Intracoronary electrocardiogram for early detection of myocardial viability during coronary angioplasty in acute myocardial infarction.

PURPOSE: The clinical value of the intracoronary electrocardiogram (ECG) for detecting myocardial viability in acute myocardial infarction was evaluated by thallium-201 scintigraphy and left ventriculogram at the chronic stage. METHODS: Intracoronary ECGs, recorded from the tip of a guidewire during emergency coronary angioplasty, were obtained in 65 patients with reperfused anterior myocardial infarction. Further ST segment elevation of greater than 0.2 mV detected during the balloon inflation was taken as significant. The left ventricular segmental shortening was measured from left ventriculograms recorded at acute and chronic stages. The infarct area was defined as viable when a thallium uptake of more than 50% was detected on thallium-201 myocardial scintigraphy at the chronic stage. RESULTS: During emergency coronary angioplasty, significant ST segment elevation was noted in 45 patients (Group A); however, the ST segment was not significantly elevated in the other 20 patients (Group B). The infarct area of 42 patients in Group A and three patients in Group B was viable on scintigraphy. Improvement left ventricular wall motion of the infarct area was observed in 39 of the 42 patients in Group A and the three patients in Group B. Therefore, intracoronary ECG can predict reversible dysfunction with excellent sensitivity (92.9%) and specificity (73.9%). CONCLUSIONS: The myocardium within an infarct area can be regarded as viable when a further ST segment elevation occurs on intracoronary ECG during emergency coronary angioplasty. It is useful, therefore, to monitor the intracoronary ECG during coronary angioplasty balloon inflation to assess the myocardial viability of the infarct area.

Intravascular ultrasound imaging before and after angioplasty for stenosis of arteriovenous fistulae in haemodialysis patients.

BACKGROUND: Complications of haemodialysis vascular access have emerged as a major cause of patient morbidity. Intravascular ultrasound imaging is a new technical modality providing visualization of the vessel lumen and wall structure in a cross-sectional fashion. Percutaneous transluminal angioplasty has long been used in the treatment of stenoses of arteriovenous fistulae. However, there is no detailed quantitative information on the stenotic lesion and the morphological change by angioplasty. METHODS: Intravascular ultrasound studies were performed in 40 haemodialysis patients with 63 stenoses in arteriovenous fistulae who had percutaneous transluminal angioplasty. The patients were qualitatively and quantitatively evaluated for echogenic patterns and morphological changes before and after angioplasty. RESULTS: Morphological plaque features in stenotic lesions were classified as 37 soft (58%), five hard (8%), 20 mixed (32%), and one calcified sites. Plaque fractures after angioplasty were detected in 45/63 (71%) instances. The lumen cross-sectional area was found to be dilated approximately threefold (from 3.8+/-2.4 to 11.1+/-4.5 mm(2)) and the external elastic membrane cross-sectional area was dilated approximately twofold (from 11.1+/-5.3 to 19.8+/-8.1 mm(2)) after angioplasty. CONCLUSION: These results indicate that intravascular ultrasound allows both qualitative and quantitative assessments of arteriovenous fistulae in haemodialysis patients. The results further suggest that the mechanism of expansion of arteriovenous fistulae stenoses by percutaneous transluminal angioplasty involves stretching of the vessel wall as well as plaque fractures.

[Role of intravascular ultrasound imaging for assessing pathophysiology of coronary artery disease].

It has been nine years since intravascular ultrasound imaging(IVUS) was for the first time performed in Japan at our hospital. During this period, the progress of catheter technology brought about many improvements in catheter design and image quality. Also clinical utility of IVUS has been widely recognized with accumulation of clinical experiences. The most important feature of this method is the capability of both quantitative and qualitative analyses of the atheroma. IVUS has mainly been used to help guide procedures during catheter interventions and has provided information about the mechanisms of dilatation and restenosis. Recently, the ability of IVUS in diagnosing morphologic changes such as compensatory enlargement, vessel shrinkage and plaque rupture has much attention. IVUS should enhance our understanding of the pathophysiology of coronary artery disease.

A C2077T polymorphism of the type B human natriuretic peptide receptor gene is not associated with myocardial infarction.

INTRODUCTION: We examined previously the genomic structure of the human natriuretic peptide receptor type B (hNPRB) gene and reported a C2077T polymorphism located in exon 11 of the gene. We now have studied the C2077T polymorphism in myocardial infarction [MI] patients and non-MI [control] subjects to evaluate the value of this polymorphism as a marker for MI. MATERIAL AND METHODS: 302 subjects (163 MI patients and 139 non-MI age-matched control subjects) were studied. PCR-restriction fragment length polymorphism analysis (PCR-RFLP) was developed to detect the C2077T transition. RESULTS: The distribution of C2077T polymorphism genotypes in the MI patients (CC:CT:TT, 47.2%:41.1%:11.7%) was not significantly different from that in the control patients (CC:CT:TT, 53.2%:40.3%:6.5%) (chi 2 = 2.73, p = NS). Allele frequencies of the C2077T polymorphism were f(C/T) 68.2%/31.8% in the MI group and 73.4%/26.6% in the control group. However, no association was found between this polymorphism and clinical diagnosis of MI. CONCLUSION: Our data indicate that the C2077T polymorphism is not a useful marker of the relation between the hNPRB gene and MI in the Japanese and variations of the hNPRB gene that may be in linkage disequilibrium with this polymorphism do not play a causative role in MI.

[Conservative management in patients with acute coronary syndrome].

Plaque rupture has been thought to cause acute coronary syndrome. To manage the patients with unstable angina, it is necessary to understand the patients' pathophysiology. Based on the classification of unstable angina, initial medical treatment including aspirin and oral isosorbide dinitrate should be started immediately after admission. Ca antagonist and beta-blocking agent should be added according to the symptoms. If ischemic symptoms continue after administration of those oral medical treatments, intravenous nitroglycerin and heparin should be started. K channel opener (nicorandil) may be effective to stabilize the symptom. However, high-risk patients should immediately receive coronary angiography to decide further medical or interventional therapy.

Clinical utility of negative contrast intravascular ultrasound to evaluate plaque morphology before and after coronary interventions.

Although intravascular ultrasound (IVUS) is used for evaluation of plaque volume and lumen size as well as detection of vessel wall structures after catheter-based interventions, differentiation between the lumen and plaque structures can be difficult. This study attempted to evaluate the efficacy of negative contrast IVUS imaging for assessment of vessel wall morphology after coronary interventions. IVUS studies were performed in 67 lesions in 66 patients before and after coronary interventions. After the baseline ultrasound imaging run, warm 5% glucose solution was injected manually through the guiding catheter into the coronary artery to washout blood from the lumen to avoid speckled reflections from red blood cells (negative contrast). Quantitative measurements were obtained and plaque morphology was assessed for the presence and extent of medial dissections and intimal flaps. There was no difference in each quantitative parameter between baseline images and negative contrast images. The vessel wall boundary was clearly delineated from the lumen, which was defined as effective negative contrast in 51 of 67 lesions (76%). The baseline images revealed plaque dissection in 9 lesions (18%) and an intimal flap in 13 lesions (25%). In addition, 4 dissections (8%) and 16 intimal flaps (31%) were visualized during the infusion of negative contrast. Additional treatment was performed in 4 lesions (8%) based on the images with negative contrast. Negative contrast IVUS was more sensitive in demonstrating a plaque fracture than were baseline images. This method is useful for enhancing the diagnostic capability of IVUS imaging and may influence the decision-making process during interventional procedures.

[Evaluation of coronary flow velocity and coronary flow reserve before and after coronary angioplasty using transthoracic Doppler echocardiography and Doppler guide wire].

Evaluation of left anterior descending coronary (LAD) blood flow before and after coronary angioplasty was carried out non-invasively by ultrasonic Doppler echocardiography with a newly developed digital, high-frequency, high-resolution transthoracic ultrasonic Doppler flowmeter and a 7.5 MHz probe. The results were compared with those obtained using an intracoronary Doppler guide wire. Sixteen patients, 12 males and 4 females (mean age 57 +/- 14 years) with old myocardial infarction (8 patients) and angina pectoris (8 patients) were studied. Coronary flow reserve was compared following intravenous administration of adenosine triphosphate in 12 patients. The LAD blood flow was detected in 15 of 16 patients. There was a significant increase in the diastolic peak velocity from 22.2 +/- 10.6 to 29.4 +/- 14.6 cm/sec (mean +/- SD) and the coronary flow reserve from 1.8 +/- 0.3 to 2.8 +/- 0.6 (mean +/- SD). There was a good correlation between the data obtained using transthoracic flow measurement and intracoronary flow measurement (r = 0.61, p < 0.05). LAD blood flow can be easily detected parasternally using a digital, high frequency, high-resolution ultrasonic Doppler flowmeter. This method may be applicable for judging the efficacy of coronary angioplasty by measuring coronary flow reserve and for observing the clinical course of the patient non-invasively.

Intracoronary ST-segment alternans during coronary balloon angioplasty.

ST-segment alternans has been described in experimental coronary artery occlusion and in patients with variant angina. It is also seen during coronary angioplasty. This report describes a patient who on balloon inflation during coronary angioplasty demonstrated ST-segment alternans only on intracoronary electrocardiogram but did not on surface 12 lead electrocardiogram. Hemodynamic pulsus alternans of the aortic pressure tracing was not observed during electrical alternans.

Plaque rupture as a cause of apparent coronary aneurysm formation following directional coronary atherectomy.

Late coronary aneurysm formation was observed following treatment by directional coronary atherectomy. Intravascular ultrasound disclosed that the mechanism involved was plaque rupture. The cause of coronary aneurysm may be multifactorial after coronary interventions. Intravascular ultrasound imaging is useful for understanding the pathologic mechanism of coronary aneurysm production.

Assessment of plaque rupture by intravascular ultrasound.

To investigate the mechanism of plaque rupture, we carried out morphologic and quantitative assessments of ruptured plaque with a 30-MHz intravascular ultrasound catheter before coronary intervention. Plaque rupture, defined as an echolucent intraplaque area communicating with arterial lumen, was noted in all of 22 patients with coronary artery disease examined in the study. The plaque was eccentric in 16 patients (73%) and in 10 of these 16 patients there was a tear at the margin of the plaque (63%). Calcification was noted in only 6 patients (22%). Plaque area ranged from 8.7 to 44.1 mm2. The ruptured area ranged widely, from 1.0 to 14.0 mm2, and the percent ruptured area also ranged widely, from 3.9% to 50.9%. Fibrous cap was recognized in 20 patients. The thickness of the fibrous cap ranged from 0.1 to 0.6 mm (mean, 0.36 mm) and thinning of the fibrous cap was noted in 16 patients (80%). From these results, we conclude that intravascular ultrasound can provide detailed observations of plaque rupture consistent with pathologic studies. Accordingly, it is a suitable method for evaluation of plaque rupture in vivo. Plaque weakness, due to the presence of atheromatous core, thin fibrous cap, and no calcification, seems to be the major determinant of plaque rupture. In addition, the great variation in cap thickness and ruptured area suggests the role of other triggers, such as mechanical and hemodynamic stress, in plaque rupture.

Antiischemic effects of nicorandil during coronary angioplasty in humans.

The present study was undertaken on 10 patients with angina undergoing percutaneous transluminal coronary angioplasty. The angioplasty procedure consisted of two successive 30-second balloon inflations at 5 minute intervals. After the first inflation, nicorandil (0.1 mg/kg) was given intravenously over a 2-minute period. The second inflation was then performed 3 minutes after the completion of drug administration. Myocardial ischemia was measured as the magnitude of ST-segment elevation on the intracoronary electrocardiogram (intracoronary ECG) recorded from the guidewire. Nicorandil significantly reduced the magnitude of ST-segment elevation. Nicorandil did not change the heart rate-blood pressure product, nor the oxygen saturation of the blood sampled from the great cardiac vein, nor the velocity of coronary blood flow in those patients with no evidence of collaterals. These results favor the conclusion that nicorandil prolongs the intrinsic ability of cardiac myocyte to withstand oxygen deprivation. This salutary effect is possibly due to a direct cellular mechanism because nicorandil did not modify the peripheral and coronary hemodynamic parameters that govern myocardial oxygen consumption.

Intravascular ultrasound imaging after excimer laser angioplasty.

To help elucidate the mechanism of excimer laser coronary angioplasty (ELCA), intravascular ultrasound (IVUS) imaging was performed in 19 of 29 patients who were treated with ELCA. The results were compared with a non-randomized control group of 18 patients who had IVUS studies both before and after PTCA alone. After ELCA alone, lumen diameter (1.9 x 1.7 mm) and lumen cross-sectional area (CSA) (2.9 mm2) by IVUS were not significantly different from baseline values in the patients before PTCA alone (2.1 x 1.8 mm, 3.2 mm2). After balloon dilatation in the laser treated group, lumen diameter (2.5 x 2.1 mm) and lumen CSA (4.9 mm2) were significantly greater than those post ELCA alone. However, there was no difference in lumen CSA or atheroma CSA in the group treated with excimer laser plus balloon dilatation vs. these measurements in the group treated with PTCA alone. ELCA does not ablate a large amount of atheroma (9% reduction) but creates a pathway to permit easier passage of a PTCA balloon. These quantitative and morphologic results may help explain why the restenosis rate with ELCA is similar to PTCA alone.

Intravascular ultrasound imaging in human peripheral and coronary arteries in vivo.

To determine the feasibility of intravascular ultrasound imaging in vivo, a miniaturized high frequency transducer catheter was introduced into human peripheral (n = 10) and coronary (n = 4) arteries. Cross-sectional ultrasound images were obtained from iliofemoral arteries in 10 patients using a 20 MHz transducer catheter (1.2 mm in diameter) and from coronary arteries in 4 patients using a 30 MHz transducer catheter 5 French size (Fr) following successful coronary angioplasty. Ultrasound images obtained from peripheral arteries showed a three-layered appearance (echo-reflective intima, echo-lucent media and echo-reflective adventitia) in the normal arteries. In diseased arteries, the location, amount and extent of atheromatous plaque were clearly documented. The arterial diameters measured by ultrasound closely correlated with the measurements by angiography (r = 0.91) in the peripheral arteries. Coronary angiograms obtained following balloon angioplasty revealed smooth edges at the dilatation sites without significant narrowing in all patients. However, a significant amount of residual atheromatous plaque was clearly observed on the ultrasound images at the previously dilated sites. Coronary dissection, which was identified as an echo-lucent area behind the plaque, was noted in 2 patients. Ultrasound images also revealed the presence of calcium in the plaque which was unrecognized on the angiograms in 3 patients. In addition, direct measurement of the lumen cross-sectional area was possible on the ultrasound images.(ABSTRACT TRUNCATED AT 250 WORDS)

Morphological effects of coronary balloon angioplasty in vivo assessed by intravascular ultrasound imaging.

BACKGROUND: Histological examination of the effects of balloon angioplasty have been described from in vitro experiments and a limited number of pathologic specimens. Intravascular ultrasound imaging permits real time cross-sectional observation of the effect of balloon dilation on the atherosclerotic plaque in vivo. METHODS AND RESULTS: The morphological effects of coronary angioplasty were visualized at 66 lesions in 47 patients immediately after balloon dilatation with an intravascular ultrasound imaging catheter. Cross-sectional images were obtained at 30 frames per second as the catheter passed along the length of the artery. Quantitative and qualitative assessments of the dilated atherosclerotic plaque were made from the angiograms and the ultrasound images. Six morphological patterns after angioplasty were appreciated by ultrasound imaging. Type A consists of a linear, partial tear of the plaque from the lumen toward the media (seven lesions); Type B is defined by a split in the plaque that extends to the media (12 lesions); Type C demonstrates a dissection behind the plaque that subtends an arc of up to 180 degrees around the circumference (18 lesions); Type D was a more extensive dissection that encompasses an arc of more than 180 degrees (four lesions); and Type E may be present in either concentric (Type E1, 14 lesions) or eccentric (Type E2, 11 lesions) plaque and is defined as an ultrasound study without any evidence of a fracture or a dissection in the plaque. There was a large amount of residual atheroma in each type of morphology (7.8 +/- 2.9 mm2, 61.6 +/- 15.4% of cross-sectional area); there was no difference, however, in lumen or atheroma cross-sectional area among these six patterns. There was a good correlation between ultrasound and angiography for the recognition of a dissection. Calcification was seen in only 14% of lesions on angiography, whereas most lesions (83%) revealed calcification on ultrasound imaging. As determined by intravascular ultrasound, calcified plaque was more likely to fracture in response to balloon dilatation than noncalcified plaque (p less than 0.01). Thirteen of 66 lesions (20%) developed clinical and angiographic restenosis. Restenosis was more likely to occur when the original dilatation left a concentric plaque without a fracture or dissection (Type E1, 50% incidence) compared with a mean restenosis rate of 12% in the remaining morphological patterns (p = 0.053). CONCLUSIONS: Intravascular ultrasound provides a more complete quantitative and qualitative description of plaque geometry and composition than angiography after balloon angioplasty. In addition, intravascular ultrasound identified a subset of atherosclerotic plaque that has a higher incidence of restenosis. This information could be used prospectively to consider other therapeutic options in this subset. Intravascular ultrasound provides a method to describe the effects of angioplasty that will be useful in comparing future coronary intervention studies.

Laser-assisted versus mechanical recanalization of femoral arterial occlusions.

A randomized clinical trial was performed to test the hypothesis that a laser-heated probe is superior to standard techniques to reopen occluded femoral arteries. Twenty patients were treated with a standard guidewire and balloon dilation method. In a second group of 20 patients, the laser probe was initially used as a nonheated mechanical device. If the probe was unsuccessful in mechanically reopening the artery, an Argon laser was activated to heat the probe. The mean length of occlusion was 15.9 +/- 10.3 cm. The success rate for the laser probe was 15 of 20 (75%), which was not significantly different from the standard method, 19 of 20 (95%). Most of the success in the laser-probe group was due to the probe's mechanical properties. The laser probe was successful as a cold, mechanical device in 13 of 15 (87%) arteries. It was necessary to heat the probe in 5 patients. When heated, the laser probe assisted recanalization in 2 but perforated the artery in 3 cases. The results of this randomized trial do not support the hypotheses behind the use of the thermal laser probe. The laser probe functions primarily as a mechanical device. The thermal activation does not significantly improve the success rate without increasing the risk of perforation. This small additional benefit does not justify the large cost of current thermal laser devices. This controlled study also demonstrates a higher success rate in long occlusions than previous reports of mechanical balloon recanalization. This is due to a combination approach of retrograde and anterograde probing of the occluded segment.

Unrecognized stenosis by angiography documented by intravascular ultrasound imaging.

This report documents how intravascular ultrasound imaging was used to diagnose a short "napkin-ring" stenosis that was missed by coronary angiography. Intravascular ultrasound revealed a lumen of 2.6 x 2.5 mm in diameter and 5.0 mm2 in cross-sectional area, with a residual atheroma that occluded 63% of available cross-sectional area at the stenosis.

Sudden appearance of coronary thrombus observed by angiography--a case report.

A sudden coronary thrombus formation was documented by chance during cardiac catheterization in a patient with postinfarction angina. The thrombus was successfully treated with intravenous urokinase and heparin infusions, and thereafter, coronary angioplasty was performed without any complication.