M. Elizabeth Brickner

Usefulness of dobutamine echocardiography in distinguishing severe from nonsevere valvular aortic stenosis in patients with depressed left ventricular function and low transvalvular gradients

Abstract The safety of dobutamine echocardiography in coronary artery disease is well established. 27 This study shows that dobutamine can be given safely to patients with AS during noninvasive hemodynamic monitoring. The small number of patients in this study preclude assessment of the effect of dobutamine echocardiography on outcome. A large prospective study is indicated. Although the continuity equation does not contain a flow-dependent constant, its limitations include underestimation of LV outflow diameter and failure to properly align the Doppler beam. 18 However, even if errors in velocity measurement occurred, directional changes should be valid since the transducer locations were identical at baseline and dobutamine infusion.

The Eisenmenger Syndrome in Adults

In 1897, Vicktor Eisenmenger described a patient with cyanosis and dyspnea since infancy who died of massive hemoptysis at 32 years of age. Postmortem examination showed a ventricular septal defect and severe pulmonary vascular disease [1]. In 1958, Paul Wood coined the term Eisenmenger complex to describe pulmonary hypertension at the systemic level due to a high pulmonary vascular resistance, with reversed or bidirectional shunting through a large ventricular septal defect [2]. Subsequently, the term Eisenmenger syndrome has been used to describe pulmonary vascular disease and cyanosis resulting from any systemic-to-pulmonary circulation connection (such as an atrial septal defect, ventricular septal defect, patent ductus arteriosus, or aortopulmonary window). Pathophysiology We reviewed the literature on the pathophysiology, clinical features, natural history, prognosis, and management of the Eisenmenger syndrome in adults. English-language articles from 1966 to the present were identified through a search of the MEDLINE database by using the terms Eisenmenger, congenital heart disease, and pulmonary hypertension. We also included selected cross-referenced articles. Articles on the pathophysiology, clinical presentation, evaluation, natural history, complications, and treatment of the Eisenmenger syndrome in adults were selected, and descriptive and analytical data relevant to the practicing physician were manually extracted. In patients with intracardiac shunting, blood initially shunts from the systemic to the pulmonary circulation (so-called left-to-right shunting) because the resistance in the former is higher. If the defect is large and the left-to-right shunting is sustained (for example, over months to years), exposure of the pulmonary vasculature to systemic arterial pressure or increased blood flow leads to progressive morphologic changes in the microvasculature (Figure 1), including arteriolar medial hypertrophy, intimal proliferation and fibrosis, and capillary and arteriolar occlusion. Eventually, plexiform lesions and necrotizing arteritis occur [3], with resultant obliteration of pulmonary arterioles and capillaries and increased pulmonary vascular resistance. Finally, pulmonary vascular resistance and pulmonary arterial pressure approach systemic vascular resistance and systemic arterial pressure, and the shunt reverses. Figure 1. Pathophysiology of the Eisenmenger syndrome. The pathophysiologic mechanisms responsible for the development of pulmonary microvascular changes in patients with the Eisenmenger syndrome are not completely known. In experimental animals, pulmonary microvascular injury stimulates the production of elastase enzymes and growth factors (that is, insulin-like growth factor I and transforming growth factor), which may cause medial hypertrophy, cellular intimal proliferation, progressive occlusion, and eventual destruction of small arterioles [4-6]. Endothelium-dependent pulmonary arteriolar relaxation is impaired, pulmonary endothelin production is increased, and plasma thromboxane B2 concentrations are elevated in patients with the Eisenmenger syndrome, suggesting that endothelial dysfunction or platelet activation may play a causative role in this condition [7-11]. Clinical Presentation Patients with the Eisenmenger syndrome often have a history of transient pulmonary congestion in infancy as a result of a substantial pulmonary blood flow caused by a large left-to-right intracardiac shunt. Later in infancy or in early childhood, as pulmonary vascular resistance increases, pulmonary blood flow declines, and symptoms of pulmonary congestion abate. When the shunt reverses (that is, when right-to-left shunting occurs), cyanosis and erythrocytosis develop. Less commonly, patients develop the Eisenmenger syndrome in adulthood without obvious symptoms during childhood and seek medical attention because of progressive fatigue, dyspnea, or cyanosis. Eventually, most patients with the Eisenmenger syndrome have one or more of the following conditions: 1) symptoms of a low systemic output [such as dyspnea on exertion, fatigue, or syncope], 2) subtle neurologic abnormalities [such as headache, dizziness, or visual disturbances] due to erythrocytosis and hyperviscosity, or 3) symptoms of congestive heart failure. In addition, arrhythmias and hemoptysis are common, and the former may lead to sudden death. Hemoptysis is caused by pulmonary infarction; rupture of a pulmonary artery dilated by aneurysm or a thin-walled pulmonary arteriole; or bleeding diathesis, which often manifests initially as mucosal (that is, epistaxis or gingival) bleeding. Cerebrovascular accidents frequently occur as a result of hyperviscosity, paradoxical embolism, or a cerebral abscess. Physical Examination Physical examination of the patient with the Eisenmenger syndrome reveals central cyanosis and clubbing of the nail bed. If systemic vascular resistance falls, as may occur with hot weather, exercise, fever, or systemic infection, the magnitude of right-to-left shunting and cyanosis increases. Patients with a patent ductus arteriosus may have normal, pink nail beds on the right hand and cyanosis and clubbing of the nail beds on the left hand and both feet (so-called differential cyanosis). This occurs because venous blood shunts through the ductus and enters the aorta distal to the right subclavian artery. The jugular venous pressure may be normal or elevated, with a prominent V wave if tricuspid regurgitation is present. The arterial pulse is usually diminished or normal [2]. Signs of pulmonary hypertension, including a right parasternal heave, a palpable pulmonary valve closure, a right-sided fourth heart sound, and a loud pulmonic component of the second heart sound, are uniformly present. The second heart sound may be single (such as with ventricular septal defect) or widely split (such as with atrial septal defect). A high-pitched, diastolic, decrescendo murmur of pulmonic regurgitation (Graham Steell murmur) is often audible, and a holosystolic murmur of tricuspid regurgitation may occur when right heart failure intervenes. In many patients, a pulmonary ejection click and soft systolic ejection murmur are audible and are attributable to dilation of the main pulmonary artery. Murmurs usually associated with ventricular septal defect or patent ductus arteriosus are absent. The lung fields are clear, and peripheral edema is absent unless right ventricular systolic dysfunction ensues. Noninvasive and Invasive Evaluation In patients with the Eisenmenger syndrome, 12-lead electrocardiography shows right atrial enlargement and right ventricular or biventricular hypertrophy. Atrial arrhythmias are often present, especially in patients with atrial septal defects. Chest radiography usually reveals prominent, dilated central pulmonary arteries with a reduction in the size and number of peripheral vessels. Calcification of the pulmonary arteries or ductus arteriosus, signifying atherosclerosis, may be visualized. Patients with the Eisenmenger syndrome who have ventricular septal defect or patent ductus arteriosus usually have a normal or minimally increased cardiothoracic ratio, whereas most patients with the syndrome who have atrial septal defect have cardiomegaly [12] with dilation attributed to right ventricular enlargement caused by previously increased flow [2]. Two-dimensional echocardiography is helpful in visualizing intracardiac defects and identifying associated cardiac or valvular abnormalities. Color flow Doppler imaging usually can detect intracardiac shunting. However, because the pulmonary and systemic arterial pressures are similar in patients with the Eisenmenger syndrome, the pressure gradient and flow across the intracardiac defect may be small and therefore difficult to visualize by color flow Doppler imaging [13]. In such patients, contrast echocardiography should be performed. An intravenously injected contrast agent (such as agitated normal saline, indocyanine green, or hydrogen peroxide) quickly appears in the left heart chambers when a right-to-left intracardiac shunt is present; the magnitude of intracardiac right-to-left shunting can be assessed qualitatively as small, moderate, or large but cannot be quantitated precisely [14, 15]. Transesophageal echocardiography can be performed safely in patients with the Eisenmenger syndrome and is superior to the transthoracic approach for detecting atrial septal abnormalities or patent ductus arteriosus [13, 16]. It is valuable for evaluating patients with unexplained pulmonary hypertension. Transesophageal echocardiography should be performed in patients with the Eisenmenger syndrome who are being considered for lung transplantation because it provides additional diagnostic information (such as the presence of additional unsuspected intracardiac defects, unrecognized intracardiac shunts, or proximal pulmonary artery thrombus) that may alter surgical intervention in approximately 25% of patients [16, 17]. Magnetic resonance imaging can identify intracardiac defects and patent ductus arteriosus and is particularly useful in patients with previous cardiac surgery in whom echocardiographic evaluation is technically difficult [18-21]. Although this test provides excellent visualization of the pulmonary and systemic arterial systems and cardiac chambers, it is limited in its ability to identify structural valvular abnormalities. Cine magnetic resonance imaging can detect right-to-left or bidirectional intracardiac shunting but has not yet proven useful in assessing the magnitude of shunting. In patients suspected of having the Eisenmenger syndrome, cardiac catheterization should be performed to detect, localize, and quantitate intracardiac shunting and to determine the severity of pulmonary vascular disease [15]. The assessment of pulmonary vascular resistance before and after administration of a pulmonary arteriolar vasodilator (that is, 100% oxygen o

Multiplane transesophageal echocardiographic assessment of mitral regurgitation by Doppler color flow mapping of the vena contracta

Assessment of the severity of mitral regurgitation (MR) by Doppler color flow mapping is limited by dependence of jet area on hemodynamic and technical variables. The width of the MR jet at its origin may be less dependent on hemodynamic variables, and thus should more accurately reflect the severity of MR. Doppler color flow mapping was performed in 80 subjects by transesophageal echocardiography (TEE) within 48 hours of catheterization. Width of the MR jet at its vena contracta was measured by both single plane and multiplane TEE and compared with the angiographic grade of MR and regurgitant volume. The width of the MR jet correlated closely with angiographic grade by both methods. A jet width > or = 6 mm identified angiographically severe MR with a sensitivity and specificity of 100% and 83% by single-plane TEE, and 95% and 98% by multiplane TEE. The sensitivity and specificity for detecting a regurgitant volume > or = 80 ml was 93% and 76% for single-plane TEE, and 86% and 95% for multiplane TEE. Thus, the width of the MR jet at its vena contracta by Doppler color flow mapping is an accurate marker of the severity of MR. By virtue of its ability to obtain orthogonal views specifically oriented to mitral leaflet coaptation, multiplane TEE is superior to single-plane TEE in assessing MR jet width.

Effects of afterload reduction on vena contracta width in mitral regurgitation

OBJECTIVES We used color Doppler flow mapping to determine whether vena contracta width (VCW) is a load-independent measure of the severity of mitral regurgitation. BACKGROUND VCW has been proposed to be a relatively load-independent measure of mitral regurgitation severity in flow models using a fixed orifice. However, in patients with mitral regurgitation, VCW may not be load independent because of a dynamic regurgitant orifice. METHODS VCW, effective regurgitant orifice area and regurgitant volume were measured by quantitative Doppler mapping in 31 patients with chronic mitral regurgitation at baseline and during nitroprusside infusion. Patients with rheumatic heart disease, annular calcification or endocarditis were considered to have a fixed regurgitant orifice, whereas patients with mitral valve prolapse, dilated cardiomyopathy or ischemia were considered to have a dynamic regurgitant orifice. RESULTS Systolic blood pressure (148 +/- 27 to 115 +/- 25 mm Hg) and end-systolic wall stress (121 +/- 50 to 89 +/- 36) decreased with nitroprusside (p < 0.05). Although nitroprusside did not significantly change mean values for VCW (0.5 +/- 0.2 to 0.5 +/- 0.2 cm), regurgitant volume (69 +/- 47 to 69 +/- 56 ml) or effective regurgitant orifice area (0.5 +/- 0.4 to 0.5 +/- 0.6 cm2), individual patients exhibited marked directional variability. Specifically, VCW decreased in 16 patients (improved mitral regurgitation), remained unchanged in 7 patients and increased in 8 patients (worsened mitral regurgitation) with nitroprusside. Also, the VCW response to nitroprusside was concordant with changes in effective regurgitant orifice area and regurgitant volume, and was not different between dynamic and fixed orifice groups. CONCLUSIONS Contrary to the results from in vitro studies, VCW is not load independent in patients with mitral regurgitation caused by dynamic changes in the regurgitant orifice. The origin of mitral regurgitation does not predict accurately whether the regurgitant orifice is fixed or dynamic. Finally, short-term vasodilation with nitroprusside may significantly worsen the severity of mitral regurgitation in some patients.

Transesophageal Echocardiography Clinical Indications and Applications

Case: A 36 year-old woman without significant past medical history was admitted with left-sided hemiparesis. Imaging studies confirmed a right middle cerebral artery (MCA) stroke with normal carotid arteries. Transesophageal echocardiogram (TEE) showed right heart enlargement and a large secundum atrial septal defect (ASD) (Figure 1). Using TEE guidance, an ASD occluder device was placed without complication (Figure 2). Figure 1. This short-axis TEE view taken along the interatrial septum includes the left atrium, interatrial septum, and the right atrium. The color flow Doppler demonstrates left to right flow across an ASD. This figure can be viewed as a moving image online (see Movie I). Figure 2. An interatrial septal closure device is positioned across the ASD using TEE guidance. Both sides of the device are in position. The left atrium is at the top of the screen. No abnormal color flow was seen around the device. This figure may be viewed as a movie clip online (see Movie II). The use and indications for transesophageal echocardiography have expanded since its introduction over a decade ago.1,2 The suggested approach for a TEE examination is given in Table 1. As illustrated in the case above, TEE is used not only as a diagnostic tool but also as a monitoring adjunct for operative and percutaneous cardiac procedures (Table 2). The short distance between the transducer and the heart allows for the use of increased frequency transducers, yielding better spatial resolution and superior performance. Although major complications of TEE are rare (<0.02%), insertion and manipulation of the TEE probe can result in oral, esophageal, or pharyngeal trauma and arrhythmias, along with complications of conscious sedation. Because inaccurate acquisition and interpretation of images can lead to improper clinical decisions, experienced operators are essential to the success of TEE. View this table: TABLE 1. Suggested Approach …

Comparison of Vena Contracta Width by Multiplane Transesophageal Echocardiography With Quantitative Doppler Assessment of Mitral Regurgitation

Mitral regurgitation (MR) severity is routinely assessed by Doppler color flow mapping, which is subject to technical and hemodynamic variables. Vena contracta width may be less influenced by hemodynamic variables and has previously been shown to correlate with angiographic estimates of MR severity. This study was performed to compare mitral vena contracta width by multiplane transesophageal echocardiography (TEE) with simultaneous quantitative Doppler echocardiography in 35 patients with MR. The vena contracta width was measured at the narrowest portion of the MR jet as it emerged through the coaptation of the leaflets; it was identified in 97% of the patients. Vena contracta width correlated well with regurgitant volume (R2 = 0.81) and regurgitant orifice area (R2 = 0.81) by quantitative Doppler technique. A vena contracta width > or = 0.5 cm always predicted a regurgitant volume >60 ml and an effective regurgitant orifice area > or = 0.4 cm2 in all patients. A vena contracta width < or = 0.3 cm always predicted a regurgitant volume <45 ml and a regurgitant orifice area < or = 0.35 cm2. Thus, vena contracta width by multiplane TEE correlates well with mitral regurgitant volume and regurgitant orifice area by quantitative Doppler echocardiography and provides a simple method for the identification of patients with severe MR.

Dobutamine echocardiography in predicting improvement in global left ventricular systolic function after coronary bypass or angioplasty in patients with healed myocardial infarcts

The aim of this study was to determine whether low-dose dobutamine echocardiography (DE) could predict quantitative improvement in global left ventricular (LV) systolic function after coronary revascularization. Low-dose DE was performed in 71 consecutive patients with coronary artery disease and LV dysfunction. Successful coronary bypass surgery or angioplasty was performed in 44 patients, 37 of whom had a resting echocardiogram 1 to 3 months afterward. Group A consisted of 20 patients with contractile reserve during DE, and group B consisted of 17 patients without contractile reserve. As expected, regional wall motion score index (mean +/- SD) improved in group A (1.62 +/- 0.39 to 1.38 +/- 0.31, p < 0.01) but not group B (1.56 +/- 0.42 to 1.57 +/- 0.41, p = NS). In addition, LV ejection fraction (LVEF) improved after bypass surgery or angioplasty in group A (38 +/- 5% to 42 +/- 5%, p < 0.01), but not in group B (38 +/- 7% to 39 +/- 8%, p = NS). In group A, a significant linear correlation was observed between the number of segments with contractile reserve and the improvement in LVEF (r = 0.91, p < 0.0001). A good correlation also existed between the improvement in regional wall motion score index during dobutamine infusion and the improvement in LVEF after bypass surgery or angioplasty (r = 0.90, p < 0.0001). In conclusion, low-dose DE can be used to predict quantitative improvement in global LV systolic function after coronary bypass or angioplasty.

Aortic valve morphology: An important in vitro determinant of proximal regurgitant jet width by Doppler color flow mapping☆

In vitro and in vivo studies suggest that proximal aortic regurgitant jet width on Doppler color flow mapping predicts severity of aortic regurgitation. The influence of aortic valve morphology on proximal regurgitant jet width has not been studied. Despite equal cross-sectional area, differences in aortic valve morphology may influence regurgitant jet width and thus estimates of severity of aortic regurgitation. Aortic valve simulations representing degenerative, rheumatic and bicuspid valves as well as a circle in two cross-sectional areas (0.2 cm2 and 0.7 cm2) were placed in a flow model using two gradients (50 and 100 mm Hg) to produce simulated aortic regurgitant jets. Flow maps were obtained from parasternal and apical positions with color gain, frames per second, low velocity reject and depth held constant. The mean of three regurgitant jet widths for each shape, size and gradient were compared by three factor analysis of variance. Aortic valve morphology significantly affected regurgitant jet width in both parasternal and apical views (p = 0.0001 by analysis of variance) with bicuspid shapes producing regurgitant jet widths significantly different from all other shapes. Valve area also consistently significantly influenced proximal regurgitant jet width (p = 0.0001) in both views. Initial pressure gradient was less important. It is concluded that in an in vitro flow model aortic valve morphology introduces significant variability in the measurement of proximal regurgitant jet widths independent of orifice cross-sectional area. Estimates of severity of aortic regurgitation may therefore be influenced considerably by aortic valve morphology.

Intravascular ultrasound imaging of saphenous vein grafts in vitro: comparison with histologic and quantitative angiographic findings.

The ubiquity of coronary artery disease and the resultant widespread use of saphenous veins for coronary artery bypass surgery has stimulated considerable interest in the morphologic and pathophysiologic alterations these vessels undergo after implantation. This study was undertaken to determine the ability of intravascular ultrasound to identify and characterize abnormalities in saphenous vein grafts. Ten saphenous vein grafts excised at autopsy and nine saphenous vein segments harvested during coronary artery bypass surgery were examined with intravascular ultrasound imaging, quantitative coronary angiographic techniques and histologic analysis. Intravascular ultrasound lumen measurements were strongly correlated with quantitative coronary arteriographic measurements (r 0.91, SEE 0.5 mm). Wall thickness was significantly greater in the vein grafts after long-term implantation than in the freshly harvested veins (average thickness 1.4 +/- 0.5 vs. 0.7 +/- 0.2 mm, p less than 0.007); this finding correlated histologically with vein wall fibrosis. There was good correlation between ultrasound imaging and histologic analysis, with the ability to distinguish among normal intima, intimal hyperplasia, vein wall fibrosis and atheromatous plaque. Thus, this preliminary study demonstrates the ability of intravascular ultrasound to provide real-time cross-sectional images of saphenous veins and morphologic characterization of their walls. This modality may have important clinical applications, including the ability to detect serial changes in vein graft intimal hyperplasia and atherosclerosis.

Cardiovascular management in pregnancy: congenital heart disease.

The population of adults with CHD continues to expand,and thus the number of women with CHD who contemplate pregnancy or become pregnant is also growing. Mothers with low-risk defects can be managed by general cardiologist,whereas those with more complex defects should be managed by or with the assistance of ACHD cardiologists. It is important to acknowledge that all patients with CHD may have unique anatomy or physiology, despite their classification as having a simple, moderate, or complex defect. As such, clinicians evaluating these patients should have adequate knowledge and expertise when assessing patients risk for pregnancy,when performing imaging or hemodynamic studies, and when managing these patients during pregnancy. The American Board of Medical Specialties has recently recognized ACHD as a subspecialty of cardiovascular disease to treat the specialized needs of these patients in adulthood. ACHD experts can provide expertise in the management of specific defects or lesions, imaging techniques, prepregnancy risk assessment,and can manage these patients or comanage them with other medical providers during their pregnancy. Because many of these ACHD patients are lost to follow-up in adulthood, pregnancy represents a time when these patients seek medical care(and for some, represents a time of vulnerability and increased risk). This represents an opportunity to establish or reestablish care with ACHD specialists and to reestablish continuing long-term care for their CHD. Pregnancy also provides an opportunity to create partnerships between primary care physicians,adult cardiologists, and ACHD specialists to provide optimal care for these women throughout their lives.