Search

During the past twenty years, there has been a dramatic increase in obesity and the cardiometabolic syndrome (CMS). In the United States alone, there are an estimated 42 million persons affected by CMS.1 In addition to complications from diabetes and hypertension, this population is at risk for the development of both ischemic and non-ischemic heart failure.2 Although it is fairly well accepted that obesity and other aspects of CMS contribute to left ventricular (LV) remodeling and diastolic dysfunction, controversy does exist as to the effects of CMS on systolic function.2 This is partly due to the fact that obesity is associated with an increase in plasma volume.2 Thus, any load-dependent measures of systolic function, e.g., cardiac output, are necessarily affected by alterations in volume as well as contractility. Different methods for indexing LV systolic function measures in obese subjects may also affect systolic function results. For example, cardiac output may be increased in obesity but when indexed for body surface area, cardiac index may be low. Thus, newer, more load-independent noninvasive methods are necessary for better characterizing LV systolic function. Tissue Doppler imaging (TDI), an echocardiographic method previously described in the Images in CMS section of the Journal of the Cardiometabolic Syndrome, is considered to be relatively load-independent.3 Although, TDI is relatively easy to perform and measure, it does have some limitations. TDI provides a longitudinal assessment of the function of an entire wall rather than of a segment, so localization of the segmental wall motion abnormalities using TDI is limited.4 Additionally, because it is a Doppler-derived parameter, it is necessarily angle-dependent, and so TDI-derived measures of function are angle-dependent. A new echocardiographic technique called strain imaging, overcomes some of the limitations of TDI. Like TDI, strain imaging is thought to be relatively load-independent, but strain imaging has other advantages as well. Strain imaging allows for segmental wall motion quantification and (when quantified using speckle tracking) is not angle-dependent. In order to explain this technique it is first important to define “strain” as it pertains to LV systolic function. Strain means deformation and is calculated as the change in length divided by the original length.4 As such, strain is dimensionless and typically represented as a negative fractional or percentage change in dimension. Since LV contraction in systole causes LV deformation (strain), strain is a measure of contractility.4 (The rate at which the LV deforms may also be measured echocardiographically and is termed “strain rate,” but this imaging article will focus on strain). LV contraction is a three-dimensional process that involves radial and longitudinal cardiac muscle fibers. As longitudinal fibers shorten the ventricle, radial fibers squeeze in and twist in a clockwise direction at the base and counter-clockwise at the apex. The result is an efficient wringing motion comprising of radial, circumferential, and longitudinal contractility. Measuring regional strain is used for the detection and quantification of segmental wall motion abnormalities, and myocardial strain derangements have been correlated with ischemia.5 Regional strain was first quantified non-invasively in humans using magnetic resonance imaging. While this method is accurate, it is costly, not widely available, and has limited temporal resolution. Strain may also be quantified using echocardiography using a Doppler-derived method.6 However, this technique, while useful for quantification of segmental wall systolic function is angle-dependent.

Background The presence of an abnormal late-peaking left ventricular velocity contour, detected by Doppler echocardiography, has been reported in patients with hypertrophic cardiomyopathy, left ventricular hypertrophy, and aortic stenosis. Methods and Results To evaluate the clinical and prognostic significance of this characteristic Doppler finding, we studied a group of patients ( n = 57) with isolated AS undergoing aortic valve replacement. Patients were divided into two groups according to the presence ( n = 28) or absence ( n = 29) of a hypertrophic late-peaking left ventricular velocity pattern. There were no differences between the groups with respect to age, sex, and presence of coronary artery disease. Peak preoperative aortic valve gradients were similar in both groups (70 vs. 67 mm Hg; p = not significant). The postoperative course of patients with abnormal late-peaking ventricular velocity contour was complicated by a higher incidence of arrhythmias (80% vs. 38%; p = 0.0002). Hypotension and the use of inotropic support were significantly more common in the group with abnormal late-peaking ventricular velocity contour (79% vs. 24%; p = 0.0001 and 76% vs. 26%; p = 0.0001, respectively). Hemodynamically, patients with a late-peaking velocity pattern exhibited a higher pulmonary diastolic pressure (16 ± 3 vs 12 ± 2 mm Hg; p = 0.0003), wedge pressure (12 ± 4 vs 10 ± 2; p p = 0.0001) and lower cardiac index (2.4 ± 0.3 vs 2.9 ± 0.4; p = 0.0001). Conclusions An abnormal late-peaking ventricular velocity contour pattern appears to be a high risk marker for postoperative complications in patients undergoing aortic valve replacement. Routine Doppler evaluation in patients undergoing valve replacement for AS may therefore identify these patients. (Am Heart J 1998;136:71-7.)

Variations in reported sensitivity of myocardial perfusion scans or wall motion abnormalities during pharmacologic stress with intravenous adenosine and dipyridamole may be caused by differences in myocardial oxygen demand or myocardial blood flow redistribution induced by each agent. To investigate the physiologic correlates of functional abnormalities during pharmacologic stress testing, regional myocardial blood flow (radiolabeled microsphere technique) and left ventricular segmental wall thickening (quantitative two-dimensional echocardiography) were measured in 9 dogs with an open chest model of critical stenosis of the left circumflex coronary artery. Data were obtained at baseline and peak drug infusion for intravenous adenosine (0.42 mg/kg over a 3-minute period) and for intravenous dipyridamole (0.56 mg/kg over a 4-minute period). Adenosine and dipyridamole induced regional flow abnormality in 7 (77%) of 9 dogs. Myocardial segments with decreased endocardial/epicardial flow ratio were similar for both agents (2.9 +/- 1.8 vs 2.7 +/- 1.3, p = [NS]). Segments with myocardial flow heterogeneity (ratio of endocardial flow to control left anterior descending/left circumflex endocardial flow) were similar for both agents (2.7 +/- 0.9 vs 2.3 +/- 1.0, p = NS). Adenosine-induced wall thickening abnormality (77% vs 55% with dipyridamole) correlated with regional flow abnormality. Significantly lower mean arterial pressure (53 +/- 1.7 mm Hg vs 64 +/- 1.9 mm Hg, p < 0.01) and more prolonged drug effect (18 +/- 6.4 min vs 3 +/- 1.4 min, p < 0.001) were seen for dipyridamole compared with adenosine. Adenosine induces regional flow abnormality similar to dipyridamole but with less hemodynamic perturbation, and adenosine-induced wall thickening abnormality more closely parallels regional flow abnormality.

Background The study evaluates whether Optison used during dobutamine stress echocardiography (DSE) will improve endocardial border definition and whether this will translate to an improvement in sensitivity and specificity of the test in patients with poor echocardiographic windows. DSE is extremely valuable in the workup of patients with coronary artery disease. The test is limited in patients with suboptimal endocardial border visualization. Frequent studies have demonstrated improved endocardial border visualization with intravenous contrast agents at rest. Methods and Results We studied 229 patients: 112 had good rest echocardiography with no contrast and 117 had poor rest echocardiography with Optison injection during DSE. Percentage of endocardial border visualization, wall thickening, sensitivity, and specificity were compared in both groups, as was interobserver variability. Both groups were matched with respect to age, percentage of previous myocardial infarctions, resting wall motion abnormality, percentage of coronary stenosis, and number of diseased coronary arteries. Optison significantly improved endocardial border visualization, especially at peak stress. The ability to measure wall thickening was significantly higher in the contrast DSE group with suboptimal images versus the noncontrast group with optimal images (89% ability to measure wall thickening vs 71%, P =.01). This resulted in a comparable sensitivity (79% vs 71%, P = not significant [NS]), specificity (76% vs 82%, P = NS), and diagnostic accuracy (80% vs 76%, P = NS). Agreement on test interpretation was higher among 3 observers in contrast DSE versus noncontrast DSE groups (79% vs 69%, P =.01). Conclusions In patients with poor echocardiographic windows, the use of Optison during DSE improves endocardial border visualization, which translates to a comparable sensitivity and specificity to noncontrast DSE tests in patients with good echocardiographic windows. (Am Heart J 2001;142:908-15.)

To characterize coronary blood flow velocity parameters and to determine the relation among velocity, volumetric flow, and vascular resistance in awake human beings, we performed paired proximal and distal velocity measurements in 28 angiographically normal coronary arteries. Mean velocity, peak velocity, diastolic-to-systolic velocity ratio, and diameter and cross-sectional area of proximal and distal arteries were determined and coronary flow and vascular resistance computed. Mean velocity and coronary vasodilator reserve were similar for all three native arteries and were preserved from proximal to distal segments. Volumetric flow decreased from proximal to distal segments. The demonstrated inverse and curvilinear (polynomial) relation between volumetric flow and vascular resistance agrees with theoretical and animal models of coronary physiologic characteristics and suggests a nadir of coronary vascular resistance below which coronary flow no longer increases.

Aortic regurgitation is most frequently assessed noninvasively by Doppler echocardiography by use of continuous wave and Doppler color flow mapping. To compare both Doppler methods, 161 patients who had undergone cardiac catheterization and complete echocardiographic studies were studied. The continuous wave parameters analyzed included the slope of the diastolic deceleration and the pressure half-time of the regurgitant jet. From color flow Doppler, conventional parameters such as JH and its ratio to LVOH, JASA and its ratio to LVOA, and the regurgitant JA and its ratio to the LVA were obtained. The JH/LVOH was the color flow parameter that best correlated with angiography (r = 0.91). A ratio ofor = 25% was used to predict mild aortic regurgitation with 96% accuracy. A ratio ofor = 40% was also used to predict severe aortic regurgitation (3 to 4+) with 96% accuracy. Absolute JH at the origin of the regurgitant jet was the second best color flow parameter that correlated with angiography (r = 0.89). When continuous wave-derived slope was used, a significant overlap among different degrees of aortic regurgitation was observed. Predictive accuracy for mild aortic regurgitation was 70% by using a slope2 m/sec2 and 86% for severe aortic regurgitation when using a slope3 m/sec2. In conclusion, color flow Doppler appears to be superior to continuous wave Doppler in the assessment of aortic regurgitation. The JH/LVOH appears to be the best color parameter for quantifying aortic regurgitation. The measurement of the absolute JH at its origin appears to be the simplest and most practical method for assessing the degree of aortic regurgitation.

Context.—Left ventricular (LV) hypertrophy is a common problem among elderly patients with isolated systolic hypertension (ISH), but the effect of treatment of ISH on LV mass is not known.Objective.—To assess the ability of antihypertensive drug treatment to reduce LV mass in ISH.Design.—Echocardiographic Substudy of the Systolic Hypertension in the Elderly Program (SHEP).Patients.—A total of 104 participants at the St Louis SHEP site who had interpretable baseline echocardiograms, 94 of whom had 3-year follow-up echocardiograms.Intervention.—The SHEP participants were randomized to placebo or active treatment with chlorthalidone (12.5-25 mg/d), with atenolol (25-50 mg/d) added if necessary to maintain goal blood pressure.Main Outcome Measure.—Change in LV mass assessed by echocardiography.Results.—Minimum follow-up was 3 years. In the active treatment group, 91% and 80% of subjects were receiving treatment with chlorthalidone alone by the end of years 1 and 3, respectively. The LV mass index was 93 g/m2 in the active treatment group and 100 g/m2 in the placebo group (P