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Biomedical subjects

R Katori

Publications and source records attributed to R Katori.

At least 91 records · Page 5Linked to original sources
PubMed1981

Coronary artery constriction by oxygen breathing in patients with coronary disease.

This study was conducted to find whether or not oxygen breathing induces coronary vasoconstriction in diseased as well as in normal coronary arteries. Coronary angiograms were repeated in 14 patients with coronary artery disease during successive air and oxygen breathings and the diameters of the coronary arteries as displayed by film projection were measured and compared. Arterial oxygen tension was elevated from 91.3 +/- 16.8 to 457.2 +/- 26.5 mmHg by oxygen breathing but was not accompanied by any significant changes in mean arterial pressure. The diameters of coronary arteries without significant narrowing were reduced from 2.89 +/- 1.05 to 2.65 +/- 1.02 mm by oxygen breathing (a decrease of 8.9 +/- 7.0%) and that of coronary arteries distal to a narrowing of more than 50% was reduced from 2.24 +/- 0.53 to 2.02 +/- 0.57 mm (a decrease of 10.1 +/- 10.7%). These findings suggest that oxygen breathing and constrict a large coronary artery even if it has atherosclerotic lesions and the myocardium needs more flow.

Coronary Circulation↗
PubMed1981

[Change of left ventricular segment length by nitroglycerin measured by biplane coronary cineangiography in man (author's transl)].

Left ventricular size at different portions was evaluated following the administration of nitroglycerin to find whether there is any regional difference in the amount of shortening. In 6 patients with old myocardial infarction, biplane coronary cineangiograms were obtained before and after sublingual administration of nitroglycerin of 0.3 mg. The coordinates of the bifurcations of the left coronary artery at multiple sites were measured on the postero-anterior and lateral films and the spatial lengths (L) between any paired two points were calculated frame by frame covering one cardiac cycle. The maximum length (Lmax) was 63.2 +/- 3.1 (SE) mm before nitroglycerin as a whole and was 61.4 +/- 2.9 mm after nitroglycerin, showing no significant change. The minimum length (Lmin) also showed no significant change after nitroglycerin; from 56.1 +/- 2.9 to 54.9 +/- 2.6 mm. However, at the free wall, Lmax after nitroglycerin was reduced by 4.5 +/- 2.5%, and Lmax at the anterior septum was also reduced by 3.0 +/- 1.3%. Lmax at the base was unchanged after nitroglycerin. Lmin at the free wall and at the anterior septum were also reduced after nitroglycerin, 4.4 +/- 2.6 and 2.9 +/- 1.2%, respectively, and it was unchanged at the base. Since a reduction in the left ventricular size is effective in reducing myocardial oxygen demand and is effective in treating myocardial ischemia, it was suggested that nitroglycerin is more effective in relieving ischemia at the free wall and septum and less effective at the base.

Cineangiography↗
PubMed1980

Increases in coronary vascular resistance related to high arterial oxygen tension in dogs.

It is known that oxygen inhalation induces coronary vessel constriction as well as brings about a reduction in myocarial oxygen consumption. The present study was performed to clarify whether or not this constriction of the coronary vessels resulting from oxygen is secondary to the reduction in myocardial oxygen consumption. The regional myocardium in 12 mongrel dogs was perfused with femoral arterial blood at a constant rate of flow. While maintaining myocardial oxygen consumption equal by adjusting heart rate, coronary vascular resistance was compared under the two following conditions: 1) perfusion of the coronary artery with the dog's own femoral arterial blood (pO2 : 95 +/- 14 mmHg) and 2) perfusion with blood with a high level of oxygen tension (pO2 : 497 +/- 56 mmHg). Coronary vascular resistance was increased (p < 0.001) from 3.00 +/- 1.25 to 3.36 +/- 1.28 mmHg/ml/min by incresing the pO2 in the perfusing blood, even though myocardial oxygen consumption was kept at the same level. This increase in coronary vascular resistance resulting from the increase in oxygen tension was independent of the coronary perfusion rate as well as independent of the presence or absence of myocardial ischemia. This suggests that coronary vasoconstriction due to oxygen is not secondary to decreases in myocardial oxygen demand.

Animals↗
PubMed1979

Normal cardiac output in relation to age and body size.

The resting cardiac output was measured in 151 healthy persons (109 males and 42 females) of 4 to 78 years of age by the earpiece dye-dilution method by using an automatic calibration device of dye concentration. Cardiac index had a significantly inverse correlation to age in 105 cases with the age higher than 20 years: r=-0.491 and y=-4.874-0.023x, where y is cardiac index (liters/min/m2) and x is age (years). Stroke index also decreased linearly by aging throughout all ages: r=-0.426 and y=71.0-0.26 x, where x is stroke index (ml/m2) and x is age. There is no significant difference between males and females. A significant difference was found between the young group below 14 years of age and the other group older than 15 years when cardiac output was correlated to body sizes such as height, weight and surface area. The former which is corresponding to the growth age showed significantly higher cardiac output than the latter. From these results, age-matched normal predicted values were presented. It is suggested that the measured cardiac index and stroke index should be taken as abnormal if those values deviate from the normal value by 30% or more.

Adolescent↗
PubMed1977

Elevated coronary venous oxygen content during oxygen breathing in the ischemic myocardium under pacing-induced stress in dogs.

The purpose of the present study was to investigate the effect of oxygen inhalation on the stressed (pacing-induced) ischemic myocardium. In 13 open-chest dogs, the left anterior descending coronary artery was partially occluded, the coronary vein accompanying the artery was cannulated for coronary venous blood sampling and a myocardial strain gauge arch was sutured on the myocardium perfused with the partially occluded coronary artery in order to measure the myocardial contractile force. The heart rate was increased by left atrial pacing to increase myocardial oxygen consumption. Respiration was instituted either with oxygen or with room air. Increase of the heart rate caused an increase of blood flow through the partially occluded coronary artery, an increase of the local myocardial oxygen consumption and no consistent change of the local myocardial contractile force both during air breathing and oxygen breathing, provided that the heart rate was less than 200. These values decreased if the heart rate was increased more than 200 both during air and oxygen breathings. Coronary venous oxygen content from the local coronary vein accompanying the partially occluded coronary artery was 2.7 ml per 100 ml on the average during air breathing, while it was elevated to 3.8 ml per 100 ml during oxygen breathing. Although, pacing caused a similar change on coronary blood flow or myocardial contractile force both during air and oxygen breathings, elevated coronary venous oxygen content during oxygen breathing might indicate that ischemic myocardium becomes more aerobic during oxygen breathing. This may be one of the reasons why patient with coronary artery disease can perform more work without complaining chest pain during oxygen breathing.

Animals↗
PubMed1977

Measurement of cardiac output by earpiece dye-dilution method with automatic calibration of dye concentration.

A non-invasive method for measuring cardiac output by an earpiece dye densitometer was proposed. The densitometer is dichromatic and has an air capsule to make subject's ear bloodless by inflation, so that it can calibrate indocyanine green dye concentration without blood sampling. Duplicate measurements of cardiac output showed a good agreement in 40 cases (r = 0.97, standard deviation (S.D.) = 8.9%), which was comparable to the result of the cuvette method (r = 0.98, S.D. = 8.1%). Simultaneous measurements of cardiac output by the earpiece method (x) and the standard cuvette method (y) revealed a good agreement (r = 0.91, y = 0.96x+0.34, S.D. = 16.4%) in 52 measurements of 25 cases. A similarly good correlation was obtained between the two methods during ergometer exercise in supine position in 5 cases. These suggest that this earpiece dye-dilution method is reliable for cardiac output measurement and advantageous for clinical use because of non-invasive technique.

Adult↗
PubMed1976

Coronary blood flow and lactate metabolism during isometric handgrip exercise in heart disease.

Twenty-one patients with various heart diseases undergoing the coronary sinus catheterization had myocardial blood flow studies before and during isometric handgrip exercise. At 30% of the maximal voluntary contraction (MVC), handgrip increased both coronary sinus blood flow by 19.8% and myocardial O2 consumption by 21.0% on the average as compared to those at rest. At 20% of MVC, the increase of the both was slight except for 1 case. The increase in coronary sinus blood flow significantly correlated to the increase of myocardial O2 consumption. Lactate extraction ratio decreased to less than 10% during handgrip in 4 of 19 cases studied despite of normal values at rest. Lactate extraction ratio had significantly positive correlations with coronary sinus blood flow and myocardial O2 consumption during handgrip, while there were not significant ones at rest. It is suggested that isometric handgrip exercise is useful as a stress test for detection of myocardial ischemia in the heart of coronary artery disease.

Adolescent↗
PubMed1976

Regional difference of respiratory changes in pleural pressure between left and right thoraxes in dogs.

Respiratory changes in pleural pressure were recorded simultaneously from the left and right pleural spaces in 6 anesthetized closed-chest dogs in the supine, prone, left lateral and right lateral positions. Saline-filled radiopaque catheters connected to strain-gauge manometers were inserted percutaneously in the left and right pleural spaces by an air tight technique and their tips were placed in the mid-thoracic plane. The esophageal pressure was also recorded with the saline-filled system. The value of respiratory pressure amplitude (deltap, the difference between end-expiratory and minimal inspiratory pressures) in the pleural spaces was significantly greater in the left thorax than in the right in the supine, prone and right lateral positions. In 4 body positions, deltap in pleural pressure was significantly greater than in esophageal pressure. It is concluded that respiratory variations in pleural pressure of the left and right thorax are not the same and that postural change does not produce significant regional difference of the respiratory variations.

Animals↗
PubMed1976

Reduction of myocardial reactive hyperemia during oxygen breathing in dogs.

In 7 open-chest anesthetized mongrel dogs the left anterior descending coronary artery was occluded for 20 sec. Myocardial reactive hyperemia was recorded during air and oxygen breathings. The excess blood flow during the reactive hyperemia was smaller and the duration of the reactive hyperemia was shorter during oxygen breathing than during air breathing. It is suggested that the reduction of oxygen demand during oxygen breathing is a possible reason for the decreased reactive hyperemia and oxygen administration is beneficial in relieving myocardial ischemia.

Animals↗
PubMed1975

A method for quantitative detection of tricuspid regurgitation with double injection--single sampling dye-dilution technique.

A method for quantitative detection of tricuspid regurgitation is proposed. In cases without tricuspid insufficiency or intracardiac shunt, 1/slope (ts-fv) of the earpiece dye-dilution curve after injection of dye into the femoreal vein (fv curve) was significantly correlated with that (ts-pa) of the curve after injection into the pulmonary artery (PA curve) within each range of right heart blood volume (rbv) calculated as a product of cardiac output and mean transit time difference between FV curve and PA curve. The relationship among the 3 parameters was expressed as a statistically significant regression equation; log (tsfv) equals 0.9858 log (ts-pa) plus 0.2980 log (RBV) minus 0.6418 (p small than 0.005, sd of predicted ts-fv equals plus or minus 0.591). The assumption was made that tricuspid regurgitation caused prolongation ot ts-fv without any changes in ts-pa or RBV, being based on the concepts of the indicator dispersion and of the path-length distribution. The ratio of tricuspid regurgitation to cardiac output was calculated from (observed ts-fv-predicted ts-fv)/predicted ts-fv, in which predicted ts-fv is the value calculated from ts-pa and RBV using the equation shown above. In 2 patients who manifested clinical tricuspid insufficiency, large amount of tricuspid regurgitant fraction was determined by this method. It is suggested that the present method utilizing double injections--single sampling dye-dilution technique is useful for clinical quantitation of tricuspid regurgitation.

Adolescent↗