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Biomedical subjects

T Kumada

Publications and source records attributed to T Kumada.

At least 181 records · Page 10Linked to original sources
PubMed1982

Isoproterenol-induced myocardial dysfunction in dogs with coronary stenosis.

Stress-induced regional myocardial ischemia in the presence of mild coronary stenosis was studied in five dogs 2-4 wk after implantation of pairs of ultrasonic crystals to measure left ventricular wall thickening (% delta WT) and subendocardial segmental shortening (% delta L). Isoproterenol (0.2 micrograms.kg-1.min-1) was infused before and after production of coronary stenosis, which produced no resting dysfunction. During isoproterenol infusion with coronary stenosis % delta WT and subendocardial % delta L were significantly decreased although blood flow was comparable to conditions at rest, indicating that the demand for blood flow exceeded supply. Linear regression analysis of mean transmural blood flow versus % delta WT during isoproterenol demonstrated that wall thickening was significantly related to changes in mean blood flow: y (percentage wall thickening) = 27.5 X (transmural blood flow) -8.2 (r = 0.83); likewise % delta L was significantly related to subendocardial blood flow during isoproterenol infusion: y (percentage shortening) = 17.1 X (subendocardial blood flow) -0.4 (r = 0.85). These results indicate that both regional % delta WT and % delta L sensitively reflect the adequacy of myocardial perfusion even during stress-induced changes in myocardial O2 demands and blood flow.

Animals↗
PubMed1982

Comparison of postpacing and exercise-induced myocardial dysfunction during collateral development in conscious dogs.

In 10 conscious dogs, a model was developed for studying regional contractile responses in a coronary collateral-dependent bed. Regional myocardial function was compared after terminating a maximum paced rate of 240 beats/min maintained for 3 minutes (postpacing period) with that during telemetry-monitored exercise at comparable heart rates (average 252 +/- 34 beats/min, duration 2.4 minutes) at different times during collateral development. Ultrasonic dimension gauges were used to measure control and ischemic segment (CS and IS) lengths and ischemic zone regional wall thickness (IW). An ameroid constrictor and a Doppler flow probe were placed around the left circumflex coronary artery, and pacing electrodes were sutured to the right ventricle. An average of 23 days postoperatively, coronary obstruction was complete. Studies at that time showed that percent shortening (% delta L) of IS and percent wall thickening (% delta W) of IW decreased after pacing to 57% and 35% of control, respectively, and during exercise to 37% of control. One week later (average 30 days postoperatively), significant depression of regional function no longer occurred postpacing. However, exercise at a comparable heart rate still provoked regional dysfunction in the collateral-dependent zone: Both IS% delta L and IW% delta W decreased to 51% of control. Regional function at rest did not differ during these studies. Thus, the effectiveness of the postpacing response for detecting limited collateral reserve was eliminated by further collateral development, but regional myocardial dysfunction during exercise stress served to detect ischemia despite increased collateral circulation.

Animals↗
PubMed1982

Assessment of left ventricular relaxation in the diseased heart in man.

To examine the exponential nature of the left ventricular pressure (LVP) fall during isovolumic relaxation (IRP) in 59 patients (normal (N), 6; angina pectoris (AP), 13; myocardial infarction (MI), 24; and congestive (CCM, 6) and hypertrophic (HCM, 10) cardiomyopathies), LVP and dP/dt were measured by a Millar's catheter-tipped transducer. In P vs time relation during IRP was reasonably fitted by a straight line (r greater than 0.97) in all cases. Time constant (msec) in CCM (56.9 +/- 10.7), HCM (44.8 +/- 12.4) and MI (43.8 +/-7.4 higher (p less than 0.05) than in N (30.3 +/- 5.5), and peak (-) dP/dt (mmHg/sec) was lower (841 +/- 171, 1152 +/- 397 and 1270 +/- 211, respectively; p less than 0.05) than in N (1885 +/- 150), suggesting impaired LV relaxation in these groups. However, (-) dP/dt upstroke pattern was exponential only in both N and 8 of the AP. The (-) dP/dt upstroke in the remaining groups lost its exponential nature, showing rather a down ward-convex curvature which was especially prominent in CCM. This indicates non-exponential fall of LVP during IRP. Thus, the present results suggest that impaired relaxation disturbs the exponential nature of LV relaxation.

Adult↗
PubMed1982

[Study on right and left atrial dynamics in chronic constrictive pericarditis by esophageal echocardiography].

In 9 normal subjects (N) and 4 patients with chronic constrictive pericarditis (CP) with normal sinus rhythm, esophageal echocardiography was performed to obtain simultaneous echograms of the right atrial free wall and the interatrial septum, and both atrial dynamics were evaluated. In spite of increased mean right atrial and mean pulmonary arterial wedge pressures in CP, there were no significant differences in left, right and total atrial end-diastolic dimensions between N and CP. This indicates that there is a decrease in compliance of atrio-pericardial system in CP. Atrial shortening of both atria during active atria contraction was decreased in CP, while there was no significant difference in atrial dimension measured at the beginning of the active atrial shortening between N and CP. This impaired pump function might be due to increased ventricular late-diastolic pressure or organic change in the atrial muscle. The passive enlargement of both atria was impaired during atrial filling phase in CP. Thus, it was concluded that in CP the active shortening and passive enlargement of the right and left atria are decreased, and the atria tend to be a conduit.

Adult↗
PubMed1982

[Diagnosis of right atrial infarction by esophageal echocardiography].

Atrial infarction is rare and its ante mortem diagnosis is difficult by electrocardiography. There has been no report concerning the diagnosis of atrial infarction by echocardiography because it is difficult to observe atrial motion by conventional echocardiography. This report deals with a case of probable right atrial infarction diagnosed by esophageal echocardiography. A 50-year-old man was admitted to our hospital under the diagnosis of acute infero-posterior myocardial infarction. Swan-Ganz catheterization data revealed dip and plateau pattern with elevated right atrial pressure suggesting complicated right ventricular infarction. In the esophageal echocardiograms recorded one month later, the motion of the right atrial anterior wall was akinetic and right atrial dimension did not change during both atrial contraction phase and atrial filling phase. These findings suggest impairment of pump function and reservoir function of the right atrium. Amplitudes of the interatrial septum during atrial filling phase and atrial contraction phase were in the lower limit of normal range. Total occlusion of the right coronary artery was proven by coronary arteriography. Hypokinesis of the upper right atrial appendage was suspected by right atriography and maximal right atrial volume was as large as 116 ml. In the right atrial volume curve by cardiac scintigraphy, fractional emptying was as low as 28%. The patient had an uneventful recovery and returned to full-time works, so that pathological diagnosis was not obtained, but the clinical diagnosis of right atrial infarction was strongly suspected by the clinical findings mentioned above. It was concluded that the esophageal echocardiography is mandatory to observe atrial wall motion abnormality whenever atrial infarction is suspected.

Echocardiography↗
PubMed1981

Esophageal echocardiographic left ventricular anterolateral wall motion in normal subjects and patients with coronary artery disease.

Esophageal echocardiography was developed for recording left ventricular anterolateral wall (LVAW) echocardiograms and was applied clinically to 14 normal subjects and 21 patients with coronary artery disease. LVAW echocardiograms were obtained satisfactorily in 11 of 14 normal subjects (75%) and 20 of 21 patients (95%) with coronary artery disease. LVAW echocardiograms were obtained by conventional anterior echocardiography in eight of 21 patients (38%) with coronary artery disease. In 11 normal subjects, mm/sec (mean 34.3 +/- 5.2 mm/sec); and diastolic wall thickness ranged from 9-12.5 mm (mean 11.2 +/- 0.7 mm). In 20 patients with coronary artery disease, LVAW motion obtained by esophageal echocardiography was classified into five groups according to the excursion, and the findings were in good agreement (80%) with those obtained by left ventriculography. Classification of LVAW motion by conventional echocardiography agreed with that of left ventriculography in only three of eight patients, although all eight patients had abnormal LVAW motion by the conventional method. In all patients except one, whose LVAW echocardiograms were obtained by conventional echocardiography, excursion was much less than that obtained by esophageal echocardiography. We conclude that the projection of an ultrasonic beam from the intraesophageal transducer is a better approach for accurate measurement of LVAW motion.

Adult↗
PubMed1981

[Exercise echocardiography: interventricular septal thickness and motion in patients with effort angina during ergometer exercise (author's transl)].

To detect abnormal interventricular septal (IVS) motion during exercise-induced ischemia, ergometer exercise echocardiography was performed using a specially devised transducer in 12 patients (pts) with effort angina (left anterior descending artery disease) and 10 normal subjects (N) at rest, and during exercise and recovery. During exercise, percent systolic IVS thickening (% delta T) and IVS excursion (Ex) increased from 52 +/- 13% at rest to 73 +/- 19% and from 7.0 /- 1.3 mm at rest to 10.6 +/- 1.9 mm, respectively, in N, and also from 52 +/- 23% to 67 +/- 36% and from 7.3 +/- 1.9 mm to 9.7 +/- 2.1 mm in all of 3 pts with distal left anterior descending artery disease. On the other hand, in 9 pts with proximal left anterior descending artery disease, % delta T and Ex during exercise decreased from 41 +/- 17+ at rest to 26 +/- 25% and from 7.7 +/- 1.2 mm to 5.1 +/- 4.6 mm. The late systolic wall thickening of IVS was observed during peak exercise in 2 of the 9 pts, one of whom exhibited systolic IVS thinning and a decrease in diastolic thickness (from 6 mm to 4.5 mm). In 5 pts with IVS asynergy during exercise diastolic IVS thickness increased maximally from 10.2 +/- 3.3 mm at rest to 11.4 +/- 3.5 mm during recovery (reactive hyperemia). Exercise echocardiography is useful to predict the location of left anterior descending artery disease and to evaluate IVS performance during exercise-induced ischemia.

Adult↗
PubMed1981

[Exercise echocardiography: II. Interventricular septal wall dynamics in patients with left anterior descending coronary disease during recovery (author's transl)].

Supine ergometer exercise test was performed in 10 healthy subjects and 9 patients who had severe stenosis in the left anterior descending coronary artery [5 patients with stenosis proximal to the septal perforator (proximal LAD disease) and 4 patients with stenosis distal to the septal perforator (distal LAD disease)]. In healthy subjects and patients with distal LAD disease, the increment of septal excursion (IVS Ex) and percent systolic thickening of the septum (% delta Th) during exercise returned to the pre-exercise level with a few minutes after exercise. In patients with proximal LAD disease, IVS Ex decreased to 1.4 +/- 1.2 mm during exercise form the pre-exercise level (7.4 +/- 0.7 mm) and % delta Th decreased to 6.4 +/- 5.1% during exercise from the pre-exercise level (37.2 +/- 8.4%). After exercise, IVS Ex and % delta Th increased to 8.6 +/- 0.9 mm at 2 min and 38.0 +/- 9.8% at 3 min respectively and then returned to the pre-exercise level. End-diastolic wall thickness (WTh) did not change during and after exercise in healthy subjects and patients with distal LAD disease, while in patients with proximal LAD disease, WTh increased for a few minutes after exercise and returned to the pre-exercise level. The change of electrocardiogram and symptom of angina pectoris lasted longer than the abnormal wall motion.

Adult↗