Improvement of postreceptor events by metoprolol treatment in patients with chronic heart failure.

OBJECTIVES: This study tested the hypothesis that metoprolol restores the reduction of the inotropic effect of the cyclic adenosine monophosphate (cAMP)-phosphodiesterase inhibitor milrinone, which is cAMP dependent but beta-adrenoceptor independent. BACKGROUND: Treatment with beta-adrenergic blocking agents has been shown to lessen symptoms and improve submaximal exercise performance and left ventricular ejection fraction in patients with heart failure. Restoration of the number of down-regulated beta-adrenoceptors has been suggested to be one mechanism of beta-blocker effectiveness. However, the reversal of postreceptor events, namely, an increase in inhibitory G-protein alpha-subunit concentrations, could also play a role. METHODS: Fifteen patients with heart failure due to dilated cardiomyopathy (left ventricular ejection fraction 24.6 +/- 1.5% [mean +/- SD], New York Heart Association functional class II or III) were treated with metoprolol (maximal dose 50 mg three times daily) for 6 months. Before and after metoprolol treatment, inotropic responses to milrinone (5 to 10 micrograms/kg body weight per min) were measured echocardiographically. For comparison, responses to milrinone were determined under control conditions and after accelerated application of 150 mg of metoprolol to inactivate beta-adrenoceptors in subjects with normal left ventricular function. RESULTS: In subjects with normal left ventricular function, treatment with metoprolol did not alter the increase in fractional shortening or pressure/dimension ratio of circumferential fiber shortening after application of milrinone. In patients with heart failure, treatment with metoprolol significantly increased left ventricular ejection fraction, fractional shortening and submaximal exercise tolerance and reduced heart rate, plasma norepinephrine concentrations and functional class. After metoprolol treatment, milrinone increased fractional shortening but had no effect before beta-blocker treatment. CONCLUSIONS: Milrinone increases inotropic performance independently of beta-adrenoceptors in vivo. Metoprolol treatment restores the blunted inotropic response to milrinone in patients with heart failure, indicating that postreceptor events (e.g., increase in inhibitory G-protein) are favorably influenced. This mechanism could contribute to the beneficial effects observed in the study patients and represents an important mechanism of how beta-blocker treatment influences the performance of the failing heart.

Assessment of viable myocardium by dobutamine transesophageal echocardiography and comparison with fluorine-18 fluorodeoxyglucose positron emission tomography.

OBJECTIVES: The aim of this study was to assess whether dobutamine transesophageal echocardiography can identify viable myocardium in patients with chronic myocardial infarction. BACKGROUND: Experimental and clinical studies have shown that dobutamine can recruit a contraction reserve in postischemic viable but akinetic segments, indicating that dobutamine-induced functional recovery is a potential ultrasound marker of myocardial viability. METHODS: Forty patients underwent rest and dobutamine transesophageal echocardiography (dobutamine 5, 10 and 20 micrograms/kg body weight per min) and fluorine-18 (F-18) fluorodeoxyglucose positron emission tomography at rest. Three representative short-axis tomograms and a transverse four-chamber-view were used for wall motion and F-18 fluorodeoxyglucose-uptake analysis in corresponding myocardial regions. A basally asynergic segment was considered viable by transesophageal echocardiography if dobutamine-induced systolic wall motion could be observed. Viability by positron emission tomography was defined as F-18 fluorodeoxyglucose uptake > or = 50% of the maximal uptake in a region with normal wall motion by left ventriculography. RESULTS: Functional recovery within the infarct region was found in 21 (53%) of 40 patients during dobutamine infusion. Infarct region-related viability by F-18 fluorodeoxyglucose uptake was diagnosed in 25 (63%) of 40 patients, yielding a diagnostic agreement between both techniques in 90% of patients. In 210 (89%) of 235 akinetic segments at rest, data on myocardial viability were concordant by the two techniques. The positive and negative predictive accuracy of dobutamine transesophageal echocardiography for viability defined by F-18 fluorodeoxyglucose uptake was 81% and 97%, respectively. Such uptake was significantly different (p < 0.001) between segments remaining akinetic (mean +/- SD 45 +/- 9%) during dobutamine infusion and segments with a dobutamine-induced contraction reserve (68 +/- 11%). CONCLUSIONS: Dobutamine transesophageal echocardiography provides a promising low cost and widely available approach to unmask myocardial viability in patients with chronic myocardial infarction, and results compare favorably with those of F-18 fluorodeoxyglucose positron emission tomography.

Regurgitant flow in cardiac valve prostheses: diagnostic value of gradient echo nuclear magnetic resonance imaging in reference to transesophageal two-dimensional color Doppler echocardiography.

Gradient echo nuclear magnetic resonance (NMR) imaging and transesophageal two-dimensional color Doppler echocardiography are flow-sensitive techniques that have been used in the diagnosis and grading of valvular regurgitation. To define the diagnostic value of gradient echo NMR imaging in the detection of regurgitant flow in cardiac valve prostheses and the differentiation of physiologic leakage flow from pathologic transvalvular or paravalvular leakage flow, 47 patients with 55 valve prostheses were examined. Color Doppler transesophageal echocardiography was used for comparison. Surgical confirmation of findings was obtained in 11 patients with 13 valve prostheses. Gradient echo NMR imaging showed regurgitant flow in 37 of 43 valves with a jet seen on transesophageal echocardiography and it detected physiologic leakage flow in 4 additional valves. There was 96% agreement between the two methods in distinguishing between physiologic and pathologic leakage flow. The methods differed on jet origin of pathologic leakage flow in six prostheses. The degree of regurgitation was graded by both NMR imaging and transesophageal echocardiography, according to the area of the regurgitant jet visualized; gradings were identical for 75% of valve prostheses. Quantification of jet length and area showed a good correlation between the two methods (r = 0.85 and r = 0.91, respectively). Gradient echo NMR imaging is a useful noninvasive technique for the detection, localization and estimation of regurgitant flow in cardiac valve prostheses. However, because transesophageal echocardiography is less time-consuming and less expensive, gradient echo NMR imaging is unlikely to displace transesophageal echocardiography and should be used only in the occasional patient who cannot be adequately imaged by echocardiography.

Predictive value of low dose dobutamine transesophageal echocardiography and fluorine-18 fluorodeoxyglucose positron emission tomography for recovery of regional left ventricular function after successful revascularization.

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. BACKGROUND: The identification of akinetic but viable myocardium is of particular importance for the selection of patients with a compromised left ventricle who will benefit from coronary revascularization. METHODS: Multiplane rest and dobutamine transesophageal echocardiography (dobutamine, 5 and 10 microg/min per kg) studies and F-18 fluorodeoxyglucose positron emission tomographic studies at rest were performed in 2 patients with 1) previous myocardial infarction and regional akinesia, 2) a stenosed infarct-related coronary artery, and 3) a patent infarct-related vessel after revascularization. A basally akinetic segment was considered viable by transesophageal echocardiography if dobutamine-induced contractile reserve could be observed. Viability by positron emission tomography was defined as F-18 fluorodeoxyglucose uptake > or = 50% of the maximal uptake in a region with normal wall motion. Recovery of regional left ventricular function 4 to 6 months after revascularization was diagnosed by transesophageal echocardiography if > or = 50% of segments akinetic at baseline had improved wall thickening. RESULTS: Dobutamine transesophageal echocardiography identified viable infarct regions in 25 (59%) of 42 patients, and F-18 fluorodeoxyglucose positron emission tomography in 30 (71%) of 42 patients, yielding diagnostic agreement in 86% of patients. Sensitivity and specificity for prediction of left ventricular functional recovery in individual patients was 92% and 88%, respectively, for dobutamine transesophageal echocardiography versus 96% and 69% for F-18 fluorodeoxyglucose positron emission tomography. Segments remaining akinetic after revascularization had a significantly lower (p < 0.001) F-18 fluorodeoxyglucose uptake (48 +/- 15%) than that (73 +/- 15%) of segments with recovery of regional left ventricular function. CONCLUSIONS: Both dobutamine transesophageal echocardiography and F-18 fluorodeoxyglucose positron emission tomography were highly sensitive in predicting functional recovery of chronically kinetic or dyskinetic myocardium after successful revascularization. Thus, dobutamine transesophageal echocardiography is a clinically valuable alternative to F-18 fluorodeoxyglucose positron emission tomography for assessing residual viability and predicting functional recovery after revascularization.

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.

Thrombus formation after transcatheter closure of atrial septal defect.

Thrombotic layers and/or atrial thrombi were detected by transesophageal echocardiography as a usual finding after transcatheter closure of atrial septal defects with the ASDOS device. The size of the thrombotic structures regularly decreased within 6 months without any clinical signs of embolization.

Magnetic resonance imaging of ductus arteriosus Botalli apertus in adulthood.

Ductus arteriosus Botalli apertus is a congenital cardiovascular malformation usually diagnosed in childhood by echocardiography and/or cardiac catheterization. Reports about magnetic resonance imaging of ductus arteriosus Botalli apertus are rare. We report about three adult female patients and one adult male patient in whom magnetic resonance imaging was able to demonstrate the pathology. In all four patients quantitative data about right ventricular function were calculated. Pulmonary hypertension with Eisenmenger syndrome detected by cardiac catheterization had developed in three of the four patients excluding operative closure of the ductus. The patient in whom pulmonary hypertension had not developed underwent successful operative closure of the ductus. Magnetic resonance imaging is a non-invasive tool that can be used for diagnosis of ductus arteriosus Botalli apertus and it allows to quantify right ventricular function. Magnetic resonance imaging can be used repetitively in patients with Eisenmenger syndrome which may be helpful for better timing of combined heart-lung transplantation as ultimate therapeutic strategy because deterioration of right ventricular function can be monitored.

Anomalous drainage of the right superior vena cava into the left atrium in a 61-year-old woman.

This report describes a 61-year-old female with an anomalous drainage of the right superior vena cava into the left atrium. The patient presented progressively severe dyspnea and precordial pain on exertion, lightheadedness, easy fatiguability and a constant decline in her performance but normal cardiac and pulmonary findings. Following a suspicious lung perfusion scan, diagnosis was assessed by echocardiography and confirmed by cardiac catheterization and nuclear magnetic resonance imaging. This anomaly leading to a right to left shunt appears to be a rare congenital cardiac malformation, particularly if diagnosed in the adult. The calculated shunt volume at rest was approximately 15% of the total body circulation. Although the functional relevance appears questionable, exercise of the upper limbs caused a significant decrease in systemic O2-saturation.

Congenitally corrected transposition of the great arteries (L-TGA) with situs inversus totalis in adulthood: findings with magnetic resonance imaging.

Diagnosis of congenitally corrected transposition of the great arteries (L-TGA) with situs inversus totalis in two adult patients was made by magnetic resonance imaging (MRI). Visualization of the complete anatomy and quantification of ventricular function was possible. Relevant concomitant disease such as perimembraneous ventricular septal defect, atrial secundum septal defect, tricuspid regurgitation, valvular pulmonic stenosis, and pulmonary artery dilatation were clearly depicted by MRI using standard spin-echo and gradient-echo techniques. Findings were confirmed by cardiac catheterization in both patients. In this rare and complex congenital cardiac anomaly, MRI is an excellent imaging modality as echocardiography may be difficult to interpret due to restricted imaging windows. MRI may help in the decision about the necessity to undergo further invasive evaluation and may help to make cardiac catheterization a straightforward procedure.

Long-term follow-up of 82 patients with chronic disease of the thoracic aorta using spin-echo and cine gradient magnetic resonance imaging.

The objective of this study to examine the clinical impact of magnetic resonance imaging in long-term follow-up of patients (pts) with chronic disease of the thoracic aorta such as coarctation of the aorta, chronic aortic dissection and true aortic aneurysm. A total of 322 magnetic resonance examinations obtained in 82 pts with chronic disease of the thoracic aorta (31 pts with coarctation of the aorta (CoA), 29 pts with chronic aortic dissection and 22 pts with true aneurysm) over a period of 0.25 to 13.5 (mean +/- SD: 6.5 +/- 3.4) years were retrospectively reviewed. Diameters of the thoracic aorta were measured at predefined levels and morphological and functional parameters of special interest were analysed in each patient group. Pts were classified as having constant or progressive disease and clinical end-points were defined as (re-)operation or death. 43 pts (52%) (CoA 15 pts, chronic dissection 16 pts, true aneurysm 12 pts) had constant findings. None of them underwent (re-)operation and seven patients (16%) died, three of them from their aortic disease more than five years later after their last magnetic resonance examination, one from an arrhythmogenic event, and in the remaining 3 pts the cause of death could not be definitely established. 39 pts (48%) (CoA 16 pts, chronic dissection 13 pts, true aneurysm 10 pts) had progressive disease as demonstrated by repetitive magnetic resonance imaging. Of these 39 pts 24 pts underwent (re-)operation, in 15 pts operation was postponed. Four pts died from their aortic disease. Repetitive magnetic resonance imaging is a clinically feasible technique for long-term follow-up of pts with chronic disease of the thoracic aorta because it can detect progressive disease in a large subset of pts requiring elective surgery. The results of magnetic resonance imaging provided the rationale for either (re-)operation or conservative management, thus guiding patient management.

Left ventricular geometry and function before and after mitral valve replacement.

Left ventricular geometry and function were assessed in 20 patients with mitral stenosis (MS) and in another 20 patients with mitral insufficiency (MI) five days before and 12 days after mitral valve replacement by transthoracic (TTE) and transesophageal (TEE) echocardiography, as well as late postoperatively (mean: 194 days) by TTE. The continuity of the subvalvular apparatus could not be preserved in any of these patients. In mitral stenosis the area ejection fraction (AEF) in the short axis of the left ventricle (LV) did not change significantly early or late postoperatively. There was a significant lengthening of the left ventricular longitudinal axis in the apical four chamber view whereas the transverse axis remained unchanged. This was likely the result of the discontinuity between the mitral valve and the papillary muscles. AEF and ejection fraction (EF) determined in the four chamber view showed a slight tendency to decrease in the postoperative phase. Patients with mitral insufficiency likewise showed a significant increase of the LV longitudinal diameter postoperatively. In the short axis of the left ventricle and in the apical four chamber view a significant reduction of the AEF was observed. Furthermore, left ventricular EF dropped significantly postoperatively. This decrease was caused by the extension of the LV longitudinal axis accompanied by an enlargement of the transverse diameter as well as by an afterload increase, and a masked impairment of left ventricular function preoperatively. Wall motion analysis of the LV in both groups documented new postoperative hypokinesis especially in the septal segments. At late postoperative examination the hypokinesis disappeared in about 50% of the patients.(ABSTRACT TRUNCATED AT 250 WORDS)

[Magnetic resonance tomography in patients with a heart valve prosthesis]. / Magnetresonanztomographie bei Patienten mit Herzklappenersatz.

Artificial valve prostheses are often regarded as a contraindication for magnetic resonance imaging (MRI), although preliminary in vitro studies suggested, that patients with these metallic implants might safely undergo MR examination. This study reports on the experience with a group of 89 patients with 100 heart valve prostheses who were examined by spin-echo MR and gradient-echo MR. MR examination was performed in all patients without complications. The spin-echo sequence showed advantages in the depiction of anatomical structures like paravalvular abscesses. Anatomical structures adjacent to the artificial valve were clearly visible and the metal components of the valves showed no or only small artifacts. Artifacts were accentuated when using gradient-echo sequences. Gradient-echo sequences provided valuable information regarding the presence of valvular insufficiency. Physiological valvular regurgitation was easy to differentiate from pathological paravalvular or transvalvular regurgitation. These results demonstrate that patients with artificial valve prostheses can be imaged by MR without risk and that prosthesis-induced artifacts do no interfere with image interpretation.

The role of nuclear medicine in diagnosis of catheter-related infections.

Infections represent a complication after transient or permanent implantation of medical devices (e.g. catheters or pacemaker systems), leading in many cases to therapeutic consequences such as the removal of the implanted system. Diagnosis of foreign body infections is difficult and mainly based on clinical findings rather than laboratory methods or modern morphological imaging tools. Two-dimensional echocardiography by transthoracic and transesophageal approach may be helpful in the detection of vegetations, but is not very sensitive for infections. Most methods in nuclear medicine, however, are based on function and not on form: some methods for the detection of an infection are unspecific like the use of labelled nanocolloids or Ga-67-citrate, or they need time-consuming and susceptible techniques for the labelling of autologous leukocytes. Monoclonal antibodies against epitopes on granulocytes, however, offer a fast and reliable in-vivo labelling technique. It has been demonstrated in a group of four patients that scintigraphic detection of pacemaker infections by immunoscintigraphy may represent a valuable diagnostic tool.

[Chylothorax as a postoperative complication of aortocoronary bypass operation]. / Der Chylothorax als postoperative Komplikation einer aortokoronaren Bypassoperation.

HISTORY AND CLINICAL FINDINGS: One month after a coronary bypass grafting operation, pericardial- und pleural effusions were found in a 75-year-old woman. Dressler-syndrome was assumed and an antiphlogistic and cortisone were prescribed. Under this therapy, the pericardial effusion disappeared, but the pleural effusion increased in size. After thoracocentesis, the diagnosis of a chylothorax could be confirmed. Three days later, the thoracic radiography was inconspicuous and the patient was discharged without changes in medication. As dyspnea occurred two weeks later, the patient was admitted to our hospital. INVESTIGATIONS: The thoracic radiography showed a reappearance of the pleural effusion. DIAGNOSIS, THERAPY AND COURSE: The laboratory test confirmed a relapse of the chylothorax. After a pleurodesis by drainage and a prescription of a high-caloric, fat-reduced diet the patient could be discharged two weeks later. The diet could be terminated two months later after a recurrence of the chylothorax had been excluded in the thoracic radiography. In the follow-up examinations, there was no evidence for a relapse of the chylothorax. CONCLUSIONS: The chylothorax is an uncommon postoperative complication of the aortocoronary bypass surgery. A relapse is likely and it can result in life-threatening cachexia. Therefore, a early and adequate therapy is important.

Cardiac function by magnetic resonance imaging.

Gated magnetic resonance imaging of the heart displays cardiac structures with excellent resolution. This ability should be useful for assessment of cardiac physiology where acquisition of systolic and diastolic images is required. In this study, left ventricular ejection fraction was determined in 50 patients from oblique long axis views of the left ventricle using the area length formula. Angulated views were obtained by electronic gradient angulation. For comparison, all patients had monoplane angiocardiography in the RAO position. Forty-five patients were also studied by radionuclide ventriculography. Ejection fractions determined by MRI and angiocardiography were closely correlated (r = 0.90). Correlation between MRI and radionuclide ventriculography was also acceptable (r = 0.79). In addition to global left ventricular function, MR images provide information about regional wall motion. In order to acquire a three-dimensional set of images at various phases of the cardiac cycle, shorter imaging times are mandatory. A new imaging technique with potential for functional studies uses low flip angles, short repetition times and gradient refocused echoes. Up to 40 images can be obtained within one cardiac cycle. When displayed in a looped fashion, visual assessment of cardiac motion, intracardiac blood flow, and systolic wall thickening is possible. Potential advantages of functional studies by MRI are the concomitant acquisition of anatomical information and the three dimensional frame of reference.