 hour after the administration of 0.2 mg/Kg of digoxin in infant rats, was lower than that obtained 1 hour after the administration of 0.1 mg/Kg of digoxin in adult ones even though the digoxin concentrations of serum and myocardium in infant rats were significantly higher than those obtained in adult ones. Thus, less sensitivity to digitalis found in infant rats may be attributable to the higher potassium content of myocardium and the lower digoxin concentration of microsomal fraction.

Aging↗
PubMed1980

The effects of digoxin on resting membrane potentials of skeletal muscles in dystrophic mice.

To clarify the abnormality of skeletal muscles in dystrophic mice, we studied the potassium content, resting membrane potential and especially the effects of digoxin on the membrane potential. Both the potassium content and the resting membrane potential of dystrophic muscles were significantly lower than those of normal mice. The resting membrane potential of dystrophic muscles was less reduced by digoxin than that of normal mice. It was suggested that there was a change in membrane permeability of skeletal muscles in dystrophic mice and that membrane permeability was less sensitive to digoxin than normal mice.

Animals↗
PubMed1980

Favorable effects of oral digoxin therapy on the left ventricular performance in patients with artificial pacemakers.

The contribution of atrial systole in the left ventricular (LV) function and the effects of oral digoxin maintenance therapy on the LV function were evaluated noninvasively in patients who had artificial pacemakers but no clinical manifestation of congestive heart failure (NYHA Class I). Diastolic dimension (Dd), ejection time (ET), and stroke volume were constant in 8 patients without P waves on their electrocardiograms, but in 20 patients with P waves they were variable from beat to beat because of the variation of the PR intervals which caused them to reach their maximum values when the PR intervals were 160 to 200 msec. Ten out of the 28 patients were given 0.25 mg of digoxin daily for 10 days. Dd did not change significantly, but the ET and the systolic dimension were significantly shortened (P < 0.001). Posterior wall excursion, ejection fraction, and mean posterior wall velocity were significantly increased (P < 0.001). It is concluded that (1) atrial contraction is important to the LV function in patients with artificial pacemakers, and (2) that favorable effects on the LV function can be obtained by a small dose of digoxin administered to the patients who had artificial pacemakers but no congestive heart failure.

Adult↗