[The bleeding risk of arterial puncture during anticoagulation].
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Anticoagulants↗
Biomedical subjects
U Sechtem
Publications and source records attributed to U Sechtem.
Stress functional MRI: detection of ischemic heart disease and myocardial viability.
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.
Cardiotonic Agents↗
Delayed development of a coronary artery pseudoaneurysm after angioplasty.
One month after a successful angioplasty, one of our patients developed a new aneurysm in the right coronary artery (RCA). The aneurysm was characterized as a pseudoaneurysm by the use of intravascular ultrasound (IVUS). A stenosis that was not well seen by angiography was better depicted by IVUS. Both the pseudoaneurysm and the stenosis were successfully treated with a second angioplasty and stenting with a covered stent. Delayed development of pseudoaneurysms after dissection is an uncommon, but possible complication after angioplasty. In this case IVUS was useful for accurate characterization of the aneurysm. The use of covered stents may become a clinically useful method for treating coronary pseudoaneurysms.
Aged↗
[Magnetic resonance tomography in cardiology. Guidelines of the Commission on Clinical Cardiology of the German Society of Cardiology--Heart and Circulation Research].
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Cardiomyopathies↗
Improvement of myocardial blood flow to ischemic regions by angiotensin-converting enzyme inhibition with quinaprilat IV: a study using [15O] water dobutamine stress positron emission tomography.
OBJECTIVES: This study was designed to analyze the effects of acute angiotensin-converting enzyme (ACE) inhibition on myocardial blood flow (MBF) in control and ischemic regions. BACKGROUND: Although animal studies indicate an improvement of MBF to ischemic regions after ACE inhibition, this effect has not been conclusively demonstrated in patients with coronary artery disease. METHODS: Myocardial blood flow was analyzed in ischemic and nonischemic regions of 10 symptomatic patients with coronary artery disease using repetitive [15O] water positron emission tomography at rest and during maximal dobutamine stress before and after ACE inhibition with quinaprilat 10 mg i.v. To exclude the possibility that repetitive ischemia may cause an increase in MBF, eight patients underwent the same protocol without quinaprilat (placebo patients). RESULTS: Rate pressure product in control and quinaprilat patients was comparable. In placebo patients, repetitive dobutamine stress did not change MBF to ischemic regions (1.41 +/- 0.17 during the first stress vs. 1.39 +/- 0.19 ml/min/g during the second stress, p = 0.93). In contrast, MBF in ischemic regions increased significantly after acute ACE inhibition with quinaprilat during repetitive dobutamine stress (1.10 +/- 0.13 vs. 1.69 +/- 0.17 ml/min/g, p < 0.015). Dobutamine coronary reserve in ischemic regions remained unchanged in placebo patients (1.07 +/- 0.11 vs. 1.10 +/- 0.16, p = 0.92), but increased significantly after quinaprilat (0.97 +/- 0.10 vs. 1.44 +/- 0.14, p < 0.002). Total coronary resistance decreased after ACE inhibition (123 +/- 19 vs. 71 +/- 10 mm Hg x min x g/ml, p < 0.02). CONCLUSIONS: Angiotensin-converting enzyme inhibition by quinaprilat significantly improves MBF to ischemic regions in patients with coronary artery disease.
Adult↗
Intravascular ultrasonography in the evaluation of results of coronary angioplasty and stenting.
The main advantage of intravascular ultrasonography (IVUS) over angiography in assessing the effect of coronary interventions is the ability of IVUS to directly visualize the vessel wall. IVUS often reveals a high residual plaque burden after angiographically successful angioplasty, and this can motivate the operator to use additional, more aggressive measures in an attempt to increase lumen dimensions. Studies using IVUS imaging before and after balloon angioplasty have shown that luminal gain after percutaneous transluminal coronary angioplasty (PTCA) results from a combination of plaque reduction and vessel wall stretch. Minimal luminal area and residual area stenosis after PTCA and stent deployment, as measured by IVUS, have been shown to be predictors of restenosis. IVUS studies have pointed to vessel shrinkage, not intimal hyperplasia, as the main mechanism of restenosis after PTCA. IVUS guidance of stent deployment has often revealed inadequate stent expansion despite optimal results on angiography, leading to high-pressure stent deployment with significant additional luminal gain. Restenosis rates may be lower with IVUS-guided stent deployment.
Angioplasty, Balloon, Coronary↗
Comparison of angioscopic, intravascular ultrasonic, and angiographic detection of thrombus in coronary stenosis.
Coronary angioscopy, intravascular ultrasound, and angiography were compared in 20 patients regarding their sensitivity and specificity in the detection of thrombus. Although all imaging procedures demonstrate a high specificity, only coronary angioscopy has a sensitivity high enough to provide sufficient evidence of thrombus, even in patients with stable angina.
Aged↗
Significance of exercise-induced ST-segment elevation and T-wave pseudonormalization for improvement of function in healed Q-wave myocardial infarction.
Exercise-induced ST-segment elevation and pseudonormalization of negative T waves (ST-T segment changes) in infarct leads indicate myocardial viability after Q-wave myocardial infarcts in some patients and may therefore identify patients who will benefit from revascularization. Global left ventricular ejection fraction and wall motion abnormalities of the left ventricle were analyzed in 34 patients with healed myocardial infarction (11 patients with ST-segment elevation, 3 patients with pseudonormalization of the negative T wave (group 1), and in 20 patients without ST-T segment changes during an exercise electrocardiogram (group 2)) before and 4 months after successful revascularization. Wall motion abnormality in the central infarct region at baseline was similar in both groups (-3.1 +/- 0.6 SD vs 3.0 +/- 0.8 SD; NS). At repeat angiography, wall motion abnormality improved significantly from -3.1 +/- 0.6 SD to -2.1 +/- 0.6 SD (p <0.01) in group 1 and was unchanged in group 2 (-3.0 +/- 0.8 SD vs -2.9 +/- 0.7 SD; NS). Similarly, ejection fraction at control angiography had increased from 54 +/- 14% to 66 +/- 12% (p <0.01) in group 1, but decreased from 56 +/- 9% to 55 +/- 9% in group 2 (NS). Exercise-induced ST-T segment changes yielded a sensitivity of 80% and a specificity of 89% to predict significant improvement of the left ventricular ejection fraction. Exercise-induced changes of the ST-T segment identify patients with a high probability of improvement of myocardial function after revascularization in patients with healed myocardial infarcts.
Adult↗
[Magnetic resonance tomography in diagnosis of cardiac space-occupying lesions].
Imaging of cardiac masses is technically highly demanding. Imaging techniques should fulfill the following requirements: excellent spatial and temporal resolution, short imaging time, broad availability, low cost. Diagnostic questions include: tumor origin, size, extension, tissue type, functional consequences of tumor involvement. Transthoracic echocardiography is the imaging technique of choice in most patients. If clinical questions remain, TEE, CT or MRI can be used as secondary imaging techniques. Advantages of MRI include: excellent spatial and temporal resolution, multiplanar capabilities, large field of view, lack of radiation. Pericardial and intracardiac as well as paracardiac masses are depicted in great detail and therapeutically relevant information is usually obtained in addition to what is known from echocardiography. Although tissue differentiation is possible, a histologic diagnosis cannot be obtained. Disadvantages of MRI are artifacts in patients with severe arrhythmias or dyspnoea.
Heart Neoplasms↗
Dobutamine magnetic resonance imaging predicts contractile recovery of chronically dysfunctional myocardium after successful revascularization.
OBJECTIVES: This study sought to evaluate whether myocardial viability, as assessed by magnetic resonance imaging (MRI), reliably predicts postrevascularization left ventricular (LV) recovery. BACKGROUND: Compared with positron emission tomographic findings, MRI has proved to be a reliable technique for the identification of residual myocardial viability. However, the predictive accuracy of MRI-assessed preserved end-diastolic wall thickness (DWT) and dobutamine-induced systolic wall thickening (SWT) for LV functional recovery has not yet been evaluated. METHODS: Rest and low dose dobutamine MRI was performed in 43 patients with a chronic infarct (> or =4 months since ischemic event) and LV dysfunction who had undergone revascularization of the infarct-related vessel. On the basis of segmental evaluation of corresponding short-axis tomograms, infarct regions were graded viable by MRI if 1) DWT was > or =5.5 mm, and 2) dobutamine-induced SWT was > or =2 mm in > or =50% of dysfunctional segments related to the infarct region. Functional recovery was defined as SWT > or =2 mm in > or =50% of infarct-related segments at rest 4 to 6 months after successful revascularization. RESULTS: Recovery of regional SWT could be observed in 27 (63%) of 43 patients. Comparison MRI grading before and after revascularization indicated that dobutamine-induced SWT was a better predictor of LV functional recovery (sensitivity 89%, specificity 94%) than was preserved DWT (sensitivity 92%, specificity 56%). Segments that remained akinetic after revascularization had significantly lower DWT (6.0+/-3.1 mm [n = 219] vs. 9.8+/-2.6 mm [n = 188], p < 0.001) than those with improved SWT. Left ventricular ejection fraction increased significantly in patients with dobutamine-induced SWT than in those with no contractile reserve (14+/-9% vs. 3+/-9%, p < 0.0002), and the magnitude of this increase was correlated with the number of dobutamine-responsive segments per infarct region (r = 0.68, p < 0.0001). CONCLUSIONS: Quantitative assessment of dobutamine-induced SWT in chronic infarcts by MRI is a highly accurate predictor of LV functional recovery, and the presence of significantly reduced DWT reliably indicates irreversible myocardial damage. Therefore, dobutamine stress testing for the assessment of myocardial viability can be restricted to patients with preserved DWT.
Adult↗
Significance of rest technetium-99m sestamibi imaging for the prediction of improvement of left ventricular dysfunction after Q wave myocardial infarction: importance of infarct location adjusted thresholds.
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. BACKGROUND: The value of rest Tc-99m sestamibi to predict viability in infarct regions has not been fully established because significant underestimation of viability, especially in the inferior myocardial wall, has been reported. METHODS: Forty patients with Q wave myocardial infarction underwent Tc-99m sestamibi single-photon emission computed tomography under nitrate medication before revascularization of the infarct-related artery. Wall motion was quantified from paired angiograms before and 4 months after revascularization. Tracer uptake was quantified in the central infarct region identified on the angiogram. RESULTS: The average Tc-99m sestamibi uptake in the central infarct region of patients with anterior infarcts and improvement of left ventricular function was significantly higher (68+/-12%, mean+/-SD) than in patients without improvement of function (40+/-14%, p < 0.02). The average Tc-99m sestamibi uptake in the central infarct region of patients with improvement of function and inferior infarcts was significantly lower (43+/-7%) than in patients with anterior infarcts (68+/-12%, p < 0.003), but was significantly higher than in patients with inferior infarction and no improvement of function (31+/-7%, p < 0.02). Using an infarct location adjusted optimal threshold (50% for anterior infarcts, 35% for inferior infarcts), Tc-99m sestamibi had a positive predictive value of 90% and a negative predictive value of 91% for improvement of left ventricular function. CONCLUSION: Quantitative rest Tc-99m sestamibi scintigraphy after oral nitrates reliably predicts improvement of left ventricular function after revascularization if infarct location adjusted thresholds are used.
Aged↗
QT dispersion is determined by the extent of viable myocardium in patients with chronic Q-wave myocardial infarction.
BACKGROUND: QT dispersion is lower in patients with successful thrombolysis after acute myocardial infarction, suggesting that QT dispersion may be determined by the extent of viable and scarred myocardium. METHODS AND RESULTS: To test this hypothesis, QT dispersion was measured in a 12-lead resting ECG in 44 patients with chronic Q-wave myocardial infarction. To assess the extent of viable and scarred myocardium, all patients underwent F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET). In addition, all patients had revascularization of the infarct-related artery and repeated angiography 4 months later. QT dispersion was lower (53+/-20 versus 94+/-24 ms, P<.0001) in patients with evidence of a substantial amount of viable myocardium in the infarct region as demonstrated by PET (average FDG uptake > or = 50% of normalized, maximum FDG uptake) than in patients with only minimal residual viability. Average FDG uptake of the infarct region and FDG defect size were significantly related to QT dispersion (r=.64, P<.0001; r=.67, P<.0001), whereas ejection fraction was not (r<.1, P=NS). QT dispersion of < or = 70 ms had a sensitivity of 85% and a specificity of 82% to predict viable myocardium in the infarct region. QT dispersion was also lower in patients with improvement of left ventricular function 4 months after revascularization (54+/-21 versus 88+/-30 ms, P=.0003). QT dispersion of < or = 70 ms had a sensitivity of 83% and a specificity of 71% to predict improvement of left ventricular function. CONCLUSIONS: QT dispersion is determined by the amount of viable myocardium in the infarct region and may serve as a novel, rapidly available marker of substantial viability in the infarct region of patients with chronic Q-wave myocardial infarction.
Angioplasty, Balloon, Coronary↗
Assessment of myocardial perfusion by magnetic resonance imaging.
Magnetic resonance imaging (MRI) has proven useful for anatomic and functional evaluation of the heart. However, until recently assessment of myocardial perfusion has not been possible by MRI. Using newly developed ultrafast imaging sequences, images can be acquired rapidly with a high temporal resolution, which is a prerequisite for imaging the initial passage of a bolus of MR-contrast medium through the myocardium. Only gadolinium chelates, which rapidly diffuse out of vascular space, are currently approved for clinical use. The first pass of a bolus of one of these agents through hypoperfused myocardium distal to a coronary artery stenosis enhances this area less as compared to normally perfused areas. This different myocardial enhancement is often visible when looking at the series of MR images. However, intensity differences are rapidly decreasing as MR-contrast media are diluted in the systemio circulation after the first pass and diffuse to the interstitium. Therefore, only the first pass is of interest for MR-perfusion imaging. Additional and often more precise information can be derived by measuring parameters of the signal intensity time curve such as mean transit time, maximum signal intensity increase, upslope, downslope, and delay before reaching maximum signal intensity. Temporal resolution is the crucial factor in MR-perfusion imaging because it takes only 20 to 60 seconds for the contrast medium to pass through the myocardium. Therefore, this dynamic process must be imaged with a high temporal resolution. Moreover, image acquisition must be fast enough to minimize motion artefacts and to maximize the spatial coverage of the ventricle. Ultrafast gradient echo techniques and echo planar imaging are in principle capable to fulfill these demands. While ultrafast gradient echo sequences enable one to acquire a maximum of 2 slices per heartbeat, echo planar sequences need only 30 to 50 msec to completely acquire one image and are thus able to image the entire ventricle within one heartbeat. However, they are also more susceptible to image artefacts. As gradients capable of producing high quality echo planar images are not widely available, ultrafast gradient echo techniques are commonly used for MR-perfusion imaging. A good correlation between quantitative estimates of myocardial perfusion by MRI after injection of an intravascular contrast agent and microsphere measurements has been shown in animal experiments but quantitative MR perfusion measurements have not yet been performed in humans. Clinical studies have until now focused on visual and parametric analysis of signal intensity time curves. From these studies, sensitivities and specifities in the range of 60 to 90% as compared to x-ray coronary angiography and scintigraphy were reported despite the fact that only parts of the left ventricular myocardium could be assessed. However, a generally accepted method of acquiring and analysing MR perfusion images does not yet exist. Therefore, future improvements of hardware and pulse-sequences as well as the development of new blood pool contrast agents are necessary before MR-perfusion imaging will become a widely accepted and clinically useful diagnostic procedure.
Artifacts↗
[Non-transmural anterior wall infarct: changes in myocardial energy metabolism in remaining vital myocardium].
To characterize energy metabolism in vivo after nontransmural anterior myocardial infarction, patients (group A, n = 19) with a stenosis of left anterior descending artery (LAD) and anterior wall hypokinesia by levocardiography were examined by phosphorus magnetic resonance spectroscopy (MRS). Spectra were compared to those of healthy volunteers (n = 15). The volume of interest was placed into the anterior myocardial wall by magnetic resonance imaging. Phosphorus spectra were recorded under optimal antiischemic medication. To separate the influence of coronary stenosis from that of the ischemic insult, additional patients (group B, n = 4) with LAD-stenosis but without left ventricular dysfunction were examined. The effect of antiischemic medication on the phosphorus spectra was evaluated in patient group C (n = 4), who had the same clinical features as group A. In these patients, MRS was first performed without antiischemic medication (washout period > one day) and then repeated during intravenous application of glyceroltrinitrate (GTN). Mean PCr/ATP-ratio was significantly lower in group A patients (1.24 +/- 0.18) than in healthy volunteers (1.74 +/- 0.23; p < 0.01 unpaired t-test). Patients with normal left ventricular function (group B) showed PCr/ATP-ratios (1.64 +/- 0.22) similar to those of normal controls (p = 0.23). After GTN infusion PCr/ATP-ratio of group C rose from 1.12 +/- 0.08 to 1.32 +/- 0.13 (p < 0.01 paired t-test). Thus, hypokinetic myocardium after nontransmural infarction is characterized by a larger decrease of the cellular energy buffer PCr compared to the myocardial ATP-content. These findings may reflect degenerative changes of myocytes due to disturbed microperfusion in viable areas of the infarct or remodeling processes of viable myocytes in the infarct region. Both mechanisms may lead to adaptive changes of cellular enzyme concentrations resulting in a reduced PCr content of the myocytes.
Adenosine Triphosphate↗
[Intracoronary ultrasound changes the therapeutic approach in ambivalent angiography findings].
Despite careful evaluation of multiple projections, coronary angiography may give ambiguous results of lesion severity. The purpose of this study was to analyze the impact of ultrasound imaging on revascularization treatment strategy in angiographically ambiguous findings. We reviewed our experience with such equivocal angiographic findings before intervention in 31 patients (34 lesions) who had additional intravascular ultrasound (IVUS) to clarify coronary anatomy. Intervention was felt to be indicated if area stenosis by IVUS exceeded 50% in the left main or 75% in other major coronary arteries. To evaluate the clinical efficacy of IVUS based management strategies, all patients had clinical follow-up after 1 year. Seven of nine ostial lesions were overestimated by angiography, but two of three left main lesions were found to be significant. Seven lesions in one of the proximal coronary arteries whose significance was difficult to judge by angiography were found not to be significant by IVUS, whereas in the other four severe obstruction was confirmed. Membranes by angiography corresponded to remnants of ruptured plaques by IVUS in all five patients. However, significant narrowing was found in only two patients. Side branch ostial lesions were ruled out by IVUS in all four instances. Two patients with unstable angina but normal angiograms showed complex atherosclerotic plaques in the left coronary artery. IVUS led to a change of therapy in 21 patients (revascularization instead of conservative treatment in two and cancellation of initially intended intervention in 19). At follow-up examination, 17 of these 21 patients were free of cardiac symptoms. Interventions at the site thought not severely diseased by IVUS had to be performed in two patients with persistent angina who were afterwards free of symptoms. One patient with persistent chest pain had a second coronary angiogram during the follow-up period, but conservative therapy was continued. Evaluation was impossible in one patient because of bypass surgery due to another coronary lesion. In conclusion, IVUS was clinically useful in patients with angiographically ambiguous findings and resulted in a change of therapy in 21/31 patients obviating interventions in 19 patients with excellent clinical results.
Adult↗
Magnetic resonance imaging in valvular heart disease.
Magnetic resonance techniques can be employed to depict valvular abnormalities but are especially helpful in quantifying regurgitant or stenotic lesions which cannot be quantitatively assessed by other noninvasive techniques. Gradient echo techniques and phase velocity mapping are the most important magnetic resonance pulse sequences employed for these purposes. Valvular regurgitation can be quantitated by measuring the area of signal void on conventional gradient-echo images, by calculating stroke volume differences from k-space segmented gradient echo images, by measuring the proximal convergence zone from velocity encoded images or by comparing stroke volumes of the ventricles from velocity measurements. In contrast to this variety of possibilities in regurgitant lesions, stenotic lesions can only be quantitated by using velocity mapping techniques. Magnetic resonance spectroscopy can be used to assess myocardial metabolism in chronic valvular lesions. However, this tool needs further development and more clinical data before its use can be recommended to assess the necessity and optimal timing of surgical intervention.
Aortic Valve Insufficiency↗
Dipyridamole scintigraphy and intravascular ultrasound after successful coronary intervention.
UNLABELLED: Despite angiographically successful interventions, perfusion defects are not uncommonly observed in postinterventional perfusion scintigrams. The aim of this study was to test the hypothesis that perfusion defects after coronary intervention are associated with a significant residual stenosis in the treated vessel segment detectable by intravascular ultrasound but not by angiography. METHODS: Forty consecutive patients with angiographically successful coronary interventions were prospectively studied by intravascular ultrasound immediately after the intervention. Within 48 hr after the intervention all patients had myocardial scintigraphy using 99mTc-methoxyisobutyl-isonitrile SPECT after dipyridamole stress. Myocardial perfusion defects in the scintigram were assigned to a segmental left ventricular model and compared to the perfusion territory of the treated vessel estimated from the coronary angiogram. RESULTS: Twenty of 40 patients had reversible myocardial perfusion defects. Mean ultrasound area stenosis was 50% in these patients and 33% in patients without perfusion defects (p < 0.002); ultrasound percent plaque area was 75% versus 63% (p < 0.0001), respectively. The best concordance between residual area stenosis and perfusion defects was found for an ultrasound area stenosis > or = 40%. CONCLUSION: Patients with stress-induced myocardial perfusion defects immediately after successful coronary intervention show high-grade residual stenoses that are more pronounced in patients with perfusion defects than in patients with normal postinterventional scintigrams. In addition, vessels serving myocardial regions with perfusion defects showed a significantly higher plaque burden indicating diffuse atherosclerotic changes in the vessel. The evaluation of the postprocedural result by intravascular ultrasound contributes to a better understanding of the discrepancy between the angiographic finding of a widely patent vessel but scintigraphic evidence of impaired perfusion.
Adult↗
Comparison of dobutamine transesophageal echocardiography and dobutamine magnetic resonance imaging for detection of residual myocardial viability.
A dobutamine-induced contraction reserve in akinetic but viable myocardium, observed by echocardiography or magnetic resonance imaging (MRI), is a reliable indicator of myocardial viability. However, the comparative diagnostic accuracy of these 2 techniques is unknown. Therefore, 43 patients with myocardial infarction (infarct age > or = 4 months) and regional akinesia underwent dobutamine transesophageal echocardiography (TEE) and dobutamine MRI (10 microg dobutamine/ min/kg). Both imaging techniques were compared with the reference standard 18F-fluorodeoxyglucose positron emission tomography (FDG PET). An infarct region was considered viable if a dobutamine contraction reserve could be assessed visually by TEE or quantitatively by MRI in > or = 50% of segments graded "a" or dyskinetic at rest. Infarct regions were graded viable by PET if FDG uptake was > or = 50% of the maximal FDG uptake in a region with normal wall motion by left ventriculography. A dobutamine contraction reserve was found in 21 of 43 patients (49%) by TEE and MRI. A viable infarct region by FDG PET was diagnosed in 26 of 43 patients (60%). FDG uptake and dobutamine TEE were concordant in 36 of 43 patients (84%) and dobutamine MRI and FDG PET were concordant in 38 of 43 patients (88%). Sensitivity and specificity of dobutamine TEE and dobutamine MRI for FDG PET-defined myocardial viability were 77% versus 81% and 94% versus 100%, respectively. Both imaging techniques yielded similar results for the detection of myocardial viability as defined by FDG uptake, with a slightly higher sensitivity and specificity for the quantitatively evaluated dobutamine contraction reserve by MRI.
Adrenergic beta-Agonists↗