Biomedical subjects

A Koike

Publications and source records attributed to A Koike.

At least 73 records · Page 4Linked to original sources

PubMed1994

Determination of the anaerobic threshold by gas exchange: biochemical considerations, methodology and physiological effects.

This paper explains the physiological and biochemical basis of the anaerobic threshold (AT), achieved during physical exercise. The lactate concentration is approximately the same at rest in relatively fit adults, in normal sedentary subjects in adult patients with heart disease. But during exercise, the increase of lactate is inversely related to the physical fitness of the individual. During incremental work, the lactate concentration increases initially very little until a distinct metabolic rate (VO2 AT) is reached at which lactate starts to increase steeply (anaerobic threshold/AT; VO2 AT). Above the anaerobic threshold, accelerated glycolysis increases muscle lactic acidosis. This acidosis is buffered primarily by bicarbonate. The bicarbonate-derived CO2 causes an increased alveolar CO2 output relative to O2 uptake. Oxygen uptake is increased virtually linearly with work rate in healthy subjects with a slope of approximately 10 ml O2/min/Watt. VCO2 starts to increase more steeply in the mid-work-rate range after an initial linear behavior. This steepening is caused by an increased CO2 production from the HCO3-buffering of lactic acid for the range of work rates above the AT. Below the AT, the slope of increase in VCO2 is 1 or slightly less, averaging 0.95. Above the AT, it is greater than 1. The submaximal exercise protocol for the determination of AT includes a period of 2-3 min of unloaded cycling, a ramp program with x Watt increase/minute and a recovery period of 2 min. X is the rate of work rate increase per min, so that the incremental period of the exercise test lasts 8-10 min, stressing the patient for only a short time. The anaerobic threshold can be determined during the ramp program using the following four parameters: 1) steeper increase of VCO2 as compared to VO2 (V-slope-method); 2) respiratory exchange ratio = 0.95; 3) PETO2 increase; 4) VE/VO2 increase. The V-slope-method can be successfully applied, not only in healthy volunteers, but also in patients suffering from cardiac and/or pulmonary (breathing abnormalities) diseases. The so far published data show that the anaerobic threshold in healthy people and patients is a highly reproducible, accurately measurable, securely achievable parameter for the non-invasive evaluation of the individual cardiopulmonary exercise capacity.

Acid-Base Equilibrium↗

PubMed1994

[Antitumor effect of UFT against differentiated thyroid cancer].

We have determined the levels of 5-FU, tegafur and uracil in the thyroid cancer and normal thyroid tissue in the patients with differentiated carcinoma who were administered UFT 600 mg/day p.o. preoperatively for six days. 5-FU and uracil levels in the thyroid cancer tissue were significantly higher than in normal thyroid tissue. However, tegafur level did not show significant differences in any tissues. Two cases with differentiated carcinoma, which resulted in PR after prolonged administration of UFT were presented. These findings suggest that oral administration of UFT for a long term is a useful treatment for advanced differentiated thyroid cancer.

Adenocarcinoma, Follicular↗

PubMed1994

[Comparative trial of granisetron versus granisetron plus methylprednisolone for the prevention of nausea and vomiting induced by cancer chemotherapy].

Preclinical and clinical studies have demonstrated the effectiveness of granisetron in preventing emesis induced by antineoplastic chemotherapy. This comparative study was undertaken to investigate the efficacy and safety of granisetron (40 micrograms/kg) and granisetron plus methylprednisolone (MPL; 10 mg/kg). Sixty-eight patients were given granisetron 170 times and thirty-nine patients were given a combination of granisetron and MPL 81 times. Sixty-one patients received the treatment in crossover fashion during the same chemotherapy regimens. The emetic and nausea episodes were counted during the 24 hours following each chemotherapy treatment. Complete response, no emesis or less than two episodes, were obtained in 75.3% (128/170 times) of patients receiving granisetron alone compared to 85.2% (69/81 times) of patients receiving the combination of granisetron plus MPL. There were no significant differences in complete responses between the two groups, male and female, and each age group. However, 11 of eighteen patients receiving granisetron alone who responded mildly, if at all, with respect to nausea and vomiting, showed a complete or major response when MPL was added to granisetron. There were two patients who developed temporal paresthesia of the both hands as an adverse effect, but there was spontaneous recovery after 3 hours. Our data suggested that granisetron plus MPL was slightly more effective than granisetron alone and a safe antiemetic drug.

Adolescent↗

PubMed1993

Dynamic light scattering of aqueous solutions of linear aggregates induced by thermal denaturation of ovalbumin.

Dynamic light scattering measurements were performed on dilute aqueous solutions of native ovalbumin (OA) and on those of linear OA aggregates induced by thermal denaturation at low ionic strength and neutral pH. The weight-average molecular weight MW of four aggregates tested ranged from 1,700,000 to 5,500,000. The translational diffusion coefficient D0 of native OA at infinite dilution was estimated as 8.70 x 10(-7) cm2/s, which gave 56.0 A as the diameter of the rigid spherical particle. The intensity autocorrelation function of linear OA polymers was analyzed with the cumulant method to obtain the first cumulant gamma e. The dependence of gamma e on the scattering vector q at very low polymer concentration was found intermediate between those of a flexible chain and a rigid rod. The translational diffusion coefficient Dtr [identical to (gamma e/q2)q-->0] was in proportion to M-0.55W, and the magnitude was in good agreement with a value calculated from the wormlike cylinder model with values of three parameters determined in an earlier study, ML = 1600 A-1, d = 120 A, and Q = 230 A, where ML, d, and Q are the molecular weight per unit length, diameter, and persistence length, respectively. Based on these results, a new model, to be called as the dimer model, was proposed to interpret the formation mechanism of linear OA polymers induced by thermal denaturation.

Animals↗

PubMed1993

The trans-sphincteric and trans-sacral approaches for the surgical excision of rectal and presacral lesions.

In the decade from 1981 to 1990, 30 patients underwent a posterior transsacral approach at the Aichi Medical University Hospital for their benign or malignant rectal lesions. The operation was classified into two procedures, consisting of the transsphincteric approach and transsacral approach, in order to cope with the condition of the anal sphincter muscles; whether they were divided or not. Eleven rectal tumors were successfully excised through the opened-up rectum by using the transsphincteric approach, and excellent results were obtained without any postoperative complications. Using the transsacral approach, 2 presacral dermoid cysts and 11 rectal lesions were easily removed under direct vision. Their prognoses were excellent. The transsacral approach was also applied for the resection of recurrent rectal cancers after a radical, abdominoperineal resection in 6 patients suffering from intolerable local symptoms. All the patients were free from these uncomfortable local symptoms after the surgery. The posterior transsacral operation is thus considered to be of value not only for resecting benign rectal and presacral lesions, but also for resecting malignant rectal tumors in frail subjects who are unfit for radical operation and/or recurrent rectal cancer.

Adenoma, Villous↗

PubMed1993

Short-term effects of denopamine on anaerobic threshold and related parameters in patients with chronic heart failure: a double-blind crossover study.

BACKGROUND: The short-term effects of denopamine, an orally available beta-stimulant, on exercise capacity were studied in patients with chronic heart failure. METHODS AND RESULTS: Nineteen patients entered the study. Three patients had ischemic heart disease, 13 had dilated cardiomyopathy, and three had valvular disease; 16 patients were in New York Heart Association class II, and three patients were in New York Heart Association class III. Symptom-limited exercise testing (ramp protocol) on a bicycle ergometer with gas exchange analysis was conducted 1 hour after oral administration of either 20 mg denopamine or placebo. Drug administration sequence was randomly assigned in a double-blind crossover method, with 1 week between drugs. Peak VO2 was 20.4 +/- 3.2 and 21.2 +/- 3.1 ml/min/kg, respectively, for those administered the placebo and the drug, and anaerobic threshold was 13.1 +/- 2.1 and 14.0 +/- 2.0 ml/min/kg. There was a significant increase in peak VO2 (p < 0.05) and anaerobic threshold (p < 0.01) with denopamine, whereas no significant change was observed in peak work rate or exercise time. Denopamine increased heart rate in patients with atrial fibrillation but had little effect on heart rate in patients with sinus rhythm. CONCLUSION: Data obtained from gas exchange analysis are more sensitive and potentially more useful in the detection of short-term changes in exercise capacity than data obtained from either exercise time or peak work rate, indexes that are commonly used to assess drug therapy. Patients with mild-to-moderate heart failure with sinus rhythm, but not those with atrial fibrillation because of its frequent induction of tachycardia, may be good candidates for denopamine therapy.

Adrenergic beta-Agonists↗

PubMed1993

Role of platelet activating factor in ischaemia-reperfusion injury of isolated rabbit hearts: protective effect of a specific platelet activating factor antagonist, TCV-309.

OBJECTIVES: The aims were to confirm that platelet activating factor is released during reperfusion after global ischaemia in isolated blood perfused rabbit hearts, and to examine the protective action of TCV-309, a platelet activating factor antagonist, against reperfusion injury of cardiac muscle. METHODS: The hearts were mounted on a Langendorff apparatus and perfused with diluted blood perfusate. After cardiac arrest with St Thomas's cardioplegic solution, the hearts were subjected to global ischaemia for 120 minutes at 25 degrees C, and then reperfused for 60 minutes at 37 degrees C. Release of platelet activating factor into the coronary effluent was quantified by radioimmunoassay. The effect of TCV-309 on left ventricular function and release of creatine kinase was measured. RESULTS: A pronounced release of platelet activating factor occurred after the commencement of reperfusion, although it was not detectable before induction of ischaemia. Release of platelet activating factor occurred over 60 minutes of the reperfusion period. In the control, left ventricular developed pressure after 60 minutes of reperfusion recovered to 54.3(SEM 1.7)% (n = 5) of the preischaemic value. In the hearts treated with TCV-309 at concentrations above 0.3 microM, recovery of left ventricular developed pressure was significantly improved (77.6(2.0)% at 1 microM, p < 0.01 v control). Leakage of creatine kinase during the initial five minutes of reperfusion was significantly less in the hearts treated with 1 microM TCV-309 than in the controls (5.2(0.4) v 12.2(1.4) IU.g-1 wet weight, p < 0.01). CONCLUSIONS: Release of platelet activating factor occurred during the reperfusion period in Langendorff perfused hearts. Treatment with the platelet activating factor antagonist TCV-309 significantly improved postischaemic left ventricular function and decreased creatine kinase release. These results suggest that platelet activating factor is involved in myocardial injury during ischaemia-reperfusion.

Animals↗

PubMed1993

Eisenin (L-pyroGlu-L-Gln-L-Ala), a new biological response modifier.

Eisenin (L-pyroGlu-L-Gln-L-Ala), a tripeptide extracted from a brown marine alga (Eisenia bicyclis Setchell) showed the immunological activity to augment natural cytotoxicity of peripheral blood lymphocytes (PBLs) in humans. This activity could be seen when it was added directly to 51Cr release assay, and also when PBLs alone were incubated with this compound for 0.5-1 h before addition to the 51Cr release assay. The resulting augmented cytotoxicity can be attributed to natural killer cells because treatment of eisenin-stimulated PBLs with anti-Leu 11b monoclonal antibody (mAb) plus complement completely abolished the augmented cytotoxicity, and, moreover, deletion of Leu 19-positive cells with anti-Leu 19 mAb (mouse IgG1) and anti-mouse IgG-coated magnetic beads showed the same effect. Eisenin could not augment natural cytotoxicity of Sephadex G-10 column-eluted cells. Eisenin rendered K-562 target cells resistant to lysis by PBLs stimulated by eisenin. Both amino acids, L-pyroglutamic acid and L-alanine, as well as a mixture of the three component amino acids of eisenin could augment the natural cytotoxicity. Therefore, it is considered that the structure responsible for the augmentation of natural cytotoxicity by eisenin may be that of the amino acids.

Alanine↗

PubMed1993

Insulin-like growth factor-I induces hypertrophy with enhanced expression of muscle specific genes in cultured rat cardiomyocytes.

BACKGROUND: Cardiac hypertrophy is commonly observed in acromegalic patients, in whom serum insulin-like growth factor-I (IGF-I) levels are elevated. In the present study, we examined whether IGF-I induces hypertrophy in cultured neonatal rat cardiomyocytes through its specific receptor and whether IGF binding protein-3 (IGFBP-3), which is a major circulating carrier protein for IGF-I, inhibits IGF-I-induced cardiac hypertrophy in vitro. METHODS AND RESULTS: Because the response of cardiac hypertrophy is characterized by the induction of expression for muscle-specific genes, the effect of IGF-I on steady-state levels of mRNA for myosin light chain-2 (MLC-2) and troponin I and for skeletal and cardiac alpha-actin isoforms was evaluated by Northern blot analysis. IGF-I (10(-7) M) increased mRNA levels for MLC-2 and troponin I as early as 60 minutes with maximum levels by 6 hours, which were maintained for as long as 24 hours. IGF-I (10(-7) M) also increased transcripts for skeletal alpha-actin but not for cardiac alpha-actin. The cell size as evaluated morphometrically was almost doubled after 48-hour treatment with IGF-I. IGF-I induction of protein synthesis was dose dependent (10(-10) to 10(-7) M) with a maximal 2.2-fold increase seen at 10(-8) M. In contrast to the hypertrophic effect of IGF-I, growth hormone affected neither protein synthesis nor expression for muscle-specific genes. Binding study using 125I-IGF-I revealed the presence of specific binding sites for IGF-I in rat cardiomyocytes. IGFBP-3 induced a dose-dependent inhibition of protein synthesis stimulated by IGF-I; IGFBP-3 (10(-7) M) completely inhibited the [3H]leucine uptake stimulated by IGF-I (10(-8) M). IGFBP-3 similarly inhibited the IGF-I-stimulated gene expressions for MLC-2 and troponin I. CONCLUSIONS: These results suggest that IGF-I directly causes cardiac hypertrophy and that its effect can be blocked by IGFBP-3.

Actins↗

PubMed1993

Respiratory control during exercise in patients with cardiovascular disease.

The pathophysiologic mechanism for exertional dyspnea, the main symptom of patients with heart failure, has not been fully clarified. To determine the relationship between exercise hyperpnea and the lactic acidosis in patients with heart failure, we evaluated ventilation during incremental exercise both below and above the lactic acidosis threshold in 16 normal subjects and in 48 patients with cardiovascular disease while expired gas was analyzed continuously. The peak oxygen uptake and oxygen uptake at the lactic acidosis threshold decreased significantly as the New York Heart Association (NYHA) functional class severity increased. the slope of the increase in ventilation to the increase in oxygen uptake (delta VE/delta VO2) at work rates below the lactic acidosis threshold did not differ between normal subjects and patients with heart failure. Above the lactic acidosis threshold, however, the slope of delta VE/delta VO2, which was higher than that below the lactic acidosis threshold in each of four groups, was steeper in patients in NYHA Class II (60.8 +/- 17.9) and Class III (66.5 +/- 21.2) when compared with that in the normal subjects (46.6 +/- 13.5) or the patients in NYHA Class I (46.1 +/- 10.3). The lactic acidosis caused by decreased oxygen transport to working muscles accounts for the higher ventilation during exercise in cardiac patients. These data suggest that the increased ventilation during exercise, which must be related to exertional dyspnea, in patients with cardiovascular disease is primarily the consequence of a stimulus to regulate arterial pH.

Acidosis, Lactic↗

PubMed1993

Endothelin-1 is an autocrine/paracrine factor in the mechanism of angiotensin II-induced hypertrophy in cultured rat cardiomyocytes.

To elucidate the cellular mechanism by which angiotensin II (ANG II) induces cardiac hypertrophy, we investigated the possible autocrine/paracrine role of endogenous endothelin-1 (ET-1) in ANG II-induced hypertrophy of neonatal rat cardiomyocytes by use of synthetic ET-1 receptor antagonist and antisense oligonucleotides to preproET-1 (ppET-1) mRNA. Northern blot analysis and in situ hybridization revealed that ppET-1 mRNA was expressed in cardiomyocytes, but, to a lesser extent, in nonmyocytes as well. ANG II upregulated ppET-1 mRNA level by threefold over control level as early as 30 min, and it stimulated release of immunoreactive ET-1 from cardiomyocytes in a dose- and time-dependent manner. ET-1 stimulated ppET-1 mRNA levels after 30 min in a similar fashion as ANG II. Tetradecanoylphorbol-acetate (10(-7) M) mimicked the effects of ANG II and ET-1 on induction of ppET-1 mRNA. ANG II-induced ppET-1 gene expression was completely blocked by protein kinase C inhibitor H-7 or by down-regulation of endogenous protein kinase C by pretreatment with phorbol ester. ET-1 and ANG II stimulated twofold increase [3H]leucine incorporation into cardiomyocytes, whose effects were similarly and dose dependently inhibited by endothelin A receptor antagonist (BQ123). Introduction of antisense sequence against coding region of ppET-1 mRNA into cardiomyocytes resulted in complete blockade with ppET-1 mRNA levels and [3H]leucine incorporation stimulated by ANG II. These results suggest that endogenous ET-1 locally generated and secreted by cardiomyocytes may contribute to ANG II-induced cardiac hypertrophy via an autocrine/paracrine fashion.

Angiotensin II↗

PubMed1993

[Efficacy of the treatment of gastric cancer as neo-adjuvant chemotherapy of 48 hour continuous intravenous infusion of 5-fluorouracil (5-FU) with leucovorin (LV)].

A 51-year-old female with inoperable gastric cancer and with infiltration of pancreatic tail diagnosed by abdominal CT was treated with leucovorin (LV) and 5-fluorouracil (5-FU). The regimen was: LV 30 mg/body/24 hr prior to 5-FU 1,000 mg/m2/day for 48 hrs. This treatment was repeated 6 times. After treatment, the size of tumor decreased so that the patient was able to be operated (Total gastrectomy with partial distal pancreatico-splenectomy). During the treatment, patient showed no side effect except for slight nausea. This neo-adjuvant chemotherapy might be a recommendable treatment of advanced gastric cancer.

Adenocarcinoma↗

PubMed1993

[Efficacy of 48-hour infusion of 5-fluorouracil for gall bladder cancer].

Usefulness of an adjuvant chemotherapy for 23 patients who had undergone "non-curative" resection for adenocarcinomas of the gallbladder was investigated. Patients were divided into two groups: Group A (16 patients) was given MF (mitomycin C 6 mg/m2, 5-fluorouracil 250 mg/body) by injection on the 2nd and 9th postoperative day and received orally Tegafur 600 mg/day and PSK 3 g/day. Group B(7 patients) was treated weekly with a 48-hour infusion of 5-FU (1,000 mg/m2/24 hours), for 6 weeks and leucovorin (30 mg/body) was given for 2 hours prior to 5-FU infusion. The results were evaluated by the Kaplan-Meier method. Response rate of anti-tumor was 0% in Group A and 14.3% in Group B, including: PR, 1 and NC, 6 cases. The 50% survival time was 230 days in group A and 471 days in group B (p = 0.0008). The results suggest that treatment with 5-FU and LV is effective for gallbladder cancer.

Adenocarcinoma↗

PubMed1992

Purification and some properties of L-fucose dehydrogenase from Agrobacterium radiobacter and its application to the assay of bound-fucose in glycoconjugates.

L-Fucose dehydrogenase was found in the cell extract of Agrobacterium radiobacter and purified to homogeneity about 480-fold with 16% recovery. The molecular weight of the enzyme was approx. 64,000. The enzyme was active in the neutral pH range, unlike other L-fucose or D-arabinose dehydrogenases which are active only in the alkaline pH range. Using this enzyme and alpha-L-fucosidase F-I of Bacillus circulans (Tsuji, Y., Yamamoto, K., Tochikura, T., Seno, T., Ohkubo, Y. and Yamaguchi, H. (1990) J. Biochem. 107, 324-330) simultaneously, we developed a new coupled enzymatic method in a single buffer system for determining bound-fucose in biological materials. The fucose released by alpha-L-fucosidase F-I was oxidized with L-fucose dehydrogenase in the presence of NAD+, and the NADH formed was measured by absorbance of ultraviolet or utilized to generate color in a reaction involving CuSO4 and neocuproine. Using these methods, bound-fucose in various oligosaccharides and proteins such as lacto-N-fucopentaoses and porcine gastric mucin were quantitated within 15 min.

Animals↗

PubMed1992

Preoperative serum immunosuppressive acidic protein (IAP) test for the prognosis of gastric cancer: a statistical study of the threshold level and evaluation of the effect of the biological response modifier PSK.

The prognostic value of immunosuppressive acidic protein (IAP), which is known to suppress various immune responses in cancer patients, was studied in a prospective randomized trial of advanced gastric cancer patients, designed to evaluate the effect of PSK, a kind of biological response modifier with protein-bound polysaccharides. Preoperative serum IAP levels were determined in 228 patients who received radical gastric resection and tests conducted in one laboratory by the single radial immunodiffusion (SRID) method. All patients were followed up for 24 months or more. There was an overall significant difference in disease-free survival time in favour of the PSK-treated group compared with the control group. Preoperative IAP values were strongly associated with disease-free survival time. The statistical analysis to define an appropriate cut-off level for IAP was performed using Cox's proportional hazards model. The most significant difference was observed at the threshold value of 580 micrograms/ml, the hazard ratio being 2.13 with a 95% confidence interval [1.17, 3.88] (P = 0.013). Patients in the PSK-treated group with a preoperative IAP of lower than 580 micrograms/ml showed improved disease-free survival (P = 0.029), however, no significant difference was seen between the two groups when the preoperative IAP exceeded the threshold level. From these results, 580 micrograms/ml is postulated to be the most appropriate threshold value for predicting the prognosis of advanced gastric cancer patients, and it is suggested that PSK would be most effective in patients whose preoperative IAP level is lower than the threshold level.

Biomarkers, Tumor↗

PubMed1992

Anaerobic metabolism as an indicator of aerobic function during exercise in cardiac patients.

To determine whether patients with heart disease depend more than normal subjects on anaerobic metabolism to perform the same level of exercise, the anaerobic threshold, slope of the increase in carbon dioxide output with respect to oxygen uptake (delta VCO2/delta VO2) and the slope of the increase in oxygen uptake with respect to the increase in work rate (delta VO2/delta WR) both below and above the anaerobic threshold during exercise were evaluated. A total of 106 patients with chronic heart disease and 42 healthy subjects performed a symptom-limited incremental exercise test in a ramp pattern on a cycle ergometer. Peak oxygen uptake was significantly lower in the patients with heart disease than in the normal subjects. The anaerobic threshold, which was 20 +/- 4.6 ml/min per kg in normal subjects, decreased significantly with progressing severity of functional class: 16 +/- 2.4, 14.1 +/- 2.5 and 11.3 +/- 1.5 ml/min per kg, respectively, in patients in class I, class II and class III. The slope of delta VO2/delta WR, which represents the degree of aerobic metabolism, was also decreased both below and above the anaerobic threshold with increasing severity of heart disease. delta VCO2/delta VO2 below the anaerobic threshold was approximately 0.9 (p = NS between normal subjects and patients). However, delta VCO2/delta VO2 above the anaerobic threshold became steeper with increasing severity of heart disease: 1.37 +/- 0.17 in normal subjects versus 1.55 +/- 0.24, 1.67 +/- 0.3 and 1.8 +/- 0.35 respectively, in patients in functional class I, class II and class III.(ABSTRACT TRUNCATED AT 250 WORDS)

Aerobiosis↗

PubMed1992

Hemodynamic effects and pharmacokinetics of long-term therapy with ibopamine in patients with chronic heart failure.

To evaluate the attenuation of the effectiveness of long-term ibopamine therapy, ibopamine was administered in single doses of 100 and 200 mg to 10 patients with chronic heart disease. The hemodynamic studies using Swan-Ganz catheter and pharmacokinetic studies were carried out. Ibopamine was found to increase cardiac output and stroke index and to decrease systemic vascular resistance in this acute study. Six patients underwent long-term therapy with the drug and were evaluated for the development of tolerance. Three out of 5 patients experienced an improvement in NYHA functional class after 12-23 weeks of treatment. There was no attenuation in the effects of ibopamine on hemodynamics, pharmacokinetic parameters remained almost unchanged, and tolerance was not observed. These results suggest that ibopamine is useful as an orally administered anti-heart failure drug.

Administration, Oral↗

PubMed1992

Cardiac output-O2 uptake relation during incremental exercise in patients with previous myocardial infarction.

BACKGROUND: The cardiac output-O2 uptake (VO2) relation, which is thought to be linear and predictable in normal humans, has not been clarified in cardiac patients. We evaluated the relation between cardiac output and VO2 during the incremental exercise test in patients with previous myocardial infarction. METHODS AND RESULTS: Twenty-two patients (age, 58.1 +/- 8.0 years) with previous myocardial infarction performed a symptom-limited exercise test on a cycle ergometer. VO2 was calculated from the expired gas analysis, and cardiac output was measured by a computerized cadmium telluride detector every 10 seconds during exercise. The ratio of increase in VO2 to the increase in work rate (delta VO2/delta WR) below and above the anaerobic threshold (AT) was 11.1 +/- 3.6 and 11.1 +/- 2.9 ml/min/W, respectively, showing no significant difference. However, the ratio of increase in cardiac output to increase in work rate (delta CO/delta WR) below the AT was 50.1 +/- 26.6 ml/min/W and was significantly decreased to 11.8 +/- 25.3 ml/min/W above the AT (p = 0.0002). The decreased delta CO/delta WR above the AT primarily would be due to silent myocardial ischemia produced by exercise, as there was the presence of 201Tl redistribution in 15 of 16 patients in whom myocardial 201Tl scintigraphy with dipyridamole or exercise stress testing was evaluated. delta CO/delta VO2, which has been reported to be approximately 5.5 in normal subjects, was only 4.4 +/- 2.6 at work rates below the AT and was decreased to 1.1 +/- 2.3 at work rates above the AT. CONCLUSIONS: The relation between cardiac output and VO2 during exercise in patients with previous myocardial infarction differs profoundly from that reported in normal subjects. These findings must be considered when we noninvasively estimate the change in cardiac output during exercise by obtaining VO2 in patients with coronary artery disease.

Adult↗