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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Twelve patients (8 male and 4 female, age ranged 39-60 years) with suspected coronary arterial disease with left bundle branch block were evaluated for ischemia by simultaneous exercise vectorcardiography and radionuclide-ventriculography. Selective coronary angiography revealed normal coronary arteries in 5 and significant coronary arterial disease in 7 patients. Radionuclide ventriculography revealed no significant difference in resting left ventricular ejection fraction in patients with normal coronary arteries (44.0 +/- 13.9%) and coronary arterial disease (45.7 +/- 11.9%). Exercise radionuclide ventriculography showed positive response suggestive of ischemia in 11 patients (11/12), including all 5 with normal coronary arteries and 6/7 with coronary arterial disease. The magnitude of spatial 'R' maximum cardiac vector in both groups at rest (normal coronary arteries: 1.61 +/- 0.22 mV, coronary arterial disease: 1.63 +/- 0.35 mV) did not show any significant difference. On exercise, the magnitude of spatial 'R' maximum cardiac vector uniformly increased in patients with normal coronary arteries (1.61 +/- 0.22 to 1.75 +/- 0.25 mV, P less than 0.01) and decreased in 6 and remained unchanged in 1 patient with coronary arterial disease (1.63 +/- 0.35 to 1.34 +/- 0.46 mV, P less than 0.01). There was no change in rotational characteristics of QRS and T loops at end exercise in either group. Our preliminary observations indicate that exercise induced alteration of the magnitude of the maximal spatial 'R' cardiac vector appears to be an useful parameter to diagnose underlying coronary arterial disease in patients with left bundle branch block. Having a high false positive response, exercise radionuclide ventriculography appears to be of limited value in these patients.
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PMID:Value of exercise vectorcardiography and exercise radionuclide ventriculography in identification of coronary arterial disease in patients with left bundle branch block. 179 Oct 85

Myocardial thallium-201 (Tl-201) imaging performed in conjunction with exercise stress has enhanced the accuracy of detecting coronary artery disease among patients with chest pain. Sensitivity and specificity of qualitative visual Tl-201 scintigraphy for detection of coronary artery disease average 84% and 87%, respectively. Quantitative analysis of planar Tl-201 scintigrams has yielded sensitivity and specificity in the 90% range. Single photon emission computed tomographic imaging is associated with even higher sensitivity but with specificity in the 82-85% range. Perfusion defects representing ischemia can now be distinguished from scar by demonstration of delayed Tl-201 redistribution or enhanced uptake after reinjection of a second dose of Tl-201. Stenoses of the left circumflex coronary artery are less easily detected than lesions of the right and left anterior descending coronary arteries. False-positive Tl-201 perfusion defects may occur as a result of attenuation artifacts, most often caused by overlying breast tissue or by a high left hemidiaphragm. Patient motion during acquisition of single photon emission computed tomographic images results in artifactual defects on reconstruction. Abnormal Tl-201 uptake has been noted in patients with 1) left bundle branch block and normal coronary arteries, 2) hypertrophic cardiomyopathy, and 3) progressive systemic sclerosis.
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PMID:Diagnostic accuracy of thallium-201 myocardial perfusion imaging. 188 75

Because regional wall motion abnormality (RWMA) is usually noted during ischemia, we hypothesized that the presence of this finding with two-dimensional echocardiography would be superior to conventional methods of diagnosing acute myocardial infarction (AMI) in the emergency room. We also hypothesized that because the absence of RWMA would probably not be associated with AMI, the use of two-dimensional echocardiography would significantly limit unnecessary hospital admissions. To test these hypotheses, we undertook a prospective study that used two-dimensional echocardiography in 180 patients presenting to the emergency room with symptoms suggestive of AMI. The emergency room physicians were not informed of the two-dimensional echocardiography findings, and their decision to admit or not admit to the hospital was based on conventional clinical and electrocardiographic criteria. Forty patients were not admitted to the hospital and 140 were admitted. Of the 30 patients with enzyme-confirmed AMI, nine had typical ST elevation on the ECG that was consistent with acute injury, three had normal ECGs, and eight had ECGs in the presence of which AMI could not have been diagnosed (left bundle branch block, paced rhythm, or repolarization changes); the rest had nonspecific ECG findings. Of the 29 AMI patients with technically adequate two-dimensional echocardiography studies, two did not demonstrate RWMA and 27 had RWMA, compared with nine with diagnostic ECG changes (p less than 0.001). Of the 13 patients with in-hospital complications only four had an initial ECG showing ST elevation, and all 13 had RWMA (p less than 0.001).(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Value of regional wall motion abnormality in the emergency room diagnosis of acute myocardial infarction. A prospective study using two-dimensional echocardiography. 188 10

Electrocardiographic manifestations of ischemia are difficult to interpret in the presence of left bundle branch block (LBBB). Recently developed techniques allow continuous computerized digital analysis of ST segments that can be zeroed to the patient's own baseline electrocardiogram even if that baseline is abnormal conduction. With use of this technology, ST-segment changes during balloon coronary occlusion were compared in 10 patients with LBBB versus an age-, sex-, and coronary anatomy-matched population of 20 control subjects with normal baseline conduction. ST-segment deviation of greater than or equal to 1 mm from baseline was present in 80% of patients with LBBB and in 75% of control patients (difference not significant). There was no significant difference between patients with LBBB versus control patients in maximal ST-segment deviation (2.6 +/- 1.7 vs 2.0 +/- 1.0 mm) or in ST-segment deviation measured after 60 seconds of occlusion (2.4 +/- 1.3 vs 1.8 +/- 1.1 mm). ST-segment deviation reached 1 mm more quickly in patients with LBBB (33 +/- 11 seconds) than in control subjects (60 +/- 36 seconds) (p = 0.003). It is concluded that ST-segment analysis is feasible in patients with LBBB using digital self-referenced ST analysis and may provide important clinical information regarding the presence of myocardial ischemia.
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PMID:Quantification of ST-segment changes during coronary angioplasty in patients with left bundle branch block. 203 44

Two hundred fifty-eight patients were admitted to the hospital for suspected acute myocardial infarction. Electrocardiograms recorded on admission (initial ECG) and the most recent available electrocardiogram recorded before admission (previous ECG) were compared to determine whether changes from the previous to initial ECG predicted acute myocardial infarction or complications of coronary artery disease. Initial ECGs were classed as either positive or negative, with positive indicating either infarction, injury, ischemia, strain, left ventricular hypertrophy, left bundle branch block, or paced rhythm. Negative ECGs were those that did not include any of the positive criteria. Positive and negative ECGs were subgrouped as showing change or no change from previous ECG. We found that patients with a negative initial ECG that had changed from the previous ECG had a 2.1 times greater risk for requiring interventions than those patients whose ECGs were unchanged. We also found that patients with a positive initial ECG that had changed from the previous ECG had a greater risk for interventions (2.0 times), complications (2.6 times), life-threatening complications (4.2 times), and acute myocardial infarction (6.6 times) than the sum of patients in all other ECG categories. We conclude that change is a useful predictor for interventions in patients with negative initial ECGs and a useful predictor for interventions, complications, and acute myocardial infarction in patients with positive initial ECGs.
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PMID:Diagnostic and prognostic importance of comparing the initial to the previous electrocardiogram in patients admitted for suspected acute myocardial infarction. 174 89

Although exercise-induced ST segment depression is thought to be unreliable marker of myocardial ischemia in the presence of resting electrocardiographic changes, this conclusion is based on limited and disparate data from studies often lacking acceptable measures of ischemia. To determine the diagnostic accuracy of the ST segment response in a blinded prospective protocol, we compared ST deviation to thallium201 SPECT scintigraphy in 95 patients during exercise. Diagnostic accuracy was poor in the 95 patients with resting abnormalities: left bundle branch block (LBBB) = 70%, complete right bundle branch block (cRBBB) = 75%, incomplete right bundle branch block (incRBBB) = 79%, intraventricular conduction delay (IVCD) = 44%, left ventricular hypertrophy (LVH) = 59%, digitalis = 53%, compared with a diagnostic accuracy of 90% in 29 patients without resting changes. There were 20 false negative and 17 false positive ST segment responses. The extent and direction of resting ST deviation varied substantially and had no influence on diagnostic accuracy. The extent of change in ST deviation with exercise required for a positive response did not alter diagnostic accuracy: -1.0 mm = 61%, -1.5 mm = 63%, and -2.0 = 61%. While the location of regional ischemia did not influence the accuracy of ST segment analysis, a QRS duration less than 120 msec did improve diagnostic accuracy. Our data confirm that ST segment analysis with exercise testing is not reliable in patients with resting electrocardiographic abnormalities and demonstrates that accuracy is not improved by adjusting for either resting or exercise-induced ST segment changes or for location of the ischemic region.
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PMID:The effect of baseline electrocardiographic abnormalities on the diagnostic accuracy of exercise-induced ST segment changes. 213 78

Thallium-201 myocardial scintigraphy was used to evaluate coronary perfusion in 20 patients with left bundle branch block suspected of having coronary artery disease. Contemporary coronary arteriography was performed in 9 of these patients. Sensitivity and specificity of the method was similar to that obtained in patients without LBBB. A false positive results indicated ischemia of the interventricular septal region in a patient with normal coronary arteries, a known limitation of the method.
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PMID:[The assessment of myocardial perfusion with thallium-201 in patients with a complete left His bundle-branch block]. 215 44

A statistical classification method is suggested for body surface potential maps (BSPM). The initial data reduction utilizes the Fourier expansion and time integration, resulting in physiological-oriented features. Based on Fischer's criterion, optimal discriminant vectors are used to map the features to an optimal subdomain. Experimental criteria determine the dimensionality of the subdomain and the number of features to be mapped into it. Classification is performed in two steps. In the first, a k-nearest neighbor (k-NN) rule is used for every two-category problem, the results of which are fed into a voting rule for final classification. The method is tested with 123 patients divided into four categories: normal (NR), ischemia (IS), myocardial infarction (MI), and left bundle branch block (LB) patients. The success is between 88% (for IS) and 100% (for LB) for QRS segment integration. Departure maps were used to explain the misclassified patterns.
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PMID:Multicategory classification of body surface potential maps. 224 67

The possibility of detecting myocardial infarction in the presence of left bundle branch block by analysis of cardiac and body surface PQRST isoarea maps was studied in nine open-chest and six closed-chest dogs. Recordings were taken during supraventricular drive or right atrial plus right ventricular pacing in control periods and at intervals for up to 10 hr after left anterior descending coronary artery occlusion. Right ventricular pacing was used to simulate left bundle branch block. Myocardial infarction was documented with triphenyl tetrazolium staining. The PQRST areas during supraventricular drive and right atrial plus right ventricular pacing were highly correlated to each other both before and after coronary occlusion. The PQRST isoarea maps after coronary occlusion showed a strong pole overlying the ischemic area on the cardiac surface in open-chest animals and over the left anterior thorax in closed-chest animals. The PQRST pole was positive during the first 1 to 2 hr of occlusion and became negative after several hours. The findings demonstrate that localized abnormalities due to ischemia and infarction are manifest in body and cardiac surface PQRST isoarea maps of both supraventricular complexes and right ventricular paced complexes. The findings suggest that PQRST isoarea maps may aid in identification and localization of ischemic or infarcted myocardium in the setting of abnormal activation such as left bundle branch block.
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PMID:Effects of coronary occlusion on cardiac and body surface PQRST isoarea maps of dogs with abnormal activation simulating left bundle branch block. 245 6

Pathological and clinical studies suggest that platelets play role in the pathogenesis of unstable angina. This study investigated the effect of aspirin on silent episodes of unstable angina. Patient exclusion criteria were acute infarction, left bundle branch block, and ST-depression greater than 0.1 mV in the ECG. 27 patients (pts; 20 m, 7 f; 42-72 yrs) in the CCU with unstable angina were randomized in two groups. Group A received a combination on nitrates, beta-blockers, and calcium entry blockers; in group B aspirin (500 mg/day) was added. 6 h after initiating therapy, Holter-ECG was implemented for 48 h. One pt of group A was excluded owing to infarction within these 48 h. 4 of 13 pts in group A and 5 of 13 in group B showed no ST-Segment abnormalities. 6 pts from each group displayed 2 to 5 ST-depressions greater than 0.1 mV from up to 10 min in 24 h; 3 in group A and 2 in group B had 1-5 lasting 11 to 25 min. In the second 24 h period, the number of ST-depressions decreased distinctly. Statistically, the results obtained did not differ significantly in the two groups. Furthermore, the duration of the silent ischemia did not correlate with the severity of coronary stenosis (angiography 3-8 days after admission). Thus, when combined with the aforementioned triple therapeutic regimen, aspirin does not appear to influence the silent episodes of unstable angina pectoris.
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PMID:[Do thrombocyte aggregation inhibitors modify silent episodes of unstable angina pectoris in combined anti-angina therapy?]. 268 56


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