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Biomedical subjects

H Feigenbaum

Publications and source records attributed to H Feigenbaum.

At least 37 records · Page 2Linked to original sources

Evolution of echocardiography.

The evolution of echocardiography has been interesting and dramatic. The technology has grown and has become an integral part of the practice of cardiology. As with all technology, there are advantages and disadvantages. The principal disadvantage is the fact that education and training are imperative to provide high-quality examinations and proper interpretations. In addition, many of the diagnoses are still qualitative and subjective. The principal advantage is the amazing versatility of this technology. The wealth of information that can be provided both noninvasively with a transthoracic examination and invasively with either transesophageal or intravascular ultrasound is tremendous. The anatomic and physiological data provided frequently give definitive diagnoses. If performed properly and for the right reason, this test should be very cost effective and should be a major asset in the coming era of medical cost containment. There are many technological advances that should enhance this information. With technology such as digital recordings, it is hoped that the clinicians will have better access to these data and will be more comfortable in interacting with this important diagnostic tool.

Analog-Digital Conversion↗

Transthoracic echocardiographic detection of coronary atherosclerosis.

Coronary atherosclerosis is a pathologic process that produces thickening of the walls of the coronary arteries to the point that flow through those vessels may be impaired. This study attempts to use transthoracic echocardiography to detect coronary atherosclerosis. Eighty-nine patients undergoing coronary angiography were examined with a broad-band ultrasonic transducer with a frequency between 3 and 5 MHz. A modified short axis examination was utilized to identify left main and proximal left anterior descending arteries. The examination was recorded digitally and displayed in a 32-cell, quad screen cine loop. Fifty-six of the 89 patients (63%) had obstructive coronary artery disease (CAD) (i.e, at least 1 vessel with 50% obstruction). There were 14 patients with CAD but no vessel had > or = 50% obstruction. Nineteen patients (21%) had angiographically normal arteries. The coronary echograms were judged qualitatively for brightness, uniformity, and persistence (defined as the ability to see segments of the artery walls in more frames than other segments). The length of the coronary artery visualized, the width of the left main coronary artery, and the width of the thickest segment of the coronary artery walls were quantitatively measured. More than 2 cm of the left coronary artery was seen in almost all patients. Segmental changes were noted in 52 of the 56 patients with obstructive CAD, 12 of the 14 patients with nonobstructive CAD, and 3 of the 19 patients with normal arteries. Persistence greatly enhanced the ability to judge the segmental changes. Forty-six patients with obstructive disease had wall thickness > or = 1.5 mm. Only 6 patients with nonobstructive coronary arteries had this wall thickness, and only 1 normal subject had thick walls. The ultrasonic findings were useful in predicting the presence or absence of coronary atherosclerosis to varying degrees of sensitivity and specificity based on the segmental findings and wall thickness measurements. The results of this study indicate that a transthoracic ultrasonic examination of the proximal left coronary artery could be a clinically valuable tool in the qualitative identification of coronary atherosclerosis.

Aged↗

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.

Adult↗

Assessment of hibernating myocardium by dobutamine stimulation in a canine model.

OBJECTIVES: The purpose of this study was to 1) develop an animal model of hibernating myocardium, and 2) evaluate the ability of dobutamine stimulation to detect hibernating myocardium using both qualitative and quantitative assessment of regional myocardial function. BACKGROUND: Left ventricular dysfunction may be due to chronic ischemia with or without myocardial infarction and may improve after coronary blood flow is enhanced by revascularization procedures. This condition has been coined "hibernating myocardium" and variably defined in recent years. The results of recent clinical studies suggest that dobutamine echocardiography may be useful for detecting viable myocardium in patients with left ventricular dysfunction. METHODS: Twenty-one dogs underwent initial operation. Sonomicrometer crystals were implanted, and baseline measurements of segment shortening and wall thickening (by echocardiography) were made. A coronary artery was ligated; the chest was closed; and measurements were repeated. Dobutamine was incrementally infused with determination of wall thickening and segment shortening at baseline and on days 3 and 7 and weeks 2 and 4 after coronary artery occlusion. Finally, the chest was reopened; the ligated vessel was bypassed; and measurements were repeated. RESULTS: Of the 10 dogs that completed the entire protocol, 7 had varying degrees of nontransmural myocardial infarction (group 1), and 3 had complete transmural myocardial infarction (group 2). In group 1, baseline function was significantly impaired compared with preligation function but increased during dobutamine infusion. When reperfused after 4 weeks, both wall thickening and segment shortening increased significantly. In group 2, significant changes were not seen during the dobutamine studies or after reperfusion. Myocardial perfusion during dobutamine infusion increased in group 1 but did not change in group 2. CONCLUSIONS: We demonstrated improvement in chronically dysfunctional myocardium after restoration of previously interrupted myocardial blood flow in dogs after nontransmural myocardial infarction, thus validating a canine model of hibernating myocardium. As assessed by two independent methods, dobutamine infusion identified hibernating myocardium in an animal model.

Animals↗

Dobutamine stress echocardiography: detection of coronary artery disease in patients with dilated cardiomyopathy.

OBJECTIVES: This study attempted to determine the safety and accuracy of dobutamine stress echocardiography for detection of coronary artery disease in patients with dilated cardiomyopathy. BACKGROUND: Detection of regional wall motion abnormalities at rest does not reliably distinguish ischemic from nonischemic cardiomyopathy. Previous studies have shown that dobutamine stress echocardiography safely and accurately identifies coronary artery disease in patients without dilated cardiomyopathy. METHODS: Seventy patients with dilated cardiomyopathy underwent dobutamine stress echocardiography. Echocardiograms were obtained at baseline and at low (5 to 10 micrograms/kg body weight per min) and peak doses of dobutamine. Rest and stress left ventricular wall motion scores were derived from analysis of regional wall motion. Fifty-four subjects underwent coronary angiography. RESULTS: Dobutamine infusion was terminated after achievement of the target heart rate or maximal protocol dose in 49 patients (70%), ischemia in 12 (17%), arrhythmia in 4 (6%) and side effects in 5 (7%). No patient had prolonged ischemia or sustained arrhythmia. Of those with angiographic studies, 40 had significant coronary artery disease (> or = 50% diameter stenosis). Use of the change in global wall motion score index from low to peak dose resulted in a sensitivity of 83% for dobutamine stress echocardiography and a specificity of 71% for detection of coronary artery disease. Sensitivity for detection of triple-, double- and single-vessel disease was 100%, 83% and 69%, respectively. CONCLUSIONS: Dobutamine stress echocardiography safely provides diagnostic information in patients with dilated cardiomyopathy. This technique has high sensitivity for multivessel coronary artery disease but only moderate specificity.

Adult↗

Risk stratification for restenosis after coronary angioplasty by means of exercise echocardiography.

To assess the prognostic contribution of exercise two-dimensional echocardiography in patients undergoing elective coronary angioplasty, 60 patients (44 males, 16 females, mean age 61 years) were enrolled in this study. The series included 31 patients with single-vessel disease, 23 with two vessel, and 5 with three vessel disease. After successful PTCA, they underwent stress echocardiographic testing either by treadmill (n = 23) or bicycle ergometry (n = 37), performed with digital continuous loop technique. A wall motion index (WMI) was calculated at rest and at peak stress. According to WMI values, the study population was divided into three groups: patients with normal WMI both at rest and stress (Group 1); patients with abnormal baseline WMI without change at stress (Group 2) and abnormal WMI diagnostic of stress-induced ischemia (Group 3). During the follow-up period, minimum of 1 year, 21 patients complaining of recurrent angina or chest discomfort, had repeat angiography: in 13 of these, typical restenosis of a previously dilated artery was found; 2 patients had progression of atherosclerotic plaque and in 6 the angiogram showed a good result of PTCA. Thirteen patients with restenosis or progressive disease underwent repeat PTCA. In this group, only 2 belonged to Group 1, 4 to Group 2, and 7 to Group 3. Thus, a linear correlation between the WMI value post-angioplasty and the clinical course could be documented (p = 0.001). Stress echocardiography was superior to stress ECG in both negative predictive value (88 and 77% respectively) and positive predictive value (73 versus 50%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Echocardiography and coronary artery disease.

Echocardiography is playing an increasingly important role in the management of patients with coronary artery disease. With the addition of new digital technology and new technological advances, such as multiplane transesophageal echocardiography and intravascular ultrasound, there is every expectation that this use of cardiac ultrasound will grow even more rapidly in the near future.

Acute Disease↗

Left ventricular dynamics during strenuous isometric exercise in marathon runners, weight lifters and healthy sedentary men: comparative echocardiographic study.

Global and segmental left ventricular dynamics during strenuous large-muscle isometric exercise were compared between endurance and static type professional athletes and sedentary men. Using a trunk dynamometer and supine echocardiography, only the weight lifters manifested increased (p < 0.01) wall thickness during both diastole and systole, resulting in decreased left ventricular volume at end systole. These group-related differences would suggest a causal relationship between chronic intensive weight-lifting training and efficient myocardial dynamics at the time of strenuous isometric exercise.

Adult↗

Symptoms, adverse effects, and complications associated with dobutamine stress echocardiography. Experience in 1118 patients.

BACKGROUND: The use of dobutamine stress echocardiography for the evaluation of coronary artery disease is rapidly expanding. New applications of the technique are being investigated in a wide variety of patients including those with advanced coronary artery disease. Despite its widespread use, the safety of dobutamine stress echocardiography has not been sufficiently documented. METHODS AND RESULTS: A consecutive series of 1118 patients undergoing dobutamine stress echocardiography for evaluation of known or suspected coronary artery disease form the basis of this report. Dobutamine stress testing was performed for evaluation of chest pain, risk assessment before noncardiac surgery, after recent myocardial infarction, or as a part of ongoing research protocols. Over the study period, the maximal dose of dobutamine used was increased from 30 to 50 micrograms/kg per minute, and atropine was used in 420 (37%) patients. There were no occurrences of death, myocardial infarction, or episodes of sustained ventricular tachycardia as a result of dobutamine stress testing. The major reasons for test termination were achievement of target heart rate in 583 patients (52.1%), maximum dose in 255 (22.8%), and angina pectoris in 142 (13%). The test was terminated in 36 (3%) patients because of noncardiac side effects including nausea, anxiety, headache, tremor, and urgency. Angina pectoris occurred in 216 (19.3%) patients. Sublingual nitroglycerin, a short-acting beta-blocker, or both types of medication were administered in 80 of these patients for relief of angina pectoris. None required intravenous nitroglycerin. A total of 736 (65%) patients had stable sinus rhythm throughout the test. The most common arrhythmias were frequent premature ventricular complexes (six or more per minute) in 172 patients (15%), and frequent premature atrial complexes in 86 (8%). There were 40 patients with nonsustained ventricular tachycardia. None had symptoms associated with the tachycardia, and only one received specific pharmacological treatment to prevent recurrence of the arrhythmia after the test was terminated. The patients who were evaluated after recent myocardial infarction and those who received atropine did not have a higher frequency of ventricular tachycardia compared with those without recent infarction and those not receiving atropine. CONCLUSIONS: Dobutamine stress echocardiography was safely performed using supplemental atropine and an aggressive dosing protocol. Noncardiac side effects were usually minor. Arrhythmias were well tolerated and rarely required treatment. In this study, serious complications from myocardial ischemia did not occur. Symptomatic ischemia was effectively treated with test termination, sublingual nitroglycerin, or short-acting beta-blockers.

Angina Pectoris↗

Low-dose dobutamine echocardiography detects reversible dysfunction after thrombolytic therapy of acute myocardial infarction.

BACKGROUND: Dysfunction after thrombolytic therapy of acute myocardial infarction (MI) may be reversible. Early after myocardial infarction, both reversible and irreversible injury may be manifested by regional wall motion abnormalities. Improved wall thickening during dobutamine infusion (dobutamine-responsive wall motion) may accurately identify reversibly injured segments. METHODS AND RESULTS: To determine whether dobutamine-responsive wall motion accurately detects reversible postischemic dysfunction irrespective of infarct location, multistage (baseline, 4 and 12 micrograms.kg-1.min-1, and peak) dobutamine echocardiography (DE) was performed within 7 days of thrombolytic therapy. Resting echocardiography was repeated > or = 4 weeks after MI, and reversible dysfunction was defined as improved wall motion. The accuracy of dobutamine-responsive wall motion was compared with that of signs of early reperfusion, non-Q-wave MI, and peak creatine kinase (CK). Sixty-three patients underwent DE without complications. Follow-up echocardiograms were done in 51 (81%) of these patients, and wall motion improved in 22 (41%). Dobutamine-responsive wall motion during all stages of DE was very specific for reversible dysfunction (90% to 93%) but sensitive (86%) only when hemodynamics were not altered (low dose, 4 micrograms.kg-1.min-1). Non-Q-wave MI and a low peak CK (< 1000 IU/mL) were also specific (89% to 93%) but less sensitive (64% [P = .16] and 55% [P < .05], respectively). Signs of early reperfusion did not identify postischemic dysfunction. Low-dose dobutamine-responsive wall motion and non-Q-wave MI independently identified reversible dysfunction, but only dobutamine-responsive wall motion was sensitive in all infarct locations. Non-Q-wave MI was sensitive only in anterior infarction. CONCLUSIONS: Multistage dobutamine echocardiography can be performed safely early after thrombolytic therapy. Low-dose dobutamine-responsive wall motion accurately detected reversible dysfunction in all infarct locations. Dobutamine-responsive wall motion and non-Q-wave infarction may be very useful for accurately identifying reversible dysfunction early after thrombolytic therapy for acute MI.

Adult↗

Exercise echocardiography.

Exercise echocardiography is a versatile, noninvasive diagnostic test that involves the recording and interpretation of 2-dimensional echocardiograms prior to, during, and after exercise. By analyzing and comparing wall motion at each stage, a prediction about the presence or absence of coronary artery disease can be made. The development of a wall motion abnormality is both sensitive and specific for the presence of a significant coronary stenosis. Changes in regional systolic function during exercise enable the clinician to distinguish between infarction and ischemia. Thus, the test yields information on the presence, extent, severity, and location of coronary artery disease. Echocardiography can be adapted to almost any form of stress, although treadmill or bicycle exercise are most commonly employed. An advantage of bicycle stress echocardiography is the opportunity to image during exercise, rather than relying on postexercise recording. This contributes to enhanced sensitivity, although false-positive results may increase due to the difficulties of analyzing wall motion during strenuous exercise. Exercise echocardiography increases the diagnostic accuracy of stress testing in a manner similar to radionuclide perfusion imaging. It is particularly useful in the setting of an ambiguous stress electrocardiography (ECG) or when a false-negative or false-positive result is suspected. It has been successfully applied to patients following revascularization and yields useful prognostic data in a variety of clinical situations. Exercise echocardiography is being increasingly utilized as a safe and accurate test in patients with known or suspected coronary artery disease.

Coronary Disease↗

Dobutamine stress echocardiography: correlation with coronary lesion severity as determined by quantitative angiography.

This study was performed 1) to determine the ability of dobutamine stress echocardiography to detect stenoses in individual coronary arteries by utilizing a new model of coronary artery distribution; 2) to evaluate its ability to detect coronary artery stenosis with a minimal lumen diameter less than 1 mm; and 3) to correlate the heart rate at which a positive test result occurs with the severity of coronary artery disease. Eighty-five patients were identified who underwent both dobutamine stress echocardiography and quantitative coronary angiography. During incremental infusion of dobutamine, two-dimensional echocardiograms were obtained at rest, during low and peak stress and after stress. Echocardiograms were interpreted with use of a modified 16-segment model with an anteroinferior overlap scheme. The overall sensitivity of the technique for the detection of significant coronary artery disease (diameter stenosis greater than or equal to 50%) was 95%; specificity was 82% and accuracy 92%. The sensitivity for detection of individual coronary artery lesions did not differ significantly (p greater than 0.05) in the three major coronary artery distributions (79% left anterior descending, 70% left circumflex, 77% right coronary artery). Among 35 stenoses with a minimal lumen diameter less than 1 mm, the test result was positive in 30 (86%). Test results were correctly positive for 88%, 82% and 86% of stenoses in the left anterior descending, left circumflex and right coronary artery distributions, respectively. Multivessel disease was present in 11 of 16 patients with normal wall motion at rest who developed a wall motion abnormality at a heart rate less than 125 beats/min. The incidence of multivessel disease was statistically higher in patients with positive findings on a dobutamine stress echocardiogram at a heart rate less than or equal to 125/min. In conclusion, dobutamine stress echocardiography has high sensitivity and specificity for the detection and localization of coronary artery disease. Detection of stenosis in individual coronary arteries is improved in those lesions with a minimal lumen diameter less than 1 mm. Patients with a positive test result at a heart rate less than or equal to 125 beats/min have a high likelihood of multivessel coronary artery disease.

Adult↗

Distinguishing ischemic cardiomyopathy from nonischemic dilated cardiomyopathy with coronary echocardiography.

Transthoracic echocardiographic examination of the proximal left coronary system was performed in 59 patients who had dilated cardiomyopathy to determine if this technique could distinguish between ischemic and nonischemic dilated cardiomyopathy. With use of annular array transducers (3.5 or 5 MHz) and digital image processing, echocardiographic visualization of the coronary arteries was successful in 55 (93%) of 59 patients. As assessed by coronary angiography, 32 subjects had ischemic cardiomyopathy and 27 had nonischemic cardiomyopathy. Twenty-seven (84%) of the 32 patients who had coronary artery disease and 24 (89%) of the 27 patients with nonischemic cardiomyopathy were correctly identified. The accuracy of coronary echocardiography was 86% in the entire study group and 93% when patients with inadequate studies were excluded. All subjects who had ischemic cardiomyopathy had evidence of disease by coronary echocardiography or segmental wall motion abnormalities. Multivariate analysis permitted correct classification of 93% of all subjects based on the results of the coronary echocardiogram, evaluation of segmental wall motion and a history of prior myocardial infarction. The correct diagnosis was made in 86% when the results of coronary echocardiography were excluded from analysis using all other echocardiographic and clinical variables. Transthoracic coronary echocardiography can be performed with a high degree of success in patients with dilated ventricles and the technique can reliably distinguish between ischemic and nonischemic dilated cardiomyopathy.

Cardiomyopathy, Dilated↗

Dobutamine stress echocardiography as a predictor of cardiac events associated with aortic surgery.

Two-dimensional echocardiography can detect regional wall motion abnormalities resulting from myocardial ischemia produced by dobutamine infusion. In 60 patients undergoing elective aortic surgery (27 with aneurysms, 33 with occlusive disease), we evaluated the ability of dobutamine stress echocardiography to predict perioperative cardiac events. Echo images were obtained at rest and during incremental dobutamine infusion to a peak dose of 50 micrograms/kg/min, unless another test end point was reached (angina, heart rate greater than or equal to 85% of age-predicted maximum, significant ST segment depression, or new stress-induced wall motion abnormalities). Dobutamine stress echocardiography results were stratified as follows: group I, no wall motion abnormalities; group II, resting wall motion abnormalities unchanged with stress; group III, stress-induced worsening of resting wall motion abnormalities; group IV, new-onset wall motion abnormalities with stress. Twelve cardiac events occurred within the first 30 postoperative days: three cardiac deaths (5%), six nonfatal myocardial infarctions (10%), two patients with unstable angina (3.3%), and one patient with asymptomatic elevation of creatine phosphokinase MB isoenzymes without electrocardiographic changes (1.7%). Eleven events occurred in the 38 patients with an abnormal dobutamine stress echocardiograph (groups II to IV); in contrast, only one of 22 patients with a normal dobutamine stress echocardiograph (group I) had a cardiac event. These event rates (29% vs 4.6%) differed significantly (p less than 0.025). Dobutamine stress echocardiography is a new, safe, rapid, relatively low cost, noninvasive, nonexercise cardiac stress test for risk stratification before major vascular surgery.

Aged↗

Digital echocardiography in myocardial infarction.

Probably the most under-utilised application of echocardiography is in patients with coronary artery disease (CAD). This under-utilisation is striking since echocardiography can be very valuable in evaluating the natural history and therapy of CAD. One reason why echocardiography is not being utilised to its fullest is because of the reliance on videotape to record and display echocardiograms. This medium is time consuming and inconvenient for clinicians to review studies, it is not ideal for detecting subtle wall motion abnormalities, and videotape is impractical for comparing serial studies. Recording and storing echocardiograms on a digital medium overcomes these difficulties. Digital cine loops of single cardiac cycles provide great versatility. Multiple views or studies can be displayed simultaneously, subtle changes in wall motion are more easily detected and different views, or serial studies, can be readily compared. Such images can be displayed on computers on the ward or in the coronary care unit (CCU) and be available 24 hours a day, seven days a week at the convenience of the clinician. One does not need to find a recording on a two hour videotape, which may be in the ultrasound instrument, and one can view the exam in 30 sec instead of 5 to 10 min. Regional and global left ventricular function is one of the most important manifestations of CAD. With new therapeutic efforts at restoring myocardial function and limiting infarct expansion, assessing LV function is more important than ever. Digital echocardiography is an extremely practical and convenient way for clinicians to obtain this information.

Echocardiography↗

Echocardiography in the management of mitral valve prolapse.

Echocardiography plays a major role in the management of patients with mitral valve prolapse (MVP). The technique has greatly enhanced our understanding of the pathophysiology, epidemiology and natural history. There are major and minor echocardiographic diagnostic criteria for prolapse. Major criteria involve the mitral leaflets and include late systolic posterior displacement on M-mode, bulging into the left atrium on 2D long-axis (LAX) view, and thickening and redundancy of the leaflets. Minor criteria include holosystolic posterior prolapse on M-mode, bowing of the mitral leaflets into the left atrium (LA) in the apical 2D views, and late systolic mitral regurgitation on the Doppler echogram. Any of the major criteria should be sufficient to make the diagnosis. One or two minor criteria without a major sign would be questionable. The degree of thickening and redundancy and the presence and quantitation of mitral regurgitation influence prognosis. Echocardiography is also helpful in identifying complications such as endocarditis and ruptured chordae. An echocardiogram may not be necessary for the diagnosis, but it is helpful for prognosis and as a baseline for possible future changes. The frequency of follow-up echocardiograms should be determined by clinical findings. When mitral regurgitation is present, then one should follow LA and left ventricular size and function. Transoesophageal echocardiography may be desirable for better definition of vegetations or flail leaflets and is frequently used to monitor surgical repair.

Echocardiography↗

Exercise echocardiography.

Exercise testing is an indispensable component of clinical cardiology. Latent disease or the full extent of a problem may not be apparent on a resting examination. Some form of stress is frequently necessary, especially in patients with coronary disease, to appreciate whether a patient has stress-induced ischaemia as manifested by exercise-induced chest discomfort, a drop in blood pressure or electrocardiographic changes of ischaemia. Unfortunately as with every test ECG and clinical monitoring have limitations. Patients may have ischaemia without pain, ECG changes may be non-specific, a resting abnormal ECG has limited value, and the location and amount of ischaemic muscle is not directly assessed. Monitoring the echocardiogram adds significant additional information to routine stress testing. By visualising the myocardium in the exercising individual, it is possible to assess a fundamental manifestation of ischaemia, regional wall motion abnormalities. This information helps identify the vessels and the amount of muscle involved. In addition resting wall motion abnormalities may detect clinically silent infarction or hibernating myocardium. Direct visualisation of the exercising heart provides an improved understanding of a patient's cardiac status. The technique is particularly useful in evaluating revascularisation procedures. Advances in instrumentation have reduced or eliminated many of the technical difficulties with obtaining and interpreting exercise echocardiograms. This examination has become an extremely useful adjunct to routine stress testing.

Coronary Disease↗