John R. Bates

Evaluation using dobutamine stress echocardiography in patients with insulin-dependent diabetes mellitus before kidney and/or pancreas transplantation

The purpose of this study was to examine the ability of dobutamine stress echocardiography to stratify patients with juvenile onset, insulin-dependent diabetes mellitus who are being considered for kidney and/or pancreas transplantation, into high-or low-risk groups for future cardiac events. Fifty-three such patients underwent dobutamine stress echocardiography before kidney and/or pancreas transplantation. Cardiac events, including cardiac death, nonfatal myocardial infarction, unstable angina, pulmonary edema, and need for coronary revascularization, occurring between the time of the dobutamine stress echocardiogram and the last patient follow-up contact were retrospectively identified. Twenty patients 938%) had an abnormal dobutamine stress echocardiogram. Eleven patients had 15 cardiac events over a mean (+/- SD) follow-up period of 418 +/- 269 days. Event rates were 45% among those with an abnormal, versus 6% among those with a normal dobutamine stress echocardiogram (p = 0.002). The result of the dobutamine stress test independently predicted prognosis in a multivariate analysis (p = 0.003, odds ratio = 12.7). We conclude that dobutamine stress echocardiography accurately stratifies patients with juvenile onset, insulin-dependent diabetes being considered for kidney and/or pancreas transplantation for risk of future cardiac events.

Evaluation of Patterns of Perfusion and Metabolism in Dobutamine-Responsive Myocardium

OBJECTIVES We investigated the patterns of perfusion and metabolism in dysfunctional myocardium whose contractility improved with dobutamine. BACKGROUND Clinical studies have suggested that dobutamine echocardiography can identify hibernating myocardium, but laboratory studies suggest that reduced perfusion limits the response to dobutamine. METHODS Twenty-five patients with coronary disease and ventricular dysfunction underwent low (5 and 10 micrograms/kg body weight per min) and high dose (maximum of 50 micrograms/kg per min) dobutamine echocardiography and positron emission tomography (PET) using nitrogen-13 (N-13) ammonia and fluorine-18 fluorodeoxyglucose (FDG) for imaging of perfusion and metabolism. Wall motion and tracer uptake were scored in 16 left ventricular segments. RESULTS Perfusion and metabolism were normal in 56.4%, mildly reduced in 29.1% and mismatched (reduced perfusion, preserved FDG uptake) in 14.5% of dysfunctional segments viable on PET. Wall motion improved with dobutamine in 89 dysfunctional segments (62 at low dose, 27 only at peak dose), and 86 of these (97%) were viable on PET. Improvement in wall motion with dobutamine was more common in segments with normal perfusion and metabolism (56.5%) than in those with mildly reduced tracer uptake (28.5%, p < 0.001) and those with mismatch (32%, p = 0.03). All the segments with a biphasic response were supplied by vessels with > or = 70% stenosis, and 88% had normal perfusion and metabolism. CONCLUSIONS The majority of viable segments with rest dysfunction had normal perfusion and metabolism, suggesting that myocardial stunning was common. Improvement of wall motion at low and high doses of dobutamine was highly correlated with myocardial viability on PET and was more common in myocardium with normal perfusion. A biphasic response to dobutamine identified segments with normal perfusion and metabolism supplied by severely diseased vessels.

Color Coding of Digitized Echocardiograms: Description of a New Technique and Application in Detecting and Correcting for Cardiac Translation

Color coding is a new software application for digitized echocardiograms that displays a reference image of end diastole throughout the cardiac cycle. With color-coded digitized echocardiograms, we determined the frequency of, and corrected for cardiac translation in 21 bicycle stress echocardiograms in patients who were known to be without significant coronary artery disease or wall motion abnormalities. Translation was present in 4%, 40%, and 74% of rest, postexercise, and peak exercise images, respectively, and was noted most frequently in the apical views, 59% of four-chamber views and 40% of two-chamber views. Interobserver and intraobserver agreement for detection of translation was 81% and 86%, respectively. Translation was corrected by shifting digitized images to eliminate transverse displacement of the mitral valve anulus and restore normal basal-to-apical shortening. Ventricular contraction was assessed as normal in 92% of the images in which correction for translation was performed. In the remaining images, poor image quality (3%) and apparent wall motion abnormalities (5%) prevented the studies from being graded as normal. We conclude that color coding of digitized echocardiograms is a useful new technique that can be applied to detect and correct for cardiac translation.

Dynamic Three-Dimensional Echocardiographic Reconstruction of Congenital Cardiac Septation Defects

Abstract. Dynamic three-dimensional echocardiographic reconstructions of 27 cardiac septation defects were performed in 19 sedated infants and children. Using a subxiphoid rotational scanning approach, complete visualization of the entire shape and breadth of the defect was attained in 11 of 16 ventricular septal defects and 9 of 11 atrial septal defects. This technique enabled the operator to cut slices from the three-dimensional block of echocardiographic data in order to present septation defects in a region- or lesion-oriented fashion. Poor baseline two-dimensional image quality and certain small septation defects that were readily obscured by nearby structures led to inadequate three-dimensional reconstructions. The application of dynamic three-dimensional echocardiography for assessment of cardiac septation defects uniquely provided (1) the ability to present en face views of atrial and ventricular septal defects; and (2) a means by which intracardiac anatomy can be displayed in a region- and lesion-oriented fashion for interventional and surgical planning purposes.

A systematic approach to echocardiographic image acquisition and three-dimensional reconstruction with a subxiphoid rotational scan☆

Rotational scanning from the subxiphoid position is an image acquisition technique used for reconstruction of dynamic three-dimensional echocardiographic images in infants and small children. The orientation of the heart within the three-dimensional data set is variable and dependent on the image plane at which rotational scanning was initiated. We describe an image acquisition technique that standardizes the orientation of the heart within the three-dimensional data set, thereby permitting a systematic approach to the reconstruction of three-dimensional renderings. Thirteen infants and small children with congenital heart disease were studied by this approach. Illustrative examples are provided. The average time required to derive a three-dimensional rendering was 37 +/- 9 minutes. We conclude that subxiphoid rotational scanning by a systematic approach to image acquisition and reconstruction can be applied successfully to the derivation of three-dimensional renderings of congenital cardiac defects.

Acute Cardiac and Neurologic Decompensation in a High School Athlete

A 19-year-old African American man presented to a local emergency room with atrial flutter, dysarthria, and left-sided hemiparesis. He was previously healthy and a successful high school athlete. The patient decompensated and went into cardiac arrest. Two-dimensional echocardiography revealed biventricular dilation, severe systolic dysfunction, and a spongy myocardial appearance. Postmortem examination was diagnostic of biventricular noncompaction. Such a fulminant presentation of isolated ventricular noncompaction in a previously healthy and physically fit individual has not yet been described.

Deformation Imaging: A New Season for the Athlete's Heart

Echocardiography has played a fundamental role in the description of cardiac adaptation to exercise. The ability to quantify ventricular size, wall thickness, systolic function, and ventricular filling properties has servedtocharacterizeremodeling attributedtoathletictraining.While most forms of athletic training result in an increase in left ventricular (LV) mass with preservation of systolic function and enhancement of diastolic filling, endurance training typically results in eccentric hypertrophy whereas resistance training promotes concentric hypertrophy. 1 Though most sporting activities actually consist of a mixture of endurance and resistance exercise, these constructs have been helpful to distinguish physiologic adaptation, the ‘‘athlete’s heart,’’ from pathologic entities such as hypertrophic cardiomyopathy. 2 Deformation imaging has advanced our understanding of myocardial mechanics and consequently the cardiac adaptation to exercise. In the evaluation of the athlete’s heart, the focus has been on structure-chamber size, wall thickness, patterns of hypertrophy, and the exclusion of occult structural abnormalities. Diastolic parameters have been useful to confirm normal filling and differentiate between physiologic and pathologic hypertrophy. The assessment of systolic function has typically been with global measures such as ejection fraction or fractional shortening. Now, the capacity exists to assess myocardial function more directly by measuring longitudinal, circumferential, and radial strain aswell as twist(the basalto apical difference in LV rotation) in both systole and diastole. 3 These indices, while numerous and at times complex, promise to unlock the basic functional changes in the myocardium that occur with training and during exercise. The study by Lee and colleagues in this issue of the Journal 4 adds to our understanding of the cardiac adaptation to endurance training in healthy middle age males. The authors found that endurance training results in the ability to enhance systolic twist during exercise as well as the ability to augment early diastolic filling by maintaining the time to peak untwist velocity. These properties were similar to young, healthy controls but dissimilar to healthy untrained age matched controls. This is the first description of such findings in middle aged endurance athletes and adds to a growing literature describing the effects of athletic training on myocardial mechanics. Enhancement of systolic twist has been demonstrated in athletes at rest, but the findings have not been completely consistent. A study of university rowers following a ninety day period of endurance training demonstrated significant increases in peak LV systolic twist as well as peak early diastolic untwisting rate. 5 A study comparing young cyclists, soccer players, and basketball players to controls demonstrated an increase in apical twist only in the cyclists. 6 LV torsion at rest was compared in soccer players to controls and the soccer players were found to have reduced twist and basal and apical radial strain. 7 In a study of cyclist compared to controls, apical radial strain and LV torsion were lower in the cyclists! 8 In the current study, systolic twist values at rest were not significantly different between the controls and trained middle aged males. The heterogeneity of these findings is difficult to explain. It appears that training can enhance systolic twist, but that when compared with controls in the resting state, systolic twist may not always differentiate the athlete’s heart. The specific athletic endeavor as well as the intensity and duration of training may play an important role in the magnitude of effect on systolic twist at rest. Other systolic indices of deformation have been shown to be accentuated in the athlete’s heart at rest. In an earlier study of university rowers, following a ninety day period of endurance training, an increase in peak systolic tissue velocities, radial strain, and longitudinal strain with a base to apex gradient was noted. Circumferential strain increased in the LV free wall but decreased in the septum. 9 Acomparisonofprofessional soccerplayerstocontrols andpatients withhypertrophic cardiomyopathy demonstrated significantly higher radial and transverse strain, but lower longitudinal strain in the soccer players than controls. Compared to patients with hypertrophic cardiomyopathy, soccer players had higher values for radial, transverse, and circumferential strain. 10 The relationship between the various deformation indices is complex. In disease states, for instance, circumferential strain and twist may compensate for diminished longitudinal strain. 3 Given that a subset of the available deformation indices are evaluated in the studies of athletes, it is difficult to know if certain indices are up or down regulated due to an enhanced or diminished effect of other indexes. The effect of exercise on deformation indices has typically demonstrated an augmented reserve in trained athletes. The current study demonstrates the ability of endurance training to augment systolic twist during sub maximal exercise. Donal and colleagues compared young ( 50 years) male athletes to age matched controls and found that both athletic groups had higher LV mass and LV volumes. Stroke volume and global longitudinal strain during exercise was greater in the athletic groups, with the global strain during exercise being highest in the younger athletes. 11 Unfortunately, the absence of a young, trained group in Lee’s study did not allow comparison of the magnitude of the training effect between young and middle aged subjects, as was possible in Donal’s study. In a study comparing elite soccer players with controls, despite similar strain values at rest, mid-ventricular and apical strain were augmented and significantly higher in athletes following hand grip exercise. 12