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Biomedical subjects

T Tomaru

Publications and source records attributed to T Tomaru.

At least 91 records · Page 5Linked to original sources
PubMed1988

Fiberoptic angioscopy of cardiac chambers, valves, and great vessels using a guiding balloon catheter in dogs.

The applicability of fiberoptic angioscopy with a guiding balloon catheter to observe the cardiac chambers, valves and the great vessels was examined in anesthetized dogs. A No. 11 French guiding balloon catheter (balloon diameter 50 French) was introduced through either the right jugular vein or the right femoral vein into the right heart, and then a fiberscope (4.3 French in diameter) was introduced through the catheter into the right heart in 10 dogs. The balloon was inflated with air and gently pushed against the luminal surface, warm saline was infused through the catheter to displace the blood, and the luminal surfaces were photographed on 16 mm color cinefilms. Pulmonary angioscopy was also performed in these dogs. Similarly, the guiding catheter and fiberscope were introduced through the right common carotid artery into the left ventricle for observation of the luminal changes in the other 10 dogs. The luminal surfaces of the superior vena cava, right atrium, right ventricle, and pulmonary artery could be observed in all dogs. The trabeculae of the left ventricle, contracting and relaxing synchronously with the cardiac beat, could also be observed in all dogs. However, observations of the tricuspid valve, aortic valve, papillary muscle, and chordae were successful in only some dogs. Postmortem examinations revealed no obvious endocardial or intimal damage. The results indicate the applicability and safety of angioscopy guided by a balloon catheter for observations of the luminal changes in the cardiac chambers and great vessels.

Animals↗
PubMed1988

Fiberoptic study on the effects of transluminal angioplasty in experimental occlusive arterial thrombosis.

Percutaneous transluminal coronary angioplasty has been proposed as definitive therapy for coronary recanalization of occluded coronary arteries in patients with acute myocardial infarction (AMI). The effects of transluminal angioplasty (TA) on experimental occlusive canine arterial thrombi that closely simulated the clinical condition was examined by a fiberoptic method. Experimental arterial thrombosis was produced by endothelial denudation and induction of luminal stenosis. Eighteen dogs that showed total occlusion of the iliac artery with thrombi were evaluated. Seven dogs (group A) with 6-hour-old thrombi received 20,000 IU/kg intravenous urokinase (UK) but did not show recanalization. TA was performed with a Gruentzig or Simpson-Robert balloon catheter and its effect was evaluated by a vascular fibroscope. Eight dogs (group B) with 6-hour-old thrombi underwent primary TA. After TA, less than 50% luminal obstruction with residual thrombi was visualized in five dogs (71%) of group A and four dogs (50%) of group B. Residual thrombi showed a doughnut-like or globular type shape and consisted of dense fibrin networks and compact platelet aggregates. All dogs in group B received 20,000 IU/kg intravenous UK after TA, but most of them showed progression of thrombus size despite UK infusion. In conclusion, the results suggest (1) that TA is effective in recanalization of an occluded artery with aged thrombus that is resistant to thrombolytic therapy and (2) that vascular fiberscope is a useful method for evaluation of the effects of TA on occlusive arterial thrombus.

Angioplasty, Balloon↗
PubMed1988

[The effects of TMB-8, an intracellular Ca2+ antagonist, on impaired left ventricular relaxation by global ischemia in dog].

The effects of TMB-8, an inhibitor of Ca2+ release from the intracellular store site, on impaired left ventricular relaxation caused by global ischemia were examined in 45 anesthetized dogs. In the non-ischemic group, the intracoronary infusion of 100 micrograms/min TMB-8 suppressed the decrease in T, an index of left ventricular relaxation, by increasing the atrial pacing rate. In the ischemic group, the intracoronary infusion of 30 and 100 micrograms/min TMB-8 suppressed the increases of T and left ventricular end-diastolic pressure caused by ischemia and increase of pacing rate. The results indicate that TMB-8 suppresses the ability of relaxation in non-ischemic myocardium and prevents the impairment of left ventricular relaxation induced by left ventricular global ischemia.

Animals↗
PubMed1988

[Effects of 3,4-diaminopyridine on the contractions of guinea-pig tracheal smooth muscle induced by histamine and prostaglandin D2].

Effects of 3,4-diaminopyridine (DAP), which decreases the membrane K conductance, on the contractions of guinea-pig tracheal smooth muscle induced by histamine and prostaglandin D2 (PGD2) were investigated. Pretreatments with 5 X 10(-4) and 10(-3) M DAP increased the excitability of histamine-induced contraction. The increment of the excitability by DAP was not suppressed by tetrodotoxin (TTX), but by nifedipine (Nif). Pretreatment with 10(-3) M DAP did not affect the contraction induced by PGD2. The results suggest that DAP increases the excitability of histamine-induced contraction by activating the voltage-dependent Ca channels and that PGD2 contracts tracheal smooth muscle through a mechanism different from that of histamine.

4-Aminopyridine↗
PubMed1988

[Effects of prazosin, SGB-1534, dobutamine and isoproterenol on congestive heart failure in dogs].

Effects of prazosin, dobutamine, isoproterenol and SGB-1534, a new alpha-blockade, on congestive heart failure (CHF) in dogs were investigated. The model was made by protease injection into the left ventricular free wall, saline loading, and dextran and methoxamine infusions. By this maneuver, left atrial pressure (LAP), systemic vascular resistance (SVR) and left ventricular end-diastolic pressure (LVEDP) were markedly increased, aortic blood flow (AoBF) was decreased, and systemic blood pressure was unchanged. In this model, the intravenous administration of prazosin (0.1 approximately 10.0 micrograms/kg, i.v.) increased AoBF and decreased LAP in a dose-dependent manner. The improvement of the CHF by prazosin was considered to result from its vasodilating action. SGB-1534 (0.1 approximately 10.0 micrograms/kg, i.v.) improved the CHF mainly through its vasodilating and positive inotropic actions, which is because SGB-1534 decreased SVR and increased Vmax. The magnitudes of vasodilation by SGB-1534 was greater than those by prazosin. These data indicate that SGB-1534 is useful in the treatment of CHF. Both dobutamine (5 approximately 100 micrograms/kg, i.v.) and isoproterenol (0.001 approximately 0.1 micrograms/kg, i.v.) improved the CHF through their vasodilating and positive inotropic actions in the canine CHF. The ratio of positive inotropism/vasodilation was greater for dobutamine than isoproterenol. The vasoconstriction by the large dose of dobutamine might participate in this difference between dobutamine and isoproterenol.

Adrenergic alpha-Antagonists↗
PubMed1988

Pathologic study of myocardial infarction of the right ventricle.

To evaluate pathologic features of myocardial infarction of the right ventricle (MI-RV), we analyzed 106 autopsy cases with transmural myocardial infarction (MI) (fresh in 46 cases and healed in 60). Anterior MI was observed in 47, posterior MI in 54 and lateral in 5. There were 13 cases (12%) with MI-RV (anterior in 1 case and posterior in 12), which included 10 cases with fresh MI and 3 with healed MI. All cases with MI-RV had associated transmural interventricular septal infarction. Of the 13 cases with MI-RV, 9 (69%) had right ventricular dilatation (RVD) and 2 had right ventricular hypertrophy. Extensive MI-RV (more than 1/3 of the right ventricle) was observed in 8 (89%) of those with RVD. Of 93 cases of MI without MI-RV, 14 (16%) had RVD. The incidence of RVD was greater in cases with MI-RV than in those without (p less than 0.005). All 12 cases with posterior MI-RV had significant (greater than or equal to 75%) narrowing of the right coronary artery (RCA), and 19 cases (87%) of those with posterior MI without MI-RV, had similar lesions. In conclusion, the incidence of RVD and significant narrowing of RCA was greater in cases with posterior MI-RV than in those with posterior MI.

Adult↗
PubMed1988

The multifactorial etiology of mitral valve prolapse, a new entity of postinflammatory mitral valve prolapse.

As etiologic factors for mitral valve prolapse, papillary muscle dysfunction due to coronary artery disease, hypertrophic obstructive cardiomyopathy, atrial septal defect and trauma have been reported. Connective tissue diseases such as Marfan's syndrome. Ehlers-Danlos syndrome or Turner's syndrome may also result in mitral valve prolapse. In the majority of patients with mitral valve prolapse, however, the etiology is unknown, in which case the condition is considered primary or idiopathic. We evaluated 33 consecutive surgically-excised mitral valves removed from patients with regurgitant prolapsing mitral valves and congestive heart failure. On microscopic examination, myxomatous degeneration was observed in 14 cases, postinflammatory changes, however, were seen in the other 19 cases and included diffuse vascularization with thick-walled vessels, round-cell infiltration and destruction of valve architecture. These valves showed a varying degree of doming and/or interchordal hooding as well as an increased surface area. Elongated chordae tendineae were seen in 37%, chordal rupture in 16% of the patients. Slightly fused chordae tendineae, minimal commissural fusion and/or fibrous thickening of cusps were also observed, findings which simulate closely rheumatic valvulitis. Patients with postinflammatory mitral valve prolapse were younger at the time of operation and at the onset of symptoms, had smaller surface areas of the anterior mitral leaflet and more marked leaflet thickening than patients with myxomatous mitral valve prolapse. The results of the study show that mitral valve prolapse in patients with severe mitral regurgitation can be attributed to postinflammatory changes; we suggest, therefore, the term "postinflammatory valve prolapse". Postinflammatory mitral valve prolapse may be due to manifest or subclinical rheumatic fever.(ABSTRACT TRUNCATED AT 250 WORDS)

Chordae Tendineae↗
PubMed1987

Angiographic and angioscopic observations of the arterial luminal changes induced by vasospasm.

Angiography and angioscopy were used to examine arterial luminal changes induced by experimental vasospasm. The right common carotid artery of the dog was perfused with Krebs-Henseleit solution at a constant pressure, 3,4-diaminopyridine (DAP), a selective potassium channel blocker was applied on the adventitia, and the luminal changes were observed with angiography and angioscopy. Angiographically vasospasm (defined as a reduction in the internal diameter to less than 50% of the control value) was always induced by the topical application of 5 X 10(-1) mol/L DAP. The internal diameter decreased to 25% +/- 7% (mean +/- standard error, n = 6) 15 minutes after the application. The vasospasms propagated 2.7 +/- 0.6 and 1.1 +/- 0.3 cm downstream and upstream, respectively. Angioscopy showed that the lumen narrowed gradually and concentrically. Perfusion of the artery during vasospasm for 15 minutes with a backflow of blood from the contralateral artery resulted in thrombosis at the spastic segment. The results indicate that carotid vasospasm can be constantly induced by DAP, thrombosis occurs in the spastic artery, and angioscopy is useful for serial observation of the luminal changes induced by vasospasm.

4-Aminopyridine↗
PubMed1987

Percutaneous coronary angioscopy in patients with ischemic heart disease.

Percutaneous transluminal coronary angioscopy was performed during routine coronary angiography in seven patients and during PTCA in one patient with ischemic heart disease. A flexible fiberscope with an external diameter of 1.4 mm was introduced through an 8F or 9F guiding catheter used for PTCA into the coronary arteries. Warmed saline solution (15 to 20 ml) was injected through the guiding catheter into the coronary arteries for replacement of blood. Twenty-one of the 31 coronary segments were visualized and photographed on color cinefilms. The lumen of the atherosclerotic segment showed narrowing with smooth surface or with spiral folds. PTCA caused dilatation of the stenosed segment with scattered thin thrombi. These findings indicate the usefulness of angioscopy to observe luminal changes in the coronary arteries of patients with ischemic heart disease.

Aged↗
PubMed1987

Experimental canine arterial thrombus formation and thrombolysis: a fiberoptic study.

We produced arterial thrombi that simulated the clinical condition in canine iliac arteries by endothelial denudation and partial occlusion. The processes of thrombus formation and thrombolysis were examined by vascular fiberscope. Laminar mural thrombi developed in all 21 preparations 10 minutes after blood reperfusion, with stenosis formation. Over 50% luminal obstruction with thrombi occurred in 10 preparations 30 minutes after inducing stenosis. Total occlusion with thrombi occurred in four preparation (31%) at 1 hour, and in all nine at 3 hours after inducing stenosis. Usually, red thrombus at the denudated region grew in size distal to the sited of stenosis. Histologically, thrombi of less than 1 hour duration consisted of a loose fibrin network and those of over 3 hours' duration consisted of a dense fibrin network. Infusion of 144,000 IU of urokinase (UK) reduced the size of thrombi less than 1 hour old during fiberoptic observation. However, UK infusion of similar dose failed to recanalize two of four preparations with 3-hour-old thrombi. In conclusion, arterial thrombi that closely simulate those observed clinically can be made by endothelial denudation and partial occlusion, and the vascular fiberscope provides a useful method for analysis of thrombosis and thrombolysis.

Animals↗
PubMed1987

Postinflammatory mitral and aortic valve prolapse: a clinical and pathological study.

In this study we reevaluated whether the sole cause of mitral valve prolapse (MVP) and aortic valve prolapse (AVP) is myxomatous degeneration. Forty-two surgical cases of prolapsed valves with mitral and/or aortic regurgitation were reviewed (AVP in nine, MVP in 27, and combined AVP and MVP [CVP] in six). On microscopic examination, myxomatous degeneration was observed in 20 patients, including six with AVP, 13 with MVP, and one with CVP. In the other 22 patients, including three with AVP, 14 with MVP, and five with CVP, microscopic examination revealed fibrosis with vascularization and scattered infiltration of inflammatory round cells caused by postinflammatory changes with or without chronic inflammation. We coined the term "postinflammatory valve prolapse" (PIVP) to describe these valves. Both postinflammatory and myxomatous degeneration were observed in seven patients with floppy mitral valves attributable to PIVP. Rupture of chordae tendineae was present in six patients with myxomatous mitral valve and three with PIVP. Seven patients with PIVP had a history of rheumatic fever. The results suggest that valvular prolapse is produced not only by myxomatous degeneration but also by postinflammatory changes, including those caused by rheumatic fever.

Adult↗
PubMed1987

[Effects of alpha-human atrial natriuretic polypeptide (alpha-hANP) on congestive heart failure in dogs].

Effects of alpha-human atrial natriuretic polypeptide (alpha-hANP) on a model of congestive heart failure (CHF), we established in dogs, were investigated. The model was made by protease injection into the left ventricular free wall, saline loading, and dextran and methoxamine infusion. By this maneuver, left atrial pressure (LAP), systemic vascular resistance (SVR) and left ventricular end-diastolic pressure (LVEDP) were markedly increased, aortic blood flow (AoBF) was decreased and systemic blood pressure (SBP) was unchanged. Following intravenous application of 0.50 microgram/kg alpha-hANP, LAP was reduced from 18.9 to 14.0 mmHg (N = 7, mean); SBP, from 114.4 to 105.1 mmHg; SVR, from 21603 to 15602 dyne sec/cm5; and LVEDP, from 22.2 to 17.6 mmHg; while AoBF was increased from 0.46 to 0.54 l/min. Vmax and T were little influenced. The results indicate that alpha-hANP improved canine CHF mainly through its vasodilating action.

Animals↗
PubMed1986

Fiberoptic observation of thrombosis and thrombolysis in isolated human coronary arteries.

Coronary arteries isolated from cadavers autopsied within 7 hours after death were perfused with canine arterial blood, and the processes of thrombus formation at the segments stenosed with atheroma and the thrombolytic effects of urokinase were investigated by angioscopy. Ten minutes of blood perfusion caused thin mural thrombi localized at the stenotic or nonstenotic segments. During 30 minutes of blood perfusion, the thin mural thrombi of the outlet or inlet of the segment grew into a doughnut-shaped thrombus. Also, the thin mural thrombi in the stenotic segment grew into a streamer-like thrombus and drifted downstream. These thrombi grew in size with increasing perfusion time and finally obstructed the stenotic segment. Globular thrombi close to the outlet also were formed in a few preparations. Unlike the thrombi at the stenotic segment, the mural thrombi in the nonstenotic segments did not grow into massive thrombi. The thrombi were reduced in size within 10 minutes of perfusion with 320 U/ml or more of urokinase. During thrombolysis, sandstorm-like dispersion of the blood cells occurred, small fragments detached from the mother thrombus and flew downstream, or the fibrin core of the thrombus was exposed. The results indicate the usefulness of angioscopy for the dynamic and serial investigation of thrombosis and thrombolysis.

Adult↗
PubMed1986

[Effects of forskolin on canine congestive heart failure].

Forskolin is a diterpene of the labdane family which activates adenylate cyclase. The effects of forskolin were investigated in a congestive heart failure (CHF) model that we newly established using anesthetized dogs. The model was made by the intramural injection of protease into the left ventricular free wall, saline loading, and dextran and methoxamine infusion. By this maneuver, aortic blood flow (AoBF) was decreased; left atrial pressure (LAP), systemic vascular resistance (SVR) and left ventricular endodiastolic pressure (LVEDP) were markedly increased; and systemic blood pressure was unchanged. A bolus injection of 5.0 micrograms/kg forskolin reversed the hemodynamic findings of CHF. It reduced LAP (17.5----7.9 mmHg) (mean, N = 7), SVR (19980----10390 dyne sec/cm5), time constant T (90.7----59.2 msec) and LVEDP (22.8----16.8 mmHg); and it increased Vmax (2.32----2.82 l/sec) and AoBF (0.50----0.72 l/min). Forskolin improved the CHF mainly through its vasodilator and positive inotropic actions.

Animals↗
PubMed1986

Phasic contractions of canine and human coronary arteries induced by potassium channel blockers.

To gain insight into mechanisms underlying phasic coronary vasospasm in patients with variant angina pectoris, we studied whether phasic contractions could be induced in isolated canine and human coronary arteries by agents which block potassium channels. Phasic contractions of canine coronary arteries were always induced by 3,4-diaminopyridine (10(-2) M) and less frequently by 4-aminopyridine (10(-2) M). These agents also caused phasic contractions in human, swine and monkey coronary arteries and in canine basilar, carotid, renal and femoral arteries. The cycle length of phasic coronary contractions ranged from 30 sec to 1 hour, and the developed tension was 2.5 times greater than for potassium contractions. The contractions continued for more than 11 hours. Morphologically, perinuclear vacuolization, a characteristic change of vasospasm, appeared in the coronary smooth muscles. The phasic contractions were not eliminated by tetrodotoxin, atropine, phentolamine or yohimbine, but they were eliminated by nicorandil which activates potassium channels and nifedipine which blocks slow calcium channels. The results indicate that potassium channel blockers can induce phasic arterial contractions.

4-Aminopyridine↗
PubMed1985

[Coronary sinus type atrial septal defect diagnosed by two-dimensional color Doppler echocardiography: a case report].

This is a case report of coronary sinus type atrial septal defect (ASD) diagnosed preoperatively by two-dimensional color Doppler echocardiography. A 22-year-old asymptomatic woman was admitted for preoperative cardiac evaluation. A cardiac murmur and cardiomegaly had been noted at a routine examination which included electrocardiography and chest radiography, and M-mode echocardiography suggested the presence of a secundum type ASD. Color Doppler echocardiography revealed a left to right atrial shunt flow through the coronary sinus ostium into the right atrium. By peripheral contrast echocardiography, a negative contrast echo from the coronary sinus ostium was observed within the right atrium and persistent left superior vena cava was excluded. At operation, a 2 X 3 cm defect was demonstrated at the interatrial septum in the vicinity of the coronary sinus ostium. This is the first reported case of a coronary sinus type ASD diagnosed preoperatively by color Doppler echocardiography.

Adult↗