PubMed Health⌕ Search

Biomedical subjects

T Degawa

Publications and source records attributed to T Degawa.

At least 19 recordsLinked to original sources
PubMed2001

Validation of a novel wire-type intravascular ultrasound imaging catheter.

Intravascular ultrasound can be used to characterize atherosclerotic plaques in arteries. This report describes the results of in vitro experiments with a novel wire-type intravascular ultrasound-imaging catheter developed in our laboratory. The ultrasound catheter comprises a 30-MHz transducer mounted on the tip of a wire-type catheter. The outer diameter of the catheter at the distal acoustic site was 0.025". Dimensional measurements of arteries obtained at the time of autopsy were acquired by intravascular ultrasound and direct planimetry. The luminal CSA (cross-sectional area), vessel CSA, and intima-media thickness for arterial samples (n = 22) acquired by ultrasound images and histopathologic microsections correlated closely (r = 0.99, 0.97, and 0.99, respectively). The histopathologic lumen CSA, vessel CSA, and intima-media thickness were less than those of corresponding ultrasound images in 43 of 54 samples (80%), 43 of 54 samples (80%), and 62 of 62 samples (80%), respectively. Intraobserver and interobserver variances of the luminal CSA vessel CSA and intima-media thickness by ultrasound images were excellence. This novel wire-type intravascular imaging catheter provides accurate vessel measurements and plaque thickness. Furthermore, this intravascular imaging catheter can be used in coronary arteries to assess the morphology of small distal coronary arteries.

Aged↗
PubMed2000

Coronary flow velocity immediately after primary coronary stenting as a predictor of ventricular wall motion recovery in acute myocardial infarction.

OBJECTIVES: The purpose of this study was to examine the relationship between the pattern of coronary blood flow velocity immediately after successful primary stenting and the recovery of left ventricular (LV) wall motion in patients with acute myocardial infarction (AMI). BACKGROUND: It is difficult to predict the recovery of LV wall motion immediately after direct angioplasty in AMI. Recent reports indicate that dysfunctional coronary microcirculation is an important determinant of prognosis for AMI patients after successful reperfusion. METHODS: We measured left anterior descending coronary flow velocity variables using a Doppler guide wire immediately after successful primary stenting in 31 patients with their first anterior AMI. The patients were divided into two groups: those with and those without early systolic reverse flow (ESRF). Changes in LV regional wall motion (RWM) and ejection fraction (EF) at admission and at discharge were compared between the two groups. Coronary flow velocity variables immediately after primary stenting were compared with changes in left ventriculographic indexes. RESULTS: The change in RWM was significantly greater in the non-ESRF group than it was in the ESRF group (0.9 +/- 0.7 vs. -0.1 +/- 0.3 standard deviation/chord, respectively, p < 0.001). The change in EF was also significantly greater in the non-ESRF group than it was in the ESRF group (10 +/- 10 vs. 1 +/- 6%, respectively, p < 0.05). In the non-ESRF group (diastolic to systolic velocity ratio [DSVR] <3.0), the DSVR correlated positively with the change in RWM (r = 0.60, p < 0.005, n = 24) and the change in EF (r = 0.52, p < 0.01). CONCLUSIONS: The coronary flow velocity pattern measured immediately after successful primary stenting is predictive of the recovery of regional and global LV function in patients with AMI.

Aged↗
PubMed1999

Intracoronary surface changes after Palmaz-Schatz stent implantation: serial observations with coronary angioscopy.

BACKGROUND: The objective of this study was to evaluate the appearance of the intraluminal surface after Palmaz-Schatz stent implantation by using coronary angioscopy. METHODS AND RESULTS: Coronary angioscopy was performed immediately after stenting and at 1, 3, and 6 months later in 43 patients with 45 lesions. The presence or absence of red thrombus and/or dissection and the extent of neointimal coverage of the stent struts were analyzed. Immediately after stenting, red thrombus and dissection were observed in 9 (41%) and 12 (56%) of 22 lesions, respectively, and these rates decreased with time. Complete coverage of the stent struts by smooth white neointima was observed in 55% of 11 lesions at 1 month and in 80% of 21 lesions at 3 months. However, incomplete neointimal coverage was seen in 3 lesions at both 3 and 6 months. CONCLUSIONS: In human coronary arteries, neointimal coverage of an implanted Palmaz-Schatz stent may take as long as 6 months or more.

Angina Pectoris↗
PubMed1998

The pattern of alteration in flow velocity in the recanalized artery is related to left ventricular recovery in patients with acute infarction and successful direct balloon angioplasty.

OBJECTIVES: We evaluated the relationship between alterations in coronary flow velocity during the acute phase of acute myocardial infarction (AMI) and the recovery of left ventricular wall motion in patients who underwent successful primary angioplasty. BACKGROUND: The status of the coronary microcirculation is the major determinant of the prognosis of patients who have had successful reperfusion after AMI. Animal studies have shown that dynamic changes in regional flow are associated with the extent of infarction. Evaluation of alterations in coronary flow velocity in infarcted arteries may provide information about microcirculatory damage. METHODS: Flow velocity of the distal anterior descending artery was continuously monitored with the use of a Doppler guide wire immediately after recanalization for 18 +/- 4 h in 19 patients who underwent successful primary angioplasty after anterior AMI. Subjects were divided into two groups on the basis of the time course of alterations in average peak velocity (APV). Group D consisted of patients who had progressive decreases in APV through the next day (n = 9), and Group I comprised patients with an increase in APV after a transient decline (n = 10). Ejection fraction (EF) and regional wall motion (RWM) were assessed by left ventriculography performed on admission and at discharge. RESULTS: The APV at the end of monitoring was greater in group I than in group D. In group I, EF and RWM were significantly improved at discharge. The change in EF was greater in group I than in group D (17 +/- 9% vs. 4 +/- 9%, p = 0.007), as was the change in RWM (0.96 +/- 0.23 vs. 0.13 +/- 0.36 SD/chord, p < 0.0001). CONCLUSIONS: The alteration in flow velocity in recanalized infarcted arteries is related to left ventricular recovery. A progressive decrease in velocity after angioplasty implies no reflow, which is associated with a poor recovery of left ventricular function. Reperfusion injury may account in part for this phenomenon.

Aged↗
PubMed1998

[The prevention and treatment for restenosis in coronary angioplasty].

Since the invention of Gruentzig AR in 1977, percutaneous transluminal coronary angioplasty (PTCA) has become a widely accepted therapeutic modality for the treatment of patients with ischemic heart disease (IHD). Restenosis which occurs within six months is a major problem of PTCA. Several clinical trials of pharmacological regimen have failed to show significant improvements in restenosis. Palmaz-Schatz stent could improve in restenosis. STRESS and BENESTENT DCA also could improve in restenosis when aggressive debulking was succeeded (BOAT and OARS). The recent IVUS studies have demonstrated that vessel remodeling (vessel shrinking) was the major factor of restenosis. Stent contributes to the prevention of the vessel shrinking, which leads to the improvement in restenosis. However, the rapid increase in stent implantation rates with widening indications cancels the beneficial effect of stent.

Angioplasty, Balloon, Coronary↗
PubMed1997

Prognostic value of slow resolution of ST-segment elevation following successful direct percutaneous transluminal coronary angioplasty for recovery of left ventricular function.

Our objective was to investigate the significance of the slow resolution of ST-segment elevation following a successful direct percutaneous transluminal coronary angioplasty (PTCA). ST-segment elevations were calculated from electrocardiograms recorded before PTCA and 1 hour after reperfusion. Forty-nine patients experiencing their first anterior acute myocardial infarction and who had undergone direct PTCA were classified into 3 groups: 17 patients with rapid ST resolution (group I), 23 patients with persistent ST elevation (group II), and 9 patients with ST reelevation (group III). Left ventricular function was evaluated by using single-plane cineventriculography performed in the acute stage, at discharge, and 4 months later. Peak creatine kinase activity was significantly increased: group III (4,046 +/- 634 IU), group II (3,336 +/- 772 IU), and group I (2,410 +/- 994 IU); p <0.05. Ejection fraction and regional wall motion in the acute stage were identical in each group. However, they were significantly higher in group I (67 +/- 6%, -1.01 +/- 0.30), followed by group II (56 +/- 6%, -1.90 +/- 0.41) and group III (38 +/- 7%, -2.79 +/- 0.46); p <0.01 4 months later. Multiple regression analysis revealed that the ST resolution was the only significant variable that indicated the recovery of regional wall motion. A good linear correlation was documented between the ST resolution and the recovery of regional wall motion. We concluded that a slow ST resolution after successful direct PTCA is a negative predictor of recovery of left ventricular function, especially when ST reelevation is evident.

Aged↗
PubMed1996

Safety and feasibility of continuous monitoring of coronary flow velocity in acute myocardial infarction by Doppler guide wire.

We investigated the safety and limitations of the Doppler guide wire for continuous monitoring of coronary flow velocity outside the catheterization laboratory in 17 patients with acute myocardial infarction. After direct angioplasty, patients were taken to the coronary care unit with the Doppler guide wire positioned within the artery. Flow velocity was continuously monitored. Heparin was titrated to an active clotting time > 200 seconds. Clinical outcome and angiographic analyses were evaluated. Flow velocity monitoring was conducted with an 88.2% success rate and lasted for 16 +/- 5 hours. Monitoring failed in 2 of the 4 right coronary artery cases. Small amounts of thrombus were seen to adhere to the Doppler guide wire at the end of monitoring. No complications were related to the procedure. No deterioration of angiographic findings was observed. This preliminary study confirmed the safety of the Doppler guide wire for continuous monitoring of coronary flow in patients with acute myocardial infarction.

Aged↗
PubMed1996

Distal coronary flow velocity immediately after direct angioplasty for acute myocardial infarction.

To evaluate coronary flow dynamics after direct angioplasty and to define the determinants of flow-velocity variables in the infarct artery, we measured coronary flow velocity in 36 infarct arteries and 64 normal coronary arteries by using a Doppler guide wire. Flow-velocity variables in the infarct arteries did not return to normal even after successful direct angioplasty, and phasic coronary flow in infarct arteries varied considerably. Normal phasic flow was calculated as the ratio of diastolic to systolic flow ratio (DSVR) of greater than or equal to mean DSVR - 1 SD in normal coronary arteries. Infarct-related arteries were divided into two groups: normal DSVR (n = 28) and low DSVR (n = 8). Reduced diastolic peak velocity with a relative preservation of systolic velocity contributed to a low DSVR flow. Angiographic slow flow and late recanalization were significantly related to low DSVR flow. Thus the extent of disturbed microcirculation can be evaluated by assessing phasic flow after direct angioplasty for acute infarction.

Aged↗
PubMed1996

[Evaluation of coronary arterial remodeling using intravascular ultrasound imaging].

Previous pathological studies demonstrated that the atherosclerotic coronary artery enlarges in response to developing atherosclerotic plaque. To clarify this phenomenon of coronary arterial remodeling, 24 segments of the left anterior descending artery were studied with intravascular ultrasound imaging. The luminal area and vessel area (area bounded by the echolucent zone) were measured by planimetry, and the percentage plaque area was calculated. Vessel area was correlated with plaque area (y = 12.3 + 0.72, r = 0.54, p < 0.001). When the 24 coronary segments were divided into two categories according to the percentage plaque area, there was no correlation between plaque area and lumen area in the coronary segment with less than 40% plaque area (n = 14, r = 0.20, p = NS) or less than 30% plaque area (n = 9, r = 0.18, p = NS). However, there was a correlation between plaque area and lumen area in the coronary segments with greater than 40% plaque area (n = 10, y = 22.1-0.27x, r = -0.82, p < 0.01). The correlation was somewhat better in cases with greater than 30% plaque area (n = 15, y = 22.5-0.28x, r = -0.89, p < 0.0001). Intravascular ultrasound imaging demonstrates the phenomenon of coronary arterial remodeling in vivo, which indicates that human coronary artery enlarges in response to increasing plaque area until the plaque occupies 30% of the vessel area. However, if the plaque occupies more than 30%, an increase in plaque area leads to a decrease in lumen area. Therefore, the phenomenon of coronary arterial remodeling is a compensatory mechanism to prevent luminal narrowing in the early stage of human coronary atherosclerosis.

Coronary Angiography↗
PubMed1994

Angiographic follow-up of patients after transluminal coronary extraction atherectomy.

The transluminal coronary extraction-endarterectomy catheter (TEC) consists of a torquing tube with a distal, conical rotating blade. We successfully treated 26 patients (27 lesions) using this catheter with adjunctive balloon angioplasty. Twenty-five patients (26 lesions) had serial angiography before, 1 day after, and 3 months after the procedure. All 17 patients without restenosis 3 months after the procedure had angiography at 6 months. Restenosis, defined as > 50% diameter stenosis, was noted in nine lesions at 3 months (early restenosis) and in five lesions at 6 months (late restenosis). Between vessels with and without early restenosis, the percentage of diameter stenosis seen 1 day after the procedure and the luminal diameter were significantly different (38% +/- 14% vs 22% +/- 12%, respectively, p < 0.01; 2.3 vs 2.9 mm, p < 0.01, respectively). However, between vessels with and without late restenosis, these variables were not significantly different. The overall restenosis rate was 54% (native vessels 50%; grafts 80%). This observational study suggests that very early diameter narrowing seen 1 day after the procedure has greater contribution to early restenosis than to late restenosis after successful TEC atherectomy with adjunctive balloon angioplasty.

Aged↗
PubMed1993

[Evaluation of left ventricular systolic function by pulsed Doppler echocardiography in patients with acute myocardial infarction].

Left ventricular systolic function in patients with acute myocardial infarction was assessed by Doppler echocardiographic measurement of left ventricular ejection flow velocity and maximum acceleration in 20 patients with initial acute anteroseptal myocardial infarction (group A) and 15 age-matched normal subjects. All patients underwent emergency reperfusion therapy by direct percutaneous transluminal coronary angioplasty (direct PTCA). Pulsed Doppler echocardiograms were obtained from sample volume immediately below the aortic valve in the apical long-axis view. Three parameters, peak velocity, ratio of acceleration time to ejection time (AT/ET) and maximum acceleration, were measured by the Doppler analysis program. Changes in the 3 parameters from the day of admission to the 3rd post-admission day were also observed in 15 patients. Although no significant difference was observed in AT/ET in the 2 groups, peak velocity and maximum acceleration in the patient group were significantly lower than those in the normal group (peak velocity: 90.8 +/- 13.1 vs 99.4 +/- 9.7 cm/sec, p < 0.05, maximum acceleration: 2,692.4 +/- 604.5 vs 3,410.2 +/- 712.5 cm/sec2, p < 0.01, respectively). Between the admission and 3rd day, peak velocity and AT/ET did not change significantly, but maximum acceleration increased significantly (2,720.5 +/- 676.7, 1st day vs 3,313.9 +/- 947.5 cm/sec2, 3rd day, p < 0.05). These results indicate that the maximum acceleration measured by pulsed Doppler echocardiography is useful for assessing global left ventricular systolic function in acute myocardial infarction. Direct PTCA results in improved ventricular systolic function on the 3rd post-operative day.

Adult↗
PubMed1991

[Prediction of severity of coronary artery disease by treadmill exercise testing].

Coronary angiography was performed in 250 patients with a significant ischemic ST segment change detected by symptom-limited maximum treadmill exercise testing, and relationship between anatomical severity of coronary artery disease and parameters in exercise testing was studied. The age of the patients ranged from 34 to 76 years (188 men, 62 women). One-vessel disease (1VD) was presented in 82 patients, two-vessel disease (2VD) in 42, three-vessel disease or left main coronary disease (3VD) in 26, and no significant stenosis was presented in 100 subjects (Normal). Functional aerobic impairement (FAI) was evaluated in each group as a parameter of exercise capacity, myocardial aerobic impairment (MAI) and heart rate impairment (HRI) were also evaluated as a parameter of maximum myocardial oxygen requirements and maximum heart rate, respectively. Using these parameters, discriminant analysis was performed to compare the group with significant coronary artery disease and the Normal group. Also, to compare the group with multi-vessel disease and the group with less than 2VD. Also, the 3VD group and the group with less than 3VD. FAI, MAI and HRI were significantly different (p less than 0.0001) in each group. The discriminant formula to separate the group of significant coronary artery disease from the Normal group was Z = -1.049 + 0.02 [FAI] +0.08 [MAI] +0.03 [HRI]. According to this formula, sensitivity was 92.5% and specificity was 71.5%. The discriminant formula to separate the group with multi-vessel disease from the group with less than 2VD was Z = -4.731 + 0.07 [FAI] +0.106 [MAI] +0.02 [HRI]. According to this formula, sensitivity was 96.3% and specificity was 78.8%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Left ventricular wall motion improvement after successful coronary reperfusion therapy in acute myocardial infarction: prediction by two-dimensional echocardiography].

Two-dimensional echocardiography was performed in 21 patients with acute anterior myocardial infarction who underwent intracoronary reperfusion therapy for the infarct-related left anterior descending coronary artery. The images of left ventricular wall was subdivided into 15 segments according to Heger's classification, and the wall motion of the 6 segments corresponding to the perfusion region was visually inspected before and mean 5.9 weeks after coronary intervention. The patients were categorized in 2 groups on the basis of an increase attained in wall motion score of the 6 segments; a group of patients who improved by an increase of 2 points (14 cases) and those who did not improve, not reaching a 2-point increase (7 cases). Three parameters including wall thickness of the infarcted regions, the ratio of the interventricular septum (IVS) to the posterior wall thicknesses, and the systolic wall thickening rate of the septum measured during the acute phase were compared between the 2 groups. In the improved group, the wall thickness of the infarcted region was 9.1 +/- 1.5 mm; whereas, in the unimproved group it was significantly less (7.6 +/- 1.1 mm). The ratio of the septum to posterior wall thicknesses in the improved group (0.88 +/- 0.12) was significantly greater than that of the unimproved group (0.74 +/- 0.11). No significant difference was observed in the systolic wall thickening rate. We concluded that the measurement of wall thickness of the infarcted region in the acute phase in patients with acute anterior myocardial infarction may be useful for predicting the restoration of wall motion after intracoronary reperfusion therapy.

Aged↗
PubMed1991

[Coronary collateral vessels during the early period of acute myocardial infarction: their development].

The aim of this study was to investigate the incidence and development of coronary collateral circulations in patients with acute myocardial infarction (AMI). We categorized 165 patients with persistent 100% occlusion of the infarct-related artery into 6 groups according to the time from the onset of AMI to angiography. Group I consisted of 55 patients evaluated within 6 hours after the onset of AMI; Group II, 28 patients, between 6 and 12 hours after the onset; Group III, 12 patients, between 12 and 24 hours after the onset; Group IV, 11 patients, between 2 and 13 days after infarction; Group V, 46 patients, between 14 and 44 days after infarction; and Group VI, 13 patients, more than 45 days after infarction. Collateral vessels were applied a numerical score between 0 and 3 according to the degree of opacification of the native vessel distal to the occlusion. In 58%, 79%, 67%, 73%, 89%, and 92%, patients of Groups I to VI had evidence of collateral vessels, respectively. Well-developed collaterals were observed in 24% of Group I compared with 50%, 58%, 55%, 73% and 69% of patients in Groups II to VI, respectively. The mean coronary collateral scores were 0.9 +/- 0.1, 1.4 +/- 0.2, 1.4 +/- 0.3, 1.6 +/- 0.4, 2.0 +/- 0.2 and 2.2 +/- 0.3 for Groups I to VI, respectively. Patients with preinfarction angina had more well-developed collateral circulations than did patients without it, however, there was no significant correlation between the duration of previous angina and extent of coronary collaterals.

Adult↗
PubMed1990

[Efficacy of combined therapy using coronary reperfusion and elective percutaneous transluminal coronary angioplasty for acute myocardial infarction].

The effects of elective percutaneous transluminal coronary angioplasty (PTCA) performed one month after coronary reperfusion therapy in patients with acute myocardial infarction (AMI) were observed using exercise Tl-201 myocardial scintigraphy performed before and after PTCA. Myocardial perfusion in Tl-201 scintigraphy was significantly greater in the early (less than 4 hours) and late (4-9 hours) reperfusion groups than in the total occlusion group one month after the onset of AMI. Both reperfusion groups showed significant improvement in myocardial perfusion after elective PTCA; whereas, the total occlusion group showed no significant improvement. In the early reperfusion group, there were no significant differences in myocardial perfusion between those with well developed and those with poorly developed collateral circulations one month after the onset of AMI. However, in the late reperfusion group, myocardial perfusion was greater in those with well developed collateral circulations compared to those with poorly developed collateral circulations. The grade of myocardial perfusion in the late reperfusion group with poorly developed collateral circulations did not differ significantly from that of the total occlusion group. There was significant improvement of myocardial perfusion in the early and late reperfusion groups with well developed collateral circulations after elective PTCA; whereas, no significant improvement was observed in the late reperfusion group with poorly developed collateral circulations. These findings indicate that the time interval from the onset of AMI to reperfusion and the grade of development of collateral circulations are the major determinants of myocardial perfusion after elective PTCA and after reperfusion therapy.

Adult↗