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To assess the morphologic correlate of the presence and absence of pathologic Q waves in the electrocardiogram, 30 patients with and 17 patients without pathologic Q waves and chronic myocardial infarction (infarct age >4 months) and 15 patients without previous myocardial infarction but significant coronary artery disease (>70% diameter stenoses) were studied by gradient-echo magnetic resonance imaging (MRI). Short-axis MRI tomograms were evaluated on a segmental basis by calculating end-diastolic wall thickness and systolic wall thickening. All segments were graded transmural scar (end-diastolic wall thickness < end-diastolic wall thickness of a healthy control group [n = 21] - 2.5 SD and lack of systolic wall thickening), hypokinetic (end-diastolic wall thickness [greater than or equal to] end-diastolic wall thickness of the control group - 2.5 SD and systolic wall thickening [less than or equal to] 2 mm), or normal (end-diastolic wall thickness [greater than or equal to] end-diastolic wall thickness of the control group - 2.5 SD and systolic wall thickening >2 mm) by MRI criteria. Myocardial infarcts were defined as transmural if at least 1 segment fulfilled the MRI criteria for transmural scar. Of 30 patients with Q-wave infarction, 26 (87%) had a transmural defect, and 6 of 17 patients (35%) with non-Q-wave infarction had a transmural infarct. Segmental evaluation yielded 129 of 480 scar segments (27%) for patients with Q-wave infarction, 20 of 272 scar segments (7%) for patients with non-Q-wave infarction, and no scar segments for patients without previous myocardial infarction. The proportion of segments graded transmural scar was significantly (p

To assess the feasibility, safety and usefulness of gradient-echo magnetic resonance imaging (MRI) combined with pharmacologic stress testing for the detection of coronary artery disease, 23 patients without previous myocardial infarction but with significant stenosis (>70% diameter stenosis) of [is greater than or equal to]1 major coronary artery were selected for dipyridamole-MRI stress testing. Each patient underwent MRI at rest, and high-dose dipyridamole-MRI (0.75/kg over 10 minutes) of corresponding basal and midventricular short-axis tomograms. Additionally, these patients performed symptom-limited exercise stress tests. All short-axis tomograms were evaluated on a standardized segmental basis by grading each segment as normal, hypokinetic or dyskinetic. Dipyridamole-MRI was considered pathologic if segmental wall motion deteriorated by [is greater than or equal to]1 grade after dipyridamole. For comparison with coronary angiography, segmental wall motion gradings were related to the respective coronary artery territories in the short-axis plane. Pathologic dipyridamole-MRI was obtained in 18 of 23 (78%) patients. For 1- and 2-vessel diseases, sensitivity was 69 and 90%, respectively. Exercise stress tests were pathologic in 14 of 23 (66%) patients. For 1-and 2-vessel diseases, sensitivity of exercise stress test was 58% (7 of 12 patients) and 77% (7 of 9), respectively. Sensitivity/specificity of dipyridamole-MRI for the localization of the stenosed coronary artery was 78/100% for left anterior descending, 73/100% for left circumflex, and 88/87% for right coronary artery stenoses. It is concluded that dipyridamole-MRI is a feasible nonexercise-dependent test for detection and localization of functionally significant coronary artery disease.

The most effective treatment of severe paraquat poisoning in man is uncertain. In order to prevent pulmonary fibrosis, we employed radiotherapy of both lungs in a 23-year-old patient with severe [...]

BackgroundAlthough the use of premounted stents on a delivery balloon has almost completely eliminated the initially used hand-crimping procedure, no data are available that prove the superiority of one or the other approach on a randomized basis. Therefore, this study was designed to examine whether the use of premounted stents is comparable with the hand-crimping procedure. MethodsA total of 123 patients (64 treated with unmounted stents, 59 treated with premounted stents) were examined in a multicenter, randomized, prospective study. There were no significant differences in patient characteristics between groups. ResultsPrimary end points (acute, postinterventional [within 72 hours], and late complications related to the stenting procedure) were reached in 1 patient treated with an unmounted stent versus 2 patients with mounted stents (P= not significant). In patients with angiographic follow up (n = 84, mean follow-up period 6 ± 1 months), the total rate of restenosis was 27% (unmounted 12, mounted 11, P= not significant). Secondary end points were procedural success of stenting and maximal balloon inflation pressure needed for optimal stenting results by use of angiography. There were no differences in secondary end points for both techniques. The mean balloon pressure was 12.56 ± 2.1 atmospheres (unmounted) and 12.12 ± 1.92 atmospheres (mounted, P= not significant). ConclusionStenting with premounted devices was demonstrated to have a similar clinical and angiographic outcome as the hand-crimping approach for maximal inflation pressure, procedural success, major cardiac events, and rate of restenosis after 6 months of follow up. Thus, the more convenient use of a premounted stent provides procedural safety and efficacy comparable with a hand-crimped system. (Am Heart J 2003;145:e4.)

Background: Beside thrombolysis, percutaneous transluminal coronary angioplasty (PTCA) has become a well‐established treatment for acute myocardial infarction. However, restenosis occurs in approximately 15%‐40 % of patients. Despite a frequently occurring infarct‐related regional systolic dysfunction at rest, the identification of hemodynamically relevant restenosis seems important in terms of risk stratification, adequate treatment, and possible improvement of prognosis in these patients. This study was designed to assess the role of transesophageal dobutamine stress echocardiography and myocardial scintigraphy for identification of hemodynamically significant restenosis after PTCA for acute myocardial infarction. Methods: Multiplane transesophageal stress echocardiography (dobutamine 5, 10, 20, 30, and 40 μg/kg per min) studies and myocardial single photon emission computed tomography (SPECT) studies were performed in 40 patients, all of whom underwent PTCA in the setting of acute myocardial infarction ≥ 4 months prior to the test. Repeated coronary angiography was performed in all study patients who showed stress‐induced perfusion defects or wall‐motion abnormalities, or both. Results: Significant restenosis (≥ 50%) was angiographically found in 15 (37.5%) of 40 patients. Of these 15 patients, transesophageal dobutamine stress echocardiography identified restenosis in 12 (80%) and myocardial SPECT in 14 (93%), yielding diagnostic agreement in 70% of patients. Echocardiographic detection of restenosis was based mainly on a biphasic response to increasing doses of dobutamine. Sensitivity and specificity for identification of hemodynamically relevant restenosis in individual patients was 80% and 92%, respectively for dobutamine stress echocardiography versus 93% and 68% for myocardial SPECT. Conclusions: Both transesophageal dobutamine stress echocardiography and myocardial SPECT were highly sensitive in identifying significant restenosis after PTCA for acute myocardial infarction. Therefore, either test, as a single diagnostic tool or especially if performed together, are clinically valuable alternatives to coronary angiography for the detection of restenosis after PTCA for acute myocardial infarction.

OBJECTIVES

Abstract Stress testing is the cornerstone in the diagnosis of patients with suspected coronary artery disease (CAD). Although exercise ECG remains the primary approach for the detection of ischemia in patients with chest pain syndromes, its sensitivity and specificity is limited and exercise ECG does not provide detailed information about the localisation and extent of CAD. Stress echocardiography has been used for the detection of ischemia for more than a decade and has become an increasingly popular noninvasive method for the detection of CAD. In experienced hands wall motion analysis based on stress echocardiography has proved to be as sensitive and specific for the detection of myocardial ischemia as scintigraphic techniques. Recent technical improvements, namely the availability of ultrafast imaging sequences with a significant reduction of imaging time have initiated several studies which examined the combination of pharmacological stress and magnetic resonance imaging (MRI) for the detection of suspected CAD. The most well developed stress-MRI technique is wall motion imaging during dobutamine stress. This technique is analogous to stress echocardiography, but MRI has the inherent advantages of better resolution, higher reproducibility and true long and short axis imaging with contiguous parallel slices. However, the clinical impact of MRI for the diagnosis of CAD is still low. Further technical developments including real time imaging and a reliable automated quantitative analysis of left ventricular function are required before stress-MRI becomes a serious challenge to stressechocardiography in the clinical arena. Currently, only a few MRI facilities and physicians are dedicated to pharmacological stress testing with MRI and the future clinical impact of this promising technique will depend on its potential to provide information beyond myocardial function including, perfusion, metabolism and coronary anatomy in form of a "one-stop"-shop for the cardiac patient. Zusammenfassung Das Belastungs-EKG ist für die nicht invasive Erkennung der koronaren Herzkrankheit aufgrund seines im Vergleich zu allen anderen Methoden geringeren zeitlichen, personellen und apparativen Aufwands die diagnostische Maßnahme der ersten Wahl. Bei nicht eindeutigem Belastungs-EKG oder bei Unfähigkeit des Patienten, sich körperlich zu belasten, kommt als nächster Schritt die Anwendung klinisch etablierter Verfahren, wie Stressechokardiographie oder alternativ Myokardszintigraphie, in Betracht. Seit der ersten Beschreibung der Stressechokardiographie 1979 hat sich diese Untersuchungstechnik durch eine kontinuierliche Verbesserung von Bildqualität ("second harmonic imaging"), Auswerteverfahren (Quad-Screen-Analyse) und Aufzeichnungsmöglichkeiten (digitale Bildspeicherung) in Bezug auf Zuverlässigkeit und Durchführbarkeit ständig verbessert. Damit konnten die Indikationsstellung und das Einsatzspektrum der Stressechokardiographie in der Ischämiediagnostik unter Nutzung dynamischer und pharmakologischer Belastungsmodalitäten auf Kosten nuklearmedizinischer Verfahren erweitert werden. Trotz der offensicht-lichen Vorteile der Stressechokardiographie (keine Strahlenbelastung, relativ preiswert, beliebig wiederholbar, schnelle Verfügbarkeit) dürfen ihre Nachteile nicht übersehen werden. Wichtigster Nachteil ist die Beurteilung der stressechokardiographischen Untersuchung nach visuellen (qualitativen) Kriterien, wodurch die Reproduzierbarkeit ihrer Ergebnisse (Wandbewegungsanalyse) stark vom Training und der Erfahrung des Untersuchers abhängig ist. Selbst bei erfahrenen Untersuchern ist in Einzelfällen mit einer starken Variabilität der Befundung stressechokardiographischer Untersuchungen zu rechnen. Darüber hinaus ist trotz technischer Fortschritte bei 10 bis 15% der Patienten die Bildqualität nicht ausreichend, um zu einer sicheren Beurteilung der stressechokardiographischen Untersuchung zu kommen. Mit der Magnetresonanztomographie (MRT) steht im Gegensatz zu den nuklearmedizinischen Verfahren eine in der Kardiologie relativ neue und bisher in der Diagnostik der koronaren Herzkrankheit noch nicht etablierte Untersuchungstechnik zur Verfügung, die aber ähnlich wie die Echokardiographie eine morphologische und funktionelle Beurteilung des Herzens in Ruhe und unter Belastung erlaubt. Die hervorragende räumliche Auflösung der MRT, verbunden mit einem guten Gewebekontrast, sowie die klare Beurteilbarkeit der endo- und epikardialen Grenzen haben in den letzten zehn Jahren zu einer Reihe von Studien geführt, die basierend auf Wanddicken- und Volumenmessungen des linken Ventrikels und Bestimmung der systolischen Wanddickenzunahme in Ruhe und unter pharmakologischer Belastung die Eignung der MRT für die Ischämiediagnostik im Vergleich zu nuklearmedizinischen Verfahren und zur invasiven Diagnostik nachgewiesen haben (Tabellen 1 und 2). Trotz der hervorragenden diagnostischen Zuverlässigkeit in der Erkennung von Wandbewegungsstörungen unter Dipyridamol- und Dobutamin-Stress und in der Lokalisierung von Koronarstenosen konnte sich die MRT klinisch nicht etablieren. Dafür sind eine Reihe wirtschaftlicher (hohe Investitions- und Untersuchungskosten), logistischer (Verfügbarkeit des Gerätes und der Befunde) und technischer Gegebenheiten (zum Beispiel schwierige Patientenüberwachung, lange Untersuchungsdauer, keine On-line-Kontrolle der Wandbewegung unter Belastung) sowie die schnelle Weiterentwicklung der leicht zugänglichen Stressechokardiographie verantwortlich zu machen. Erst seit kurzem ist es durch technische Weiterentwicklung der MRT möglich, mit Hilfe ultraschneller Bildakquisition Dobutamin-Belastungsuntersuchungen in einem Zeitraum ähnlich dem der Stressechokardiographie (ca. 30 Minuten) und mit der in der Dobutamin-Stressechokardiographie üblichen Dobutamin-Dosierung (10 bis 40 μg Dobutamin/kg pro Minute und fakultativ Atropin) durchzuführen. Diese Entwicklung machte den Weg frei für die erste direkte Vergleichsstudie zwischen der Stressechokardiographie und der Stress-MRT, basierend auf einem standardisierten Dobutamin-Belastungsprotokoll (Tabelle 3). Bei identischen segmentalen Auswerteverfahren der linksventrikulären Wandbewegung für beide Untersuchungs-techniken (Abbildung 1) fand sich eine im Vergleich zur Dobutamin-Stressechokardiographie signifikant bessere Erfassung der koronaren mit der Dobutamin-MRT (Sensitivität: 88,7% vs. 74,3%; p &lt; 0,05 und Spezifität 85,7% vs. 69,8%; p &lt; 0,05). In einer weiteren Studie konnte gezeigt werden, dass die Dobutamin-MRT bei schlechter Beschallbarkeit der Patienten eine zuverlässige Alternative zu nu-klearmedizinischen Verfahren darstellt (Dobutamin-MRT vs. Dipyridamol-Thallium-201-SPECT; Sensitivität 87% vs. 90%; p = n. s.; Spezifität 86% vs. 71%; p = n. s.). Auch in Anbetracht dieser klinisch interessanten Ergebnisse und sicher zu erwartender weiterer technischer Fortschritte stellt die Stress-MRT, basierend auf einer Vielzahl logistischer und wirtschaftlicher Gesichtspunkte, zur Zeit keine Konkurrenz für die Stressechokardiographie dar (Tabelle 4). Ein breiter klinischer Einsatz der MRT in der Kardiologie ist nur dann zu erwarten, wenn über die funktionelle Diagnostik hinaus wichtige Parameter, wie Perfusion, Metabolismus und die Koronararterien, in einem Untersuchungsgang nichtinvasiv erfasst werden können. Nur wenn die MRT zukünftig das Versprechen einer integrativen Diagnostik des herzkranken Patienten, des sogenannten "One-Stop-Shop", einlösen kann, wird sie auch mit einem hoch innovativen Verfahren wie der Echokardiographie im klinischen Alltag konkurrieren können.

Breath-hold gradient-echo magnetic resonance imaging (MRI) in conjunction with pharmacologic dobutamine stress has become a practical tool to investigate patients with chest pain. The presence of high-grade coronary artery stenoses can be detected more accurately than with stress echocardiography. The main diagnostic advantage of MRI is in patients with suboptimal echocardiographic image quality. Depiction of left ventricular anatomy and function at rest and during low-dose dobutamine stress is also clinically useful for evaluating patients with severely impaired left ventricular function for the presence of residual myocardial viability. Recovery of regional and global left ventricular function can be accurately predicted by stress functional MRI. J. Magn. Reson Imaging 1999;10:667–675, 1999. © 1999 Wiley-Liss, Inc.

Objectives. We sought to assess the feasibility and accuracy of myocardial contrast echocardiography (MCE) using standard imaging approaches for the detection of perfusion defects in patients who had a myocardial infarction (MI).

OBJECTIVES

Objectives. This study was designed to assess the predictive value of myocardial viability diagnosed by dobutamine transesophageal echocardiography and fluorine (F)-18 fluorodeoxyglucose positron emission tomography for left ventricular functional recovery after revascularization in patients with chronic left ventricular dysfunction.

Objective. The value of rest technetium-99m (Tc-99m) sestamibi scintigraphy under oral nitrate medication to predict myocardial viability was examined in patients with chronic infarcts.

Objectives. This study sought to evaluate whether myocardial viability, as assessed by magnetic resonance imaging (MRI), reliably predicts postrevascularization left ventricular (LV) recovery.

Magnetic resonance techniques have only recently been employed to assess residual myocardial viability after myocardial infarction. Three approaches have been described to achieve this purpose: First, the use of signal intensity changes on spin-echo images with and without the application of contrast media to define irreversible injury to the myocardium in acute and subacute infarcts; second, measurement of metabolite concentrations within the infarct area using magnetic resonance spectroscopy, and third, quantitation of myocardial thickness and systolic wall thickening in chronic infarcts. This paper reviews the pertinent literature and compares MR techniques with other imaging techniques used in the diagnosis of myocardial viability.

Magnetic resonance imaging (MRI) has been used in conjunction with dipyridamole induced wall motion abnormalities for the noninvasive detection of coronary artery disease (CAD). To assess the clinical usefulness of dipyridamole-MRI for the localization of CAD and to evaluate the relation between dipyridamole induced wall motion abnormalities and myocardial perfusion 33 patients with severe CAD (>70% diameter reduction) underwent MRI at rest and after dipyridamole infusion (0.75 mg dipyridamole/kg over a period of 10 minutes). All patients performed exercise stress testing and 20 patients of the study group additionally had rest and exercise stress99mTc-methoxyisobutyl-isonitrile-SPECT (MIBI-SPECT). Two patients (6%) could not be evaluated due to severe motion artifacts during dipyridamole MRI.

Dobutamine pharmacological stress testing in conjunction with technetium-99m methoxyisobutylisonitrile single-photon emission tomography (MIBI SPET) may be a useful alternative to convential exercise stress MIBI SPET for the detection and localisation of coronary artery stenoses. Therefore, 35 patients with stenoses (= 50% diameter reduction) of one or more coronary arteries were selected for dobutamine MIBI SPET. Each patient underwent MIBI injection at rest and during dobutamine infusion with incremental doses (5, 10, 15 and 20 µg kg-1 min-1). A conventional exercise stress test (EST) was performed in all patients. Peak double product during steady-state dobutamine infusion (18 200 ± 4200 mmHg min-1) was lower (P = 0.0001) than during EST (21 700 ± 4900 mmHg min-1). Image quality was good in all but one patient, who had to be excluded from data analysis due to excessive hepatobiliary MIBI activity. Dobutamine-induced perfusion abnormalities were observed in 30/34 MIBI SPET studies, resulting in an overall detection rate for coronary artery disease of 88%. A pathological EST was observed in 23/34 patients (68%). The detection rate of individual coronary artery stenoses was 85% (28/33) for stenosess with a severe diameter reduction (>70%) and 50% (12/24) for stenoses with a moderate diameter reduction (= 50–70%). In particular, sensitivity and specificity for the detection of moderate and severe stenoses (= 50%) were 75%/100% for left anterior descending, 67%/95% for left circumflex and 67%/69% for right coronary artery stenoses. Dobutamine MIBI SPET is a well-tolerated, non-exercise-dependent test for detection and localisation of haemodynamically significant coronary artery stenoses. The use of dobutamine allows a stepwise increase in pharmacological stress similar to EST and is especially useful in patients who are unable to exercise.

Objectives. The aim of this study was to assess whether dobutamine transesophageal echocardiography can identify viable myocardium in patients with chronic myocardial infarction.

4. Conclusion: Despite the evaluation of different parameters of myocardial viability by PET, TEE and MRI, their positive and negative predictive accuracies are fairly comparable. Therefore, the choice of the method to date mainly depends on expertise and available resources. An accepted reference standard to assess the diagnostic accuracy of imaging techniques is the post-revascularization recovery of regional LV function. In this respect, dobutamine-MRI proved to be a reliable and clinically feasible approach in a head to head comparison with FDG-PET and dobutamine-TEE. However, there is still limited information with respect to the potential benefit of revascularization procedures in the clinically important subset of patients with viable myocardium, markedly reduced LV function and congestive heart failure. In this patient population, the advantageous features of MRI including high spatial and temporal resolution, three-dimensional capability with unlimited field of view and the capability to measure perfusion may increase the clinical impact of MRI compared to established imaging techniques. Moreover, improvement of global LV ejection fraction, alleviation of symptoms and survival are fundamental clinical end points to additionally evaluate the predictive value of MR-studies for clinical decision making in patients with left ventricular dysfunction and persisting viable myocardial tissue.

Background Cobalt chromium coronary stents are increasingly being used in percutaneous coronary interventions. There are, however, no reliable data about the characteristics of unfolding and visibility of this stent alloy in vivo. The aim of this study is to compare cobalt chromium coronary stents with conventional stainless steel stents using intracoronary ultrasound.Methods Twenty de novo native coronary stenoses ≤ 20 mm in length (target vessel reference diameter ≥ 2.5 and ≤ 4.0 mm) received under sequential intracoronary ultrasound either a cobalt chromium stent (Multi-Link Vision®; n = 10) or a stainless steel stent (Multi-Link Zeta®; n = 10).Results For optimal unfolding, the cobalt chromium stent requires a higher balloon deployment pressure (13.90 ± 2.03 atm) than the stainless steel stent (11.50 ± 2.12 atm). Furthermore, the achieved target vessel diameter of the cobalt chromium stent (Visibility-Index QCA/IVUS Multi-Link Vision®1.13 / Multi-Link Zeta® 1.04) is more easily overrated by Quantitative Coronary Analysis.Conclusion These data indicate that stent material-specific recommendations for optimal implantation pressure and different stent material with an equal design should both be considered in interpreting QCA-analysis.