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Biomedical subjects

D Saito

Publications and source records attributed to D Saito.

At least 109 records · Page 6Linked to original sources
PubMed1990

[Studies on faint attack due to arrhythmias with Holter electrocardiogram].

Out of 1,400 Holter ECGs, 15 records revealed arrhythmias which would be responsible for faint attack, including 8 sick sinus syndrome with cardiac arrest, 4 non-sustained ventricular tachycardia (VT), 2 paroxysmal atrial fibrillation and 1 paroxysmal supraventricular tachycardia. All of cardiac arrest corresponding to faint attack lasted for longer than 4 sec, and an averaged duration of the arrest was 5.8 +/- 2.3 sec. This was significantly longer than that with no subjective symptoms, 3.4 +/- 0.7 sec. Duration and rate of VT did not show any significant relationship with faint attack. The result suggests that cardiac arrest is mostly responsible for arrhythmia-induced involvement of cerebral circulation and faint attack. It is also suggested that cardiac arrest longer than 4 sec should be extensively treated including pacemaker implantation.

Arrhythmias, Cardiac↗
PubMed1989

Reperfusion through balloon catheter to minimize myocardial infarction during the interval between failed percutaneous transluminal coronary angioplasty and emergency coronary artery bypass grafting.

A 65-year-old man was admitted with chest pain. A diagnosis of spastic angina was made because of symptoms of recurrent anginal attacks associated with ST-segment elevations in the electrocardiogram. A selective coronary arteriogram revealed a 90% diameter narrowing of the proximal left anterior descending coronary artery (LAD). No angiographically visible collaterals from the right coronary artery to the LAD were observed. The ventriculogram showed normal contraction of the left ventricle with an ejection fraction of 65%. Percutaneous transluminal coronary angioplasty (PTCA) failed resulting in total occlusion of the stenosis. Repeat PTCA at a higher pressure and of longer duration failed to redilate the artery. Reperfusion with the blood from the femoral artery through the balloon catheter, which was used for the PTCA, was carried out until coronary artery bypass grafting (CABG). Blood flow rate of perfusion was approximately 25 ml/min. Reperfusion through the balloon catheter reduced chest pain and ST-segment elevations in the electrocardiogram. The patient tolerated the operative procedure well and his post-operative course was uncomplicated. The interval between the acute occlusion and revascularization by CABG was approximately 4 1/4 h. The ventriculogram taken 56 days after the CABG demonstrated normal contraction of the anterior wall of the left ventricle with an ejection fraction of 63%. Abnormal Q waves did not appear in precordial leads of the electrocardiogram after the surgery. The thallium scintigram showed no perfusion defects. In conclusion, this case suggested that autologous blood reperfusion through balloon catheter would be worth attempting in some cases for minimization of myocardial infarction during the interval between failed PTCA and emergency CABG.

Angioplasty, Balloon, Coronary↗
PubMed1989

Forskolin potentiates myocardial reactive hyperaemia in the open chest dog: the contribution of adenylate cyclase.

Forskolin, a diterpene, directly stimulates adenylate cyclase and also potentiates receptor mediated stimulation of this enzyme by many stimulatory agonists. We exploited the potentiating effect of forskolin to test the hypothesis that activation of adenylate cyclase contributes to myocardial reactive hyperaemia, especially by release of adenosine at the time of brief coronary occlusions. In 10 open chest dogs, intracoronary forskolin infusions which produced plasma concentrations between 0.22 and 0.34 mumol.litre-1 slightly increased coronary blood flow and had no effect on haemodynamics or myocardial metabolism. Under these conditions, though peak reactive hyperaemic flow rates were not affected, forskolin infusions reversibly potentiated repayments of flow debt by 28, 25 and 27% following coronary occlusions of 15 s, 20 s and 30 s, respectively (p less than 0.05). In another seven dogs, after observations of the effects of forskolin (0.16-0.26 mumol), 10 mumol of 8-phenyltheophylline, a potent adenosine antagonist, was infused simultaneously with forskolin into the coronary arteries. Forskolin increased debt repayments by about 23-27% following 15 s, 20 s and 30 s occlusions, but with simultaneous 8-phenyltheophylline, forskolin induced increments in the debt repayments were reduced significantly (p less than 0.05). These results indicate that adenylate cyclase contributes to myocardial reactive hyperaemia, and adenosine has a significant role as metabolic regulator of reactive hyperaemia through activation of adenylate cyclase.

Adenosine↗
PubMed1989

Coronary flow reserve and oxygen metabolism of the right ventricle.

The flow reserve of the right coronary artery (RCA) and myocardial oxygen extraction are important tractors in any investigation of the mechanisms of impaired right ventricular function. The present study induced brief coronary occlusions and examined the effect on right coronary blood flow in normal dogs, and the effect on myocardial oxygen metabolism in dogs with right ventricular hypertrophy (RVH). Right coronary flow reserve, represented by occlusion duration causing a half maximum dilatation (T1/2), was greater in the RCA than in the left anterior descending coronary artery of normal dogs; 11.4 +/- 2.3 sec vs 5.9 +/- 1.4 sec. Myocardial oxygen extraction ratio (EO2) of the right ventricle (RV), 51.3 +/- 1.6%, was significantly (p less than 0.05) lower than the index of the left ventricle (LV), 60.6 +/- 1.0%, and the extraction of the RV increased significantly in association with an increase of myocardial oxygen demand. In dogs with RVH caused by chronic banding of the pulmonary artery, this dominant oxygen reserve was lost: the EO2 of the hypertrophied RV was high compared with the EO2 of the normal RV (57.3 +/- 3.4% vs 51.3 +/- 1.6%, p less than 0.05), and no further increase in EO2 was observed in the hypertrophied RV in response to the elevation of the myocardial oxygen requirement. Oxygen usage per 100g of the RV for a certain level of overall RV work, rate-pressure product, was significantly (p less than 0.02) lower in the hypertrophied RV (0.00054 mlO2/beat.mmHg) than in the normal RV (0.0012 mlO2/beat.mmHg).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Factors influencing acute high-grade restenosis in emergency percutaneous transluminal coronary angioplasty for acute myocardial infarction.

We studied the factors which may induce acute high grade restenosis in emergency percutaneous transluminal coronary angioplasty (PTCA). PTCA was attempted in 50 patients with acute myocardial infarction, and the balloon catheter passed successfully across the occlusion site in 47 (94%) of the patients. These 47 patients were analyzed. "Acute restenosis" was defined as a lesion which was revascularized to less than 50% luminal reduction narrowed again to more than 75% luminal reduction 5 min after the balloon inflation. Univariate and multivariate analyses were used for determining factors which significantly influenced acute restenosis. The incidence of at least one restenosis episode was 45%. Multiple regression analysis selected 5 factors associated significantly with an increased rate of acute restenosis: 1) angiographic evidence of dissection, 2) lesion in the right coronary artery (RCA), 3) lack of or insufficient administration of thrombolytic agent preceding PTCA, 4) curved lesion and 5) relatively small balloon/artery diameter ratio. Acute restenosis correlated significantly with late reocclusion. This study indicates that it is important to administer a thrombolytic agent prior to emergency PTCA, and to use an adequately sized balloon to the artery when the acute restenosis occurs by using relatively smaller sized balloon. The present data also demonstrated that patients with RCA and a curved lesion have a relatively high risk of acute restenosis. This study indicates how patients with relatively high risk of acute restenosis may be identified.

Acute Disease↗
PubMed1989

Improvement of reduced coronary vasodilatory response during reactive hyperemia by diltiazem.

This study was performed to reconfirm transiently-reduced vasodilatory responses of the coronary artery in the reactive hyperemic period, and also to study whether an increase in calcium influx into the coronary smooth muscle accounts for the reduced coronary vasodilatory responses. Blood flow in the circumflex coronary artery was measured with an electromagnetic flow transducer in anesthetized open-chest dogs. Two successive occlusions for 3 to 7 s performed in pairs with a brief interval were accompanied by decreasing reactive hyperemia: the maximum reduction of reactive hyperemia appeared when the occlusion period was around 5 s with a 5-s interval. Around 5 s after the release of occlusion, excess arterial inflow almost equaled the blood flow debt incurred during the first occlusion. Pretreatment with diltiazem (150 micrograms/kg), a calcium entry blocker, significantly attenuated the reduction of coronary vasodilatory responses, but glyceryl trinitrate (nitroglycerin) did not affect the phenomenon of coronary reactivity. The results suggest that excess accumulation of calcium in the smooth muscle of small coronary arteries occurred during an early period of post-occlusion hyperemia, which resulted in a reduced vasodilatory reactivity of the vessels to the second ischemic stimulus.

Animals↗
PubMed1989

Exercise body surface mapping in patients with left ventricular hypertrophy: comparison with stress thallium scans (SPECT).

To evaluate exercise-induced myocardial ischemia in patients with electrocardiographic evidence of left ventricular hypertrophy (LVH), including ST.T changes, body surface maps (QRST area maps) were recorded using 87 lead points before and after exercise. The patterns of the subtraction QRST area maps (S-maps) were compared with the findings of stress thallium (T1) scans in 31 patients with hypertrophic cardiomyopathy and in five with essential hypertension. All 18 patients whose S-maps revealed changes less than -40 muVS or only an increase over the anterior chest region showed no positive findings on the stress T1 scans. However, there were clearly positive findings on stress T1 scans in eight (89%) of nine patients whose S-maps revealed changes greater than -40 muVS over a wide precordial region or in six (67%) of nine patients whose S-maps revealed increases over the anterior chest region and had accompanying changes greater than -40 muVS somewhere over the precordial region. These results suggested that exercise QRST area maps could differentiate exercise-induced myocardial ischemia from LVH with ST.T changes.

Aged↗
PubMed1989

[Study of local interstitial hyperthermia induced by low power Nd:YAG laser].

A comparative study of local interstitial hyperthermia induced by low power Nd:YAG laser (laser hyperthermia) and microwave hyperthermia was carried out in vivo and in vitro in an attempt to clarify the therapeutic effect and the mechanism. Both therapies, after seven days, caused marked amounts of coagulated necroses in the transplanted tumors of human pancreatic carcinoma. Immediately after those therapies, electron microscopic examination of the tumor tissues showed membranous, cytoplasmic, nuclear and mitochondrial damage; however, this damage was much more extensive in laser hyperthermia compared to microwave hyperthermia. The cytocidal effects of heating alone, laser hyperthermia and microwave hyperthermia were also studied in vitro. Of the three, laser hyperthermia demonstrated the most notable decrease in viability. Thus, in the mechanism of laser hyperthermia, it seems that the immediate effect is cellular damage caused by both heat energy and Nd:YAG laser light followed by subsequent damage of tumor vessels.

Animals↗
PubMed1989

[Effect of sodium thiosulfate on the antitumor effect and nephrotoxicity of CDDP in human gastric cancer transplanted in nude mice].

Sodium thiosulfate (STS) is known to decrease the nephrotoxicity of cisplatin (CDDP). CDDP has been recognized effective in some type of gastric cancers, and there has been an attempt to examine the optimal dose of STS, which suppresses the CDDP-induced nephrotoxicity without interfering its anticancer effect. The gastric cancer cell lines (KATO-III and MKN 45) were transplanted into BALB/c nu/nu mice. CDDP was injected intraperitoneally once a week 5 times with various doses of STS, and the effects of STS on the antitumor effect as well as the nephrotoxicity of CDDP were examined. The antitumor effect of CDDP (9 mg/kg) was suppressed by 30% with the simultaneous injection of 372 mg/kg (50 fold-molar radio of STS to CDDP) and abolished by 1,488 mg/kg (200 fold-molar radio) of STS. The elevated serum BUN and the kidney content of platinum following CDDP administration were at the normal ranges in the nude mice received these doses of STS. Also, the atrophic and regenerative changes of the kidney tubules induced by CDDP were scarcely observed in these nude mice. From these results, only 50 fold-molar radio of STS to CDDP suppresses the nephrotoxicity of CDDP without interfering its antitumor effect, and this rather smaller amounts of STS is considered to be optimal. Further studies, however, will be needed for clinical application.

Animals↗
PubMed1988

The QRS complex of the standard 12-lead electrocardiogram in septal myocardial infarction.

Interventricular septal involvement in myocardial infarction is suggested by the findings of a QS deflection in lead V1 and/or absence of the Q wave in leads I and V6, using the standard 12-lead electrocardiogram (ECG). However, these findings were not sufficiently established for the criteria of septal infarction, because several factors including anatomic position of the heart, changes of intraventricular conduction, and condition of the lung would affect the QRS complex in the leads. In this study, we analyzed the ECGs of anterior myocardial infarction with (group A) and without (group B) involvement of the first septal coronary artery. The R wave in V1 was absent in 64.7% of group A and 60.0% of group B. The Q wave was absent in 35.3% in lead I and 64.7% in lead V6 of group A, while in group B the Q wave in leads I and V6 were not observed in 60.0% and 40.0%, respectively. The prevalence rates of the R wave and the Q wave in these leads were not significantly different between the two groups. Left ventriculography revealed that the prevalence rate of the R wave in V1, and the Q wave in I and V6 was not significantly different, regardless of the presence or absence of impaired septal motion. Experimental study in anesthetized dogs confirmed the difficulty in clarifying acute septal ischemia by changes in the QRS complex. These results indicate that septal myocardial infarction is hardly detectable with changes in the QRS complex of the standard 12-lead electrocardiogram.

Coronary Vessels↗
PubMed1988

Effect of heart rate and myocardial contractile force on coronary resistance.

The effect of the heart rate and myocardial contractile force on the extravascular resistance to blood flow of the left anterior descending coronary artery (LAD) was evaluated in 15 mongrel dogs anesthetized with sodium pentobarbital. The LAD was maximally dilated by intracoronary infusion of adenosine, which precluded the influence of vasomotor tone. Increases in the heart rate and myocardial contractile force decreased coronary blood flow in the absence of a change in coronary perfusion pressure. The changes in mean coronary resistance showed a significant linear relationship to changes in developed tension. The changes in coronary resistance caused by varying the heart rate and contractile force were so small that a normal coronary vascular tree could easily compensate for the increase in resistance. However, it is supposed that with critical stenosis of the vascular tree even a small increase in resistance might cause deleterious effects on coronary blood flow.

Adenosine↗
PubMed1988

[Development of scirrhous cancer of the stomach; a speculation from clinical materials obtained].

In order to get information about the biological behavior of scirrhous gastric cancers in their growth, we examined 1) retrospective and 2) prospective follow-up cases of scirrhous cancer, 3) scirrhous cancers on the gastric remnant, 4) those misdiagnosed as early cancer and 5) similarity in sex ratio, location and histological type (backgrounds of growth) between early and advanced cancers by multivariate analysis. The results obtained were as follows: 1) In the five well documented cases of scirrhous cancer being available for retrospective study (see Table 1), superficial depressed lesions were seen previously. And four of the five were non-ulcerative (without converging folds) and the rest one was ulcerative. In these five cases intervals between elastic and contracted appearance (E-C interval) in their growth was very short. The shortest was only 40 days (see Fig. 1). 2) In contrast, in a case who had been followed up from localized advanced to scirrhous cancer prospectively, the term was relatively long, namely one year and half. 3) In eight cases who had recurred as scirrhous cancer on the gastric remnant and been resected, time intervals between the initial operation and recurrence detected were diverse, and there was no relationship between the time intervals and clinicopathological features of the primary lesion (Table 2). 4) Six cases of scirrhous cancer were misdiagnosed as early by radiology and/or endoscopy (Table 3). In these six, gastric wall was not contracted macroscopically in spite of the presence of diffuse scirrhous invasion histologically ("elastic scirrhous cancer"). 5) According to the multivariate analysis (Hayashi's quantification theory No. 3) examining the similarity in backgrounds of growth between 937 cases of early and 2065 of advanced cancers, non-ulcerative II c type of early cancers, particularly in younger generation showed close similarity to scirrhous cancers. The above results may suggest following consideration about development of scirrhous cancers: Most of the original lesions correspond to II c type of early cancers without converging folds (non-ulcerative) in younger generation (results 1 and 5). Growth patterns from the original to the final gross appearance are classified into two groups, slow (through locally advanced stage as result 2) and rapid (direct change from early lesion as result 1). Because E-C interval is very short in the rapid growing cases (result 1) and scirrhous cancer is not always contracted macroscopically (result 4), it is possible to consider the presence of some endogenous factors from cancer cells, which make "elastic scirrhous cancers" contracted rapidly and simultaneously.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenocarcinoma, Scirrhous↗
PubMed1988

Enhancement of coronary conductance by alpha-human atrial natriuretic polypeptide without effects on myocardial contractility.

The effect of synthetic human atrial 28-amino acid peptide (alpha-human atrial natriuretic polypeptide, alpha-hANP) on coronary circulation and cardiac functions was examined in open-chest dogs. Intravenous injection of alpha-hANP increased coronary and systemic conductance, and coronary and aortic blood flow with a significant fall in blood pressure. Continuous infusion of alpha-hANP into the left anterior descending coronary artery (LAD) increased LAD blood flow in a dose-dependent manner. The linear regression analysis revealed the relationship of logit (changes in mean coronary conductance (delta MCC] = 1.45 x log (coronary plasma concentration of alpha-hANP) + 7.51 (r = 0.87, n = 29). REC50 of alpha-hANP was 5.1 microM, where REC50 was the concentration to increase MCC to a half maximum MCC during reactive hyperemia after a 30-s coronary occlusion. alpha-hANP increased coronary conductance with no changes of myocardial oxygen consumption (MVO2) when blood pressure remained constant. Indices of myocardial contractility measured with a strain gauge arch, myocardial force (F), max dF/dt and LV max dp/dt, were not altered by either bolus intravenous injection or continuous intracoronary infusion of alpha-hANP. These results indicated a direct increase by alpha-hANP of coronary and systemic vascular conductance.

Animals↗
PubMed1988

[Continuous infusion of anti-cancer drug with balloon infusors].

We evaluated the safety and stability of balloon infusors in which the distended elastomotor balloon acts as the energy source. Continuous intravenous administration of 5-fluorouracil with the infusor was carried out in nine patients with advanced gastrointestinal cancers. In additional two patients, morphine hydrochloride was administered continuously in the vein or in the epidural space. The patients were carefully observed and hematological and biochemical examinations were performed. Infusion volume was calculated by measuring the weight of the infusor. The present study showed that this infusor was safe and easy to handle. However, the infusion velocity was slightly unstable, being influenced by the temperature of the infusor. This infusor was used even on an ambulatory basis. According to our results, we thought this infusor is quite useful to improve the quality of life of cancer patients.

Aged↗