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Biomedical subjects

K Sugi

Publications and source records attributed to K Sugi.

At least 127 records · Page 7Linked to original sources
PubMed1988

[Dissecting aortic aneurysm of DeBakey type II diagnosed by color Doppler flow imaging and treated by a Bentall surgical procedure: a case report].

A 33-year-old man with known annuloaortic ectasia was admitted to the hospital because of chest pain. A dissecting aortic aneurysm was strongly suspected, but angiography was not performed because of his history of allergic reaction to iodine contrast material. Two-dimensional echocardiography demonstrated a markedly dilated basal aorta. The aortic wall immediately above the right sinus of Valsalva appeared to divide the aortic lumen into anterior and posterior channels. A defect in the intimal flap with a diameter of two cm was also detected six cm above the aortic ring. Color Doppler flow mapping showed blood flow passing through a probable entrance tear from the true lumen into the false lumen. Reentry could not be detected by Doppler imaging. All major aortic tributaries were presumed patent and supplied via the true lumen. The patient underwent successful emergency Bentall surgical procedure and recovered. It is emphasized that in some cases of DeBakey type I or II aortic dissection, color Doppler flow imaging is helpful for determining indications for emergency surgery.

Adult↗
PubMed1988

[Analbuminemia].

Explore the source record for details and available documents.

Animals↗
PubMed1988

The effect of leukocyte depletion on smoke inhalation injury in sheep.

Leukocytes and the production of oxygen radicals and proteolytic enzymes have been implicated in the pathogenesis of lung injury after smoke inhalation. We investigated the mechanism responsible for this form of pulmonary damage in chronically prepared sheep previously made leukopenic with intra-arterial infusions of nitrogen mustard (mechlorethamine hydrochloride). A control air insufflated group (sham: n = 6), a cotton smoke insufflated group (smoke: n = 12), and a leukopenic cotton smoke insufflation group (smoked + depleted: n = 6) were compared. Although both smoke insufflation groups had equivalent smoke exposure, which was indexed by carboxyhemoglobin, the smoked + depleted group had significant attenuation in the increases in pulmonary artery pressure, pulmonary vascular resistance, and pulmonary lymph flow. The PaO2 to FiO2 ratio (P:F) did not fall to the same extent, nor was there a fall in PaO2. The production of oxygen radicals, which was measured as plasma-conjugated dienes, and the consumption of antiprotease, as measured by alpha 2-macroglobulin levels in lung lymph, were not changed in the smoked + depleted group, whereas it was elevated in the smoked group. We conclude that circulating leukocytes and the release of oxygen radicals and proteolytic enzymes contribute to the lung injury, pulmonary microvascular permeability increase, and pulmonary edema seen after smoke inhalation.

Animals↗
PubMed1987

Effects of propafenone on sinus nodal and ventricular automaticity: in vitro and in vivo correlation.

The electrophysiologic effects of the new antiarrhythmic drug, propafenone, were evaluated in anesthetized closed-chest dogs and on isolated cardiac tissues with the microelectrode technique. Propafenone (2 to 4 mg/kg intravenously) had no effect on sinus rate or on sinus nodal recovery time, but caused a dose-dependent significant decrease in the rate of idioventricular rhythm and increased the duration of ventricular overdrive suppression in dogs (n = 8) with complete atrioventricular block. On isolated canine Purkinje fibers (n = 8) manifesting automaticity with resting membrane potential less negative than -70 mV, propafenone reduced the slope of phase 4 depolarization and reduced the rate of automatic impulse initiation in a concentration-dependent manner (10(-6) M-4.10(-5) M). At these concentrations, propafenone had no effect on rabbit sinus nodal automaticity (n = 8) or on sinoatrial conduction. However, significant depression of sinus nodal automaticity occurred with propafenone concentrations above 5.10(-6) M in the presence of cholinergic or complete autonomic blockade with atropine (10(-6) M) and propranolol (5.10(-5) M). Propafenone caused a concentration-dependent decrease in the disparity of Purkinje fiber-ventricular muscle action potential duration (APD), mainly by shortening Purkinje fiber APD. We conclude: that propafenone suppresses idioventricular rhythm in the intact dog, most likely by depressing Purkinje fiber automaticity; the depressant effect of propafenone on sinus nodal automaticity is evident only during cholinergic receptor blockade; and the antiarrhythmic properties of propafenone may include removal of APD disparity by selective shortening of Purkinje fiber and not of ventricular muscle APD.

Animals↗
PubMed1987

Cellular electrophysiologic characteristics of surviving subendocardial fibers in chronically infarcted right ventricular myocardium susceptible to inducible sustained ventricular tachycardia.

Permanent occlusion of the right coronary artery (RCA) is associated with inducible sustained ventricular tachyarrhythmias (VT) during days 3 to 10 post RCA occlusion period in the conscious dog; VT could no longer be induced beyond this post occlusion period. The aims of the present study were to determine if subendocardial (SE) fibers in the infarcted right ventricle (RVI) during both inducible and noninducible phases of VT remain viable, and if so, to characterize their transmembrane potential properties with the microelectrode and to assess their morphologic features. The RCA was occluded in 13 closed-chest anesthetized dogs with intracoronary balloon inflation. In one group (N = 7), the infarcted tissues were isolated during the VT inducible phase and in another group (N = 6) these tissues were isolated during the VT noninducible phase. Resting membrane potential, action potential amplitude, maximum upstroke velocity, and action potential duration of the surviving SE Purkinje fibers (PF) and ventricular muscle (VM) in the IZ (first layer) were not significantly different in the two groups. Conduction velocity for both basic and premature stimuli from the base to the apex were similar in the two groups. Rapid stimulation at cycle lengths of 300 to 200 msec failed to induce triggering of automatic activity in the two groups. Electron microscopy of SEPF in the IZ showed a drastic reduction in cytosolic lipid droplet accumulation when compared to 24-hour-old infarct. We conclude that: (1) SEPF and VM network in the infarct zone remain electrically viable during the chronic phase of RVI; (2) transmembrane potential properties of this fiber network remain constant and independent of temporal changes of VT inductibility; and (3) ultrastructural improvement of this fiber network suggests an evolution toward normalcy.

Action Potentials↗
PubMed1987

Indication of aorto-coronary bypass graft surgery for infarction area of myocardium considered from exercise thallium-201 myocardial imagings.

To assess accurately the indication and effects of aorto-coronary bypass graft surgery (ACBG) to the myocardium infarction area, 35 patients with myocardial infarction were analyzed by using exercise thallium-201 myocardial imagings. The patients were classified into group I (18 cases) and group II (17 cases) before ACBG. Group I consisted of patients with regional hypoperfusion in the initial image who showed redistribution in the delayed image to the infarction area of myocardium. Group II consisted of those with regional hypoperfusion in the initial image without redistribution in the delayed image. Group I showed a significant improvement in myocardial perfusion (p less than 0.01), pressure rate product (p less than 0.01), global left ventricular ejection fraction (p less than 0.01), segmental wall motion abnormality (p less than 0.01), and exercise tolerance when compared with those of group II before and after ACBG. The above study showed that the pre- operative redistribution of the infarction area in the delayed image suggests myocardial viability and ACBG will be effective.

Coronary Angiography↗
PubMed1987

[Quantitative evaluation of regional myocardial blood flow by digital subtraction angiography: correlations with exercise electrocardiography and Tl-201 myocardial scintigraphy].

We previously reported that the contrast disappearance half-life (T1/2) derived by the computerized washout analysis of digital subtraction coronary arteriograms provides a useful index for quantitatively evaluating regional myocardial blood flow. In the present study, we further evaluated the clinical usefulness of T1/2, comparing it with exercise electrocardiography and exercise thallium-201 myocardial scintigraphy. The study subjects consisted of 25 patients with angina pectoris and 14 patients with normal coronary arteries. Following the manual injection of contrast media into the left anterior descending coronary artery (LAD), a time-density curve was generated in the sectors of the myocardium which were perfused by the LAD and the T1/2 was calculated. T1/2 values correlated closely with double product (r = -0.73). They were significantly greater in patients with exercise-induced ST depression (8.3 +/- 1.0 vs 5.8 +/- 0.7, p less than 0.005). In addition, there was a good correlation between T1/2 values and washout ratio as determined by exercise thallium-201 myocardial scintigraphy, with r = -0.83. Although T1/2 values were within the normal range (mean +/- 2SD of control subjects) in all patients with LAD stenosis of 50 percent or less, these values were abnormally increased, exceeding the normal range, in 11 of the 12 patients with stenosis of 90 percent or more. Compared with exercise electrocardiography, T1/2 values were abnormally prolonged in 11 of the 13 patients with exercise-induced ST depression. Compared with exercise thallium-201 myocardial scintigraphy, T1/2 values were abnormally prolonged in seven of the nine patients with transient perfusion defects.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗
PubMed1987

[Videodensitometric assessment of right and left ventricular functions by digital subtraction angiography].

Right and left ventricular volumes and systolic indices were determined by intravenous digital subtraction ventriculography in 50 patients with various heart diseases. Using a constant injection speed of 35 ml Renografin-76 contrast medium, serial right and left ventriculograms were obtained in the 30 degree right anterior oblique projection. Right ventriculograms were also obtained in the 60 degree left anterior oblique projection. The videotape recordings of subtracted images were continuously digitized into 128 X 128 eight bit (256 gray scales) pixel matrices using an image-processing computer. The endocardial outlines of the right and left ventricles were drawn manually using a joystick, frame by frame, for each cardiac cycle. By integrating overall the pixel densitometric counts within this outline for each frame, the computer generated a time-density curve with maxima and minima represented in the end-diastolic and end-systolic frames, respectively. Systolic indices including ejection fraction (EF), one-third ejection fraction (1/3 EF) and the peak ejection rate (PER) were derived from the time-density curve. Right ventricular volume was determined by the single-plane or biplane mathematical formulae of Ferlinz et al., and left ventricular volume was calculated by the area-length method in the 30 degree right anterior oblique projection. Results by the two geometric methods correlated well for right ventricular volume (r = 0.84) and for EF (r = 0.80). Right ventricular densitometric counts correlated closely with single-plane volume (r = 0.91). Right ventricular ejection fraction (RVEF) determined by videodensitometry also correlated satisfactorily with that by single-plane angiography (r = 0.74).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

[Thallium-201 scintigraphy of the myocardium during exertion in the indication for aortocoronary bypass of an area in the myocardium, the site of an infarct].

The purpose of this study is to precisely evaluate the indications and the results of direct revascularization surgery in a myocardial area previously infarcted. 35 cases were analyzed using thallium scintigraphy during stress. Before surgery, the patients were divided in two groups. Group I (18 cases) includes patients who presented initially a regional hypoperfusion and a reperfusion at the site of the infarction, on late scintigrams; group II (17 cases) also presented a regional hypoperfusion initially, but showed no reperfusion on late scintigrams. Concerning the results during stress, the thallium 201 scintigrams during exercise show alterations of the myocardial perfusion in the infarcted area, before and after surgery; in group I, a significant improvement (p less than 0.01) is noted in the entire group, i.e. 16 patients (88.9%), except in 2 cases where the graft was occluded, and group II shows an improvement in only 4 cases (NS) after surgery. Concerning the modifications of the product pressure X cardiac rhythm, there is a significant improvement (p less than 0.01) in group I (14 out of 18 patients (77.8%)); 2 out of 4 patients who were aggravated, presented occluded grafts after surgery. Group II shows an improvement in 10 out of 17 patients (58.8%) after surgery (NS). The left ventriculography demonstrates alterations in the global ejection fraction. Group I shows a significant improvement in 15 out of 18 patients (88.3%) (p 0.01); in group II there is improvement in 11 out of 17 patients (64.7%) (NS) after surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

The efficacy of lidocaine and verapamil alone and in combination on spontaneously occurring automatic ventricular tachycardia in conscious dogs one day after right coronary artery occlusion.

Occlusion of the right coronary artery (RCA) in the dog is associated with spontaneous sustained ventricular tachycardia (VT) during the 18 to 26 hours post occlusion period. Electrophysiologic studies suggest that these tachycardias are caused mainly by an automatic mechanism. In the present study we evaluated in 16 conscious dogs with VT 1 day after RCA occlusion the efficacy of (1) lidocaine (L), which depresses primarily the mechanism of enhanced normal automaticity; (2) verapamil (V), which depresses the mechanism of abnormal and triggered automaticity; and (3) combination of both L and V on these VTs. The RCA was occluded in 16 anesthetized closed-chest dogs by intracoronary balloon inflation. All 16 dogs had spontaneous VT while in the conscious state during the 18 to 26 hours post occlusion study period. L (5 mg/kg intravenously) bolus restored within 1 minute normal sinus rhythm (NSR), with a mean rate of 118 +/- 14 bpm, in dogs (n = 7) which had their VTs overdrive suppressed and had a mean rate of 145 +/- 14 bpm (range 110 to 150 bpm). L was ineffective in dogs (n = 9) which did not have their VTs overdrive suppressed and had a mean VT rate of 192 +/- 24 bpm (range 175 to 250 bpm). In contrast, however, V (0.15 mg/kg intravenously) was ineffective in all seven dogs with the slower VT rates, but was effective in restoring NSR with a mean rate of 140 +/- 14 bpm in six out of nine dogs with the faster VT rates.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

The efficacy of cibenzoline and propafenone against inducible sustained and nonsustained ventricular tachycardias in conscious dogs with isolated chronic right ventricular infarction: a comparative study with procainamide.

The efficacy of intravenous cibenzoline (3 mg/kg), propafenone (4 mg/kg), and procainamide (20 mg/kg) against inducible sustained and nonsustained ventricular tachycardias (VT) was evaluated in 12 conscious dogs with chronic isolated right ventricular (RV) infarction. RV infarct was caused by permanent occlusion of the right coronary artery in the closed-chest dog by intracoronary balloon inflation. Three to 10 days following the occlusion period, programmed electrical stimulation reproducibly induced sustained and/or nonsustained VT, allowing evaluation of antiarrhythmic drug efficacy. Propafenone was effective in preventing the induction of sustained VT in only one out of six dogs tested, but caused a significant (p less than 0.05) slowing of VT rate (269 +/- 13 to 230 +/- 10 bpm). Procainamide had effects similar to those seen with propafenone. Propafenone and procainamide were ineffective against nonsustained VT, and on established sustained VT once induced. Cibenzoline was effective in preventing the induction of sustained VT in two out of seven dogs, an effect which was not significantly different from either propafenone or procainamide. However, cibenzoline was significantly (p less than 0.05) more effective than either procainamide or propafenone in terminating an established induced sustained VT (four out of six dogs). Furthermore, cibenzoline converted nonsustained to sustained VT in four out of seven dogs tested. Histopathologic studies have shown infarction of the basal two thirds of the RV (38.5 +/- 7.8% of the RV) with no left ventricular involvement. It is concluded that the isolated RV infarction model is highly suitable for serial drug testing against inducible VT in conscious dogs, and this model of VT appears to be fairly resistant to standard and newer antiarrhythmic drug therapy.

Animals↗
PubMed1986

Inducible sustained ventricular tachycardia and ventricular fibrillation in conscious dogs with isolated right ventricular infarction: relation to infarct structure.

The susceptibility of infarcted right ventricular myocardium to inducible ventricular tachyarrhythmias was serially evaluated in 18 conscious dogs during the first 2 weeks after permanent right coronary artery occlusion. Properly timed double premature stimuli applied to the right ventricular outflow tract induced sustained (longer than 1 minute) ventricular tachycardia at rates of 190 to 400 beats/min in nine dogs, and ventricular fibrillation in six dogs. No ventricular arrhythmias could be induced in the remaining three dogs. The zone of premature coupling intervals within which ventricular tachyarrhythmias could be induced decreased in each dog as the infarct aged, and by day 12 after occlusion, no ventricular arrhythmias could be induced in any of the dogs studied. Both the size and the degree of patchiness (graded from 0 for no patchiness to +4 for patchiness throughout the infarct) of the infarct appear to be related to the nature of the induced rhythm. Infarcts with greater heterogeneity and those that were larger than 8% of the right ventricular volume were associated with a higher incidence of ventricular fibrillation, and infarcts with a lesser degree of patchiness were more suitable for sustained ventricular tachycardia (3.4 +/- 1.2 versus 1.4 +/- 0.4, p less than 0.05). These findings indicate that the infarcted right ventricular myocardium, independent of left ventricular involvement, can be associated with malignant ventricular tachyarrhythmias, ventricular tachyarrhythmias can be induced only during a well defined postinfarction period; and both the size and geometry of the right ventricular infarct determine the nature of the induced ventricular rhythm.

Animals↗