PubMed Health⌕ Search

Biomedical subjects

T H Marwick

Publications and source records attributed to T H Marwick.

At least 127 records · Page 7Linked to original sources
PubMed1995

Angiographic and prognostic implications of an exaggerated exercise systolic blood pressure response and rest systolic blood pressure in adults undergoing evaluation for suspected coronary artery disease.

OBJECTIVES: This study was designed to assess the angiographic and prognostic implications of an exaggerated systolic blood pressure response to exercise ("exercise hypertension") in adults undergoing evaluation for suspected coronary artery disease. BACKGROUND: The clinical implications of exercise hypertension are unclear. METHODS: Subjects for this prospective cohort study were derived from a consecutive sample of 9,608 adults who were referred for treadmill testing and who augmented their systolic blood pressure by at least 10 mm Hg. There were 594 subjects who underwent coronary angiography within 90 days of treadmill testing. Exercise hypertension was defined as a peak exercise systolic blood pressure > or = 210 mm Hg in men and > or = 190 mm Hg in women. Severe angiographic coronary disease was defined as left main coronary artery disease (> or = 50% diameter stenosis), three-vessel disease (> or = 70% diameter stenosis) or two-vessel disease with > or = 70% diameter stenosis of the proximal left anterior descending coronary artery. All-cause mortality was assessed during a follow-up period of approximately 2 years. RESULTS: Exercise hypertension was present in 196 subjects (33%). Severe coronary disease was less common in subjects with exercise hypertension (14% vs. 25%, odds ratio 0.51, 95% confidence interval [CI] 0.32 to 0.81, p = 0.004). Exercise hypertension remained associated with a lower rate of severe coronary disease even after adjusting for rest hypertension, age, gender, exercise capacity and other possible confounders. During the follow-up period, there were 23 deaths; only 2 occurred in the group with exercise hypertension. After adjusting for severity of coronary disease, exercise hypertension remained associated with a lower mortality rate (adjusted relative risk 0.20, 95% CI 0.05 to 0.84, p = 0.03). CONCLUSIONS: In adults evaluated for coronary artery disease, exercise hypertension is associated with a lower likelihood of angiographically severe disease and a lower adjusted mortality rate.

Blood Pressure↗
PubMed1995

Exercise echocardiography is an accurate and cost-efficient technique for detection of coronary artery disease in women.

OBJECTIVES: This study compared the accuracy and cost implications of using exercise echocardiography and exercise electrocardiography for detection of coronary artery disease in women. BACKGROUND: The specificity of exercise electrocardiography in women is lower than in men. Exercise echocardiography accurately identifies coronary artery disease in women, but its utility in place of exercise electrocardiography is unclear. METHODS: One hundred sixty-one women without a previous Q wave infarction underwent exercise echocardiography and coronary angiography. Positive findings were a new or worsening wall motion abnormality on the exercise echocardiogram and ST segment depression > 0.1 mV at 0.08 s after the J point on the exercise electrocardiogram (ECG). RESULTS: Coronary artery stenosis > 50% diameter narrowing was present in 59 patients; the sensitivity (mean +/- SD) of exercise echocardiography was 80 +/- 3%. In 48 patients with an interpretable ECG, the sensitivity of exercise echocardiography was 81 +/- 4%, and that of the exercise ECG was 77 +/- 3% (p = 0.50). In 102 patients without coronary artery disease, the overall specificity of exercise echocardiography was 81 +/- 4%. In 70 patients with an interpretable ECG, the specificity of exercise echocardiography (80 +/- 3%) exceeded that of the exercise ECG (56 +/- 4%, p < 0.0004). The accuracy of exercise echocardiography was also greater than exercise electrocardiography (81 +/- 5% vs. 64 +/- 6%, p < 0.005). Exercise echocardiography stratified significantly more patients of intermediate (20% to 80%) pretest disease probability into the high (> 80%) or low (< 20%) posttest probability group. In women without a previous exercise ECG, the specificity of exercise echocardiography continued to exceed that of exercise electrocardiography (80 +/- 3% vs. 64 +/- 3%, p = 0.05). Exercise echocardiography had the best balance between accuracy and cost for the diagnosis of coronary artery disease in women. CONCLUSIONS: Exercise echocardiography is more specific than exercise electrocardiography for diagnosis of coronary artery disease in women and is a cost-effective approach to the diagnosis of coronary artery disease because of the avoidance of inappropriate angiography.

Adult↗
PubMed1995

Optimal pharmacological stress testing for the diagnosis of coronary artery disease: a probabilistic approach.

Previous reports have suggested that dobutamine stress echocardiography compares favourably with other stress agent-imaging modality combinations for the detection of coronary artery disease. However, in daily clinical practice the value of a test is defined on a probability basis. To study the relative diagnostic contribution of clinical and dobutamine stress test variables, Bayesian analysis was performed in 223 patients with suspected coronary artery disease, who underwent coronary angiography and a high-dose dobutamine stress test in conjunction with electrocardiography, echocardiography and Technetium-99m sestamibi SPECT myocardial perfusion scintigraphy. According to the pre-test (clinical) probabilities, patients were divided into low-, intermediate- and high-risk groups; 155 patients were in the intermediate-risk group. After dobutamine stress echocardiography the number of patients in this intermediate-risk group was reduced to 102 (P < 0.0001). This reduction of patients in the intermediate-risk group by echocardiography was better than perfusion scintigraphy (102 vs 126 patients, P < 0.05) or classic markers of ischaemia such as angina and/or ST-segment changes (102 vs 150, P < 0.0001). Moreover, there was a good correlation between the echocardiographic post-test probabilities and the true distribution of coronary artery disease.

Aged↗
PubMed1995

Recent advances in stress echocardiography.

Stress echocardiography has found acceptance as a routine technique for the diagnosis and evaluation of coronary artery disease. This review concentrates on recent advances in this technique. New approaches including contrast echocardiography, transesophageal stress echocardiography, and color-enhanced wall motion analysis may augment its feasibility and can be used to assist in the interpretation of these studies. The combination of dobutamine with atropine is safe, effective, and superior to the alternatives in patients who cannot exercise. However, in active patients, exercise appears to provide the optimal stress. Finally, recent studies have documented promising results regarding the efficacy of stress echocardiographic techniques for prognostic evaluation and the diagnosis of viable myocardium.

Atropine↗
PubMed1994

Comparison of exercise echocardiography with an exercise score to diagnose coronary artery disease in women.

This study compares the accuracy of the routine exercise electrocardiogram, exercise score, and exercise echocardiography for the diagnosis of coronary artery disease (CAD) in women. Seventy women with a pretest probability of 53 +/- 30% for CAD were stressed using a maximal symptom-limited bicycle exercise protocol. Significant ST-segment change was defined by a depression of > 0.1 mV 0.06 second after the J point. The exercise score was calculated from ST response, heart rate, and workload using an equation derived from a multivariate model. A positive stress echocardiogram was defined by development of a new or worsening wall motion abnormality. The results were compared with the presence or absence of significant (> 50% diameter) stenoses at angiography. Exercise echocardiography identified 29 of the 33 patients (88%) with CAD, compared with 22 (67%) using ST analysis alone, and 20 (61%) using the exercise score (both p < 0.05 vs exercise echocardiography). The specificity of exercise echocardiography (84%) and the multivariate score (73%) were comparable, and exceeded that of the ST analysis (51%) in 37 patients without CAD (p < 0.01). The accuracy of exercise echocardiography (86%) exceeded that of the exercise score (67%, p = 0.01) and ST analysis (59%, p < 0.01). Among all 70 patients, an intermediate (20% to 80%) probability of coronary disease was identified in 21 patients on the basis of exercise echocardiography, in 38 based on the multivariate score, and in 38 based on the ST analysis alone. Exercise echocardiography is more sensitive than the exercise score, and more sensitive and specific than ST-segment analysis for the diagnosis of CAD in women.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

How accurate is dobutamine stress electrocardiography for detection of coronary artery disease? Comparison with two-dimensional echocardiography and technetium-99m methoxyl isobutyl isonitrile (mibi) perfusion scintigraphy.

OBJECTIVES: This study was designed to establish the appropriate diagnostic criteria for positive dobutamine electrocardiographic (ECG) stress test results and to compare their accuracy with those of dobutamine two-dimensional echocardiography and perfusion scintigraphy. BACKGROUND: Conventional criteria for positive findings on ECG exercise testing may not be appropriate for use with dobutamine ECG stress testing. METHODS: One hundred twenty-nine consecutive patients with an interpretable ECG and without previous myocardial infarction were prospectively studied at the time of coronary arteriography. All completed a standard dobutamine protocol (5 to 40 micrograms/kg body weight per min in 3-min dose increments) without side effects. Significant coronary artery disease, defined as > 50% lumen diameter stenosis of a major epicardial coronary artery on coronary angiography, was present in 83 patients. Empiric receiver operating curves were generated for various ECG criteria derived from computer-averaged signals. RESULTS: The best ECG criterion, with a sensitivity of 42% and a specificity of 83%, was an ST segment shift, relative to baseline, of 0.5 mm 80 ms after the J point. The sensitivity of this criterion was greater than that of the conventional criterion of 1-mm ST segment depression 60 (23%) or 80 (18%) ms after the J point, was comparable to that of chest pain occurring during the test (44%, p = NS) but remained inferior to the sensitivities of technetium-99m methoxyl isobutyl isonitrile (mibi) perfusion (76%) or stress echocardiography (76%, p < 0.001, for both). The specificity of this criterion was not significantly different from that of technetium-99m mibi perfusion tomography (65%) or stress echocardiography (89%) but was superior to that of chest pain (59%, p < 0.025). CONCLUSIONS: We conclude that this new criterion for dobutamine electrocardiography is specific but that an imaging technique is still required to accurately predict coronary artery disease.

Adult↗
PubMed1994

Comparative ability of dobutamine and exercise stress in inducing myocardial ischaemia in active patients.

OBJECTIVE: To compare the ability of dobutamine and exercise stress to induce myocardial ischaemia and perfusion heterogeneity under routine clinical circumstances. DESIGN: 86 active patients without previous myocardial infarction were studied by dobutamine and exercise stress protocols and coronary angiography. During both tests patients underwent electrocardiography, digitised echocardiography, and perfusion scintigraphy using Tc-99m methoxybutylisonitrile (MIBI) single photon emission computed tomography. MAIN OUTCOME MEASURE: Coronary disease defined as an ST segment depression of > or = 0.1 mV, a resting or stress induced perfusion defect, or a resting or stress induced wall motion abnormality on exercise and dobutamine stress testing. RESULTS: Dobutamine stress was submaximal in 51 patients because of ingestion of beta adrenoceptor blocking agents on the day of the test (n = 25) or failure to attain the peak dose owing to side effects (n = 28). Exercise was limited in 23 patients by non-cardiac symptoms. The peak heart rate with dobutamine was less than that attained with exercise (105 (25) v 132 (24) beats/min, P < 0.0001); the response to maximal dobutamine stress significantly exceeded that to submaximal stress. Peak blood pressure was greatest with exercise (206 (27) v 173 (25) mm Hg, P < 0.001), values at maximal and submaximal dobutamine stress being comparable. Electrocardiographic evidence of ischaemia was induced less frequently by dobutamine than exercise (32% v 77% of the 56 patients with significant coronary disease, P < 0.01), as was abnormal wall motion (54% v 88%, P < 0.001). Ischaemia was induced more readily with maximal stress of either type; thus the sensitivities of dobutamine and exercise echocardiography were comparable only in patients undergoing a maximal dobutamine testing (73% v 77%, NS). Perfusion heterogeneity was induced in 58% of patients with coronary disease at submaximal dobutamine stress, 73% at maximal dobutamine stress, and 73% at exercise stress (NS). Among 30 patients without coronary stenoses, normal function was obtained in 83% of echocardiography studies with dobutamine and in 80% with exercise (NS). Normal perfusion was identified in 70% of these patients at exercise MIBI, and 68% at dobutamine stress (NS). CONCLUSIONS: In a group of patients studied under normal clinical circumstances antianginal treatment and inability to complete the stress protocol are frequent and compromise the capacity of dobutamine stress to induce ischaemia. In contrast, the induction of perfusion heterogeneity is less susceptible to submaximal stress.

Coronary Angiography↗
PubMed1994

Prognosis of patients with left ventricular dysfunction, with and without viable myocardium after myocardial infarction. Relative efficacy of medical therapy and revascularization.

BACKGROUND: The uptake of F-18 deoxyglucose into dysfunction segments after myocardial infarction identifies metabolically active (FDG+) or inactive (FDG-) myocardium. Although patients with FDG+ segments have been found to be at risk for adverse events, the prognostic significance of viable myocardium in relation to other influences on postinfarction prognosis, including revascularization, remain ill defined. The purpose of this study was to investigate the relative prognostic significance of FDG+ tissue and to establish whether myocardial revascularization in patients with viable tissue attenuates the risk of adverse outcome. METHODS AND RESULTS: One hundred thirty-seven patients with left ventricular dysfunction and resting perfusion defects after myocardial infarction underwent positron emission tomography with both dipyridamole stress Rb-82 perfusion imaging and FDG imaging. After the exclusion of 4 patients proceeding to transplantation, 2 with uninterpretable scans and 2 lost to follow-up, 129 patients were followed clinically for 17 +/- 9 months. Four groups were defined: patients with FDG+ dysfunctional myocardium who were revascularized (n = 49) or treated medically (n = 21) and those with FDG- segments who were revascularized (n = 19) or treated medically (n = 40). The groups of patients with FDG+ or FDG- findings, with and without revascularization, did not differ with respect to known determinants of postinfarction prognosis: age, left ventricular ejection fraction, or the prevalence of multivessel disease. Nonfatal ischemic events occurred in 48% of medically treated FDG+ patients compared with 8% of revascularized patients with FDG+ tissue (P < .001) and 5% of patients with FDG- myocardium (P < .001). Thirteen patients died from cardiac causes; 11 (85%) had a left ventricular ejection fraction of < 30%, and these patients were evenly distributed between FDG+ and FDG- groups. Using Cox's proportional hazards model, only the presence of FDG+ myocardium (odds ratio, 12.9; P < .001) and the absence of revascularization (odds ratio, 5.8; P = .002) independently predicted ischemic events, while only age (P = .02) and ejection fraction (P < .001) but not the presence of viable myocardium were predictive of death. CONCLUSIONS: Residual viable myocardium after myocardial infarction may act as an unstable substrate for further events unless it is revascularized. Despite this association, age and left ventricular dysfunction remained the strongest predictors of cardiac death after myocardial infarction in these patients with a spectrum of left ventricular dysfunction.

Aged↗
PubMed1992

Benefits of intraoperative echocardiography in the surgical management of hypertrophic cardiomyopathy.

OBJECTIVES: The purpose of this study was to determine the role of intraoperative echocardiography in planning the site and extent of myectomy and in ensuring adequate control of the left ventricular outflow tract gradient. BACKGROUND: Although intraoperative echocardiography has been found to be beneficial in patients undergoing valve repair, its impact on surgical decisions in patients undergoing septal myectomy for hypertrophic cardiomyopathy has not been described. METHODS: In 50 patients undergoing septal myectomy over a 5-year period, epicardial echocardiography was performed before cardiopulmonary bypass to establish the extent of outflow tract obstruction, locate its site and plan the myectomy. In 30 patients, transesophageal echocardiography was also used to corroborate data on outflow tract anatomy and examine the mitral valve. RESULTS: In 40 patients (80%) the initial myectomy resulted in a reduction of the maximal outflow tract gradient from 88 +/- 45 to 24 +/- 11 mm Hg, measured by epicardial continuous wave Doppler echocardiography. Ten patients (20%) were shown by postbypass intraoperative echocardiography to have an unsatisfactory result, based on a persistent gradient > 50 mm Hg (n = 7) or persistent mitral regurgitation of greater than moderate severity (n = 3). The postbypass two-dimensional echocardiogram was then used to direct the surgeon toward the most likely site of continued obstruction, and cardiopulmonary bypass was reinstituted to permit further myectomy (n = 9) or mitral valve repair (n = 1). After the second or subsequent period of cardiopulmonary bypass, the outflow tract gradient (26 +/- 14 mm Hg) was substantially reduced and was not significantly different from the postbypass gradient (24 +/- 11 mm Hg) in the group with initial surgical success. At postoperative follow-up (20 +/- 37 weeks), the maximal measured outflow tract gradient (22 +/- 21 mm Hg) showed no difference between patients with immediate surgical success and those requiring a second period of cardiopulmonary bypass for further resection. CONCLUSIONS: Intraoperative echocardiography proved a useful tool to guide the site and extent of septal myectomy, leading to more adequate surgical resection and to persistence of satisfactory control of the outflow tract obstruction into the early follow-up period.

Adult↗
PubMed1992

Prediction by postexercise fluoro-18 deoxyglucose positron emission tomography of improvement in exercise capacity after revascularization.

The extent of ischemic and hibernating myocardium, which may be detected by increased postexercise uptake of fluoro-18 deoxyglucose (FDG) using positron emission tomography, may determine the degree of functional benefit after revascularization. This study examined the influence of the amount of this FDG-avid myocardium on changes in left ventricular function and exercise parameters after revascularization. Echocardiography and exercise testing were performed before and after intervention in 23 patients who had undergone positron emission tomography for the evaluation of myocardial perfusion (using rubidium-82), and postexercise FDG imaging in the fasting state. Follow-up echocardiography (22 +/- 14 weeks after revascularization) was compared with preoperative FDG activity in 7 myocardial regions per patient. Systolic function improved after intervention in 19 of 26 malperfused, dysfunctional FDG-avid regions (73%), and did not improve in 35 of 47 dysfunctional regions without increased FDG uptake (74%). The influence of the amount of FDG-avid tissue on changes in functional state was examined by comparing 9 patients with multiple (greater than or equal to 2) FDG-avid regions with the remainder. Those with multiple FDG-avid regions demonstrated improvement in peak rate-pressure product (20 +/- 4 to 26 +/- 4 x 10(3), p less than 0.02), and percentage of maximal heart rate achieved at peak (84 +/- 10% to 93 +/- 6%, p = 0.04), neither of which changed significantly in the remaining patients. Exercise capacity increased from 5.6 +/- 2.7 to 7.5 +/- 1.7 METS in the group with multiple FDG-avid regions; this increase of 55 +/- 18% exceeded the increase of 13 +/- 10% in the remainder (p = 0.04).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

Identification of recurrent ischemia after coronary artery bypass surgery: a comparison of positron emission tomography and single photon emission computed tomography.

Current techniques for the detection of recurrent coronary stenoses following bypass grafting have shown disappointing diagnostic accuracy. This study used the same dipyridamole-handgrip stress to compare the accuracy of rubidium-82 positron emission tomography and thallium-201 single photon emission computed tomography, in 50 consecutive post-bypass patients undergoing coronary arteriography at a mean interval of 6.5 years after surgery. Significant stenoses in native coronary vessels (greater than 50% diameter) or grafts (greater than 70% diameter) were defined by quantitative angiography. Forty-six patients had recurrent or residual stenoses, 43 (93%) had a perfusion defect identified by positron emission tomography, and 35 (76%) were identified by single photon emission computed tomography (P = 0.04). Fourteen of the 17 patients (82%) without previous Q-wave myocardial infarction were identified by positron emission tomography; 10 of the 17 (59%) were detected by single photon emission computed tomography (P = NS). Stress-induced perfusion defects were demonstrated by positron emission tomography in 19 patients; of this group, thallium imaging identified reversible defects in 11, showed no perfusion defect in 1, and portrayed a persistent defect in 7 patients. Significant graft disease was present in 33 patients; perfusion defects were identified by positron emission tomography in 30 (91%), and by single photon emission computed tomography in 24 (73%, P = NS). Four patients were fully revascularized, without significant recurrent coronary disease; normal perfusion was present in 3 (75%) by positron emission tomography, and 4 (100%) by single photon emission computed tomography.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Accuracy and limitations of exercise echocardiography in a routine clinical setting.

Despite the high reported accuracy of exercise echocardiography in the detection of coronary artery disease, factors that compromise its sensitivity and specificity are less clear. This study examined the results of 179 post-treadmill stress echocardiograms in 150 consecutive patients who also underwent cardiac catheterization and in 29 normal persons at low risk for coronary artery disease. Of 114 patients who had significant coronary stenoses at angiography, 96 had an abnormal exercise echocardiogram (overall sensitivity 84%). False negative results correlated with the performance of submaximal exercise, single-vessel disease and moderate (50% to 70% diameter) stenoses. After the exclusion of seven patients performing submaximal exercise, the sensitivity was 90%. In 54 patients without previous infarction performing maximal exercise, the sensitivity was 87%, higher in patients with multivessel coronary disease (96%) than in those with single-vessel disease (79%). After the exclusion of patients with nondiagnostic results, due either to the performance of submaximal stress or the presence of electrocardiographic (ECG) changes at rest, exercise echocardiography had a higher sensitivity than did exercise electrocardiography (87% vs. 63%, p = 0.01). In 36 patients without significant coronary disease, exercise echocardiography had an overall specificity of 86%. After the exclusion of patients with a nondiagnostic test, exercise echocardiography had a specificity of 82% compared with 74% specificity for exercise electrocardiography (p = NS). Similarly, of the 29 normal subjects, 93% had a normal exercise echocardiogram and 97% had a normal exercise ECG (p = NS). Similarly, of the 29 normal subjects, 93% had a normal exercise echocardiogram and 97% had a normal exercise ECG (p = NS). Age, gender, body weight and image quality did not significantly influence the accuracy of exercise echocardiography.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Effect of Buckberg cardioplegia and peripheral cardiopulmonary bypass on infarct size in the closed chest dog.

OBJECTIVES: To simulate a human catheterization laboratory setting of controlled reperfusion during myocardial infarction, regional infusion of commercially available Buckberg cardioplegic solution and peripheral vented bypass were administered in the closed chest dog. BACKGROUND: Studies in open-chest dogs have demonstrated a significant reduction in infarct size and improvement in regional wall motion with a similar controlled reperfusion method using infusion of substrate-enriched (Buckberg) cardioplegic solution during cardiopulmonary bypass coupled with left ventricular venting. METHODS: After 100 or 180 min of balloon occlusion of the proximal left anterior descending artery, controlled reperfusion was performed with cardioplegic infusion and vented bypass. Dogs matched for occlusion time underwent balloon deflation without bypass or cardioplegia (uncontrolled reperfusion groups). Microspheres were used to quantify coronary ischemia during balloon inflation. All four groups (n = 8 to 9 per group) were followed up at 1 week to determine regional wall motion and infarct size. RESULTS: Qualitative echocardiographic analysis demonstrated no significant difference among groups in recovery of regional wall motion at 1 week; however, wall motion improved significantly in all groups between the ischemia and 1-week recovery periods. The histologic infarct size compared with the area at risk for dogs with uncontrolled versus controlled reperfusion, respectively, was 17.9 +/- 10.5% versus 31.9 +/- 8.3% (p < 0.05) for dogs with 100 min of occlusion and 40.1 +/- 11.7% versus 46.2 +/- 8.4% (p = NS) for dogs with 180 min of occlusion. A greater rate-pressure product in the dogs with controlled reperfusion after 100 min of occlusion (p < 0.05) may explain the larger infarct size observed for that group. CONCLUSIONS: These results demonstrate that regional infusion of substrate-enriched cardioplegic solution in combination with peripheral vented bypass does not further reduce infarct size after prolonged ischemia in the closed chest dog (compared with uncontrolled reperfusion).

Animals↗
PubMed1992

Mitral stenosis in the Maroteaux-Lamy syndrome: a treatable cause of dyspnoea.

The case is reported of a young woman with the Maroteaux-Lamy syndrome (mucopolysaccharidosis type VI) who presented with rapidly progressive dyspnoea due to mitral stenosis. Mitral valve replacement was performed and the appearance of the valve was typical of mucopolysaccharide infiltration. Dyspnoea in patients with the Maroteaux-Lamy syndrome may be due primarily to cardiac valve involvement, and in this setting, valve surgery is safe and effective.

Adult↗
PubMed1992

Metabolic responses of hibernating and infarcted myocardium to revascularization. A follow-up study of regional perfusion, function, and metabolism.

BACKGROUND: The presence of persistent myocardial uptake of 18F-deoxyglucose (FDG) within hypoperfused, dysfunctional segments has been shown to predict the recovery of regional contractile function after revascularization. The spectrum of metabolic responses of such hibernating tissue to revascularization is less clear. METHODS AND RESULTS: Sixteen patients with previous infarction were studied before and after revascularization by myocardial perfusion imaging using 82Rb positron emission tomography, digitized two-dimensional echocardiography, and imaging of postexercise FDG uptake. Hibernation was identified in 35 of 85 segments showing perfusion and wall motion disturbances before intervention. At follow-up (4.9 +/- 2.6 months after revascularization), hibernating segments were characterized by reduction of wall motion score (p less than 0.001), improvement of perfusion (p less than 0.001), and reduction of FDG activity (p less than 0.001). Of the 35 hibernating segments, however, 10 still had abnormal elevation of FDG uptake (greater than 2 SD above normal) without differing from other hibernating segments with respect to postoperative perfusion or wall motion score. Segments with persistently abnormal metabolism were characterized before intervention by more severe malperfusion (p less than 0.01) and greater FDG activity (p less than 0.01). CONCLUSIONS: Although wall motion and perfusion improve with revascularization of hibernating tissue, myocardial metabolism remains abnormal in a significant proportion of segments. These segments are characterized by more extensive perfusion and metabolic changes before revascularization.

Deoxyglucose↗
PubMed1991

Comparison of transcranial Doppler ultrasound and transesophageal contrast echocardiography in the detection of interatrial right-to-left shunts.

Transesophageal contrast echocardiography is an effective but semiinvasive technique for the detection of interatrial right-to-left shunts. Transcranial Doppler ultrasound is an alternative noninvasive method, but may be limited by false-positive diagnoses due to intrapulmonary shunting. This study examined the accuracy of transcranial Doppler for the detection of shunt lesions. Transcranial Doppler of the right middle cerebral artery was performed simultaneously with transesophageal and transthoracic contrast echocardiography in 32 patients using agitated saline contrast during normal respiration and Valsalva. Transesophageal contrast echocardiography diagnosed an interatrial right-to-left shunt in 13 patients and intrapulmonary shunting in 6 patients. Transcranial Doppler identified all 13 interatrial right-to-left shunts and an intrapulmonary shunt in 3 of 6 patients. Absence of a shunt was confirmed by transcranial Doppler in 12 of 12 patients. Transcranial Doppler had a sensitivity of 100% (13 of 13), specificity of 100% (18 of 18) and accuracy of 100% (31 of 31) for prediction of an interatrial right-to-left shunt by transesophageal contrast echocardiography. In comparison, transthoracic contrast echocardiography had a sensitivity of 54% (7 of 13), specificity of 94% (17 of 18) and accuracy of 77% (24 of 31). Thus, transcranial Doppler is highly accurate for detection of an interatrial right-to-left shunt and not compromised by physiologic intrapulmonary shunts, whereas transthoracic contrast echocardiography lacks sensitivity. Transcranial Doppler may be useful as an alternative to transesophageal study, where the primary indication for transesophageal echocardiography is exclusion of an interatrial right-to-left shunt.

Adult↗