Taro Tsunoda

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.

Chronic stent recoil plays an important role in restenosis of the right coronary ostium.

ObjectiveThe efficacy of coronary stenting of aorto-ostial atherosclerotic lesions is still unclear. We investigated the frequency and mechanism of stent restenosis at this particular lesion. MethodsFifty-five consecutive patients with 64 native aorto-ostial lesions in the right coronary artery (RCA, n=38) and the left main trunk (LM, n=26) were treated by conventional stenting. Determinants of angiographic restenosis were established. The mechanism of stent restenosis was evaluated using post-stenting and follow-up intravascular ultrasound (IVUS) findings. ResultsRestenosis was more frequent in the RCA than in the LM (50% compared with 19%, P<0.03) and determinants included diabetes mellitus (63% compared with 21%, P<0.03), calcium deposition (58% compared with 5%, P<0.003), smaller stent cross-sectional area (SA) (as demonstrated by post-stenting IVUS studies, 8.1±1.4 mm2 compared with 10.2±2.2 mm2, P<0.01), larger plaque burden (64±6% compared with 57±8%, P<0.03) and less circular expansion at the aorto-coronary junction. Serial IVUS examination was performed in 11 patients with restenosis of the right coronary ostium. The mean reduction in the SA was 21% at the aorto-coronary junction (6.4±1.9 mm2, P<0.003), whereas the SA at the distal edge was unchanged. Thirty-three per cent of late luminal loss was due to chronic stent recoil. ConclusionThese findings suggest that stenosis of the right coronary ostium is a high-risk lesion for stent restenosis. In addition to excessive intimal growth, chronic stent recoil might be an important etiologic factor at this particular location.

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.

Ultrasound attenuation behind coronary atheroma without calcification: Mechanism revealed by autopsy

When performing intravascular ultrasound studies, the backward echo image can show marked attenuation, although there are no calcified deposits and it may be impossible to detect the intraplaque architecture. The pathology underlying this phenomenon was investigated in autopsy specimens. We hypothesize that the mechanism responsible for the attenuation involves micro‐calcification and lipid in unstable plaques causing ultrasonic wave reflection and dispersion.

Intracoronary ultrasound examinations reveal significantly more advanced coronary atherosclerosis in people with type 1 diabetes than in age- and sex-matched non-diabetic controls

Aims/hypothesis: The extent of coronary atherosclerosis is significantly more advanced in symptomatic type 1 diabetes patients than in symptomatic non-diabetic patients. Whether this difference exists between asymptomatic individuals with diabetes and controls is not documented. In vivo imaging techniques allow quantification of the difference at a preclinical stage. Methods: The degree of coronary atherosclerosis in early onset type 1 diabetes patients without symptoms of cardiovascular disease was compared with that of age- and sex-matched controls. Intracoronary ultrasound (IVUS) examinations were performed to determine the degree of atherosclerosis. The mean age of the patients was 43 years (35–58), they had a mean duration of disease of 30 (23–39) years and the diagnosis of type 1 diabetes was made at a mean age of 12.5 years. The controls were people with transplanted hearts; donors were sex- and age-matched and had a mean age of 43 (35–58) years. Results: The degree of subclinical coronary atherosclerosis was significantly more severe in type 1 diabetes patients than in controls. This was the case for all parameters measured. The mean plaque area was ≥ 40% in 71% (54/76) of diabetic arteries as opposed to 33% (25/76) of arteries from controls (p<0.0001). The mean plaque thickness was 0.59±0.38 mm vs. 0.44±0.30mm in controls (p<0.0001). The mean lumen area was 8.6±3.8mm2 in type 1 diabetes and 12.1±4.3 mm2 in controls (p<0.0001). Conclusions/interpretation: Asymptomatic individuals with type 1 diabetes have significantly more advanced sub-clinical coronary atherosclerosis than controls. Coronary atherosclerosis in type 1 diabetes develops at an early age.

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.

Percutaneous bare Z-stent implantation as an alternative to surgery for acute aortic dissection with visceral ischemia

We describe a case of Stanford type B acute aortic dissection causing visceral ischemia. An aortogram showed an hourglass‐like narrowing of the true lumen at the diaphragm with a 60 mm Hg pressure gradient. Placement of a self‐expanding metallic Z‐stent under intravascular ultrasound guidance restored blood flow to the viscera. Cathet Cardiovasc Intervent 2003;58:95–100.

Stent deformation: an experimental study of coronary ostial stenting☆

OBJECTIVES To investigate stent deformation by torsional stress after implantation at the ostium of a model coronary artery. BACKGROUND Little is known about coronary stent deformation, especially the association between stent design and deformation at the coronary ostium. Recent reports have suggested that mechanical factors are important for stent restenosis. METHODS A coronary ostium model was constructed and three different stents (Express(2), Cypher, and Tsunami, n=5 each) were implanted at the aorto-ostial junction. Differences of stent deformation were assessed after exposure to torsional stress. Intravascular ultrasound was used to measure the luminal area along each stent. Then the extent and pattern of plastic deformation were compared between the three stent types. RESULTS The Express(2) stents and Cypher stents both showed significant deformation (P<.0001 and P=.045, respectively) adjacent to the ostium, whereas only a minimal decrease of luminal area was observed with the Tsunami stent. In the central and distal parts of each stent, the decrease of luminal area was minimal and no differences were noted among the three types. Sudden fracture of a Cypher stent strut occurred during the experiment. CONCLUSION Differences of structural characteristics influence permanent plastic deformation at sites where continuous stress occurs, such as the coronary ostium. A more elastic design may show better resistance to such stress.

Coronary artery fistula with an associated aneurysm detected by 16-slice multidetector row computed tomographic angiography

We describe a case of a 60-year-old man with effort-induced angina pectoris. Coronary angiography showed an aneurysm in the proximal left anterior descending coronary artery. It was unclear whether it was a coronary artery aneurysm or a coronary fistula with an associated aneurysm. Three-dimensional reconstruction images from 16-slice multidetector row computed tomographic (MDCT) angiography showed an aneurysm that drained into the pulmonary artery. Images from 16-slice MDCT coronary angiography can be helpful in understanding complex coronary artery anatomy.

Insulin resistance and acute coronary syndrome in the young Japanese population have a strong association

There are few data regarding acute coronary syndrome (ACS) in young Japanese patients. We examined the risk factors for ACS in young Japanese patients, especially impaired glucose metabolism. From a database of 789 consecutive patients admitted to our hospital with ACS between 2000 and 2005, we compared risk factors of patients divided into two age categories: ≤45 years (group Y, n = 41) and ≥46 years (group O, n = 748). All patients in group Y were male. Overt diabetes, hypertension, and a family history of ischemic heart disease were not so important to group Y. Higher triglyceride (160.5 ± 86.0 vs 133.9 ± 75.2 mg/dl, P = 0.0296) and lower high-density lipoprotein cholesterol (43.9 ± 12.1 vs 48.7 ± 13.5 mg/dl, P = 0.027) concentrations were present in group Y. We obtained data concerning insulin resistance in 326 of 789 patients. Although the incidence of impaired glucose tolerance was similar between the groups (31% vs 31%, not significant), a higher homeostasis model assessment insulin resistance index (2.26 ± 2.03), indicating insulin resistance, was present in group Y. Insulin resistance might be correlated with the development of ACS in the young adult Japanese population.