Toshiyuki Degawa

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.

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.

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.

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.

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.

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. Cathet Cardiovasc Intervent 2001;52:127–133.

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.

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.