N-alpha-tosyl-L-lysine chloromethylketone prevents expression of iNOS in vascular smooth muscle by blocking activation of NF-kappa B

OBJECTIVE: To demonstrate that an agreement approach to applying equations on the basis of clinical and exercise test variables is an accurate, self-calibrating, and cost-efficient method for predicting severe coronary artery disease in clinical populations. DESIGN: Retrospective analysis of consecutive patients with complete data from exercise testing and coronary angiography referred for evaluation of possible coronary artery disease. After developing an equation in a training set, this equation and two other equations developed by other investigators were validated in a test set. The study was performed at two university-affiliated Veteran's Affairs medical centers. PATIENTS: 1080 consecutive men studied between 1985 and 1995 who had coronary angiography within 3 months of the treadmill test. The population was randomly divided into a training set of 701 patients and a test set of 379 patients. Patients with previous coronary artery bypass surgery, valvular heart disease, marked degrees of resting ST depression, and left bundle branch block were excluded. MEASUREMENTS: Recording of clinical and exercise test data along with visual interpretation of the electrocardiogram recordings on standardized forms and abstraction of visually interpreted angiographic data from clinical catheterization reports. RESULTS: Simple clinical and exercise test variables improved the standard application of exercise-induced ST criteria for predicting severe coronary artery disease. By setting probability thresholds for severe disease of <20% and >40% for the three prediction equations, the agreement approach divided the test set into three groups: low risk (patients with all three equations predicting <21% probability of severe coronary disease), no agreement, and high risk (all three equations with >39% probability) for severe coronary artery disease. Because the patients in the no agreement group would be sent for further testing and would eventually be correctly classified, the sensitivity of the agreement approach was 89% and the specificity was 96%. The agreement approach appeared to be unaffected by disease prevalence, missing data, variable definitions, or even angiographic criteria. CONCLUSIONS: Requiring diagnosis of severe coronary disease to be dependent on agreement between these three equations has made them likely to function in all clinical populations. The agreement approach should be an efficient method for the evaluation of populations with varying prevalence of coronary artery disease, limiting the use of more expensive noninvasive and invasive testing to patients with a higher probability of left main or triple-vessel coronary artery disease. This approach provides a strategy that can be applied by inputting the results of basic clinical assessment into a programmable calculator or a computer to assist the practitioner in deciding when further evaluation is appropriate, thus assuring patients access to subspecialty care.     

Accurate detection of coronary artery disease by integrated analysis of the ST-segment depression/heart rate patterns during the exercise and recovery phases of the exercise electrocardiography test

In this comparative cross-sectional study, we evaluated whether a novel computerized diagnostic variable, ST-segment depression/heart rate ST/HR analysis during both the exercise and postexercise recovery phases of the exercise electrocardiography (ECG) test, can detect coronary artery disease more accurately than methods using either exercise or recovery phase alone. The study population comprised 347 clinical patients referred for a routine bicycle exercise ECG test at Tampere University Hospital, Finland. Of these, 127 had angiographically proven coronary artery disease, whereas 13 had no coronary artery disease according to angiography, 18 had no perfusion defect according to technetium-99m sestamibi single-photon emission computed tomography, and 189 were clinically normal with respect to cardiac diseases. For each patient, the maximum values of the ST/HR hysteresis, ST/HR index, end-exercise ST depression, and recovery ST depression were determined from the Mason-Likar modification of the standard 12-lead exercise electrocardiogram [aVL, aVR, and V1 excluded]. The diagnostic performance of these continuous diagnostic variables was compared by means of receiver-operating characteristic analysis. The area under the receiver-operating characteristic curve of the ST/HR hysteresis was 89%, which was significantly larger than that of the end-exercise ST depression (76%, p < or = 0.0001), recovery ST depression (84%, p = 0.0063), or ST/HR index (83%, p = 0.0023), indicating superior diagnostic performance of the ST/HR hysteresis independent of the partition value selection. In conclusion, computerized analysis of the HR-adjusted ST depression pattern during the exercise phase, integrated with the HR-adjusted ST depression pattern during the recovery phase after exercise, can significantly improve the diagnostic performance and clinical utility of the exercise ECG test for the detection of coronary artery disease.     

Ontogeny of thyroid hormone receptors in the brushtail possum (Trichosurus vulpecula)

Exercise electrocardiogram (ECG) has a high rate of false negative results in comparison with simultaneously performed thallium-201 perfusion scintigraphy, particularly in patients with single-vessel coronary artery disease, low exercise workload, inadequate heart rate rise, and resting ECG abnormalities. We present the case of a patient in whom thallium-201 SPECT scintigram revealed equally extensive and severe myocardial ischemia in two myocardial planes opposite each other. The accompanying exercise ECG did not disclose ischemic changes despite the adequacy of heart rate rise in this patient with severe right and left anterior descending coronary artery disease. We propose, as an explanation for this phenomenon, that in this patient the ischemic ST-segment vectors of equal magnitude and direction but of opposite sense, generated during stress, cancelled each other ("ischemic ST-segment counterpoise"), thus rendering the exercise ECG normal.     

Left ventricular hypercontractility and ST segment depression in patients with syndrome X

OBJECTIVES: This study was designed to assess the relation between rest left ventricular function and exercise capacity in patients with syndrome X. BACKGROUND: Clinical observation has suggested that some patients with syndrome X have a high rest left ventricular ejection fraction. In this study we determined the relation between left ventricular ejection fraction and exercise capacity and the electrocardiographic (ECG) changes that develop on exercise. METHODS: The pattern of left ventricular function, exercise capacity and 24-h ambulatory ECG monitoring were studied in 37 patients (9 men, 28 women; mean age 52 +/- 7 years) with syndrome X (angina with normal coronary arteries and a positive exercise test result). All patients had normal findings on echocardiogram and rest ECG. All treatment was discontinued for > or = 48 h. Left ventricular ejection fraction was determined by computerized analysis of the left ventricular angiogram. In patients with syndrome X, exercise duration and heart rate were measured at 1-mm ST segment depression and at peak exercise. RESULTS: Left ventricular hypercontractility (ejection fraction > or = 80%) was observed in 12 patients (32%) (group 1), whereas 25 patients (68%) had normal left ventricular contraction (group 2). The time to 1-mm ST depression on exercise testing was significantly earlier in group 1 than in group 2 (5.13 +/- 1.03 vs. 10.76 +/- 0.63 min, respectively, p < 0.001). The magnitude of the ST segment depression at peak exercise was significantly greater in group 1 than in group 2 (2.03 +/- 0.2 vs. 1.33 +/- 0.05 mm, respectively, p < 0.001). The mean time for ST segment depression to normalize was significantly greater in group 1 than in group 2 (4.76 +/- 0.78 vs. 3.16 +/- 0.39 min, respectively, p < 0.05). Linear regression analysis of all patients with syndrome X showed a significant correlation between exercise duration and ejection fraction (r = 0.55, p < 0.001). The mean circadian variation of heart rate and episodes of ST segment depression on 24-h ambulatory ECG monitoring were similar in the two groups of patients. CONCLUSIONS: These findings indicate that approximately one third of patients with chest pain, normal coronary angiograms and a positive exercise test have left ventricular hypercontractility, and this is associated with the development of ST segment depression at a lower heart rate and work load and a longer time to normalization of ST segment depression after exercise.     

The diagnostic and prognostic importance of ambulatory ST recording compared to a predischarge exercise test after an episode of unstable angina or non-Q wave myocardial infarction

The diagnostic and prognostic value of ambulatory ST recordings after admission to the CCU and before discharge was compared to a symptom-limited predischarge exercise test in 170 men with unstable angina pectoris or non-Q wave myocardial infarction. ST depression in recordings before discharge identified a small group of patients (18%) out of whom 23% had a myocardial infarction within 3 months compared to 7% in those without this finding. The exercise test gave more diagnostic information, with ST depression found in 52% including 70% of those with ST depression at Holter monitoring. After 3 months, 13% of patients with ST depression at exercise test had a myocardial infarction compared to 5% in the other patients. ST depression at exercise also indicated an increased risk of myocardial and future severe angina over a longer time period. Thus ST recordings are recommended before discharge in all patients after an episode of unstable coronary artery disease as it identifies the patients with the most severe prognosis who might benefit from early revascularization. In those without ST depression at Holter a predischarge exercise test will give further information regarding the long-term risk for angina and coronary events.     

Identification of multivessel coronary artery disease by exercise echocardiography

OBJECTIVES: This study examined the ability of exercise echocardiography to identify multivessel coronary artery disease and ascertain its incremental value when combined with clinical and exercise test variables. BACKGROUND: Although exercise echocardiography has been shown to be accurate for the detection of coronary artery disease, little is known about its utility for identifying multivessel involvement, and its incremental value when combined with clinical and exercise test variables has not been studied. METHODS: One hundred fifty consecutive patients were selected on the basis of having had an exercise echocardiographic and a coronary angiographic study within 6 months without any revascularization procedure. Significant coronary artery disease (> or = 50% diameter stenosis in any major coronary artery) was present in 117 patients, and multivessel (two- or three-vessel) disease was present in 90 patients. The exercise echocardiographic studies were reviewed by an experienced observer unaware of the results of the coronary angiogram. RESULTS: The overall sensitivity and specificity of exercise echocardiography for the identification of multivessel disease were 73% and 70%, respectively. A stepwise logistic regression analysis identified the number of abnormal regions on the postexercise images as the strongest independent predictor of multivessel disease; also significant were a history of myocardial infarction and ST segment depression of at least 2 mm on the peak exercise electrocardiogram. CONCLUSIONS: Exercise echocardiography adds independent and incremental information to clinical and exercise test variables for identifying multivessel coronary artery disease.     

The appearance of gallop rhythm after exercise stress testing

BACKGROUND AND HYPOTHESIS: Although it is generally assumed that the appearance of an early diastolic gallop, or third heart sound, appearing immediately after exercise during treadmill stress testing, indicates the presence of serious myocardial disease, no systemically collected data are available to test this hypothesis. METHODS: The author performed auscultation on 3,679 patients undergoing routine treadmill testing together with thallium-201 perfusion scans. Exercise-induced diastolic sounds were related to the available clinical information and electrocardiographic and nuclear test results. These findings were compared with those of 665 randomly selected patients undergoing stress testing in whom such sounds were absent. RESULTS: A total of 165 patients had audible third heart sounds (Group 1). In comparison with those patients lacking such sounds (Group 2), there was a considerably greater prevalence of myocardial scarring (68.5 vs. 26.9%), abnormal lung uptake of thallium (40 vs. 12.8%), diabetes mellitus (20.6 vs. 6.2%), and left bundle-branch block on the resting electrocardiogram (ECG) (15.1 vs. 1.2%). In addition, 65 patients (39.3%) had dilatation of the left ventricle after exercise; 31 (18.8%) of these were also dilated at rest, but only 2 (1.2%) had a drop in blood pressure during stress. In those individuals also subjected to nuclear ventriculography, the average resting ejection fraction was 35%. Estimated exercise capacity was generally reduced in Group 1 (average peak of 6.6 METs), but 29 (17.6%) exceeded 9 METs. Sensitivity and specificity of electrocardiographic ST depression were relatively poor in the detection of perfusion defects within this group (36 and 62%, respectively). Of the 39 patients in Group 1 with a normal resting ECG, 19 (48.7%) had scar (usually posterior or lateral) on nuclear scans. In an additional 10 of this group, nuclear evidence of ischemia (often extensive) was found. CONCLUSIONS: An early or mid-diastolic gallop sound developing after exercise virtually always signifies myocardial disease with reduced myocardial function. Common associated findings are prior infarction (with or without associated ischemia), diabetes, and left bundle-branch block. When found in the presence of a normal resting ECG, this sound commonly signals the presence an occult left ventricular scar and, less commonly, extensive myocardial ischemia. In those patients manifesting such sounds, electrocardiographic ST changes in response to exercise appear limited in the detection of coronary ischemia.     

Exercise-induced ST segment change and coronary risk factors in apparently healthy men

Exercise stress test is useful for the early detection of coronary artery disease and is recommended as a medical clearance test before the initiation of exercise training. However, when applied to apparently healthy people, there are many false positive results. It is therefore necessary to determine indications for stress testing, but few data are available in Japan. In this study, we performed exercise stress test in apparently healthy men to investigate the incidence of exercise-induced ST segment changes and their relationship to coronary risk factors. The subjects were 2,187 men who underwent symptom-limited exercise stress test at a health-promotion center in Tokyo. Those with a history of cardiovascular disease were excluded. They underwent symptom-limited exercise stress test on a treadmill with a modified Bruce protocol or on a cycle ergometer with a ramp protocol (20 watts per minute). Twelve-lead electrocardiogram was recorded every 3 min. Cardiologists evaluated the exercise ECG responses, and advised those with abnormal ST segment changes (Group A) to undergo further examinations at a cardiovascular hospital. The results of further examination such as exercise scintigraphy and/or coronary angiography were obtained. Twice the number of subjects with normal exercise responses were selected as age-matched controls (Group N) to compare the coronary risk factors between the two groups. Twenty-nine subjects had abnormal ST segment changes (1.33% of the total subjects) (Group A). Their mean age was 57 years (38 to 76). Among these, 27 had ST segment depression and 2 had ST elevation.(ABSTRACT TRUNCATED AT 250 WORDS)     

The diagnostic and prognostic value of the 12-lead electrocardiogram in assessing the severity of coronary disease in the acute phase of an acute myocardial infarct

The conventional twelve-lead electrocardiogram (ECG) still is the cheapest, most used and absolutely essential diagnostic method for the acute phase of myocardial infarction (MI) allowing risk stratification and coronary prognostic evaluation in this phase mainly by the localization of the ST segment depression and/or T wave inversion (ST/T changes) not related to the infarct area in Q-Wave MI or at any localization in case of non-Q wave MI. The etiology and pathophysiology of these ST/T changes in the setting of MI has been controversial. With the objective of determining ECG prognostic and diagnostic value, 70 patients (Pts) (59 men and 11 women, mean age 58 + 13) admitted in the acute phase of MI were studied with revision of acute phase ECG ST/T changes. All patients underwent coronary angiography and ventriculography at the moment of hospital discharge. Patients were divided into two classifications: A) MI localization: A1--Q-wave MI (anterior--20 pts, inferior--29 pts, lateral--1 pt); A2--non-Q wave--20 pts. B) Evidence of ST/T changes outside the infarct area in Q wave MI or at any localization in non-Q wave MI (group B1--with ST/T changes, group B2--without ST/T changes). We correlated the angiographically documented coronary artery disease in groups with ST/T changes and their localization. RESULTS: A1) Anterior MI group: in the 6 pts (30%) with "opposite" (inferior) ST/T changes, right coronary artery (RCA) disease was documented in 5 and in the other 14 patients the RCA did not show significant lesions. Inferior MI group: in the 24 Pts (83%) with "opposite" (precordial) ST/T changes. 23 of them had angiographic correlation (left anterior descending (LAD) and/or circumflex (CX) artery disease). Lateral MI group: one Pt with anterior wall ST/T changes and LAD and CX disease. A2) Non-Q wave group: in 13 pts (87%) the diseased vessels were correlated with the site of ST/T changes. B1) Q-Wave AMI: left main and 3-vessel disease in 2 pts, 3-vessel disease in 17 pts, 2-vessel disease in 9 pts, 1-vessel disease in 2 pts and non-significant disease in one pt. Non-Q wave MI: left main and 3-vessel disease in 1 pt, 3-vessel disease in 7 patients, 2-vessel disease in 3 pts and 1-vessel disease in 4 pts. B2) non-Q Wave MI: 3-vessel disease in 5 pts, 2-vessel disease in 7 pts, 1-vessel disease in 6 pts and non-significant disease in 1 pt. Non-Q wave MI: 2-vessel disease in 2 pts and non-significant disease in 1 pt. IN CONCLUSION: When pts were divided according to MI localization, a correlation was found between the ST/T changes outside the infarct area with CAD in 91% of Pts in the Q-Wave infarction group, with more significance in inferior and lateral MI. In the non-Q wave group, we found correlation between the a coronary lesions and the localization of ST/T changes in 87% of the pts. The pt group with ST/T changes presented, when compared with the pt group without these changes, evidence of more severe coronary artery disease (CAD): 3 vessels or left main with 3 vessel disease. However, only in the Q-Wave infarction group was a statistically significant difference found between the group with ST/T changes compared to the group without these changes, concerning to the existence of more severe coronary disease.     

QRS prolongation measured by a new computerized method: a sensitive marker for detecting exercise-induced ischemia

This study compared thallium stress testing and exercise changes in QRS duration using a computerized 'optic scanner' in three groups. Group 1 consisted of 108 subjects with positive exercise ECG tests by ST-T segment criteria and with proven coronary artery disease. Group 2 included 19 subjects with nondiagnostic exercise ECG ST-T changes and with proven coronary artery disease. Group 3 was formed by 38 healthy controls. Group 1: Mean increase in exercise QRS width of 12.4 +/- 14 ms. Group 3: Mean decrease in exercise QRS width of 4.9 +/- 9.3 ms (p < 0.0001). Group 2: Mean QRS prolongation of 7.8 +/- 9.2 ms, which was significantly different from the controls (p < 0.0001) but not from group 1. When compared to thallium stress testing, exercise QRS prolongation had a sensitivity of 93%, specificity of 71%, relative risk of 5, and positive predictive value of 86%. QRS duration measurement can improve the diagnostic accuracy of the exercise ECG stress test.     

Stress echocardiography in the study of the warm-up phenomenon

To date, the "warm-up" phenomenon in patients has been evaluated by ECG and symptom analysis. We investigated the warm-up phenomenon with supine bicycle stress echocardiography in patients with coronary artery disease documented by angiography and positive stress echocardiography. Sixteen coronary artery disease patients (54 +/- 9 years), who were off treatment throughout the study, were enrolled. Each of them underwent two consecutive exercise tests (25 W/2 min) with a 10-min recovery to reestablish baseline conditions. At the end of each stage of exercise and at peak exercise, when wall motion abnormalities (WMA), 1 mm ST depression and angina occurred, and at each minute, for the first 6 min of recovery, a 12-lead ECG was recorded and rate-pressure product was calculated. Time of onset and duration of 1 mm ST depression, WMA and angina, were also determined. Peak WMA, peak wall motion score index, duration of exercise and severity of angina were also evaluated. Exercise time duration and peak rate-pressure product were greater during the second than the first test (p = 0.02, p = 0.03 respectively); the second test also showed a longer delay of the onset of 1 mm ST depression and WMA (p = 0.01, p = 0.01 respectively) and higher rate--pressure product values (p = 0.04, p = 0.03 respectively). On the contrary, wall motion score index during the first and the second test was similar. Time to angina onset was longer during the second test (p = 0.03); the recovery period of ST depression and WMA was shorter during the second test (p = 0.02). In conclusion, these preliminary data show that patients tolerated the second period of ischemia better than the first, consistent with the presence of the warm-up phenomenon. However, the similarity of values of wall motion score index and WMA did not support a reduction in the ischemic area during the second test. This is in contrast with a possible modification of myocardial metabolism which typically underlies the ischemic preconditioning.     

The electrocardiogram during physical stress and Holter monitoring in the detection of asymptomatic myocardial infarct

INTRODUCTION: In patients with myocardial infarction acute myocardial ischaemia could be manifested by characteristic ischaemic symptoms or noncharacteristic symptoms such as cardiac insufficiency or heart rhythm disturbances. Sometimes myocardial ischaemia is not followed by any symptom. This condition is known as asymptomatic myocardial ischaemia. Asymptomatic myocardial ischaemia usually could be detected by treadmill exercise tolerance test or 24-hour Holter ECG monitoring. PATIENTS AND METHODS: We analyzed a group of 58 patients suffering from myocardial infarction with ST segment depression during the treadmill exercise tolerance test. All patients were on Holter 24-hour ECG monitoring. As a criterion of myocardial ischaemia during Holter monitoring ST segment depression of 1 mm and more, lasting 1 minute and more, and 0.08" of J point was accepted. RESULTS: During the treadmill exercise tolerance test segment depression was not followed by any symptom in 18 (31%) patients. There were no differences in the number of patients with hypertension in the group with symptoms and the group without symptoms. Diabetes mellitus was more frequent in the group with asymptomatic myocardial ischaemia. The average values of maximum ST segment depression and heart rates during treadmill tests were not statistically significant in both groups (with and without symptoms). During daily activities myocardial ischaemia was found in 30 (51%) patients by a 24-hour Holter ECG monitoring. We observed 198 episodes of myocardial ischaemia of which 138 (69.1%) were asymtomatic. The amplitude of ST segment depression and duration of these changes were significantly greater in the group with symptomatic episodes than in the group with asymptomatic episodes of myocardial ischaemia. DISCUSSION: Asymptomatic myocardial ischaemia is an often appearance in patients with myocardial ischaemia. Almost in 25% of persons in whom sudden death occurred obstructive changes in coronary arteries during the autopsy were found. Asymptomatic myocardial ischaemia could be found even an a "completely healthy person" without any complaints. Asymptomatic myocardial ischaemia is usually detected in a "completely healthy person" by casual diagnosis, in patients with stable and non stable angina pectoris, in patients with stenosis of the coronary arteries proved by angiography, and in patients after myocardial infarction. Some authors considered that treadmill exercise tolerance testing is less reliable to discover asymptomatic myocardial ischaemia comparing to the continuous 24-hour Holter ECG monitoring. It is know that in patients with diabetes mellitus neuropathy precedes the onset of symptomatic myocardial ischaemia. Asymptomatic myocardial ischaemia has the same predictive value for prognosis of the disease as symptomatic myocardial ischaemia. In some patients "anginal alarm system" is defective, and perception and conduction of pain sensations are disturbed. CONCLUSION: 1. In 31% of patients who suffered from myocardial infarction with ST segment depression during the treadmill testing asymptomatic myocardial ischaemia was found. 2. By Holter monitoring ischaemia ST segment depression during the exertion is observed in 52% of patients. Most of ischaemic episodes were asymptomatic. 3. The amplitude of ST segment depression is significantly greater and duration of depression is significantly longer in symptomatic episodes of myocardial ischaemia comparing to asymptomatic myocardial ischaemia obtained by Holter ECG monitoring.     

Diagnosis of hyperventilation for elimination of false-positive results of physical exercise test

The study was conducted in 55 patients with cardiac pains. Electrocardiography was used successively prior to, during and following physical exercises, followed by Seldinger selective coronary angiography, and electrocardiography prior to, during and following hyperventilation tests. In 2 of 55 patients the result of the exercise test was interpreted as false-positive, since the coronary angiography demonstrated intact vessels, and during hyperventilation ECG recorded a decreased ST segment. To avoid false-positive results in patients with suspected angina pectoris the physical exercises tests can be considered positive only in cases in which hyperventilation caused no ECG changes typical for angina pectoris.     

Selective correlation of amide groups to glycine alpha protons and of arginine guanidine groups to delta protons in proteins by multiple quantum spectroscopy

Study objective: We sought to determine whether electron-beam computed tomography (EBCT) could be used as a triage tool in the emergency department for patients with angina-like chest pain, no known history of coronary disease, normal or indeterminate ECG findings, and normal initial cardiac enzyme concentrations. METHODS: We conducted a prospective observational study of 105 patients admitted between December 1995 and October 1997 to the ED of a large tertiary care hospital with 70,000 annual ED visits. The study group was comprised of women aged 40 to 65 years and men aged 30 to 55 years who presented with angina-like chest pain requiring admission to the hospital or chest pain observation unit. All patients underwent EBCT of the coronary arteries, along with other cardiac testing as deemed necessary by staff physicians. RESULTS: Of the 105 patients, 100 underwent other cardiac testing during hospitalization. Evaluation included treadmill exercise testing in 58, coronary angiography in 25, radionuclide stress testing in 19, and echocardiography in 11. Results of EBCT and cardiac testing were negative for both in 53 patients (53%), positive for both in 14 (14%), positive for tomography and negative for cardiac testing in 32 (32%), and negative for tomography and positive for cardiac testing in only 1 patient. This positive test result, on a treadmill exercise test, was ruled a false positive by an independent staff cardiologist. Two other female patients with normal exercise sestamibi or coronary angiography and EBCT findings also had false-positive treadmill exercise results. The sensitivity of EBCT was 100% (95% confidence interval, 77% to 100%), with a negative predictive value of 100% (95% confidence interval, 94% to 100%). Specificity was 63% (95% confidence interval, 54% to 75%). CONCLUSION: EBCT is a rapid and efficient screening tool for patients admitted to the ED with angina-like chest pain, normal cardiac enzyme concentrations, indeterminate ECG findings, and no history of coronary artery disease. Our study suggests that patients with normal initial cardiac enzyme concentrations, normal or indeterminate ECG findings, and negative results on EBCT may be safely discharged from the ED without further testing or observation. Larger studies are required to confirm this conclusion.     

Cardiac stress testing with thallium-201 imaging reveals silent ischemia in individuals with paraplegia

The purpose of this study was to determine through noninvasive arm ergometry and radionuclide tomographic imaging the presence of latent coronary heart disease (CHD) in subjects with paraplegia. Assessment of CHD in spinal cord injury, using these methods, has not been addressed previously. Twenty asymptomatic subjects with paraplegia performed arm ergometry exercise stress testing with thallium-201 single photon emission computerized tomography (SPECT) or planar myocardial imaging studies. All subjects had normal resting electrocardiograms (ECG). Only five subjects had ECG evidence of ischemia on exercise testing, whereas 13 subjects, including the five subjects with ECG positive stress tests, had scintigraphic evidence of ischemia. Thus, eight subjects would have been undiagnosed for CHD without thallium-201 SPECT imaging. These individuals had multiple risk factors for CHD and, except for age, were without a statistically significant difference between the groups with positive or negative thallium stress imaging studies. Arm ergometry stress thallium imaging shows a high prevalence of ischemia in subjects with paraplegia.     

Intraoperative automated ST segment analysis: a reliable 'black box'?

PURPOSE: To review the application of intraoperative computerized ST analysis and its potential impact on postoperative outcomes. SOURCE: Existing anaesthesia and cardiology literature. PRINCIPAL FINDINGS: Computerized ST analysis was introduced into the operating room using exercise electrocardiographic (ECG) systems. In spite of sophisticated algorithms, errors do occur. Downsloping or horizontal ST depression are the classical criteria for ischaemia. Although algorithms have been developed and evaluated in exercise stress testing, only limited evaluation has been carried out in the operating room. This may be a concern since circumstances in the operating room may frequently lead to false positives. Similarly, studies suggest that all myocardial ischaemia may not exhibit ST changes. The diagnostic accuracy of ST depression in exercise stress testing also cannot be assumed in the operating room. Finally, if ST analysis is applied widely, without considering the population or disease prevalence, misdiagnosis may occur. CONCLUSION: Given the number of anaesthetic tasks at-hand, on-line computerized ST analysis in the operating room can be a useful asset. The technology has its problems and should be applied with an understanding of its limitations and potential for errors. It should be applied in the operating room within the context of the population and disease prevalence.     

Comparison of rest/exercise ECG, thallium-201 scans and radionuclide angiography in patients with suspected coronary artery disease

The results of rest and exercise ECG, 201Tl myocardial perfusion imaging and equilibrium radionuclide angiography were analyzed in 71 consecutive patients referred for diagnosis or evaluation of coronary artery disease (CAD). In 45 patients the diagnosis was established either by catheterization or typical history. In this group the overall sensitivity for rest/exercise ECG was 66%, for 201Tl scans 74%, for both combined 79% and for the ejection fraction response to exercise determined by radionuclide angiography 97%. If only the exercise response was considered, the corresponding sensitivity values were 58% (ECG), 50% (201Tl scans), 71% (ECG + 201Tl) and 97% (radionuclide angiography). The specificity for coronary artery disease was determined to be 71% for ECG, 86% for 201Tl scans and 42% for radionuclide angiography. All patients with false-positive results by radionuclide angiography had cardiomyopathies, thus this test has a high specificity for left ventricular dysfunction rather than for CAD alone. Criteria developed from the analysis of the test results in the 45 patients with definite diagnoses were then applied to the evaluation of 26 additional patients with atypical chest pain. A diagnosis could be made in all but 5 of them and radionuclide angiography was again the single most reliable test. Based on this study a new approach for the noninvasive evaluation of patients with suspected coronary artery disease is proposed.     

Exercise tolerance in asymptomatic elderly men with fluoroscopically detected coronary artery calcification

STUDY OBJECTIVE: The value of detecting coronary artery calcification (CAC), by cardiac imaging, for the diagnosis of coronary artery disease (CAD) in asymptomatic middle-aged men has been demonstrated. However, the incidence of CAC increases with age. The functional significance of CAC remains unknown in asymptomatic elderly men. The purpose of this study is to explore whether CAC in asymptomatic aging men signifies the presence of cardiovascular dysfunction during exercise. DESIGN: This study was designed to address whether elderly asymptomatic men, selected because they have CAC, have reduced exercise tolerance due to functionally significant CAD. Participants and setting: Thirty-eight asymptomatic male volunteers (ages 50 to 75 years, mean [+/-SD] 64+/-7 years) with a normal resting ECG and at least one coronary risk factor, in a population study. Nineteen subjects had CAC detected by digital subtraction fluoroscopy in at least two major coronary arteries, and 19 subjects had no identifiable CAC. METHODS AND RESULTS: Each subject underwent a symptom-limited incremental exercise test with 12-lead ECG monitoring and respiratory gas analysis. Four indexes of exercise oxygen transport were evaluated: peak oxygen uptake (VO2), lactic acidosis threshold, peak VO2/heart rate ratio, and VO2 relative to a work rate increase. Eleven of 38 subjects (28%) were found to have reduced oxygen transport, which was defined as an abnormal reduction in more than two of the above four indexes of oxygen transport. Five of the 11 subjects with reduced oxygen transport had CAC, and 6 subjects did not (not significant). Only one subject with CAC had exercise ST depression. CONCLUSION: Significant CAC in asymptomatic men over age 50 does not signify exercise limitation due to CAD.     

Thallium-201 myocardial scintigraphy in patients with normal coronary arteries and normal left ventriculogram - comparison with hemodynamics, metabolic and morphologic findings (author's transl)

36 consecutive patients with chest pain and/or severe ventricular dysrhythmias, but normal coronary arteries and normal left ventriculogram, underwent thallium-201 myocardial imaging at rest and during exercise. The myocardial scintigram was abnormal in 27 patients (group A) and normal in only 9 patients patients (group B). To answer the question, whether the scintigram was false positive or a correct expression of a myocardial disorder not detectable with angiocardiographic methods, we compared the scintigraphic results with the findings of resting and exercise ECG (n = 36), mean pulmonary artery pressure during exercise (n = 27), myocardial lactate extraction during highrate atrial pacing (n = 14) and light- and electronmicropic examination of right ventricular endomyocardial biopsies (n = 14). The resting ECG was abnormal in 7 of 27 patients of group A and 1 of 9 patients of group B, the exercise ECG in 20 of 27 patients of group A and 1 of 9 patient B. An abnormally elevated exercise pulmonary artery pressure was measured in 10 of 21 patients of group A and 1 of 6 patients of group B. High rate atrial pacing induced an abnormal myocardial lactate extraction in 3 of 13 patients of group A, but not in the single investigated patient of group B. All 12 examined patients of group A and 1 of 2 patients of group B had abnormal biopsy findings. The high incidence of abnormal findings in group A compared to the rare incidence in group B suggests, that the abnormal myocardial scintigrams in patients with chest pain and normal coronary arteries is likely not false positive but reflects a myocardial disorder not being recognized on angiography.     

Quantitative evaluation of treadmill test induced ST-T changes using body surface mapping

Using the ST difference map after the treadmill exercise test, the 26 patients with coronary artery disease were studied. 1) The extent and the speed of complete recovery of ST depression or negative area were well correlated with the severity of coronary artery disease. 2) ST elevation or positive area was correlated with regional asynergies. 3) ST elevation area disclosed regional defect of 201 T1 scintigram at rest, while ST depression area could disclose it infrequently.