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Biomedical subjects

S Nanto

Publications and source records attributed to S Nanto.

At least 37 records · Page 2Linked to original sources
PubMed1994

Myocardial salvage: its assessment and prediction by the analysis of serial myocardial contrast echocardiograms in patients with acute myocardial infarction.

It has been difficult to assess myocardial salvage in patients with coronary reflow because of the lack of appropriate methods of determining the risk area and assessing effects of coronary reflow in patients, myocardial contrast echocardiography was performed in 28 patients with acute myocardial infarction before reperfusion, immediately after reperfusion, and in the chronic stage with the right and left coronary arterial injection of sonicated ioxaglate. Contrast-deficit and contrast-filled areas before reperfusion were defined as the risk area and noninfarct area, respectively. If the ratio of peak subtracted gray level in the risk area to that in the noninfarct area was < 0.4, the risk area was taken as a contrast defect. Contrast defect was observed even after reperfusion in 8 (29%) patients, and the defect was consistently observed in the chronic stage in all of them. Contrast defect disappeared after reperfusion in the other 20 patients but reappeared in 4 (20%) of them in the chronic stage despite the patent infarct-related vessel. Left ventricular function recovery of the risk area in the chronic stage as assessed with regional wall motion and wall thickness was better in the patients without contrast defect after reperfusion than in patients with persistent or reappeared contrast defect. In conclusion, (1) myocardial salvage is improbable in patients with contrast defect immediately after reperfusion, (2) contrast enhancement immediately after reperfusion does not necessarily imply myocardial salvage in the chronic stage, and (3) myocardial echocardiography in the chronic stage may provide clinically useful information about myocardial salvage in patients with myocardial infarction.

Adult↗
PubMed1994

Effect of successful angioplasty following thrombolysis on infarct size and left ventricular function.

The role of the angioplasty following thrombolysis in acute myocardial infarction has been discussed in several studies, however the effect of successful angioplasty on infarct size and left ventricular function has not been properly evaluated. Successful reperfusion was achieved in 79 out of 104 patients with primary anterior acute myocardial infarction. These patients were classified as follows, according to the type of intervention during the acute phase: 50 patients in which thrombolysis was successful (the thrombolysis group); 12 patients who underwent successful immediate angioplasty following successful thrombolysis (the immediate angioplasty group); and 17 patients in which rescue angioplasty was successful (the rescue angioplasty group). The 25 patients whose infarct-related vessels were not reperfused after intervention were classified as the non-reperfused group. Infarct size, evaluated as defect volume by T1-201 SPECT, 1 month after the onset, was 840 +/- 154 units (mean +/- S.D.) in the immediate angioplasty group and was similar to that in the thrombolysis group (948 +/- 88 units), but significantly smaller than in the non-reperfused group (1759 +/- 108 units). There were no significant differences in left ventricular function in the immediate angioplasty group and the thrombolysis group. Successful rescue angioplasty did not have any beneficial effect on left ventricular functions or infarct size, when compared with the failed thrombolytic group (1105 +/- 169 units vs. 1617 +/- 169 units). End-diastolic volume (52 +/- 3 ml/m2) in the successful rescue angioplasty group, however, was significantly smaller than in the failed thrombolysis group (67 +/- 3 ml/m2).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Progressive decreases in coronary vein flow during reperfusion in acute myocardial infarction: clinical documentation of the no reflow phenomenon after successful thrombolysis.

OBJECTIVES: This study was undertaken to examine the effects of coronary flow dynamics after thrombolysis on infarct size limitation. BACKGROUND: It has been commonly accepted that early thrombolysis does not necessarily salvage infarcted myocardium. Plausible causes for myocardial necrosis include such factors as elapsed time to reperfusion, residual stenosis, collateral vessels, hemodynamic loads, preconditioning and reperfusion injury. Recently, the no reflow phenomenon has been elucidated to be associated with infarct extension in clinical studies employing contrast echocardiography or thallium scintigraphy. METHODS: Nineteen patients with early reperfusion in acute anterior myocardial infarction and comparable clinical background were studied. The patients were classified into two groups on the basis of pattern of thermodilution measurements of great cardiac vein flow after reperfusion: group A, 9 patients with a progressive decrease in great cardiac vein flow during the 1st 24 h of the onset of infarction; and group B, 10 patients without this observation. Left ventricular ejection fraction and thallium perfusion defect were compared between the two groups at follow-up. RESULTS: There were no significant differences in systemic hemodynamic variables between groups A and B, and neither group had recurrent ischemic events suggesting reocclusion or restenosis during the study. In group A, both great cardiac vein flow (mean +/- SD 44 +/- 17% reduction) and oxygen extraction (38 +/- 15% reduction) were progressively decreased after the onset of reperfusion. Compared with group B, this group showed a lower left ventricular ejection fraction (36 +/- 7% vs. 63 +/- 15%, p < 0.01) and a larger thallium-201 defect severity index (1,091 +/- 366 U vs. 247 +/- 261 U, p < 0.01) at follow-up. Although other patient characteristics were comparable between the two groups, antecedent angina occurred in 90% of group B patients in contrast to only 33% of group A patients. CONCLUSIONS: Salvage of myocardium from infarction by successful thrombolysis was not observed in the patients demonstrating progressive decreases in great cardiac vein flow (group A). In those patients, inadequate myocardial reperfusion on a microvascular basis might be associated with a much larger myocardial infarction. Antecedent angina may protect against a progressive decrease in coronary flow and may have beneficial effects on infarct size limitation.

Adult↗
PubMed1994

Neointimal coverage of stents in human coronary arteries observed by angioscopy.

OBJECTIVES: The aim of this study was to reveal the time course of the neointimal coverage of stents placed in the human coronary arteries. BACKGROUND: In deciding the protocol of anticoagulant and antiplatelet therapy for patients who undergo stent implantation, the condition of the neointimal coverage of stents should be taken into consideration. However, the time course of the neointimal coverage of stents has not been elucidated in human coronary arteries. METHODS: Serial angioscopic observations were performed immediately after stenting, at 8 to 45 days (short-term follow-up) and at 65 to 142 days (long-term follow-up) in patients who underwent implantation of the Wiktor coronary stent in the restenotic lesion or in the lesion of acute or threatened closure after balloon angioplasty. RESULTS: Angioscopic observations were successfully performed in 14 cases immediately after stenting, in 11 cases at short-term follow-up and in 13 cases at long-term follow-up. Immediately after stenting and even at 8 to 18 days after stenting, the stent was not covered by the neointimal layer in any case. However, at 65 to 142 days after stenting, the stent was covered by the neointimal layer in all cases. Angioscopically, three types of neointimal layer were recognized: a white layer with a cottonlike surface in three cases, a white layer with a smooth surface in eight cases and a transparent layer with a smooth surface in two cases. CONCLUSIONS: Although some experimental results in animals have shown completion of neointimal coverage of stents in a few weeks, in this serial angioscopic follow-up study, the completion of neointimal coverage of stents in human coronary arteries required approximately 3 months.

Angioscopy↗
PubMed1993

Supported angioplasty with synchronized retroperfusion in high-risk patients with left main trunk or near left main trunk obstruction.

To test the feasibility of synchronized retroperfusion (SRP) as a support device of percutaneous transluminal coronary angioplasty (PTCA) for high-risk patients, 10 patients with left main trunk or near left main trunk obstruction underwent PTCA with SRP. An 8.5F retroperfusion catheter was inserted from the antecubital vein into the coronary sinus. Arterial blood was supplied through the catheter into the myocardium with a retroperfusion pump during the diastolic phase by means of ECG triggering. In all patients, the narrowings were successfully dilated and an improvement of more than 20% in the luminal diameter stenosis was achieved; however, narrowing of more than 50% (58%) remained in one patient. In all patients, systemic hemodynamics was maintained for more than 30 seconds during balloon inflation. In seven patients, a 60-second balloon inflation was possible without any collapse of systemic hemodynamics. To test the protective effect of SRP on myocardial ischemia and impairment of systemic hemodynamics, balloon inflation without SRP was performed in eight patients after successful dilatation. The duration for balloon inflation with SRP (71 +/- 30 seconds; n = 8) was significantly longer than that without SRP (56 +/- 30 seconds; n = 8). The decrease in systolic aortic pressure, the increase in pulmonary diastolic pressure, and ST-T segment elevation in the precordial lead of ECG during balloon inflation with SRP were less than those during balloon inflation without SRP. After PTCA, angina was not provoked by exercise stress testing in any of the 10 patients. We concluded that SRP is a beneficial support device of PTCA for high-risk patients.

Aged↗
PubMed1993

Myocardial hibernation in the infarcted region cannot be assessed from the presence of stress-induced ischemia: usefulness of delayed image of exercise thallium-201 scintigraphy.

To examine the relationship between the improvement of wall motion in infarcted regions after percutaneous transluminal coronary angioplasty (PTCA) and thallium-201 uptake in the delayed image of exercise thallium-201 scintigraphy before PTCA, 14 patients with anterior old myocardial infarction were studied. Exercise thallium-201 scintigraphy was performed before PTCA of left anterior descending artery, and mean percent thallium-201 uptake of abnormal segments was calculated in the initial and 4-hour delayed images. Left ventricular angiography was performed during catheterization, before, and 4 to 13 months after PTCA; and regional ejection fraction of anterior wall was calculated. Atrial pacing stress test with the measurement of lactate concentration of aorta and great cardiac vein was performed during catheterization before PTCA. In five patients with mean percent thallium-201 uptake in the delayed image < or = 50% (group I), regional ejection fraction did not increase after PTCA (23% +/- 9% to 24% +/- 12%). In the other nine patients with mean percent thallium-201 uptake > 50% (group II), regional ejection fraction increased significantly after PTCA (39% +/- 18% to 47% +/- 14%; p < 0.05). There was no significant difference in regional ejection fraction, lactate extraction ratio during maximal pacing, and the redistribution of exercise thallium-201 scintigraphy between the two groups before PTCA. Thus the delayed image before PTCA is useful to detect reversible nonfunctioning viable myocardium (hibernating myocardium) in the infarcted region. However, the wall-motion abnormality and the degree of stress-induced ischemia in the infarcted region before PTCA may not be necessarily useful for the detection of hibernating myocardium.

Aged↗
PubMed1993

Demonstration of functional border zone with myocardial contrast echocardiography in human hearts. Simultaneous analysis of myocardial perfusion and wall motion abnormalities.

BACKGROUND: Although the presence of a functional border zone (FBZ), defined as the nonischemic but asynergic myocardium adjacent to the ischemic area, has been demonstrated in animal hearts, it is not known whether this zone exists in humans. METHODS AND RESULTS: Myocardial contrast echocardiography (MCE) was performed before and during balloon inflation in the area of coronary stenosis by injecting contrast medium through the guiding catheter in 13 patients with effort angina who underwent successful coronary angioplasty. The area showing MCE defect during balloon inflation was determined with reference to the preangioplasty MCE and was regarded as an ischemic area. The size of the FBZ was assessed by measuring the length of the endocardium that showed asynergy in the echo-enhanced (nonischemic) area. The FBZ measured was 13 +/- 4 mm in the short-axis view (n = 5) and 16 +/- 9 mm in the long-axis view (n = 8). CONCLUSIONS: Nonischemic contractile dysfunction exists even in human hearts. The presence of an FBZ may limit the use of wall motion analysis in assessing the risk or ischemic area in patients with myocardial infarction. MCE appears to be a unique technique for assessing the risk or ischemic area.

Adult↗
PubMed1993

Late reperfusion for acute myocardial infarction limits the dilatation of left ventricle without the reduction of infarct size.

BACKGROUND: While previous clinical studies have shown a possible beneficial effect of the reperfusion performed at a relatively late phase of acute myocardial infarction ("late reperfusion") in preventing left ventricular enlargement, the mechanism has not been clarified. METHODS AND RESULTS: Of 89 patients with an initial anterior myocardial infarction, reperfusion was successful in 69. These 69 were divided into three groups according to the time required to achieve reperfusion after the onset of symptoms: early-reperfused (< 3 hours from the onset to reperfusion; n = 22), intermediate-reperfused (3 to 6 hours from the onset to reperfusion; n = 28), and late-reperfused (> 6 hours from the onset to reperfusion; n = 19). The 20 patients whose infarct-related artery were occluded in the acute phase as well as 1 month later was classified as nonreperfused. Infarct size, evaluated as defect volume by 201Tl single-photon emission computed tomography 1 month after the onset, was 1593 +/- 652 units (mean +/- SD) in the late-reperfused group, significantly larger (P < .05) than that of the intermediate-reperfused (1066 +/- 546 U) or the early-reperfused groups (372 +/- 453 U) but not different from that of the nonreperfused group (1736 +/- 562 U). Wall motion abnormality index as well as global ejection fraction evaluated by left ventriculography 1 month after the onset showed that late reperfusion did not preserve the left ventricular wall motion and function. These results indicate that the earlier reperfusion decreased the size of the infarction and preserved left ventricular function, whereas late reperfusion (> 6 hours after onset) did not limit infarct size or preserve left ventricular function. In contrast, the end-diastolic volume index did not differ significantly among the early-reperfused (50 +/- 15 mL/m2), intermediate-reperfused (54 +/- 14 mL/m2), and late-reperfused (53 +/- 19 mL/m2) groups; those were significantly smaller than that of the nonreperfused group (68 +/- 12 mL/m2; P < .05). Left ventriculographic data obtained in both the acute and chronic phase in 39 patients showed that left ventricular volumes increased significantly during the course of myocardial infarction only in the nonreperfused group. CONCLUSIONS: Late reperfusion appeared to prevent ventricular dilatation acute myocardial infarction independent of the limitation of infarct size.

Adult↗
PubMed1992

Temporal increase in resting coronary blood flow causes an impairment of coronary flow reserve after coronary angioplasty.

Impaired coronary flow reserve immediately after coronary angioplasty may be attributed to an increase in resting coronary blood flow. To test this hypothesis we measured great cardiac venous flow (GCVF) at rest and during rapid atrial pacing before and immediately after angioplasty in 22 patients with significant narrowing of the left anterior descending artery and 12 patients (control group) with minimal narrowing. A follow-up (6 months) study was also done in seven patients. Immediately after angioplasty the coronary flow reserve (peak GCVF during pacing/resting GCVF) was not fully restored (1.5 +/- 0.36 before angioplasty, 1.76 +/- 0.42 after angioplasty, and 2.13 +/- 0.33 in the control group). Resting coronary vascular resistance (2.4 +/- 0.9 mm Hg/ml/min) was significantly decreased after angioplasty (2.0 +/- 0.8 mm Hg/ml/min), whereas coronary vascular resistance during rapid pacing was fully restored to normal. Resting hyperemia was restored 6 months later, whereas coronary vascular resistance during pacing was unaltered. In five patients, however, slight ischemic ST-T changes were observed during rapid pacing, even after successful angioplasty associated with a decrease in the lactate extraction ratio. These results indicate that the impaired coronary flow reserve immediately after angioplasty may be attributed mainly to the temporal but significant increase in resting coronary flow, although impaired coronary vascular response to augmented myocardial oxygen demand may also be partially involved.

Aged↗
PubMed1992

Adverse effects of epinephrine in patients with advanced left ventricular dysfunction: analysis of ventriculo-arterial coupling.

We examined the response of ventriculo-arterial coupling to epinephrine in 19 patients with normal left ventricular function and with left ventricular dysfunction of various degrees using a conductance catheter. They were divided into three groups: group I, seven patients without left ventricular wall motion abnormality; group II, six patients with ejection fraction of 45-60%; group III, six patients with ejection fraction of 28-40%. Changes in the slope of the end-systolic pressure-volume relationship (end-systolic elastance), the effective arterial elastance, the ratio of effective arterial elastance to end-systolic elastance and the ventricular work efficiency during administration of two different doses of epinephrine (0.05 and 0.1 micrograms/kg/min) were compared among the three groups. At baseline there were no significant differences among the three groups in the ratio of effective arterial elastance to end-systolic elastance, or ventricular work efficiency. At the lower dose of epinephrine, the mean ratio of effective arterial elastance to end-systolic elastance decreased and the mean ventricular work efficiency increased in any groups. At the higher dose of epinephrine the mean ratio of effective arterial elastance to end-systolic elastance further decreased and the mean ventricular work efficiency further increased in groups I and II. However, the mean ratio of effective arterial elastance to end-systolic elastance did not decrease but the mean ventricular work efficiency even decreased in group III. Thus, in patients with advanced left ventricular dysfunction, even a high dose of epinephrine does not modulate the ventriculo-arterial coupling to increase ventricular work efficiency.

Aged↗
PubMed1992

Role of atrial contraction and synchrony of ventricular contraction in the optimisation of ventriculoarterial coupling in humans.

OBJECTIVE: To examine the effects of pacing modes on the interaction between the left ventricle and arterial system in humans. DESIGN: The slope of the end systolic pressure-volume relation (end systolic elastance), effective arterial elastance, the ratio of effective arterial elastance to end systolic elastance, and mechanical energy efficiency were compared under different pacing modes (atrial, atrioventricular, and ventricular). PATIENTS: Nine male patients with sick sinus syndrome who had cardiac catheterisation for diagnosis and to see whether they needed a pacemaker. INTERVENTIONS: A conductance catheter with tip-manometer was inserted into the left ventricle to obtain pressure-volume loops, and two pacing catheters were inserted into the right atrium and into the right ventricle respectively. RESULTS: End systolic elastance was lower in atrioventricular pacing than in atrial pacing, but effective arterial elastance was not significantly different. End systolic elastance was lower in ventricular pacing than in atrioventricular pacing, and effective arterial elastance was higher in ventricular pacing than in atrioventricular pacing. Consequently the ratio of effective arterial elastance to end systolic elastance was lowest in atrial pacing and highest in ventricular pacing, and mechanical energy efficiency was highest in atrial pacing and lowest in ventricular pacing. CONCLUSIONS: Atrial contraction and synchronous ventricular contraction independently optimise ventriculoarterial coupling in terms of a transfer of energy. Thus atrial pacing gives the best ventriculo-arterial coupling among these pacing modes.

Adult↗
PubMed1991

Effects of coronary angioplasty on left ventricular diastolic filling in patients with old myocardial infarction: a study with pulsed Doppler echocardiography.

To examine the effects of percutaneous transluminal coronary angioplasty (PTCA) on left ventricular diastolic filling in patients with an old myocardial infarction, transmitral flow velocity pattern was measured using pulsed Doppler echocardiography before and after PTCA for the peak early diastolic filling velocity (E) and the ratio of the early diastolic filling to peak atrial filling velocities (E/A ratio) in 73 patients with coronary artery disease. These patients were classified into three groups: 34 patients without previous myocardial infarction (no MI group), 16 patients with an old myocardial infarction in whom a non-infarct-related vessel was reperfused by PTCA (MI-1 group), and 23 patients with an old myocardial infarction in whom the infarct-related vessel was reperfused by PCTA (MI-2 group). The degree of improvement in left ventricular diastolic filling was calculated using the values before PTCA as controls. The % increases in E and E/A ratio were 20 +/- 15 and 25 +/- 19%, respectively, in the no MI group and 27 +/- 20 and 18 +/- 16%, respectively, in the MI-1 group and there was no significant difference between these groups. The % increases in E and E/A ratio in the MI-2 group were 7 +/- 19 and 6 +/- 17%, respectively, and were significantly (P less than 0.05) less than those in the no MI and MI-1 groups. An increase in E, E/A ratio or both by 20% or more was observed in 21 of the 34 (62%) patients of the no MI group, in 10 of the 16 (63%) patients of the MI-1 group and in six of the 23 (26%) patients of the MI-2 group. Thus, reperfusion of a non-infarct-related vessel in patients with an old myocardial infarction improves left ventricular diastolic filling to the same degree and with the same frequency as in patients without myocardial infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

Serial transcardiac lactate metabolism in post-reperfused stunned myocardium in evolving myocardial infarction.

To elucidate the relationship between lactate metabolism following reperfusion and restoration of left ventricular (LV) function, we assessed serial changes in transcardiac lactate metabolism following reperfusion therapy in 67 patients admitted to hospital within 6 h of the onset of acute anteroseptal myocardial infarction. Left ventriculograms taken about 30 min after reperfusion therapy revealed marked dyskinesis in the anteroapical region in all subjects. According to the regional ejection fraction (rEF), determined 4 weeks later as an index of LV function, patients were divided into 3 group: 1) Restored LV group: 28 patients with reperfusion and restored LV function (rEF greater than 30%); 2) Poor LV group: 26 patients with reperfusion but poor LV function (rEF less than 30%); 3) Failure group: 13 patients with failed reperfusion and occluded left anterior descending coronary artery. Although there was no difference in elapsed time and time to peak creatine phosphokinase (CPK) between the former 2 groups, the Restored LV group demonstrated lower peak CPK values, suggesting that these patients had less myocardial injury. Immediately after reperfusion, both groups showed transcardiac lactate production. In the Restored LV group, aerobic lactate metabolism was restored early after reperfusion (at 6 h), while in the Poor LV group prolonged anaerobic lactate metabolism was observed. These results suggest that an early restoration of aerobic metabolism might be a sign of stunned and viable myocardium, and a sustained lactate production might relate to a sustained process of myocardial injury.

Adult↗
PubMed1991

Spontaneous near disappearance of bilateral coronary artery-pulmonary artery fistulas.

Although coronary artery fistula is a relatively rare anomaly, it sometimes develops with advancing age, requiring surgical removal. We report a unique case of a patient whose bilateral coronary artery-pulmonary artery fistulas nearly disappeared in the course of four years. This case is interesting in view of recognizing one of the natural courses of this entity.

Angiography↗
PubMed1991

Coronary angioscopy: a monorail angioscope with movable guide wire.

A new angioscope was devised for easier visualization of the coronary artery. In its tip, the angioscope (Olympus) with an outer diameter of 0.8 mm had a metal lumen, through which a 0.014-in steerable guide wire passed. Using a 8F guiding catheter and a guide wire, it was introduced into the distal coronary artery. With injection of warmed saline through the guiding catheter, the coronary segments were visualized. In the attempted 70 vessels (32 left anterior descending [LAD], 10 right coronary [RCA], 28 left circumflex [LCX]) from 48 patients, 60 vessels (86%) were successfully examined. Twenty-two patients who underwent attempted examination of both LAD and LCX; both coronary arteries were visualized in 19 patients (86%). In the proximal site of the lesion, 40 patients have the diagonal branch or the obtuse marginal branch. In 34 patients (85%) the angioscope was inserted beyond these branches. In 12 very tortuous vessels, eight vessels (67%) were examined. In conclusion, the new monorail coronary angioscope with movable guide wire is useful to examine the stenotic lesions of the coronary artery.

Angioplasty, Balloon, Coronary↗
PubMed1990

Coronary collaterals assessed with myocardial contrast echocardiography in healed myocardial infarction.

The epicardial coronary collateral vessels are visualized with coronary angiography, but this method does not provide significant information about the myocardial perfusion supplied with the collaterals. In this study, myocardial contrast echocardiography (MCE) was performed to assess the coronary collaterals in 29 patients with old myocardial infarction. MCE was performed by intracoronary injection of 2 ml agitated amidotrizoate sodium meglumine. The peak background-subtracted gray level (PGL) in the infarct area was determined from the digitized echocardiographic images obtained before and after injection into the noninfarct and donor artery. PGL was compared with the 3-point coronary angiographic grades of collaterals. PGL in the infarct area was significantly lower in patients with poor collaterals than in patients with moderate to good collaterals (5 +/- 4 vs 18 +/- 8 U mean +/- standard deviation, p less than 0.01). PGL in the infarct area was less than 10 U in the 3 patients with severe asynergy despite the moderate to good collateral supply, suggesting that activity of the collaterals was not good enough to preserve the wall motion effectively. It is concluded that (1) the degree of MCE enhancement in the infarct area generally corresponded to the collateral grades assessed with coronary angiography, and (2) MCE may provide a measure of the collateral perfusion.

Adult↗
PubMed1990

Percutaneous transluminal coronary angioplasty using kissing balloon technique in the left main trunk.

This report describes the feasibility of the kissing balloon technique in the left main trunk in selected patients who had stenosis in the left main trunk involving bifurcation of the anterior descending artery and the circumflex artery and who also had enough blood flow to distal coronary to prevent left ventricular dysfunction during balloon occlusion or abrupt re-closure in the left main.

Aged↗